Hong Yu

University of California, Los Angeles, Los Angeles, California, United States

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Publications (22)124.38 Total impact

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    ABSTRACT: Background Pre-clinical studies have implicated hypoxia inducible factor (HIF)-2α as an important oncogene for clear cell renal cell carcinoma (ccRCC). Generally considered to act as a nuclear transcription factor, a recent study has also implicated HIF-2α as a protein translational initiation complex function within the cytoplasm (Uniacke et al., 2012). We hypothesised that both the absolute expression as well as the sub-cellular localisation of HIF-2α would predict clinicopathological features and cancer specific survival (CSS) in ccRCC. Methods A tissue microarray (TMA) study was conducted on three hundred and eight ccRCC patients. Survival differences were investigated with the log rank test and associations with CSS with uni- and multivariate Cox regression analyses. Recursive partition tree analysis was used to identify relevant cutoff values. Results High HIF-2α nuclear (N) (cutoff >32%) expression was associated with smaller tumour sizes (p = 0.002) and lower Fuhrman grades (p = 0.044), whereas tumours with high cytoplasmic (C) HIF-2α (>0%) more often had positive lymph nodes (p = 0.004), distant metastases (p = 0.021) and higher Fuhrman grades (p < 0.0001). After adjustment for TNM stage, Eastern Cooperative Oncology Group performance status (ECOG PS), and Fuhrman grade, both continuous (p < 0.0001) and dichotomised (p < 0.0001) HIF-2α C variables remained significant predictors of CSS, while neither HIF-2α N variable was retained. Conclusion Our investigation supports that HIF-2α may have a unique tumour promoter role in the cytoplasm. This preliminary finding justifies further experimental and mechanistic studies that examine the biological functions of HIF-2α when located in the cytoplasm.
    European journal of cancer (Oxford, England: 1990) 01/2014; · 4.12 Impact Factor
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    ABSTRACT: Insulin-like growth factor binding protein-3 (IGFBP-3) is a pro-apoptotic, anti-metastasic, and anti-angiogenic protein. Low serum IGFBP-3 has been associated with risk of more aggressive prostate cancer (PCa). We investigated the impact of nuclear and cytoplasmic IGFBP-3 protein expression levels in PCa by examining their in situ expression across a wide spectrum of primary tumors by immunohistochemical analysis of tissue microarrays. Immunohistochemistry was performed on PCa microarrays constructed from 226 hormone naïve patients who underwent radical prostatectomy. Both cytoplasmic and nuclear IGFBP-3 expressions were scored in a semi-quantitative fashion using an integrated measure of intensity and positivity. The distribution of IGFBP-3 protein expression was examined across the spectrum of epithelial tissues, and its association with standard clinicopathological covariates and tumor recurrence was examined. There was a broad range of IGFBP-3 staining across all histologies examined. Tumor had higher IGFBP-3 cytoplasmic and nuclear staining than benign histologies. For IGFBP-3 nuclear staining, PCa was significantly different than benign prostatic hyperplasia, normal prostate, and prostate intraepithelial neoplasia. As both a continuous and dichotomized variable, higher nuclear IGFBP-3 expression had statistically significant associations with PCa recurrence. The cytoplasmic staining had no significance in any patient subgroup. In patients with low-grade cancer, IGFBP-3 nuclear positivity was a better predictor of recurrence than baseline PSA, tumor margin status, TNM tumor stage, or presence of capsular invasion. High nuclear IGFBP-3 is amongst the strongest predictors of cancer recurrence in patients with low-grade prostate cancers and may therefore play an important role in risk stratification.
    Hormones and Cancer 09/2012;
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    ABSTRACT: CD44v6 is a cell surface protein involved in cell migration, cell adhesion, tumor progression and metastatic spread. We evaluated its role as a molecular marker for urothelial bladder cancer. A tissue microarray was constructed containing 410 primary urothelial bladder cancers, each in triplicate. Immunohistochemical staining was done with a commercially available antibody. The percent of tumor cells staining positive for CD44v6 was evaluated and we assessed associations with stage, grade and survival. CD44v6 expression was higher in noninvasive (Ta, Tis) vs invasive (T1-T4) tumors (p <0.001). It decreased with increasing grade (p <0.001). In patients who underwent transurethral bladder resection absent CD44v6 expression was associated with a 2.3-fold increased risk of recurrence (95% CI 1.28 to 4.08). Median time to recurrence for tumors with vs without CD44v6 expression was 23 vs 9 months (p = 0.003). In a multivariate Cox model absent CD44 expression was an independent adverse prognostic factor for tumor recurrence (HR 2.33, p = 0.006). In cystectomy cases median overall survival for CD44v6 nonexpression vs expression was 30 vs 75 months (p = 0.0027) and CD44v6 expression was retained as an independent prognostic factor for overall survival (HR 1.54, p = 0.042). Absent CD44v6 expression is an independent adverse predictor of urothelial bladder cancer recurrence and overall survival. Routine evaluation of CD44v6 expression may allow the identification of high risk patients who require more intensive surveillance or aggressive therapy. Targeting of CD44v6 with monoclonal antibodies may provide new avenues for urothelial bladder cancer imaging and treatment.
    The Journal of urology 06/2010; 183(6):2403-8. · 3.75 Impact Factor
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    ABSTRACT: Cancer cells exhibit alterations in histone modification patterns at individual genes and globally at the level of single nuclei in individual cells. We demonstrated previously that lower global/cellular levels of histone H3 lysine 4 dimethylation (H3K4me2) and H3K18 acetylation (ac) predict a higher risk of prostate cancer recurrence. Here we show that the cellular levels of both H3K4me2 and H3K18ac also predict clinical outcome in both lung and kidney cancer patients, with lower levels predicting significantly poorer survival probabilities in both cancer groups. We also show that lower cellular levels of H3K9me2, a modification associated with both gene activity and repression, is also prognostic of poorer outcome for individuals with either prostate or kidney cancers. The predictive power of these histone modifications was independent of tissue-specific clinicopathological variables, the proliferation marker Ki-67, or a p53 tumor suppressor mutation. Chromatin immunoprecipitation experiments indicated that the lower cellular levels of histone modifications in more aggressive cancer cell lines correlated with lower levels of modifications at DNA repetitive elements but not with gene promoters across the genome. Our results suggest that lower global levels of histone modifications are predictive of a more aggressive cancer phenotype, revealing a surprising commonality in prognostic epigenetic patterns of adenocarcinomas of different tissue origins.
    American Journal Of Pathology 05/2009; 174(5):1619-28. · 4.60 Impact Factor
  • The Journal of Urology 04/2009; 181(4):309-309. · 3.75 Impact Factor
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    ABSTRACT: The objective of this study was to evaluate the role of carbonic anhydrase IX (CAIX) in urothelial carcinoma of the bladder. A tissue microarray was constructed that contained 724 tissue samples from 340 patients. Immunohistochemical staining was performed using the antibody MN-75, the percentage of positive cells was evaluated, and their association with tumor (T) classification, grade, and survival was assessed. All normal urothelial tissue samples were negative for CAIX expression, whereas 71% of bladder cancers expressed CAIX. CAIX expression was higher in noninvasive (Ta) versus invasive (T1-T4) tumors (P < .001), in low-grade versus high-grade bladder cancer (P < .001), and in metastases versus the corresponding primary tumor (P = .032). For patients with nonmuscle invasive carcinoma who underwent transurethral resection (TUR), higher CAIX expression was associated with poorer recurrence-free survival (P = .001). In addition, for patients with T1 tumors who underwent TUR, higher CAIX expression conveyed a 6.5-fold higher risk of progression into muscle-invasive disease (P = .006). In patients who underwent cystectomy, higher CAIX expression was associated with worse overall survival (P = .003). Multivariate Cox models revealed that CAIX expression was the strongest, independent prognostic factor of recurrence-free survival (hazard ratio, 2.29; P = .001) and overall survival (hazard ratio, 1.9; P < .001). CAIX was expressed differentially in noninvasive versus invasive tumors, in low-grade versus high-grade bladder cancer, and in primary tumors versus metastases. The current results indicated that CAIX is a strong predictor of recurrence, progression, and overall survival of patients with bladder cancer; and the integration of CAIX expression into conventional prognostic models significantly improved their predictive accuracy. The data suggest a tripartite role of CAIX as a diagnostic, prognostic, and therapeutic molecular marker in bladder cancer.
    Cancer 02/2009; 115(7):1448-58. · 5.20 Impact Factor
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    ABSTRACT: Previous reports have shown elevated arginase activity in prostate cancer patients. This study was designed to compare expression levels of arginase II (AII) in various human prostate cancer cell lines and tissues. Expression levels of AII and other enzymes involved in arginine metabolism were examined in androgen-dependent (LNCaP, LAPC-4) and androgen-independent (PC3, DU145, CL-1, CL-2) prostate cancer cell lines by real-time RT-PCR and Western blot analysis. Further expression analysis of AII was accomplished by immunohistochemical staining of a tissue microarray comprised of 246 primary prostatectomy specimens. In addition, polyamine levels were measured within the prostate cancer cell lines by HPLC. Total polyamines were significantly lower in the androgen-dependent cell lines compared to the androgen-independent cell lines. AII expression was found to be most prominent in the androgen-dependent cell lines and least prominent in the androgen-independent cell lines. Additionally, we found expression of ornithine aminotransferase (OAT), an enzyme also responsible for ornithine production, to be inversely correlated with AII expression. The tissue microarray data revealed that the highest AII expression was seen in BPH, followed by PIN and normal samples, with the lowest expression levels observed in prostate cancer tissues. Moreover, we observed an expression gradient across Gleason grades revealing stronger AII expression in low-grade tumors. The polyamine data, combined with the expression analysis studies, support a possible correlation between AII, OAT, and polyamine synthesis. Based on these results, arginase II expression may play a role in prostate cancer progression. More specifically, the elevated AII expression seen in androgen-dependent and in more differentiated prostate cancers suggests that AII could be a potentially useful marker of early stage prostate adenocarcinoma.
    International Journal of Oncology 03/2008; 32(2):357-65. · 2.66 Impact Factor
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    ABSTRACT: Through its binding with interferon inducible angiostatic chemokines the chemokine receptor CXCR3 has an important role in regulating tumor mediating immunity, angiogenesis and metastatic spread. To evaluate its role in the biology of clear cell renal cell carcinoma we performed a tissue microarray based study. The tissue microarray comprised 154 patients who underwent nephrectomy for localized (N0M0) clear cell renal cell carcinoma at UCLA from 1989 to 2000. Immunohistochemical staining was evaluated by 2 anatomical pathologists who were blinded to outcome. The end point of this study was disease-free survival. Median followup was 5.9 years. A total of 96% of the tumor specimens stained positive for CXCR3. The mean percent of cells staining positive was 68% (range 0 to 100%). CXCR3 expression was not associated with other common clinicopathological features, such as Eastern Cooperative Oncology Group performance status, T stage, Fuhrman grade, vascular invasion or sarcomatoid features. Patients with low CXCR3 expression (less than 30%) had a significantly worse prognosis than patients with high CXCR3 expression with a 5-year disease-free survival rate of 57% vs 82% (p = 0.009). Multivariate Cox regression analysis retained T stage, Eastern Cooperative Oncology Group performance status, sarcomatoid features and CXCR3 as independent prognostic factors. CXCR3 is a novel molecular marker in patients with clear cell renal cell carcinoma. Its higher expression is an independent predictor of improved disease-free survival following nephrectomy for localized disease. Since CXCR3 is not associated with other clinicopathological prognostic factors, it may represent an ideal complementary molecular marker for identifying patients who are at higher risk for recurrence after nephrectomy.
    The Journal of urology 02/2008; 179(1):61-6. · 3.75 Impact Factor
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    ABSTRACT: Na,K-adenosine triphosphatase, which is composed of a catalytic alpha-subunit and a regulatory beta-subunit, generates an electrochemical gradient across the plasma membrane. Previous studies demonstrated altered Na,K-adenosine triphosphatase subunit expression in renal clear cell carcinoma and an association of subunit levels with the prediction of recurrent bladder cancer. We determined the clinical association of protein expression patterns of the Na,K-adenosine triphosphatase alpha1 and beta1-subunits in renal clear cell carcinoma using tissue microarrays with linked clinicopathological data. The UCLA kidney cancer tissue microarray was used to investigate the protein expression of Na,K-adenosine triphosphatase alpha1 and beta1-subunits by immunohistochemistry in 342 patients with renal clear cell carcinoma who were treated with radical nephrectomy. Of these patients clinical outcomes studies were performed in 317. The resultant expression reactivity was correlated with clinicopathological variables. We found that the alpha1-subunit was a significant and independent predictor of disease specific death from renal clear cell carcinoma on multivariate Cox proportional hazards analysis that included established prognostic factors Eastern Cooperative Oncology Group performance status, pT status, metastasis status and tumor grade. Significance was found when examining all patients with clear cell renal cell carcinoma as well as patient substrata with low or high grade tumors and localized or metastatic disease, suggesting that the Na,K-adenosine triphosphatase alpha1-subunit could be used as a new prognosticator for disease specific death from renal clear cell carcinoma. These results suggest that Na,K-adenosine triphosphatase alpha1-subunit expression patterns may be a useful clinical prognosticator for renal clear cell carcinoma. The Na,K-adenosine triphosphatase beta1-subunit was not found to be a useful prognosticator in this setting.
    The Journal of urology 02/2008; 179(1):338-45. · 3.75 Impact Factor
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    ABSTRACT: Hypoxia-inducible factor-1 alpha (HIF-1 alpha) plays an important role in tumoral adaptation to hypoxic conditions by serving as a transcription factor for several crucial proteins, including vascular endothelial growth factor and carbonic anhydrase IX (CAIX). Here, we evaluated the significance of HIF-1 alpha in renal cell carcinoma (RCC). Immunohistochemical analysis was done on a tissue microarray constructed from paraffin-embedded primary tumor specimens from 357 patients treated by nephrectomy for RCC. Nuclear expression was evaluated by a single pathologist who was blinded to outcome. The expression levels were associated with pathologic variables and survival. HIF-1 alpha expression was greater in RCC than in benign tissue. Clear cell RCC showed the highest expression levels. In clear cell RCC, HIF-1 alpha was significantly correlated with markers of apoptosis (p21, p53), the mammalian target of rapamycin pathway (pAkt, p27), CXCR3, and proteins of the vascular endothelial growth factor family. HIF-1 alpha was correlated with CAIX and CAXII in localized, but not in metastatic RCC. HIF-1 alpha expression predicted outcome in metastatic patients: patients with high HIF-1 alpha expression (>35%) had significantly worse survival than patients with low expression (< or =35%); median survival, 13.5 versus 24.4 months, respectively (P = 0.005). Multivariate analysis retained HIF-1 alpha and CAIX expression as the strongest independent prognostic factors for patients with metastatic clear cell RCC. HIF-1 alpha is an important independent prognostic factor for patients with metastatic clear cell RCC. Because HIF-1 alpha and CAIX are independently and differentially regulated in metastatic clear cell RCC, both tumor markers can be complementary in predicting prognosis.
    Clinical Cancer Research 12/2007; 13(24):7388-93. · 7.84 Impact Factor
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    ABSTRACT: The X-linked inhibitor of apoptosis protein (XIAP) is associated with cell survival by blocking caspase-mediated apoptosis. We examined the expression patterns of XIAP with regard to human prostate cancer, predicting that XIAP status may predict cancer recurrence and/or clinical outcome. Immunohistochemistry was done on tissue microarrays constructed from 226 primary prostate cancer specimen. The protein expression distribution was examined across the spectrum of epithelial tissues and its association with standard clinicopathologic covariates and tumor recurrence was examined in 192 outcome-informative patients. The mean XIAP expression was significantly higher in prostate cancer compared with prostatic intraepithelial neoplasia (PIN), normal, and benign prostatic hyperplasia. We observed that XIAP is an independent predictor of tumor recurrence in multivariate Cox proportional hazards analysis in all patients as well as after substratifying by Gleason score. Interestingly, patients with high XIAP levels had a much lower probability of tumor recurrence than those with lower XIAP expression. Even patients with high-grade tumors who had higher XIAP levels had a lower risk of recurrence compared with any patient whose tumors express lower XIAP. XIAP is expressed at higher levels in prostate cancers compared with matched normal tissues. High XIAP expression is strongly associated with a reduced risk of tumor recurrence and is not directly associated with Gleason score, tumor stage, capsular involvement, or preoperative prostate-specific antigen status, suggesting that it is a novel prognosticator and a potential target for prostate cancer diagnosis and therapy. Significantly, these findings provide important and extensive validation of previous results.
    Clinical Cancer Research 11/2007; 13(20):6056-63. · 7.84 Impact Factor
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    ABSTRACT: The mammalian target of rapamycin (mTOR) pathway is up-regulated in many human cancers, and agents targeting the mTOR pathway are in various stages of clinical development. The goal of the study was to evaluate the potential and limitations of targeting the mTOR pathway in renal cell carcinoma (RCC). Immunohistochemical analysis using antibodies against pAkt, PTEN, p27, and pS6 was performed on a tissue microarray constructed from paraffin-embedded specimens from 375 patients treated by nephrectomy for RCC. The expression was associated with pathological parameters and survival. The mTOR pathway was more significantly altered in clear-cell RCC, high-grade tumors, and tumors with poor prognostic features. PS6 and PTEN showed the strongest associations with pathological parameters. Survival tree analysis regarding expression of cytoplasmic pAkt, nuclear pAkt, PTEN, cytoplasmic p27, and pS6 identified staining percentages of 40%, 10%, 75%, 7%, and 70%, respectively, as ideal cutoff values for stratification, with corresponding P-values of .03, .001, .02, .005, and <.0001, respectively. Interestingly, high nuclear pAkt expression was associated with a favorable prognosis, whereas high cytoplasmic pAkt expression was associated with a poor prognosis. In multivariate Cox regression analysis, ECOG PS, T classification, N classification, M classification, cytoplasmic Akt, nuclear pAkt, PTEN, and pS6 were independent prognostic factors of DSS. Components of the mTOR pathway are significantly associated with pathological features and survival. Not all RCC tumor types seem to be equally amenable to mTOR targeted therapy. PTEN, pAkt, p27, and pS6 may serve as surrogate parameters for patient selection and predicting prognosis. Patients with a highly activated mTOR pathway should benefit most from this therapy. External validation of our results is recommended.
    Cancer 07/2007; 109(11):2257-67. · 5.20 Impact Factor
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    ABSTRACT: Shared Pathology Informatics Network (SPIN) is a tissue resource initiative that utilizes clinical reports of the vast amount of paraffin-embedded tissues routinely stored by medical centers. SPIN has an informatics component (sending tissue-related queries to multiple institutions via the internet) and a service component (providing histopathologically annotated tissue specimens for medical research). This paper examines if tissue blocks, identified by localized computer searches at participating institutions, can be retrieved in adequate quantity and quality to support medical researchers. Four centers evaluated pathology reports (1990-2005) for common and rare tumors to determine the percentage of cases where suitable tissue blocks with tumor were available. Each site generated a list of 100 common tumor cases (25 cases each of breast adenocarcinoma, colonic adenocarcinoma, lung squamous carcinoma, and prostate adenocarcinoma) and 100 rare tumor cases (25 cases each of adrenal cortical carcinoma, gastro-intestinal stromal tumor [GIST], adenoid cystic carcinoma, and mycosis fungoides) using a combination of Tumor Registry, laboratory information system (LIS) and/or SPIN-related tools. Pathologists identified the slides/blocks with tumor and noted first 3 slides with largest tumor and availability of the corresponding block. Common tumors cases (n = 400), the institutional retrieval rates (all blocks) were 83% (A), 95% (B), 80% (C), and 98% (D). Retrieval rate (tumor blocks) from all centers for common tumors was 73% with mean largest tumor size of 1.49 cm; retrieval (tumor blocks) was highest-lung (84%) and lowest-prostate (54%). Rare tumors cases (n = 400), each institution's retrieval rates (all blocks) were 78% (A), 73% (B), 67% (C), and 84% (D). Retrieval rate (tumor blocks) from all centers for rare tumors was 66% with mean largest tumor size of 1.56 cm; retrieval (tumor blocks) was highest for GIST (72%) and lowest for adenoid cystic carcinoma (58%). Assessment shows availability and quality of archival tissue blocks that are retrievable and associated electronic data that can be of value for researchers. This study serves to compliment the data from which uniform use of the SPIN query tools by all four centers will be measured to assure and highlight the usefulness of archival material for obtaining tumor tissues for research.
    BMC Cancer 02/2007; 7:37. · 3.33 Impact Factor
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    ABSTRACT: To investigate the expression and potential clinical usefulness of structure-specific flap endonuclease 1 (FEN-1) in human primary prostate cancer using tissue microarray technology, as FEN-1 was recently identified to be overexpressed in CL1.1, the most aggressive clone generated from the hormone-refractory prostate cancer cell line CL1. Immunohistochemistry was performed on tissue microarrays constructed from paraffin-embedded specimens of primary prostate cancer from 246 patients who had had a radical prostatectomy. Prostatic intraepithelial neoplasia (PIN), benign prostatic hyperplasia (BPH) and normal prostate epithelium were represented on the array. FEN-1 nuclear expression was scored based on the percentage of target cells staining positively, and correlated with Gleason score, preoperative prostate-specific antigen (PSA) level and pathological stage. The time to PSA recurrence was also analysed. The mean expression of FEN-1 was significantly higher in cancer (36.7%) than in normal (13.2%), BPH (4.5%) and PIN (15.4%) specimens (P < 0.001). FEN-1 expression was significantly correlated with Gleason score (ó = 0.23, P = 0.002). A higher preoperative serum PSA level (P = 0.015), Gleason score > or = 7 (P < 0.001), seminal vesicle invasion (P < 0.001) and capsular involvement (P = 0.004) were associated with PSA recurrence, whereas FEN-1 expression was not. In a multivariate analysis, only Gleason score > or = 7 (P < 0.001), seminal vesicle invasion (P = 0.005) and capsular involvement (P = 0.009) were retained as independent predictors for PSA recurrence. FEN-1 is overexpressed in prostate cancer compared with matched normal prostate, and its expression increases with tumour dedifferentiation, as shown by increasing Gleason score. These results suggest that FEN-1 might be a potential marker for selecting patients at high risk, and a potential target for prostate cancer diagnosis and therapy.
    BJU International 08/2006; 98(2):445-51. · 3.05 Impact Factor
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    ABSTRACT: Aberrations in post-translational modifications of histones have been shown to occur in cancer cells but only at individual promoters; they have not been related to clinical outcome. Other than being targeted to promoters, modifications of histones, such as acetylation and methylation of lysine and arginine residues, also occur over large regions of chromatin including coding regions and non-promoter sequences, which are referred to as global histone modifications. Here we show that changes in global levels of individual histone modifications are also associated with cancer and that these changes are predictive of clinical outcome. Through immunohistochemical staining of primary prostatectomy tissue samples, we determined the percentage of cells that stained for the histone acetylation and dimethylation of five residues in histones H3 and H4. Grouping of samples with similar patterns of modifications identified two disease subtypes with distinct risks of tumour recurrence in patients with low-grade prostate cancer. These histone modification patterns were predictors of outcome independently of tumour stage, preoperative prostate-specific antigen levels, and capsule invasion. Thus, widespread changes in specific histone modifications indicate previously undescribed molecular heterogeneity in prostate cancer and might underlie the broad range of clinical behaviour in cancer patients.
    Nature 07/2005; 435(7046):1262-6. · 38.60 Impact Factor
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    ABSTRACT: Approximately 30% of renal cell carcinomas (RCCs) present as metastatic disease. Molecular markers have the potential to characterize accurately the biological behavior of tumors and they may be useful for determining prognosis. A custom tissue array was constructed using clear cell RCC from 150 patients with metastatic RCC who underwent nephrectomy prior to immunotherapy. The tissue array was stained for 8 molecular markers, namely Ki67, p53, gelsolin, carbonic anhydrase (CA)9, CA12, PTEN (phosphatase and tensin homologue deleted on chromosome 10), epithelial cell adhesion molecule and vimentin. Marker status and established clinical predictors of prognosis were considered when developing a prognostic model for disease specific survival. On univariate Cox regression analysis certain markers were statistically significant predictors of survival, namely CA9 (p <0.00001), p53 (p = 0.0072), gelsolin (p = 0.030), Ki67 (p = 0.036) and CA12 (p = 0.043). On multivariate Cox regression analysis that included all markers and clinical variables CA9 (p = 0.00002), PTEN (p <0.0001), vimentin (p = 0.0032), p53 (p = 0.028), T category (p = 0.0025) and performance status (p = 0.0013) were significant independent predictors of disease specific survival and they were used to construct a combined molecular and clinical prognostic model. The bias corrected concordance index (C-index) of this combined prognostic model was C = 0.68, which was significantly higher (p = 0.0033) than that of a multivariate clinical predictor model (C = 0.62) based on the UCLA Integrated Staging System (T category, histological grade and performance status). In patients with clear cell RCC a prognostic model for survival that includes molecular and clinical predictors is significantly more accurate than a standard clinical model using the combination of stage, histological grade and performance status.
    The Journal of Urology 05/2005; 173(5):1496-501. · 3.75 Impact Factor
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    ABSTRACT: An accurate system for predicting survival for patients with solid tumors will allow for better patient selection for both established and novel therapies. We propose a staging system for clear cell variants of renal cell carcinoma (RCC) that includes molecular predictors and standard clinical predictors such as tumor-node-metastasis (TNM) stage, histological grade, and performance status (PS). A custom tissue array was constructed using clear cell RCC from 318 patients, representing all stages of localized and metastatic RCC, and immunohistochemically stained for molecular markers Ki67, p53, gelsolin, CA9, CA12, PTEN, EpCAM, and vimentin. We present a strategy for evaluating individual candidate markers for prognostic information and integrating informative markers into a multivariate prognostic system. The overall median follow-up and the median follow-up for surviving patients were 28 and 55 months, respectively. A prognostic model based primarily on molecular markers included metastasis status, p53, CA9, gelsolin, and vimentin as predictors and had high discriminatory power: its statistically validated concordance index (C-index) was found to be 0.75. A prognostic model based on a combination of clinical and molecular predictors included metastasis status, T stage, Eastern Cooperative Oncology Group PS, p53, CA9, and vimentin as predictors and had a C-index of 0.79, which was significantly higher (P < 0.05) than that of prognostic models based on grade alone (C = 0.65), TNM stage alone (C = 0.73), or the University of California Los Angeles integrated staging system (C = 0.76). Protein expressions obtained using widely available technology can complement standard clinical predictors such as TNM stage, histological grade, and PS.
    Clinical Cancer Research 09/2004; 10(16):5464-71. · 7.84 Impact Factor
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    ABSTRACT: Arginase, often perceived solely as the last of the now six enzymes of the urea cycle, exists in two forms and has a broad tissue distribution. A cytosolic form, AI, is highly expressed in the liver and is thought to be primarily involved in ureagenesis. A mitochondrial form, AII, has been thought to be more widely expressed and to be involved in the biosynthesis of polyamines, the amino acids ornithine, proline, and glutamate and in the inflammatory process, among others. This paper will address recent experiments that cast some doubt on the validity of these distinctions. Studies have now suggested that macrophages may express AI or AII in different experimental conditions, both in vivo and in vitro. In contrast, most studies, at least in cell culture, suggest that AII may be most highly expressed in cancers of a number of different types. Inhibition of arginase activity in vivo and in vitro has implicated this activity in maintaining ornithine levels for polyamine synthesis. In situ and "quantitative" PCR studies in mouse have demonstrated that AI and not AII is the predominant isoform expressed during development and in the majority of organs. Mouse knockout models for both AI and AII have been produced and are available to address their functions. Surprisingly, the AII knockout animal has no apparent phenotype except for some diminished fertility in homozygous males, consistent with the belief that AII, highly expressed in prostate, is important for sperm function in semen. The AI knockout animal has a more dramatic phenotype and dies at 10-12 days of life of hyperammonemia. The reason for the prolonged survival, as compared to other urea cycle knockout animals, may be due to the later occurrence of hypo-ornithinemia, a contention not yet proven. Transgenic manipulation of the AI knockout animal and breeding the AI and AII knockouts into single animals may address the ability of AII to rescue animals from some of the metabolic consequences of AI deficiency, as appears to happen in man. Newborn screening has given particular hope to patients affected by arginase (AI) deficiency. Increased arginine appears to be detectable by newborn screening with tandem mass spectrometry and the past years continue to demonstrate the therapeutic effectiveness of dietary management of the disorder, with patients treated from birth remaining normal and those treated late, ceasing to deteriorate and even improving in cognitive and physical functioning. Finally, prenatal diagnosis appears to be possible as was predicted, but never proven, some years ago.
    Molecular Genetics and Metabolism 05/2004; 81 Suppl 1:S38-44. · 2.83 Impact Factor
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    ABSTRACT: Arginase I (AI), the fifth and final enzyme of the urea cycle, detoxifies ammonia as part of the urea cycle. In previous studies from others, AI was not found in extrahepatic tissues except in primate blood cells, and its roles outside the urea cycle have not been well recognized. In this study we undertook an extensive analysis of arginase expression in postnatal mouse tissues by in situ hybridization (ISH) and RT-PCR. We also compared arginase expression patterns with those of ornithine decarboxylase (ODC) and ornithine aminotransferase (OAT). We found that, outside of liver, AI was expressed in many tissues and cells such as the salivary gland, esophagus, stomach, pancreas, thymus, leukocytes, skin, preputial gland, uterus and sympathetic ganglia. The expression was much wider than that of arginase II, which was highly expressed only in the intestine and kidney. Several co-localization patterns of AI, ODC, and OAT have been found: (a) AI was co-localized with ODC alone in some tissues; (b) AI was co-localized with both OAT and ODC in a few tissues; (c) AI was not co-localized with OAT alone in any of the tissues examined; and (d) AI was not co-localized with either ODC or OAT in some tissues. In contrast, AII was not co-localized with either ODC or OAT alone in any of the tissues studied, and co-localization of AII with ODC and OAT was found only in the small intestine. The co-localization patterns of arginase, ODC, and OAT suggested that AI plays different roles in different tissues. The main roles of AI are regulation of arginine concentration by degrading arginine and production of ornithine for polyamine biosynthesis, but AI may not be the principal enzyme for regulating glutamate biosynthesis in tissues and cells.
    Journal of Histochemistry and Cytochemistry 10/2003; 51(9):1151-60. · 2.26 Impact Factor
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    ABSTRACT: We are using the model of the developing mouse embryo to elucidate the pattern of arginase expression in mammalian cells in normal animals and in arginase I (AI) deficiency during development by digoxigenin-labeled RNA in situ hybridization. Our goal is to understand the regulation of these isozymes, with the expectation that this knowledge will help patients suffering from AI deficiency. We found that AI mRNA was widely and strongly expressed in the normal developing mouse embryo; in contrast, a relatively strong AII mRNA signal was found only in the intestine. In the AI knockout mouse embryo, no AII overexpression was found. These results indicated that arginases are needed in mouse embryonic development and AI is the principal form required. The strong AI expression in the peripheral nervous system suggests that the pathogenesis of the neurological retardation in AI deficiency may be conditioned by AI deficiency in the nervous system during embryonic development.
    Mechanisms of Development 08/2002; 115(1-2):151-5. · 2.38 Impact Factor

Publication Stats

1k Citations
124.38 Total Impact Points

Institutions

  • 2003–2014
    • University of California, Los Angeles
      • • Department of Pathology and Laboratory Medicine
      • • Department of Urology
      Los Angeles, California, United States