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ABSTRACT: Background
Although p53 is inactivated by point mutations in many tumors, melanomas infrequently harbor mutations in the p53 gene. Here we investigate the biological role of microRNA-18b (miR-18b) in melanoma by targeting the MDM2-p53 pathway.Methods
Expression of miR-18b was examined in nevi (n = 48) and melanoma (n = 92) samples and in melanoma cell lines and normal melanocytes. Immunoblotting was performed to determine the expression of various proteins regulated by miR-18b. The effects of miR-18b overexpression in melanoma cell lines were investigated using assays of colony formation, cell viability, migration, invasion, and cell cycle and in a xenograft model (n = 10 mice per group). Chromatin immunoprecipitation and methylation assays were performed to determine the mechanism of microRNA silencing.ResultsExpression of miR-18b was substantially reduced in melanoma specimens and cell lines by virtue of hypermethylation and was reinduced (by 1.5- to 5.3-fold) in melanoma cell lines after 5-AZA-deoxycytidine treatment. MDM2 was identified as a target of miR-18b action, and overexpression of miR-18b in melanoma cells was accompanied by 75% reduced MDM2 expression and 2.5-fold upregulation of p53, resulting in 70% suppression of melanoma cell colony formation. The effects of miR-18b overexpression on the p53 pathway and on melanoma cell growth were reversed by MDM2 overexpression. Stable overexpression of miR-18b produced potent tumor suppressor activity, as evidenced by suppressed melanoma cell viability, induction of apoptosis, and reduced tumor growth in vivo. miR-18b overexpression suppressed melanoma cell migration and invasiveness and reversed epithelial-to-mesenchymal transition.Conclusions
Our results demonstrate a novel role for miR-18b as a tumor suppressor in melanoma, identify the MDM2-p53 pathway as a target of miR-18b action, and suggest miR-18b overexpression as a novel strategy to reactivate the p53 pathway in human tumors.
CancerSpectrum Knowledge Environment 01/2013; · 14.07 Impact Factor
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ABSTRACT: BACKGROUND: A minority of patients with T1 melanoma will have a positive sentinel lymph node (SLN) biopsy (SLNB) finding. Identifying who will develop metastatic disease is important in determining prognosis and treatment. OBJECTIVE: We sought to identify clinical and histologic features predictive of a positive SLNB result and determine its prognostic significance in patients with T1 melanoma. METHODS: Clinical and histologic parameters were evaluated in 484 patients with T1 melanoma for their ability to predict a positive SLNB result. The impact of various factors on SLN positivity was evaluated. SLN status was examined as a predictor of overall survival. RESULTS: In all, 34 patients had a positive SLNB finding. Four factors predicted a higher risk of SLN positivity: age 43 years or younger, Breslow depth 0.8 mm or greater, tumors on the lower extremity and trunk, and tumor-infiltrating lymphocyte level. By multivariate analysis, low tumor-infiltrating lymphocytes (P = .0015) and decreasing age (P = .0058) independently predicted SLN positivity. If 0 to 2 of these factors were present, the rate of a positive SLNB result was 3%; this increased to 15% with 3 factors present and to 30% if all 4 factors were present (P < .002). SLN-positive patients had significantly decreased survival (P = .003), and SLN status was the most powerful predictor of survival (P = .009). LIMITATIONS: Our data analysis includes patients from 1994 to 2007 and therefore information on mitotic rate, a recently defined T1b criterion, is not recorded for all patients. CONCLUSIONS: Combining clinical and histologic prognostic factors may help identify subgroups of T1 patients at higher risk of SLN positivity. SLN status has significant prognostic impact in patients with thin melanomas.
Journal of the American Academy of Dermatology 11/2012; · 3.99 Impact Factor
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David De Semir, Mehdi Nosrati,
Vladimir Bezrookove,
Altaf A. Dar,
Scot Federman,
Geraldine Bienvenu,
Suraj Venna,
Javier Rangel,
Joan Climent,
Tanja M. Meyer Tamgüney,
Suresh Thummala,
Schuyler Tong,
Stanley P. L. Leong,
Chris Haqq,
Paul Billings,
James R. Miller III,
Richard W. Sagebiel,
Robert Debs,
Mohammed Kashani-Sabet
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ABSTRACT: Although melanomas with mutant v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) can now be effectively targeted, there
is no molecular target for most melanomas expressing wild-type BRAF. Here, we show that the activation of Pleckstrin homology
domain-interacting protein (PHIP), promotes melanoma metastasis, can be used to classify a subset of primary melanomas, and
is a prognostic biomarker for melanoma. Systemic, plasmid-based shRNA targeting of Phip inhibited the metastatic progression
of melanoma, whereas stable suppression of Phip in melanoma cell lines suppressed metastatic potential and prolonged the survival
of tumor-bearing mice. The human PHIP gene resides on 6q14.1, and although 6q loss has been observed in melanoma, the PHIP locus was preserved in melanoma cell lines and patient samples, and its overexpression was an independent adverse predictor
of survival in melanoma patients. In addition, a high proportion of PHIP-overexpressing melanomas harbored increased PHIP copy number. PHIP-overexpressing melanomas include tumors with wild-type BRAF, neuroblastoma RAS viral (v-ras) oncogene homolog,
and phosphatase and tensin homolog, demonstrating PHIP activation in triple-negative melanoma. These results describe previously
unreported roles for PHIP in predicting and promoting melanoma metastasis, and in the molecular classification of melanoma.
Proceedings of the National Academy of Sciences 04/2012; 109(18):7067-7072. · 9.68 Impact Factor
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David De Semir, Mehdi Nosrati,
Vladimir Bezrookove,
Altaf A Dar,
Scot Federman,
Geraldine Bienvenu,
Suraj Venna,
Javier Rangel,
Joan Climent,
Tanja M Meyer Tamgüney,
Suresh Thummala,
Schuyler Tong,
Stanley P L Leong,
Chris Haqq,
Paul Billings,
James R Miller,
Richard W Sagebiel,
Robert Debs,
Mohammed Kashani-Sabet
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ABSTRACT: Although melanomas with mutant v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) can now be effectively targeted, there is no molecular target for most melanomas expressing wild-type BRAF. Here, we show that the activation of Pleckstrin homology domain-interacting protein (PHIP), promotes melanoma metastasis, can be used to classify a subset of primary melanomas, and is a prognostic biomarker for melanoma. Systemic, plasmid-based shRNA targeting of Phip inhibited the metastatic progression of melanoma, whereas stable suppression of Phip in melanoma cell lines suppressed metastatic potential and prolonged the survival of tumor-bearing mice. The human PHIP gene resides on 6q14.1, and although 6q loss has been observed in melanoma, the PHIP locus was preserved in melanoma cell lines and patient samples, and its overexpression was an independent adverse predictor of survival in melanoma patients. In addition, a high proportion of PHIP-overexpressing melanomas harbored increased PHIP copy number. PHIP-overexpressing melanomas include tumors with wild-type BRAF, neuroblastoma RAS viral (v-ras) oncogene homolog, and phosphatase and tensin homolog, demonstrating PHIP activation in triple-negative melanoma. These results describe previously unreported roles for PHIP in predicting and promoting melanoma metastasis, and in the molecular classification of melanoma.
Proceedings of the National Academy of Sciences 04/2012; 109(18):7067-72. · 9.68 Impact Factor
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ABSTRACT: MicroRNAs (miRNAs) regulate gene expression by repressing translation or directing sequence-specific degradation of complementary mRNA. Here, we report that expression of miR-205 is significantly suppressed in melanoma specimens when compared with nevi and is correlated inversely with melanoma progression. miRNA target databases predicted E2F1 and E2F5 as putative targets. The expression levels of E2F1 and E2F5 were correlated inversely with that of miR-205 in melanoma cell lines. miR-205 significantly suppressed the luciferase activity of reporter plasmids containing the 3'-UTR sequences complementary to either E2F1 or E2F5. Overexpression of miR-205 in melanoma cells reduced E2F1 and E2F5 protein levels. The proliferative capacity of melanoma cells was suppressed by miR-205 and mediated by E2F-regulated AKT phosphorylation. miR-205 overexpression resulted in induction of apoptosis, as evidenced by increased cleaved caspase-3, poly-(ADP-ribose) polymerase, and cytochrome c release. Stable overexpression of miR-205 suppressed melanoma cell proliferation, colony formation, and tumor cell growth in vivo and induced a senescence phenotype accompanied by elevated expression of p16INK4A and other markers for senescence. E2F1 overexpression in miR-205-expressing cells partially reversed the effects on melanoma cell growth and senescence. These results demonstrate a novel role for miR-205 as a tumor suppressor in melanoma.
Journal of Biological Chemistry 03/2011; 286(19):16606-14. · 4.77 Impact Factor
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Horace DeLisser,
Yong Liu,
Pierre-Yves Desprez,
Ann Thor,
Paraskevei Briasouli,
Chakrapong Handumrongkul,
Jonathon Wilfong,
Garret Yount, Mehdi Nosrati,
Sylvia Fong,
Emma Shtivelman,
Melane Fehrenbach,
Gaoyuan Cao,
Dan H Moore,
Shruti Nayak,
Shruti Nyack,
Denny Liggitt,
Mohammed Kashani-Sabet,
Robert Debs
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ABSTRACT: Most patients who die from cancer succumb to treatment-refractory advanced metastatic progression. Although the early stages of tumor metastasis result in the formation of clinically silent micrometastatic foci, its later stages primarily reflect the progressive, organ-destructive growth of already advanced metastases. Early-stage metastasis is regulated by multiple factors within tumor cells as well as by the tumor microenvironment (TME). In contrast, the molecular determinants that control advanced metastatic progression remain essentially uncharacterized, precluding the development of therapies targeted against it. Here we show that the TME, functioning in part through platelet endothelial cell adhesion molecule 1 (PECAM-1), drives advanced metastatic progression and is essential for progression through its preterminal end stage. PECAM-1-KO and chimeric mice revealed that its metastasis-promoting effects are mediated specifically through vascular endothelial cell (VEC) PECAM-1. Anti-PECAM-1 mAb therapy suppresses both end-stage metastatic progression and tumor-induced cachexia in tumor-bearing mice. It reduces proliferation, but not angiogenesis or apoptosis, within advanced tumor metastases. Because its antimetastatic effects are mediated by binding to VEC rather than to tumor cells, anti-PECAM-1 mAb appears to act independently of tumor type. A modified 3D coculture assay showed that anti-PECAM-1 mAb inhibits the proliferation of PECAM-1-negative tumor cells by altering the concentrations of secreted factors. Our studies indicate that a complex interplay between elements of the TME and advanced tumor metastases directs end-stage metastatic progression. They also suggest that some therapeutic interventions may target late-stage metastases specifically. mAb-based targeting of PECAM-1 represents a TME-targeted therapeutic approach that suppresses the end stages of metastatic progression, until now a refractory clinical entity.
Proceedings of the National Academy of Sciences 10/2010; 107(43):18616-21. · 9.68 Impact Factor
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ABSTRACT: IGF-binding protein-3 (IGFBP3) is a member of the IGFBP family, which regulates mitogenic and antiapoptotic effects of IGFs. In this report we evaluated the role of IGFBP3 in melanoma. Quantitative real-time PCR (qRT-PCR), western blot, and ELISA analyses indicated a significant downregulation of IGFBP3 expression in melanoma cell lines as compared with a normal melanocyte cell line. Melanoma cell lines treated with the demethylating agent 5-AZA-2'-deoxycytidine reexpressed IGFBP3 at the mRNA and protein levels. Chromatin immunoprecipitation assays revealed enrichment of acetylated histones H3 and H4, and H3 di- and tri-methylated lysine 4 on the unmethylated IGFBP3 promoter. The IGFBP3 promoter region was highly methylated in human melanoma samples as compared with normal nevi. Overexpression of IGFBP3 in melanoma cells in vitro suppressed tumor cell survival, induced apoptosis, reduced colony formation and invasion, and induced expression of the proapoptotic genes p21, PUMA, and BAX. IGFBP3 overexpression also resulted in cleavage of caspase 3 and reduced expression of phosphorylated AKT. Stable overexpression of IGFBP3 suppressed tumor cell growth in vivo. Our study results indicate that silencing of IGFBP3 in melanoma is due to the methylation of its promoter, and that overexpression of IGFBP3 induces apoptosis and suppresses cell survival and growth.
Journal of Investigative Dermatology 04/2010; 130(8):2071-9. · 6.31 Impact Factor
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Mohammed Kashani-Sabet,
Suraj Venna, Mehdi Nosrati,
Javier Rangel,
Antje Sucker,
Friederike Egberts,
Frederick L Baehner,
Jeff Simko,
Stanley P L Leong,
Chris Haqq,
Axel Hauschild,
Dirk Schadendorf,
James R Miller,
Richard W Sagebiel
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ABSTRACT: To determine the prognostic significance of a multimarker assay incorporating expression levels of three molecular markers in primary cutaneous melanoma.
We assessed expression levels of NCOA3, SPP1, and RGS1 using immunohistochemical analysis in a tissue microarray cohort of 395 patients. For each marker, we identified optimal cut-points for expression intensity to predict disease-specific survival (DSS) and, as a secondary endpoint, sentinel lymph node (SLN) status. The cumulative overexpression of all three markers was embodied in a multimarker index, and its prognostic effect on DSS and SLN status was assessed using Cox regression, Kaplan-Meier analysis, and logistic regression. The prognostic effect of this multimarker assay on DSS was assessed in an independent cohort of 141 patients, in which marker expression levels were scored using immunohistochemical analysis of stained tissue sections.
Increasing multimarker index scores were significantly predictive of reduced DSS and increased SLN metastasis in the 395-patient cohort. Multivariate logistic regression analysis revealed multimarker expression scores as an independent predictor of SLN status (P = 0.001). Multivariate Cox regression analysis showed the independent effect of the multimarker index on DSS (P < 0.001). The multimarker index was the most significant factor predicting DSS when compared with other clinical and histologic factors, including SLN status (P = 0.002). Multimarker expression scores were also the most significantly predictive of DSS in the independent cohort (P = 0.01).
These results describe a multimarker assay with independent prognostic effect on the prediction of survival associated with melanoma in two distinct cohorts.
Clinical Cancer Research 11/2009; 15(22):6987-92. · 7.74 Impact Factor
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ABSTRACT: The histopathological diagnosis of melanoma can be challenging. No currently used molecular markers accurately distinguish between nevus and melanoma. Recent transcriptome analyses have shown the differential expression of several genes in melanoma progression. Here, we describe a multi-marker diagnostic assay using 5 markers (ARPC2, FN1, RGS1, SPP1, and WNT2) overexpressed in melanomas. Immunohistochemical marker expression was analyzed in 693 melanocytic neoplasms comprising a training set (tissue microarray of 534 melanomas and nevi), and 4 independent validation sets: tissue sections of melanoma arising in a nevus; dysplastic nevi; Spitz nevi; and misdiagnosed melanocytic neoplasms. Both intensity and pattern of expression were scored for each marker. Based on the differential expression of these 5 markers between nevi and melanomas in the training set, a diagnostic algorithm was obtained. Using this algorithm, the lesions in the validation sets were diagnosed as nevus or melanoma, and the results were compared with the known histological diagnoses. Both the intensity and pattern of expression of each marker were significantly different in melanomas compared to nevi. The diagnostic algorithm exploiting these differences achieved a specificity of 95% and a sensitivity of 91% in the training set. In the validation sets, the multi-marker assay correctly diagnosed a high percentage of melanomas arising in a nevus, Spitz nevi, dysplastic nevi, and misdiagnosed lesions. The multi-marker assay described here can aid in the diagnosis of melanoma.
Proceedings of the National Academy of Sciences 04/2009; 106(15):6268-72. · 9.68 Impact Factor
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Sima Z Torabian,
David de Semir, Mehdi Nosrati,
Sepideh Bagheri,
Altaf A Dar,
Sylvia Fong,
Yong Liu,
Scot Federman,
Jeff Simko,
Chris Haqq,
Robert J Debs,
Mohammed Kashani-Sabet
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ABSTRACT: IkappaBgamma is one member of a family of proteins that can inhibit the nuclear localization of nuclear factor-kappaB. However, the other specific functions of IkappaBgamma are still poorly understood, and its effects on tumor metastasis have not yet been characterized. We examined the consequences of targeting IkappaBgamma in melanoma cells using a hammerhead ribozyme. We developed stable transformant B16-F10 melanoma cell lines that express a ribozyme that targets mouse IkappaBgamma (IkappaBgamma-144-Rz). Tail-vein injection of B16-F10 cells that stably express IkappaBgamma-144-Rz into mice resulted in a significant reduction of the metastatic potential of these cells. IkappaBgamma-144-Rz-expressing B16 cells were shown to have increased transcriptional activity of nuclear factor-kappaB. We then showed that IkappaBgamma-144-Rz-expressing cells demonstrated both reduced invasion and increased apoptosis, suggesting the existence of pathways through which IkappaBgamma promotes melanoma metastasis. Using gene expression profiling, we identified a differentially expressed gene set that is regulated by the stable suppression of IkappaBgamma that may participate in mediating its anti-metastatic effects; we also confirmed the altered expression levels of several of these genes by quantitative real time polymerase chain reaction. Plasmid-mediated expression of IkappaBgamma-144-Rz produced a significant inhibition of the metastatic progression of B16-F10 cells to the lung and resulted in significant anti-invasive and pro-apoptotic effects on murine Lewis lung carcinoma cells. Our results suggest a novel role for IkappaBgamma in promoting the metastatic progression of melanoma.
American Journal Of Pathology 02/2009; 174(3):1009-16. · 4.89 Impact Factor
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ABSTRACT: RGS1 (regulator of G protein signaling 1) encodes a member of the regulator of G protein family. Recently, RGS1 was found to be overexpressed in gene expression-profiling studies of melanoma. However, no analyses have been reported of its expression at the protein level in melanoma. In this study, the potential impact of RGS1 as a molecular prognostic marker for melanoma was assessed using immunohistochemical analysis of a melanoma tissue microarray containing primary cutaneous melanomas from 301 patients. High RGS1 expression was significantly correlated with increased tumor thickness (P=0.0083), mitotic rate (P=0.04), and presence of vascular involvement (P<0.02). Kaplan-Meier analysis demonstrated a significant association between increasing RGS1 expression and reduced relapse-free survival (P=0.0032) as well as disease-specific survival (DSS) (P=0.018) survival. Logistic regression analysis showed RGS1 overexpression to be significantly correlated to sentinel lymph node metastasis (P=0.04). Multivariate Cox regression analysis showed that increasing RGS1 immunostaining had an independent impact on the relapse-free survival (P=0.0069) and DSS (P=0.0077) of this melanoma cohort. In the analysis of DSS, RGS1 expression level was the most powerful factor predicting DSS. RGS1 immunostaining retained independent prognostic impact even when sentinel lymph node status was included in the prognostic model (P=0.0039). These results validate the role of RGS1 as a novel prognostic marker for melanoma given its impact on the survival associated with melanoma.
The American journal of surgical pathology 06/2008; 32(8):1207-12. · 4.06 Impact Factor
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ABSTRACT: More than 85% of human cancers and over 70% of immortalized human cell lines have highly elevated telomerase activity. In contrast, telomerase activity is down-regulated in most human adult somatic cells, except stem cells and germ cells. These results are consistent with telomerase conferring a selective advantage for continued proliferation of malignant cells and present a unique target for cancer gene therapy. In line with this view, our recent results suggest that knockdown of telomerase RNA in human or in mouse cancer cells by ribozyme or RNA interference (RNAi) diminishes telomerase activity and inhibits cancer cell growth both in vitro and in vivo. Such telomerase inhibiting agents represent a promising novel cancer therapeutic strategy. In this chapter, we will discuss the knockdown of telomerase RNA by hammerhead ribozyme and RNAi. Both techniques are mediated by sequence-specific recognition of target RNA by a guide RNA molecule, which then results in the nucleolytic degradation of the RNA target.
Methods in molecular biology (Clifton, N.J.) 02/2008; 405:113-31.
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ABSTRACT: Osteopontin has been suggested as a marker of disease progression in patients with melanoma because of its overexpression in recent microarray analyses. However, its prognostic role in melanoma has not been fully defined.
Osteopontin expression status was examined using immunohistochemical analysis of a tissue microarray that contained primary cutaneous melanomas from 345 patients. The correlation between osteopontin expression and several histologic markers for melanoma was assessed by using the Chi-square test and the Le directional test. The impact of osteopontin expression on recurrence-free survival (RFS) and disease-specific survival (DSS) of patients with melanoma was examined using Cox regression and Kaplan-Meier analyses. The impact of increasing osteopontin expression on sentinel lymph node (SLN) metastasis was assessed using logistic regression analysis.
High osteopontin expression was associated with increased tumor thickness (P = .037), Clark level (P = .035), and mitotic index (P = .046). Kaplan-Meier analysis demonstrated an association between osteopontin expression and reduced RFS (P < .03) and DSS (P = .05). Multivariate Cox regression analysis demonstrated that high osteopontin immunostaining had an independent impact on the DSS of this melanoma cohort (P = .049). In addition, osteopontin expression was significantly predictive of SLN metastasis (P = .009) and SLN burden, as assessed by the mean number of SLN metastases (P = .0025). Multivariate logistic regression analysis demonstrated an independent role for osteopontin expression in predicting SLN status (P = .0062).
The current results validated the role of osteopontin as an independent prognostic marker for melanoma and provided new evidence for its predictive role in melanoma lymph node metastasis.
Cancer 01/2008; 112(1):144-50. · 4.77 Impact Factor
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ABSTRACT: To date, the major function attributed to telomerase has been the elongation of telomeres. Recent studies have assigned new biochemical properties to telomerase by implicating a role in tumor metastasis and cellular differentiation by virtue of its modulation of novel cell signaling pathways such as glycolysis. In this Perspective we will discuss these recent results that have provided additional insight into the involvement of telomerase in cellular processes other than telomere maintenance at chromosome ends.
Cell cycle (Georgetown, Tex.) 04/2007; 6(5):546-9. · 5.36 Impact Factor
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ABSTRACT: To assess the prognostic significance of nuclear receptor coactivator-3 (NCOA3) overexpression in primary cutaneous melanoma.
NCOA3 expression was assessed using immunohistochemical analysis of a melanoma tissue microarray (TMA) containing primary melanomas from 343 patients with defined histology and follow-up. The impact of the presence or absence of various prognostic factors on relapse-free survival (RFS) and disease-specific survival (DSS) of melanoma patients was assessed using Cox regression and Kaplan-Meier analysis. The impact of presence or absence of various factors on sentinel lymph node (SLN) metastasis was assessed using logistic regression analysis.
Increasing degree of NCOA3 expression was significantly predictive of SLN metastasis (P = .013) and the mean number of SLN metastases (P = .031). Kaplan-Meier analysis demonstrated a significant association between NCOA3 overexpression and reduced RFS (P = .021) and DSS (P = .030). Logistic regression analysis revealed increasing degree of NCOA3 expression to be an independent predictor of SLN status (P = .017). Multivariate Cox regression analysis showed the independent impact of NCOA3 expression on RFS (P = .0095) and DSS (P = .021). NCOA3 was the most powerful factor predicting DSS, outperforming tumor thickness and ulceration.
These results identify NCOA3 as a novel, independent marker of melanoma outcome, with a significant impact on SLN metastasis, RFS, and DSS.
Journal of Clinical Oncology 11/2006; 24(28):4565-9. · 18.37 Impact Factor
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Sepideh Bagheri, Mehdi Nosrati,
Shang Li,
Sylvia Fong,
Sima Torabian,
Javier Rangel,
Dan H Moore,
Scot Federman,
Rebecca R Laposa,
Frederick L Baehner,
Richard W Sagebiel,
James E Cleaver,
Christopher Haqq,
Robert J Debs,
Elizabeth H Blackburn,
Mohammed Kashani-Sabet
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ABSTRACT: Recent studies have demonstrated a role for telomerase in driving tumor progression, but its mechanism of action remains unclear. Here we show that stable, ribozyme-mediated suppression of mouse telomerase RNA reduced telomerase RNA expression, telomerase activity, and telomere length, which significantly reduced tumor invasion and metastatic potential. Our studies reveal that previously unidentified effects of telomerase may mediate its tumor-promoting effects. First, reducing telomerase activity induced a more dendritic morphology, accompanied by increased melanin content and increased expression of tyrosinase, a key enzyme in melanin biosynthesis. Second, gene expression profiling revealed that telomerase targeting down-regulated expression of several glycolytic pathway genes, with a corresponding decrease in glucose consumption and lactate production. Thus, telomerase activity controls the glycolytic pathway, potentially altering the energy state of tumor cells and thereby modulating tyrosinase activity and melanin production. These studies have important implications for understanding the mechanisms by which telomerase promotes tumor invasion and metastasis.
Proceedings of the National Academy of Sciences 08/2006; 103(30):11306-11. · 9.68 Impact Factor
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ABSTRACT: To determine the impact of microsatellites as a prognostic factor in primary cutaneous melanoma.
Retrospective cohort study.
Tertiary referral center. Patients A total of 504 patients with a history of primary melanoma observed for 2 years or having experienced a first relapse.
Overall survival (OS) and relapse-free survival (RFS).
Forty-five patients had evidence of microsatellites in their primary melanoma. Presence of microsatellites significantly correlated with the presence of several other histologic high-risk factors such as tumor thickness, ulceration, Clark level, vascular factors, and mitotic rate. Univariate analysis demonstrated decreased RFS and OS in patients with microsatellites. Presence of microsatellites was associated with increased locoregional metastasis but not distant metastasis. In multivariate analysis, with the inclusion of 6 other clinical and histologic factors, presence of microsatellites was a significant predictor of RFS but not OS. Patients with clinical macrosatellites had a trend toward worsening OS compared with those with microsatellites.
The presence of microsatellites is intimately tied to other markers of melanoma aggressiveness. Microsatellites appear to predict locoregional relapse and RFS but neither distant metastasis nor OS. These results may have implications for patient care as well as the inclusion of microsatellites in stage III of the current classification.
Archives of Dermatology 07/2005; 141(6):739-42. · 3.89 Impact Factor
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Christopher Haqq, Mehdi Nosrati,
Daniel Sudilovsky,
Julia Crothers,
Daniel Khodabakhsh,
Brian L Pulliam,
Scot Federman,
James R Miller,
Robert E Allen,
Mark I Singer,
Stanley P L Leong,
Britt-Marie Ljung,
Richard W Sagebiel,
Mohammed Kashani-Sabet
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ABSTRACT: Because of the paucity of available tissue, little information has previously been available regarding the gene expression profiles of primary melanomas. To understand the molecular basis of melanoma progression, we compared the gene expression profiles of a series of nevi, primary melanomas, and melanoma metastases. We found that metastatic melanomas exhibit two dichotomous patterns of gene expression, which unexpectedly reflect gene expression differences already apparent in comparing laser-capture microdissected radial and vertical phases of a large primary melanoma. Unsupervised hierarchical clustering accurately separated nevi and primary melanomas. Multiclass significance analysis of microarrays comparing normal skin, nevi, primary melanomas, and the two types of metastatic melanoma identified 2,602 transcripts that significantly correlated with sample class. These results suggest that melanoma pathogenesis can be understood as a series of distinct molecular events. The gene expression signatures identified here provide the basis for developing new diagnostics and targeting therapies for patients with malignant melanoma.
Proceedings of the National Academy of Sciences 05/2005; 102(17):6092-7. · 9.68 Impact Factor
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ABSTRACT: To test ribozymes targeting mouse telomerase RNA (mTER) for suppression of the progression of B16-F10 murine melanoma metastases in vivo.
Hammerhead ribozymes were designed to target mTER. The ribozyme sequences were cloned into a plasmid expression vector containing EBV genomic elements that substantially prolong expression of genes delivered in vivo. The activity of various antitelomerase ribozymes or control constructs was examined after i.v. injection of cationic liposome:DNA complexes containing control or ribozyme constructs. Expression of ribozymes and mTER at various time points were evaluated by quantitative real-time PCR. Telomerase activity was examined using the telomeric repeat amplification protocol.
Systemic administration of cationic liposome:DNA complexes containing a plasmid-expressed ribozyme specifically targeting a cleavage site at mTER nucleotide 180 significantly reduced the metastatic progression of B16-F10 murine melanoma. The antitumor activity of the anti-TER 180 ribozyme in mice was abolished by a single inactivating base mutation in the ribozyme catalytic core. The EBV-based expression plasmid produced sustained levels of ribozyme expression for the full duration of the antitumor studies. In addition to antitumor activity, cationic liposome:DNA complex-based ribozyme treatment also produced reductions in both TER levels and telomerase enzymatic activity in tumor-bearing mice.
Systemic, plasmid-based ribozymes specifically targeting TER can reduce both telomerase activity and metastatic progression in tumor-bearing hosts. The work reported here demonstrates the potential utility of plasmid-based anti-TER ribozymes in the therapy of melanoma metastasis.
Clinical Cancer Research 09/2004; 10(15):4983-90. · 7.74 Impact Factor
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ABSTRACT: To examine a model of melanoma progression based on vascular factors and the role of NF-kappa B in the vascular progression of melanoma.
A data set of 526 patients from the University of California San Francisco Melanoma Center with 2 years of follow-up or first relapse was studied. The impact of the presence or absence of various prognostic factors on overall survival of melanoma patients was assessed using Cox regression and Kaplan-Meier analysis. A matched-pair analysis of NF-kappa B expression was performed in cases with vascular involvement and increased tumor vascularity versus matched controls lacking these factors.
Cox regression analysis of factors evaluated by the American Joint Committee on Cancer Melanoma Staging Committee reproduced the powerful impact of tumor thickness and ulceration in this data set. With the inclusion of vascular factors such as tumor vascularity and vascular involvement, ulceration was no longer significant in predicting overall survival. By multivariate analysis, vascular involvement and tumor vascularity were the strongest predictors of melanoma outcome. Tumor vascularity seems to be a precursor of both vascular involvement and ulceration. A matched-pair tissue array analysis demonstrated the significant correlation between overexpression of NF-kappa B-p65 and the development of vascular factors.
Vascular factors play an important role in the progression of malignant melanoma. Ulceration may be a surrogate marker for the interactions between melanoma and the tumor vasculature. NF-kappa B seems to play an important role in the development of these factors.
Journal of Clinical Oncology 03/2004; 22(4):617-23. · 18.37 Impact Factor
