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Juan Chen,
Anthony W H Chan,
Ka-Fai To,
Weixian Chen,
Zhenzhen Zhang,
Jihua Ren,
Chunli Song,
Yue-Sun Cheung,
Paul B S Lai, Suk-Hang Cheng,
Margaret H L Ng,
Ailong Huang,
Ben C B Ko
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ABSTRACT: BACKGROUND: The yeast silent information regulator 2 (SIR2) is a histone deacetylase that utilizes NAD(+) as a cofactor for its functions. In mammals, SIR2 is represented by seven homologues (SIRT1-7). Sirtuin 1 (SIRT1), the prototypical member of this family, has been implicated in telomere maintenance and the growth of hepatocellular carcinoma (HCC). Nevertheless, the role of other sirtuins in the pathogenesis of HCC remains elusive. RESULTS: We found that Sirtuin 2 (SIRT2), another member of sirtuin family, also contributes to cell motility and invasiveness of HCC. SIRT2 is up-regulated in HCC cell lines and in a subset of human HCC tissues (23/45). Up-regulations of SIRT2 in primary HCC tumors were significantly correlated with the presence of microscopic vascular invasion (p=0.001), a more advanced tumor stage (p=0.004) and shorter overall survival (p=0.0499). Functional studies by shRNA-mediated suppression of SIRT2 expression in HCC cell lines revealed significant inhibition of motility and invasiveness. Depletion of SIRT2 also led to the regression of epithelial-mesenchymal transition (EMT) phenotypes, whereas the ectopic expression of SIRT2 in the immortalized hepatocyte cell line L02 enhanced the expression of EMT markers, and promoted cell motility and invasiveness. Mechanistic studies revealed that SIRT2 regulates the deacetylation and activation of Akt, which subsequently impinges on the GSK-3β/β-catenin signaling pathway to regulate EMT. Concordantly, we showed that there is a positive correlation between the level of SIRT2 and β-catenin in human HCC. CONCLUSIONS: Our findings have uncovered a novel role of SIRT2 in HCC metastasis, and provide a rationale to explore the use of sirtuin inhibitors in HCC therapy. (HEPATOLOGY 2013.).
Hepatology 01/2013; · 11.66 Impact Factor
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Chi Keung Cheng,
Tsz Ki Kwan,
Chi Ying Cheung,
Kitty Ng,
Pei Liang, Suk Hang Cheng,
Natalie P H Chan,
Rosalina K L Ip,
Raymond S M Wong,
Vincent Lee,
Chi Kong Li,
Sze Fai Yip,
Margaret H L Ng
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ABSTRACT: Nucleophosmin, encoded by NPM1, is a haploinsufficient suppressor in hematological malignancies. NPM1 mutations are mostly found in acute myeloid leukemia patients with normal karyotype and associated with favorable prognosis. A polymorphic nucleotide T deletion with unknown significance is present in the NPM1 3'-untranslated region. Here, we showed that the homozygous nucleotide T deletion was associated with adverse outcomes and could independently predict shortened survival in patients with de novo acute myeloid leukemia. Mechanistically, we demonstrated that the nucleotide T deletion created an illegitimate binding site for miR-337-5p, which was widely expressed in different acute myeloid leukemia subtypes and inhibited NPM1 expression. Accordingly, NPM1 levels were found to be significantly reduced and correlated with miR-337-5p levels in patients carrying a homozygous nucleotide T deletion genotype. Together, our findings uncover a microRNA-mediated control of NPM1 expression that contributes to disease heterogeneity and suggest additional prognostic values of NPM1 in acute myeloid leukemia.
Haematologica 10/2012; · 6.42 Impact Factor
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ABSTRACT: Background PF4, platelet factor 4, is an angiostatic chemokine suppressing tumor growth and metastasis. We previously revealed frequent transcriptional silencing of PF4 in multiple myeloma, but the functional roles are still unknown. Design and Methods We studied the apoptotic effects of PF4 on myeloma cell lines and primary myeloma in vitro, and investigated the involving signaling pathway. The in vivo effects were also studied by SCID mouse model. Results PF4 not only suppressed myeloma-associated angiogenesis, but also inhibited growth and induced apoptosis in myeloma cells. We found that PF4 negatively-regulated STAT3 and concordantly inhibited constitutive and IL-6-induced phosphorylation of STAT3, and down-regulated the expression of STAT3 target genes (Mcl-1, Survivin and VEGF). Overexpression of constitutively activated STAT3 could rescue PF4-induced apoptotic effects. Furthermore, we found that PF4 induced the expression of SOCS3, a STAT3 inhibitor, and gene silencing of SOCS3 abolished its ability to inhibit STAT3 activation, suggesting a critical role of SOCS3 in PF4-induced STAT3 inhibition. Knockdown of LRP1, a putative PF4 receptor, could also abolish PF4-induced apoptosis and STAT3 inhibition. Finally, the tumor growth inhibitory effect of PF4 was confirmed by in vivo mouse models. Immunostaining of rabbit bone xenografts from PF4-treated mice showed induction of apoptosis of myeloma cells and inhibition of angiogenesis, which was associated with suppression of STAT3 activity. Conclusions Together, our preclinical data indicate that PF4 may be a potential new targeting agent for treatment of myeloma.
Haematologica 08/2012; · 6.42 Impact Factor
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Yingduan Cheng,
Pei Liang,
Hua Geng,
Zhaohui Wang,
Lili Li, Suk Hang Cheng,
Jianming Ying,
Xianwei Su,
Ka Man Ng,
Margaret H L Ng,
Tony S K Mok,
Anthony T C Chan,
Qian Tao
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ABSTRACT: Epigenetic disruption of tumor suppressor genes is frequently involved in tumorigenesis. We identified a novel 19q13 KRAB domain-containing zinc finger protein, ZNF545/ZFP82, broadly expressed in normal tissues but downregulated in multiple tumor cell lines. The ZNF545 promoter contains a CpG island, which is frequently methylated in cell lines. The transcriptional silencing of ZNF545 could be reversed by pharmacologic or genetic demethylation, indicating direct epigenetic silencing. ZNF545 was also frequently methylated in multiple primary tumors of nasopharyngeal, esophageal, lung, gastric, colon, and breast, but rarely in normal epithelial tissues and paired normal tissues. ZNF545 is located in the nucleus and mainly sequestered in nucleoli, functioning as a repressor. ZNF545 is able to repress NF-κB and AP-1 signaling pathways, whereas ectopic expression of ZNF545 in silenced tumor cells significantly inhibited their growth and induced apoptosis. Functional studies showed that ZNF545 was involved in ribosome biogenesis through inhibiting the activity of rDNA promoter and decreasing cellular protein translation efficiency. Thus, we identified ZNF545 as a novel tumor suppressor inducing tumor cell apoptosis, repressing ribosome biogenesis and target gene transcription. The tumor-specific methylation of ZNF545 could be an epigenetic biomarker for cancer diagnosis.
Molecular Cancer Research 06/2012; 10(7):925-36. · 4.29 Impact Factor
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ABSTRACT: The mammalian target of rapamycin (mTOR) and the microtubules are prominent druggable targets for hepatocellular carcinoma (HCC). PI3K/Akt/mTOR activation is associated with resistance to microtubule inhibitors. Here, we hypothesized that co-targeting of mTOR (by mTOR inhibitor temsirolimus) and the microtubule (by microtubule-destabilizing agent vinblastine) would be more efficacious than single targeting in HCC models. In vitro studies showed that effective inhibition of mTOR signaling with temsirolimus alone was able to suppress HCC cell growth in a dose-dependent manner. Among five cell lines tested, Huh7 was the most temsirolimus-sensitive (IC(50)=1.27±0.06μM), while Hep3B was the most temsirolimus-resistant (IC(50)=52.95±17.14μM). We found that co-targeting of mTOR (by temsirolimus) and the microtubule (by vinblastine, at low nM) resulted in marked growth inhibition in Huh7 cells and synergistic growth inhibition in Hep3B cells (achieving maximal growth inhibition of 80-90%), demonstrating potent antitumor activity of this novel combination. In vivo studies showed that temsirolimus treatment alone for 1 week was able to inhibit the growth of Huh7 xenografts. Strikingly, the temsirolimus/vinblastine combination induced a significant and sustained antitumor activity (up to 27 days post-treatment), with effective reduction of tumor vessel density in both Huh7 and Hep3B xenograft models. Mechanistic investigation revealed that this marked antitumor effect was accompanied by specific and concerted down-regulation of several key anti-apoptotic/survival proteins (survivin, Bcl-2, and Mcl-1), which was not observed in single agent treatments. Our findings demonstrated that the potent anti-cancer activity of this co-targeting strategy was indeed mediated in parts by inhibition of these key survival/anti-apoptotic proteins.
Biochemical pharmacology 01/2012; 83(9):1146-58. · 4.25 Impact Factor
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ABSTRACT: Secreted-frizzled related proteins (SFRPs) are modulators of the Wnt signaling pathway that is closely involved in normal and malignant hematopoiesis. Epigenetic deregulation of Wnt modulators leading to aberrant signaling has been reported in adult patients with acute myeloid leukemia (AML), but its occurrence in childhood patients with AML and the role of individual modulators are unclear. In this study, we examined SFRP1, SFRP2, SFRP4, and SFRP5 promoter methylation in 83 patients with AML (59 children and 24 adults) and found preferential SFRP1 methylation and mRNA down-regulation in the prognostically favorable subgroup of AML with t(8;21) translocation. Among the 4 genes, SFRP1 methylation independently predicted prolonged event-free and relapse-free survivals in childhood patients with nonacute promyelocytic leukemia with nonadverse cytogenetics. Mechanistically, we further demonstrated that RUNX1-ETO, the t(8;21) fusion product, specifically bound the SFRP1 promoter and repressed its transcription via a consensus RUNX binding site. In t(8;21)-leukemia cells, SFRP1 selectively inhibited canonical Wnt signaling and cellular proliferation that were associated with concomitant down-regulation of Wnt/β-catenin target genes, including CCND1 and MYC. Taken together, we identified SFRP1 as a transcriptional repression target of the t(8;21) fusion protein and demonstrated a novel mechanism of Wnt activation in a specific subtype of AML.
Blood 12/2011; 118(25):6638-48. · 9.90 Impact Factor
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Yun-Kwok Wing,
Lei Chen,
Siu-Ping Lam,
Albert M Li,
Nelson L S Tang,
Margaret H L Ng, Suk-Hang Cheng,
Crover K W Ho,
V Mok,
Ho-Wan Leung,
Alexander Lau,
Michael Ho-Ming Chan,
Hiu-Shuen Chan,
Paul S K Chan
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ABSTRACT: To determine the familial aggregation of narcolepsy from perspectives of clinical symptomatology, polysomnographic data, and human leukocyte antigen (HLA) typing.
This was a Family study at the University-affiliated hospital. The participants were narcolepsy probands and their first degree relatives, and, also, age and sex matched unrelated healthy controls. Interventions were not applicable.
All study subjects underwent structured interviews, overnight polysomnography followed by a multiple sleep latency test (MSLT), and HLA typing. Altogether, 33 probands and 81 first degree relatives (response rate 65%) were recruited. Among the relatives, 12.3% were diagnosed with narcolepsy and 39.5% had narcolepsy spectrum as defined by unexplained abnormal MSLT (shortened MSL and SOREMP) results. The relative risk of narcolepsy in first degree relatives was 361.8. Familial aggregation of narcolepsy symptoms, excessive daytime sleepiness, HLA status, abnormal MSLT, and nocturnal polysomnographic findings were observed.
The familial risk of narcolepsy among first degree relatives is much higher than previously reported. There exists a spectrum of narcolepsy features among relatives, ranging from full clinical tetrads to asymptomatic abnormal MSLT findings.
Sleep Medicine 12/2011; 12(10):947-51. · 3.40 Impact Factor
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ABSTRACT: Nasopharyngeal cancer (NPC) is a highly prevalent and invasive head and neck cancer in Asia. Disease recurrence and distant metastasis account for major NPC deaths. Therefore, more effective therapy is needed. Lapatinib, a dual tyrosine kinase inhibitor (TKI) against both EGFR and HER-2, has been known to exert potent antitumor activity against several cancer models. Given that both EGFR and HER-2 are co-expressed in NPC, we hypothesized that dual targeting of EGFR and HER-2 by this small molecule EGFR/HER-2 TKI would elicit anti-tumor activity in NPC. Using in vitro models of NPC, we demonstrated that lapatinib was able to efficiently inhibit the phosphorylation of both EGFR and HER-2. This was accompanied by significant growth inhibition of NPC cells (with maximal growth inhibition >90%). For the most lapatinib-sensitive cell line (HK1-LMP1, with IC(50) ∼ 600 nM), which harbored the highest levels of both EGFR and HER-2, inhibition of cell growth was associated G(0)/G(1) cell cycle arrest, marked PARP cleavage, caspase-3 cleavage, as well as significant downregulation of several important survival proteins (e.g. survivin, Mcl-1 and cyclin D1). NPC cells are intrinsically invasive. We found that lapatinib was able to inhibit cellular invasion of both HK1-LMP1 and HONE-1 cells. Furthermore, our data demonstrated for the first time that lapatinib harbored potent anoikis-sensitization activity (i.e. sensitizing cancer cells to detachment-induced apoptosis) in human cancer cells overexpressing both EGFR and HER-2 (HK1-LMP1 and HK1). Taken together, our findings suggest that lapatinib is a promising anti-cancer agent for NPC with anti-invasion and anoikis-sensitization activities.
Investigational New Drugs 12/2011; 29(6):1241-52. · 3.36 Impact Factor
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Juan Chen,
Bin Zhang,
Nathalie Wong,
Anthony W I Lo,
Ka-Fai To,
Anthony W H Chan,
Margaret H L Ng,
Cecilia Y S Ho, Suk-Hang Cheng,
Paul B S Lai,
Jun Yu,
Ho-Keung Ng,
Ming-Tat Ling,
Ai-Long Huang,
Xue-Fei Cai,
Ben C B Ko
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ABSTRACT: Hepatocellular carcinoma (HCC) is a highly malignant tumor with a poor prognosis. Treatment of HCC is complicated by the fact that the disease is often diagnosed at an advanced stage when it is no longer amenable to curative surgery, and current systemic chemotherapeutics are mostly inefficacious. Sirtuin 1 (SIRT1) is a class III histone deacetylase that is implicated in gene regulations and stress resistance. In this study, we found that SIRT1 is essential for the tumorigenesis of HCC. We showed that although SIRT1 was expressed at very low levels in normal livers, it was overexpressed in HCC cell lines and in a subset of HCC. Tissue microarray analysis of HCC and adjacent nontumoral liver tissues revealed a positive correlation between the expression levels of SIRT1 and advancement in tumor grades. Downregulation of SIRT1 consistently suppressed the proliferation of HCC cells via the induction of cellular senescence or apoptosis. SIRT1 silencing also caused telomere dysfunction-induced foci and nuclear abnormality that were clearly associated with reduced expressions of telomerase reverse transcriptase (TERT), and PTOP, which is a member of the shelter in complex. Ectopic expression of either TERT or PTOP in SIRT1-depleted cells significantly restored cell proliferation. There was also a positive correlation between the level of induction of SIRT1 and TERT [corrected] in human HCC. Finally, SIRT1-silencing sensitized HCC cells to doxorubicin treatment. Together, our findings reveal a novel function for SIRT1 in telomere maintenance of HCC, and they rationalize the clinical exploration of SIRT1 inhibitors for HCC therapy.
Cancer Research 06/2011; 71(12):4138-49. · 7.86 Impact Factor
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Yingduan Cheng,
Hua Geng, Suk Hang Cheng,
Pei Liang,
Yan Bai,
Jisheng Li,
Gopesh Srivastava,
Margaret H L Ng,
Tatsuo Fukagawa,
Xiushan Wu,
Anthony T C Chan,
Qian Tao
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ABSTRACT: Zinc finger transcription factors are involved broadly in development and tumorigenesis. Here, we report that the little studied zinc finger transcription factor ZNF382 functions as a tumor suppressor in multiple carcinomas. Although broadly expressed in normal tissues, ZNF382 expression was attenuated in multiple carcinoma cell lines due to promoter CpG methylation. ZNF382 was also frequently methylated in multiple primary tumors (nasopharyngeal, esophageal, colon, gastric, and breast). Ectopic expression of ZNF382 in silenced tumor cells significantly inhibited their clonogenicity and proliferation and induced apoptosis. We further found that ZNF382 inhibited NF-kappaB and AP-1 signaling and downregulated the expression of multiple oncogenes including MYC, MITF, HMGA2, and CDK6, as well as the NF-kappaB upstream factors STAT3, STAT5B, ID1, and IKBKE, most likely through heterochromatin silencing. ZNF382 could suppress tumorigenesis through heterochromatin-mediated silencing, as ZNF382 was colocalized and interacted with heterochromatin protein HP1 and further changed the chromatin modifications of ZNF382 target oncogenes. Our data show that ZNF382 is a functional tumor suppressor frequently methylated in multiple carcinomas.
Cancer Research 08/2010; 70(16):6516-26. · 7.86 Impact Factor
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ABSTRACT: Sunitinib is a multi-target receptor tyrosine kinase (RTK) inhibitor against vascular endothelial growth factor receptors, platelet-derived growth factor receptors (PDGFR), c-kit and RET. Several of these RTKs are known to be involved in the progression of nasopharyngeal carcinoma (NPC). Here, we evaluated the preclinical activities of sunitinib in NPC.
We determined the basal level of total and phosphorylated PDGFR, c-kit and RET by immunoblotting in a panel of five NPC cell lines. The effect of sunitinib on NPC cell proliferation was evaluated by MTT assay. We further studied the effect of sunitinib on NPC cell cycle progression and apoptosis. We investigated the in vitro and in vivo activities of sunitinib as single agent and in combination with cisplatin or docetaxel in NPC cell lines and tumor xenografts.
Sunitinib exhibited dose-dependent growth inhibition in all NPC cell lines tested with IC(50) between 2-7.5 μM and maximum inhibition of over 97%. Sunitinib induced apoptosis and cell cycle arrest at G(0)/G(1) phase. In vitro, sunitinib moderately enhanced the growth inhibition of cisplatin or docetaxel. Single agent sunitinib demonstrated significant growth inhibition, reduced microvessel density and caused extensive tumor necrosis in a NPC xenograft model. However, concurrent administration of sunitinib and docetaxel induced severe toxicity in mice without enhanced antitumor effect.
Single agent sunitinib demonstrated potent in vitro and in vivo growth inhibition in NPC. When combined with chemotherapy, sequential instead of concurrent administration schedule should be further explored.
Investigational New Drugs 05/2010; 29(6):1123-31. · 3.36 Impact Factor
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Betty Y K Law,
Mingfu Wang,
Dik-Lung Ma,
Fawaz Al-Mousa,
Francesco Michelangeli, Suk-Hang Cheng,
Margaret H L Ng,
Ka-Fai To,
Anthony Y F Mok,
Rebecca Y Y Ko,
Sze Kui Lam,
Feng Chen,
Chi-Ming Che,
Pauline Chiu,
Ben C B Ko
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ABSTRACT: Emerging evidence suggests that autophagic modulators have therapeutic potential. This study aims to identify novel autophagic inducers from traditional Chinese medicinal herbs as potential antitumor agents. Using an image-based screen and bioactivity-guided purification, we identified alisol B 23-acetate, alisol A 24-acetate, and alisol B from the rhizome of Alisma orientale as novel inducers of autophagy, with alisol B being the most potent natural product. Across several cancer cell lines, we showed that alisol B-treated cells displayed an increase of autophagic flux and formation of autophagosomes, leading to cell cycle arrest at the G(1) phase and cell death. Alisol B induced calcium mobilization from internal stores, leading to autophagy through the activation of the CaMKK-AMPK-mammalian target of rapamycin pathway. Moreover, the disruption of calcium homeostasis induces endoplasmic reticulum stress and unfolded protein responses in alisol B-treated cells, leading to apoptotic cell death. Finally, by computational virtual docking analysis and biochemical assays, we showed that the molecular target of alisol B is the sarcoplasmic/endoplasmic reticulum Ca(2+) ATPase. This study provides detailed insights into the cytotoxic mechanism of a novel antitumor compound.
Molecular Cancer Therapeutics 03/2010; 9(3):718-30. · 5.23 Impact Factor
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Brigette B Y Ma,
Vivian W Y Lui,
Fan Fong Poon,
S C Cesar Wong,
Ka-Fai To,
Elaine Wong,
Honglin Chen,
Kwok-Wai Lo,
Qian Tao,
Margaret Heung Ling Ng, Suk Hang Cheng,
Anthony T C Chan
Investigational New Drugs 02/2010; · 3.36 Impact Factor
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Vivian Wai Yan Lui,
Cecilia Pik Yuk Lau,
Crystal Sao Fong Cheung,
Kakiu Ho,
Margaret Heung Ling Ng, Suk Hang Cheng,
Bo Hong,
Sai-Wah Tsao,
Chi Man Tsang,
Kenny Ieng Kit Lei,
Yasundo Yamasaki,
Akira Mita,
Anthony T C Chan
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ABSTRACT: 1-(3-C-ethynyl-beta-d-ribo-pentofuranosyl)cytosine (ECyd) is a ribose-modified nucleoside analog of cytidine with potent anticancer activity in several cancers. The main antitumor mechanism of this promising RNA-directed nucleoside anti-metabolite is efficient blockade of RNA synthesis in cancer cells. Here, we examined the therapeutic potential of this RNA-directed anti-metabolite in in vitro models of nasopharyngeal cancer (NPC). In a panel of 6 NPC cell lines, ECyd effectively inhibited cellular proliferation at nM concentrations (IC(50): approximately 13-44nM). Moreover, cisplatin-resistant NPC cells were highly sensitive to ECyd (at nM concentration). The ECyd-mediated growth inhibition was associated with G(2)/M cell cycle arrest, PARP cleavage (a hallmark of apoptosis) and Bcl-2 downregulation, indicating induction of apoptosis by ECyd in NPC cells. Unexpectedly, ECyd-induced significant downregulation of TIGAR, a newly described dual regulator of apoptosis and glycolysis. More importantly, this novel action of ECyd on TIGAR was accompanied by marked depletion of NADPH, the major reducing power critically required for cell proliferation and survival. We hypothesized that ECyd-induced TIGAR downregulation was crucially involved in the antitumor activity of ECyd. Indeed, overexpression of TIGAR was able to rescue NPC cells from ECyd-induced growth inhibition, demonstrating a novel mechanistic action of ECyd on TIGAR. We demonstrated for the first time that an RNA-directed nucleoside analog, ECyd, exerts its antitumor activity via downregulation of a novel regulator of apoptosis, TIGAR. Moreover, ECyd may represent a novel therapy for NPC.
Biochemical pharmacology 02/2010; 79(12):1772-80. · 4.25 Impact Factor
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ABSTRACT: Hypoxia is commonly developed in solid tumors, which contributes to metastasis as well as radio- and chemo-resistance. Nasopharyngeal carcinoma (NPC) is a highly invasive and metastatic head and neck cancer prevalent in Southeast Asia with a high incidence rate of 15-30/100,000 persons/year (comparable to that of pancreatic cancer in the US). Previous clinical studies in NPC showed that hypoxia is detected in almost 100% of primary tumors and overexpression of hypoxia markers correlated with poor clinical outcome. Tirapazamine (TPZ) is a synthetic hypoxia-activated prodrug, which preferentially forms cytotoxic and DNA-damaging free radicals under hypoxia, thus selectively eradicate hypoxic cells. Here, we hypothesized that specific hypoxia-targeting by this clinical trial agent may be therapeutic for NPC. Our findings demonstrated that under hypoxia, TPZ was able to induce preferential growth inhibition of NPC cells, which was associated with marked cell cycle arrest at S-phase and PARP cleavage (a hallmark of apoptosis). Examination of S-phase checkpoint regulators revealed that Chk1 and Chk2 were selectively activated by TPZ in NPC cells under hypoxia. Hypoxia-selectivity of TPZ was also demonstrated by preferential downregulation of several important hypoxia-induced markers (HIF-1α, CA IX and VEGF) under hypoxia. Furthermore, we demonstrated that TPZ was equally effective and hypoxia-selective even in the presence of the EBV oncoprotein, LMP1 or the EBV genome. In summary, encouraging results from this proof-of-concept study implicate the therapeutic potential of hypoxia-targeting approaches for the treatment of NPC.
Investigational New Drugs 12/2009; 29(3):401-10. · 3.36 Impact Factor
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ABSTRACT: YC-1 has recently been demonstrated to have potent anti-invasion and anti-metastatic activity in several cancer models, in addition to its anti-proliferation activity. However, the mechanism underlying its anti-invasion/anti-metastatic activity is largely unknown. Nasopharyngeal carcinoma (NPC) is a highly metastatic head and neck cancer in Southeast Asia. Here, we demonstrated that YC-1 inhibited invasiveness and proliferation of NPC cells, with the latter being accompanied by PARP cleavage, S-phase arrest and activation of Chk1/Chk2. We aimed at identifying novel anti-invasion mechanisms of YC-1 in NPC by a functional proteomic platform, the reverse phase protein array (RPPA). Our study revealed for the first time that multiple invasion-related signaling proteins (beta-catenin, caveolin, Src and EGFR), as well as several growth-related proteins (AMPKalpha, phospho-acetyl-CoA carboxylase (p-ACC), HER-2 and mTOR), which were previously un-described signaling proteins altered by YC-1, were found to be down-modulated by YC-1 in NPC cells. We hypothesized that YC-1-mediated downregulation of these invasion proteins contributed to its anti-invasion activity in NPC cells. Overexpression of EGFR, activated Src or caveolin, but not beta-catenin reversed the inhibitory effects of YC-1 on NPC cell invasion, with EGFR and activated Src having additional effects on rescuing NPC cells from YC-1-mediated growth inhibition. In summary, we have identified several novel anti-invasion mechanisms of YC-1 that could impact NPC, and possibly other cancers as well.
Biochemical pharmacology 10/2009; 79(6):842-52. · 4.25 Impact Factor
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Brigette B Y Ma,
Vivian W Y Lui,
Fan Fong Poon,
S C Cesar Wong,
Ka Fai To,
Elaine Wong,
Honglin Chen,
Kwok Wai Lo,
Qian Tao,
Anthony T C Chan,
Margaret Heung Ling Ng, Suk Hang Cheng
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ABSTRACT: This study evaluated the preclinical activity and molecular predictors of response to gefitinib (Iressa(R), Astra Zeneca Inc, UK) in nasopharyngeal carcinoma (NPC). The activity of gefitinib was evaluated in four human NPC cell lines--HK1, HONE-1, CNE2, C666-1. A representative gefitinib-sensitive (HK1, IC(50) = 250 nM) and gefitinib-resistant cell line (HONE-1, IC(50) > 15 microM) were selected and compared for expression of epidermal growth factor receptor (EGFR) and related ligands, and activation of downstream proteins. Gefitinib induced G1 cycle arrest, apoptosis and inhibited cell invasion more significantly in HK1 than HONE-1 cells. HK1 expressed higher levels of p-EGFR, lower p-AKT and phospho-signal transducer and activator of transcription 3 (p-STAT3) than other cell lines. EGFR gene was found to be amplified in HK1. Gefitinib at IC(50) concentrations significantly suppressed EGF-induced activation of p-EGFR, phospho-mitogen-activated protein kinase (p-MAPK) and p-STAT3, but p-AKT showed persistent activation in HK1 and HONE-1 cells. There was no difference in EGFR-ligand expression between the 4 NPC cell lines. In NPC samples derived from non-responders to gefitinib, 50% and 60% showed cytoplasmic and nuclear pi-EGFR expression, respectively, and 33% showed p-AKT expression. EGFR or KRAS mutations were not detected. This study suggests that most NPC cell lines are intrinsically resistant to gefitinib (except HK1 cells), and further studies are needed to confirm whether EGFR gene amplification and persistent AKT activation may influence response to gefitinib in NPC.
Investigational New Drugs 09/2009; 28(3):326-33. · 3.36 Impact Factor
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Ester Mejstríková,
Eva Fronková,
Tomás Kalina,
Marek Omelka,
Drago Batinić,
Klara Dubravcić,
Klára Pospísilová,
Martina Vásková,
Drorit Luria, Suk Hang Cheng,
Margaret Ng,
Yonna Leung,
Janos Kappelmayer,
Flora Kiss,
Shai Izraeli,
Batia Stark,
Martin Schrappe,
Jan Trka,
Jan Starý,
Ondrej Hrusák
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ABSTRACT: Residual disease (RD) is an important prognostic factor in acute lymphoblastic leukemia (ALL). Flow cytometry (FC)-based RD detection is easy to perform, but interpretation requires expert analysis due to individual differences among patients.
We focused at the design of standardized and reproducible RD monitoring in ALL. RD was investigated by a uniform gating strategy, which was designed internationally and tested in one center by Ig/TCR rearrangements.
For each gate, positivity cutoff value was assigned using quantification of non-leukemic background. Comparing to Ig/TCR at 0.1% level, 80 of 103 specimens were correctly diagnosed by FC. The predictive value of FC RD at day 15 was then analyzed. In B lineage ALL, day 15 FC significantly correlated with Ig/TCR results at day 33 and/or week 12 (P < 0.01). No significant correlation was found in T lineage ALL.
Thus, FC with preset uniform gating at day 15 predicts PCR-detectable MRD in B precursor ALL. Presented data may be used to define new polychromatic cytometric diagnostics of MRD including semiautomatic assessment. Pediatr Blood Cancer 2010; 54:62-70. (c) 2009 Wiley-Liss, Inc.
Pediatric Blood & Cancer 09/2009; 54(1):62-70. · 1.89 Impact Factor
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ABSTRACT: Despite the demonstrated constitutive activation of NF-kappaB in nasopharyngeal carcinoma (NPC), the therapeutic potential of targeting this pathway has not been investigated. Here, we employed a small molecule inhibitor of NF-kappaB, DHMEQ (which mainly blocks nuclear translocation of activated NF-kappaB) and demonstrated significant inhibition of NPC cell proliferation, migration, invasion, as well as anchorage-independent growth. These antitumor effects were associated with induction of G(2)/M cell cycle arrest and apoptosis, and downregulation of NF-kappaB target genes (EGFR, cyclin D1 and survivin). This first demonstration of therapeutic benefits of NF-kappaB targeting in NPC implicates the importance of targeting this pathway in NPC.
Cancer letters 07/2009; 287(1):23-32. · 4.86 Impact Factor
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ABSTRACT: Severe and potentially fatal hypersensitivity reactions to drugs, particularly antiepileptics, are clinically unpredictable. Recent evidence has revealed a strong and specific association between the implicated drug, the type of adverse reaction, and the particular HLA genotype. An urgent need exists for rapid diagnosis of HLA status to guide drug prescription; however, traditional HLA genotyping has a long turnaround time, is expensive, and is available only in specialized centers. We tested the feasibility of the loop-mediated isothermal amplification (LAMP)-based approach to detect a specific HLA genotype. As an example, we used B*1502, an HLA allele strongly associated with carbamazepine-induced Stevens-Johnson syndrome/toxic epidermal necrolysis, and validated the assay's application as a simple, accurate, rapid, and low-cost blood test for use in both clinical and bedside settings.
We evaluated B*1502 status with the new LAMP method and compared the results with those obtained by sequence-based typing (SBT) (n = 250) and by sequence-specific primer PCR (SSP-PCR) (n = 200) for 450 samples of DNA (n = 50) and blood (n = 400) from a hematology laboratory.
LAMP results showed 100% concordance with both SBT and SSP-PCR results, confirming that LAMP detection of a specific HLA genotype (B*1502 in this case) is an accurate method. All results were available within 1 h.
Our study confirmed that the new LAMP method for detecting a specific HLA genotype is simple, inexpensive, accurate, and rapid, and may be of help in overcoming barriers in effective clinical practice.
Clinical Chemistry 07/2009; 55(8):1568-72. · 7.91 Impact Factor
