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ABSTRACT: Nasopharyngeal carcinoma (NPC) is a cancer with its highest prevalence among the southern Chinese and is rare elsewhere in the world. The main treatment modalities include chemotherapy and radiotherapy. However, tumor chemoresistance often limits the efficacy of NPC treatment and reduces survival rates. Thus, identifying new selective chemotherapeutic drugs for NPC treatment is needed. In this current study, the anti-tumor efficacy of a polo-like kinase inhibitor, Ro5203280, was investigated. Ro5203280 induces tumor suppression both in vitro and in vivo. An inhibitory effect was observed with the highly proliferating cancer cell lines tested, but not with the non-tumorigenic cell line. Real-time cell proliferation and FACS analysis, together with immunohistochemical (IHC), immunofluorescence (IF), and Annexin V staining assays were used to evaluate the impact of drug treatment on cell cycle and apoptosis. Ro5203280 induces G2/M cell cycle arrest and apoptosis. Western blotting shows it inhibits PLK1 phosphorylation and down-regulates the downstream signaling molecule, Cdc25c, and up-regulates two important mitosis regulators, Wee1 and Securin, as well as the DNA damage-related factor Chk2 in vitro and in vivo. In vivo tumorigenicity assays with Ro5203280 intravenous injection demonstrated its potent ability to inhibit tumor growth in mice, with no observable signs of toxicity. These findings suggest the potential usefulness of Ro5203280 as a chemotherapeutic targeting drug for NPC treatment.
Molecular Cancer Therapeutics 05/2013; · 5.23 Impact Factor
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Xing-Sheng Shu,
Lili Li,
Mingfang Ji,
Yingduan Cheng,
Jianming Ying,
Yichao Fan,
Lan Zhong,
Xiaodong Liu, Sai Wah Tsao,
Anthony Tc Chan,
Qian Tao
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ABSTRACT: Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV)-associated tumor prevalent in Southern China and Southeast Asia, with the 3p14-12 locus reported as a critical tumor suppressor gene (TSG) region during its pathogenesis. We identified a novel 3p14.2 TSG, FEZF2 (FEZ family zinc finger 2), for NPC. FEZF2 is readily expressed in normal tissues including upper respiratory epithelium, testis, brain and ovary tissues as well as immortalized nasopharyngeal epithelial cell line NP69, but completely silenced in NPC cell lines due to CpG methylation of its promoter, although no homozygous deletion of FEZF2 was detected. Aza treatment restored FEZF2 expression in NPC cell lines along with its promoter demethylation. FEZF2 was frequently downregulated in NPC tumors, with promoter methylation detected in 75.5% of tumors, but only in 7.1% of normal nasopharyngeal tissues. Restored FEZF2 expression suppressed NPC cell clonogenicity through inducing G2/M cell cycle arrest and apoptosis, and also inhibited NPC cell migration and stemness. FEZF2 acted as a HDAC-associated repressor downregulating multiple oncogenes including EZH2 and MDM2, through direct binding to their promoters. Concomitantly, overexpression of EZH2 was frequently detected in NPC tumors. Thus, we have identified FEZF2 as a novel 3p14.2 TSG frequently inactivated by promoter methylation in NPC, which functions as a repressor downregulating multiple oncogene expression.
Carcinogenesis 05/2013; · 5.70 Impact Factor
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Ming-Chu Lo,
Tak-Chun Yip,
Kai-Cheong Ngan,
Wai-Wai Cheng,
Chun-Key Law,
Pui-Shan Chan,
King-Chi Chan,
Kong-Chu Wong,
Ngok-Shun Wong,
Kwok-Wai Lo,
Wai-Tong Ng,
Wing-Mui Lee, Sai-Wah Tsao,
Lai-Wan Kwong,
Maria Li Lung,
Nai-Ki Mak
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ABSTRACT: Macrophage migration inhibitory factor (MIF) and CXCL8 (also named IL-8) are strongly expressed in the tissues of nasopharyngeal carcinoma (NPC). However, their role in the growth of NPC has not been fully examined. This study aims to evaluate the functions of MIF and CXCL8 on the growth of NPC tumor spheres. The elevated expression of CXCL8 in tumor over normal tissues was confirmed in 37 pairs of biopsies from NPC patients. In the in vitro study, all the poorly differentiated NPC cell lines, including the EBV-positive C666-1, and the EBV-negative CNE-1, CNE-2, SUNE-1, HNE-1 and HONE-1 cells, were found to express CXCL8 and MIF. Therefore, the EBV-positive C666-1 cell was selected to examine for the role of MIF and CXCL8 in the growth of the NPC tumor spheres. Functional study showed that the growth of C666-1 tumor spheres, under the nutrient poor or growth factor supplemented culture conditions, could be inhibited by the CXCL8 specific peptide inhibitor. The growth of the tumor spheres could also be reduced by the CXCR2 specific inhibitor SB225002 or the PI3K/AKT inhibitor LY294002, indicating that the endogenously produced CXCL8 plays an autocrine role in the growth of the tumor spheres. Further mechanistic studies revealed that the gene expression of CXCL8 could be reduced by the MIF specific small interfering RNA (siRNA) or NF-κB inhibitor parthenolide, and the growth of tumor spheres was also reduced after MIF siRNA transfection. Taken together, the present study highlights the role of MIF/CXCL8/CXCR2 axis in the growth of NPC tumor spheres. Chemotherapeutic interference of this signaling pathway may help to control the growth of the NPC tumor.
Cancer letters 02/2013; · 4.86 Impact Factor
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Kwan Ho Tang,
Yongdong Dai,
Man Tong,
Yuen-Piu Chan,
Pak Shing Kwan,
Li Fu,
Yan-Ru Qin, Sai Wah Tsao,
Hong Lok Lung,
Maria Li Lung,
Daniel K Tong,
Simon Law,
Kwok Wah Chan,
Stephanie Ma,
Xin-Yuan Guan
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ABSTRACT: Tumor-initiating cells (TICs), also known as cancer stem cells, are regarded widely as a specific subpopulation of cells needed for cancer initiation and progression. TICs have yet to be identified in esophageal tumors that have a rising incidence in developed countries. Here we report a CD90+ cell population found in esophageal squamous cell carcinoma (ESCC) which is endowed with stem cell-like properties and high tumorigenic and metastatic potential. mRNA profiling of these cells suggested pathways through which they drive tumor growth and metastasis, with deregulation of an Ets1-MMP signaling pathway and epithelial-mesenchymal transition figuring prominently. These cells possessed higher self-renewal activity and were sufficient for tumor growth, differentiation, metastasis and chemotherapeutic resistance. CD90+ TICs were isolated and characterized from ESCC clinical specimens as well as ESCC cell lines. In freshly resected clinical specimens, they represented a rare cell population the levels of which correlated with strong family histories and lymph node metastasis. Our results prompt further study of this CD90+ population of esophageal TICs as potential therapeutic targets.
Cancer Research 02/2013; · 7.86 Impact Factor
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Guitao Zhang,
Chi Man Tsang,
Wen Deng,
Yim Ling Yip,
Vivian Wai-Yan Lui,
Sze Chuen Cesar Wong,
Annie Lai-Man Cheung,
Pok Man Hau,
Musheng Zeng,
Maria Li Lung,
Honglin Chen,
Kwok Wai Lo,
Kenzo Takada, Sai Wah Tsao
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ABSTRACT: Nasopharyngeal carcinoma (NPC) is etiologically associated with Epstein-Barr virus (EBV) infection. However, the exact role of EBV in NPC pathogenesis remains elusive. Activation of signal transducer and activator of transcription 3 (STAT3) is common in human cancers including NPC and plays an important role in the pathogenesis and progression of human cancers. Interleukin-6 (IL-6), a major inflammatory cytokine, is a potent activator of STAT3. In this study, we report that EBV-infected immortalized nasopharyngeal epithelial (NPE) cells often acquire an enhanced response to IL-6-induced STAT3 activation to promote their growth and invasive properties. Interestingly, this enhanced IL-6/STAT3 response was mediated by overexpression of IL-6 receptor (IL-6R). Furthermore, IL-6R overexpression enhanced IL-6-induced STAT3 activation in uninfected immortalized NPE cells in vitro, and promoted growth and tumorigenicity of EBV-positive NPC cell line (C666-1) in vivo. Moreover, it is shown for the first time that IL-6R was overexpressed in clinical specimens of NPC. IL-6 expression could also be strongly detected in the stromal cells of NPC and a higher circulating level of IL-6 was found in the sera of advance-staged NPC patients compared to the control subjects. Therefore, IL-6R overexpression, coupled with enhanced IL-6/STAT3 signaling may facilitate the malignant transformation of EBV-infected premalignant NPE cells into cancer cells, and enhance malignant properties of NPC cells.
PLoS ONE 01/2013; 8(5):e62284. · 4.09 Impact Factor
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ABSTRACT: Latent infection with Epstein-Barr virus (EBV) is associated with several types of malignancies including nasopharyngeal carcinoma (NPC), which is particularly more prevalent in Southern China. EBV expresses at least 44 mature microRNAs (miRNAs) to modulate the activity of viral and cellular RNAs, but the targets of these EBV-encoded miRNAs in NPC are not well understood. In this report, we characterized DICE1 tumor suppressor to be a cellular target of EBV miR-BART3* miRNA. miR-BART3* was abundantly expressed in NPC cells. The target site of miR-BART3* located in the 3?-untranslated region of DICE1 transcript was identified and characterized. Enforced expression of miR-BART3* or its precursor pre-miR-BART3 led to down-regulation of endogenous DICE1 expression. Inhibition of endogenous miR-BART3* in NPC cells with anti-miR-BART3* oligonucleotide inhibitor resulted in increased expression of DICE1 protein. On the contrary, expression of miR-BART3* overcame the growth suppressive activity of DICE1 and stimulated cell proliferation. Consistent with its tumor suppressive function, DICE1 was underexpressed in EBV-expressing NPC tumor tissues. Taken together, our findings suggest that EBV encoded miR-BART3* miRNA targets DICE1 tumor suppressor to promote cellular growth and transformation in NPC. © 2012 Wiley Periodicals, Inc.
International Journal of Cancer 12/2012; · 5.44 Impact Factor
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ABSTRACT: Nasopharyngeal carcinoma (NPC), an endemic head and neck cancer found in Southeast Asia, is etiologically associated with the infection of an oncogenic virus, the Epstein-Barr virus (EBV). Here, we review literature findings on the potential/putative role of STAT3 signaling in its pathogenesis and discuss anti-STAT3 targeting as a therapeutic and possibly prevention strategy for NPC. Lastly, the potential involvement of STAT3 in other oncovirus-associated (e.g. the human papillomavirus) head and neck cancers have not been investigated and we hope that findings in EBV-associated NPC can prompt future investigations in these cancers, which are of increasing impact in the Western countries.
Cancer letters 12/2012; · 4.86 Impact Factor
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ABSTRACT: BACKGROUND: Nasopharyngeal carcinomas (NPC) are consistently associated with the Epstein-Barr virus (EBV). Though NPCs are more radiosensitive and chemosensitive than other tumors of the upper aero-digestive tract, many therapeutic challenges remain. In a previous report, we have presented data supporting a possible therapeutic strategy based on artificial TLR3 stimulation combined to the inhibition of the IAP protein family (Inhibitor of Apoptosis Proteins). The present study was designed to progress towards practical applications of this strategy pursuing 2 main objectives: 1) to formally demonstrate expression of the TLR3 protein by malignant NPC cells; 2) to investigate the effect of poly(A:U) as a novel TLR3-agonist more specific than poly(I:C) which was used in our previous study. METHODS: TLR3 expression was investigated in a series of NPC cell lines and clinical specimens by Western blot analysis and immunohistochemistry, respectively. The effects on NPC cells growth of the TLR3 ligand poly(A:U) used either alone or in combination with RMT5265, an IAP inhibitor based on Smac-mimicry, were assessed using MTT assays and clonogenic assays. RESULTS: TLR3 was detected at a high level in all NPC cell lines and clinical specimens. Low concentrations of poly(A:U) were applied to several types of NPC cells including cells from the C17 xenograft which for the first time have been adapted to permanent propagation in vitro. As a single agent, poly(A:U) had no significant effects on cell growth and cell survival. In contrast, dramatic effects were obtained when it was combined with the IAP inhibitor RMT5265. These effects were obtained using concentrations as low as 0.5 mug/ml (poly(A:U)) and 50 nM (RMT5265). CONCLUSION: These data confirm that TLR3 expression is a factor of vulnerability for NPC cells. They suggest that in some specific pathological and pharmacological contexts, it might be worth to use Smac-mimetics at very low doses, allowing a better management of secondary effects. In light of our observations, combined use of both types of compounds should be considered for treatment of nasopharyngeal carcinomas.
Infectious Agents and Cancer 12/2012; 7(1):36.
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Chi Man Tsang,
Yim Ling Yip,
Kwok Wai Lo,
Wen Deng,
Ka Fai To,
Pok Man Hau,
Victoria Ming Yi Lau,
Kenzo Takada,
Vivian Wai Yan Lui,
Maria Li Lung,
Honglin Chen,
Musheng Zeng,
Jaap Michiel Middeldorp,
Annie Lai-Man Cheung, Sai Wah Tsao
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ABSTRACT: Undifferentiated nasopharyngeal carcinomas (NPCs) are commonly present with latent EBV infection. However, events regulating EBV infection at early stages of the disease and the role of EBV in disease pathogenesis are largely undefined. Genetic alterations leading to activation of cyclin D1 signaling in premalignant nasopharyngeal epithelial (NPE) cells have been postulated to predispose cells to EBV infection. We previously reported that loss of p16, a negative regulator of cyclin D1 signaling, is a frequent feature of NPC tumors. Here, we report that early premalignant lesions of nasopharyngeal epithelium overexpress cyclin D1. Furthermore, overexpression of cyclin D1 is closely associated with EBV infection. Therefore we investigated the potential role of cyclin D1 overexpression in dysplastic NPE cells in vitro. In human telomerase reverse transcriptase-immortalized NPE cells, overexpression of cyclin D1 or a p16-resistant form of CDK4 (CDK4(R24C)) suppressed differentiation. This suppression may have implications for the close association of EBV infection with undifferentiated NPC. In these in vitro models, we found that cellular growth arrest and senescence occurred in EBV-infected cell populations immediately after infection. Nevertheless, overexpression of cyclin D1 or a p16-resistant form of CDK4 or knockdown of p16 in the human telomerase reverse transcriptase-immortalized NPE cell lines could counteract the EBV-induced growth arrest and senescence. We conclude that dysregulated expression of cyclin D1 in NPE cells may contribute to NPC pathogenesis by enabling persistent infection of EBV.
Proceedings of the National Academy of Sciences 11/2012; · 9.68 Impact Factor
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Li-Yi Zhang,
Victor Ho-Fun Lee,
Alissa Michelle Go Wong,
Dora Lai-Wan Kwong,
Ying-Hui Zhu,
Sui-Sui Dong,
Kar-Lok Kong,
Juan Chen, Sai-Wah Tsao,
Xin-Yuan Guan,
Li Fu
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ABSTRACT: Nasopharyngeal carcinoma (NPC) is a type of head and neck cancer with significantly high prevalence in Southern China. Unlike other head and neck cancers, mutations or deletions of tumor suppressor genes (TSGs) in NPC are not common. Recently, down-regulation of TSGs expression by microRNA (miRNA) is increasingly recognized as an important mechanism of nasopharyngeal tumorigenesis. In this study, we reported that microRNA-144 (miR-144) was frequently up-regulated in NPC specimens and cell lines. Repression of miR-144 significantly decreased cell proliferation, clonogenicity, migration, invasion and tumor formation in nude mice, while restoring miR-144 in miR-144 attenuated NPC cells exhibited a strong tumorigenic role. Further, we found that miR-144 was inversely correlated with the tumor suppressor gene Phosphatase and tensin homolog (PTEN) in NPC specimens and cell lines, and then we identified PTEN as a direct target of miR-144 in NPC cell lines. PTEN down-regulation in miR-144 attenuated cells could increase cell growth, migration and invasion. Mechanistic investigations revealed that miR-144 suppressed the expression of PTEN to increase the expression of pAkt and cyclin D1 to promote G1-phase transition and decrease E-cadherin to promote migration and invasion. Taken together, we provide compelling evidence that miR-144 functions as an onco-miRNA in NPC, and its onco-effects are mediated chiefly by repressing PTEN expression to activate the PI3K/Akt pathway.
Carcinogenesis 11/2012; · 5.70 Impact Factor
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Han Chen,
Josephine Mun Yee Ko,
Victor Chun Lam Wong,
Marko Hyytiainen,
Jorma Keski-Oja,
Daniel Chua,
John M Nicholls,
Florence Man Fung Cheung,
Anne Wing Mui Lee,
Dora Lai-Wan Kwong,
Pui Man Chiu,
Eugene R Zabarovsky, Sai Wah Tsao,
Qian Tao,
Rebecca Kan,
Stephen Ho Kin Chan,
Eric J Stanbridge,
Maria Li Lung
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ABSTRACT: This study identified LTBP-2 as a pleiotropic tumor suppressor in nasopharyngeal carcinoma, which safeguards against critical malignant behaviors of tumor cells. LTBP-2 expression was significantly decreased or lost in up to 100% of NPC cell lines (7/7) and 80% of biopsies (24/30). Promoter hypermethylation was found to be involved in LTBP-2 silencing. Using a tetracycline-regulated inducible expression system, we unveiled functional roles of LTBP-2 in suppressing colony formation, anchorage-independent growth, cell migration, angiogenesis, VEGF secretion, and tumorigenicity. Three-dimensional culture studies suggested the involvement of LTBP-2 in maintenance of tumor cell dormancy in a growth factor favorable microenvironment.
Cancer letters 06/2012; 325(1):89-98. · 4.86 Impact Factor
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Stephanie Ma,
Jessie Y J Bao,
Pak Shing Kwan,
Yuen Piu Chan,
Carol M Tong,
Li Fu,
Na Zhang,
Amy H Y Tong,
Yan-Ru Qin, Sai Wah Tsao,
Kwok Wah Chan,
Si Lok,
Xin-Yuan Guan
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ABSTRACT: Esophageal squamous cell carcinoma (ESCC) is the most commonly observed histologic subtype of esophageal cancer. ESCC is believed to develop via accumulation of numerous genetic alterations, including inactivation of tumor suppressor genes and activation of oncogenes. We searched for transcripts that were altered in human ESCC samples compared with nontumor tissues.
We performed integrative transcriptome sequencing (RNA-Seq) analysis using ESCC samples from 3 patients and adjacent nontumor tissues to identify transcripts that were altered in ESCC tissue. We performed molecular and functional studies of the transcripts identified and investigated the mechanisms of alteration.
We identified protein tyrosine kinase 6 (PTK6) as a transcript that was significantly down-regulated in ESCC tissues and cell lines compared with nontumor tissues or immortalized normal esophageal cell lines. The promoter of the PTK6 gene was inactivated in ESCC tissues at least in part via hypermethylation and histone deacetylation. Knockdown of PTK6 in KYSE30 ESCC cells using small hairpin RNAs increased their ability to form foci, migrate, and invade extracellular matrix in culture and form tumors in nude mice. Overexpression of PTK6 in these cells reduced their proliferation in culture and tumor formation in mice. PTK6 reduced phosphorylation of Akt and glycogen synthase kinase (GSK)3β, leading to activation of β-catenin.
PTK6 was identified as a transcript that is down-regulated in human ESCC tissues via epigenetic modification at the PTK6 locus. Its product appears to regulate cell proliferation by reducing phosphorylation of Akt and GSK3β, leading to activation of β-catenin. Reduced levels of PTK6 promote growth of xenograft tumors in mice; it might be developed as a marker of ESCC.
Gastroenterology 06/2012; 143(3):675-86.e1-12. · 11.68 Impact Factor
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Marco K C Hui,
Kenneth K Y Lai,
Kwok Wah Chan,
John M Luk,
Nikki P Lee,
Yvonne Chung,
Leo C M Cheung,
Gopesh Srivastava, Sai Wah Tsao,
Johnny C Tang,
Simon Law
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ABSTRACT: To examine the correlation of survivin (both total and nuclear survivin) with clinicopathological parameters of esophageal squamous cell carcinoma (ESCC) patients. Tumors and non-tumor tissues near the proximal resection margins were resected from ESCC patients undergone esophagectomy. Quantitative polymerase chain reaction (qPCR) was performed to detect survivin mRNA expression level in the 10 paired tumor and adjacent non-tumor tissues. To confirm with the clinical situation, survivin mRNA and protein expression were measured by qPCR and immunoblot, respectively, in 5 ESCC cell lines and a non-neoplastic esophageal epithelial cell line. Immunohistochemistry was employed to reveal the cellular localization of survivin in tumor tissues isolated from the 64 ESCC patients undergone surgery alone. Up-regulation of survivin mRNA and protein was found in 5 ESCC lines (HKESC-1, HKESC-2, HKESC-3, HKESC-4, and SLMT-1) when compared to a non-neoplastic esophageal epithelial cell line NE-1. In particular, HKESC-3, HKESC-4, and SLMT-1 cells demonstrated ~50-fold increase in survivin mRNA. High level of survivin mRNA in tumor tissues when compared to non-tumor tissues was found in 70 % (7 of 10) of clinical cases. The increase in expression ranged from ~twofold to ~16-fold. Immunohistochemistry results showed that survivin was found at the cell nuclei in all specimens examined. Nuclear expression of survivin was inversely associated with the likelihood of developing nodal metastasis (p = 0.021) and significantly associated with early-stage ESCC (p = 0.039). Nuclear survivin could serve as a marker for indicating disease status in ESCC patients.
Medical Oncology 04/2012; · 2.14 Impact Factor
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ABSTRACT: EBV-associated human malignancies may originate from B cells and epithelial cells. EBV readily infects B cells in vitro and transforms them into proliferative lymphoblastoid cell lines. In contrast, infection of human epithelial cells in vitro with EBV has been difficult to achieve. The lack of experimental human epithelial cell systems for EBV infection has hampered the understanding of biology of EBV infection in epithelial cells. The recent success to infect human epithelial cells with EBV in vitro has allowed systematic investigations into routes of EBV entry, regulation of latent and lytic EBV infection, and persistence of EBV infection in infected epithelial cells. Understanding the biology of EBV infection in human epithelial cells will provide important insights to the role of EBV infection in the pathogenesis of EBV-associated epithelial malignancies including nasopharyngeal carcinoma and gastric carcinoma.
Seminars in Cancer Biology 04/2012; 22(2):137-43. · 6.47 Impact Factor
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Yuen-Keng Ng,
Elaine Yue Ling Wong,
Cecilia Pik Yuk Lau,
Jessica Pui Lan Chan,
Sze Chuen Cesar Wong,
Andrew Sai-Kit Chan,
Maggie Pui Chun Kwan, Sai-Wah Tsao,
Chi-Man Tsang,
Paul Bo San Lai,
Anthony Tak Cheung Chan,
Vivian Wai Yan Lui
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ABSTRACT: Recent studies revealed an unexpected role of the neurotrophin receptor pathway, BDNF/TrkB signaling, in cancer metastasis and anoikis (i.e. detachment-induced cell death). Survival of cancer cells in detached state (known as anoikis-resistance) is known to be pre-requisite for metastasis. Nasopharyngeal carcinoma (NPC), an endemic head and neck cancer in Southeast Asia, is highly invasive, metastatic, and etiologically associated with Epstein-Barr virus (EBV, an oncovirus) infection. Mechanistic studies on the invasive/metastatic nature of NPC can facilitate the development of anti-metastatic therapy in NPC. Thus far, the role of BDNF/TrkB signaling in virus-associated human cancer is unclear. Here, using multiple cell line models of NPC with EBV-association (HONE-1-EBV, HK1-LMP1 and C666-1), we investigated the potential involvement of BDNF/TrkB signaling in cellular migration and anoikis-resistant characteristics of NPC. We found that all three EBV-associated NPC cell lines tested were intrinsically anoikis-resistant (i.e. survived in detached state) and expressed both BDNF and TrkB. BDNF stimulation induced cellular migration, but not proliferation of these cells. Further, we examined if pharmacologic targeting of anoikis-resistance of NPC cells can be achievable by a proof-of-concept Trk inhibitor, K252a, in these EBV-associated NPC models. Our results demonstrated that K252a, was able to attenuate BDNF-induced migration and proliferation of NPC cells. More importantly, we demonstrated for the first time that K252a harbored potent anoikis-sensitization activity (i.e. sensitizing cancer cells to detachment-induced cell death) against EBV-associated human cancer cells, namely NPC cells. This proof-of-concept study demonstrated that K252a, a Trk inhibitor, can potentially be used as an anoikis-sensitizing agent in NPC.
Investigational New Drugs 02/2012; 30(1):48-58. · 3.36 Impact Factor
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Cheuk-Him Man,
Samantha Wei-Man Lun,
Jan Wai-Ying Hui,
Ka-Fai To,
Kwong-Wai Choy,
Anthony Wing-Hung Chan,
Chit Chow,
Grace Tin-Yun Chung, Sai-Wah Tsao,
Timothy Tak-Chun Yip,
Pierre Busson,
Kwok-Wai Lo
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ABSTRACT: Nasopharyngeal carcinoma (NPC) is an EBV-associated epithelial malignancy which is prevalent in south-east Asia and southern China. Despite the multiple genetic and epigenetic changes reported, the contribution of dysregulated signalling pathways to this distinct type of head and neck cancer is not well understood. Here we demonstrate the up-regulation of NOTCH ligands (JAG1 or DLL4) and effector (HEY1) in the majority of EBV-positive tumour lines and primary tumours. Among the NOTCH receptors, NOTCH3 was over-expressed in all EBV-positive tumour lines and 92.5% of primary tumours. Aberrant activation of NOTCH3 signalling was consistently detected in all these samples. These findings imply that NOTCH3 may play an crucial role in the development of NPC. By NOTCH3 specific siRNA, NOTCH3 signalling was suppressed and thereby significant growth inhibition and apoptosis induction occurred in NPC cells. Down-regulation of a number of targets involved in cell proliferation, eg CCND1, C-MYC,NFKB1, and survival, eg BCL2, BCL-XL, SURVIVIN, was confirmed in the NOTCH3 knockdown NPC cells. Importantly, NOTCH3 knockdown highly enhanced the sensitivity of NPC cells to cisplatin treatment. Furthermore, we revealed that the ability of NPC cells to form spheroids in vitro and tumours in nude mice was also significantly decreased after knockdown of NICD3 expression. These findings indicate that activation of NOTCH3 pathway is a critical oncogenic event in NPC tumourigenesis. Targeting NOTCH3 signalling may serve as a potential therapeutic approach for treating patients suffering from EBV-associated NPC.
The Journal of Pathology 02/2012; 226(3):471-81. · 6.32 Impact Factor
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ABSTRACT: Esophageal cancer is a deadly cancer with esophageal squamous cell carcinoma (ESCC) as the major type. Until now there has been a lack of reliable prognostic markers for this malignancy. This study aims to investigate the clinical correlation between Forkhead box M1 (FoxM1)and patients' parameters in ESCC.
Immunohistochemistry was performed to investigate the expression and localization of FoxM1 in 64ESCC tissues and 10 nontumor esophageal tissues randomly selected from 64 patients before these data were used for clinical correlations.
Cytoplasmic and nuclear expressions of FoxM1 were found in 63 and 16 of the 64 ESCC tissues, respectively.Low cytoplasmic expression of FoxM1 was correlated with early pathological stage in ESCC (P = 0.018),while patients with nuclear FoxM1 were younger in age than those without nuclear expression (P\0.001).Upregulation of FoxM1 mRNA was found in five ESCCcell lines (HKESC-1, HKESC-2, HKESC-3, HKESC-4,and SLMT-1) when compared to non-neoplastic esophageal squamous cell line NE-1 using quantitative polymerase chain reaction (qPCR). Except for HKESC-3, all studied ESCC cell lines demonstrated a high expression of FoxM1 protein using immunoblot. A high mRNA level of FoxM1 was observed in all of the ESCC tissues examined when compared to their adjacent nontumor tissues using qPCR.
Cytoplasmic FoxM1 was correlated with pathological stage and might be a biomarker for advanced ESCC.
World Journal of Surgery 01/2012; 36(1):90-7. · 2.36 Impact Factor
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ABSTRACT: Nasopharyngeal carcinoma (NPC) is a common cancer in Southeast Asia, particularly in southern regions of China. EBV infection is closely associated with NPC and has long been postulated to play an etiological role in the development of NPC. However, the role of EBV in malignant transformation of nasopharyngeal epithelial cells remains enigmatic. The current hypothesis of NPC development is that premalignant nasopharyngeal epithelial cells harboring genetic alterations support EBV infection and expression of EBV genes induces further genomic instability to facilitate the development of NPC. The latent membrane protein 1 (LMP1) is a well-documented EBV-encoded oncogene. The involvement of LMP1 in human epithelial malignancies has been implicated, but the mechanisms of oncogenic actions of LMP1, particularly in nasopharyngeal cells, are unclear. Here we observed that LMP1 expression in nasopharyngeal epithelial cells impaired G2 checkpoint, leading to formation of unrepaired chromatid breaks in metaphases after γ-ray irradiation. We further found that defective Chk1 activation was involved in the induction of G2 checkpoint defect in LMP1-expressing nasopharyngeal epithelial cells. Impairment of G2 checkpoint could result in loss of the acentrically broken chromatids and propagation of broken centric chromatids in daughter cells exiting mitosis, which facilitates chromosome instability. Our findings suggest that LMP1 expression facilitates genomic instability in cells under genotoxic stress. Elucidation of the mechanisms involved in LMP1-induced genomic instability in nasopharyngeal epithelial cells will shed lights on the understanding of role of EBV infection in NPC development.
PLoS ONE 01/2012; 7(6):e39095. · 4.09 Impact Factor
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ABSTRACT: Hepatocellular carcinoma is one of the most malignant human cancers with high metastatic potential. The aim of this study is to investigate the anti-metastatic effect of genipin and its underlying mechanism.
The anti-metastatic potential of genipin was evaluated by both cell and animal model. Wound healing and invasion chamber assays were introduced to examine the anti-migration and anti-invasion action of genipin in human hepatocellular carcinoma cell HepG2 and MHCC97L; orthotopical implantation model was used for in vivo evaluation. Gelatin Zymography, Immunoblotting, quantitative real-time polymerase chain reaction and ELISA assays were used to study the mechanisms underlying genipin's anti-metastatic effect.
Genipin suppresses the motility and invasiveness of HepG2 and MHCC97L at non-toxic doses, which may be correlated to the inhibition of genipin on MMP-2 activities in the cells. No significant reduced expression of MMP-2 was observed either at mRNA or at protein level. Furthermore, genipin could specifically up-regulate the expression of TIMP-1, the endogenous inhibitor of MMP-2 activities. Silencing of TIMP-1 by RNA interference abolishes genipin's anti-metastaic effect. Activation of p38 MAPK signaling was observed in genipin-treated cells, which is responsible for the TIMP-1 overexpression and MMP-2 inhibition. Presence of SB202190, the p38 MAPK inhibitor, attenuates the anti-metastatic potential of genipin in hepatocellular carcinoma. Orthotopical implantation model showed that genipin could suppress the intrahepatic metastatic as well as tumor expansion in liver without exhibiting potent toxicity.
Our findings demonstrated the potential of genipin in suppressing hepatocellular carcinoma metastasis, and p38/TIMP-1/MMP-2 pathway may be involved as the key mechanism of its anti-metastasis effect.
PLoS ONE 01/2012; 7(9):e46318. · 4.09 Impact Factor
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ABSTRACT: Chromosomal instability is the major form of genomic instability in cancer cells. Amongst various forms of chromosomal instability, pericentromeric or centromeric instability remains particularly poorly understood. In the present study, we found that pericentromeric instability, evidenced by dynamic formation of pericentromeric or centromeric rearrangements, breaks, deletions or iso-chromosomes, was a general phenomenon in human cells immortalized by expression of human papillomavirus type 16 E6 and E7 (HPV16 E6E7). In particular, for the first time, we surprisingly found a dramatic increase in the proportion of pericentromeric chromosomal aberrations relative to total aberrations in HPV16 E6E7-expressing cells 72 h after release from aphidicolin (APH)-induced replication stress, with pericentromeric chromosomal aberrations becoming the predominant type of structural aberrations (∼70% of total aberrations). In contrast, pericentromeric aberrations accounted for only about 20% of total aberrations in cells at the end of APH treatment. This increase in relative proportion of pericentromeric aberrations after release from APH treatment revealed that pericentromeric breaks induced by replication stress are refractory to prompt repair in HPV16 E6E7-expressing epithelial cells. Telomerase-immortalized epithelial cells without HPV16 E6E7 expression did not exhibit such preferential pericentromeric instability after release from APH treatment. Cancer development is often associated with replication stress. Since HPV16 E6 and E7 inactivate p53 and Rb, and p53 and Rb pathway defects are common in cancer, our finding that pericentromeric regions are refractory to prompt repair after replication stress-induced breakage in HPV16 E6E7-expressing cells may shed light on mechanism of general pericentromeric instability in cancer.
PLoS ONE 01/2012; 7(10):e48576. · 4.09 Impact Factor
