Hippo pathway contributes to cisplatin resistant-induced EMT in nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is a kind of head-neck malignant tumor derived from the nasopharyngeal epithelium and is mainly prevalent in Southern China and Southeast Asia countries. Cisplatin (DDP) provides the first-line therapeutic administration in NPC patients. However, chemoresistance has been a main barrier and caused bad treatment outcome in NPC therapy. To understand the molecular mechanism of acquired resistance to DDP, multiple methods were performed to examine the morphocytology and molecular changes in DDP-resistant NPC cells. We found that drug resistance cells displayed epithelial-mesenchymal transition (EMT) characteristics. DDP-resistant NPC cells exhibited enhanced migration and invasion potential. Moreover, overexpression of TAZ, one key gene in Hippo pathway, is closely associated with the DDP resistance of NPC cells and its EMT properties. Depletion of TAZ in DDP-resistant cells reversed EMT phenotypes to MET characteristics and restored chemosensitivity of DDP-resistant cells to DDP treatment. These results suggest that inactivation of TAZ could be a promising approach for the treatment of NPC patients.     

Small molecule inhibitor TW-37 is tolerable and synergistic with chemotherapy in nasopharyngeal carcinoma

Chemotherapy is a crucial adjuvant therapy of advanced nasopharyngeal carcinoma (NPC). However, enhancing sensitivity and tolerance of chemotherapeutics in NPC treatment have been challenging. Both Bcl-2 and Mcl-1, 2 pro-survival proteins of Bcl-2 family, play essential roles on the chemotherapy tolerance of numerous cancers. In the present study, we explored the influences of TW-37, a small molecule inhibitor of Bcl-2 and Mcl-1, on the efficiency of chemotherapy for NPC. Oncomine cancer database shows that NPC tissues have higher expression of Bcl-2 and Mcl-1 than those of normal nasopharyngeal epithelial (NPE) tissues. And our results reveal that chemotherapeutics, Cisplatin (CDDP) and 5-Fluoracil (5-FU), result in the greater decrease of protein level of Bcl-2 and Mcl-1 in NPC cells than those in NPE cells. TW-37 does not have significant impact on the chemotherapeutics-treated NPE cell viability at a dosage that efficiently reduces chemotherapeutics-treated NPC cell viability. Moreover, impacts of TW-37 on the cell viability of chemotherapeutics-treated NPC cells are dependent on the expression of Bcl-2 and Mcl-1 in NPC cells. Further explorations suggest that TW-37 prominently promotes apoptosis in NPC cells under chemotherapeutics treatments but not in NPE cells. Meanwhile, TW-37 also remarkably reduces colony formation ability of chemotherapeutics-treated NPC cells. Importantly, in vivo models, TW-37 observably increases chemosensitivity of NPC tumors but has not markedly influence on the normal tissues in mice. In conclusion, our results point to TW-37 as a promising ancillary drug for the chemotherapy of NPC.     

Serum CYFRA21-1 as a prognostic marker for patients with undifferentiated nasopharyngeal carcinoma

The purpose of this study was to evaluate the potential of serum CYFRA21-1 and carcinoembryonic antigen (CEA) as prognostic markers in patients with undifferentiated nasopharyngeal carcinoma. Sixty-one patients who received definitive radiotherapy/chemoradiotherapy were analysed retrospectively. We investigated the association of the follow-up results with pretreatment level, post-treatment level and change of serum CYFRA21-1 and CEA, respectively. Patients with low pretreatment CYFRA21-1 had a significantly better overall survival. There were no significant associations among the remaining serum markers, and the survival and recurrence rates on multivariate analysis. The present study shows that pretreatment CYFRA21-1 level is a potential factor for predicting long-term survival.     

Cell-cycle inhibition and apoptosis induced by curcumin and cisplatin or oxaliplatin in human ovarian carcinoma cells

Alteration of appropriate cell‐cycle progression and of closely related apoptotic process is a basic feature of tumour cells, and development of new tumour‐targeted agents focus on apoptosis, either during cell‐cycle arrest or following premature cell‐cycle checkpoint exit. Increasingly, epidemiological and experimental studies suggest that curcumin protects against cancer, not only because of its well‐known antioxidant properties, but also because it modulates intracellular signalling, which is related to cell proliferation and apoptosis. Cisplatin and oxaliplatin are first‐line drugs in treatment of many types of epithelial cancer and their combination with other cytostatics are under investigation to limit their side effects and resistance to them. Objectives: The aim of this study was to evaluate effects of a combined treatment using curcumin with cisplatin or with oxaliplatin, in a human ovarian cancer cell line (2008) and in its cisplatin‐resistant variant (C13). Results: Curcumin per se caused concentration‐dependent (0.1–100 µm ) and time‐persistent (24–72 h) reduction in cell proliferation, as well as altered cell cycle parameters and induced apoptosis, in both cell lines. When carcinoma cells were simultaneously exposed to curcumin and to cisplatin or oxaliplatin (at concentrations lower than IC₅₀) cell viability was reduced more than with single‐drug treatment. Moreover, dose and time related effects of curcumin, when combined with platinum drugs, were linked to consistent reduction in cell cycling and increased apoptosis, in comparison with single‐drug treatment. These effects were significant both in wild type and in cisplatin‐resistant cells, indicating that curcumin was also able to increase sensitivity of resistant ovarian cancer cells to cisplatin. Conclusions: The data suggests that curcumin is an interesting natural compound capable of limiting cell proliferation and possibly increasing clinical impact of platinum drugs, in ovarian cancer patients.     

Identification of label-retaining cells in nasopharyngeal epithelia and nasopharyngeal carcinoma tissues

Adult stem cells can be identified by label-retaining cell (LRC) approach based on their ability to retain nucleoside analog, such as bromodeoxyuridine (BrdU). We hypothesized that mouse nasopharynx contains a small population of epithelial stem/progenitor cells that may be detected by the LRC technique. To identify LRCs in mice nasopharyngeal epithelia, neonatal mice were intraperitoneally injected with BrdU twice daily for 3 consecutive days. After an 8-week chase, long-term BrdU-labeled LRCs (∼2% of cells) were detected in the adult mice nasopharyngeal epithelia by immunostaining with BrdU antibody and some of LRCs (∼12% of cells) were found to be recruited into the S phase of cell cycle with an additional radioactive thymidine-labeling technique, indicating that the stem cells also divide, most likely asymmetrically. To further investigate whether the LRCs existed in human nasopharyngeal carcinoma (NPC) tissues, three NPC cell lines (5-8F, 6-10B and TMNE) were labeled with BrdU in vitro and then individually engrafted into the back of nude mice, which developed tumors. Again, label-retaining stem cells were found in all the three kinds of NPC xenograft tumors (∼0.3% of cells), around 16% of which were also labeled with radioactive thymidine. Thus, this study has demonstrated for the first time the presence of epithelial LRCs in mouse nasopharyngx and human NPC tissues and these stem-like LRCs are not completely quiescent, as they will be recruited into the cell cycle to participate physiological or pathological process at any moment. More importantly, our data showed that NPC also contained stem cells, which are most likely the cause for NPC spread, metastasis and recurrence.     

An experimental model for selective inhibition of proliferating cells by chemotherapeutic agents

Conditionally transformable cells of primate origin in which 'untransformed' and 'transformed' cells derived from the same source grow in culture, has been used as an experimental system for testing selective inhibition of proliferating cells by chemotherapeutic agents. The cytotoxic agents Adriamycin and Mitomycin C fail to recognise "tumour cells" in a heterogenous population and thus differ from the non-toxic and non-carcinogenic agent L-canavanine.     

Demethylation of E-cadherin gene in nasopharyngeal carcinoma could serve as a potential therapeutic strategy

E-cadherin has been proven to be widely down-regulated and tightly associated with tumour invasion and metastasis in multiple human cancer types. Recent research demonstrated that aberrant methylation around gene promoter region attributes to E-cadherin silencing. However, the detailed information about this epigenetic inactivation in nasopharyngeal carcinoma (NPC) is rare. The aim of this study was to probe more into the basic mechanism of E-cadherin methylation in NPC and elucidate the application of demethylating agents to restore E-cadherin expression. To address this question, we initially studied E-cadherin methylation status in NPC primary tumours and cell lines by methylation-specific PCR, and compared it with E-cadherin expression. Methylated E-cadherin was detected in 13 of 20 (65%) NPC clinical specimens and 2 of 2 (100%) NPC cell lines (HNE-1 and CNE-2), which was inversely correlated with E-cadherin expression. The detailed methylation profile at individual CpGs within CpG island of E-cadherin promoter region was confirmed by bisulphite sequencing. E-cadherin gene could be demethylated and reactivated in HNE-1 and CNE-2 cells upon treatment with 5-aza-dC, a DNA demethylating agent. Our findings indicate that frequent aberrant methylation of E-cadherin may play an important role in downregulation of E-cadherin, and demethylation therapy could serve as a promising strategy for NPC patients. Furthermore, a high frequency of E-cadherin methylation (9/20, 45%) in peripheral blood of NPC patients suggests its potential clinical application as an early diagnostic or predictive marker.     

Bioelectrohydrogenesis and inhibition of methanogenic activity in microbial electrolysis cells - A review

Microbial electrolysis cells (MECs) are a promising technology for biological hydrogen production. Compared to abiotic water electrolysis, a much lower electrical voltage (~ 0.2 V) is required for hydrogen production in MECs. It is also an attractive waste treatment technology as a variety of biodegradable substances can be used as the process feedstock. Underpinning this technology is a recently discovered bioelectrochemical pathway known as “bioelectrohydrogenesis”. However, little is known about the mechanism of this pathway, and numerous hurdles are yet to be addressed to maximize hydrogen yield and purity. Here, we review various aspects including reactor configurations, microorganisms, substrates, electrode materials, and inhibitors of methanogenesis in order to improve hydrogen generation in MECs.     

Knockdown of NFBD1/MDC1 enhances chemosensitivity to cisplatin or 5-fluorouracil in nasopharyngeal carcinoma CNE1 cells

Nasopharyngeal carcinoma (NPC) is a rare but highly invasive cancer that is prevalent among people of southern Chinese ancestry in southern China and Southeast Asia. Radiotherapy and cisplatin (CDDP)-based chemotherapy are the main treatment options. Unfortunately, disease response to concurrent chemoradiotherapy varies among patients with NPC, and many cases are resistant to CDDP and radiotherapy. NFBD1 functions in cell cycle checkpoint activation and DNA repair following DNA damage. In this study, we identified the NFBD1 as a tractable molecular target to chemosensitize NPC cells. NFBD1 expression in NPC CNE1 cell lines was depleted using lentivirus-mediated short hairpin RNA, and the elevated sensitivity of these NFBD1-inhibited NPC cells to therapeutic reagent CDDP and 5-fluorouracil (5-FU) was evaluated using MTS assays. Flow cytometry analysis also showed that NFBD1 knockdown led to an obvious induction of apoptosis in CDDP- or 5-FU-treated CNE1 cells. Furthermore, we implicated the involvement of NFBD1 in Rad51 and DNA-PKcs foci formation following CDDP or 5-FU chemotherapy. In conclusion, NFBD1 knockdown improves the chemosensitivity of NPC cells by inhibiting cell growth and promoting apoptosis through the impairment of DNA damage repair, suggesting NFBD1 as a novel therapeutic target for NPC.

     

Transfer factor with anti-EBV activity as an adjuvant therapy for nasopharyngeal carcinoma: A pilot study

Overall survival of nasopharyngeal carcinoma (NPC) at UICC stage IV still remains unsatisfactory even with combination chemotherapy (CT) and radio-therapy (RT). In view of the association of reactivation of Epstein-Barr virus (EBV) with the development and recurrence of NPC, immunotherapy in the form of transfer factor (TF) with specific activity against EBV (TF-B1) was suggested as an adjuvant to a combination of CT and RT in order to improve survival. In the present study, 6 UICC Stage IV patients received TF-B1 and another 6 patients matched for disease stage were given TF prepared from peripheral blood leucocytes (TF-PBL). Results were compared with another 18 patients matched by age, sex, and stage of disease who received standard therapy without TF during the same period (C group). After a median follow up of 47.5 months, the survival for the TF-B1 group was found to be significantly better (P=<0.05) than the PBL and C group. While the 8 patients with distant metastasis (DM), not treated with TF-B1 (6 in the control and 2 in the PBL group), died due to progressive disease (average survival being 14.3 months), both patients with DM in the TF-B1 group had complete remission: one died of tuberculosis after surviving for 3.5 years and another is still alive, disease free, after 4.2 years. Although the series involved a small number of cases, the apparent effect of adjuvant immunotherapy in the form of TF with anti-EBV activity is of considerable interest.