Induction of cell death and inhibition of cell survival are the main principles of cancer therapy. Resistance to chemotherapeutic agents is a major problem in oncology, which limits the effectiveness of anticancer drugs. A variety of factors contribute to drug resistance, including host factors, specific genetic or epigenetic alterations in the cancer cells and so on. Although various mechanisms by which cancer cells become resistant to anticancer drugs in the microenvironment have been well elucidated, how to circumvent this resistance to improve anticancer efficacy remains to be defined. Autophagy, an important homeostatic cellular recycling mechanism, is now emerging as a crucial player in response to metabolic and therapeutic stresses, which attempts to maintain/restore metabolic homeostasis through the catabolic lysis of excessive or unnecessary proteins and injured or aged organelles. Recently, several studies have shown that autophagy constitutes a potential target for cancer therapy and the induction of autophagy in response to therapeutics can be viewed as having a prodeath or a prosurvival role, which contributes to the anticancer efficacy of these drugs as well as drug resistance. Thus, understanding the novel function of autophagy may allow us to develop a promising therapeutic strategy to enhance the effects of chemotherapy and improve clinical outcomes in the treatment of cancer patients.

/pdf/autophagy-and-chemotherapy-resistance-a-promising-2pz6sno24p.pdf

Autophagy and chemotherapy resistance: a promising therapeutic target for cancer treatment

Broad targeting of resistance to apoptosis in cancer.

Multidrug resistance (MDR) occurs frequently after long-term chemotherapy, resulting in refractory cancer and tumor recurrence. Therefore, combatting MDR is an important issue. Autophagy, a self-degradative system, universally arises during the treatment of sensitive and MDR cancer. Autophagy can be a double-edged sword for MDR tumors: it participates in the development of MDR and protects cancer cells from chemotherapeutics but can also kill MDR cancer cells in which apoptosis pathways are inactive. Autophagy induced by anticancer drugs could also activate apoptosis signaling pathways in MDR cells, facilitating MDR reversal. Therefore, research on the regulation of autophagy to combat MDR is expanding and is becoming increasingly important. We summarize advanced studies of autophagy in MDR tumors, including the variable role of autophagy in MDR cancer cells.

/pdf/autophagy-and-multidrug-resistance-in-cancer-2865ylyoc3.pdf

Autophagy and multidrug resistance in cancer

MicroRNAs (miRNAs) are small non-coding RNAs with a length of about 19–25 nt, which can regulate various target genes and are thus involved in the regulation of a variety of biological and pathological processes, including the formation and development of cancer. Drug resistance in cancer chemotherapy is one of the main obstacles to curing this malignant disease. Statistical data indicate that over 90% of the mortality of patients with cancer is related to drug resistance. Drug resistance of cancer chemotherapy can be caused by many mechanisms, such as decreased antitumor drug uptake, modified drug targets, altered cell cycle checkpoints, or increased DNA damage repair, among others. In recent years, many studies have shown that miRNAs are involved in the drug resistance of tumor cells by targeting drug-resistance-related genes or influencing genes related to cell proliferation, cell cycle, and apoptosis. A single miRNA often targets a number of genes, and its regulatory effect is tissue-specific. In this review, we emphasize the miRNAs that are involved in the regulation of drug resistance among different cancers and probe the mechanisms of the deregulated expression of miRNAs. The molecular targets of miRNAs and their underlying signaling pathways are also explored comprehensively. A holistic understanding of the functions of miRNAs in drug resistance will help us develop better strategies to regulate them efficiently and will finally pave the way toward better translation of miRNAs into clinics, developing them into a promising approach in cancer therapy.

/pdf/the-role-and-mechanisms-of-action-of-micrornas-in-cancer-3reepz2l36.pdf

The role and mechanisms of action of microRNAs in cancer drug resistance.

Chemotherapy is a reasonable alternative to cystectomy in patients with invasive and advanced bladder cancer. However, bladder cancer cells often develop drug resistance to these therapies, and ~ 50% of patients with advanced bladder cancer do not respond to chemotherapy. Recent studies have shown that long non-coding RNA (lncRNA) is involved in the development of chemoresistance. Here we investigated the role of the urothelial cancer-associated 1 (UCA1) lncRNA in cisplatin resistance during chemotherapy for bladder cancer. We showed that cisplatin-based chemotherapy results in up-regulation of UCA1 expression in patients with bladder cancer. Similarly, UCA1 levels are increased in cisplatin-resistant bladder cancer cells. Over-expression of UCA1 significantly increases the cell viability during cisplatin treatment, whereas UCA1 knockdown reduces the cell viability during cisplatin treatment. UCA1 inhibition also partially overcomes drug resistance in cisplatin-resistant T24 cells. Furthermore, we showed that UCA1 positively regulates expression of wingless-type MMTV integration site family member 6 (Wnt6) in human bladder cancer cell lines. UCA1 and Wnt6 expression is also positively correlated in vivo. Up-regulation of UCA1 activates Wnt signaling in a Wnt6-dependent manner. We finally demonstrate that UCA1 increases the cisplatin resistance of bladder cancer cells by enhancing the expression of Wnt6, and thus represents a potential target to overcome chemoresistance in bladder cancer.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/febs.12737

Long non-coding RNA UCA1 increases chemoresistance of bladder cancer cells by regulating Wnt signaling.

Cisplatin-induced downregulation of miR-199a-5p increases drug resistance by activating autophagy in HCC cell

Upregulated miR-130a increases drug resistance by regulating RUNX3 and Wnt signaling in cisplatin-treated HCC cell.

OBJECTIVE: Although hepatitis B recurrence after liver transplantation has been reduced to 0%–10% since the application of the combination therapy of hepatitis B immunoglobulin (HBIG) and lamivudine, the viral mutation resistance of lamivudine is still an obstacle to the outcome of liver transplantation. Here we evaluate the role of entecavir in preventing hepatitis B recurrence after liver transplantation.



METHODS:

Patients who received a liver transplantation for hepatitis B virus (HBV)-related end-stage liver disease in our center from March 2006 to December 2008 were enrolled in this study. All patients received entecavir (0.5 mg orally, daily) or lamivudine (100 mg orally, daily) together with a long-term low dosage of HBIG to prevent hepatitis B recurrence after transplantation. Serum viral markers (HBsAg, anti-HBs, HBeAg, anti-HBc and anti-HBe) and HBV-DNA level were determined.



RESULTS:  Thirty patients receiving entecavir and 90 patients receiving lamivudine were matched with the same age and sex in both groups. No reinfection of hepatitis B was detected in the entecavir group. The hepatitis B surface antigen of patients in the entecavir group became negative within one week and no patient had any adverse effect relating to entecavir. There was no difference in the cumulative survival rate between the entecavir group and the lamivudine group (P > 0.05).



CONCLUSION:  This study shows that entecavir combined with low dosages of HBIG is effective and safe in preventing hepatitis B recurrence after liver transplantation, but its long-term effect is still under investigation and a large-sample study will be carried out in the future.

The role of entecavir in preventing hepatitis B recurrence after liver transplantation.

Obesity-related non-alcoholic fatty liver disease (NAFLD) is connected with mitochondrial stress and hepatocyte apoptosis. Parkin-related mitophagy sustains mitochondrial homeostasis and hepatocyte viability. However, the contribution and regulatory mechanisms of Parkin-related mitophagy in NAFLD are incompletely understood. Macrophage stimulating 1 (Mst1) is a novel mitophagy upstream regulator which excerbates heart and cancer apoptosisn via repressing mitophagy activity. The aim of our study is to explore whether Mst1 contributes to NAFLD via disrupting Parkin-related mitophagy. A NAFLD model was generated in wild-type (WT) mice and Mst1 knockout (Mst1-KO) mice using high-fat diet (HFD). Cell experiments were conducted via palmitic acid (PA) treatment in the primary hepatocytes. The results in our study demonstrated that Mst1 was significantly upregulated in HFD-treated livers. Genetic ablation of Mst1 attenuated HFD-mediated hepatic injury and sustained hepatocyte viability. Functional studies illustrated that Mst1 knockdown reversed Parkin-related mitophagy and the latter protected mitochondria and hepatocytes against HFD challenge. Besides, we further figured out that Mst1 modulated Parkin expression via the AMPK pathway; blockade of AMPK repressed Parkin-related mitophagy and recalled hepatocytes mitochondrial apoptosis. Altogether, our data identified that NAFLD was closely associated with the defective Parkin-related mitophagy due to Mst1 upregulation. This finding may pave the road to new therapeutic modalities for the treatment of fatty liver disease.

Mst1 Inhibition Attenuates Non-Alcoholic Fatty Liver Disease via Reversing Parkin-related Mitophagy

We investigated the overall situation of LT for BA in mainland China and analyzed their survival outcomes based on data from CLTR. Between January 1996 and December 2013, 509 liver transplants for BA were performed in mainland China and were included in this study. Patients' median age was 9.6 months (range: 4.8-175.2 months). KP was previously performed in 194 cases (38.1%). Grafts from living donors were used in 380 cases (74.7%). Era I (1996.1-2010.12) and era II (2011.1-2013.12) comprised 151 cases (29.7%) and 358 cases (70.3%), respectively. Twenty-five centers had performed at least one liver transplant for children with BA. Centers from Shanghai (197 cases), Tianjin (143 cases) and Beijing (81 cases) involved 82.7% of the 509 cases. One- and five-yr graft survival rates were 84.7% and 72.6%, respectively. Split grafts, center volume <20, GRWR ≥4.0%, and steroid-free immunosuppression regimen were independent risk factors for graft survival. In conclusion, the dramatic expansion of pediatric liver transplant programs in mainland China has enabled improved survival for those children affected by this devastating disease. However, screening of BA in neonates should be emphasized throughout the country to enhance early referrals for KP.

Yi Luo

Papers

Cisplatin-induced downregulation of miR-199a-5p increases drug resistance by activating autophagy in HCC cell

Upregulated miR-130a increases drug resistance by regulating RUNX3 and Wnt signaling in cisplatin-treated HCC cell.

The role of entecavir in preventing hepatitis B recurrence after liver transplantation.

Mst1 Inhibition Attenuates Non-Alcoholic Fatty Liver Disease via Reversing Parkin-related Mitophagy

Liver transplantation for biliary atresia: A nationwide investigation from 1996 to 2013 in mainland China