MiR-331-3p Links to Drug Resistance of Pancreatic Cancer Cells by Activating WNT/β-Catenin Signal via ST7L

Background: Pancreatic cancer is an aggressive type of cancer with poor prognosis, short survival rate, and high mortality. Drug resistance is a major cause of treatment failure in the disease. MiR-331-3p has been reported to play an important role in several cancers. We previously showed that miR-331-3p is upregulated in pancreatic cancer and promotes pancreatic cancer cell proliferation and epithelial-to-mesenchymal transition–mediated metastasis by targeting ST7L. However, it is uncertain whether miR-331-3p is involved in drug resistance. Methods: We investigated the relationship between miR-331-3p and pancreatic cancer drug resistance. As part of this, microRNA mimics or inhibitors were transfected into pancreatic cancer cells. Quantitative polymerase chain reaction was used to detect miR-331-3p expression, and flow cytometry was used to detect cell apoptosis. The Cell Counting Kit-8 assay was used to measure the IC50 values of gemcitabine in pancreatic cancer cells. The expression of multidrug resistance protein 1, multidrug resistance-related protein 1, breast cancer resistance protein, β-Catenin, c-Myc, Cyclin D1, Bcl-2, and Caspase-3 was evaluated by Western blotting. Results: We confirmed that miR-331-3p is upregulated in gemcitabine-treated pancreatic cancer cells and plasma from chemotherapy patients. We also confirmed that miR-331-3p inhibition decreased drug resistance by regulating cell apoptosis and multidrug resistance protein 1, multidrug resistance-related protein 1, and breast cancer resistance protein expression in pancreatic cancer cells, whereas miR-331-3p overexpression had the opposite effect. We further demonstrated that miR-331-3p effects in drug resistance were partially reversed by ST7L overexpression. In addition, overexpression of miR-331-3p activated Wnt/β-catenin signaling in pancreatic cancer cells, and ST7L overexpression restored activation of Wnt/β-catenin signaling. Conclusions: Taken together, our data demonstrate that miR-331-3p contributes to drug resistance by activating Wnt/β-catenin signaling via ST7L in pancreatic cancer cells. These data provide a theoretical basis for new targeted therapies in the future.

Hepatitis C Virus-Induced FUT8 Causes 5-FU Drug Resistance in Human Hepatoma Huh7.5.1 Cells

Hepatitis C virus (HCV) is a major cause of human chronic liver disease and hepatocellular carcinoma. Our recent studies showed that α1,6-fucosyltransferase (FUT8), a key glycosyltransferase, was the most up-regulated glycosyltransferase after the HCV infection of human hepatocellular carcinoma Huh7.5.1 cells. Here, we further studied the effects and possible mechanism of FUT8 on the proliferation of HCV and chemotherapy-resistance of HCV-infected Huh7.5.1 cells. The effects of FUT8 on the proliferation and drug resistance of HCV-infected Huh7.5.1 cells were analyzed by flow cytometry analysis (FCM), quantitative real-time polymerase chain reaction (qRT-PCR), Western blot analysis and lactate dehydrogenase (LDH) release assay. Results: We found that FUT8 not only promoted Huh7.5.1 proliferation by activating PI3K-AKT-NF-κB signaling, but also stimulated the expression of the drug-resistant proteins P-glycoprotein (P-gp) and multidrug resistance related protein 1 (MRP1) and enhanced the 5-fluorouracil (5-FU) chemo-resistance of Huh7.5.1 cells. Silencing of FUT8 reduced the cell proliferation and increased the 5-FU sensitivity of HCV-infected Huh7.5.1 cells. Inhibition of P-gp and MRP1 increased the 5-FU drug sensitivity in HCV infected Huh7.5.1 cells. HCV-induced FUT8 promotes proliferation and 5-FU resistance of Huh7.5.1 cells. FUT8 may serve as a therapeutic target to reverse chemotherapy resistance in HCV-infected Huh7.5.1 cells.

Progesterone Increases Apoptosis and Inversely Decreases Autophagy in Human Hepatoma HA22T/VGH Cells Treated with Epirubicin

Hepatocellular carcinoma (HCC) is the leading cause of cancer-related deaths worldwide. Epirubicin can induce intracellular reactive oxygen species and is widely used to treat unresectable HCC. Progesterone has been found to inhibit the proliferation of hepatoma cells. This study was designed to test the combined effects of epirubicin and progesterone on human hepatoma cell line, HA22T/VGH. These cells were treated with different concentrations of epirubicin with or without the coaddition of 30 μM progesterone and then analyzed for apoptosis, autophagy, and expressions of apoptotic-related proteins and multidrug-resistant gene. Epirubicin treatment dose-dependently inhibited the growth of HA22T/VGH cells. Addition of 30 μM progesterone, which was inactive alone, augmented the effect of epirubicin on the inhibition of growth of HA22T/VGH cells. Cotreatment with progesterone enhanced epirubicin-induced apoptosis, as evidenced by greater increase in caspase-3 activity and in the ratio of the apoptosis-regulating protein, Bax/Bcl-XL. The combination also caused a decrease in autophagy and in the expression of multidrug resistance-related protein 1 mRNA compared to epirubicin alone. This study shows the epirubicin/progesterone combination was more effective in increasing apoptosis and inversely decreasing autophagy on HA22T/VGH cells treated with epirubicin alone, suggesting that this combination can potentially be used to treat HCC.