Overexpression of EPB41L3 Enhances the Apoptosis-Promoting Effect of Cis-Dichlorodiammine-Platinum in Esophageal Squamous Cell Carcinoma

Abstract

Objective: Cis-dichlorodiammine-platinum (CDDP) is an important drug in chemotherapy regimen for esophageal squamous cell carcinoma (ESCC). Unfortunately, CDDP, even at moderate doses, has toxic effects on normal cells and adverse effects in patients. Erythrocyte membrane protein band 4.1-like 3 (EPB41L3) acts as a cancer inhibitor in many cancers by promoting apoptosis and inhibiting tumor cell proliferation. Therefore, we investigated the potential synergistic anti-ESCC effect of EPB41L3 and CDDP for improving effectiveness of CDDP and lowering CDDP dosage. Methods: EPB41L3 expression in ESCC tissues and cells was examined using Real-Time Quantitative Reverse Transcription PCR (qRT-PCR). ESCC cell models were treated with EPB41L3 transfection alone (EPB41L3 group), CDDP (2 μM) treatment alone (CDDP group), or combined EPB41L3 transfection and CDDP treatment (CDDP+EPB41L3 group), respectively. Cell Counting Kit-8 (CCK-8) was used to examine the cell proliferation in each group. The cell viability of each group was evaluated through cell colony assay. Cell apoptosis and cycles were evaluated using flow cytometry. Western blotting was performed to examine the levels of apoptosis-related proteins and cell cycle-related proteins in each group. Results: The expression level of EPB41L3 in ESCC tissues and cells was reduced, compared with control group. ESCC cell proliferation and cell viability in the CDDP+EPB41L3 group were lower as compared to those in EPB41L3 and CDDP groups. The CDDP+EPB41L3 group showed higher levels of apoptosis, Bax proteins and cleaved-Caspase3, whereas lower level of Bcl-2 protein was shown in ESCC cells, as compared to the other two groups respectively. The G2/M phase ratio and p21 protein levels of ESCC cells treated with both EPB41L3 and CDDP were increased as compared to those in the other two groups. In terms of G0/G1 phase ratio and cyclin-dependent kinases (CDK)1, CDK2 and Cyclin B protein levels, the CDDP+EPB41L3 group exhibited much lower levels than those in the other two groups. Conclusions: Overexpression of EPB41L3 increased the apoptosis-promoting effect of CDDP and its blocking effect on ESCC cells in the G2/M phase, by which the effect of CDDP on inhibiting ESCC cell proliferation and cell viability is improved. This study offers new perspectives on the clinical application of CDDP in the management of ESCC when combined with adjuvant therapy.