Enhancement of Drug Sensitivity by Knockdown of HIF-1α in Gastric Carcinoma Cells

Abstract

In this study, the effects of hypoxia-inducible factor-1α (HIF-1α) on gastric carcinoma (GC) drug resistance through apoptosis-related genes are investigated. First, HIF-1α-specific siRNA was synthetized and transfected into drug-resistant GC cell line OCUM-2MD3/L-OHP. Then MTT assay was applied to test the inhibition rate of GC cells by 5-fluorouracil (5-FU) and oxaliplatin (L-OHP). After that, flow cytometry (FCM) was applied to measure apoptosis rate. qPCR and Western blot assay were employed to detect HIF-1α and apoptosis-related genes. Results showed that HIF-1α in OCUM-2MD3/L-OHP cells was higher than that in OCUM-2MD3 and gastric epithelial cells. After HIF-1α-siRNA transfection, inhibition rates of 5-FU and L-OHP to tumor cells increased significantly. FCM results showed that apoptosis rate of OCUM-2MD3/L-OHP cells increased significantly. After HIF-1α-siRNA transfection, survivin and Bcl-2 decreased, whereas Bax, caspase 3, and caspase 8 increased significantly. Results from this study seem to confirm that HIF-1α getting involved in GC drug resistance is possibly due to its regulation of some apoptosis-related genes. HIF-1α may be a potential target to reverse drug resistance of GC.

The effect of HIF-1α and PKM1 expression on acquisition of chemoresistance

“… 31 Our findings demonstrated that the expression of Bcl-xL was markedly increased in rMKN45-PTX, which is in line with previous studies. 32 – 34 The involvement of HIF-1α in chemoresistance acquisition is possibly due to its role in the regulation of some apoptosis-related genes.…”

The Drug-Resistance Mechanisms of Five Platinum-Based Antitumor Agents

“…Whereas under hypoxic conditions, impaired hydroxylation process stabilizes the HIF1a protein, furthermore HIF1a will translocate into nuclear and dimerize with HIF1b to transactivate the target genes which relate with glucose metabolism, angiogenesis, cell proliferation, invasion and metastasis (reviewed in Pawlus and Hu, 2013;Soni and Padwad, 2017). HIF1a has a strong association with apoptosis; it regulates apoptosis-related genes (i.e., Bcl-2, Bax, caspase 3, caspase 8) (Hernandez-Luna et al, 2013;Zhao et al, 2016), and survival signaling pathways such as NF-kB (Rohwer et al, 2010). Zheng et al recently found that HIF-1a could activate the PI3K/ AKT by up-regulating Mxd1 expression to suppress the PTEN expression (Zheng et al, 2017a).…”

The role of HIF-1α in chemo-/radioresistant tumors

“… 59 Zhao et al recently, in a gastric cancer study, showed that after knockdown of HIF-1α in gastric cancer cells, both the decreased expression of survivin and the increased expression of proapoptotic proteins (notably, Bax and caspase 3/8) were found. Furthermore, Zhao et al 60 proposed that chemo-/radiotherapy-induced apoptosis of tumor cells was significantly increased ( Table 1 ). In addition, in human colon cancer cells, Pei et al reported that HIF-1α decreased proapoptotic signaling by inhibiting the extrinsic cell death pathway, which allows cells to tolerate higher levels of chemotherapeutic injury before activating cellular death pathways.…”