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

Mitsuyoshi Okazaki; Sachio Fushida; Tomoya Tsukada; Jun Kinoshita; Katsunobu Oyama; Tomoharu Miyashita; Itasu Ninomiya; Shinichi Harada; Tetsuo Ohta

doi:10.2147/CMAR.S166136

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

Cancer Manag Res. 2018 Jul 4:10:1865-1874. doi: 10.2147/CMAR.S166136. eCollection 2018.

Authors

Mitsuyoshi Okazaki¹, Sachio Fushida¹, Tomoya Tsukada¹, Jun Kinoshita¹, Katsunobu Oyama¹, Tomoharu Miyashita¹, Itasu Ninomiya¹, Shinichi Harada², Tetsuo Ohta¹

Affiliations

¹ Department of Gastroenterological Surgery, Division of Cancer Medicine, Graduate School of Medical Science, Kanazawa University, Ishikawa, Japan, fushida@staff.kanazawa-u.ac.jp.
² Center for Biomedical Research and Education, School of Medicine, Kanazawa University, Ishikawa, Japan.

Abstract

Background: In patients with gastric cancer, one of the greatest obstacles to effective chemotherapy is the development of chemoresistance. It has been previously reported that hypoxia-inducible factor-1 alpha (HIF-1α) is associated with acquisition of chemoresistance, and more recent studies have also noted an association of pyruvate kinase muscle 1 (PKM1) and chemoresistance. The purpose of this study was to identify the effect of HIF-1α and PKM1 expression on the development of acquired chemoresistance using a paclitaxel (PTX)-resistant gastric cancer cell line.

Materials and methods: A cancer cell line resistant to PTX was established from MKN45 cells by stepwise exposure to drug (rMKN45-PTX). The expressions of HIF-1α, apoptosis, vascular endothelial growth factor (VEGF), multidrug transporters and glycolytic enzyme were examined by Western blotting, enzyme-linked immunosorbent assay and immunohistochemistry. We also assessed the tumor proliferation by subcutaneous tumor and peritoneal dissemination of mouse xenograft model.

Results: The resistance index was 6.1 by determining as the ratio of the 50% growth inhibition (IC₅₀) of rMKN45-PTX/IC₅₀ of MKN45. Expression of nuclear factor kappa B and HIF-1α was increased in rMKN45-PTX cells compared with the parent cells. Expression of Bax and caspase-3 was significantly downregulated, whereas expression of Bcl-xL, P-glycoprotein, multidrug resistance-associated protein and VEGF was increased in rMKN45-PTX. The expression level of PKM1 was upregulated in rMKN45-PTX, leading to an increase in the PKM1/PKM2 ratio. Using xenograft models, we demonstrated that mouse subcutaneous tumors derived from rMKN45-PTX were significantly larger than those derived from MKN45 cells.

Conclusion: Under the stress of chemotherapeutic agent exposure, high expression of HIF-1α affects various downstream genes. Although the underlying mechanism is unknown, our data suggest that PKM1 is also a molecular target for gastric cancer treatment.

Keywords: HIF-1α; PKM1; chemoresistance; gastric cancer.