The acquired radioresistance in HeLa cells under conditions mimicking hypoxia was attenuated by a decreased expression of HIF subunit genes induced by RNA interference.

Abstract

The cancer cells residing in the hypoxic layer are resistant to radiation and these are ones responsible for cancer recurrence after radiation therapy. One of the reasons why hypoxic cancer cells acquire radioresistance may be attributable to changes in the gene expression profile by the activation of hypoxia inducible factors (HIFs). However, the details underlying this process remain unknown. In this study, we investigated the effects of knockdown of HIF subunit genes to elucidate how HIF subunit genes may be involved in the radioresistance acquired by HeLa cells following exposure to a hypoxia mimic. Interestingly, HIF-1α and HIF-2α seemed mutually complementary for each other when either of them was suppressed. We thus suppressed the expression of both genes simultaneously. To do this, we developed a short hairpin RNA (shRNA) targeting a high homology region between HIF-1α and HIF-2α. It was shown that the expression of the shRNA effectively suppressed the acquisition of radioresistance following the hypoxia mimic. Moreover, it was confirmed that suppression of both subunits resulted in the downregulation of stem cell markers and the suppression of spheroid formation during the hypoxia mimicking-conditions. This shRNA-mediated knockdown method targeting a common region shared by a family of genes may offer a new candidate cancer treatment.

• Authors: Nobutaka Doi, Ryohei Ogawa, Zheng-Guo Cui, Akihiro Morii, Akihiko Watanabe, Shinji Kanayama, Yuko Yoneda, Takashi Kondo
• Journal: Experimental cell research (Exp Cell Res) Vol. 333 Issue 2 Pg. 249-260 (May 01 2015) ISSN: 1090-2422 [Electronic] United States
• PMID: 25805230 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2015 Elsevier Inc. All rights reserved.

Chemical References

• Basic Helix-Loop-Helix Transcription Factors
• HIF1A protein, human
• Hypoxia-Inducible Factor 1, alpha Subunit
• Protein Subunits
• RNA, Small Interfering
• endothelial PAS domain-containing protein 1
• Cobalt
• cobaltous chloride

Topics

• Base Sequence
• Basic Helix-Loop-Helix Transcription Factors (genetics, metabolism)
• Cell Hypoxia
• Cobalt (pharmacology)
• Gene Expression
• Gene Knockdown Techniques
• HeLa Cells
• Humans
• Hypoxia-Inducible Factor 1, alpha Subunit (genetics, metabolism)
• Protein Subunits (genetics, metabolism)
• RNA Interference
• RNA, Small Interfering (genetics)
• Radiation Tolerance