title: 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: Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan; New Products Research & Development, Gene Engineering Division, NIPPON GENE Co., Ltd., Japan.
authors: Nobutaka
authors: N
authors: Doi
authors: Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan. Electronic address: ogawa@med.u-toyama.ac.jp.
authors: Ryohei
authors: R
authors: Ogawa
authors: Department of Public Health, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Japan.
authors: Zheng-Guo
authors: ZG
authors: Cui
authors: Department of Urology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Japan.
authors: Akihiro
authors: A
authors: Morii
authors: Department of Urology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Japan.
authors: Akihiko
authors: A
authors: Watanabe
authors: New Products Research & Development, Gene Engineering Division, NIPPON GENE Co., Ltd., Japan.
authors: Shinji
authors: S
authors: Kanayama
authors: New Products Research & Development, Gene Engineering Division, NIPPON GENE Co., Ltd., Japan.
authors: Yuko
authors: Y
authors: Yoneda
authors: Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan.
authors: Takashi
authors: T
authors: Kondo
mesh_terms: D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D015687:Cell Hypoxia; D003035:Cobalt / Q000494:pharmacology; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D011836:Radiation Tolerance; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D003035:Cobalt; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D021122:Protein Subunits; D034741:RNA, Small Interfering; D000099162:Endothelial PAS Domain-Containing Protein 1; C497442:HIF1A protein, human; C018021:cobaltous chloride
keywords: Cancer stem cell; Cobalt chloride; HIF; Hypoxia; Radiation; shRNA