title: MiR-106b induces cell radioresistance via the PTEN/PI3K/AKT pathways and p21 in colorectal cancer.
abstract: BACKGROUND
  Radioresistance is a challenge in the treatment of patients with colorectal cancer (CRC). Individuals display different therapeutic responses to preoperative radiotherapy, and the need of targeted therapies is urgent. MicroRNAs (miRNAs) are involved in essential biological activities, including chemoresistance and radioresistance. Several research studies have indicated that miRNA played an important role in sensitizing cells to ionizing radiation (IR). MiR-106b, a member of the miR-106b-25 cluster, is frequently dysregulated in many human cancers, including CRC. However, the function of miR-106b in radioresistance is currently poorly understood.
  
  
  METHODS
  A series of in vitro and in vivo studies were performed to investigate the roles of miR-106b on cell radioresistance in CRC.
  
  
  RESULTS
  We found overexpression of miR-106b could induce resistance to IR in vitro and in vivo in SW620 cells. Correspondingly, knocking down miR-106b in SW480 yielded the opposite effect. In addition, overexpression of miR-106b could enhance the tumour-initiating cell capacity without or with IR condition, such as the colony sphere formation capacity and the upregulation of stemness-related genes (CD133, Sox2). We further identified PTEN and p21 as novel direct targets of miR-106b by using target prediction algorithms and a luciferase assay. Overexpression of miR-106b reduced the expression of PTEN and p21 and increased the expression of p-AKT, which is a downstream of PTEN. Restoring the expression of PTEN or p21 in stably miR-106b-overexpressed cells could rescue the effect of miR-106b on cell radioresistance. Together, the acquisition of tumour-initiating cell capacity endowed CRC cells with the potential of resistance to irradiation.
  
  
  CONCLUSIONS
  These observations illustrated that miR-106b could induce cell radioresistance by directly targeting PTEN and p21, this process was accompanied by tumour-initiating cell capacity enhancement, which is universally confirmed to be associated with radioresistance. Our data suggested that miR-106b at least partly induces cell radioresistance in CRC.
authors.affiliation: Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. 147938636@qq.com.|Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. 147938636@qq.com.
authors.forename: Lin
authors.initials: L
authors.lastname: Zheng
authors.affiliation: Department of Oncology, The First Affiliated Hospital of Jinan University, Guangzhou, 510515, Guangdong Province, China. 791369631@qq.com.
authors.forename: Yuqin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. 517955526@qq.com.|Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. 517955526@qq.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. 443913587@qq.com.|Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. 443913587@qq.com.
authors.forename: Min
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. 443768097@qq.com.|Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. 443768097@qq.com.
authors.forename: Yanxia
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. 421418843@qq.com.|Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. 421418843@qq.com.
authors.forename: Li
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. 270850806@qq.com.|Department of Pathology, Sun Yat-Sen University Cancer Center, Guangzhou, 510515, Guangdong Province, China. 270850806@qq.com.
authors.forename: Chao
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. 790664525@qq.com.|Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. 790664525@qq.com.
authors.forename: Min
authors.initials: M
authors.lastname: Hong
authors.affiliation: Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. zhang1987316@126.com.|Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. zhang1987316@126.com.
authors.forename: Shuang
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. nfydlxn@126.com.|Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. nfydlxn@126.com.
authors.forename: Xuenong
authors.initials: X
authors.lastname: Li
mesh_terms: D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism*; D006801:Humans; D008819:Mice, Nude; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D014411:Neoplastic Stem Cells / Q000473:pathology / Q000528:radiation effects; D051059:PTEN Phosphohydrolase / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D011836:Radiation Tolerance / Q000528:radiation effects; D011839:Radiation, Ionizing; D015398:Signal Transduction / Q000528:radiation effects
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; C542541:MIRN106 microRNA, human; D035683:MicroRNAs; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D051059:PTEN Phosphohydrolase