title: Epigenetic regulation of KLHL34 predictive of pathologic response to preoperative chemoradiation therapy in rectal cancer patients.
abstract: OBJECTIVE
  Prediction of individual responsiveness to preoperative chemoradiation therapy (CRT) is urgently needed in patients with poorly responsive locally advanced rectal cancer (LARC).
  
  
  METHODS
  Candidate methylation genes associated with radiosensitivity were identified using a 3-step process. In the first step, genome-wide screening of methylation genes was performed in correlation with histopathologic tumor regression grade in 45 patients with LARC. In the second step, the methylation status of selected sites was analyzed by pyrosequencing in 67 LARC patients, including 24 patients analyzed in the first step. Finally, colorectal cancer cell clones with stable KLHL34 knockdown were generated and tested for cellular sensitivity to radiation.
  
  
  RESULTS
  Genome-wide screening identified 7 hypermethylated CpG sites (DZIP1 cg24107021, DZIP1 cg26886381, ZEB1 cg04430381, DKK3 cg041006961, STL cg00991794, KLHL34 cg01828474, and ARHGAP6 cg07828380) associated with preoperative CRT responses. Radiosensitivity in patients with hypermethylated KLHL34 cg14232291 was confirmed by pyrosequencing in additional cohorts. Knockdown of KLHL34 significantly reduced colony formation (KLHL34 sh#1: 20.1%, P=.0001 and KLHL34 sh#2: 15.8%, P=.0002), increased the cytotoxicity (KLHL34 sh#1: 14.8%, P=.019 and KLHL34 sh#2: 17.9%, P=.007) in LoVo cells, and increased radiation-induced caspase-3 activity and the sub-G1 population of cells.
  
  
  CONCLUSIONS
  The methylation status of KLHL34 cg14232291 may be a predictive candidate of sensitivity to preoperative CRT, although further validation is needed in large cohorts using various cell types.
authors: Department of Surgery, University of Ulsan College of Medicine, Seoul, Korea; Institute of Innovative Cancer Research and Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea.
authors: Ye J
authors: YJ
authors: Ha
authors: Department of Surgery, University of Ulsan College of Medicine, Seoul, Korea.
authors: Chan W
authors: CW
authors: Kim
authors: Department of Surgery, University of Ulsan College of Medicine, Seoul, Korea; Institute of Innovative Cancer Research and Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea.
authors: Seon A
authors: SA
authors: Roh
authors: Institute of Innovative Cancer Research and Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea; Graduate School of East-West Medical Science, Kyung Hee University, Gyeonggi-do, Korea.
authors: Dong H
authors: DH
authors: Cho
authors: Medical Genomics Research Center, Korea Research Institute of Bioscience & Biotechnology, Daejeon, Korea.
authors: Jong L
authors: JL
authors: Park
authors: Medical Genomics Research Center, Korea Research Institute of Bioscience & Biotechnology, Daejeon, Korea.
authors: Seon Y
authors: SY
authors: Kim
authors: Department of Radiation Oncology, University of Ulsan College of Medicine, Seoul, Korea.
authors: Jong H
authors: JH
authors: Kim
authors: Department of Radiation Oncology, University of Ulsan College of Medicine, Seoul, Korea; Institute of Innovative Cancer Research and Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea.
authors: Eun K
authors: EK
authors: Choi
authors: Medical Genomics Research Center, Korea Research Institute of Bioscience & Biotechnology, Daejeon, Korea; Institute of Innovative Cancer Research and Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea. Electronic address: yongsung@kribb.re.kr.
authors: Yong S
authors: YS
authors: Kim
authors: Department of Surgery, University of Ulsan College of Medicine, Seoul, Korea; Institute of Innovative Cancer Research and Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea. Electronic address: jckim@amc.seoul.kr.
authors: Jin C
authors: JC
authors: Kim
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D018925:Chemokines; D059248:Chemoradiotherapy; D018899:CpG Islands / Q000235:genetics*; D019175:DNA Methylation; D044127:Epigenesis, Genetic / Q000502:physiology*; D005260:Female; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D005819:Genetic Markers; D055106:Genome-Wide Association Study; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D011300:Preoperative Care; D011836:Radiation Tolerance / Q000235:genetics; D012004:Rectal Neoplasms / Q000235:genetics* / Q000473:pathology / Q000628:therapy*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D016896:Treatment Outcome; D000071799:Zinc Finger E-box-Binding Homeobox 1
chemical_list: C109971:ARHGAP6 protein, human; D048868:Adaptor Proteins, Signal Transducing; D018925:Chemokines; C498624:DKK3 protein, human; C492524:DZIP1 protein, human; D020690:GTPase-Activating Proteins; D005819:Genetic Markers; D018398:Homeodomain Proteins; D036341:Intercellular Signaling Peptides and Proteins; D014157:Transcription Factors; C486307:ZEB1 protein, human; D000071799:Zinc Finger E-box-Binding Homeobox 1