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Gene and microRNA expression predictive of tumour response in patients treated with pCRT for LARC

ABSTRACT: The goal of this work is to find robust predictors of tumor response to preoperative chemoradiotherapy in LARC patients. Preoperative chemoradiotherapy (pCRT) followed by surgery is the standard treatment for locally advanced rectal cancer (LARC). However, tumour response to pCRT is not uniform and there are no effective predictive methods. This study investigated whether specific gene and miRNA expression is associated with response to pCRT. Tissue biopsies were obtained from patients before pCRT and resection. Gene and miRNA expression was analyzed using one-color microarrays technique comparing signatures between responders (R) and not responders(NR), as measured by tumour regression grade (TRG). Two groups composed by 38 “exploration cohort” and 21 “validation cohort” LARC patients respectively were considered, for a total of 32 NR and 27 R patients. In the first cohort, SAM Two Class identified 256 genes and 29 miRNAs differentially expressed between NR and R. The anti-correlation analysis showed that the same 8 miRNA interacted with different networks of transcripts. The miR-630 appeared only with NR patients and was anti-correlated with a single transcript: RAB5B. After PAM, resulted as strong predictors of tumour responsen the following 8 transcripts: TMEM188, ITGA2, NRG, TRAM1, BCL2L13, MYO1B, KLF7 and GTSE1. Using this gene set, an unsupervised cluster analysis applied to the second cohort assigned the patients to the NR or R group with 85.7% accuracy with a sensitivity of 90% and a specificity of 82%. All the three parametres reached 100% when the two cohorts were considered together.

ORGANISM(S): Homo sapiens

PROVIDER: GSE68204 | GEO | 2016/04/22

SECONDARY ACCESSION(S): PRJNA282020

REPOSITORIES: GEO

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Project description:Using Human WG CodeLink microarrays, we established the expression profiling of 26 LARC without metastasis to gain insight into the molecular signatures associated with response to treatment after CRT. The study initially included a total of 35 consecutive patients with locally advanced rectal cancer (LARC) treated at Virgen de las Nieves Hospital from 2008 until 2010. Written informed consent was obtained from all the patients, and the study protocol was approved by the local Clinical Research (Ethics) Committee. They were distributed in two subgroups following a histological classification of response to treatment. Pretherapeutic staging was performed, including complete medical history and physical evaluation, digital rectal examination, endorectal ultrasound, rigid rectoscopy, colonoscopy, PET/TC and chest x-ray. Tumor samples were prospectively obtained during the rectoscopy. All patients subsequently received a total dose of 50.4Gy of radiatio (28 fractions of 1.8Gy) associated with capecitabine or capecitabine and oxaliplatine. Standardized surgery was performed, including total mesorectal excision, after an interval of 8 weeks after chemoradiotherapy. Tumor response was assessed in surgical specimen by semi-quantitative pathological examination (regression grade) including UICC stage. Histopathological tumor regression was graded based on the semiquantitative 5 point tumor regression grading (TRG) system: TRG1 or a TRG2 scores were considered Responders, whereas TRG3, TRG4, and TRG5 scores were classified as Non-Responders. In addition, the tumor regression or radiotherapy effects were assessed by positron emission tomography (18F-FDG PET). Tumor samples of LARC were collected from 35 patients. Nine patients were finally excluded due to the poor quality of the RNA or contradictory results of MandardM-BM-4s criteria and histopathological downstaging, resulting a total of 26 patients. Complete clinical data regarding, age, sex, stage of disease, response to therapy, and overall survival from 26 patients (10 responders and 16 non-responders) was provided in the sample characteristics field. CRT: Chemoradiation; Cap: Capecitabine; Capox: Capecitabine and Oxaliplatine; cTN: clinical stage; Surg: surgical technique; LAR: Low anterior resection; APR: Abdmino-perineal resection; HART: Hartmann, TRG: Tumor Regression Grade; Downst: Downstaging; Downs: downsizing, Resp: response, CPR: complete pathologic response

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Gene and microRNA expression predictive of tumour response in patients treated with pCRT for LARC

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