Comprehensive molecular exploration identified promoter DNA methylation of the CRBP1 gene as a determinant of radiation sensitivity in rectal cancer

Abstract

Background:Neoadjuvant chemoradiotherapy (NCRT) for advanced rectal cancer (RC) is a well-evidenced therapy; however, some RC patients have no therapeutic response. Patient selection for NCRT so that non-responsive patients are excluded has been subjective. To date, no molecular markers indicating radiation sensitivity have been reported.Methods:We irradiated six colorectal cancer (CRC) cell lines and identified HCT116 cells as radiation-sensitive and HCT15 and DLD-1 cells as radiation resistant. Using a microarray, we selected candidate radiation sensitivity marker genes by choosing genes whose expression was consistent with a radiation-resistant or sensitive cell phenotype.Results:Among candidate genes, cellular retinol binding protein 1 (CRBP1) was of particular interest because it was not only induced in HCT116 cells by tentative 10 Gy radiation treatments, but also its expression was increased in HCT116-derived radiation-resistant cells vs parental cells. Forced expression of CRBP1 decreased the viability of both HCT15 and DLD-1 cells in response to radiation therapy. We also confirmed that CRBP1 was epigenetically silenced by hypermethylation of its promoter DNA, and that the quantitative methylation value of CRBP1 significantly correlated with histological response in RC patients with NCRT (P=0.031).Conclusions:Our study identified CRBP1 as a radiation-sensitive predictor in RC.

Comprehensive Analysis of DNA Methylation and Prediction of Response to NeoadjuvantTherapy in Locally Advanced Rectal Cancer

“…Most of the studies describing DNA methylation in LARC evaluated a small panel of genes as biomarkers of nCRT response. Hypermethylation of ATM (ATM serine/threonine kinase), CRBP1 (RBP1 retinol binding protein 1), MGMT, TFAP2E (transcription factor AP-2 epsilon), and TIMP3 (metallopeptidase inhibitor 3) genes was associated with response to radiotherapy and/or 5-FU (5-fluorouracil) based chemotherapy in ReCa [17,20,31,42,43]. In our study, five probes hypermethylated in TFAP2E and one hypomethylated in TIMP3 were found in both groups (pCR and pIR) compared to NT.…”

Predictive immunohistochemical features for tumour response to chemoradiotherapy in rectal cancer

“…This variation could be ascribed to the use of different methodologies. Some studies also examined genetic/epigenetic changes or protein expression levels, although research is still at an early stage. Nevertheless, large‐scale validation studies of predictive markers are necessary before incorporating such methodologies into future clinical practice.…”

DNA hypermethylation as a predictor of extramural vascular invasion (EMVI) in rectal cancer

“…51 With regards methylation, Yokoi recently reported that DNA methylation may play an important role in affecting response to radiotherapy in an in vitro colorectal cell line model. 52 This process was dependent on methylation controlled expression of cellular retinol binding protein 1; cellular response to radiotherapy being strongly related to expression. In our study, CIMP-intermediate was associated with strong trend towards requirement for adjuvant chemotherapy (p D 0.055), although it did not reach significance and was not an independent risk factor for DFS or OS.…”