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Gene expression profiling study by RNA-seq to identify gene signature resposed to chemo-radiotherapy in colorectal cancers.

ABSTRACT: The objective of this study is to assess gene expression changes and identify gene sets associated with chemo-radiotherapy (CRT) in colorectal cancer (CRC) patients. We performed RNA-seq based transcriptome profiling using primary tumor samples obtained from 22 CRC patients. By a number of statistical tests, a total of 575 genes were statistically significant, indicating a gene set profoundly responded to chemo-radiotherapy in CRC. To select the genes showing strong gene expression intensities and critically validate the differences between treatment-responded and non-responded patients, we applied more rigorous cut-off for gene selection, revealing a total of 8 final gene candidates. These genes were applied to the downstream experimental assays.

ORGANISM(S): Homo sapiens

PROVIDER: GSE80606 | GEO | 2020/12/25

REPOSITORIES: GEO

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Project description:Background: MicroRNAs (miRNAs) are small, non-coding, RNA molecules which regulate numerous cellular processes. Specific miRNA may be abnormally down-regulated or up-regulated in colorectal cancer and have been found associated with prognosis or response to treatments. However, no study has ever addressed their predictive role in rectal cancer. Therefore, we used microarray technology and RT-PCR to profile miRNA expression patterns in patients (pts) with rectal cancer, with the aim to identify a specific M-bM-^@M-^\signatureM-bM-^@M-^] associated with pathological complete response after neoadjuvant chemo-radiotherapy. Methods: 38 pts with locally advanced rectal cancer (cT3-4/N+) were treated with capecitabine-oxaliplatin and pelvic conformal radiotherapy (45 cGy) followed by surgery (after 6-8 weeks). Pathologic response was scored according to the tumor regression grade (TRG) scale. MiRNA expression profile was analysed by microarray on fresh frozen biopsies obtained before treatment start and confirmed by RT-PCR. The correlation between miRNA expression profile and the TRG coded as TRG1 (pathologic Complete Response-pCR) versus TRG >1 (no pCR) was assessed by statistical analysis methods specifically designed for this study. Findings: 14 miRNAs were selected by arrays analysis as differentially expressed in TRG1 pts and 13 were confirmed by RT-PCR. In particular, 11 miRNAs (miR-1183, miR-483-5p, miR-622, miR-125a-3p, miR-1224-5p, miR-188-5p, miR-1471, miR-671-5p, miR-1909*, miR-630 and miR-765) were significantly up-regulated in TRG1 pts, while 2 miRNAs were under -expressed (miR-1274b and miR-720). miR-622 and miR-630 showed 100% sensitivity and specificity in selecting TRG1 cases and were significantly correlated with EGFR (M-OM-^G2=11M-bM-^@M-"793; p= 0M-bM-^@M-"001) and TS expression (M-OM-^G2=10M-bM-^@M-"589; p= 0M-bM-^@M-"001). Interpretation: A set of 13 miRNAs is strongly associated with pathologic complete response and may represent a specific marker of response to chemo-radiotherapy in locally advanced rectal cancer. Experiments were performed on purified RNA from preoperatory biopsies of 38 patients with histological diagnosis of rectal adenocarcinoma invading through the intestinal wall and/or with pelvic lymph node involvement as evaluated by endorectal ultrasonography (uT3-T4 and/or uN+). Patients were treated with neoadjuvant chemo-radiotherapy (capecitabine + oxaliplatin in combination with 45 Gy of pelvic conformal radiotherapy). Patients have been divided in the following two groups: group A those who had obtained a pathologic complete response M-bM-^@M-^S TRG 1, including the patient without detectable disease who refused surgery, group B any pathologic response other than complete.

Project description:Background: While much progress has been accomplished in the understanding of radiation-induced immune effects in tumors, little is known regarding the mechanisms involved at the tumor draining lymph node (TDLN) level following tumor irradiation. The objective of this retrospective study was to assess the immune and biological changes arising in TDLN upon concurrent chemoradiotherapy of primary non-small cell lung cancer (NSCLC) tumors. Methods: Patients with proved localized (cN0M0) NSCLC, treated by radical surgery plus lymph node dissection with (CRT+) or without (CRT-) neoadjuvant chemoradiotherapy, whereby radiotherapy was targeted on the primary tumor with no significant incidental irradiation of the TDLN station (stations XI or X), were identified. Bulk RNA-Seq of TDLNs was performed and data were analyzed based on differential gene expression (DEG) and gene sets enrichment. Results: Sixteen patients were included and 25 TDLNs were analyzed: 6 patients in the CRT+ group (12 samples) and 10 patients in the CRT- group (13 samples). Overall, 1001 genes were differentially expressed between the two groups (CRT+ and CRT-). Analysis with g-profiler revealed that gene sets associated with antitumor immune response, inflammatory response, hypoxia, angiogenesis, epithelial mesenchymal transition and extra-cellular matrix remodeling were enriched in the CRT+ group, whereas only gene sets associated with B cells and B-cell receptor signaling were enriched in the CRT- group. Unsupervised dimensionality reduction identified two clusters of TDLNs from CRT+ patients, of which one cluster (cluster 1) exhibited higher expression of pathways identified as enriched in the overall CRT+ group in comparison to the CRT- group. In CRT+ cluster 1, 3 out of 3 patients had pathological complete response (pCR) or major complete response (MPR) to neoadjuvant CRT, whereas only 1 out of 3 patients in the other CRT+ cluster (cluster 2) experienced MPR and none exhibited pCR. Finally, pathway comparison to published data from pre-metastatic TDLNs uncovered similarities with CRT+ cluster 1. Conclusion: Neoadjuvant concurrent chemoradiotherapy of the primary tumor in N0 NSCLC patients is associated with distinct microenvironment and immunological patterns in TDLNs as compared to TDLNs from patients with non-irradiated tumors. Our data are in line with studies showing superiority of lymph node sparing irradiation of the primary tumor in the induction of systemic antitumor immunity.

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Gene expression profiling study by RNA-seq to identify gene signature resposed to chemo-radiotherapy in colorectal cancers.

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