Dataset Information

Molecular Characterization of Colorectal Signet-Ring Cell Carcinoma Using Whole-Exome and RNA Sequencing.

ABSTRACT:

Background

Signet-ring cell carcinoma (SRCC) is a very rare subtype of colorectal adenocarcinoma (COAD) with a poor clinical prognosis. Although understanding key mechanisms of tumor progression in SRCCs is critical for precise treatment, a comprehensive view of genomic alterations is lacking.

Materials and methods

We performed whole-exome sequencing of tumors and matched normal blood as well as RNA sequencing of tumors and matched normal colonic tissues from five patients with SRCC.

Results

We identified major somatic alterations and characterized transcriptional changes at the gene and pathway level. Based on high-throughput sequencing, the pattern of mutations and copy number variations was overall similar to that of COAD. Transcriptome analysis revealed that major transcription factors, such as SRF, HNF4A, ZEB1, and RUNX1, with potential regulatory roles in key pathways, including focal adhesion, the PI3K-Akt signaling pathway, and the MAPK signaling pathway, may play a role in the tumorigenesis of SRCC. Furthermore, significantly upregulated genes in SRCCs were enriched for epithelial-mesenchymal transition genes, and accumulation of mucin in intracytoplasm was associated with the overexpression of MUC2.

Conclusion

The results indicate that the molecular basis of colorectal SRCC exhibits key differences from that of consensus COAD. Our findings clarify important genetic features of particular abnormalities in SRCCs.

SUBMITTER: Nam JY

PROVIDER: S-EPMC6051939 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundWe performed a retrospective study to assess the clinicopathological characters, molecular alterations and multigene mutation profiles in colorectal cancer patients with signet-ring cell component.MethodsBetween November 2008 and January 2015, 61 consecutive primary colorectal carcinomas with signet-ring cell component were available for pathological confirmation. RAS/BRAF status was performed by direct sequencing. 14 genes associated with hereditary cancer syndromes were analyzed by targeted gene sequencing.ResultsA slight male predominance was detected in these patients (59.0%). Colorectal carcinomas with signet-ring cell component were well distributed along the large intestine. A frequently higher TNM stage at the time of diagnosis was observed, compared with the conventional adenocarcinoma. Family history of malignant tumor was remarkable with 49.2% in 61 cases. The median OS time of stage IV patients in our study was 14 months. RAS mutations were detected in 22.2% (12/54) cases with KRAS mutations in 16.7% (9/54) cases and Nras mutations in 5.4%(3/54) cases. BRAF V600E mutation was detected in 3.7% (2/54) cases. As an exploration, we analyzed 14 genes by targeted gene sequencing. These genes were selected based on their biological role in association with hereditary cancer syndromes. 79.6% cases carried at least one pathogenic mutation. Finally, the patients were classified by the percentage of signet-ring cell. 39 (63.9%) cases were composed of ≥50% signet-ring cells; 22 (36.1%) cases were composed of <50% signet-ring cells. We compared clinical parameters, molecular and genetic alterations between the two groups and found no significant differences.ConclusionsColorectal adenocarcinoma with signet-ring cell component is characterized by advanced stage at diagnosis with remarkable family history of malignant tumor. It is likely a negative prognostic factor and tends to affect male patients with low rates of RAS /BRAF mutation. Colorectal patients with any component of signet-ring cells, regardless of the extent, shared similar clinicopathological characteristics, molecular alterations and genetic profiles.