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Gender-related prognostic value and genomic pattern of intra-tumor heterogeneity in colorectal cancer.

ABSTRACT: Intra-tumor heterogeneity (ITH) is crucial in tumorigenesis and resistance to target therapy. Here, we used mutant-allele tumor heterogeneity (MATH) to measure ITH based on next-generation sequencing data and high MATH was proven as an independent risk prognostic factor in male CRC patients in both a training set of 284 colorectal cancer (CRC) patients with from The Cancer Genome Atlas (TCGA) and a validating set of 187 CRC patients from International Cancer Genome Consortium (ICGC). Further, the genomic pattern according to MATH demonstrated that mutation rates of TP53, IRF5 and KRAS were independently associated with MATH, and the latter two were only significant in male patients. As MATH increased, the fraction of somatic copy number alteration (SCNA) elevated. Moreover, more SCNA events was independently associated with MATH in male than in female. WNT pathway, TGF-? pathway and DNA repair deficiency was enriched in high MATH group and the latter two showed up only in male patients. In summary, we reveal the gender-related prognostic value of MATH and relevant genomic pattern in CRC. Potential mechanisms are provided and it remains to be proven whether they are drivers of subclone formation and ITH. Taking MATH into consideration in clinical trial might contribute to better therapeutic strategies in CRC with researches added on in the future.

SUBMITTER: Zhang J

PROVIDER: S-EPMC5862243 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Gender-related prognostic value and genomic pattern of intra-tumor heterogeneity in colorectal cancer.

Zhang Jieyun J Yan Shican S Liu Xiyu X Gan Lu L Wu Zhenhua Z Gong Yiwei Y Huang Mingzhu M Zhang Xiaowei X Guo Weijian W

Carcinogenesis 20170801 8

Intra-tumor heterogeneity (ITH) is crucial in tumorigenesis and resistance to target therapy. Here, we used mutant-allele tumor heterogeneity (MATH) to measure ITH based on next-generation sequencing data and high MATH was proven as an independent risk prognostic factor in male CRC patients in both a training set of 284 colorectal cancer (CRC) patients with from The Cancer Genome Atlas (TCGA) and a validating set of 187 CRC patients from International Cancer Genome Consortium (ICGC). Further, th ...[more]

PMID: 28531253

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Project description:BackgroundIntra-tumor heterogeneity (ITH) of colorectal cancer (CRC) complicates molecular tumor classification, such as transcriptional subtyping. Differences in cellular states, biopsy cell composition, and tumor microenvironment may all lead to ITH. Here we analyze ITH at the transcriptomic and proteomic levels to ascertain whether subtype discordance between multiregional biopsies reflects relevant biological ITH or lack of classifier robustness. Further, we study the impact of tumor location on ITH.MethodsMultiregional biopsies from stage II and III CRC tumors were analyzed by RNA sequencing (41 biopsies, 14 tumors) and multiplex immune protein analysis (89 biopsies, 29 tumors). CRC subtyping was performed using consensus molecular subtypes (CMS), CRC intrinsic subtypes (CRIS), and TUMOR types. ITH-scores and network maps were defined to determine the origin of heterogeneity. A validation cohort was used with one biopsy per tumor (162 tumors).ResultsOverall, inter-tumor transcriptional variation exceeded ITH, and subtyping calls were frequently concordant between multiregional biopsies. Still, some tumors had high transcriptional ITH and were classified discordantly. Subtyping of proximal MSS tumors were discordant for 50% of the tumors, this ITH was related to differences in the microenvironment. Subtyping of distal MSS tumors were less discordant, here the ITH was more cancer-cell related. The subtype discordancy reflected actual molecular ITH within the tumors. The relevance of the subtypes was reflected at protein level where several inflammation markers were significantly increased in immune related transcriptional subtypes, which was verified in an independent cohort (Wilcoxon rank sum test; p<0.05). Unsupervised hierarchical clustering of the protein data identified large ITH at protein level; as the multiregional biopsies clustered together for only 9 out of 29 tumors.ConclusionOur transcriptomic and proteomic analyses show that the tumor location along the colorectum influence the ITH of CRC, which again influence the concordance of subtyping.

Project description:Colorectal cancer arises in part from the cumulative effects of multiple gene lesions. Recent studies in selected cancer types have revealed significant intra-tumor genetic heterogeneity and highlighted its potential role in disease progression and resistance to therapy. We hypothesized the existence of significant intra-tumor genetic heterogeneity in rectal cancers involving variations in localized somatic mutations and copy number abnormalities. Two or three spatially disparate regions from each of six rectal tumors were dissected and subjected to the next-generation whole-exome DNA sequencing, Oncoscan SNP arrays, and targeted confirmatory sequencing and analysis. The resulting data were integrated to define subclones using SciClone. Mutant-allele tumor heterogeneity (MATH) scores, mutant allele frequency correlation, and mutation percent concordance were calculated, and copy number analysis including measurement of correlation between samples was performed. Somatic mutations profiles in individual cancers were similar to prior studies, with some variants found in previously reported significantly mutated genes and many patient-specific mutations in each tumor. Significant intra-tumor heterogeneity was identified in the spatially disparate regions of individual cancers. All tumors had some heterogeneity but the degree of heterogeneity was quite variable in the samples studied. We found that 67-97% of exonic somatic mutations were shared among all regions of an individual's tumor. The SciClone computational method identified 2-8 shared and unshared subclones in the spatially disparate areas in each tumor. MATH scores ranged from 7 to 41. Allele frequency correlation scores ranged from R(2)=0.69-0.96. Measurements of correlation between samples for copy number changes varied from R(2)=0.74-0.93. All tumors had some heterogeneity, but the degree was highly variable in the samples studied. The occurrence of significant intra-tumor heterogeneity may allow selected tumors to have a genetic reservoir to draw from in their evolutionary response to therapy and other challenges.

Project description:Colorectal cancer (CRC) ranks as the second leading cause of cancer-related mortality globally and is the third most prevalent cancer. The effective treatment of CRC is challenged by tumor drug resistance, underscoring the urgent need for novel therapeutic strategies. It is well recognized that epigenetic modifications, particularly DNA methylation, significantly contribute to the initiation and advancement of CRC. Tumors frequently exhibit hypermethylation of specific gene promoters alongside a general hypomethylation of genomic DNA. In normal tissues, gene promoters, particularly those of tumor suppressor genes, are typically unmethylated, whereas they are often hypermethylated in cancerous tissues. Previous studies have identified the methylation status of the CpG island within the SLC30A10 gene as a reliable biomarker for CRC. Notably, a hypermethylated phenotype is inversely correlated with SLC30A10 expression. However, the precise functional implications of SLC30A10 suppression in the context of CRC progression remain to be elucidated.). The investigation of molecular pathways involved in metal metabolism in CRC has not been conducted previously at the transcriptomic level. Furthermore, the relationship between the mutational characteristics of tumors—such as individual mutations, mutational burden, and microsatellite instability—and the activity of genes related to metal metabolic pathways has not been explored. This project aims to be the first to examine the antitumor potential of modulating the transport systems for manganese and zinc ions in CRC. The molecular function of SLC30A10 is to export zinc (Zn) and manganese (Mn) ions from the cell. Additionally, SLC30A10 plays a crucial role in mitigating Mn-induced cytotoxicity and facilitates Zn transport to early endosomes while promoting endosomal recirculation to avert Zn toxicity. Our findings indicate that overexpression of SLC30A10 is correlated with the knockout of its functional antagonist, SLC39A14 in the HuTu80 and HCT-15 cell lines.

Dataset Information

Gender-related prognostic value and genomic pattern of intra-tumor heterogeneity in colorectal cancer.

Publications

Gender-related prognostic value and genomic pattern of intra-tumor heterogeneity in colorectal cancer.

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