Abstract 2879: MACC1 overexpression in colorectal cancer is driven by chromosomal instability and is associated with molecular subtype
Authors: Vuaroqueaux Vincent , Al-Hasani Hoor , Kobelt Dennis , Risch Thomas , Burock Susen , Yaspo Marie-Laure , Fiebig Heinz-Herbert , Stein Ulrike 
Published: July 2021

Abstract
Metastasis-Associated in Colon Cancer 1 (MACC1) is a strong prognostic marker for human colorectal cancers (CRC). The gene is a key regulator of the HGF/c-Met pathway and its overexpression is associated with cancer cell proliferation, migration, invasiveness and metastasis. The contexture of MACC1 overexpression in cancers is still poorly understood. Here we used the data released by The Cancer Genome Atlas (TCGA) and in silico approaches for a deep and integrative analysis of MACC1 expression modalities in CRCs.
First, we curated COAD-READ TCGA datasets and obtained full clinical, genomic, and transcriptomic annotation for a total of 259 CRC samples. In tumors, we showed high heterogeneity of MACC1 mRNA expression levels with data varying from 5.58 to 13.07 U (RNAseq log transformed data - RSEM normalized). By correlating MACC1 expression to clinical data, we showed its levels were associated with anatomic regions of the disease (p=6.35.10-5). The tumors from descending colon and rectum having higher levels than those of the ascending colon and caecum (p=7.44-06). High MACC1 was also associated with higher tumor stages (p=0.01) and nodal invasion (p=0.03). At genomic level, MACC1 mutation was not frequent in CRCs (&lt;2%). The gene is however frequently subjected to gene copy number variation (CNV) due to chromosomal instability and polyploidy (MACC1 CNV values &gt; normal in 155/259: 60%). Correlation analysis indicated strong positive association between MACC1 copy number variations and mRNA expression levels (p&lt;10-16). In an independent dataset, we validate that gain of MACC1 gene copy number and associated higher expression levels correlated with metastasis dissemination and worse outcome of the patients. By analyzing MACC1 with respect of CRC subtypes, we confirmed higher MACC1 levels in MSS tumors with high chromosomal instability (CIN) compared to MSI or genomic stable tumors (GS) (p=1.16-14). Regarding association with CMS1-4 transcriptomic subtypes, the highest expression of MACC1 were observed in CMS2-(epithelial), and CMS4 (mesenchymal) as compared with CMS3 (epithelial with metabolic dysregulation) or CMS1 (MMR deficient). The subset of tumors with very low MACC1 expression were mainly those altered for MLH1 (MSI-H- MMR tumors), notably most of them have normal ploidy. Deconvolution analysis of immune contexture revealed negative correlation between MACC1 expression and immune activation. Stratification using MACC1 as prognostic marker within these tumor types will be evaluated and the gene will also be presented with respect of alterations of key cancer genes in these tumors. Overall, the present study gives insight into the contexture of MACC1 expression in CRC. We showed MACC1 overexpression is largely driven by chromosomal instability and DNA copy number gains. Its expression was dependent on the tumor molecular subtypes.
Citation Format: Vincent Vuaroqueaux, Hoor Al-Hasani, Dennis Kobelt, Thomas Risch, Susen Burock, Marie-Laure Yaspo, Heinz-Herbert Fiebig, Ulrike Stein. MACC1 overexpression in colorectal cancer is driven by chromosomal instability and is associated with molecular subtype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2879.