PINCH2, a subset of IPP complex, a cancer metastasis-related copy number variant with paracrine activity in colon cancer

Abstract

Up to now, genomic variability has been reported in human genomes. Copy number variants (CNVs) represent a copy number change involving a DNA fragment that is ∼1 kilobases (kb) or larger. Although almost 40% of cancer-related genes are interrupted by CNVs, very few studies have reported on the correlation between CNVs and cancer. Genome-wide arrays provided a more comprehensive analysis of the entire genome. We screened colon cancer metastasis-related CNVs using array-CGH, and investigated the functional mechanism of the selected CNV with in silico and in vitro assay. We used 41 normal colon tissues from stage III colon cancer patients composed of 22 patients who had been disease-free for over 5 years and 19 relapsed patients within 3 years after surgery. In total, 1,359 CNVs showed different aberration patterns between patients whose cancer recurred and those whose cancer did not recur. From 1,359 CNVs, we selected 89 cancer metastasis-related CNVs consisting of cancer migration/invasion pathways, cellular movement-related pathways, and cell-to-cell signaling and interaction pathways. Noticeably, PINCH2 showed copy number amplification and up-regulation of mRNA expression in the non-recurred group. PINCH2 is known to regulate cancer cell movement participating in the IPP complex (ILK, PARVA, and PINCH), which is related to cellular movement pathway. In the in vitro experiment, five colon cancer cells had a lower protein and mRNA expression of PINCH2 as compared to the three normal epithelial colon cells. PINCH2 had a higher binding affinity with ILK than PINCH1 in both in silico and in vitro analyses. The PINCH2-ILK complex reduced the expression of MMP-9 metalloprotenase with decreased cell migration and invasion activity. Also, the migration rates of both PINCH2 suppressed HCT-116 cells (autocrine) and cells treated with conditioned media (CM) of PINCH2 suppressed HCT-116 cells (paracrine) increased. In conclusion, PINCH2, a cancer metastasis-related CNV, is associated with cancer cell migration and invasion as an autocrine and paracrine activity in cancer by regulating IPP complex formation.