CHAMP1 expression is upregulated in cancer and supports cell growth

概要

CHAMP1 (chromosome alignment-maintaining phosphoprotein 1) is a novel protein involved in chromosome alignment in mitosis and mutated in individuals with intellectual disability. It was also reported that CHAMP1 promotes cell survival through maintaining the expression of anti-apoptotic Bcl-2 family proteins, especially Mcl-1. Here I investigated the role of CHAMP1 in cancer cell growth. Searching cancer databases, I found that CHAMP1 mRNA expression is upregulated in many cancer types, which was confirmed at the protein level by immunohistochemistry of cancer tissues. Increased CHAMP1 mRNA expression was also correlated to poor prognosis in several cancers. In contrast, point mutations of CHAMP1 gene were infrequent and not confined to a specific region. CHAMP1 protein expression was higher in many cancer cell lines than non-transformed cell lines, concomitant with high anti-apoptotic Bcl-2 family proteins expression. Then I addressed the role of CHAMP1 in cell growth by MTT assay and colony formation assay, and found that CHAMP1-depletion reduces cell growth in both non-transformed and cancer cell lines. Chromosome misalignment was seen in a subset of CHAMP1-depleted cancer cell lines, while defects in homologous recombination repair were found in all the cell lines examined. My data demonstrate that upregulation of CAHMP1 expression is widely seen in cancer, and suggest that CHAMP1 expression supports cell survival.