Isolation and characterization of the novel human gene, MOST-1

Abstract

Using PCR with human papillomavirus E6 gene primers, a novel human intronless gene MOST-1 was isolated from MOLT-4 T-lymphoblastic leukemia cell line. A potential ORF with an ideal Kozak, encodes a putative hydrophilic polypeptide of 99 amino acids. Computational analysis showed 3 mRNA destabilizing signals at its 3a?? UTR, protein to be unstable and non-globular with a secondary structure mainly of extended sheets. MOST-1 is expressed in all 19 cancer and 2 normal cell lines tested and differential expression in 9 out of 16 normal tissues. MOST-1 was mapped by FISH to chromosome 8q24.2, a region amplified in breast and prostate cancers. Analysis of paired biopsies of invasive ductal breast cancer and adjacent normal tissue revealed MOST-1 mRNA to be two-fold greater in grade 3 compared with grade 1 and 2 cancers. Quantitative real-time PCR of archival prostatic biopsies displayed 9.9, 7.5, 4.2 and 1.4 higher MOST-1 DNA levels respectively in high, intermediate, low grade carcinomas and benign hyperplasias compared to normal. A polyclonal antibody which recognize aggregated form of MOST-1 protein was raised. Confocal immunofluorescence microscopy showed punctuate pattern of MOST-1 in normal and cancer mammary and prostate cell lines. Knock down experiments via RNAi suggest role in cancer cells proliferation. Y2H screening revealed interactions with 7 proteins which are reported to be amplified or deregulated in tumors and involved in cell cycle or energy metabolism. Co-immunoprecipitation validated interactions. Taken together, MOST-1 appears to be involved in cancer progression suggesting a mitogenic function.