Thrombospondin Type I Domain Containing Protein 1 (THSD1)

THSD1 contains a type 1 thrombospondin domain, which is found in a number of proteins involved in the complement pathway, as well as in extracellular matrix proteins. Alternatively spliced transcript variants encoding different isoforms have been observed for this gene. Quantitative reverse transcription-PCR detected down-regulation of THSD1 expression in 100% of ESCC and other cancer cell lines. Mechanisms for THSD1 silencing in ESCC involved loss of heterozygosity and promoter hypermethylation, as analyzed by methylation-specific PCR and clonal bisulfite sequencing. Transfection of wild-type THSD1 into SLMT-1 resulted in significant reduction of colony-forming ability, hence providing functional evidence for its growth-suppressive activity. These findings suggest that THSD1 is a good candidate TSG.