Emerging evidence indicates that
serine proteases of the
tissue kallikrein-related
peptidases family (KLK) are implicated in
tumorigenesis. We recently reported the ectopic expression of KLK4 and KLK14 in
colonic cancers and their signaling to control cell proliferation. Human
tissue kallikrein-related
peptidase 7 (KLK7) is often dysregulated in many
cancers; however, its role in colon
tumorigenesis has not yet been established. In the present study, we analyzed expression of KLK7 in 15
colon cancer cell lines and in 38 human colonic
tumors. In many human
colon cancer cells, KLK7
mRNA was observed, which leads to KLK7
protein expression and secretion. Furthermore, KLK7 was detected in human
colon adenocarcinomas, but it was absent in normal epithelia. KLK7 overexpression in HT29
colon cancer cells upon stable transfection with a KLK7 expression plasmid resulted in increased cell proliferation. Moreover, subcutaneous inoculation of transfected cells into nude mice led to increased
tumor growth that was associated with increased
tumor cell proliferation as reflected by a positive Ki-67 staining. Our results demonstrate the aberrant expression of KLK7 in
colon cancer cells and tissues and its involvement in cell proliferation in vitro and in vivo. Thus, KLK7 may represent a potential therapeutic target for human colon
tumorigenesis.