Conclusions
TPM4 overexpression attenuates colon epithelial cell differentiation and promotes proliferation. Therefore, TPM4 expression may be a biomarker to enhance strategies for CRC diagnosis and treatment.
Methods
We searched for contractility- and motility-related genes that are dysregulated in human CRC relative to normal colon. RNA expression of one such gene, tropomyosin 4 (TPM4), was measured by qRT-PCR and RNA-seq in human colorectal tissues at various stages of tumorigenesis: CRC, adenoma, and at-risk (grossly normal mucosa from a patient with Familial Adenomatous Polyposis, or FAP), relative to controls. Effects of aberrant TPM4 expression on colon epithelial cell proliferation and maturation were determined by overexpression using stable transfection in spontaneously differentiating Caco2 cells or silencing using siRNA in proliferating cells.
Objective
The high morbidity and mortality associated with colorectal cancer (CRC) and the recent increases in early-onset CRC obviate the need for novel
Results
TPM4 is overexpressed at various stages of tumorigenesis, including CRC, adenoma, and grossly normal FAP colon tissue, as well as in proliferating versus differentiating Caco2 cells. TPM4.2 overexpression in differentiating Caco2 cells markedly inhibits certain aspects of maturation, notably sucrase isomaltase and glutathione-S-transferase alpha1 expression, and causes morphological and cell junction abnormalities. Conversely, siRNA-mediated suppression of TPM4.2 inhibits Caco2 proliferation. Conclusions: TPM4 overexpression attenuates colon epithelial cell differentiation and promotes proliferation. Therefore, TPM4 expression may be a biomarker to enhance strategies for CRC diagnosis and treatment.