Calretinin is a Ca<sup>2+</sup>-binding protein expressed during MM tumorigenesis that activates the FAK signaling pathway, promoting invasion and epithelial-to-mesenchymal transition.
Calretinin (CR; <i>CALB2</i>) belonging to the family of EF-hand Ca<sup>2+</sup>-binding proteins (CaBP) is widely used as a positive marker for the identification of human malignant mesothelioma (MM) and functionally was suggested to play a critical role during carcinogenesis of this highly aggressive asbestos-associated neoplasm.
We evaluated immunohistochemical markers of sex-steroid differentiation and steroidogenesis (calretinin, inhibin, steroidogenic factor 1), steroid enzymes involved in hormone biosynthesis (CYP17, CYP19, HSD17β1, AKR1C3), and hormone receptors (estrogen receptor, progesterone receptor, and androgen receptor) in 101 epithelial ovarian tumors and in normal structures implicated in ovarian carcinogenesis (ovarian surface epithelium and cortical inclusion cysts) in an attempt to elucidate this process.
Calretinin (CR) is widely used as a diagnostic marker for epithelioid and mixed (biphasic) mesothelioma; however, little is known about CR's putative functions in tumorigenesis.
Our results indicate that C/T heterozygosity at position 513 is linked to CR expression in colon tumors and colon cancer cell lines, suggesting a link with increased carcinogenesis.
It is suggested that calretinin is active in the first steps of carcinogenesis in all human mesotheliomas and during several stages in the evolution towards malignancy.
This implicates that expression of CR and/or CR-22k in colon tumor cells may contribute to tumorigenesis by blocking differentiation-promoting signals.