Increased expression of calpain 6 during the progression of uterine cervical neoplasia: immunohistochemical analysis.

Calpain 6 (Capn6) is one of the calcium-dependent intracellular nonlysosomal proteases and is known for tissue-specific expression, primarily in the placenta. We investigated whether the expression of Capn6 is associated with the progression of uterine cervical neoplasia. We analyzed 81 formalin-fixed paraffin-embedded cervical tissues that included six normal cervical epithelium, 20 low-grade squamous intraepithelial lesions (LSIL), 17 high-grade squamous intraepithelial lesions (HSIL), 20 invasive squamous cell carcinomas (ISCC) without lymph node (LN) metastasis and 18 ISCCs with LN metastasis. The expression of Capn6 was determined by immunohistochemistry and was undetectable in normal cervical squamous epithelium. The expression of the protein gradually increased in accordance with the progression from normal to LSIL (P=0.000) and from LSIL to HSIL (P=0.003). Capn6 was detected in all cases of ISCC. However, there was no significant difference between HSIL and ISCC (P=0.945), ISCC with LN metastases and ISCC without LN metastases (P=0.862). The distribution of staining was diffuse. The cytoplasm and nucleus were stained evenly. These results suggest that Capn6 may play a significant role in the development of LSIL and may also function in the progression of LSIL to HSIL. However, its role in tumor development and metastases is not clear.