Patched 1 expression in Merkel cell carcinoma.

The relevance of Hedgehog signaling in Merkel cell carcinoma has only been addressed by a few studies with conflicting results. Thus, we aimed to establish the expression of Hedgehog signaling molecules in Merkel cell carcinoma to characterize causes of aberrant expression and to correlate these findings with the clinical course of the patients. Immunohistochemistry was performed for Sonic, Indian, Patched 1 (PTCH1) and Smoothened on patients' tumor tissue. Respective mRNA expression was analyzed in 10 Merkel cell carcinoma cell lines using quantitative real-time polymerase chain reaction. PTCH1 sequencing and DNA methylation microarray analyses were carried out on tumor tissues as well as cell lines. PTCH1 immunoreactivity in Merkel cell carcinoma was similar to that of basal cell carcinomas, which both significantly differed from PTCH1 immunoreactivity in healthy skin. Most PTCH1 mutations found were synonymous or without known functional impact. However, on average, the promoter regions of both PTCH1 were hypomethylated independently from PTCH1 gene expression or Merkel cell polyomavirus status. PTCH1 and GLI1/2/3 genes were differently expressed in different cell lines; notably, there was a significant correlation between GLI2 and PTCH1 mRNA expression. Similar to PTCH1 protein expression in patient tissues, PTCH1 gene expression in Merkel cell carcinoma cell lines is highly variable, but due to the similar methylation pattern across Merkel cell carcinoma cell lines, effects other than methylation seem to be the reason for the differential expression and PTCH1 appears to be upregulated by GLI as a classical Hedgehog target gene.

Expression of PIWIL3 in primary and metastatic melanoma.

PURPOSE: The PIWI-interacting RNA machinery in malignant melanoma (MM) has not been sufficiently studied. We aimed to investigate the PIWIL3 expression profiles in primary melanomas and metastases of MM including a correlation with clinical data. METHODS: We studied 161 primary melanomas, 45 lymph node metastases, and 16 distant metastases of 183 patients with MM. We used immunohistochemistry to assess PIWIL3 protein expression in situ. The relationship between the immunoreactivity of PIWIL3 and clinical data was statistically evaluated. RESULTS: We observed a significantly (P = 0.000059) higher median immunoreactivity score in primary melanomas (4.9; range, 0.1-6), lymph node metastases (5.1; range, 3.3-6), and distant metastases (5.6; range, 4.5-6). PIWIL3 was expressed significantly higher (P = 0.0002) in primary nodular melanomas and acral melanomas (5.2; range, 3.4-6) when compared to other melanoma subtypes (4.7; range, 0.1-6). On univariate analysis, a significant positive correlation was observed between primary melanoma PIWIL3 expression and tumor thickness (r = 0.2; P = 0.014). On univariate and multivariate analysis, PIWIL3 did not prove to be an independent predictor for melanoma relapse or death. CONCLUSIONS: Our data indicate that PIWIL3 protein expression is elevated in more aggressive primary MM and metastatic disease. As also observed in other malignancies, PIWIL3 seems to play a role in MM progression.