BMI1 expression identifies subtypes of Merkel cell carcinoma

Merkel cell carcinoma: is this a true carcinoma?

Recent years have brought an enhanced understanding of Merkel cell carcinoma (MCC) biology, especially with regard to the Merkel cell polyoma virus as a causative agent. Differences between Merkel cell polyomavirus-positive and Merkel cell polyomavirus-negative MCC in morphology; gene expression, miRNA profiles and prognosis have been reported. Origin of MCC is controversial. Presence of neurosecretory granules has suggested that these carcinomas originate from one of the neurocrest derivatives, most probably Merkel cells; the name Merkel cell carcinoma is now widely accepted. Expression of PGP 9.5, chromogranin A and several neuropeptides, initially regarded as specific markers for neural and neuroendocrine cells, has recently been shown in a subset of lymphomas. MCC commonly expresses terminal deoxynucleotidyl transferase and PAX5. Their co-expression under physiologic circumstances is restricted to pro/pre-B cells and pre-B cells. These findings lead to the hypothesis by zur Hausen et al. that MCC originates from early B cells. This review was intended to critically appraise zur Hausen's hypothesis and discuss the possibility that MCC is a heterogenous entity with distinct subtypes.

BMI1 and TWIST1 downregulated mRNA expression in basal cell carcinoma

BACKGROUND

BMI1, TWIST1 and SNAI2/SLUG have been implicated in aggressive behavior of squamous cell carcinoma (SCC) and melanoma and BMI1 expression could identify subtypes of Merkel cell carcinoma (MCC). However, BMI1, TWIST1 and SNAI2 expression levels in basal cell carcinomas (BCCs) have not been elucidated. We hypothesized BCC could be a good model system to decipher mechanisms which inhibit processes that drive tumor metastasis. The aim of this study was to examine the mRNA expression level of BMI1, TWIST1, and SNAI2 in BCCs.

MATERIALS AND METHODS

Thirty-five fresh non-metastatic BCC tissue samples and seven fresh normal skin tissue samples were evaluated by real-time RT-PCR.

RESULTS

BMI1 and TWIST1 demonstrated marked down-regulation (p<0.00l, p=0.00l respectively), but SNAI2 showed no significant change (p=0.12).

CONCLUSIONS

Previous literature has clearly demonstrated a positive association between BMI1 and TWIST1 expression and metastatic BCC, aggressive SCC and melanoma. Here, we demonstrated a negative association between BMI1 and TWIST1 mRNA expression level and BCC.

miRNA-34a underexpressed in Merkel cell polyomavirus-negative Merkel cell carcinoma

Merkel cell polyomavirus (MCV) is frequently detectable in Merkel cell carcinoma (MCC) tumors, but the significance of MCV infection is not yet totally understood. Thus far, no key regulatory miRNA has been identified for MCC tumorigenesis. However, distinct miRNA expression profiles have been suggested for MCV-positive and MCV-negative tumors. We used microarray hybridization to identify miRNA expression differences in MCC tumor samples according to MCV status and further validated these results by quantitative reverse transcription polymerase chain reaction (qRT-PCR). When compared with MCV-negative tumors, we detected overexpression of miR-34a, miR-30a, miR-142-3p, and miR-1539 in those MCV positives. In addition, slight underexpression was detectable in MCV-positive tumors of miR-181d. We confirmed the distinct expression of miRNAs in MCV-positive and MCV-negative tumors and confirmed statistically significant underexpression of miR-34a in MCV-negative tumors by both array analysis and qRT-PCR. Neither tumor location nor development of metastases affected miRNA expression.

Merkel cell carcinoma - recent advances in the biology, diagnostics and treatment

Merkel cell carcinoma (MCC) is an uncommon primary cutaneous carcinoma with neuroendocrine differentiation. Since recent discovery of MCCs strong association with Merkel cell polyomavirus (MCPyV), there has been a rapid increase in the understanding of the carcinomas genetics, molecular biology and pathogenesis. In our study, we reviewed recent advances and controversies concerning MCC histogenesis, epidemiology, diagnostic and prognostic markers. We analyzed the association of MCPyV with MCC and the possible new targets for therapy. We also examined English-based literature regarding MCC pathogenesis published between 2008 and 2013, which lead to a deeper understanding of the topic. Our study showed that the association of MCPyV strongly influences the course of MCC. Additionally, it has been shown that a immunological response to MCPyV may in the future give hope to identify new therapeutic strategies in treatment of this fatal malignancy. This article is part of a Directed Issue entitled: Rare Cancers.