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Abstract: The integral membrane channel protein aquaporin (AQP) is aberrantly expressed with oncogenic characteristics in various human cancers. In this study, we analyzed the expression pattern of all subtypes of AQPs, and found that 8 out of 13 AQPs expressed in melanoma cells. To understand the role of aberrant expression of AQP in this disease, we over-expressed AQP3 and AQP9 in human melanoma WM266.4 cells and found that both AQPs significantly increased the chemoresistance of WM266.4 cells to arsenite. Functional studies showed that AQP3 and AQP9 can inhibit cell apoptosis induced by arsenite through down-regulating p53 and up-regulating Bcl-2 and XIAP. Our data suggest the implication of APQ in melanoma progression and that the over-expression of AQP3 and AQP9 contributes to the chemoresistance of melanoma to arsenite. [Copyright &y& Elsevier]

Utilizing gene microarray profiling of melanoma samples, we have recently identified a novel gene overexpressed in both thick primary and metastatic melanomas. This gene, progestagen-associated endometrial protein (PAEP), has never before been implicated in the oncogenic processes of melanoma, with its true function in oncogenesis and tumour progression relatively unknown. Overexpression of the PAEP gene in freshly procured thick primary and metastatic melanoma samples (58%) and daughter cell lines (77%) is confirmed by quantitative RT-PCR, immunohistochemistry, Western blotting and mass spectrometric analysis. We suggest that PAEP gene overexpression is involved with melanoma tumour progression as well as an aggressive phenotype. Transfection of melanoma cells with PAEP small interfering RNA (siRNA) reveals a significant decrease in soft agar colony formation and a marked inhibition of both cell migration and cell invasion. Furthermore, we establish stable melanoma transfectants via PAEP lentiviral small hairpin RNA (shRNA), examine their growth characteristics in a murine xenograft model and reveal that tumour growth is significantly inhibited in two separate melanoma cell lines. Our data strongly implicate the PAEP gene as a tumour growth promoter with oncogenic properties and a potential therapeutic target for patients with advanced melanoma. [ABSTRACT FROM AUTHOR]

The inactivation of tumor-related genes through the aberrant methylation of promoter CpG islands is thought to contribute to tumor initiation and progression. We therefore investigated promoter methylation events involved in cutaneous melanoma by screening 30 genes of interest for evidence of promoter hypermethylation, examining 20 melanoma cell lines and 40 freshly procured melanoma samples. Utilizing quantitative methylation-specific PCR, we identified five genes (SOCS1, SOCS2, RAR-beta 2, TNFSF10C, and TNFSF10D) with hypermethylation frequencies ranging from 50% to 80% in melanoma cell lines as well as freshly procured tissue samples. Eighteen genes (LOX, RASSF1A, WFDC1, TM, APC, TFPI2, TNFSF10A, CDKN2A, MGMT, TIMP3, ASC, TPM1, IRF8, CIITA-PIV, CDH1, SYK, HOXB13, and DAPK1) were methylated at lower frequencies (2–30%). Two genes (CDKN1B and PTEN), previously reported as methylated in melanoma, and five other genes (RECK, IRF7, PAWR, TNFSF10B, and Rb) were not methylated in the samples screened here. Daughter melanoma cell lines showed identical methylation patterns when compared with original samples from which they were derived, as did synchronous metastatic lesions from the same patient. We identified four genes (TNFSF10C, TNFSF10D, LOX, and TPM1) that have never before been identified as hypermethylated in melanoma, with an overall methylation frequency of 60, 80, 50, and 10%, respectively, hypothesizing that these genes may play an important role in melanoma progression. [ABSTRACT FROM AUTHOR]

The proper method of biopsy and definitive surgical excision of cutaneous melanoma is vital for optimal patient outcome. Clearly, the present authors’ understanding of the pathophysiology of cutaneous melanoma continues to change at a rapid pace. Indeed, as the present authors’ research efforts begin to expose some of the mysteries of melanoma, so do they begin to better understand the intricacies of this dreaded cancer. This article will highlight methods of biopsy for melanoma and the management of the primary tumor. The present authors review current recommendations for excision margins for the primary tumor, usefulness of lymphoscintigraphy, timing of definitive surgical excision, and issues unique for head and neck melanoma. [ABSTRACT FROM AUTHOR]

Expression of the pigmentation-associated genePMel17is regulated by a 1 kB promoter region shared between thePMel17andCDK2genes. The encoded melanosomal glycoprotein gp100 and the cell cycle regulatory protein CDK2 are transcribed in opposite directions. Luciferase reporter constructs were generated for subregions of the promoter containing 0, 1, 2 or 3 putative binding sites for transcription factors with basic helix–loop–helix (bHLH) motifs. The potential contribution of bHLH transcription factor microphthalmia transcription factor (MITF) to promoter activity was investigated by re-introducing microphthalmia into melanoma cells lacking expression. A bi-directional reporter construct was generated to investigate potential co-regulation of gp100 and CDK2 transcription. Promoter activity was assessed in presence and absence of phorbol ester tetradecanoyl phorbol 13-acetate (TPA). FACS analysis and immunohistology served to evaluate co-regulation of gp100 and CDK2 expression at the protein level. The full-length promoter, including a consensus binding site for MITF was found to contain sequences that suppressed gp100 expression. Introduction of MITF into non-expressing 1123 melanoma cells did not restore gp100 expression levels. A lack of coregulation for gp100 and CDK2 as suggested by immunostaining was supported by findings of dissimilar expression regulation by TPA for either gene. The current study provides insight into transcriptional regulation of thePMel17andCDK2genes, important to identify strategies for modulating expression of gp100 and CDK2 proteins by melanoma cells. [ABSTRACT FROM AUTHOR]

Utilizing gene microarray profiling of melanoma samples, we have recently identified a novel gene overexpressed in both thick primary and metastatic melanomas. This gene, progestagen-associated endometrial protein (PAEP), has never before been implicated in the oncogenic processes of melanoma, with its true function in oncogenesis and tumour progression relatively unknown. Overexpression of the PAEP gene in freshly procured thick primary and metastatic melanoma samples (58%) and daughter cell lines (77%) is confirmed by quantitative RT-PCR, immunohistochemistry, Western blotting and mass spectrometric analysis. We suggest that PAEP gene overexpression is involved with melanoma tumour progression as well as an aggressive phenotype. Transfection of melanoma cells with PAEP small interfering RNA (siRNA) reveals a significant decrease in soft agar colony formation and a marked inhibition of both cell migration and cell invasion. Furthermore, we establish stable melanoma transfectants via PAEP lentiviral small hairpin RNA (shRNA), examine their growth characteristics in a murine xenograft model and reveal that tumour growth is significantly inhibited in two separate melanoma cell lines. Our data strongly implicate the PAEP gene as a tumour growth promoter with oncogenic properties and a potential therapeutic target for patients with advanced melanoma.