Temporal activation of WNT/ß-catenin signaling is sufficient to inhibit SOX10 expression and block melanoma growth.

Despite advances in the systemic treatment of patients with metastatic melanoma using immune checkpoint and tyrosine kinase inhibitors (TKI), the majority of stage IV melanoma patients eventually succumb to the disease. We have previously identified the transcription factor Sox10 as a crucial player in melanoma, yet the underlying molecular mechanisms mediating Sox10-dependent tumorigenesis remain largely uncharacterized. Here, we show that MEK and RAF inhibitors do not suppress levels of SOX10 protein in patient-derived cells in vitro, as well as in melanoma patients in vivo. In a search for pharmacological inhibitors of SOX10, we performed a mass spectrometry-based screen in human melanoma cells. Subsequent analysis revealed that SOX10 directly interacts with ß-catenin, which is a key mediator of canonical Wnt/ß-catenin signaling. We demonstrate that inhibitors of glycogen synthase kinase 3 alpha/beta (GSK3α/ß) efficiently abrogate SOX10 protein in human melanoma cells in vitro and in melanoma mouse models in vivo. The mechanism of action of GSK3-mediated SOX10 suppression is transcription-independent and relies on the presence of a proteasome degradable form of ß-catenin. Taken together, we provide evidence that activation of canonical Wnt signaling has a profound effect on melanoma growth and is able to counteract Sox10-dependent melanoma maintenance both in vitro and in vivo.

Oropharyngeal lesions and cervical lymphadenopathy: syphilis is a differential diagnosis that is still relevant.

BACKGROUND: Syphilis (lues), a chronic infectious disease caused by Treponema pallidum, has been increasing in incidence during the last few years. Therefore, while clinically it is often not suspected, syphilis is increasingly becoming a differential diagnosis in routine pathology. AIM: To report our experience with five cases of cervical lymphadenopathy and/or oropharyngeal lesions, clinically thought to be lymphomas, lymph node metastases or carcinoma, in which we made the mostly clinically unsuspected diagnosis of syphilis. METHODS: Fine needle aspiration of enlarged cervical lymph nodes was evaluated by cytology and flow cytometry (fluorescence-activated cell sorting analysis), and biopsies were examined by using histology. In addition, all materials were also subjected to immunostaining, silver staining and molecular (PCR) testing. RESULTS: Fine needle aspiration cytology revealed follicular hyperplasia in two cases and granulomatous lymphadenitis in one case. In three patients, concomitant biopsy of co-existing oropharyngeal lesions revealed histological findings compatible with syphilis. T pallidum was detected in all cytological and histological samples by immunohistochemistry/immunocytochemistry and PCR. Subsequently, a diagnosis of syphilis was confirmed clinically and by serology. CONCLUSIONS: Syphilitic lymphadenitis is still a relevant differential diagnosis of cervical lymphadenopathy, and it is clinically often not suspected. Co-existing oropharyngeal lesions should alert the physician to this differential diagnosis; and lesions with compatible morphology should be tested with immunohistochemistry and immunocytochemistry and/or molecular analysis to confirm the diagnosis of syphilis.

The immunohistochemistry of invasive and proliferative phenotype switching in melanoma: a case report.

To date there is no effective therapy for metastatic melanoma and at the molecular level the disease progression is poorly understood. A recent study by our group led to the development of a novel phenotype switching model for melanoma progression, wherein cells transition back-and-forth between states of proliferation and invasion to drive disease progression. To explore the model's clinical relevance we interrogated phenotype-specific expression patterns in human melanoma patient material. A matched primary/metastasis pair from a human melanoma patient was obtained and immunohistochemically stained for proliferative and invasive phenotype markers. These were also stained for hypoxia and blood vessel markers. Proliferative phenotype markers Melan-A and Mitf showed consistent anti-correlation with invasive phenotype marker Wnt5A and hypoxia marker Glut-1. These also correlated with observed intra-tumoural vascularization patterns. Similar pattern distributions were present in both primary and metastasis samples. Strikingly, we observed that late phase metastatic melanoma cells adopt morphologies and behaviours identical to very early phase cells. The expression patterns observed closely matched expectations derived from previous in vitro and xenografting experiments. These results highlight the likelihood that disease progression involves melanoma cells retaining the capacity to regulate the expression of metastatic potential critical factors according to changing microenvironmental conditions.

Reduced pSmad2 immunodetection correlates with increased primary melanoma thickness.

Cutaneous melanoma is the most aggressive of cutaneous neoplasms. Identifying patients with an increased risk for the development of metastases is critical. This study investigates phospho-Smad2, a central factor of the transforming growth factor beta pathway, on formalin-fixed, paraffin-embedded tissues from 60 primary cutaneous melanomas (Breslow >1 mm), for its candidacy for being a prognostic marker in primary cutaneous melanoma. Phospho-Smad2 positivity was assessed for correlation with clinical parameters including Breslow index, melanoma type, survival, development of metastases, sentinel lymph node status and age. Phospho-Smad2 positivity was not associated with survival or development of metastases, suggesting that it would not be a useful prognostic marker. Despite this, we found phospho-Smad2 positivity to be correlated with low tumour thickness, indicating that as the primary tumour grows there is an increased inhibition of transforming growth factor beta signalling resulting in suppressed Smad2 phosphorylation. Additionally, phosphorylation of Smad2 in neighbouring melanoma cells and keratinocytes was interrelated, which is a further indication that Smad2 phosphorylation in primary melanoma is affected by local area microenvironmental factors. We hypothesize that the observed decrease in transforming growth factor beta signalling in thicker primary melanomas is due to the increased production of signalling inhibitors.