Birt-Hogg-Dube syndrome (BHD) is an autosomal dominant neoplasia syndrome characterized mainly by benign skin tumors, and to a lesser extent, renal tumors and spontaneous pneumothorax. To map the BHD locus, we performed a genome-wide linkage analysis using polymorphic microsatellite markers on a large Swedish BHD family. Evidence of linkage was identi®ed on chromosome 17p12-q11.2, with a maximum LOD score of 3.58 for marker D17S1852. Further haplotype analysis de®ned a *35 cM candidate interval between the two¯anking markers, D17S1791 and D17S798. This information will facilitate the identi®cation of the BHD gene, leading to the understanding of its underlying molecular etiology. Oncogene (2001) 20, 5239 ± 5242.

We have studied 25 cases of squamous cell carcinoma in chronic venous leg ulcers. Twenty-three of the patients were dead and two were alive. The mean age at cancer diagnosis was 78.5 years. The median survival was 1 year. Eleven tumours were well-differentiated, 10 moderately and four poorly. All patients with a poorly differentiated tumour died within a year. Metastases were certain in eight cases. The disease was lethal in 10 cases which included all poorly differentiated tumours. The survival of the study group was significantly shortened compared with a control group of patients with lower limb non-melanoma skin cancer (n = 433) from the Swedish Cancer Registry (P = 0.0084). When diagnosed, squamous cell carcinoma in chronic leg ulcers merits a thorough investigation of the degree of differentiation and spread. Assertive treatment is indicated as poorly differentiated tumours and some moderately differentiated tumours may be fatal.

Basal cell carcinoma (BCC) of the skin represents the most common malignancy in humans. MicroRNAs (miRNAs), small regulatory RNAs with pleiotropic function, are commonly misregulated in cancer. Here we identify miR-203, a miRNA abundantly and preferentially expressed in skin, to be downregulated in BCCs. We show that activation of the Hedgehog (HH) pathway, critically involved in the pathogenesis of BCCs, as well as the EGFR/MEK/ERK/c-JUN signaling pathway suppresses miR-203. We identify c-JUN, a key effector of the HH pathway, as a novel direct target for miR-203 in vivo. Further supporting the role of miR-203 as a tumor suppressor, in vivo delivery of miR-203 mimics in a BCC mouse model results in the reduction of tumor growth. Our results identify a regulatory circuit involving miR-203 and c-JUN, which provides functional control over basal cell proliferation and differentiation. We propose that miR-203 functions as a ‘bona fide' tumor suppressor in BCC, whose suppressed expression contributes to oncogenic transformation via derepression of multiple stemness- and proliferation-related genes, and its overexpression could be of therapeutic value.

Solid organ transplant recipients have a high incidence of cutaneous squamous cell carcinoma and often develop multiple and aggressive tumours. This retrospective study based on the Swedish organ transplant cohort, focuses on the deaths caused by cutaneous squamous cell carcinoma and aims to elucidate the clinicopathological features of these tumours. The cohort comprised 5931 patients who underwent organ transplantation during the period 1970 to 1997 and were registered in the Swedish In-patient Registry, Cancer Registry and Causes-of-Death Registry. A total of 544 cutaneous squamous cell carcinomas in 201 patients were re-examined. The dominating size of the tumours was 5-10 mm and one-third of the tumours were removed by methods other than excision surgery. Well-differentiated tumours and Clark level IV were predominant. Seven patients died from their tumours, all of which were localized on the head. The principal site of metastasis was the parotid gland. The mean duration between date of transplantation and death was 10.4 years (range 6-17 years). Mortality from cutaneous cell carcinoma was compared with that of the general population. There was a highly increased risk; standardized mortality ratio 52.2; 95% confidence interval 21.0-107.6. However, the mortality rate in the Swedish cohort appears to be lower than what has been reported previously from other countries.

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