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Elsevier, Human Pathology

DOI: 10.1016/j.humpath.2015.12.015

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Porocarcinomas harbor recurrent HRAS activating mutations and tumor suppressor inactivating mutations

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This paper is available in a repository.

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Data provided by SHERPA/RoMEO

Abstract

Porocarcinomas are a rare eccrine carcinoma with significant metastatic potential. Oncogenic drivers of porocarcinomas have been underexplored, with PIK3CA activating mutation reported in one case. We analyzed 5 porocarcinomas by next generation sequencing using the DNA component of the Oncomine Comprehensive Assay (OCP), which provides data on copy number changes and mutational events in 126 cancer-relevant genes through multiplex PCR. We detected an average of 3.3 high-confidence nonsynonymous mutations per tumor (range: 1-6), including a spectrum of oncogenic activation and tumor suppressor inactivation events. Tumor suppressor mutations included TP53 (4/5, 80%), RB1 (3/5, 60%), ATM (2/5, 40%), ARID1A (1/5, 20%) and CDKN2A (1/5, 20%). In 4/5 (80%) tumors, at least one potential oncogenic driver was identified. Activating HRAS mutations were detected in 2/5 (40%), including G13D and Q61L hotspot mutations. Mutations of EGFR were identified in 2/5 (40%); these mutations have been previously reported in cancer but did not affect classic activation hotspot sites. EGFR and HRAS mutations were mutually exclusive. HRAS mutations were detected by targeted sequencing in a minority of benign eccrine poromas (2/17, 11.7%), suggesting HRAS activation may rarely be an early event in sweat gland neoplasia. Together, our data suggest roles for HRAS and EGFR as drivers in a subset of poroma and porocarcinoma. TP53 and RB1 inactivation events are also likely to contribute to tumorigenesis. These findings suggest that porocarcinomas display diversity with respect to oncogenic drivers, which may have implications for targeted therapy in metastatic or unresectable cases.