Mutation of NRAS is a Rare Genetic Event in Ovarian Low-Grade Serous Carcinoma

Publication date: Available online 2 September 2017
Source:Human Pathology
Author(s): Deyin Xing, Yohan Suryo Rahmanto, Felix Zeppernick, Charlotte G. Hannibal, Susanne K. Kjaer, Russell Vang, Ie-Ming Shih, Tian-Li Wang
Activating mutations involving the members of the RAS signaling pathway, including KRAS, NRAS, and BRAF, have been reported in ovarian low-grade serous carcinoma and its precursor lesion, serous borderline tumor (SBT). Whether additional genetic alterations in the RAS oncogene family accumulate during the progression of serous borderline tumor (SBT) to invasive low grade serous carcinoma (LGSC) remains largely unknown. While mutations of KRAS and BRAF occur at a very early stage of progression, even preceding the development of SBT, additional driving events, such as NRAS mutations, have been postulated to facilitate progression. In this study, we analyzed NRAS exon 3 mutational status in 98 cases that were diagnosed with SBT/atypical proliferative serous tumor (SBT/APST), non-invasive LGSC (niLGSC), or invasive LGSC (iLGSC). Of the latter, NRAS Q61R (CAA to CGA) mutations were detected in only 2 of 56 (3.6%) cases. The same mutation was not detected in any of the SBT/APSTs or niLGSCs. Mutational analysis for hotspots in KRAS and BRAF demonstrated a wildtype pattern of KRAS and BRAF in one of the NRAS-mutated cases. Interestingly, another LGSC case with NRAS mutation harbored a concurrent BRAF V600L mutation. These findings indicate that, although recurrent NRAS mutations are present, their low prevalence indicates that NRAS plays a limited role in the development of LGSC. Further studies to identify other oncogenic drivers of LGSC progression is warranted.



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