STK11 gene mutations among patients with sporadic breast cancer

Germline mutations affecting STK11 (LRG_319) are profoundly studied in relation to Peutz-Jeghers syndrome, predisposing to the development of various cancers at multiple sites. Though somatic mutations in STK11 are found to be present in several cancers, limited data on its involvement in sporadic breast cancer are available. The present study aims to evaluate the frequency and spectrum of genetic alterations in STK11 in a group of Bulgarian patients with sporadic breast cancer. A total of 73 tumor and 22 corresponding blood specimens derived from the patients, and 10 blood samples from clinically healthy controls were analyzed. High Resolution Melting analysis followed by Sanger sequencing and bioinformatic prediction tools were utilized. Seven patients (9.58%) harbored STK11 alterations, only two (2.74%) of which are exonic: one nonsense c.322A>T; p.K108X (deleterious) and one missense c.440G>A; p.Arg147His (of unknown significance). Two intronic variants were also observed: c.290+36G>T and c. *16+18C>A (novel). To our knowledge the results represent the first data indicating presence of STK11 alterations in patients with sporadic breast cancer. The limited number of the detected deleterious mutations indicates that mutational inactivation of the gene is a rare event and probably plays a minor role in sporadic breast carcinogenesis.