Whole-exome Sequence Analysis of Gastric-type Adenocarcinoma of the Uterine Cervix and Adjacent Lobular Endocervical Glandular Hyperplasia in the Same Case

Abstract

Lobular endocervical glandular hyperplasia (LEGH) may be a precursor lesion of gastric-type adenocarcinoma of the uterine cervix (GAS). However, the genetic mechanisms underlying its carcinogenesis remain unclear. To elucidate the oncogenic process from LEGH to GAS, we compared gene mutations in early-stage GAS and adjacent LEGH in the same case. Fresh-frozen tissue sections were obtained from a patient with Stage IB3 GAS and adjacent LEGH who had undergone hysterectomy. Using laser microdissection, we harvested the LEGH and GAS portions separately from these sections and extracted the genomic DNA. Somatic variant analysis using whole-exome sequencing used DNA from the normal myometrium as a reference sequence. Somatic variants involving amino acid substitutions were detected in 61 and 125 locations in LEGH and GAS, respectively. Seven variants were common in both lesions, of which the pathogenic variant was GNAS only (c.2531G>A, p.R844H), a mutation frequently reported in pancreatic and colorectal cancers. LEGH had no other pathogenic variants; another pathogenic variant in GAS was found only at the same amino acid site as GNAS (c.2530C>T, p.R844C). In the present case, LEGH and GAS shared the same pathogenic variant of GNAS, indicating that both lesions had a common origin. Furthermore, the current results showed that the second GNAS variant is associated with the progression of LEGH to GAS. Further studies are required to elucidate GAS’s pathogenesis and biological characteristics.