title: let-7 microRNA expression is reduced in bronchioloalveolar carcinoma, a non-invasive carcinoma, and is not correlated with prognosis.
abstract: It has been proposed that reduced let-7 expression causes RAS expression and correlates with poor survival of lung cancer cases, but little is known about correlations with clinicopathologic features. In this study, we examined 15 early bronchioloalveolar carcinomas (BACs), usually considered as adenocarcinomas in situ, as well as 26 well-differentiated and 25 less-differentiated invasive adenocarcinomas, to assess the association between tumor progression and let-7 expression levels. Additionally, we investigated 47 invasive lung adenocarcinomas for EGFR and KRAS mutations and correlations with let-7 levels. Relative to the corresponding normal lung tissue, reduced let-7 expression was observed in 13 of 15 BACs (87%) and totally in 52 of the 66 adenocarcinomas (79%), suggesting a link with early occurrence in carcinogenesis. On classification of adenocarcinomas into two groups according to let-7 expression, no prognostic or genetic differences were observed. Interestingly, some differences between histological subtypes were observed, such as lower let-7 expression levels in acinar adenocarcinomas and mucinous BACs.
authors.affiliation: Department of Pathology, The Cancer Institute, Japanese Foundation for Cancer Research (JFCR), 3-10-6 Ariake, Koto-ku, Tokyo 135-8550, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Inamura
authors.forename: Yuki
authors.initials: Y
authors.lastname: Togashi
authors.forename: Kimie
authors.initials: K
authors.lastname: Nomura
authors.forename: Hironori
authors.initials: H
authors.lastname: Ninomiya
authors.forename: Miyako
authors.initials: M
authors.lastname: Hiramatsu
authors.forename: Yukitoshi
authors.initials: Y
authors.lastname: Satoh
authors.forename: Sakae
authors.initials: S
authors.lastname: Okumura
authors.forename: Ken
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ishikawa
mesh_terms: D002282:Adenocarcinoma, Bronchiolo-Alveolar / Q000235:genetics* / Q000473:pathology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000235:genetics / Q000473:pathology; D011379:Prognosis; D015996:Survival Rate
chemical_list: D035683:MicroRNAs; C487931:mirnlet7 microRNA, human