miR-99a reveals two novel oncogenic proteins E2F2 and EMR2 and represses stemness in lung cancer

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Lung cancer is a highly aggressive malignancy with poor prognosis.
• MicroRNA dysregulation is implicated in tumor growth, progression, and metastasis.
• Identifying specific microRNAs and their targets is crucial for understanding lung tumorigenesis.

Purpose of the Study:

• To investigate the role of microRNA-99a (miR-99a) in lung cancer.
• To identify novel targets of miR-99a involved in lung tumor progression.
• To evaluate the therapeutic potential of miR-99a in preclinical models.

Main Methods:

• Analysis of microRNA expression in 47 lung cancer biopsies.
• In vitro studies using lung cancer cell lines (H1650, H1975, H1299) to assess miR-99a effects.
• Identification of miR-99a targets using 3'-UTR binding assays.
• In vivo studies in mice using H1975-derived tumors.
• Protein expression analysis of E2F2 and EMR2 in 119 lung cancer biopsies.

Main Results:

• miR-99a expression was downregulated in lung cancer and inhibited cell proliferation, induced cell cycle arrest, and apoptosis in vitro.
• miR-99a directly targets and downregulates E2F2 (E2F transcription factor 2) and EMR2 (EGF-like module-containing, mucin-like, hormone receptor-like 2).
• miR-99a suppressed epithelial-to-mesenchymal transition (EMT) and cancer stem cell (CSC) populations in vitro and in vivo.
• E2F2 and EMR2 were upregulated in lung adenocarcinoma and correlated with EMT markers (vimentin, β-catenin).
• miR-99a expression inversely correlated with E2F2 and directly with β-catenin in patient biopsies.

Conclusions:

• miR-99a identifies E2F2 and EMR2 as novel targets crucial for lung tumorigenesis.
• Inhibition of E2F2 and EMR2 by miR-99a represses EMT, stemness, and CSC population in lung cancer.
• miR-99a holds potential as a therapeutic agent for lung cancer by targeting key oncogenic pathways.