let-7b and miR-126 Are Down-Regulated in Tumor Tissue and Correlate with Microvessel Density and Survival Outcomes in Non–Small–Cell Lung Cancer

Abstract

Angiogenesis is a critical event in the development, progression, and spread of various human cancers, including lung cancer. Molecular mechanisms that underlie the complex regulation of angiogenic processes are poorly understood. However, an increasing body of evidence indicates miRNAs as important regulators of tumor angiogenesis. Forceps biopsies were collected from tumor tissue, surrounding tissue, and non-tumor tissue from 50 NSCLC patients. Lung tissue samples from individuals with no clinical evidence of a cancerous disease served as controls. Immunohistochemical staining for Factor VIII was used to evaluate microvessel density (MVD). TaqMan® primer-probe sets were used in quantitative real-time RT-PCR reactions to determine expression levels of let-7b, miR-126, miR-9, and miR-19a. We demonstrated significantly higher MVD and decreased expression levels of let-7b and miR-126 in tumor tissue and surrounding tissue in comparison to corresponding non-tumor tissue or lung tissue from the control group. In addition, no differences in MVD and expression levels of both miRNAs between tumor tissue and surrounding tissue from NSCLC patients were observed. Low expression of both miRNAs correlated with high MVD and worse progression-free survival and overall survival. These observations strongly suggest similar molecular alternations within tumor tissue and surrounding tissue that comprise a specific microenvironment. Low expression of let-7b and miR-126 seems to have a possible anti-angiogenic role in lung tumor tissue and significantly correlates with worse survival outcomes for lung cancer patients. Moreover, the regulation of let-7b and miR-126 expression could have therapeutic potential because it could reduce tumor angiogenesis and therefore suppress tumor growth in lung cancer patients.

Let-7a is differentially expressed in bronchial biopsies of patients with severe asthma

“…Quantitative PCR was used to analyze the expression of selected miRNAs as previously described 45 . Isolated RNA was reverse transcribed using miRNA-specific RT primers (RNU6B, hsa-let-7a, hsa-miR-21, and hsa-miR-223) and a TaqManH MicroRNA Reverse Transcription Kit (Applied Biosystems, Foster City, California, USA).…”

Reproducible combinatorial regulatory networks elucidate novel oncogenic microRNAs in non-small cell lung cancer

“…Moreover, TGFBR2 was reported as a direct target of miR-17-5p (Dews et al 2010). So far, the expression pattern for miR-9-5p in lung tumor versus non-tumor samples has been inconsistently reported: up-regulation (Crawford et al 2009;Kang et al 2013;Xu et al 2014), downregulation (Yanaihara et al 2006), or insignificant change in expression (Jusufovic et al 2012). To the best of our knowledge, there is no report on miR-130b-3p expression in NSCLC.…”

The regulatory role of microRNAs in angiogenesis‐related diseases

“…Meng et al52 also found that miR‐126 promotes the proliferation and/or migration of EPCs and enhances angiogenesis, thereby promoting thrombus organization and recanalization in rat inferior vena cava thrombosis model. In contrast, the down‐regulation of miR‐126 enhances VEGFA activity in lung cancer, oral cancer and breast cancer,53, 54, 55, 56 and the restoration of miR‐126 decreases VEGF and tumour size in lung cancer 53, 57. In addition, miR‐126 inhibits gastric cancer angiogenesis by significantly reducing VEGFA expression and the activation of its downstream genes, Akt/protein kinase B, mTOR and Erk1/2 in the gastric cancer cell lines SGC‐7901, MKN‐28 and MKN‐45 27, 58.…”