Investigating the mechanism by which SMAD3 induces PAX6 transcription to promote the development of non-small cell lung cancer

Baolan Li,Zhe Qian,Jie Li,Jiqing Hao,Aimin Hu,Hua Zheng,Wenyun Jia,Yuan Gao,Tongmei Zhang,Qiankun Zhang,Zan Liu,Ying Hu

doi:10.1186/s12931-018-0948-z

Baolan Li, Zhe Qian + Show 10 more

Open Access

https://doi.org/10.1186/s12931-018-0948-z

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Abstract

BackgroundThis study investigated the function of SMAD3 (SMAD family member 3) in regulating PAX6 (paired box 6) in non-small cell lung cancer.MethodsFirst, qRT-PCR was employed to detect SMAD3 expression in cancer tissues along with normal tissues and four cell lines, including BEAS-2B, H125, HCC827 and A549 cells. SMAD3 was knocked down by small interference RNA (siRNA), and then its expression was determined via qRT-PCR and Western blot analysis. The correlation between SMAD3 and PAX6 was determined by double luciferase reporter experiments and chromatin immunoprecipitation (ChIP) assay. Cell viability was evaluated by CCK-8 and colony forming assays, while cell migration and invasion were detected by Transwell analysis.ResultsSMAD3 and PAX6 were upregulated in lung cancer tissues and cancer cells. Knocking down SMAD3 and PAX6 by transfection with siRNAs specifically suppressed the expression of SMAD3 and PAX6 mRNA and protein levels. SMAD3 could promote PAX6 transcriptional activity by binding to its promoter. Reduced expression of SMAD3 led to the downregulation of PAX6 mRNA and protein levels along with decreased cell migration, invasion, proliferation and viability in A549 and HCC827 cells. PAX6 overexpression altered the si-SMAD3-induced inhibition of cell migration, invasion, proliferation and viability in A549 and HCC827 cells. Additionally, PAX6 knockdown alone also repressed the cell migration, invasion, proliferation and viability of the cell lines.ConclusionsSMAD3 promotes the progression of non-small cell lung cancer by upregulating PAX6 expression.

Highlights

This study investigated the function of SMAD3 (SMAD family member 3) in regulating PAX6 in non-small cell lung cancer
We investigated the function of SMAD3 in non-small cell lung cancer using cell proliferation and migration experiments and explored the relationship between SMAD3 and PAX6 with double luciferase reporter experiments and chromatin immunoprecipitation assay (ChIP)
Similar SMAD3 and PAX6 mRNA and protein expression was observed in the four cell lines, including the normal BEAS-2B human lung epithelial cells and H125, HCC827 and A549 cancer cell lines

Summary

Introduction

This study investigated the function of SMAD3 (SMAD family member 3) in regulating PAX6 (paired box 6) in non-small cell lung cancer. Li et al reported that the deregulation of SMAD3 expression was associated with ventricular septal defects [8]. Samanta et al reported that reducing SMAD3 expression could abrogate TGF-β-mediated growth inhibition, resulting in promoting tumorigenicity [9]. Previous studies have shown that SMAD3 is involved in aggressive tumor behavior in NSCLC and might act as a potential target for the treatment of the cancer [10]. A published paper reported that downregulating TGFBR2 expression promoted the proliferation, migration and invasion of NSCLC cells by reducing the activation and phosphorylation of Smad and Smad3 [11]. The elusive mechanisms involving SMAD3 in the development and progression of NSCLC deserve more attention

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