MicroRNA-31 controls G protein alpha-13 (GNA13) expression and cell invasion in breast cancer cells

Abstract

BackgroundGα13 (GNA13) is the α subunit of a heterotrimeric G protein that mediates signaling through specific G protein-coupled receptors (GPCRs). Our recent study showed that control of GNA13 expression by specific microRNAs (miRNAs or miRs) is important for prostate cancer cell invasion. However, little is known about the control of GNA13 expression in breast cancers. This project was carried out to determine (i) whether enhanced GNA13 expression is important for breast cancer cell invasion, and (ii) if so, the mechanism of deregulation of GNA13 expression in breast cancers.MethodsTo determine the probable miRNAs regulating GNA13, online miRNA target prediction tool Targetscan and Luciferase assays with GNA13-3′-UTR were used. Effect of miRNAs on GNA13 mRNA, protein and invasion was studied using RT-PCR, western blotting and in vitro Boyden chamber assay respectively. Cell proliferation was done using MTT assays.ResultsOverexpression of GNA13 in MCF-10a cells induced invasion, whereas knockdown of GNA13 expression in MDA-MB-231 cells inhibited invasion. Expression analysis of miRNAs predicted to bind the 3′-UTR of GNA13 revealed that miR-31 exhibited an inverse correlation to GNA13 protein expression in breast cancer cells. Ectopic expression of miR-31 in MDA-MB-231 cells significantly reduced GNA13 mRNA and protein levels, as well as GNA13-3′-UTR-reporter activity. Conversely, blocking miR-31 activity in MCF-10a cells induced GNA13 mRNA, protein and 3′-UTR reporter activity. Further, expression of miR-31 significantly inhibited MDA-MB-231 cell invasion, and this effect was partly rescued by ectopic expression of GNA13 in these cells. Examination of 48 human breast cancer tissues revealed that GNA13 mRNA levels were inversely correlated to miR-31 levels.ConclusionsThese data provide strong evidence that GNA13 expression in breast cancer cells is regulated by post-transcriptional mechanisms involving miR-31. Additionally our data shows that miR-31 regulates breast cancer cell invasion partially via targeting GNA13 expression in breast cancer cells. Loss of miR-31 expression and increased GNA13 expression could be used as biomarkers of breast cancer progression.Electronic supplementary materialThe online version of this article (doi:10.1186/s12943-015-0337-x) contains supplementary material, which is available to authorized users.

MicroRNAs regulate the epithelial–mesenchymal transition and influence breast cancer invasion and metastasis

“…Overexpression of miR-10b in breast cancer cells can inhibit the expression 25 Huang et al, 32 Bahena-Ocampo et al, 33 Liang et al, 34 Ma et al, 35 Petrovic, 36 Yan et al 37 51 Rasheed et al, 52 Tavazoie et al, 53 Chou et al, 54 Zhang et al 55 43 A study showed that the upregulation of miR-155 can facilitate tumor angiogenesis, while it is associated with a poor prognosis for triple-negative breast cancer patients. 44 Kong et al 45 reported that miR-155 can act on TGF-β/Smad4 signaling through RhoA, thereby promoting the EMT; in contrast, knockdown of miR-155 can significantly inhibit the TGF-β/Smad4-induced EMT.…”

“…In vitro experiments showed that miR-31 can inhibit the invasion and metastasis of breast cancer cells. 52 Moreover, miR-126, miR-206, and miR-335 can suppress breast cancer metastasis. 53 Chou et al 54 demonstrated that the transcription factor GATA3 can suppress breast cancer metastasis by upregulating miR-29b expression.…”

Is microRNA-31 a key regulator of breast tumorigenesis?

“…There is strong evidence that GNA13 (α subunit of a heterotrimeric G protein) expression is involved in breast tumorigenesis through enhancement of cell invasion, while partially regulated post-transcriptionally by miRNA-31 in breast cancer cell lines. Down-expression of miRNA-31 and hence increased GNA13 level leads to cancer progression (10). Based on previous findings provided by several studies miRNA-31 seems to be considered especially as a major regulator of metastasis formation in breast cancer patients as well as a crucial suppressor of mammary stem cells (MSC) neoplastic transformation.…”

High expression of GNA13 is associated with poor prognosis in hepatocellular carcinoma

“…These GPCRs can signal through heterotrimeric G proteins, especially the GNA12/GNA13 subfamily which has been shown to mediate cancer cell invasion and metastasis2223242526. It was reported that GAN13 had been closely associated with tumor progression in different types of human cancers, such as prostate, breast, colorectal, pancreatic and gastric cancers1617192027. These findings reveal a potential carcinogenic role of GNA13 in multiple human malignancies.…”

“…Recently, increased expression of GNA13 has been found in several types of malignancies, especially in more aggressive breast and prostate cancer. Furthermore, the impact of this upregulation could contribute to cancer cell invasion and migration1617. Li and the colleagues found GNA13 played a critical role in lysophosphatidic acid (LPA)-stimulated invasive migration of pancreatic cancer cells18.…”