Abstract
BackgroundBladder cancer is the most common malignancy in urinary system and the ninth most common malignancy in the world. MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression by targeted repression of transcription and translation and play essential roles during cancer development. We investigated the expression of miR-135a in bladder cancer and explored its bio-function during bladder cancer progression.MethodsThe expression of miR-135a in bladder cancer cells and tissues are performed by using Real-time PCR assay. Cell viability assay (MTT assay), colony formation assay, anchorage-independent growth ability assay and Bromodeoxyuridine labeling and immunofluorescence (BrdUrd) assay are used to examine cell proliferative capacity and tumorigenicity. Flow cytometry analysis is used to determine cell cycle progression. The expressions of p21, p27, CyclinD1, Ki67, PHLPP2 and FOXO1 are measured by Western blotting assay. Luciferase assay is used to confirm whether FOXO1 is the direct target of miR-135a.ResultsmiR-135a is upregulated in bladder cancer cells and tissues. Enforced expression of miR-135a promotes bladder cancer cells proliferation, whereas inhibition of miR-135a reverses the function. Furthermore, for the first time we demonstrated PHLPP2 and FOXO1 are direct targets of miR-135a and transcriptionally down-regulated by miR-135a. Suppression of PHLPP2 or FOXO1 by miR-135a, consisted with dysregulation of p21, p27, Cyclin D1 and Ki67, play important roles in bladder cancer progression.ConclusionOur study demonstrates that miR-135a promotes cell proliferation in bladder cancer by targeting PHLPP2 and FOXO1, and is performed as an onco-miR.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-015-0438-8) contains supplementary material, which is available to authorized users.
Highlights
Bladder cancer is the most common malignancy involving the urinary system and more than 350,000 new cases of bladder cancer are diagnosed globally each year [1,2]
The results showed that the relative expression of miR-135a in bladder cancer tissues was significantly higher than that of their matched adjacent normal tissues (n = 7, r = 0.896, P = 0.006; Figure 1B)
Colony formation assays showed that overexpression of miR-135a enhanced the proliferation of bladder cancer cells, and colonies were much larger in bladder cancer cells stably overexpressing miR-135a (Figure 2B, Additional file 1: Figure S1B and Additional file 2: Figure S2A)
Summary
Bladder cancer is the most common malignancy involving the urinary system and more than 350,000 new cases of bladder cancer are diagnosed globally each year [1,2]. Bladder cancer is the fourth most common cancer in males and ninth most common in females; it is the ninth most common malignancy overall [2,3]. The PHLPP (Pleckstrin Homology (PH) domain leucinerich repeat protein phosphatase) isoforms comprises three members, PHLPP1α, PHLPP1β, and PHLPP2, which are essential regulators of Akt serine-threonine kinases [5,6,7]. Bladder cancer is the most common malignancy in urinary system and the ninth most common malignancy in the world. MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression by targeted repression of transcription and translation and play essential roles during cancer development. We investigated the expression of miR-135a in bladder cancer and explored its bio-function during bladder cancer progression
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