miR-135b, upregulated in breast cancer, promotes cell growth and disrupts the cell cycle by regulating LATS2

Abstract

Dysregulation of microRNAs (miRNAs) plays a critical role in cancer progression. They can act as either oncogenes or tumor suppressor genes in human cancer. The purpose of this study was to investigate the crucial role of miR-135b in breast cancer and to validate whether miR-135b could regulate proliferation of breast cancer cells by effecting specific targets in the Hippo pathway. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was carried out to quantify the expression levels of miR-135b in both breast cancer tissues and cell lines. To characterize the function of miR-135b, MTT assays, colony formation assays, cell migration assays, cell invasion assays, and cell cycle assays were used. Luciferase reporter assays were performed to validate the regulation of a putative target of miR-135b, in corroboration with western blot assays. Finally, we verified the changes of cellular function after transfection of LATS2-siRNA. Our experiments indicate that expression of miR-135b was commonly upregulated in breast cancer specimens and breast cancer cells when compared with that in adjacent normal tissues and non-malignant breast epithelial cells. Enforced expression of miR-135b can regulate cellular proliferation, migration and invasion as well as disrupt the cell cycle of breast cancer cells. Luciferase assays revealed that miR-135b directly bound to the 3'-untranslated region (3'-UTR) of LATS2 (large tumor suppressor kinase 2), a critical gene in the Hippo pathway. Western blot analysis verified that miR-135b regulated the expression of LATS2 at protein levels. Further study demonstrated that the downstream gene of LATS2 in the Hippo pathway, such as cyclin-dependent kinase 2 (CDK2) and Phospho-Yes-associated protein (p-YAP), can also be regulated by miR-135b and LATS2 axis. Knockdown of endogenous LATS2 can mimic the result of miR-135b up-regulation in breast cancer. Taken together, our findings reveal that the miR-135b and LATS2 axis may be a potential therapeutic target for breast cancer in the future.

Dysregulation of microRNAs in triple-negative breast cancer

“…MiR-135b has been showed to be up-regulated in breast cancer [27], which is consistent with our study. Moreover miR-135b promotes cellular proliferation and disrupts the cell cycle of breast cancer cells by regulating LATS2 [27]. In our study we show a linear trend for T stage and expression of miR-135b-5p; we observe lower expression in higher tumor size.…”

“…Moreover, the miR-135b gene expression and its DNA methylation had a significant inverse correlation [26]. MiR-135b has been showed to be up-regulated in breast cancer [27], which is consistent with our study. Moreover miR-135b promotes cellular proliferation and disrupts the cell cycle of breast cancer cells by regulating LATS2 [27].…”

Exploring specific prognostic biomarkers in triple-negative breast cancer

“…Previously, miR-135b-5p has been well documented as a tumor suppressor [33][34][35] or oncogene [36][37][38] in breast cancer, but less is known about the expression and function of miR-135b-3p. In case that both 5p and 3p strands are functional and not degraded, despite targeting different mRNAs, they might cooperate temporally and result in a synergistic effect.…”

TGF-β1 promoted chondrocyte proliferation by regulating Sp1 through MSC-exosomes derived miR-135b

“…Bioinformatics analysis showed that miR-135b could target the 3ʹUTR of Sp1. MiR-135b, an oncogene, can regulate the development of various tumors [11][12][13]. Xu et al [14] found that miR-135b was expressed in MSCs and it was involved in the osteogenic differentiation of MSCs.…”