Studies have demonstrated low expression of miR-145 associated with cell proliferation and migration in a wide variety of tumors. Here, we studied the expression of miR-145 in relation to the occurrence and development of breast cancer. Total RNA from breast cancer tissue and corresponding adjacent normal tissue was extracted and used to detect miR-145 expression by quantitative real-time polymerase chain reaction (qRT-PCR). We also transfected breast cancer cells with hsa-miR-145 mimics, hsa-miR-145 inhibitor, mimics negative control (mimics NC) or inhibitor negative control (inhibitor NC). Cell proliferation was analyzed by colony formation assays and methyl thiazolyl tetrazolium assays. Cell proliferation in breast cancer cells was decreased after overexpression of miR-145 and increased following miR-145 suppression. Cell migration and invasion were assessed using Transwell and wound healing assays, respectively, and were also decreased after overexpression of miR-145 and increased after miR-145 suppression in breast cancer cells. Finally, western blot assays showed that overexpression of miR-145 inhibited expression of transforming growth factor-β1 (TGF-β1). Collectively, these data suggest that miR-145 may inhibit TGF-β1 protein expression which may in turn contribute to tumor formation.

The endoplasmic reticulum quality control (ERQC) system, including endoplasmic reticulum-associated degradation (ERAD), the unfolded protein response (UPR), and autophagy, presides over cellular protein secretion and maintains proteostasis in mammalian cells. As part of the immune system, a variety of proteins are synthesized and assembled correctly for the development, activation, and differentiation of immune cells, such as dendritic cells (DCs), macrophages, myeloid-derived-suppressor cells (MDSCs), B lymphocytes, T lymphocytes, and natural killer (NK) cells. In this review, we emphasize the role of the ERQC in these immune cells, and also discuss how the imbalance of ER homeostasis affects the immune response, thereby suggesting new therapeutic targets for immunotherapy.

Abstract. MicroRNA (miRNA) is a type of endogenous non-coding RNA implicated in various cellular processes. Studies have shown that miR-124 is involved in the malignant progression of cancer, but little is known concerning its potential role in breast cancer. Therefore, the purpose of this study was to conduct a functional analysis of miR-124 in breast cancer, and to identify its target genes in this disease. To this end, we used quantitative real-time PCR to examine the expression level of miR-124 in breast cancer tissue specimens and cell lines. To study the functional significance of miR-124, we overexpressed miR-124 with miR-124 mimics and observed breast cancer cell proliferation, colony formation, migration, and invasion abilities by in vitro cell culture experiments. Target prediction algorithms and luciferase reporter gene assays were used to identify the target genes of miR-124. We also knocked down miR-124 targets using short hairpin RNA (shRNA) constructs, and observed associated breast cancer cell characteristics by in vitro cell culture experiments. We found that miR-124 expression significantly decreased in breast cancer tissues and cells compared to normal tissues and cells. In addition, cell proliferation, colony formation, migration, and invasion were decreased after overexpression of miR-124 in breast cancer cells. Furthermore, we used several algorithms to identify the snail family zinc finger 2 (SNAI2) as a potential target gene of miR-124. The protein expression level and luciferase activity of the 3'-untranslated region of SNAI2 were significantly decreased in breast cancer cells transfected with miR-124 mimics. Cell proliferation, colony formation, migration, and invasion were also decreased after knockdown of SNAI2 by shRNA. In conclusion, our data suggest that miR-124 expression is decreased in breast cancer and plays an important role as a tumor suppressor gene by targeting SNAI2. These findings may reveal novel perspectives for clinical treatments against breast cancer.

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Cigarette smoking is a well-known risk factor in the development and progression of malignant diseases. Nicotine, the major constituent in cigarette smoke, has also shown negative effects on stem cells. Mesenchymal stem cells (MSCs) have been widely demonstrated to migrate into tumors and play key roles in cancer progression. However, the mechanisms by which nicotine impacts MSCs and tumorigenesis of lung cancer are still undetermined. In this study we investigated the effects of nicotine on human umbilical cord mesenchymal stem cells (hUC-MSCs) and the impacts of nicotine-treated hUC-MSCs on tumor formation and progression. We found that nicotine has a toxic effect on hUC-MSCs and changes the morphology, inhibits proliferation and promotes apoptosis of hUC-MSCs in a dose-dependent manner. Nicotine-treated hUC-MSCs produce higher level of IL-6. Moreover, nicotine promotes migration, stemness and epithelial-mesenchymal transition (EMT) of hUC-MSCs by inhibiting E-cadherin expression and upregulating mesenchymal markers such as N-cadherin and Vimentin, leading to the induction of stem cell markers Sox2, Nanog, Sall4, Oct4 and CD44. Migration and proliferation of non-small cell lung cancer A549 cells and breast cancer MCF-7 cells are promoted after their coculture with nicotine-treated hUC-MSCs in a cell-cell contact-independent manner. Furthermore, nicotine-treated hUC-MSCs promote tumor formation and growth of A549 cells in nude mice. These studies demonstrated that the enhanced stemness and EMT of hUC-MSCs induced by nicotine are critical for the development of tobacco-related cancers.