Cannabinoid receptors promote chronic intermittent hypoxia-induced breast cancer metastasis via IGF-1R/AKT/GSK-3ß.

The progression of breast cancer is closely related to obstructive sleep apnea-hypopnea syndrome (OSAHS). Low concentrations of cannabinoids promote tumor proliferation. However, the role of cannabinoid receptors (CBs) in chronic intermittent hypoxia (CIH)-induced breast cancer has not been reported. The migration and invasion of breast cancer cell lines (MCF-7 and T47D) were measured by scratch assay and transwell assay. Gene and protein expressions were analyzed by qPCR and western blotting. Tumor xenograft mice model were established to evaluate the function of CBs. We observed that chronic hypoxia (CH) and CIH increased CBs expression and promoted migration and invasion in breast cancer. Mice grafted with MCF-7 exhibited obvious tumor growth, angiogenesis, and lung metastasis in CIH compared with CH and control. In addition, CIH induced CBs expression, which subsequently activated insulin-like growth factor-1 receptor (IGF-1R)/AKT/glycogen synthase kinase-3ß (GSK-3ß) axis. Knockdown of CBs alleviated CIH-induced migration and invasion of breast cancer in vitro. Furthermore, CIH exaggerated the malignancy of breast cancer and silencing of CBs suppressed tumor growth and metastasis in vivo. Our study contributed to understanding the role of CIH in breast cancer development modulation.

Obstructive sleep apnea syndrome and causal relationship with female breast cancer: a mendelian randomization study.

Although observational studies have reported a positive association between obstructive sleep apnea syndrome (OSAS) and breast cancer (BC) risk, causality remains inconclusive. We aim to explore whether OSAS is associated with etiology of BC by conducting a two-sample Mendelian randomization (MR) study in a Chinese population and Asian population from the Breast Cancer Association Consortium (BCAC). We found a detrimental causal effect of OSAS on BC risk in the primary analysis of our samples (IVW OR, 2.47 for BC risk per log-odds increment in OSAS risk, 95% CI = 1.86-3.27; P = 3.6×10-10). This was very similar to results of the direct observational case-control study between OSAS and BC risk (OR = 2.80; 95% CI = 2.24-3.50; P =1.4×10-19). Replication in the Asian population of the BCAC study also supported our results (IVW OR, 1.33 for BC risk per log-odds increment in OSAS risk, 95% CI = 1.13-1.56; P = 0.0006). Sensitivity analyses confirmed the robustness of our findings. We provide novel evidence that genetically determined higher risk of OSAS has a causal effect on higher risk of BC. Further studies focused on the mechanisms of the relationship between OSAS and breast carcinogenesis are needed.

Toll-Like Receptor 4 (TLR-4) Pathway Promotes Pulmonary Inflammation in Chronic Intermittent Hypoxia-Induced Obstructive Sleep Apnea.

BACKGROUND Studies have shown that intermittent hypoxia mimics obstructive sleep apnea in causing pulmonary inflammation, but the mechanism is not yet clear.TLR-4 is a recognized proinflammatory factor, so the purpose of this study was to assess the function of TLR-4 in pulmonary inflammation induced by chronic intermittent hypoxia simulating obstructive sleep apnea. MATERIAL AND METHODS Healthy male Wistar rats were divided into 3 groups (8 in each group): the normoxia control group (CG), the intermittent hypoxia group (IH), and the TLR4 antagonist TAK242 treatment group (3 mg/kg, daily), with exposure durations of 12 weeks and 16 weeks (HI). The morphological changes of lung tissue were determined with hematoxylin-eosin (HE) staining. The expressions of the TLR-4 pathway in lung tissue were tested by Western blotting and RT-PCR. The levels of IL-6 and TNF-a in serum and lung tissue were detected by enzyme-linked immunosorbent assay (ELISA). The levels of SOD and MDA in lung tissue were detected by use of SOD and MDA kits, respectively. RESULTS After TAK242 treatment, damage to lung tissue was increased, and the expressions of TLR-4, MYD88, P65, IL-6, TNF-α, MDA, and SOD were decreased. Intermittent hypoxic exposure caused alveolar expansion, thickening of alveolar septum, and fusion of adjacent alveoli into larger cysts under intermittent hypoxia in a time-dependent manner. Compared with the CG and HI groups, the mean lining interval (MLI) become more thickened and the alveolar destruction index (DI) increased significantly in the IH group. CONCLUSIONS Chronic intermittent hypoxia causes pulmonary inflammatory response and the inflammatory pathway involved in TLR4 receptor may be one of the mechanisms that trigger lung inflammation.

Effects of RNA interference-mediated silencing of toll-like receptor 4 gene on proliferation and apoptosis of human breast cancer MCF-7 and MDA-MB-231 cells: An in vitro study.

Breast cancer is known as the most prevalent cancer in women worldwide, and has an undeniable negative impact on public health, both physically, and mentally. This study aims to investigate the effects of toll-like receptor 4 (TLR4) gene silencing on proliferation and apoptosis of human breast cancer cells to explore for a new theoretical basis for its treatment. TLR4 small interference RNA (siRNA) fragment recombinant plasmids were constructed, including TLR4 siRNA-1, TLR4 siRNA-2, and TLR4 siRNA-3. Human breast cancer MCF-7 and MDA-MB-231 cells were assigned into blank, negative control (NC), TLR4 siRNA-1, TLR4 siRNA-2, and TLR4 siRNA-3 groups. MCF-7 and MDA-MB-231 cell growth was detected by MTT assay. Apoptosis and cell cycle were determined by flow cytometry. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis were conducted to determine the expression of TLR4, CDK4, cyclin D1, Livin, Bcl-2, p53, c-FLIP, and caspase-3. In comparison with the NC and blank groups, the TLR4 siRNA-1, TLR4 siRNA-2, and TLR4 siRNA-3 groups showed decreased the expression of TLR4, inhibited proliferation of MCF-7 and MDA-MB-231 cells and promoted MCF-7 and MDA-MB-231 cell apoptosis, and the cells were blocked in G1 phase. In comparison with the NC and blank groups, in the TLR4 siRNA-1, TLR4 siRNA-2, and TLR4 siRNA-3 groups, siRNA-TLR4 significantly increased expression of p53 and caspase-3 in MCF-7 and MDA-MB-231 cells, while it decreased the expressions of CDK4, cyclinD1, Livin, Bal-2, and c-FLIP. The study demonstrates that TLR4 gene silencing inhibits proliferation and induces apoptosis of MCF-7 and MDA-MB-231 cells.