Downregulation of cytokeratin 18 enhances BCRP-mediated multidrug resistance through induction of epithelial-mesenchymal transition and predicts poor prognosis in breast cancer.

Multiple drug resistance (MDR) and metastasis have been identified as the two major causes of the poor prognosis of patients with breast cancer. However, the relationship between MDR and metastasis has not been characterized. Epithelial­mesenchymal transition (EMT), a process known to promote metastasis in cancer, has been shown to be associated with the MDR phenotype of many tumor types. Reduced cytokeratin 18 (CK18) expression is thought to be one of the hallmarks of EMT, and the role of CK18 in MDR of metastatic breast cancer remains unknown. In the present study, we revealed that the expression of CK18 was significantly downregulated in breast cancer tissues and in an MDR cell line overexpressing breast cancer resistant protein (BCRP), and the presence of low levels of CK18 was associated with TNM stage, lymph node metastasis, and unfavorable survival in breast cancer patients. Further results demonstrated that CK18 stable knockdown using shRNA increased BCRP expression and induced the EMT process in human breast cancer MCF­7 cells. Moreover, CK18 knockdown was associated with the activation of the NF­κB/Snail signaling pathway, which has been revealed to regulate EMT and BCRP. Based on these findings, we concluded that CK18 knockdown enhanced BCRP­mediated MDR in MCF­7 cells through EMT induction partly via the NF­κB/Snail pathway. These findings provide a valuable insight into the potential role of CK18 in MDR, migration and invasion of breast cancer cells. Reduced expression of CK18 may be a novel biomarker for predicting the poor prognosis of breast cancer patients.

Baicalein attenuates monocrotaline-induced pulmonary arterial hypertension by inhibiting endothelial-to-mesenchymal transition.

AIMS: Endothelial-to-mesenchymal transition (EndoMT) was shown to lead to endothelial cell (EC) dysfunction in pulmonary arterial hypertension (PAH). Baicalein was reported to inhibit epithelial-to-mesenchymal transition (EMT), a biological process that has many regulatory pathways in common with EndoMT. Whether it can attenuate PAH by inhibiting EndoMT remains obscure. MAIN METHODS: PAH was induced by a single subcutaneous injection of MCT (60 mg/kg) in male Sprague Dawley rats. Two weeks after MCT administration, the rats in the treatment groups received baicalein orally (50 or 100 mg/kg/day) for an additional 2 weeks. Hemodynamic changes and right ventricular hypertrophy (RVH) were evaluated on day 28. Cardiopulmonary interstitial fibrosis was detected using Masson's trichrome, Picrosirius-red, and immunohistochemical staining. The reactivity of pulmonary arteries (PAs) was examined ex vivo. The protein expresson of EndoMT molecules, bone morphogenetic protein receptor 2 (BMPR2), and nuclear factor-κB (NF-κB) was examined to explore the mechanism of protective action of baicalein. KEY FINDINGS: Baicalein (50 and 100 mg/kg) significantly alleviated MCT-induced PAH and cardiopulmonary interstitial fibrosis. Furthermore, baicalein treatment enhanced PA responsiveness to acetylcholine (ACh) in PAH rats. The upregulation of EndoMT molecules (N-cadherin, vimentin, Snail, and Slug) strongly suggest that EndoMT participates in MCT-induced PAH, which was reversed by baicalein (50 and 100 mg/kg) treatment. Moreover, baicalein partially reversed MCT-induced reductions in BMPR2 and NF-κB activation in the PAs. SIGNIFICANCE: Baicalein attenuated MCT-induced PAH in rats by inhibiting EndoMT partially via the NF-κB-BMPR2 pathway. Thus, baicalein might be considered as a promising treatment option for PAH.

Baicalein attenuates monocrotaline-induced pulmonary arterial hypertension by inhibiting vascular remodeling in rats.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a devastating cardiopulmonary disorder characterized by elevated pulmonary arterial pressure (PAP) and right ventricular hypertrophy (RVH) driven by progressive vascular remodeling. Reversing adverse vascular remodeling is an important concept in the treatment of PAH. Endothelial injury, inflammation, and oxidative stress are three main contributors to pulmonary vascular remodeling. Baicalein is a natural flavonoid that has been shown to possess anti-proliferative, anti-inflammatory, anti-oxidative, and cardioprotective properties. We hypothesized that baicalein may prevent the progression of PAH and preserve the right heart function by inhibiting pulmonary arterial remodeling. METHODS: Male Sprague-Dawley rats were distributed randomly into 4 groups: control, monocrotaline (MCT)-exposed, and MCT-exposed plus baicalein treated rats (50 and 100 mg/kg/day for 2 weeks). Hemodynamic changes, RVH, and lung morphological features were examined on day 28. Apoptosis was determined by TUNEL staining, and the mRNA levels of tumor necrosis factor alpha (TNF-α), interleukin-1ß (IL-1ß), and IL-6 were detected by qRT-PCR. The changes in oxidative indicators, including malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were measured using corresponding commercial kits. The levels of Bax, Bcl-2, and cleaved caspase-3, and the activation of mitogen-activated protein kinase (MAPK) and NF-κB were assessed by western blotting. RESULTS: MCT induced an increase in hemodynamic parameters and RVH, which were attenuated by baicalein treatment. Baicalein also blocked MCT-induced pulmonary arterial remodeling. The levels of apoptotic (Bax/Bcl-2 ratio and cleaved caspase-3) and inflammatory (IL-6, TNF-α, and IL-1ß) biomarkers in lung tissue were lower in baicalein-treated groups. Baicalein also decreased MDA level, and increased SOD and GSH-Px activity in rat pulmonary tissue. Furthermore, baicalein inhibited MCT-induced activation of the MAPK and NF-κB pathways. CONCLUSION: Baicalein ameliorates MCT-induced PAH by inhibiting pulmonary arterial remodeling at least partially via the MAPK and NF-κB pathways in rats.