RESUMO
Chikusetsusaponin IVa (CsIVa) is a natural active monomer of triterpene saponins in the Chinese herbal medicine of Panax japonicus, which has anti-inflammatory, anti-tumor and other effects. However, its function and mechanism in triple negative breast cancer (TNBC) remain unclear. This study investigated the inhibitory effect and mechanisms of CsIVa on the proliferation of triple negative breast cancer cell line MDA-MB-231. In this study, we found that CsIVa could significantly inhibit the proliferation of MDA-MB-231 cells and eliminate its potential toxic effect on normal breast cells (MCF-10A). The transcriptome sequencing results showed that the inhibition of proliferation of MDA-MB-231 cells by CsIVa was closely related to cell cycle and the pathway regulating cell cycle. Further studies confirmed that CsIVa blocked the cell cycle in G2/M phase by down-regulating the expression of cyclin dependent kinase 1 (CDK1), cyclin B1 and up-regulating the expression of cyclin dependent kinase inhibitor 1A (p21). Moreover, CsIVa can block cell cycle through inhibiting PI3K/AKT signal pathway. In conclusion, CsIVa regulates the expression of cell cycle related proteins (p21, CDK1, cyclin B1) via inhibiting the activity of PI3K/AKT signaling pathway, blocks TNBC cell cycle, and thus exerts its anti-tumor activity.
RESUMO
OBJECTIVE@#To test the hypothesis that the inhibition of endoplasmic reticulum (ER) stress-induced apoptosis in oxidized low-density lipoproteins (ox-LDL)-induced human aortic-vascular smooth muscle cells (HA-VSMCs) was associated with suppression of the protein kinase RNA-like ER kinase (PERK)-eukaryotic translation initiation factor 2α (eIF2α)-activating transcription factor 4 (ATF4)-CCAAT/enhancer binding protein homologous protein (CHOP) signaling pathway by Pollen Typhae total flavone (PTF).@*METHODS@#Primary HA-VSMCs were cultured and identified. The cultured HA-VSMCs were randomized into 5 groups, including a normal control group, an ox-LDL group (70 μg/mL high ox-LDL), an HPTF group (70 μg/mL high ox-LDL+500 μg/mL PTF), an MPTF group (70 μg/mL high ox-LDL+250 μg/mL PTF), and a LPTF group (70 μg/mL high ox-LDL+100 μg/mL PTF) in the first part; and a normal control group, an ox-LDL group (70 μg/mL high ox-LDL), an MPTF group (70 μg/mL high ox-LDL+250 μg/mL PTF), a shRNA group (transducted with PERK shRNA lentiviral particles), a scramble shRNA group (transducted with control shRNA lentiviral particles), an MPTF+ox-LDL+shRNA group (250 μg/mL PTF+70 μg/mL high ox-LDL+PERK shRNA lentiviral particles) and an ox-LDL+shRNA group (70 μg/mL high ox-LDL+PERK shRNA lentiviral particles) in the second part. The protein expression levels of ER-associated apoptosis proteins were detected by Western blot, and their mRNA expression levels were detected by quantitative real-time reverse transcription-polymerase chain reaction. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was applied to test cell viability, and the level of apoptosis was monitored by flow cytometry.@*RESULTS@#The MTT assay and flow cytometry showed that the ox-LDL group had a significant increase in apoptosis, which was attenuated in PTF treatment groups and shRNA groups. Moreover, the ox-LDL group had increased protein and mRNA levels of binding immunoglobulin protein and ER-associated apoptosis proteins, such as PERK, eIF2α, ATF4 and CHOP, which were attenuated in PTF treatment groups and shRNA groups.@*CONCLUSIONS@#The apoptosis induced by ox-LDL had a strong relation to ER stress. The protective effect of PTF on ER stressinduced apoptosis was associated with inhibition of the PERK-eIF2α-ATF4-CHOP pathway, which might be a potential therapeutic strategy for enhancing the stability of atherosclerotic plaques.