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Resistance to breast cancer (BCa) chemotherapy severely hampers the patient's prognosis. MicroRNAs provide a potential therapeutic prospect for BCa. In this study, the reversal function of microRNA34a (miR34a) on doxorubicin (Dox) resistance of BCa and the possible mechanism was investigated. We found that the relative level of miR34a was significantly decreased in Dox-resistant breast cancer cell MCF-7 (MCF-7/A) compared with Dox-sensitive MCF-7 cells. Transfection with miR34a significantly suppressed the invasion, migration, adhesion of MCF-7/A cells without inhibiting their growth obviously. The combination of miR34a and Dox could significantly inhibit the proliferation, migration, invasion and induce the apoptosis of MCF-7/A cells. The synergistic effect of this combination on resistant MCF-7/A cells has no obvious relation with the expressions of classical drug-resistant proteins P-GP, MRP and GST-
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【Objective】 To investigate the regulatory effect of annexin A5 on glioma cell invasion and migration and its mechanism. 【Methods】 The expression of annexin A5 in 100 cases of glioma tissues and 20 cases of normal brain tissues was detected by immunohistochemistry. The expression of annexin A5 was downregulated by transfection with siRNA targeting annexin A5 (si-Annexin A5) in human glioma cell line (U251). The expression of annexin A5 was confirmed by RT-PCR and Western blot analysis. The proliferation ability of U251 cells was detected by MTT test and colony formation test, the apoptosis of U251 cells was detected by flow cytometry and Hoechst 33258 staining, and the migration and invasion ability of U251 cells was examined by wound healing test and Matrigel Transwell invasion test. The expressions of Raf, p-Raf, MEK1/2, p-MEK1/2, ERK1/2, p-ERK1/2, c-Myc and E-Cadherin in U251 cells were analyzed by Western blot. 【Results】 Compared with those of normal brain tissues, the mRNA and protein expression levels of Annexin A5 in glioma tissues increased by 2.45 times and 2.87 times, respectively (P<0.05). Pearson correlation analysis showed that with the increase of tumor grade, the positive rate of Annexin A5 gradually increased, and the tumor grade and positive rate were significantly positively correlated (r=1.000, P=0.000). The cell viability of U251 cells in the si-Annexin A5 group after 48 h and 72 h of culture was significantly reduced by 29.46% and 40.43%, respectively, compared with that in the control group (P<0.05). Compared with the control group, in the si-Annexin A5 group the colony formation rate was reduced by 68.58%, while the apoptosis rate was increased by 24.41 times (P<0.05); the cell migration rate and invasion rate were reduced by 65.35% and 68.80% (P<0.05). The protein expression of p-Raf, p-MEK1/2, p-ERK1/2 and c-Myc in the si-Annexin A5 group were significantly reduced by 54.67%, 70.37%, 60.26% and 54.95%, respectively, and that of E-Cadherin was increased by 3.58 times (P<0.05). 【Conclusion】 Downregulation of Annexin A5 inhibits the growth and motility of glioma cells and induces cell apoptosis by inhibiting the Raf/MEK/ERK signaling pathway.
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This study aimed to explore the anti-tumor activity and mechanisms of action of isorhamnetin, a compound isolated from Astragalus membranaceus, in combination with sorafenib for treatment of renal cell carcinoma (RCC). The anti-tumor activity of isorhamnetin in combination with sorafenib was detected by MTT assay with cells in culture or Renca xenograft model in mice. Western blot was used to study the mechanisms of isorhamnetin in combination with sorafenib. Lymphocyte proliferation assay was also used to investigate the effects of the two drugs in combination. The results indicated that isorhamnetin inhibited the proliferation of RCC cells, with IC50 for A498, 786-O and Renca cell lines with being 31.7, 28.8 and 106.0 μmol·L-1, respectively. Isorhamnetin in combination with sorafenib improved the anti-lymphocyte proliferation activity of sorafenib with the IC50 down to 12.0 μmol·L-1. Isorhamnetin inhibited the growth of RCC in mice slightly with the inhibition efficiency at 26.9%. With 50.0 mg·kg-1 isorhamnetin in combination with 20.0 mg·kg-1 sorafenib, the anti-tumor activity of sorafenib was enhanced, with inhibition of growth rate increased to 60.7%. Meanwhile, isorhamnetin in combination with sorafenib could promote the lymphocytes proliferation in Renca xenograft model. Western blot results showed that combination of isorhamnetin and sorafenib could inhibit c-Raf/MEK/ERK and AKT/mTOR signaling pathways. In conclusion, the combination of isorhamnetin with sorafenib could increase the anti-tumor activity of sorafenib in RCC in vitro and in vivo. The mechanisms may be related to the inhibition of c-Raf/MEK/ERK and AKT/mTOR signaling pathways. Procedures for animal study were performed with approval of the Animal Care and Use Committee of the Chinese Academy of Medical Sciences and Peking Union Medical College.
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Objective: To explore the mechanism of the intervention of Xinkeshu Tablets (XKST) on atherosclerosis (AS) and provide reference for the secondary development and clinical application of XKST. Methods: The integrated pharmacology platform was used to predict the key targets and pathways of the intervention of XKST on AS and its molecular mechanism was also explored. Results: In the integrative analysis of heterogeneous network of “TCM-component-target-pathway”, 80 relevant effective ingredients were found, including B4GALT4, B4GALT2, PRKCD, GCK, GNB1, and other key targets; Endocrine system, thyroid hormone signaling pathway, nervous system, estrogen signaling pathway, and chemokine signaling pathway were key pathways related with its anti-atherosclerosis. Conclusion: According to the analysis and prediction of the enrichment information, the effect of XKST on common regulating PI3K/Akt/eNOS and Raf/MEK/ERK signaling pathway and protecting vascular endothelial cells is first prompted, thus achieving the intervention in AS.
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Aim To study the inhibitory effect of isoquercitrin on Raf/MEK/ERK signaling pathway in HepG2 cells.Methods MTT was used to detect the proliferation of human liver cancer HepG2 cells after the treatment of isoquercitrin.The morphology and growth of cells were observed under inverted microscope after the different concentrations of isoquercitrin(0, 40, 80, 160, 320 μmol·L-1) to treat HepG2 cells for 24 and 48 h.Cell cycle was assessed by flow cytometry.Ras, Raf, MEK, ERK expression was assayed by Western blot, and mRNA expression was detected by quantitative fluorescence PCR.Results Isoquercitrin could inhibit the growth of HepG2 cells in a concentration-and time-dependent manner.Typical morphological changes of apoptosis were observed by inverted microscopy after HepG2 cells were treated with different concentrations of of isoquercitrin for 24 h or 48 h.The cell cycle assay showed that with the increasing concentration of isoquerditrin, the number of cells that was arrested in G1 phase gradually increased.Compared with the blank group, the expressions of Ras, Raf, MEK, ERK mRNA were down-regulated, and related proteins expression were also down-regulated(P<0.05), and these results had statistical significance.Conclusion Isoquercitrin can induce the apoptosis of HepG2 cells, which may be related to the Raf/MEK/ERK signaling pathway.
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@#Autophagy is a conserved self-defense mechanism of organism, degrading the necrotic organelles and excess protein into small molecules for recycling. Autophagy plays a role in both physiological and pathological condition, influencing the expression of intracellular substance through multiple signaling pathways. Although it has been demonstrated that Ras/Raf/MEK/ERK signaling pathway was not only extensively involved in the regulation of cell growth, proliferation, differentiation and apoptosis, but was also implicated in autophagy and autophagic cell death, though its detailed mechanisms involved in regulation of autophagy has not been fully elucidated yet. This review focused on the advances of autophagy induced by Ras/Raf/MEK/ERK signaling pathway, to better understand the role of Ras/Raf/MEK/ERK signaling pathway in regulation of autophagy.
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Advances in the understanding of cancer at the molecular level have led to much progress in the development of anti-cancer agents. Among the newly invented medications for targeted cancer therapy, protein kinase inhibitors target intracellular molecules crucial in signaling pathways for cancer cell survival, proliferation, and disease progression. The Raf serine/threonine kinases are pivotal molecules within the Raf/mitogen extracellular kinase (MEK)/extracellular signal-related kinase (ERK) signaling pathway. The exact function of Raf in normal human cells is not yet understood; however, preclinical and clinical researches have shown that over expression of Raf gene or overreaction of Raf kinase isoforms have critical roles in many types of solid tumors, including renal cell carcinoma, hepatocellular carcinoma, melanoma, and non-small cell lung cancer (NSCLC). Sorafenib is the first oral, multi-kinase inhibitor that targets the Raf kinases. It also has a broad spectrum activity against other receptor tyrosine kinases associated with vascular endothelial growth factor receptors and platelet-derived growth factor receptors. Sorafenib was recently approved by FDA for use in advanced renal cell cancer, and is currently undergoing active investigation in the treatment of other types of malignancies, such as melanoma, liver cancer, prostate cancer, and NSCLC. In this review, we will illustrate the role of Raf in both normal and malignant cells, the mechanism of sorafenib in the treatment of renal cell carcinoma, as well as clinical data that support its use and further investigation in advanced renal cell carcinoma, melanoma, and other tumor types.