Gallic acid (GA) possesses potential antitumoral activity on different types of malignancies. In this study, we aimed to explore the antitumoral effects of GA on triple-negative breast cancer (TNBC) cells, the breast cancer cells showing resistance to hormonal therapy or HER2 receptor targeting therapy. We observed that GA treatment significantly decreased the cell viability of human TNBC cell line MDA-MB-231 and HS578T in a dose-dependent manner. In addition, GA exerted a relative lower cytotoxicity on noncancer breast fibroblast MCF-10F. Next, we analyzed the changes of cell-cycle distribution in response to GA treatment and found that GA led to an increase of G0/G1 and sub-G1 phase ratio in MDA-MB-231 cells. We further explored the crucial mediators controlling cell cycle and inducing apoptotic signaling, and the findings showed that GA downregulated cyclin D1/CDK4 and cyclin E/CDK2, upregulated p21and p27, and induced activation of caspase-9 and caspase-3. In addition, we demonstrated that p38 mitogen-activated protein kinase was involved in the GA-mediated cell-cycle arrest and apoptosis. Collectively, our findings indicate that GA inhibits the cell viability of TNBC cells, which may attribute to the G1 phase arrest and cellular apoptosis via p38 mitogen-activated protein kinase/p21/p27 axis. Thus, we suggest that GA could be beneficial to TNBC treatment.

Bergapten is a natural compound and has potent anticancer activities. In this study, we explored the cytotoxicity of bergapten on colorectal cancer (CRC) cell DLD-1 and LoVo and its underlying mechanisms. We observed that bergapten (30 and 50 μM) decreased the viability of the CRC cells and induced the G0/G1 and sub-G1 phase arrest. Furthermore, immunoblotting results indicated that bergapten increased p53, phospho-p53(Ser-46), p21, PUMA, Bax, PTEN, and the caspase-9 and caspase-3 cleavage, but decreased cyclin E, CDK2, and phosphor-AKT(Ser-473) in the CRC cells. Inhibition of p53 by pifithrin-α reversed the bergapten-induced p53-mediated apoptotic cascade and restored the survival signaling and cell viability. Collectively, our findings reveal that bergapten decrease the cell viability and induce cell cycle arrest in the CRC cells, which may be attributed to p53-mediated apoptotic cascade, upregulation of p21 and PTEN, and inhibition of AKT. K E Y W O R D S apoptosis, colorectal cancer cells, Berga, PTEN, p21, p53

Background: Sesamin is a major bioactive compound in sesame seeds and has various biological properties, including anti-inflammatory and anticancer activities. Here, we explored whether sesamin activates p53, which is widely inhibited in cervical cancer cells, thereby inducing p53-mediated apoptosis. Methods: Human HeLa and SiHa cervical cancer cells and normal Hs68 dermal cells were used as cell models. Cell proliferation, cell cycle distribution, and apoptosis were evaluated by the CCK-8 assay and flow cytometry using PI/Annexin V staining, respectively. Protein expression and phosphorylation were determined using western blotting. The involvement of p53 in the apoptotic cascade was assessed by a specific inhibitor. Results: Sesamin (75 and 150 µM) clearly inhibited SiHa and HeLa cell proliferation in a dose-dependent fashion, but did not affect the proliferation of Hs68 cells. Meanwhile, sesamin increased the sub-G1 phase ratio and apoptosis, up to approximately 38.5% and 37.8%, respectively. Furthermore, sesamin induced p53 phosphorylation at serine-46 and serine-15 and upregulated the levels of PUMA, Bax, and PTEN, while inhibiting AKT phosphorylation at serine-473. Inhibition of p53 by pifithrin-α significantly reduced the levels of PUMA, Bax, and PTEN but restored AKT phosphorylation in SiHa cells exposed to sesamin. Pifithrin-α also reduced apoptosis and restored the proliferation of HeLa and SiHa cells exposed to sesamin. Conclusions: These findings indicate that sesamin inhibits cervical cancer cell proliferation, and its mechanism may be attributed to the induction of p53/PTEN-mediated apoptosis. This suggests that sesamin might be useful as an adjuvant in promoting anti-cervical cancer treatments.

Tumor necrosis factor alpha (TNFα) plays diverse roles in liver damage and hepatocarcinogenesis with its multipotent bioactivity. However, the influence of TNFα on protein expression of hepatocellular carcinoma (HCC) is incompletely understood. Therefore, we aimed to investigate the differential protein expression of HCC in response to TNFα stimulus. We observed that HepG2 cell revealed a higher resistance to TNFα-induced apoptosis as compared to the non-tumorigenic hepatocyte THLE-2. By using a label-free quantitative proteomic analysis, we found that 520 proteins were differentially expressed in the HepG2 cells exposed to TNFα, including 211 up-regulated and 309 down-regulated proteins. We further confirmed several proteins with significant expression change (TNFα/control ratio>2.0 or <0.5) by immunoblotting using specific antibodies. We also analyzed the differential expressed proteins using Gene ontology and KEGG annotations, and the results implicated that TNFα might regulate ribosome, spliceosome, antigen processing and presentation, and energy metabolism in HepG2 cells. Moreover, we demonstrated that upregulation of heat shock protein 70 (HSP70) was involved in both the promoted migration and the inhibited apoptosis of HepG2 cells in response to TNFα. Collectively, these findings indicate that TNFα alters protein expression such as HSP70, which triggering specific molecular processes and signaling cascades that promote migration and inhibit apoptosis of HepG2 cells.

The pr incipal subtype of lung cancer, non-small cell lung cancer (NSCLC) is a life-threatening malignancy that causes high mortality rates. Bergapten (5-methoxypsoralen) has been identified to possess anticancer activity against a number of carcinomas. In the present study, the effects of bergapten on NSCLC cells were investigated. The cell viability was determined by MTT assay. Cell cycle distribution was analyzed using flow cytometry. Protein expression and kinase cascade were demonstrated using western blot analysis. The results demonstrated that treatment with bergapten (50 µM for 48 h) inhibited the viability of A549 and NCI-H460 NSCLC cells to 79.1±2.8% and 74.5±3.1%, respectively, compared with the controls. It was identified that bergapten induced G1 phase accumulation in A549 and NCI-H460 cells between ~58 and 75% (P<0.01). In addition, bergapten significantly increased the sub-G1 phase ratio to ~9% (P<0.05) in the two cell types. Further investigation demonstrated that bergapten upregulated the expression of cellular tumor antigen p53 (p53) and its downstream proteins cyclin-dependent kinase inhibitor 1 and cyclin-dependent kinase inhibitor 1B, whereas, it downregulated the expression of cyclin D1 and CDK4. Overall, these results suggested that bergapten may inhibit cell viability and trigger G1 arrest and apoptosis in A549 and NCI-H460 cells, which may be attributed to the activation of p53-mediated cascades. Therefore, bergapten may be beneficial for NSCLC treatment.