Triacanthine enhances the sensitivity of colorectal cancer cells to 5-fluorouracil by regulating RRM2.

BACKGROUND: According to the literatures, triacanthine is isolated from the leaves of Gleditsia triacanthos L. and acts as an anti-hypertensive agent, also cardiotonic, antispasmodic and a respiratory analeptic. The 5-fluorouracil (5-FU) is widely used to treat the patients of colorectal cancer (CRC), but the resistance to 5-FU treatment restricts the therapeutic efficacy of CRC patients. PURPOSE: This study aims to explore a novel therapeutics regimen overcoming CRC resistance to 5-FU. METHODS: The cell proliferation of CRC cells was determined by SRB and colony formation assay. Transwell and wound-healing assay were applied to explore the potential metastatic abilities of CRC cells. qRT-PCR and Western blot were performed to evaluate the level of indicated mRNAs and proteins respectively. Xenograft assay was used to explore the anti-CRC effect of triacanthine. RESULTS: Triacanthine statistically restrained CRC proliferation both in vitro and in vivo. Triacanthine induced cell cycle G1/G0 phase arrest in CRC cells. Meanwhile, triacanthine also inhibited the migrative and invasive abilities of CRC cells. A Venn diagram was generated showing that O-6-Methylguanine-DNA Methyltransferase (MGMT) might be a molecular target of triacanthine in treating CRC. Furthermore, triacanthine plus 5-FU significantly suppressed the cell proliferation of CRC cells compared with single agent treatment alone, and highly synergistic anti-cancer effects were scored when 5-FU was combined with triacanthine in CRC cells. In addition, triacanthine sensitized the anti-cancer activity of 5-FU via regulating Ribonucleotide Reductase Regulatory Subunit M2 (RRM2). MGMT or RRM2 might be novel biomarkers for evaluating the therapeutical efficiency of 5-FU in CRC patients. CONCLUSION: We firstly demonstrated triacanthine suppressed cell proliferation and metastasis abilities and found the novel molecular targets of triacanthine in CRC cells. This is the first study to evaluate the anti-cancer efficiency of triacanthine plus 5-FU. Our study has revealed triacanthine as a pertinent sensitizer to 5-FU, and provided novel strategies for predicting outcomes and reversing resistance of 5-FU therapy.

A natural anthraquinone derivative shikonin synergizes with AZD9291 against wtEGFR NSCLC cells through reactive oxygen species-mediated endoplasmic reticulum stress.

BACKGROUND: NSCLC is the major type of lung cancer and the survival rates of NSCLC patients remain low. AZD9291 is a third-generation EGFR-TKI and approved to treat NSCLC patients harboring EGFR T790M mutation and common targetable activating EGFR mutations, but it has a limited effect for wtEGFR NSCLC. PURPOSE: The current study investigated whether shikonin could enhance the antitumor effect of AZD9291 in wtEGFR NSCLC cells. METHODS: SRB and colony formation assay were used to detect the proliferation of NSCLC cells, propidium iodide staining was performed to detect the apoptosis, ROS was analyzed using DCFH-DA staining, and western blot was used to detect the expression of indicated proteins. RESULTS: We demonstrated that shikonin, a natural ROS inducer, could enhance the antitumor effect of AZD9291 in wtEGFR NSCLC cells. In addition, shikonin increased AZD9291-induced apoptosis accompanying with the generation of ROS and activation of ER stress. Furthermore, ROS inhibition by NAC or GSH reversed the apoptosis induced by shikonin plus AZD9291, and recovered the ER stress activated by combination treatment, indicating that ROS mediated ER stress played a vital role in this combination therapy. Moreover, shikonin increased the anticancer activity of AZD9291 in primary wtEGFR NSCLC cells through ROS-mediated ER stress. CONCLUSION: Our study suggests that combining shikonin with AZD9291 is a promising therapeutic strategy for treating wtEGFR NSCLC patients.

BAY 87-2243 sensitizes hepatocellular carcinoma Hep3B cells to histone deacetylase inhibitors treatment via GSK-3ß activation.

Hepatocellular carcinoma (HCC) is associated with some of the highest cancer-associated mortality rates. Histone deacetylase (HDAC) inhibitors anti-HCC activities have been shown to promote Snail-induced metastasis. In the present study, it was shown that BAY 87-2243, a hypoxia-inducible transcription factor-1α inhibitor, could enhance the anti-HCC effects of HDAC inhibitors, including trichostatin A and vorinostat. In addition, BAY 87-2243 plus HDAC inhibitors exhibited synergistic cytotoxicity and induced significant cell death in Hep3B cells. Additionally, BAY 87-2243 combined with HDAC inhibitors-treated Hep3B cells formed fewer and smaller colonies as compared with either the control or single agent-treated cells. Furthermore, glycogen synthase kinase-3ß might be involved in the enhanced cell death induced by BAY 87-2243 plus HDAC inhibitors. The present data also indicated that BAY 87-2243 combined with HDAC inhibitors could suppress the migration of Hep3B cells, and BAY 87-2243 could reverse the HDAC inhibitor-induced Snail activation in Hep3B cells. In conclusion, BAY 87-2243 combined with HDAC inhibitors might be an attractive chemotherapy strategy for HCC therapy.

Shikonin sensitizes wild­type EGFR NSCLC cells to erlotinib and gefitinib therapy.

As patients with non­small cell lung cancer (NSCLC) and wild­type epidermal growth factor receptor (EGFR) are resistant to treatment with erlotinib or gefitinib, potential chemosensitizers are required to potentiate wild­type EGFR NSCLC cells to erlotinib/gefitinib treatment. The present study reported that shikonin could sensitize the anticancer activity of erlotinib/gefitinib in wild­type EGFR NSCLC cells. Furthermore, shikonin could potentiate mitochondrial­mediated apoptosis induced by erlotinib/gefitinib in wild­type EGFR NSCLC cells. In addition, the present study demonstrated that shikonin could induce apoptosis by activating reactive oxygen species (ROS)­mediated endoplasmic reticulum (ER) stress, and that erlotinib/gefitinib may also induce ER stress in wild­type EGFR NSCLC cells; however, shikonin plus erlotinib/gefitinib was more effective in activating ER stress than either agent alone. This indicated that ROS­mediated ER stress may be associated with enhanced mitochondrial apoptosis induced by shikonin plus erlotinib/gefitinib. In addition, shikonin may promote the transition of cytoprotective ER stress­inducing EGFR­tyrosine kinase inhibitor tolerance to apoptosis­promoting ER stress. Furthermore, shikonin may enhance the anti­NSCLC activity of erlotinib/gefitinib in vivo. The data of the present study indicated that shikonin may be a potential sensitizer to enhance the anti­cancer efficacy of erlotinib/gefitinib in wild­type EGFR NSCLC cells resistant to erlotinib/gefitinib treatment.

Deacetylisovaltratum disrupts microtubule dynamics and causes G2/M-phase arrest in human gastric cancer cells in vitro.

AIM: Deacetylisovaltratum (DI) is isolated from the traditional Chinese herbal medicine Patrinia heterophylla Bunge, which exhibits anti-cancer activity. Here, we investigated the effects of DI on human gastric carcinoma cell lines in vitro and elucidated its anti-cancer mechanisms. METHODS: Human gastric carcinoma AGS and HGC-27 cell lines were treated with DI, and cell viability was detected with MTT assay. Cell cycle stages, apoptosis and mitochondrial membrane potential were measured using flow cytometry. Protein levels were analyzed by Western blotting. Tubulin polymerization assays and immunofluorescence were used to characterize the tubulin polymerization process. RESULTS: DI inhibited the cell viability of AGS and HGC-27 cells in a dose- and time-dependent manner with IC50 values of 12.0 and 28.8 µmol/L, respectively, at 24 h of treatment. Treatment with DI (10-100 µmol/L) dose-dependently promoted tubulin polymerization, and induced significant G2/M cell cycle arrest in AGS and HGC-27 cells. Moreover, DI treatment disrupted mitochondrial membrane potential and induced caspase-dependent apoptosis in AGS and HGC-27 cells. CONCLUSION: DI induces G2/M-phase arrest by disrupting tubulin polymerization in human gastric cancer cells, which highlights its potent anti-cancer activity and potential application in gastric cancer therapy.

S-allylcysteine, a garlic derivative, suppresses proliferation and induces apoptosis in human ovarian cancer cells in vitro.

AIM: To investigate the effects of S-allylcysteine (SAC), a water-soluble garlic derivative, on human ovarian cancer cells in vitro. METHODS: Human epithelial ovarian cancer cell line A2780 was tested. Cell proliferation was examined with CCK-8 and colony formation assays. Cell cycle was analyzed with flow cytometry. Cell apoptosis was studied using Hoechst 33258 staining and Annexin V/PI staining with flow cytometry. The migration and invasion of A2780 cells were examined with transwell and wound healing assays. The expression of relevant proteins was detected with Western blot assays. RESULTS: SAC (1-100 mmol/L) inhibited the proliferation of A2780 cells in dose- and time-dependent manners (the IC50 value was approximately 25 mmol/L at 48 h, and less than 6.25 mmol/L at 96 h). Furthermore, SAC dose-dependently inhibited the colony formation of A2780 cells. Treatment of A2780 cells with SAC resulted in G1/S phase arrest and induced apoptosis, accompanied by decreased expression of pro-caspase-3, Parp-1 and Bcl-2, and increased expression of active caspase-3 and Bax. SAC treatment significantly reduced the migration of A2780 cells, and markedly decreased the protein expression of Wnt5a, p-AKT and c-Jun, which were the key proteins involved in proliferation and metastasis. CONCLUSION: SAC suppresses proliferation and induces apoptosis in A2780 ovarian cancer cells in vitro.

Anti-tumor and apoptotic effects in vitro and in vivo of a traditional Chinese medicine prescription.

BACKGROUND: Zhongfei Mixture (ZM), a traditional Chinese medicine, exploited from the clinical experience, has mainly been used for the treatment of advanced lung cancer since it was produced in 1983. However, little research has been conducted on its anti-tumor mechanism. In this study, we aimed to investigate the anti-tumor and apoptotic effects of ZM in vitro and in vivo. METHODS: The growth inhibition effect of ZM on A549 cells was evaluated by MTT assay. Morphological observation and clone forming tests were performed to determine the effect of ZM on cell viability. Cell cycle distribution and apoptosis were analyzed by flow cytometry. In addition, the in vivo anti-proliferation activity of ZM was evaluated using mice bearing Lewis lung carcinoma. Further, the apoptosis of cells in tumor tissue was determined by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, and the expression of Ki-67 protein in tumor tissues was analyzed by En-Vision immuno-histochemistry staining. RESULTS: ZM exerted an obvious inhibitory effect on proliferation of A549 cells. It arrested A549 cells in G(2)-M phase and induced apoptosis. Compared with 3.02% and 5.32% in control group, the percentages of cells arrested in G(2)-M phase were 19.20% and 19.58% in 7.94 mg/ml ZM treated A549 cells at 24 hours and 48 hours. Moreover, the apoptosis rate increased from 0.18% to 18.01% after ZM treatment for 48 hours. ZM also significantly inhibited tumor growth in the tumor-implanted mice. Compared with saline control group, the effects of ZM showed significant tumor growth inhibition (P < 0.05). Furthermore, ZM could down-regulate the expression of Ki-67 in tumor tissue in mice bearing Lewis lung carcinoma. CONCLUSIONS: Our results indicated that ZM has notable anti-tumor effect and the effects of ZM in moderate dose groups were superlative both in vitro and in vivo. The possible mechanism of ZM might be associated with arresting cell cycle in G(2)-M phase as well as down-regulating Ki-67 expression in tumor tissues.