Chong Zhang

Wnt/β-catenin signaling induces the aging of mesenchymal stem cells through promoting the ROS production.

Recent studies have demonstrated that the Wnt/β-catenin signaling plays an important role in stem cell aging. However, the mechanisms of cell senescence induced by Wnt/β-catenin signaling are still poorly understood. Our preliminary study has indicated that activated Wnt/β-catenin signaling can induce MSC aging. In this study, we reported that the Wnt/β-catenin signaling was a potent activator of reactive oxygen species (ROS) generation in MSCs. After scavenging ROS with N-acetylcysteine, Wnt/β-catenin signaling-induced MSC aging was significantly attenuated and the DNA damage and the expression of p16INK4A, p53, and p21 were reduced in MSCs. These results indicated that the Wnt/β-catenin signaling could induce MSC aging through promoting the intracellular production of ROS, and ROS may be the main mediators of MSC aging induced by excessive activation of Wnt/β-catenin signaling.

Role of p38 MAPK in enhanced human cancer cells killing by the combination of aspirin and ABT-737

Regular use of aspirin after diagnosis is associated with longer survival among patients with mutated‐PIK3CA colorectal cancer, but not among patients with wild‐type PIK3CA cancer. In this study, we showed that clinically achievable concentrations of aspirin and ABT‐737 in combination could induce a synergistic growth arrest in several human PIK3CA wild‐type cancer cells. In addition, our results also demonstrated that long‐term combination treatment with aspirin and ABT‐737 could synergistically induce apoptosis both in A549 and H1299 cells. In the meanwhile, short‐term aspirin plus ABT‐737 combination treatment induced a greater autophagic response than did either drug alone and the combination‐induced autophagy switched from a cytoprotective signal to a death‐promoting signal. Furthermore, we showed that p38 acted as a switch between two different types of cell death (autophagy and apoptosis) induced by aspirin plus ABT‐737. Moreover, the increased anti‐cancer efficacy of aspirin combined with ABT‐737 was further validated in a human lung cancer A549 xenograft model. We hope that this synergy may contribute to failure of aspirin cancer therapy and ultimately lead to efficacious regimens for cancer therapy.

In vitro anti-cancer activity of chamaejasmenin B and neochamaejasmin C isolated from the root of Stellera chamaejasme L.

Aim:To examine the anti-cancer effects of chamaejasmenin B and neochamaejasmin C, two biflavonones isolated from the root of Stellera chamaejasme L (known as the traditional Chinese herb Rui Xiang Lang Du) in vitro.Methods:Human liver carcinoma cell lines (HepG2 and SMMC-7721), a human non-small cell lung cancer cell line (A549), human osteosarcoma cell lines (MG63, U2OS, and KHOS), a human colon cancer cell line (HCT-116) and a human cervical cancer cell line (HeLa) were used. The anti-proliferative effects of the compounds were measured using SRB cytotoxicity assay. DNA damage was detected by immunofluorescence and Western blotting. Apoptosis and cell cycle distribution were assessed using flow cytometry analysis. The expression of the related proteins was examined with Western blotting analysis.Results:Both chamaejasmenin B and neochamaejasmin C exerted potent anti-proliferative effects in the 8 human solid tumor cell lines. Chamaejasmenin B (the IC50 values ranged from 1.08 to 10.8 μmol/L) was slightly more potent than neochamaejasmin C (the IC50 values ranged from 3.07 to 15.97 μmol/L). In the most sensitive A549 and KHOS cells, the mechanisms underlying the anti-proliferative effects were characterized. The two compounds induced prominent expression of the DNA damage marker γ-H2AX as well as apoptosis. Furthermore, treatment of the cells with the two compounds caused prominent G0/G1 phase arrest.Conclusion:Chamaejasmenin B and neochamaejasmin C are potential anti-proliferative agents in 8 human solid tumor cell lines in vitro via inducing cell cycle arrest, apoptosis and DNA damage.

Coenzyme Q10 Inhibits the Aging of Mesenchymal Stem Cells Induced by D-Galactose through Akt/mTOR Signaling

Increasing evidences indicate that reactive oxygen species are the main factor promoting stem cell aging. Recent studies have demonstrated that coenzyme Q10 (CoQ10) plays a positive role in organ and cellular aging. However, the potential for CoQ10 to protect stem cell aging has not been fully evaluated, and the mechanisms of cell senescence inhibited by CoQ10 are still poorly understood. Our previous study had indicated that D-galactose (D-gal) can remarkably induce mesenchymal stem cell (MSC) aging through promoting intracellular ROS generation. In this study, we showed that CoQ10 could significantly inhibit MSC aging induced by D-gal. Moreover, in the CoQ10 group, the expression of p-Akt and p-mTOR was clearly reduced compared with that in the D-gal group. However, after Akt activating by CA-Akt plasmid, the senescence-cell number in the CoQ10 group was significantly higher than that in the control group. These results indicated that CoQ10 could inhibit D-gal-induced MSC aging through the Akt/mTOR signaling.

Anti-metastatic effects of DNA vaccine encoding single‑chain trimer composed of MHC I and vascular endothelial growth factor receptor 2 peptide

Vascular endothelial growth factor receptor 2 (VEGFR2)-mediated signaling is the key rate-limiting step in angiogenesis. VEGFR2 serves as the most important target of anti-angiogenic therapy for cancers. Single-chain trimer (SCT) comprising antigen peptide, β2-microglobulin (β2m), and major histocompatibility complex (MHC) class I heavy chain was a particularly powerful strategy involved in the increase of the potency of DNA vaccine against tumors and infections. In the present study, we constructed an SCT-encoding VEGFR2 antigen peptide [aa400-408, also known as kinase insert domain-containing receptor (KDR2)], β2m, and mouse MHC class I heavy chain H-2Db [pcDNA3.1(+)-KDR2-β2m-H-2Db, or SCT-KDR2]. The constructed SCT-KDR2 DNA was efficiently expressed in the human A293 embryonic kidney cell line. Intradermal immunization of C57BL/6 mice with SCT-KDR2 DNA was able to successfully break self-immunological tolerance and induce robust cytotoxic T‑lymphocyte (CTL) response to VEGFR2, leading to marked suppression of tumor cell‑induced angiogenesis and metastasis in murine models of B16 melanoma and 3LL Lewis lung carcinoma. Taken together, the results showed that VEGFR2-targeted SCT vaccination is an effective modality that can be utilized in anti-angiogenic active immunotherapy for various types of cancer.

Evodiamine induces apoptosis and enhances apoptotic effects of erlotinib in wild-type EGFR NSCLC cells via S6K1-mediated Mcl-1 inhibition

Erlotinib is effective in NSCLC patients with known drug-sensitizing EGFR mutations, but its clinical efficacy in patients with wild-type EGFR or acquired resistance to erlotinib remains modest. Evodiamine is a chemical extracted from the Evodia rutaecarpa (Juss.) Benth, we showed that evodiamine could induce anti-proliferation and apoptosis in four wild-type EGFR NSCLC cell lines, and combining evodiamine with erlotinib might successfully inhibit cell proliferation and survival in wild-type EGFR NSCLC cells, characterized as erlotinib-resistant. In addition, evodiamine plus erlotinib significantly increased the apoptotic rate of NSCLC cells, as compared to single agent treatment alone. Further investigation of the mechanism underlying these effects revealed that evodiamine plus erlotinib might downregulate Mcl-1 expression through the mTOR/S6K1 control of its translation. Thus, our study has revealed evodiamine as a pertinent sensitizer to erlotinib and the strategy of combining erlotinib with evodiamine appears to be an attractive option for reversing resistance to erlotinib.

High glucose induces the aging of mesenchymal stem cells via Akt/mTOR signaling

It has previously been demonstrated that glucose is important in the process of stem cell aging. However, the mechanisms of cell senescence induced by high glucose (HG) remain to be elucidated. The preliminary study indicated that D-galactose induced mesenchymal stem cell (MSCs) aging. The present study demonstrated, following treatment with 11.0 or 22.0 mM HG for 14 days, that HG significantly promoted MSCs aging and the expression levels of phosphorylated (p-)phosphatidylinositol 3-kinase/protein kinase B (Akt) and p-mammalian target of rapamycin signaling (mTOR) in the HG groups were increased compared with the control group. However, following Akt inhibition with 1.0 or 10.0 nM MK-2206, which is an Akt-specific small molecule inhibitor, the senescence-cell value in the HG group was significantly decreased compared with the control group. These results indicated that HG induced MSCs senescence and this effect was primarily mediated via the Akt/mTOR signaling pathway.

Enhanced antitumor activity by the combination of dasatinib and combretastatin A-4 in vitro and in vivo

The present study showed that the combination of dasatinib and combretastatin A-4 (CA-4) exhibited synergistic cytotoxicity in multiple types of cancer, including ovarian, hepatocellular, lung and prostate carcinoma. The enhanced apoptosis induced by dasatinib plus CA-4 was accompanied by a greater extent of mitochondrial depolarization, caspase-3 activation and PARP cleavage in HO-8910 cells. Furthermore, elevated expression of Mcl-1 led to a reduced apoptosis induced by dasatinib plus CA-4, highlighting that downregulated Mcl-1 was necessary for the potentiating effect of dasatinib to CA-4-triggered apoptosis. A clear increase in γ-H2AX expression was observed in the dasatinib+CA-4 group compared with the mono-treatment groups, indicating that dasatinib plus CA-4 may induce double-strand breaks (DSBs) in HO-8910 cells. Moreover, the increased anticancer efficacy of dasatinib combined with CA-4 was further validated in a human HO-8910 ovarian cancer xenograft model in nude mice. Our study is the first to show that the combination of dasatinib with CA-4 could be a novel and promising therapeutic approach for the treatment of cancer.

Synergistic antitumor activity of aspirin and erlotinib: Inhibition of p38 enhanced aspirin plus erlotinib‑induced suppression of metastasis and promoted cancer cell apoptosis

High-dose erlotinib is effective for non-small cell lung cancer patients with brain metastases. The aim of the present study was to investigate whether aspirin could increase the anti-proliferative and anti-metastatic effects of regular erlotinib treatment. The data demonstrated that combining aspirin with erlotinib significantly induced apoptosis and inhibited tumor cell proliferation in several human cancer types. Furthermore, aspirin plus erlotinib significantly induced the activation of E-cadherin and suppression of p38. The data also indicated that the p38/E-cadherin pathway may be involved in the apoptosis caused by the combination of aspirin and erlotinib. As p38 and E-cadherin also serve a key role in epithelial-to-mesenchymal transition (EMT) and cancer metastasis, we hypothesized that the combination of aspirin and erlotinib may significantly inhibit tumor metastasis. First, aspirin plus erlotinib achieved potent inhibition of cancer cell migration and invasion, which are crucial for cancer metastasis. Next, the results demonstrated that aspirin plus erlotinib inhibited angiogenesis by suppressing endothelial cell migration and invasion. Moreover, it was confirmed that aspirin plus erlotinib exerted synergistic anti-angiogenic effects. Finally, the synergistic anti-proliferative and anti-metastatic effects of the combination of aspirin with erlotinib were further validated in an A549 xenograft model in vivo. In conclusion, aspirin plus erlotinib may be an effective combination regimen for patients with metastatic cancer.

Shikonin sensitizes wild‑type EGFR NSCLC cells to erlotinib and gefitinib therapy

As patients with non-small cell lung cancer (NSCLC) and wild-type epidermal growth factor receptor (EGFR) are resistant to treatment with erlotinib or gefitinib, potential chemosensitizers are required to potentiate wild-type EGFR NSCLC cells to erlotinib/gefitinib treatment. The present study reported that shikonin could sensitize the anticancer activity of erlotinib/gefitinib in wild-type EGFR NSCLC cells. Furthermore, shikonin could potentiate mitochondrial-mediated apoptosis induced by erlotinib/gefitinib in wild-type 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 wild-type EGFR NSCLC cells; however, shikonin plus erlotinib/gefitinib was more effective in activating ER stress than either agent alone. This indicated that ROS-mediated 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 stress-inducing EGFR-tyrosine kinase inhibitor tolerance to apoptosis-promoting ER stress. Furthermore, shikonin may enhance the anti-NSCLC activity of erlotinib/gefitinib in vivo. The data of the present study indicated that shikonin may be a potential sensitizer to enhance the anti-cancer efficacy of erlotinib/gefitinib in wild-type EGFR NSCLC cells resistant to erlotinib/gefitinib treatment.