ABT-737 potentiates cisplatin-induced apoptosis in human osteosarcoma cells via the mitochondrial apoptotic pathway

Synergistic cytotoxicity of perifosine and ABT-737 to colon cancer cells

An acidic environment and hypoxia within the tumour are hallmarks of cancer that contribute to cell resistance to therapy. Deregulation of the PI3K/Akt pathway is common in colon cancer. Numerous Akt-targeted therapies are being developed, the activity of Akt-inhibitors is, however, strongly pH-dependent. Combination therapy thus represents an opportunity to increase their efficacy. In this study, the cytotoxicity of the Akt inhibitor perifosine and the Bcl-2/Bcl-xL inhibitor ABT-737 was tested in colon cancer HT-29 and HCT-116 cells cultured in monolayer or in the form of spheroids. The efficacy of single drugs and their combination was analysed in different tumour-specific environments including acidosis and hypoxia using a series of viability assays. Changes in protein content and distribution were determined by immunoblotting and a "peeling analysis" of immunohistochemical signals. While the cytotoxicity of single agents was influenced by the tumour-specific microenvironment, perifosine and ABT-737 in combination synergistically induced apoptosis in cells cultured in both 2D and 3D independently on pH and oxygen level. Thus, the combined therapy of perifosine and ABT-737 could be considered as a potential treatment strategy for colon cancer.

Cisplatin and Exogenous Hydrogen Sulfide Inhibit the Progression of Osteosarcoma via EGFR/P13K/Akt Signaling Pathway

We attempted to analyze the effects of cisplatin and exogenous hydrogen on the invasion and proliferation of human osteosarcoma cells through EGFR/P13K/Akt signaling pathway. The effects of exogenous hydrogen sulfide and cisplatin on the invasion, apoptosis and proliferation of MG-63 cells were detected by transwell chamber invasion experiment, flow cytometry and CCK-8 method. After 24 and 48 hours of drug action, the inhibition rate of cell proliferation was significantly higher than in the combined treatment. The number of cells decreased significantly, compared with the control group. Western blotting and qRT-PCR showed that the expression of Akt mRNA in MG-63 cells treated with cisplatin+hydrogen sulfide at different concentrations for 48 hours decreased. The expression of Akt, P13K and EGFR were decreased Flow cytometry analysis showed that after the drug treatment of MG-63 cells, the S phase of cisplatin and cisplatin+exogenous hydrogen concentrations with different prolonged concentrations was significantly shortened phase and the G0/G1 was significantly, and the apoptosis rate of each group was significantly increased. Cisplatin and exogenous hydrogen sulfide can synergistically inhibit the proliferation and invasion of human osteosarcoma MG-63 cells, and regulate the apoptosis mechanism of MG-63 cells through EGFR/P13K/Akt signaling pathway.

BH3-mimetics: recent developments in cancer therapy

The hopeful outcomes from 30 years of research in BH3-mimetics have indeed served a number of solid paradigms for targeting intermediates from the apoptosis pathway in a variety of diseased states. Not only have such rational approaches in drug design yielded several key therapeutics, such outputs have also offered insights into the integrated mechanistic aspects of basic and clinical research at the genetics level for the future. In no other area of medical research have the effects of such work been felt, than in cancer research, through targeting the BAX-Bcl-2 protein-protein interactions. With these promising outputs in mind, several mimetics, and their potential therapeutic applications, have also been developed for several other pathological conditions, such as cardiovascular disease and tissue fibrosis, thus highlighting the universal importance of the intrinsic arm of the apoptosis pathway and its input to general tissue homeostasis. Considering such recent developments, and in a field that has generated so much scientific interest, we take stock of how the broadening area of BH3-mimetics has developed and diversified, with a focus on their uses in single and combined cancer treatment regimens and recently explored therapeutic delivery methods that may aid the development of future therapeutics of this nature.

Dual Akt and Bcl-2 inhibition induces cell-type specific modulation of apoptotic and autophagic signaling in castration resistant prostate cancer cell lines

BACKGROUND

Cancer cell survival depends on the cross-regulation between apoptosis and autophagy which share common signaling pathways including PI3K/Akt/mTOR and Bcl-2. The aim of this study was to elucidate the modulation patterns between apoptosis and autophagy following dual inhibition by Akt inhibitor erufosine and Bcl-2 inhibitor ABT-737 in castration-resistant prostate cancer (CRPC) cell lines, PC-3 (Bax+) and DU-145 (Bax-).

METHODS AND RESULTS

Cell cycle progression, apoptotic and autophagic signaling were examined by flow cytometry, multi-caspase assay, Hoechst staining, acridine orange staining of acidic vesicular organelles (AVOs), qRT-PCR and Western Blot. Dual inhibition increased G2/M arrest in PC-3 and DU-145, but not in the healthy prostate epithelium cells, PNT-1A. Only in PC-3, dual inhibition induced synergistic apoptotic and additive autophagic effects. In DU-145 and PNT-1A cells, ABT-737 did not display any remarkable effect on multicaspase activity and erufosine and ABT-737, neither alone nor in combination induced AVOs. By dual inhibition, AKT, BCL-2 and NF-κB gene expressions were downregulated in PC-3, both ATG-5 and BECLIN-1 gene expressions were upregulated in DU-145 but Beclin-1 protein expression was substantially reduced in both CRPC cells. Dual inhibition-induced synergistic multicaspase activation in PC-3 degrades and disrupts autophagic activity of Beclin-1, enhancing caspase-dependent apoptosis. However, in DU-145, following dual inhibition, rate of multicaspase induction and apoptosis are lower but autophagy is completely abolished despite markedly increased BECLIN-1 gene expression.

CONCLUSION

In conclusion, antineoplastic drug combinations may display cell-type specific modulation of apoptotic and autophagic signaling and lack of protective autophagy may not necessarily indicate increased chemotherapeutic sensitivity in heterogenous tumor subpopulations.

Severe cellular stress activates apoptosis independently of p53 in osteosarcoma

Apoptosis induced by doxorubicin, bortezomib, or paclitaxel, targeting DNA, 26S proteasome, and microtubules respectively, was assessed in two osteosarcoma cells, p53 wild-type U2OS and p53-null MG63 cells. Doxorubicin-induced apoptosis only occurred in U2OS, not in MG63. In contrast, bortezomib and paclitaxel could drive U2OS or MG63 toward apoptosis effectively, suggesting that apoptosis induced by bortezomib or paclitaxel is p53-independent. The expressions of Bcl2 family members such as Bcl2, Bcl-xl, and Puma could be seen in U2OS and MG63 cells with or without doxorubicin, bortezomib, or paclitaxel treatment. In contrast, another member, Bim, only could be observed in U2OS, not in MG63, under the same conditions. Bim knockdown did not affect the doxorubicin-induced apoptosis in U2OS, suggested that a BH3-only protein other than Bim might participate in apoptosis induced by doxorubicin. Using a BH3-mimetic, ABT-263, to inhibit Bcl2 or Bcl-xl produced a limited apoptotic response in U2OS and MG63 cells, suggesting that this BH3-mimetic cannot activate the Bax/Bak pathway efficiently. Significantly, ABT-263 enhanced doxorubicin- and bortezomib-induced apoptosis synergistically in U2OS and MG63 cells. These results implied that the severe cellular stress caused by doxorubicin or bortezomib might be mediated through a dual process to control apoptosis. Respectively, doxorubicin or bortezomib activates a BH3-only protein in one way and corresponding unknown factors in another way to affect mitochondrial outer membrane permeability, resulting in apoptosis. The combination of doxorubicin with ABT-263 could produce synergistic apoptosis in MG63 cells, which lack p53, suggesting that p53 has no role in doxorubicin-induced apoptosis in osteosarcoma. In addition, ABT-263 enhanced paclitaxel to induce moderate levels of apoptosis.

Programmed cell death, redox imbalance, and cancer therapeutics

Cancer cells are disordered by nature and thus featured by higher internal redox level than healthy cells. Redox imbalance could trigger programmed cell death if exceeded a certain threshold, rendering therapeutic strategies relying on redox control a possible cancer management solution. Yet, various programmed cell death events have been consecutively discovered, complicating our understandings on their associations with redox imbalance and clinical implications especially therapeutic design. Thus, it is imperative to understand differences and similarities among programmed cell death events regarding their associations with redox imbalance for improved control over these events in malignant cells as well as appropriate design on therapeutic approaches relying on redox control. This review addresses these issues and concludes by bringing affront cold atmospheric plasma as an emerging redox controller with translational potential in clinics.

The ratio of Bcl-2/Bim as a predictor of cisplatin response provides a rational combination of ABT-263 with cisplatin or radiation in small cell lung cancer

BACKGROUND

Cisplatin-based chemotherapy and radiotherapy are the most commonly used treatments for small cell lung cancer (SCLC). However, despise initially dramatic response, the response duration of SCLC patients is variable and resistance to chemo- and radio-therapy inevitably develops.

OBJECTIVE

The aim of the study is to investigate the role of Bcl-2 family proteins in predicting SCLC sensitivity to cisplatin treatment, and to identify the potential sensitizer of cisplatin or ratiation treatment in SCLC.

METHODS

We collected cisplatin sensitivity data from public available database, and evaluated its possible association with mRNA or protein expression of Bcl-2 family members in SCLC cell lines.

RESULTS

The IC50 value of cisplatin was significantly correlated with the ratio of Bcl-2/Bim mRNA expression in 33 SCLC cell lines (P= 0.041) as well as the ratio of Bcl-2/Bim protein expression in 7 SCLC cell lines (P= 0.0252). Furthermore, a BH3-mimetic ABT-263 was found to be able to sensitize SCLC cells to cisplatin or radiation. The synergistic and additive antitumor activity of ABT-263 combined with cisplatin or radiation was associated with the enhanced apoptosis, which may be caused by the disruption of Bcl-2 binding to Bim by ABT-263.

CONCLUSIONS

Our study indicates that the ratio of Bcl-2/Bim could be a SCLC response predictor to cisplatin, and ABT-263 addition could be an effective strategy to improve the activity of chemo- or radio-therapy in SCLC.

Suppression of YAP by DDP disrupts colon tumor progression

Colon cancer is a commonly diagnosed cancer that often has a poor prognosis. Combined with the development of drug resistance to cancer treatment agents the treatment efficacy of colon cancer can be limited. Activation of the oncogene YAP has been shown to be related to colon cancer progression and is associated with poor prognosis, drug resistance and metastasis, even under treatment. Cisplatin (DDP) is a commonly used drug that can control carcinoma progression, although its mechanisms are poorly understood. In the present study, we examined whether DDP specifically suppressed YAP in order to inhibit colon carcinoma progression. Our data revealed that Mst/Yap signaling was unusually activated in colon cancers, promoting cell proliferation and invasion. DDP treatment decreased the expression of YAP at both the transcriptional and post-translational levels, leading to cell cycle arrest, apoptosis and senescence in cancer cells, in addition to decreasing epithelial-to-mesenchymal transition, cell motility and in vitro cell invasion and migration. Ultimately, DDP increased the expression of E-cadherin and decreased the expression of vimentin. The present study also revealed that post-translational regulation of YAP phosphorylation controlled the subcellular distribution between the nucleus and the cytoplasm. In conclusion, the findings of the present study revealed that DDP was a suitable therapeutic candidate for colon cancer that specifically targets the Mst/Yap signaling pathway.

Daidzein induces choriocarcinoma cell apoptosis in a dose-dependent manner via the mitochondrial apoptotic pathway

Choriocarcinoma is a malignant gestational trophoblastic disease and relapse or drug resistance occurs in ~25% of gestational trophoblastic tumors. Cell apoptosis serves a role in the progression from hydatidiform mole to persistent gestational trophoblastic disease. It has been demonstrated that daidzein [7‑hydroxy‑3‑(4‑hydroxyphenyl)‑4H‑chromen‑4‑one] may induce apoptosis in a number of cancer types via the mitochondrial apoptotic pathway by altering the B‑cell lymphoma (Bcl)‑2/Bcl‑2 associated X, apoptosis regulator (Bax) ratio, and activating the caspase cascade. Daidzein also serves a role in regulation of production of human chorionic gonadotropin in trophoblast cells and inhibition of cell proliferation. However, few reports have been published regarding the effect of daidzein on apoptosis in choriocarcinoma. Therefore, in the present study, JAR and JEG‑3 human gestational choriocarcinoma cells were used to investigate the effect of daidzein on apoptosis of choriocarcinoma cells. Treatment with daidzein for 48 h reduced cell viability in a dose‑dependent manner. The percentages of early and late apoptotic cells also increased following treatment with daidzein in a dose‑dependent manner, with the number of late apoptotic cells increasing more prominently. Furthermore, treatment with daidzein led to apoptosis‑associated alterations in nuclear morphology of JAR and JEG-3 cells. Expression levels of cleaved poly(ADP‑ribose) polymerase, cleaved caspase‑3 and cleaved caspase‑9 increased following treatment with daidzein, whereas the Bcl‑2/Bax ratio decreased in a dose‑dependent manner. In conclusion, the results of the present study demonstrate that daidzein may induce apoptosis of choriocarcinoma cells in a dose‑dependent manner via the mitochondrial apoptotic pathway.

8-Chrysoeriol, as a potential BCL-2 inhibitor triggers apoptosis of SW1990 pancreatic cancer cells

8-Chrysoeriol, a bioactive flavanoid, was firstly identified to bind directly to BCL-2 as BH3 mimetics by structure-based virtual ligand screening. And 3D docking model revealed the molecular basis of 8-Chrysoeriol targeting to BCL-2. The interaction between 8-Chrysoeriol and BCL-2 was further confirmed using Microscale Thermophoresis (MST) technique. Meanwhile, high expression level of antiapoptotic protein BCL-2 was detected in SW1990 pancreatic cancer cells and 8-Chrysoeriol showed obvious proapoptosis effect against SW1990 in vitro. Collectively, the results showed that 8-Chrysoeriol as a natural dietary product potentially targeting to BCL-2 could serve as a lead compound for SW1990 pancreatic cancer therapy.