ZGDHu-1 promotes apoptosis of chronic lymphocytic leukemia cells

3,6-dichloro-1,2,4,5-Tetrazine Assayed at High Doses in the Metastatic Breast Cancer Cell Line MDA-MB-231 Reduces Cell Numbers and Induces Apoptosis

Background:

The lack of treatment options for patients with chemotherapy-resistant cancers is pushing the field toward the development of new therapies. 1,2,4,5-tetrazine derivatives are a class of heterocyclic compounds that exhibit a broad spectrum of antitumor activities.

Objective:

The purpose of this study was to assess the biological activity of four s-tetrazine derivatives by substitution of two chloride atom of 3,6-dichloro-1,2,4,5-tetrazine with long hydrophobic side chains.

Methods:

We analyzed the anti-proliferative effects of four s-tetrazine derivatives with MTT assay and their pro-apoptotic effect with AV/ IP flow cytometry analysis and Hoechst 33342 staining.

Results:

We demonstrated that 3,6-dichloro-1,2,4,5-tetrazine (compound (1)) has a cytotoxic effect and induces apoptosis.

Conclusion:

3,6-dichloro-1,2,4,5-tetrazine presents a new cytotoxic drug against metastatic breast cancer cell line MDA-MB-231 in vitro.

Induction of Apoptosis by an Extract of Persian Gulf Marine Mollusc, Turbo Coronatus through the Production of Reactive Oxygen Species in Mouse Melanoma Cells

Objective: A variety of approaches such as surgery, chemotherapy, radiotherapy, hormonal therapy and immunotherapy are used to treat melanomas, but unfortunately in most case, the response is very weak and often side effects are serious. This study concerns selective toxicity of an extract of Turbo coronatus on cells and mitochondria from a syngeneic mouse model of melanoma. Methods: Cells and mitochondria isolated from extra tumoral and melanoma tissues were exposed toa T. coronatus crude extract and fractions obtained by gel-filtration chromatography and assayed for mitochondrial and cellular parameters. Result: Crude extract (375, 750 and 1,500 μg/ml) and fraction 1; F1; (275, 550 and 1100 μg/ml) of T. coronatus extract induced a significant (p<0.05) increase of the reactive oxygen species (ROS) level, swelling of mitochondria, collapse of mitochondrial membrane potential (MMP), release of cytochrome c and caspase-3 activation only in the mitochondria and cells obtained from melanoma but not extra tumoral tissues. In addition, the F1 fraction decreased the percentage of viable cells and induced apoptosis in melanoma cells. Conclusion: For the first time we could demonstrate that the F1 fraction of a T. coronatus extract, selectively induces ROS mediated cytotoxicity by directly targeting mitochondria in melanoma tissues and it may be a suitable candidate for novel drug treatment of malignant melanomas.

Targeting Mitochondrial Bioenergetics as a Therapeutic Strategy for Chronic Lymphocytic Leukemia

Altered cellular metabolism is considered a hallmark of cancer and is fast becoming an avenue for therapeutic intervention. Mitochondria have recently been viewed as an important cellular compartment that fuels the metabolic demands of cancer cells. Mitochondria are the major source of ATP and metabolites necessary to fulfill the bioenergetics and biosynthetic demands of cancer cells. Furthermore, mitochondria are central to cell death and the main source for generation of reactive oxygen species (ROS). Overall, the growing evidence now suggests that mitochondrial bioenergetics, biogenesis, ROS production, and adaptation to intrinsic oxidative stress are elevated in chronic lymphocytic leukemia (CLL). Hence, recent studies have shown that mitochondrial metabolism could be targeted for cancer therapy. This review focuses the recent advancements in targeting mitochondrial metabolism for the treatment of CLL.

ZGDHu-1 for cancer therapy

N,N'-di-(m-methylphenyl)-3,6-dimethyl-1,4-dihydro-1,2,4,5-tetrazine-1,4-dicarboamide (ZGDHu-1) is a novel tetrazine derivative that was initially designed and produced by Professor W.X. Hu, and which has been reported by our group to exhibit antitumor activity. Accumulating evidence suggests that the anticancer mechanisms of ZGDHu-1 may be involved indifferent biological activities, particularly in acute myeloid leukemia (AML) cells. At a high concentration, ZGDHu-1 has been demonstrated to inhibit the proliferation of the leukemia cells by arresting the cell cycle at the G₂/M phase, and by inducing cell apoptosis via inducing the accumulation of reactive oxygen species, the translocation of phosphatidylserine across the plasma membrane and the loss of mitochondrial membrane potential. Furthermore, at a low concentration, it was demonstrated to induce the differentiation and degrade the AML1-eight-twenty-one fusion protein in AML cells. Finally, results from a previous study indicate that ZGDHu-1 is a potential proteasome inhibitor. Overall, our preliminary research suggests that ZGDHu-1 may be a promising anticancer drug; however, further research is warranted to identify the exact drug target and potential clinical application in leukemia cells or solid tumors. In the present review, the application of ZGDHu-1 in cancer research, in addition to the specific underlying targets of ZGDHu-1, are discussed.

Naja Naja Oxiana Venom Fraction Selectively Induces ROS-Mediated Apoptosis in Human Colorectal Tumor Cells by Directly Targeting Mitochondria

Objective:

To investigate the selective effect of Naja naja oxiana crude venom and its fractions on human colorectal cancer mitochondria to activate apoptosis signaling.

Methods:

Cells and mitochondria isolated from human cancerous and normal colorectal tissues exposed to N. oxiana crude venom and its fractions obtained from size-exclusion chromatography and then mitochondrial parameters related to up-stream cell death signalling such as reactive oxygen species formation, MMP, mitochondrial swelling, cytochrome c release and ATP content as mitochondrial parameters and activation of caspase3 and finally apoptosis/necrosis % were then assayed as cellular parameters.

Result:

Our findings indicated that crude venom (15, 30 and 60 µg/ml) and fraction 3; F3; (10, 20 and 40 µg/ml) of N. Oxiana venom induced a significant (p<0.05) increase of reactive oxygen species level, swelling of mitochondria, collapse of mitochondrial membrane potential (MMP), release of cytochrome c, activated caspase3 and decrease ATP content only in colon cancer tissue group but not from the healthy colon tissue group. Our results also showed that fraction 3 of venom decreased the percentage of viable cells and induced apoptosis in cancerous colorectal cells.

Conclusion:

F3 fraction of N. Oxiana venom is a suitable candidate for further studies as a new drug treatment of colorectal cancer due to its high capacity for induction of apoptosis signaling via mitochondrial pathway.

ZGDHu-1 promotes apoptosis of mantle cell lymphoma cells

Mantle cell lymphoma (MCL) is a well-defined aggressive Non-Hodgkin-lymphoma with short survival rates and remains incurable to date. Previously, we demonstrated the antitumor activity of ZGDHu-1(N, N'-di-(m-methylphenyi)-3, 6-dimethyl-1, 4-dihydro-1, 2, 4, 5-tetrazine-1, 4-dicarboamide) in chronic lymphocytic leukemia. In this study, ZGDHu-1 shows potent anti-lymphoma activity in MCL cells. ZGDHu-1 significantly induces cell cycle G2/M phase arrest and apoptosis in MCL cells. ZGDHu-1 reduces the protein levels of Mcl-1, Bcl-XL and cyclin D1. Importantly, ZGDHu-1 inhibits TNFα-induced IkBa phosphorylation, p65 nuclear translocation and NF-kB downstream target gene expression in MCL cells. MCL samples expressing high levels of Bcl-2 and high Bcl-2/Bax ratios tend to be less effective to ZGDHu-1. Together, these results suggest that ZGDHu-1 could inhibit the NF-kB signaling pathway partly, which may lead to the suppression of cell proliferation and the induction of apoptosis in MCL cells. Thus, our studies provide evidence of the potential of ZGDHu-1 in treating mantle cell lymphoma.

Induction of G2/M phase arrest and apoptosis by ZGDHU-1 in A549 and RERF-LC-MA lung cancer cells

Lung cancer is a major public health issue worldwide and is associated with high mortality and poor prognosis. Chemotherapy has the potential to reduce tumor size, increase operability and eradicate micrometastases; therefore, novel chemicals to treat lung cancer are urgently required. In the present study, the effects of N, N'-di-(m-methylphenyi)-3,6-dimethyl-1,4-dihydro-1,2,4, 5-tetrazine-1,4-dicarboamide (ZGDHu-1), a novel tetrazine derivative, were investigated in A549 and RERF-LC-MA lung cancer cells, and the underlying molecular mechanism of ZGDHu in treating lung cancer was determined. Following incubation with different concentrations of ZGDHu-1, flow cytometry analysis results indicated that ZGDHu-1 could induce G₂/mitotic (M) cell cycle arrest and apoptosis in A549 and RERF-LC-MA cells in a dose-dependent manner. Furthermore, western blot analysis demonstrated that the expression levels of G₂/M regulatory molecules, including cyclin B1, Cdc2 and cell division cycle 25c, decreased following treatment with ZGDHu-1, whilst p53 expression increased. In addition, A549 and RERF-LC-MA cell apoptosis was induced by cell cycle arrest at the G₂/M phase and through the downregulation of nuclear factor-κB. These results suggest that ZGDHu-1 may induce G₂/M phase arrest and apoptosis of lung cancer cells, and may serve as a potential therapeutic drug for the treatment of lung cancer.

Ellagic acid, a polyphenolic compound, selectively induces ROS-mediated apoptosis in cancerous B-lymphocytes of CLL patients by directly targeting mitochondria

To investigate the effects ofellagic acid (EA) on the cytotoxicity, B-lymphocytes isolated from CLL patients and healthy individuals. Flow cytometric assay was used to measure the percentage of apoptosis versus necrosis, intracellular active oxygen radicals (ROS), mitochondrial membrane potential (MMP) and the caspase-3 activity and then mitochondria were isolated from both groups B-lymphocytes and parameters of mitochondrial toxicity was investigated. Based on our results EA decreased the percentage of viable cells and induced apoptosis. EA increased ROS formation, mitochondria swelling, MMP decrease and cytochrome c release in mitochondria isolated from CLL BUT NOT healthy B-lymphocytes while pre-treatment with cyclosporine A and Butylated hydroxyl toluene (BHT) prevented these effects. Our results suggest that EA can act as an anti cancer candidate by directly and selectively targeting mitochondria could induce apoptosis through mitochondria pathway with increasing ROS production which finally ends in cytochrome c release, caspase 3 activation and apoptosis in cancerous B-lymphocytes isolated from CLL patients.

ZGDHu-1 and fludarabine have a synergistic effect on apoptosis of chronic lymphocytic leukemia cells

Previously, it was demonstrated that the novel proteasome inhibitor N,N'-di-(m-methylphenyi)-3,6-dimethyl-1,4-dihydro-1,2,4,5-tetrazine-1,4-dicarboamide (ZGDHu‑1) possesses activity against chronic lymphocytic leukemia (CLL). In the present study, we attempted to assess whether this drug has a synergistic effect with fludarabine on the apoptosis of CLL cells. Annexin V/PI staining, mitochondrial membrane potential (ΔΨm) and reactive oxygen species (ROS) levels were examined by flow cytometry in short-term cell culture of blood cells from untreated newly diagnosed patients ex vivo. Expression of active caspase-3 and the Bcl-2/Bax ratio for determination of apoptosis were also investigated by flow cytometry and western blot analysis. Our results revealed that the ZGDHu-1 may induce the apoptosis of CLL cells through the mitochondrial pathway and its pro-apoptotic effect is CLL-specific, not affecting normal lymphocytes. Most importantly, a combination of ZGDHu-1 and a non-cytotoxic dose of fludarabine had a synergistic apoptotic effect. To some extent, caspase-3 activation may be involved in the mechanism of the ZGDHu-1 synergistic cytotoxic effect with fludarabine, as well as the cleavage of PARP, consequently leading to apoptosis. Notably, the rate of apoptosis caused by ZGDHu-1 alone or in combination with fludarabine was independent of prognostic markers of CLL disease such as ZAP-70 and CD38 expression or clinical Rai classification stage. In conclusion, ZGDHu-1 exhibited a significant synergistic effect with fludarabine to induce the apoptosis of CLL cells, which implies a possible clinical application.

Relationship between in vitro drug sensitivity and clinical response of patients to treatment in chronic lymphocytic leukemia

To improve the efficacy of therapeutic options in chronic lymphocytic leukemia (CLL) an in vitro system to determine the response of mononuclear blood cells from blood of patients was elaborated. The study combines four approaches, i.e., cell viability, apoptosis rate, differential scanning calorimetry (DSC), and immunoblotting to develop personalized therapy protocols based on the cell sensitivity to drug exposure of individual CLL patients. The complementary analyses were performed on 28 peripheral blood samples from previously untreated CLL patients before therapy. The induction and progress of apoptosis in CLL cells exposed in vitro to purine analogs combined with mafosfamide, i.e., cladribine + mafosfamide (CM) and fludarabine + mafosfamide (FM) were assessed using the above approaches. The changes in thermal profiles (decrease/loss of transition at 95±5˚C) coincided with an accumulation of apoptotic cells, a decrease in the number of viable cells, and differences in the expression of the apoptosis‑related protein PARP‑1. No significant changes were observed in the thermal profiles of nuclei isolated from CLL cells resistant to the treatment. The complementary assays revealed a strong relationship between both the in vitro sensitivity of leukemia cells to drugs and the clinical response of the patients, determined usually after the sixth course of treatment (after ~6 months of therapy). As a summary of studies followed by complementary tests, our findings demonstrate the value of in vitro exposure of CLL cell samples to drugs intended to treat CLL patients, before their administration in order to recommend the most suitable and effective therapy for individual patients.