Apoptosis In Different Cancers Research Articles

Review Focusing on Molecular Mechanisms of Induction of Apoptosis in Different Cancers by a Flavone: Luteolin

Luteolin (3’,4’,5,7-tetrahydroxyflavone), an emerging anticancer flavone, has been reported to have other activities like antioxidant, antidiabetic, antimicrobial, anti-inflammatory, neuroprotective, cardioprotective and anti-allergic activities. In recent times, more attention has been paid to search the mechanism of apoptogenic effects of luteolin. Reports about the anticancer mechanism of luteolin published in Google Scholar, Scopus, Web of Science and PubMed are summarized in this study. Luteolin has shown potential against different cancers like breast, gastric, lung, hepatocellular, prostate etc. Mechanism of apoptosis in breast cancer cells is reported as inhibition of epidermal growth factor receptor-mediated pathway in MDA-MB 231 ER negative breast cancer cells by luteolin. Induction of apoptosis was linked with the inactivation of the critical kinases ERK and AKT in addition to P70S6K and mTOR in prostate cancer cells. Our literature survey shows that luteolin is a lead compound for anticancer chemotherapy. Further molecular mechanisms of induction of apoptosis should be explored in respect to luteolin in different cancer treatments.

TUNICAMYCIN-INDUCED ENDOPLASMIC RETICULUM STRESS UP-REGULATES TUMOUR-PROMOTING CYTOKINES IN ORAL SQUAMOUS CELL CARCINOMA

Objectives Signal transducer and activator of transcription (STAT)-3 lies at the convergence point of key pathways involved in many malignancies including oral squamous cell carcinoma (OSCC). Endoplasmic reticulum stress (ERS) and the unfolded protein response promote either survival or apoptosis in different cancers. We investigated the expression of STAT3 pathway-related genes and proteins under ERS in OSCC. Three normal oral keratinocyte (NOK) and three OSCC cell lines were subjected to tunicamycin to induce ERS for 24 hours or to the vehicle medium as control. A pathway-focussed array was used to analyse the modulation of STAT3 pathway gene expression under ERS using qPCR. The expression of key regulated proteins was investigated in the cell lines using immunocytochemistry and in 76 OSCC and 9 normal oral mucosa (NOM) tissue samples using tissue microarray technology and immunohistochemistry. Findings ERS resulted in up-regulation of interleukin-6 receptor (IL6R) gene in NOK cell lines (p = 0.001) and IL5 (p = 0.005) and IL22 (p = 0.024) in OSCC cell lines. Greater STAT3 (p = 0.019) and leukaemia inhibitory factor receptor (p = 0.042) protein expression was observed in treated than untreated NOK cell lines. Conclusions The gene and protein regulation patterns show that ERS plays a role in modifying the tumour microenvironment in OSCC by up-regulating tumour-promoting cytokines.

Natural Product Mediated Regulation of Death Receptors and Intracellular Machinery: Fresh from the Pipeline about TRAIL-Mediated Signaling and Natural TRAIL Sensitizers.

Rapidly developing resistance against different therapeutics is a major stumbling block in the standardization of therapy. Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-mediated signaling has emerged as one of the most highly and extensively studied signal transduction cascade that induces apoptosis in cancer cells. Rapidly emerging cutting-edge research has helped us to develop a better understanding of the signaling machinery involved in inducing apoptotic cell death. However, excitingly, cancer cells develop resistance against TRAIL-induced apoptosis through different modes. Loss of cell surface expression of TRAIL receptors and imbalance of stoichiometric ratios of pro- and anti-apoptotic proteins play instrumental roles in rewiring the machinery of cancer cells to develop resistance against TRAIL-based therapeutics. Natural products have shown excellent potential to restore apoptosis in TRAIL-resistant cancer cell lines and in mice xenografted with TRAIL-resistant cancer cells. Significantly refined information has previously been added and continues to enrich the existing pool of knowledge related to the natural-product-mediated upregulation of death receptors, rebalancing of pro- and anti-apoptotic proteins in different cancers. In this mini review, we will set spotlight on the most recently published high-impact research related to underlying mechanisms of TRAIL resistance and how these deregulations can be targeted by natural products to restore TRAIL-mediated apoptosis in different cancers.

Natural gypenosides: targeting cancer through different molecular pathways.

The second foremost cause of mortality around the word is cancer. Conventional therapies, such as radiation, surgery, and chemotherapy have limited accessibility owing to secondary resistance. Therefore, convenient, safe, and nonresistant drugs are urgently needed. Plant-derived natural products have attracted considerable interest owing to their high efficacy, low toxicity, and convenience. Gypenosides (Gyp) inhibit invasion, migration, metastasis, and proliferation and induce apoptosis in different cancers, including oral, lung, colorectal, hepatocellular, and leukemic cancers through different molecular pathways. This review summarizes Gyp studies on cancer to serve as a reference for further research and clinical trials.

Computationally designed high specificity inhibitors delineate the roles of BCL2 family proteins in cancer.

Many cancers overexpress one or more of the six human pro-survival BCL2 family proteins to evade apoptosis. To determine which BCL2 protein or proteins block apoptosis in different cancers, we computationally designed three-helix bundle protein inhibitors specific for each BCL2 pro-survival protein. Following in vitro optimization, each inhibitor binds its target with high picomolar to low nanomolar affinity and at least 300-fold specificity. Expression of the designed inhibitors in human cancer cell lines revealed unique dependencies on BCL2 proteins for survival which could not be inferred from other BCL2 profiling methods. Our results show that designed inhibitors can be generated for each member of a closely-knit protein family to probe the importance of specific protein-protein interactions in complex biological processes.

Apoptosis and molecular targeting therapy in cancer.

Apoptosis is the programmed cell death which maintains the healthy survival/death balance in metazoan cells. Defect in apoptosis can cause cancer or autoimmunity, while enhanced apoptosis may cause degenerative diseases. The apoptotic signals contribute into safeguarding the genomic integrity while defective apoptosis may promote carcinogenesis. The apoptotic signals are complicated and they are regulated at several levels. The signals of carcinogenesis modulate the central control points of the apoptotic pathways, including inhibitor of apoptosis (IAP) proteins and FLICE-inhibitory protein (c-FLIP). The tumor cells may use some of several molecular mechanisms to suppress apoptosis and acquire resistance to apoptotic agents, for example, by the expression of antiapoptotic proteins such as Bcl-2 or by the downregulation or mutation of proapoptotic proteins such as BAX. In this review, we provide the main regulatory molecules that govern the main basic mechanisms, extrinsic and intrinsic, of apoptosis in normal cells. We discuss how carcinogenesis could be developed via defective apoptotic pathways or their convergence. We listed some molecules which could be targeted to stimulate apoptosis in different cancers. Together, we briefly discuss the development of some promising cancer treatment strategies which target apoptotic inhibitors including Bcl-2 family proteins, IAPs, and c-FLIP for apoptosis induction.

Synergistic Effect of Resveratrol and Radiotherapy in Control of Cancers

Cancers will continue to be a threat to health unless they can be controlled by combinations of treatment modalities. In this review, evaluate the role of resveratrol (RSV) as a radiosensitizing agent was evaluated and underlying mechanisms holistically explored in different cancer models focusing on therapeutic possibilities. The ability of RSV to modify the effect of radiation exposure in normal and cancer cells has indeed been shown quite convincingly, the combination of RSV and IR exhibiting synergistic effects on different cancer cells. This is relevant since controlled exposure to IR is one of the most frequently applied treatments in cancer patients. However, radiotherapy (XRT) treatment regimes are very often not effective in clinical practice as observed in patients with glioma, prostate cancer (PCa), melanoma, for example, largely due to tumour radioresistant properties. Sensitization of IR-induced apoptosis by natural products such as RSV is likely to be relevant in cancer control and treatment. However, all cancers do not respond to RSV+IR in a similar manner. Therefore, for those such as the radioresistant PCa or melanoma cells, the RSV+IR regime has to be very carefully chosen in order to achieve effective and desirable outcomes with minimum toxicity to normal cells. They are reports that the highest concentration of 100 ?M RSV and highest dose of 5 Gy IR are sufficient to kill cells by induction of apoptosis, indicating that RSV is effective in radiosensitizing otherwise radioresistant cells. In general, it has been shown in different cancer cells that RSV+XRT effectively act by enhancing expression of anti-proliferative and pro-apoptotic molecules, and inhibiting pro-proliferative and anti-apoptotic molecules, leading to induction of apoptosis through various pathways, and cell death. If RSV+XRT can suppress the signature of cancer stemness, enhance the radiosensitivity by either targeting the mitochondrial functionality or modulating the tumour necrosis factor-mediated or Fas-FasL-mediated pathways of apoptosis in different cancers, particularly in vivo, its therapeutic use in the control of cancers holds promise in the near future.

Effect of the load versus capacity unbalance on the sensitivity of malignant pleural mesothelioma cells to proteasome inhibitors.

e18522 Background: Malignant Pleural Mesothelioma (MPM) is an aggressive cancer that originates from the mesothelium of the pleural cavities. Due to its resistance to all chemotherapies available, news therapies against MPM are urgently needed. Bortezomib is a potent Proteasome Inhibitors (PI) that induces apoptosis in different cancers and it was recently approved for treatment of Multiple Myeloma (MM). Since in MM an unbalance between a reduced proteasomal activity (capacity) and an increased proteins degradation (load) was shown to determine apoptotic sensitivity to PI, we challenged this paradigm also in MPM. Methods: Four different MPM (MM98, REN, MMB, MSTO) and a normal (TERT) pleural lines were treated with increasing doses (from 1 to 1000 nM) of Bortezomib and after 24h apoptosis was assessed by flow cytometric analysis of AnnexinV and propidium iodide positive cells. Levels of polyubiquitinated proteins were evaluated by immunofluorescence microscopy and western blotting with the specific monoclonal Ab Fk2 (BIOMOL International). The three main proteasome activities were measured in continuoin cellular extracts at 37°C with a Carry Eclipse spectrofluorometer (Varian, Palo Alto) by means of specific fluorogenic substrates (Suc-LLVY-amc, Bz-VGR-amc, Suc-YVAD-amc). Results: The sensitivity towards Bortezomib greatly differs between the 5 pleural lines analyzed. Specifically the EC50value was higher for the TERT line (130 nM) while for MPM lines ranged between 17 nM (MM98) and 71 nM (MSTO). Importantly, for all the 5 lines analyzed enhanced sensitivity to Bortezomib perfectly correlates with increased levels of ubiquitinated proteins and reduced proteasome specific activity. Conclusions: Our results prove that MPM lines are significantly more sensitive towards the pro-apoptotic effect of Bortezomib than normal pleural cells. Moreover, as in MM, also in MPM PI-sensitivity stems from an unbalance of the load/capacity ratio. Our data, therefore, establish a rationale for the use of Bortezomib (and new second generation PI) in MPM and indicate that combinatorial therapies with other drugs active on the proteostasis network (like HSP inhibitors) might be highly effective against this cancer.

Abstract 4157: A role for miR-137 in enhancing efficacy of delphinidin in human glioblastoma.

Abstract Glioblastoma is the most lethal brain cancer in humans. Heterogeneity of cells in glioblastoma makes it extremely hard to control this tumor with a single therapeutic agent. Combination of therapeutic agents with diverse anti-cancer mechanisms must be used to manage this malignancy. Failures of conventional therapies and systemic toxicity have forced the search for newer agents, which may inhibit glioblastoma with less or no toxicity. Recently, microRNAs (miRs) are emerging as important regulators of different cellular processes such as proliferation, differentiation, and apoptosis in different cancers. Recent studies also suggest that the tumor suppressor miR-137 (TS miR-137) can induce differentiation and cell cycle arrest in human glioblastoma stem cells. In colorectal cancer, miR-137 is frequently silenced due to promoter hypermethylation. Use of 5-aza-2′-deoxycytidine (AzaC), an inhibitor of DNA methylation, may increase expression of miR-137 in glioblastoma with significant inhibition of proliferation of tumor cells. Delphinidin (DPN), which belongs to a class of natural chemicals from colored fruits, has been shown to inhibit cell growth and induce apoptosis in many different cancers. We hypothesized that combination therapy with miR-137 overexpression and DPN treatment in presence of AzaC could be an effective therapeutic strategy to control growth of glioblastoma. We used MTT assay to examine the doses (10 to 50 μM) of DPN for inhibition of cell proliferation in three glioblastoma cell lines (U87MG, T98G, and LN18). All cell lines demonstrated 50% inhibition of proliferation at 50 μM DPN. We performed Annexin V staining and flow cytometric analysis after treatment with AzaC, transfection of precursor miR-137 mimic, and treatment with DPN alone and in combination in all three glioblastoma cell lines. Overexpression of only miR-137 could induce apoptosis, which was dramatically increased when the cells were subjected to combination therapy with DPN in presence of AzaC. Then, we examined efficacy of combination of AzaC, miR-137, and DPN for inhibition of angiogenic network formation and invasion properties in all three glioblastoma cell lines. Co-culture of human microvascular endothelial (HMVE) cells with control U87MG, T98G, or LN18 cells prompted HMVE cells for capillary-like network formation, which was completely inhibited during co-culture of HMVE cells and glioblastoma cells treated with combination therapy. Following combination therapy, we observed suppression of expression of angiogenic factors (VEGF and b-FGF), growth factor receptor (EGFR), and invasive factors (MMP-2 and MMP-9) and also inhibition of Akt and NF-κB survival pathways in all three glioblastoma cell lines. So, combination of the methylation inhibitor AzaC, overexpression of the TS miR-137, and the relatively new flavonoid DPN could be a promising therapeutic strategy for inhibiting growth of different human glioblastoma cells. Citation Format: Mrinmay Chakrabarti, Naren L. Banik, Swapan K. Ray. A role for miR-137 in enhancing efficacy of delphinidin in human glioblastoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4157. doi:10.1158/1538-7445.AM2013-4157

Targeting microRNAs to modulate TRAIL-induced apoptosis of cancer cells

MicroRNAs (miRNAs) are endogenously expressed small non-coding RNAs, which are evolutionarily conserved and function as regulators of gene expression. These molecules are involved in numerous biological processes including differentiation, development, proliferation and apoptosis. Further investigation identifies that miRNAs may act as either potent oncogenes or tumor-suppressor genes, linking to cancer initiation and progression. Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), as a member of the TNF family, is an attractive therapeutic target in cancer because it directly induces tumor cell apoptosis and has no cytotoxicity to normal cell types in vitro or in vivo. However, the resistance to TRAIL-induced apoptosis limits its clinical effectiveness. Interestingly, several studies convincingly demonstrate a role of miRNAs in modulating sensitive/resistant phenotypes to TRAIL. Here, we review the current findings about miRNAs involved in TRAIL-induced apoptosis in different cancers.

Retroviral immunotoxin gene therapy of leukemia in mice using leukemia-specific T cells transduced with an interleukin-3/Bax fusion protein gene.

In past studies, we showed that T cells transduced with retroviral diphtheria immunotoxin (IT) target genes could serve as vehicles for delivering IT to tumors in vivo. We took advantage of the observation that antigen-specific T cells are able to penetrate tumors to design an approach delivering combined cellular and humoral therapy directly to the tumor site. To improve tumor specificity, we selected interleukin (IL)-3 as a ligand because its receptor is selectively overexpressed on myeloid leukemia progenitors. Because Bcl-2 family proteins show structural similarity to diphtheria toxin (DT), we constructed a unique retroviral IT using Bax, a proapoptotic member of the Bcl-2 family, in place of DT. Bax was chosen because several studies showed that its transduction induces lethal apoptosis in different cancers. The retroviral construct for gene therapy included IL-3 positioned downstream of its 80 amino acid leader, and permitted cotranslational protein synthesis of hybrid IL-3/human Bax fusion protein. Other vectors were constructed with IL-3 fused to DT or Pseudomonas exotoxin. Retroviral vectors were used to transiently transduce C8, a CD4(+) T cell clone that specifically recognized FBL-3, a lethal myeloid leukemia. Supernatants collected from transduced cells showed proapoptotic activity and selectively inhibited FBL-3 cells in vitro. Intraperitoneal injection of transduced but not nontransduced C8 into mice with subcutaneous tumors or systemic cancer significantly inhibited tumor growth. These results indicate that retroviral IT made with IL-3 and various toxic proteins may be useful in patients with acute myelogenous leukemia (AML). Furthermore, the Bax construct may be particularly useful as a nonimmunogenic substitute for bacterial toxins in retIT.