Faisal F. Radwan

A possible cross-talk between autophagy and apoptosis in generating an immune response in melanoma

Melanoma is the most aggressive form of skin cancer, responsible for the majority of skin cancer related deaths. Thus, the search for natural molecules which can effectively destroy tumors while promoting immune activation is essential for designing novel therapies against metastatic melanoma. Here, we report for the first time that a natural triterpenoid, Ganoderic acid DM (GA-DM), induces an orchestrated autophagic and apoptotic cell death, as well as enhanced immunological responses via increased HLA class II presentation in melanoma cells. Annexin V staining and flow cytometry showed that GA-DM treatment induced apoptosis of melanoma cells, which was supported by a detection of increased Bax proteins, co-localization and elevation of Apaf-1 and cytochrome c, and a subsequent cleavage of caspases 9 and 3. Furthermore, GA-DM treatment initiated a possible cross-talk between autophagy and apoptosis as evidenced by increased levels of Beclin-1 and LC3 proteins, and their timely interplay with apoptotic and/or anti-apoptotic molecules in melanoma cells. Despite GA-DM’s moderate cytotoxicity, viable cells expressed high levels of HLA class II proteins with improved antigen presentation and CD4+ T cell recognition. The antitumor efficacy of GA-DM was also investigated in vivo in murine B16 melanoma model, where GA-DM treatment slowed tumor formation with a significant reduction in tumor volume. Taken together, these findings demonstrate the potential of GA-DM as a natural chemo-immunotherapeutic capable of inducing a possible cross-talk between autophagy and apoptosis, as well as improved immune recognition for sustained melanoma tumor clearance.

Reduction of myeloid-derived suppressor cells and lymphoma growth by a natural triterpenoid.

Lymphoma is a potentially life threatening disease. The goal of this study was to investigate the therapeutic potential of a natural triterpenoid, Ganoderic acid A (GA‐A) in controlling lymphoma growth both in vitro and in vivo. Here, we show that GA‐A treatment induces caspase‐dependent apoptotic cell death characterized by a dose‐dependent increase in active caspases 9 and 3, up‐regulation of pro‐apoptotic BIM and BAX proteins, and a subsequent loss of mitochondrial membrane potential with release of cytochrome c. In addition to GA‐As anti‐growth activity, we show that lower doses of GA‐A enhance HLA class II‐mediated antigen (Ag) presentation and CD4+ T cell recognition of lymphoma cells in vitro. The therapeutic relevance of GA‐A treatment was also tested in vivo using the EL4 syngeneic mouse model of metastatic lymphoma. GA‐A‐treatment significantly prolonged survival of EL4 challenged mice and decreased tumor metastasis to the liver, an outcome accompanied by a marked down‐regulation of STAT3 phosphorylation, reduction myeloid‐derived suppressor cells (MDSCs), and enhancement of cytotoxic CD8+ T cells in the host. Thus, GA‐A not only selectively induces apoptosis in lymphoma cells, but also enhances cell‐mediated immune responses by attenuating MDSCs, and elevating Ag presentation and T cell recognition. The demonstrated therapeutic benefit indicates that GA‐A is a candidate for future drug design for the treatment of lymphoma. J. Cell. Biochem. 116: 102–114, 2015.

Mechanisms regulating enhanced human leukocyte antigen class II-mediated CD4 + T cell recognition of human B-cell lymphoma by resveratrol

Abstract Malignant B-cells express measurable levels of human leukocyte antigen (HLA) class II proteins, but often escape immune recognition by CD4 + T cells. Resveratrol (Resv) has been the focus of numerous investigations due to its potential chemopreventive and anti-cancer effects, but it has never been tested in the regulation of immune components in B-cell tumors. Here, we show for the first time that Resv treatment enhances HLA class II-mediated immune detection of B-cell lymphomas by altering immune components and class II presentation in tumor cells. Resv treatment induced an up-regulation of both classical and non-classical HLA class II proteins (DR and DM) in B-lymphoma cells. Resv also altered endolysosomal cathepsins (Cat S, B and D) and a thiol reductase (GILT), increasing HLA class II-mediated antigen (Ag) processing in B-cell lymphomas and their subsequent recognition by CD4 + T cells. Mechanistic study demonstrated that Resv treatment activated the recycling class II pathway of Ag presentation through up-regulation of Rab 4B protein expression in B-lymphoma cells. These findings suggest that HLA class II-mediated immune recognition of malignant B-cells can be improved by Resv treatment, thus encouraging its potential use in chemoimmunotherapy of B-cell lymphoma.

Immunoglobulin Genes Influence the Magnitude of Humoral Immunity to Cytomegalovirus Glycoprotein B

Human cytomegalovirus (HCMV) is a risk factor for many human diseases, but among exposed individuals, not everyone is equally likely to develop HCMV-spurred diseases, implying the presence of host genetic factors that might modulate immunity to this virus. Here, we show that antibody responsiveness to HCMV glycoprotein B (gB) is significantly associated with particular immunoglobulin GM (γ marker) genotypes. Anti-HCMV gB antibody levels were highest in GM 17/17 homozygotes, intermediate in GM 3/17 heterozygotes, and lowest in GM 3/3 homozygotes (28.2, 19.0, and 8.1 µg/mL, respectively; P=.014). These findings provide mechanistic insights in the etiopathogenesis of HCMV-spurred diseases.

Ganoderic Acid DM: An Alternative Agent for the Treatment of Advanced Prostate Cancer

Prostate cancer is the most commonly diagnosed cancer in men and accounts for significant morbidity and mortality in the western world. While traditional therapies are effective at clearing early stage cancer, they often fail to treat late stage metastatic disease. Thus, an effective therapy that targets prostate tumor growth and metastasis is desired for alleviating the disease and improving patient outcomes. Natural extracts have been the focus of recent investigation, particularly those with reduced cellular toxicity to healthy tissue. In this review, we discuss one potential candidate, ganoderic acid, an extract from the Ganoderma lucidum mushroom that has been tested in multiple cancer models. Interestingly, ganoderic acid DM (GA-DM) has shown toxicity to both androgen-dependent and independent prostate cancer cells with reduced osteoclastogenesis in late stage metastatic disease. This review will discuss the current knowledge on this GA-DM extract and the potential benefit in treating advanced prostate cancer. We will also provide an overview on the targeted delivery of GA-DM through nanoparticles that would reduce bystander toxicity and improve the drugs effectiveness. An improved understanding of this drug and its uses will advance the field of natural chemotherapeutics, particularly in treating advanced prostate cancer.

The decoy Fcγ receptor encoded by the cytomegalovirus UL119-UL118 gene has differential affinity to IgG proteins expressing different GM allotypes.

Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus that has been implicated in many diseases. However, there is significant divergence between HCMV seroprevalence and the prevalence of HCMV-associated diseases, implying the presence of host genetic factors that might modulate immunity to this virus. HCMV deploys many sophisticated strategies to evade host immunosurveillance. One strategy involves encoding for proteins that have functional properties of the Fcγ receptor (FcγR). The aim of the present investigation was to determine whether the UL119-UL118-encoded recombinant FcγR ectodomain binds differentially to genetically disparate IgG1 proteins. Results show that mean absorbance values for binding of HCMV UL119-UL118-encoded Fcγ receptor to the immunoglobulin GM (γ marker) 1,17-expressing IgG1 were significantly higher than to the IgG1 expressing the allelic GM 3 allotype (0.225 vs. 0.151; p=0.039). These findings suggest possible mechanisms underlying the maintenance of immunoglobulin GM gene polymorphism and its putative role in the etiology of HCMV-associated diseases.

HLA class II defects in Burkitt lymphoma: bryostatin-1-induced 17 kDa protein restores CD4+ T-cell recognition.

While the defects in HLA class I-mediated Ag presentation by Burkitt lymphoma (BL) have been well documented, CD4+ T-cells are also poorly stimulated by HLA class II Ag presentation, and the reasons underlying this defect(s) have not yet been fully resolved. Here, we show that BL cells are deficient in their ability to optimally stimulate CD4+ T cells via the HLA class II pathway. The observed defect was not associated with low levels of BL-expressed costimulatory molecules, as addition of external co-stimulation failed to result in BL-mediated CD4+ T-cell activation. We further demonstrate that BL cells express the components of the class II pathway, and the defect was not caused by faulty Ag/class II interaction, because antigenic peptides bound with measurable affinity to BL-associated class II molecules. Treatment of BL with broystatin-1, a potent modulator of protein kinase C, led to significant improvement of functional class II Ag presentation in BL. The restoration of immune recognition appeared to be linked with an increased expression of a 17 kDa peptidylprolyl-like protein. These results demonstrate the presence of a specific defect in HLA class II-mediated Ag presentation in BL and reveal that treatment with bryostatin-1 could lead to enhanced immunogenicity.

Endogenous antibody responsiveness to epidermal growth factor receptor is associated with immunoglobulin allotypes and overall survival of patients with glioblastoma

BACKGROUND Immunoglobulin γ marker (GM) and κ marker (KM) allotypes, hereditary antigenic determinants of γ and κ chains, respectively, have been shown to be associated with immunity to a variety of self and nonself antigens, but their possible contribution to immunity to the tumor-associated antigens epidermal growth factor receptor (EGFR) and EGFR variant (v)III has not been evaluated. The aim of the present investigation was to determine whether the interindividual variation in endogenous antibody responsiveness to EGFR and EGFRvIII is associated with particular GM, KM, and Fcγ receptor (FcγR) genotypes and whether antibody levels were associated with the overall survival of patients with glioblastoma. METHODS A total of 126 Caucasian participants with glioblastoma were genotyped for several GM, KM, and FcγR alleles and characterized for IgG antibodies to EGFR and EGFRvIII antigens. RESULTS The anti-EGFR antibody levels associated with GM 3/3 homozygotes and GM 3/17 heterozygotes were similar (15.9 vs 16.4 arbitrary units [AU]/µL) and significantly lower than those associated with GM 17/17 homozygotes (19.6 AU/µL; nominal P = .007). Participants homozygous for the GM 21 allele also had significantly higher levels of anti-EGFR antibodies than GM 5/5 homozygotes and GM 5/21 heterozygotes (20.1 vs 16.0 and 16.3 AU/µL; nominal P = .005). Similar associations were found with immune responsiveness to EGFRvIII. Higher anti-EGFR and anti-EGFRvIII antibody levels were associated with enhanced overall survival (16 vs 11 mo, nominal P = .038 and 20 vs 11 mo, nominal P = .004, respectively). CONCLUSIONS GM allotypes contribute to humoral immunity to EGFR in glioblastoma.

Autophagy-dependent crosstalk between GILT and PAX-3 influences radiation sensitivity of human melanoma cells

Melanoma represents an ever‐increasing problem in the western world as incidence rates continue to climb. Though manageable during early stages, late stage metastatic disease is highly resistant to current intervention. We have previously shown that gamma‐interferon‐inducible lysosomal thiol‐reductase (GILT) enhances HLA class II antigen processing and immune detection of human melanoma cells. Here we report that GILT expression inhibits a potential target, paired box‐3 (PAX‐3) protein, in late stage human metastatic melanoma. We also show that GILT transfection or induction by IFN‐γ, decreases PAX‐3 protein expression while upregulating the expression of Daxx, which is also a repressor of PAX‐3. Confocal microscopic analysis demonstrated that GILT co‐localizes with PAX‐3 protein, but not with Daxx within melanoma cells. Immunoprecipitation and immunoblotting studies suggest that GILT expression negatively regulates PAX‐3 through the autophagy pathway, potentially resulting in increased susceptibility to conventional treatment in the form of chemotherapy or radiotherapy. While high‐dose radiation is a common treatment for melanoma patients, our data suggest that GILT expression significantly increased the susceptibility of melanoma cells to low‐dose radiation therapy via upregulation of tumor suppressor protein p53. Overall, these data suggest that GILT has multiple roles in inducing human melanoma cells as better targets for radiation and immunotherapy.

Abstract 1653: Regulation of autophagy and apoptosis by a natural triterpenoid in diffuse large B-cell lymphoma.

Diffuse large B-cell lymphoma (DLBCL), a subtype of non-Hodgkin9s lymphoma, is the most common lymphoid malignancy in the western world. Treatment of DLBCL has been greatly improved in recent years with the addition of the monoclonal antibody Rituximab to the gold standard CHOP chemotherapy regimen, but these treatments are often ineffective in patients with highly aggressive disease or in patients of advanced age. A real problem given the population of DLBCL patients is largely 60 years of age or older, these chemotherapeutics also present the issue of severe toxicity to the patient(s). Thus, studies have focused lately on natural products that can selectively kill malignant lymphomas while displaying a reduced host toxicity profile. Here, we report that a natural extract from the Ganoderma lucidum mushroom, GA-DM, induces apoptosis in human DLBCL cell lines and primary tumors, and activates an orchestrated autophagy/apoptosis pathway in the murine B-cell lymphoma cell line A20. Antitumor efficacy of GA-DM was also investigated in vivo in a murine B-cell lymphoma model using the A20 cell line, where GA-DM (50mg/kg) treatment reduced both the number of tumor metastases and the overall tumor burden in diseased mice. These findings support the potential use of GA-DM as a novel chemotherapeutic in the treatment of DLBCL and could improve the treatment of higher risk patients with advanced disease who can9t tolerate current chemotherapy treatment. Citation Format: Bently Doonan, Azim Hossain, Faisal Radwan, Azizul Haque. Regulation of autophagy and apoptosis by a natural triterpenoid in diffuse large B-cell lymphoma. [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 1653. doi:10.1158/1538-7445.AM2013-1653