Cancer prevention and therapy through the modulation of transcription factors by bioactive natural compounds.

The association between chronic inflammation and cancer development has been well documented. One of the major obstacles in cancer treatment is the persistent autocrine and paracrine activation of pro-inflammatory transcription factors such as nuclear factor-κB, signal transducer and activator of transcription 3, activator protein 1, fork head box protein M1, and hypoxia-inducible factor 1α in a wide variety of tumor cell lines and patient specimens. This, in turn, leads to an accelerated production of cellular adhesion molecules, inflammatory cytokines, chemokines, anti-apoptotic molecules, and inducible nitric oxide synthase. Numerous medicinal plant-derived compounds have made a tremendous impact in drug discovery research endeavors, and have been reported to modulate the activation of diverse oncogenic transcription factors in various tumor models. Moreover, novel therapeutic combinations of standard chemotherapeutic drugs with these agents have significantly improved patient survival by making cancer cells more susceptible to chemotherapy and radiotherapy. In this review, we critically analyze the existing literature on the modulation of diverse transcription factors by various natural compounds and provide views on new directions for accelerating the discovery of novel drug candidates derived from Mother Nature.

Macrophage IL-1ß contributes to tumorigenesis through paracrine AIM2 inflammasome activation in the tumor microenvironment.

Intracellular recognition of self and non-self -nucleic acids can result in the initiation of effective pro-inflammatory and anti-tumorigenic responses. We hypothesized that macrophages can be activated by tumor-derived nucleic acids to induce inflammasome activation in the tumor microenvironment. We show that tumor conditioned media (CM) can induce IL-1ß production, indicative of inflammasome activation in primed macrophages. This could be partially dependent on caspase 1/11, AIM2 and NLRP3. IL-1ß enhances tumor cell proliferation, migration and invasion while coculture of tumor cells with macrophages enhances the proliferation of tumor cells, which is AIM2 and caspase 1/11 dependent. Furthermore, we have identified that DNA-RNA hybrids could be the nucleic acid form which activates AIM2 inflammasome at a higher sensitivity as compared to dsDNA. Taken together, the tumor-secretome stimulates an innate immune pathway in macrophages which promotes paracrine cancer growth and may be a key tumorigenic pathway in cancer. Broader understanding on the mechanisms of nucleic acid recognition and interaction with innate immune signaling pathway will help us to better appreciate its potential application in diagnostic and therapeutic benefit in cancer.

Rationally targeted anti-VISTA antibody that blockades the C-C' loop region can reverse VISTA immune suppression and remodel the immune microenvironment to potently inhibit tumor growth in an Fc independent manner.

BACKGROUND: Despite significant progress in cancer immunotherapy in recent years, resistance to existing immune checkpoint therapies (ICT) is common. V-domain Ig suppressor of T cell activation (VISTA), a predominantly myeloid immune checkpoint regulator, represents a promising therapeutic target due to its role in suppressing proinflammatory antitumor responses in myeloid-enriched tumor microenvironments. However, uncertainty around the cognate VISTA ligand has made the development of effective anti-VISTA antibodies challenging. The expression of VISTA on normal immune cell subtypes argues for a neutralizing non-depleting antibody, however, previous reported anti-VISTA antibodies use IgG1 Fc isotypes that deplete VISTA+ cells by antibody dependent cellular cytotoxicity/complement dependent cytotoxicity and these antibodies have shown fast serum clearance and immune toxicities. METHOD: Here we used a rational antibody discovery approach to develop the first Fc-independent anti-VISTA antibody, HMBD-002, that binds a computationally predicted functional epitope within the C-C-loop, distinct from other known anti-VISTA antibodies. This epitope is species-conserved allowing robust in vitro and in vivo testing of HMBD-002 in human and murine models of immune activation and cancer including humanized mouse models. RESULTS: We demonstrate here that blockade by HMBD-002 inhibits VISTA binding to potential partners, including V-Set and Immunoglobulin domain containing 3, to reduce myeloid-derived suppression of T cell activity and prevent neutrophil migration. Analysis of immune cell milieu suggests that HMBD-002 treatment stimulates a proinflammatory phenotype characterized by a Th1/Th17 response, recapitulating a phenotype previously noted in VISTA knockout models. This mechanism of action is further supported by immune-competent syngenic and humanized mouse models of colorectal, breast and lung cancer where neutralizing VISTA, without depleting VISTA expressing cells, significantly inhibited tumor growth while decreasing infiltration of suppressive myeloid cells and increasing T cell activity. Finally, we did not observe either the fast serum clearance or immune toxicities that have been reported for IgG1 antibodies. CONCLUSION: In conclusion, we have shown that VISTA-induced immune suppression can be reversed by blockade of the functional C-C' loop region of VISTA with a first-in-class rationally targeted and non-depleting IgG4 isotype anti-VISTA antibody, HMBD-002. This antibody represents a highly promising novel therapy in the VISTA-suppressed ICT non-responder population.

Triple negative breast cancer in Asia: An insider's view.

While tremendous improvement has been made for the treatment of breast cancers, the treatment of triple negative breast cancer (TNBC) still remains a challenge due to its aggressive characteristics and limited treatment options. Most of the studies on TNBC were conducted in Western population and TNBC is reported to be more frequent in the African women. This review encapsulates the studies conducted on TNBC patients in Asian population and elucidates the similarities and differences between these two regions. The current treatment of TNBC includes surgery, radiotherapy and chemotherapy. In addition to the current chemotherapies, which mainly include cytotoxic agents, such as taxanes and anthracyclines, many clinical trials are investigating the potential use of other chemotherapy drugs, targeted therapeutics and combinational therapies to treat TNBC. Moreover, this review also integrates the studies involving novel markers, which will help us to dissect the pathologic process of TNBC and in turn facilitate the development of better treatment strategies to combat TNBC.

Annexin-A1 enhances breast cancer growth and migration by promoting alternative macrophage polarization in the tumour microenvironment.

Macrophages are potent immune cells with well-established roles in the response to stress, injury, infection and inflammation. The classically activated macrophages (M1) are induced by lipopolysaccharide (LPS) and express a wide range of pro-inflammatory genes. M2 macrophages are induced by T helper type 2 cytokines such as interleukin-4 (IL4) and express high levels of anti-inflammatory and tissue repair genes. The strong association between macrophages and tumour cells as well as the high incidences of leukocyte infiltration in solid tumours have contributed to the discovery that tumour-associated macrophages (TAMs) are key to tumour progression. Here, we investigated the role of Annexin A1 (ANXA1), a well characterized immunomodulatory protein on macrophage polarization and the interaction between macrophages and breast cancer cells. Our results demonstrate that ANXA1 regulates macrophage polarization and activation. ANXA1 can act dually as an endogenous signalling molecule or as a secreted mediator which acts via its receptor, FPR2, to promote macrophage polarization. Furthermore, ANXA1 deficient mice exhibit reduced tumour growth and enhanced survival in vivo, possibly due to increased M1 macrophages within the tumor microenvironment. These results provide new insights into the molecular mechanisms of macrophage polarization with therapeutic potential to suppress breast cancer growth and metastasis.

PPARγ Ligand-induced Annexin A1 Expression Determines Chemotherapy Response via Deubiquitination of Death Domain Kinase RIP in Triple-negative Breast Cancers.

Metastatic breast cancer is still incurable so far; new specifically targeted and more effective therapies for triple-negative breast cancer (TNBC) are required in the clinic. In this study, our clinical data have established that basal and claudin-low subtypes of breast cancer (TNBC types) express significantly higher levels of Annexin A1 (ANXA1) with poor survival outcomes. Using human cancer cell lines that model the TNBC subtype, we observed a strong positive correlation between expression of ANXA1 and PPARγ. A similar correlation between these two markers was also established in our clinical breast cancer patients' specimens. To establish a link between these two markers in TNBC, we show de novo expression of ANXA1 is induced by activation of PPARγ both in vitro and in vivo and it has a predictive value in determining chemosensitivity to PPARγ ligands. Mechanistically, we show for the first time PPARγ-induced ANXA1 protein directly interacts with receptor interacting protein-1 (RIP1), promoting its deubiquitination and thereby activating the caspase-8-dependent death pathway. We further identified this underlying mechanism also involved a PPARγ-induced ANXA1-dependent autoubiquitination of cIAP1, the direct E3 ligase of RIP1, shifting cIAP1 toward proteosomal degradation. Collectively, our study provides first insight for the suitability of using drug-induced expression of ANXA1 as a new player in RIP1-induced death machinery in TNBCs, presenting itself both as an inclusion criterion for patient selection and surrogate marker for drug response in future PPARγ chemotherapy trials. Mol Cancer Ther; 16(11); 2528-42. ©2017 AACR.

Novel aromatase inhibitors selection using induced fit docking and extra precision methods: Potential clinical use in ER-alpha-positive breast cancer.

Aromatase (CYP19A1) the key enzyme of estrogen biosynthesis, is often deregulated in breast cancer patients. It catalyzes the conversion of androgen to estrogen, thus responsible for production of estrogen in human body. However, it causes over-production of estrogen which eventually leads to proliferation of breast cancer cells. Identification of new small molecule inhibitors targeted against CYP19A1 therefore, facilitates to increase drug sensitivity of cancer cells. In this scenario, the present study aims to identify new molecules which could block or suppress the activity of aromatase enzyme by molecular docking studies using Schrödinger-Maestro v9.3. In this study we used in silico approach by modeling CYP19A1 protein the strcture was subjected to protein preparation wizard; to add hydrogen and optimize the protonation states of Thr310 and Ser478 and Asp309 residues. Active site of the CYP19A1 protein was identified using SiteMap tool of Scchrodinger package. We further carried out docking studies by means of Glid, with various ligands. Based on glid score, potential ligands were screeened and their interaction with CYP19A1 was identified. The best hits were further screened for Lipinski's rule for drug-likeliness and bioactivity scoring properties. Thus, we report two rubivivaxin and rhodethrin compounds that have successfully satisfied all in silico parameters, necessitating further in vitro and in vivo studies.

Targeting the PI3K/Akt signaling pathway in gastric carcinoma: A reality for personalized medicine?

Frequent activation of phosphatidylinositol-3 kinases (PI3K)/Akt/mTOR signaling pathway in gastric cancer (GC) is gaining immense popularity with identification of mutations and/or amplifications of PIK3CA gene or loss of function of PTEN, a tumor suppressor protein, to name a few; both playing a crucial role in regulating this pathway. These aberrations result in dysregulation of this pathway eventually leading to gastric oncogenesis, hence, there is a need for targeted therapy for more effective anticancer treatment. Several inhibitors are currently in either preclinical or clinical stages for treatment of solid tumors like GC. With so many inhibitors under development, further studies on predictive biomarkers are needed to measure the specificity of any therapeutic intervention. Herein, we review the common dysregulation of PI3K/Akt/mTOR pathway in GC and the various types of single or dual pathway inhibitors under development that might have a superior role in GC treatment. We also summarize the recent developments in identification of predictive biomarkers and propose use of predictive biomarkers to facilitate more personalized cancer therapy with effective PI3K/Akt/mTOR pathway inhibition.