Cyclophosphamide enhances the antitumor potency of GITR engagement by increasing oligoclonal cytotoxic T cell fitness

Only a subset of cancer patients responds to checkpoint blockade inhibition in the clinic. Strategies to overcome resistance are promising areas of investigation. Targeting glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) has shown efficacy in preclinical models, but GITR engagement is ineffective in controlling advanced, poorly immunogenic tumors, such as B16 melanoma, and has not yielded benefit in clinical trials. The alkylating agent cyclophosphamide (CTX) depletes regulatory T cells (Tregs), expands tumor-specific effector T cells (Teffs) via homeostatic proliferation, and induces immunogenic cell death. GITR agonism has an inhibitory effect on Tregs and activates Teffs. We therefore hypothesized that CTX and GITR agonism would promote effective antitumor immunity. Here we show that the combination of CTX and GITR agonism controlled tumor growth in clinically relevant mouse models. Mechanistically, we show that the combination therapy caused tumor cell death, clonal expansion of highly active CD8+ T cells, and depletion of Tregs by activation-induced cell death. Control of tumor growth was associated with the presence of an expanded population of highly activated, tumor-infiltrating, oligoclonal CD8+ T cells that led to a diminished TCR repertoire. Our studies show that the combination of CTX and GITR agonism is a rational chemoimmunotherapeutic approach that warrants further clinical investigation.

CTLA-4 blockade drives loss of Treg stability in glycolysis-low tumours

Limiting the metabolic competition in the tumor microenvironment (TME) may increase the effectiveness of immunotherapy. Because of its critical role in glucose metabolism of activated T cells, CD28 signaling has been proposed as a T-cell metabolic biosensor¹. Conversely, CTLA-4 engagement has been shown to down-regulate T-cell glycolysis¹. Here, we investigated the impact of CTLA-4 blockade on the metabolic fitness of intra-tumor T cells in relationship to the tumor glycolytic capacity. We found that CTLA-4 blockade promotes immune cell infiltration and metabolic fitness especially in glycolysis-low tumors. Accordingly, anti-CTLA-4 achieved better therapeutic outcomes in mice bearing glycolysis-defective tumors. Intriguingly, tumor-specific CD8⁺ T-cell responses correlated with phenotypic and functional destabilization of tumor-infiltrating regulatory T cells (Tregs) toward IFN-γ- and TNF-α-producing cells in glycolysis-defective tumors. By mimicking the highly and poorly glycolytic TME in vitro, we show that the effect of CTLA-4 blockade to promote Treg destabilization is dependent on Treg glycolysis and CD28 signaling. These findings indicate that decreasing tumor competition for glucose may facilitate the therapeutic activity of CTLA-4 blockade, thus supporting its combination with inhibitors of tumor glycolysis. Moreover, these results reveal a new mechanism through which anti-CTLA-4 interferes with Treg function in the presence of glucose.

Abstract 3562: Exosomes secreted by AC133+/CD34+cells harbor invasion potentiating miRNAs

Despite the exciting progresses in the treatment of breast cancer, the effectiveness of the current therapeutic modalities is still restricted by drug toxicity, resistance, and lack of predictive and prognostic biomarkers. Breast cancer continues to be the second leading cause of cancer death among women in the U.S. Therefore, the development of new therapeutic targets and further understanding of the tumor microenvironment is extremely critical for accelerating the progress against breast cancer. Human AC133+/CD34+ stem cells are a highly promising and novel therapeutic option for targeting tumor angiogenesis. We and others have described the incorporation of bone marrow derived AC133+/CD34+/KDR+ cells in the neovasculature around implanted tumors supporting their growth and metastasis. Many mediators have been involved in the cross talk between AC133+/CD34+ cells, endothelial cells, and the tumor cells, but most of these have insufficient clinical benefits as reported by several trials. In this study, we evaluated the secretome of the AC133+/CD34+ stem cells that were isolated by positive selection from human umbilical cord blood and their role in breast cancer progression. Using flow cytometry, we show that the high proliferative AC133+/CD34+ stem cells maintain their capacity to differentiate in to AC133+/CD34+/KDR+ endothelial progenitor cells even after long period of in vitro expansion. In order to evaluate the effect of AC133+/CD34+ stem cells on breast cancer cells, a proliferation (XTT) assay was performed using conditioned medium (CM) from AC133+/CD34+ stem cells and examined on MCF-7 and MDA-MB-231 proliferation. As anticipated, CM significantly induced breast cancer cells proliferation. This effect was in part due to the high expression of a large range of proinflammatory and proangiogenic cytokines in the CM of the AC133+/CD34+ cells. In particular, angiogenin, GRO, IL-8, MCP, and TIMP2. Next, we examined if exosomes, a component of paracrine secretion are involved in the paracrine effect of the AC133+/CD34+ stem cells. Surprisingly, exosomes from AC133+/CD34+ stem cells significantly increased MCF-7 and MDA-MB-231 proliferation at a comparable level as the CM. Further analysis of the exosomes using miRNA array screen reveals that exosomes of AC133+/CD34 cells are highly enriched with oncogenic miRNAs including miR-21-5p, miR-142-3p, and miR-223-3p. These miRNAs are up-regulated in breast cancer. Several studies have confirmed their role in mediating breast cancer cells invasiveness. However, miR-142-3p and miR-223-3p are exclusively expressed in hematopoietic cells. Therefore, we propose that shuttling of the exosomes between AC133+/CD34+cells and breast cancer cells induces breast cancer invasiveness. The analysis of the paracrine interactive mediators between breast cancer cells and AC133+/CD34+ cells is likely to yield viable novel clinically translatable therapeutic targets.

Citation Format: Ghada Ben Rahoma, Rachana Maniyar, Sanjukta Chakraborty, Sarnath Singh, Anitha Srinivasan, Abraham Mittelman, Jan Geliebter, Raj K. Tiwari. Exosomes secreted by AC133+/CD34+cells harbor invasion potentiating miRNAs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3562.

Abstract 1855: Re-purposing traditional Chinese anti-asthma formula ASHMI for triple negative breast cancer

Breast cancer is the most common cancer among women worldwide, contributing to 25.4% of newly diagnosed cancer cases in 2018. Triple negative breast cancer (TNBC) accounts for 10-20% of the breast cancer cases and represents an unmet clinical need because of its higher risk of recurrence and metastasis. Adjuvant therapies have often been employed to prevent secondary recurrence. Traditional Chinese medicine (TCM) formulations have long been used in prevention and cure of many types of diseases because of its anti-inflammatory property. Mainstream treatment modalities for TNBC involve surgery, radiation and chemotherapy (adjuvant or neoadjuvant). Unfortunately, chemotherapy in these patients often lead to resistance, which underscores the importance of alternative therapeutic approaches for this cancer. To this end, we wanted to evaluate anti-carcinogenic property of a TCM formulation ASHMITM developed primarily for asthma treatment. ASHMI™ is an extract of 3 traditional Chinese medicinal herbs-Ganoderma lucidum (Ling-Zhi), Sophora flavescens Ait (Ku-Shen) and Glycyrrhiza uralensis Fischer (Gan-Gao). For this study, triple-negative/basal B mammary carcinoma cell line MDA-MB157 was treated with two different concentrations of ASHMI and cellular proliferation was examined by [3H] thymidine incorporation assay. ASHMITM treated cells showed approximately 74% less [3H] thymidine incorporation indicating dampened proliferation. This observation was validated using western blot analysis with whole cell lysate, showing reduced expression of proliferation markers PCNA and NFκB. Interestingly, an increased expression of tumor suppressor protein cyclin-dependent kinase inhibitor 1 C (p57, Kip2) was observed after ASHMITM treatment. Next, we tested anti-proliferative property of the individual constituents and observed Ganoderma lucidum (GL) extract had a comparable efficacy as the whole formulation at a concentration of 100μg/ml. This observation was further confirmed by western blot and the same expression pattern was observed for PCNA, NFκB and p57. GL was further fractionated into 11 sub-components and each component was tested for the their anti-proliferative activity using similar assays. Fraction 2 with Ganoderenic acid D showed dose-dependent inhibition of cell proliferation and was further tested for its activity at lower concentrations. Ganoderenic acid D had similar efficiency as 100μg/ml of whole GL extract at a concentration as low as 2.5μg/ml suggesting this active compound might be primarily responsible for the anti-proliferative effect of GL. Our studies using an anti-inflammatory formulation of TCM have identified an active anti-carcinogenic compound, Ganoderenic acid D, that could be potentially used as an adjuvant in TNBC therapies.

Citation Format: Sanjukta Chakraborty, Fei Mo, Martin Walsh, Changda Liu, Mingzhuo Cou, Rachana Maniyar, Ghada Ben Rahoma, Sarnath Singh, Tara Jarboe, Michelle Carnazza, Raj Tiwari, Xiu-min Li. Re-purposing traditional Chinese anti-asthma formula ASHMI for triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1855.

Abstract B174: Co-expression of stimulators and inhibitors of T-cell activation in melanoma

Melanoma, one of the most aggressive skin cancers, has steadily been on the rise over the last three decades. With limited treatment options, the recent impetus in immuno-oncology drugs, especially checkpoint inhibitors, has changed the treatment landscape. While anti-CTLA4 and anti-PD1 demonstrated success in clinic, the search for additional targets is needed to enable potent comprehensive curative combination therapies. Our laboratory has characterized and screened five primary patient-derived melanoma cell lines, MEL-2, MEL-V, 3MM, KFM, and GLM-2. While immunomodulatory molecules are canonically present on antigen presenting cells and T-cells, increasing evidence suggests that they are not expressed in isolation. In an effort to identify immunomodulatory molecules expressed on our primary melanoma cells, a comprehensive RT-PCR screen of 29 co-inhibitory and co-stimulatory molecules was carried out. Several molecules including CD160, CD226, TIM1, HVEM, and BTLA were seen to be differentially expressed in melanoma cells compared to normal melanocytes at the mRNA level. Western blots and immunocytochemistry validated the differential expression of these molecules at the protein level. 50-80% of melanoma cases are positive for the BRAFV600E mutation, and are treated with a small molecule inhibitor of the mutated BRAF, vemurafenib (PLX4032). Treatment of these cells with PLX4032 led to an upregulation of transcription factors MITF and AP-1, as well as immunomodulatory molecules, CD160, CD226, TIM1, HVEM, and BTLA, a phenomenon seen only in cells positive for the BRAFV600E lesion. MITF and AP-1, owing to the binding sites present in the promoter regions of these molecules, can drive their expression upon treatment with PLX4032. These additional immune-regulatory molecules of T-cell activation and/or immune tolerance mechanisms are potential targets for a combination therapy with PLX4032 in melanoma patients positive for the BRAFV600E genetic lesion. Our future directions aim to elucidate the role of these molecules on the tumor cells and devise an effective combination with small-molecule inhibitors and immunotherapies.

Citation Format: Rachana Maniyar, Robert Freund, Aryan Malhotra, Sanjukta Chakraborty, Jan Geliebter, Marc Wallack, Raj K. Tiwari. Co-expression of stimulators and inhibitors of T-cell activation in melanoma [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B174.

Ethanol Enhances Estrogen Mediated Angiogenesis in Breast Cancer

Angiogenesis, a highly regulated process, is exploited by tumors like breast cancer to ensure a constant supply of oxygen and nutrients and is key for tumor survival and progression. Estrogen and alcohol independently have been observed to contribute to angiogenesis in breast cancer but their combinatorial effects have never been evaluated. The exact mechanism by which estrogen and alcohol contribute to breast cancer angiogenesis remains to be elucidated. In this study, we defined the in vitro effects of the combination of estrogen and alcohol in breast cancer angiogenesis using the tubulogenesis and scratch wound assays. Conditioned media, generated by culturing the murine mammary cancer cell line, TG1-1, in estrogen and ethanol, enhanced tubule formation and migration as well as modulated the MAP Kinase pathway in the murine endothelial cell line, SVEC4-10. Additionally, estrogen and ethanol in combination enhanced the expression of the pro-angiogenic factors VEGF, MMP-9, and eNOS, and modulated Akt activation. These observations suggest that TG1-1 cells secrete pro-angiogenic molecules in response to the combination of estrogen and ethanol that modulate the morphological and migratory properties of endothelial cells. The data presented in this study, is the first in attempting to link the cooperative activity between estrogen and ethanol in breast cancer progression, underscoring correlations first made by epidemiological observations linking the two.

Abstract 2059: Alcohol enhances estrogen-responsive breast cancer neovascularization

The pleiotropic effects of estrogen in breast cancer development have been observed at both the initiation and progression phases. Interestingly, alcohol, as a dietary component, has been observed to possess estrogenic activity, but the synergistic interaction between alcohol and estrogen and its cellular targets remains undefined. Our previous study identified neovascularization as a cellular target of estrogen that was mediated by the mobilization of bone marrow-derived endothelial progenitor cells (BM-EPCs) and their subsequent incorporation within the tumor mass. The present study was undertaken to define the synergistic interaction between estrogen and alcohol using a cell culture model. To examine the effects of both estrogen and alcohol on breast cancer progression, we developed an in vitro model using the murine mammary tumor cell line, TG1-1, and the murine endothelial cell line, SVEC4-10. Neovascularization was assayed by the tubulogenesis and scratch wound assays as well as quantitating the expression of various provasculogenic markers. Conditioned media, generated by culturing the murine mammary cancer cell line, TG1-1, in estrogen and ethanol, was observed to enhance tubule formation and migration of the murine endothelial cell line, SVEC4-10. In addition, the TG1-1 conditioned media enhanced the prosurvival MAP kinase-signaling pathway in SVEC4-10 cells. Presumably, the observed enhancement of both endothelial cell tubulogenesis and migration is in part attributed to provasculogenic proteins secreted by TG1-1 cells. In order to address this, Western blot analysis using TG1-1 cell lysates indicated an increase in VEGF, MMP-9, and eNOS expression in presence of alcohol and estrogen. As a whole, our data suggest that both estrogen and alcohol function to enhance expression of key provasculogenic molecules in breast cancer cells, which in turn modulates the morphologic, migratory, and survival properties of endothelial cells.

Citation Format: Natalie C. Cruz, Rachana Maniyar, Robert Suriano. Alcohol enhances estrogen-responsive breast cancer neovascularization [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2059.

Abstract 2053: Exosomes from AC133+/CD34+ stem cells mediate a paracrine effect in breast cancer cells

Exciting advances in the treatment of breast cancer have occurred over the past decade. However, the efficacy of the current therapeutic modalities is still limited by drug toxicity, resistance, and lack of predictive and prognostic biomarkers. Breast cancer remains the second leading cause of cancer death among women in the U.S. Thus, the development of new therapeutic targets and further understanding of the tumor microenvironment is extremely crucial for accelerating the progress against breast cancer. Human AC133+/CD34+ stem cells serve as a highly promising and novel therapeutic option for targeting tumor angiogenesis. We and others have demonstrated the incorporation of bone marrow-derived AC133+/CD34+/KDR+ endothelial progenitor cells in the neovasculature around implanted tumors supporting their growth and spread. Many mediators have been implicated in the crosstalk between AC133+/CD34+/KDR+ endothelial progenitor cells, endothelial cells, and the tumor cells, but most of these have limited clinical benefits as reported by several trials. In this study, we analyzed the secretome of the AC133+/CD34+ stem cells that were isolated by positive selection from human umbilical cord blood and evaluated their role in breast cancer progression. Our results show that AC133+/CD34+ stem cells exhibited significant growth potential that was manifested as seventy-five fold increase in cell number after 10 days in culture. Flow cytometry demonstrated that AC133+/CD34+ stem cells preserve their capacity to differentiate into AC133+/CD34+/KDR+ endothelial progenitor cells even after long term in vitro expansion. In order to evaluate the effect of AC133+/CD34+ stem cells on breast cancer cells, we performed a simple proliferation (XTT) assay using conditioned medium (CM) from AC133+/CD34+ stem cells and tested on MCF-7 and MDA-MB-231 proliferation. As expected, CM significantly induced proliferation of breast cancer cells. This effect was in part due to the high expression of a repertoire of proinflammatory and proangiogenic cytokines in the CM of the AC133+/CD34+ stem cells. In particular, angiogenin, GRO, IL-8, MCP, PDGF.BB, TIMP2. Further, we examined if exosomes, a component of paracrine secretion are involved in the paracrine effect of the AC133+/CD34+ stem cells. Interestingly, exosomes from AC133+/CD34+ stem cells significantly enhanced MCF-7 and MDA-MB-231 proliferation at a comparable level as the CM. Further analysis of the exosomes reveals that the pro-proliferative miR-141-3p, miR-182-5p, miR-200b-3p, and miR-203a are highly expressed in AC133+/CD34+ exosomes. The analysis of the paracrine interactive mediators between breast cancer cells, AC133+/CD34+ stem cells, and AC133+/CD34+/KDR+ endothelial progenitor cells is likely to yield viable novel clinically translatable therapeutic targets.

Citation Format: Ghada Ben Rahoma, Neha Tuli, Rachana Maniyar, Sanjukta Chakraborty, Sarnath Singh, Abraham Mittelman, Jan Gelibter, Raj K. Tiwari. Exosomes from AC133+/CD34+ stem cells mediate a paracrine effect in breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2053.

Macrophage inflammatory factors promote epithelial-mesenchymal transition in breast cancer

The majority of breast cancers (90-95%) arise due to mediators distinct from inherited genetic mutations. One major mediator of breast cancer involves chronic inflammation. M1 macrophages are an integral component of chronic inflammation and the breast cancer tumor microenvironment (TME). Previous studies have demonstrated that up to 50% of the breast tumor comprise of tumor-associated macrophages (TAMs) and increased TAM infiltration has been associated with poor patient prognosis. Furthermore, breast cancer associated deaths are predominantly attributed to invasive cancers and metastasis with epithelial-mesenchymal transition (EMT) being implicated. In this study, we investigated the effects of cellular crosstalk between TAMs and breast cancer using an in vitro model system. M1 polarized THP-1 macrophage conditioned media (CM) was generated and used to evaluate cellular and functional changes of breast cancer lines T47D and MCF-7. We observed that T47D and MCF-7 exhibited a partial EMT phenotype in the presence of activated THP-1 CM. Additionally, MCF-7 displayed a significant increase in migratory and invasive properties. We conclude that M1 secretory factors can promote a partial EMT of epithelial-like breast cancer cells. The targeting of M1 macrophages or their secretory components may inhibit EMT and limit the invasive potential of breast cancer.

Elevated 20-HETE in metabolic syndrome regulates arterial stiffness and systolic hypertension via MMP12 activation

Arterial stiffness plays a causal role in development of systolic hypertension. 20-hydroxyeicosatetraeonic acid (20-HETE), a cytochrome P450 (CYP450)-derived arachidonic acid metabolite, is known to be elevated in resistance arteries in hypertensive animal models and loosely associated with obesity in humans. However, the role of 20-HETE in the regulation of large artery remodeling in metabolic syndrome has not been investigated. We hypothesized that elevated 20-HETE in metabolic syndrome increases matrix metalloproteinase 12 (MMP12) activation leading to increased degradation of elastin, increased large artery stiffness and increased systolic blood pressure. 20-HETE production was increased ~7 fold in large, conduit arteries of metabolic syndrome (JCR:LA-cp, JCR) vs. normal Sprague-Dawley (SD) rats. This correlated with increased elastin degradation (~7 fold) and decreased arterial compliance (~75% JCR vs. SD). 20-HETE antagonists blocked elastin degradation in JCR rats concomitant with blocking MMP12 activation. 20-HETE antagonists normalized, and MMP12 inhibition (pharmacological and MMP12-shRNA-Lnv) significantly improved (~50% vs. untreated JCR) large artery compliance in JCR rats. 20-HETE antagonists also decreased systolic (182 ± 3 mmHg JCR, 145 ± 3 mmHg JCR + 20-HETE antagonists) but not diastolic blood pressure in JCR rats. Whereas diastolic pressure was fully angiotensin II (Ang II)-dependent, systolic pressure was only partially Ang II-dependent, and large artery stiffness was Ang II-independent. Thus, 20-HETE-dependent regulation of systolic blood pressure may be a unique feature of metabolic syndrome related to high 20-HETE production in large, conduit arteries, which results in increased large artery stiffness and systolic blood pressure. These findings may have implications for management of systolic hypertension in patients with metabolic syndrome.

Abstract 122: 20-HETE Antagonists Normalize Large Artery Stiffness and Systolic Blood Pressure in Metabolic Syndrome

Large artery stiffness is a causal factor in development of systolic hypertension. 20-hydroxyeicosatetraeonic acid (20-HETE), a cytochrome CYP450-derived arachidonic acid metabolite, is known to be elevated in resistance arteries in hypertensive animal models and in obesity in humans, but the role of 20-HETE in regulation of large artery remodeling in metabolic syndrome has not been investigated. Unlike normal (Sprague-Dawley (SD)) rats, large arteries (aorta, carotid and >100μM mesenteric arteries) of metabolic syndrome rats (JCR:LA-cp, JCR) express CYP4A and 4F, CYP450s which make 20-HETE in rats (2-fold increase vs. SD). Consequently, 20-HETE production is elevated in large arteries of JCR rats. We hypothesized that this elevated 20-HETE increases matrix metalloproteinase 12 (MMP12, an elastase) activation leading to increased degradation of elastin, increased large artery stiffness and increased systolic blood pressure. A 3-4 fold increase in 20-HETE production in large arteries of JCR vs. SD rats correlated with increased elastin degradation (3-6 fold) and increased arterial stiffness (~75%). 20-HETE antagonists blocked elastin degradation in JCR rats concomitant with blocking MMP12 activation. Importantly, 20-HETE antagonists and MMP12 inhibition (pharmacological and MMP12-shRNA-Lnv) significantly decreased (~60% vs. untreated JCR) large artery stiffness in JCR rats. 20-HETE antagonists also decreased systolic (182±3 mmHg JCR, 145±3 mmHg JCR+20-HETE antagonists) but not diastolic (125±4 mmHg JCR, 124±4 mmHg JCR+20-HETE antagonists) blood pressure in JCR rats. Whereas diastolic pressure was fully angiotensin II (Ang II)-dependent, systolic pressure was only partially Ang II-dependent, and large artery stiffness in JCR rats was Ang II-independent. These results suggest that 20-HETE-dependent regulation of systolic blood pressure may be a unique feature of metabolic syndrome related to high CYP4A/4F expression and resultant high 20-HETE production in large conduit arterial stiffness, which is a primary determinant of systolic blood pressure. These findings may have implications for management of systolic hypertension in patients with metabolic syndrome.

Abstract 3973: Role of thyroid tumor microenvironment secretome in cancer initiation and progression

The incidence of thyroid cancer in the United States is on a rise with an appreciably high disease recurrence rate of 20-30%. Tumor associated macrophages (TAMs) release cytokines, chemokines and other secretory components like exosomes which aid in thyroid tumor progression and metastasis. In our previous study on thyroid tumor microenvironment, we established that M1 polarized pro-inflammatory macrophages modulate thyroid cancer phenotype. TAMs secretome, consisting of pro-inflammatory cytokines such as TGF-β, IL6, TNF-α, IL-1β, amongst others, induce epithelial to mesechymal transition (EMT) in thyroid cancer cells promoting tumor metastasis and propagation. In our present study, we used an in vitro model system to assess the effects of secretory molecules called exosomes, in the thyroid tumor microenvironment. We used thyroid cancer cell lines: BCPAP (papillary), 8505C (anaplastic) and CGTHW-1 (follicular) to represent the spectrum of clinically observed thyroid cancers. THP-1 monocyte/macrophage cell line was used to denote the inflammatory component. Thyroid cancer cells treated with activated M1 polarized THP-1 macrophage exosomes showed halt in proliferation, transformation to mesenchymal phenotype as well as modulation in expression of EMT markers, such as vimentin and NFk-B, indicative of induction of EMT in thyroid cancer cells. Interestingly, secretory exosomes from anaplastic thyroid cancer cells led to activation of THP-1 monocytes. Since the exosomal cargo is the reflection and fingerprint of its originating parental cells, we profiled exosomal miRNA derived from thyroid cancer cells and THP1 cells. Modulation of various miRNA in follicular and anaplastic thyroid cancer exosomes was observed, when compared to papillary thyroid cancer exosomes. We detected a down regulation of miR-138-5p, miR-146a-5p, miR-26a-5p, miR-26b-5p, miR-34a-5p and miR-31-5p in anaplastic and follicular cancer exosomes, which may play a role in promoting cancer invasion and metastasis. In comparison to papillary thyroid cancer exosomes, an upregulation of miR-214-3p, miR-200a-3p, miR-298, miR-299-3p, and miR-302a-3p was ascertained in follicular thyroid cancer exosomes. Conversely, we noted a down regulation of these miRNAs in anaplastic thyroid cancer exosomes. These distinct miRNA expressions in cancer secretome will provide new insights into the tumor development and dissemination. Our findings suggest an important crosstalk between the secretome of thyroid cancer cells and inflammatory cells in tumor microenvironment, defining thyroid cancer phenotype. These exosomal miRNA serve as early diagnostic markers of thyroid cancer differentiation as well as targets for novel therapies specifically for anaplastic thyroid cancer.

Citation Format: Neha Yashpal Tuli, Ameet Kamat, Rachana Maniyar, Ghada Ben Rahoma, Sanjukta Chakraborty, Sarnath Singh, Augustine Moscatello, Jan Geliebter, Raj K. Tiwari. Role of thyroid tumor microenvironment secretome in cancer initiation and progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3973. doi:10.1158/1538-7445.AM2017-3973

Abstract 793: Human endothelial progenitor cells: A new target for anti-vascular therapy

Breast cancer affects one in eight women in the USA. Early diagnosis and newer treatment modalities have rendered breast cancer manageable. However, triple negative breast cancer is still difficult to treat and warrantes a search for newer targets. One strategy that has emerged in cancer research involves targeting of tumor associated blood vessels which provide growing tumors with oxygenated blood and growth factors necessary for maintenance and metastasis. Antiangiogenic drug therapy is transient and has not been able to gain mainstream therapeutic modality. We discovered that endothelial progenitor cells (EPCs) are mobilized from the bone marrow to the tumor site and contribute to the development of breast tumor vessel formation in an estrogen dependent manner. Therefore, characterization of tumor associated endothelial progenitor cells in breast cancer may provide a more specific antivascular therapy. Using the highly proliferative human umbilical cord blood derived EPCs, having the phenotype (CD133+, CD34+, VEGFR-2+), the effect of growth factor and chemokine rich EPCs conditioned medium (CM) was assessed in luminal (MCF-7), and post-EMT (MDA-MB-231) breast carcinoma cell lines. We observed an initial halt in cellular proliferation in MCF-7 followed by a significant increase in proliferation after forty eight hours of treatment. On the other hand, MDA-MB-231 showed decreased proliferation even after forty eight hours of treatment. Treating the EPCs with breast cancer conditioned medium resulted in morphological and cellular growth changes in the EPCs. MDA-MB-231 CM resulted in an increase of the EPCs proliferation and differentiation by increasing the number of spindle shaped attaching cells, and MCF-7 CM resulted only in an increase in the differentiation rate by increasing the number of cell clusters. This increase in EPCs proliferation and differentiation associated with MDA-MB-231 CM treatment might explain the invasiveness of this breast cancer cells through the increase in the tumor associated neovascularization. The analysis of the paracrine interaction between breast cancer cells and EPCs along with the associated cellular changes will facilitate identification of the interactive mediators and subsequent development of effective antivascular therapy.

Citation Format: Ghada Ben Rahoma, Neha Tuli, Rachana Maniyar, Sanjukta Chakraborty, Sarnath Singh, Abraham Mittelman, Raj K. Tiwari. Human endothelial progenitor cells: A new target for anti-vascular therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 793. doi:10.1158/1538-7445.AM2017-793

Abstract 3134: Hierarchical gene master regulators of papillary and anaplastic thyroid cancer phenotype

The incidence of thyroid cancer (TCa) has doubled in the last decade. Papillary thyroid cancer (PTC), that comprises of 80% of all TCas, is treatable with great outcomes. However, undifferentiated anaplastic thyroid cancer (ATC), with very poor prognosis, is considered a clinical challenge and currently a losing battle. Moreover, the molecular mechanisms responsible for various forms of TCa are largely unknown. We believe that the cells of histopathologically distinct regions of a heterogeneous thyroid tumor are governed by different sets of master gene regulators. The smart manipulation of such master genes will be able to selectively destroy cancer cells but not normal tissue, opening a novel and much more effective avenue in the thyroid cancer targeted gene therapy. Our analysis established the gene hierarchical governance in each region based on their Gene Commanding Height (GCH). GCH is a measure that combines the gene expression coordination with other genes and the expression stability among biological replicas provided by the internal homeostatic mechanisms. Here, we provide experimental evidence that standard papillary (BCPAP) and anaplastic (8505C) human thyroid cancer cell lines have different master regulators. We identified the master regulators of BCPAP and 8505C, and determined their GCH. Transfection of master gene regulators of a particular cell line has significantly larger effects on the cell line they command than on other cells. We found that the stable transfection with TMEM194A, a nuclear envelope protein, regulated twice more genes in BCPAP than in 8505C cells. The analysis using human thyroid cancer cells reaffirmed our hypothesis of the existence of hierarchical master gene regulators and that the phenotypic changes can be manipulated with the introduction of these genes. We further validate these concepts using human thyroid biopsy samples. We found substantial differences in the GCH scores of cancer versus normal tissue of a surgically removed 32.0mm papillary carcinoma from the left lobe of a 33y old male. Because of such differences between the cancer region and the normal tissue, manipulation of cancer regulators is expected to affect the cancer cells in a greater degree than the normal cells. These results suggest that we have defined a master gene regulator hierarchy in thyroid cancer and extrapolation of this analysis to compare anaplastic and papillary thyroid cancer will lead to novel gene therapeutic modalities. Our long-term goal is to identify master regulators of cancer nodules for each patient and develop personalized cancer therapy targeting these master regulators.

Citation Format: Neha Yashpal Tuli, Craig Berzofsky, Rachana Maniyar, Sanjukta Chakraborty, Ghada Ben Rahoma, Sarnath Singh, Jan Geliebter, Raj K. Tiwari, Sanda Iacobas, Dumitru A. Iacobas. Hierarchical gene master regulators of papillary and anaplastic thyroid cancer phenotype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3134. doi:10.1158/1538-7445.AM2017-3134

Abstract 5105: Exosomes secreted by proinflammatory macrophages modulate breast cancer

Multiple cell types reside within the tumor microenvironment (TME) including cancer stem cells, stromal cells, and inflammatory cells. Cellular crosstalk is initiated between these cells through a variety of secreted biomolecules such as cytokines, growth factors, and exosomes. The role of inflammation and numerous secretory factors within the TME have been implicated in the development and progression of various cancers including breast. In this study, we wanted to evaluate the effect of macrophages (a major constituent of inflammation) on breast cancer development. Our study focused on macrophage secreted exosomes which are membraneous nanovesicles that contain various miRNA, mRNA, and proteins. We hypothesized that macrophage secreted exosomes will modulate breast cancer phenotype. An in vitro cell culture system was used in this study to examine macrophage exosome treatments on breast cancer cell lines MCF-7 (ER+) and MDA-MB 231 (ER-, PR-, HER2/neu-). Human monocytic THP-1 monocytes were activated with a common phorbol ester TPA (12-O-tetradecanoylphorbol-13-acetate) and conditioned media (CM) was collected following 48 h. Exosomes were isolated from THP-1 CM via the use of an exosome isolation reagent and standard centrifugation. Breast cancer cells were then treated with THP-1 exosomes and cell morphology, proliferation, MEK/ERK and PI3K/AKT signaling pathways, and cell cycle were evaluated. MCF-7 and MDA-MB 231 exhibited round and spindle-like morphologies as well as a significant decrease in proliferation at 24 h treatments. Furthermore, MDA-MB 231 displayed increased p-ERK, while MCF-7 showed increased p-MEK following Western blot analysis. Both cell lines exhibited decreased p-AKT and p-S6 kinase expression. Cell cycle analysis showed that MCF-7 and MDA-MB 231 arrested at G2/M at 24 h exosome treatments. THP-1 exosome treatments led to a significant increase in MDA-MB 231 senescence as determined by a senescence assay looking at senescence-associated beta-galactosidase. Increased p21 and decreased Cdc2/Cyclin B1 was also observed which indicates a G2/M arrest. We conclude that specific macrophage secreted exosomes may induce breast cancer cell senescence and affect breast cancer progression.

Citation Format: Robert Bronislaw Bednarczyk, Neha Y. Tuli, Ghada Ben Rahoma, Rachana Maniyar, Abraham Mittelman, Raj K. Tiwari. Exosomes secreted by proinflammatory macrophages modulate breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5105.