Targeting Tumor Stroma Research Articles

Phytochemicals and Their Nanoformulations for Targeting Hepatocellular Carcinoma: Exploring Potential and Targeting Strategies.

Hepatocellular carcinoma (HCC) continues to pose a global health concern, necessitating the exploration of innovative therapeutic approaches. In the recent decade, targeting tumor stroma consisting of extracellular matrix (ECM), immune cells, vascular system, hypoxia, and also suppressive mechanisms in HCC has attracted interest in repressing tumor growth and metastasis. Phytochemicals have attained considerable attention because of their manifold biological effects and high capacity for anticancer activities. These chemical agents have shown the capability to modulate different cells and secretions within the stroma of malignancies. In recent years, the development of nanoformulations has further enhanced the therapeutic potential of phytochemicals by improving their solubility, bioavailability, and targeted delivery to tumor tissues. This review aims to provide an encyclopedic overview of the potential of phytochemicals and their nanoformulations as promising therapeutic strategies for targeting HCC. The review initially highlights the broad array of phytochemicals exhibiting potent anticancer properties, including flavonoids, alkaloids, terpenoids, and phenolic compounds, among others. Then, the nanoformulations and modification of these agents will be reviewed. Finally, we will review the latest experiments that have examined the modulation of HCC using adjuvant phytochemicals and their nanoformulations.

Targeting the pancreatic tumor microenvironment by plant-derived products and their nanoformulations.

Pancreatic cancer remains a significant health issue with limited treatment options. The tumor stroma, a complex environment made up of different cells and proteins, plays a crucial role in tumor growth and chemoresistance. Targeting tumor stroma, consisting of diverse non-tumor cells such as fibroblasts, extracellular matrix (ECM), immune cells, and also pre-vascular cells is encouraging for remodeling solid cancers, such as pancreatic cancer. Remodeling the stroma of pancreas tumors can be suggested as a strategy for reducing resistance to chemo/immunotherapy. Several studies have shown that phytochemicals from plants can affect the tumor environment and have anti-cancer properties. By targeting key pathways involved in stromal activation, phytochemicals may disrupt communication between the tumor and stroma and make tumor cells more sensitive to different treatments. Additionally, phytochemicals have immunomodulatory and anti-angiogenic properties, all of which contribute to their potential in treating pancreatic cancer. This review will provide a detailed look at how phytochemicals impact the tumor stroma and their effects on pancreatic tumor growth, spread, and response to treatment. It will also explore the potential of combining phytochemicals with other treatment options like chemotherapy, immunotherapy, and radiation.

Role of autophagy in cancer-associated fibroblast activation, signaling and metabolic reprograming.

Tumors not only consist of cancerous cells, but they also harbor several normal-like cell types and non-cellular components. cancer-associated fibroblasts (CAFs) are one of these cellular components that are found predominantly in the tumor stroma. Autophagy is an intracellular degradation and quality control mechanism, and recent studies provided evidence that autophagy played a critical role in CAF formation, metabolic reprograming and tumor-stroma crosstalk. Therefore, shedding light on the autophagy and its role in CAF biology might help us better understand the roles of CAFs and the TME in cancer progression and may facilitate the exploitation of more efficient cancer diagnosis and treatment. Here, we provide an overview about the involvement of autophagy in CAF-related pathways, including transdifferentiation and activation of CAFs, and further discuss the implications of targeting tumor stroma as a treatment option.

Comparison of Clinico-Demographic and Histological Parameters Between Young and Old Patients With Oral Squamous Cell Carcinoma.

Among the epithelial malignancies of the head and neck region, oral squamous cell carcinoma (OSCC) arising from the oral mucosa is the commonest type. OSCC is common in the older population; however, recent epidemiological data indicate an increase in the incidence in the younger age group. The present study was designed to compare the clinicopathological characteristics of OSCC between young and old South Indian patients. All the histopathologically confirmed cases of OSCC were retrieved from the department archives. Patients aged more than 40 years were considered Group I, and patients aged less than or equal to 40 were considered Group II. Age, gender, laterality, site, degree of keratinization, nuclear pleomorphism, pattern of invasion, lymphoplasmacytic infiltration, grade, tumor budding (TB), and tumor stroma ratio (TSR) were assessed. Among 510 patients reported with OSCC, 442 were aged above 40 years, and 68 were aged 40 years or younger. Nuclear pleomorphism, TB, and stroma-rich ratio were statistically higher in younger OSCC patients (p=0.00). The results of our study support the fact that OSCC in younger individuals is more aggressive. Targeting TB and tumor stroma could provide new strategies for the management of OSCC.

Dysregulated miRNAs modulate tumor microenvironment associated signaling networks in pancreatic ductal adenocarcinoma.

The desmoplastic and complex tumor microenvironment of pancreatic ductal adenocarcinoma (PDAC) has presented tremendous challenges for developing effective therapeutic strategies. Strategies targeting tumor stroma, albeit with great potential, have met with limited success due to the lack of knowledge on the molecular dynamics within the tumor microenvironment (TME). In pursuit of a better understanding of the influence of miRNAs on TME reprogramming and to explore circulating miRNAs as diagnostic and prognostic biomarkers for PDAC, using RNA-seq, miRNA-seq, and single-cell RNA-seq (scRNA-seq), we investigated the dysregulated signaling pathways in PDAC TME modulated by miRNAs from plasma and tumor tissue. Our bulk RNA-seq in PDAC tumor tissue identified 1445 significantly differentially expressed genes with extracellular matrix and structure organization as the top enriched pathways. Our miRNA-seq identified 322 and 49 abnormally expressed miRNAs in PDAC patient plasma and tumor tissue, respectively. We found many of the TME signaling pathways were targeted by those dysregulated miRNAs in PDAC plasma. Combined with scRNA-seq from patient PDAC tumor, our results revealed that these dysregulated miRNAs were closely associated with extracellular matrix (ECM) remodeling, cell-ECM communication, epithelial-mesenchymal transition, as well as immunosuppression orchestrated by different cellular components of TME. The findings of this study could assist the development of miRNA-based stromal targeting biomarkers or therapy for PDAC patients.

Near-infrared-induced drug release from antibody-drug double conjugates exerts a cytotoxic photo-bystander effect.

Ideal cancer treatments specifically target and eradicate tumor cells without affecting healthy cells. Therefore, antibody‐based therapies that specifically target cancer antigens can be considered ideal cancer therapies. Antibodies linked with small‐molecule drugs (i.e., antibody–drug conjugates [ADCs]) are widely used in clinics as antibody‐based therapeutics. However, because tumors express antigens heterogeneously, greater target specificity and stable binding of noncleavable linkers in ADCs limit their antitumor effects. To overcome this problem, strategies, including decreasing the binding strength, conjugating more drugs, and targeting tumor stroma, have been applied, albeit with limited success. Thus, further technological advancements are required to remotely control the ADCs. Here, we described a drug that is photo‐releasable from an ADC created via simple double conjugation and its antitumor effects both on target and nontarget tumor cells. Specifically, noncleavable T‐DM1 was conjugated with IR700DX to produce T‐DM1‐IR700. Although T‐DM1‐IR700 itself is noncleavable, with NIR‐light irradiation, it can release DM1‐derivatives which elicited antitumor effect in vitro mixed culture and in vivo mixed tumor model which are mimicking heterogeneous tumor‐antigen expression same as real clinical tumors. This cytotoxic photo‐bystander effect occurred in various types mixed cultures in vitro, and changing antibodies also exerted photo‐bystander effects, suggesting that this technology can be used for targeting various specific cancer antigens. These findings can potentially aid the development of strategies to address challenges associated with tumor expression of heterogeneous antigen.

Abstract 3983: Direct contact of heterogeneous fibroblasts with cancer cells regulates the invasive phenotype of prostate cancer cells

Abstract In the tumor microenvironment of prostate cancer (PCa), cancer cells frequently invade the surrounding stroma in the way of single cell migration (SCM) or collective cell migration (CCM). This phenomenon can be responsible for the heterogeneous formation of structural atypia such as Gleason pattern. Generally, PCa cells undergo a phenotypic change which is called the epithelial-to-mesenchymal transition (EMT), e.g., downregulation of epithelial cell-cell adhesion molecules such as E-cadherin and gain of mesenchymal morphology and motility. The surrounding stroma is mainly composed of fibroblasts and extracellular matrix (ECM). We hypothesize that direct contact-mediated interactions at the interface between PCa cells and fibroblasts/ECM can trigger numerous changes in PCa cells including morphology and motility. In this study, we investigated the roles of fibroblasts in the three-dimensional (3D) morphogenesis of PCa cells on a viscous substrate. To examine the effects of fibroblasts on the 3D morphogenesis of PCa cells on Matrigel, we mixed human PCa cell line LNCaP cells with commercially available normal human prostate stromal cells (PrSC) or nine primary cultures of prostate fibroblasts (pcPrFs and NPFs) isolated from patients with PCa and bladder cancer. The 3D morphogenesis of LNCaP cells mixed with fibroblasts on Matrigel was confirmed by E-cadherin immunohistochemical staining. All ten fibroblasts alone were aggregated on Matrigel, whereas LNCaP cells alone were not. LNCaP cells mixed with six fibroblasts (PrSC, pcPrF-M5, pcPrF-M23, pcPrF-M24, pcPrF-M28, and pcPrF-M31) formed a deep crater-like hole on Matrigel. In the 3D structure, the upper and lower tiers were composed of LNCaP cells and fibroblasts, respectively. Of note, direct contact of four fibroblasts (NPF-M13, pcPrF-M7, pcPrF-M10, and pcPrF-M26) with LNCaP cells decreased the aggregation of fibroblasts on Matrigel. Five of six fibroblasts (PrSC, pcPrF-M5, pcPrF-M23, pcPrF-M28, and pcPrF-M31) induced SCM of LNCaP cells, while only one fibroblasts (pcPrF-M24) induced CCM. In the scratch assay, the cell motility of CCM-inducing fibroblasts was slower than that of SCM-inducing fibroblasts. Expression pattern of primary cilia in SCM-inducing fibroblasts was changed by mixing with LNCaP cells, whereas that in CCM-inducing fibroblasts was not. PCa is quite interesting because of the multi-focal and heterologous progression of primary tumors. The heterogeneous stromal compartment in PCa tissues contains multiple populations of fibroblasts that are associated with morphology and motility of PCa cells. Here our results showed that direct contact of heterogeneous fibroblasts with PCa cells on Matrigel regulated the invasive phenotype of PCa cells such as SCM and CCM. Impairing the malignant phenotype of fibroblasts in PCa tissues, e.g., differentiation therapy targeting tumor stroma, may abrogate PCa cell invasion. Citation Format: Kenichiro Ishii, Yasuhisa Nakagawa, Taku Shirai, Masako Ichishi, Masaya Fujiwara, Daisuke Kato, Chise Matsuda, Yoshifumi Hirokawa, Yoshiki Sugimura, Masaki Inagaki, Masatoshi Watanabe. Direct contact of heterogeneous fibroblasts with cancer cells regulates the invasive phenotype of prostate cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3983.

Three-dimensional models of breast cancer-fibroblasts interactions.

Tumor stroma plays an important role in progression of cancers to a fatal metastatic disease. Modern treatment strategies are considering targeting tumor stroma to improve outcomes for cancer patients. A current challenge to develop stroma-targeting therapeutics is the lack of preclinical physiologic tumor models. Animal models widely used in cancer research lack human stroma and are not amenable to screening of chemical compounds for cancer drug discovery. In this review, we outline in vitro three-dimensional tumor models that we have developed to study the interactions among cancer cells and stromal cells. We describe development of the tumor models in a modular fashion, from a spheroid model to a sophisticated organotypic model, and discuss the importance of using correct physiologic models to recapitulate tumor-stromal signaling. These biomimetic tumor models will facilitate understanding of tumor-stromal signaling biology and provide a scalable approach for testing and discovery of cancer drugs.

Core\u2013shell nanoparticles suppress metastasis and modify the tumour-supportive activity of cancer-associated fibroblasts

BackgroundAlthough accumulating evidence suggests that the crosstalk between malignant cells and cancer-associated fibroblasts (CAFs) actively contributes to tumour growth and metastatic dissemination, therapeutic strategies targeting tumour stroma are still not common in the clinical practice. Metal-based nanomaterials have been shown to exert excellent cytotoxic and anti-cancerous activities, however, their effects on the reactive stroma have never been investigated in details. Thus, using feasible in vitro and in vivo systems to model tumour microenvironment, we tested whether the presence of gold, silver or gold-core silver-shell nanoparticles exerts anti-tumour and metastasis suppressing activities by influencing the tumour-supporting activity of stromal fibroblasts.ResultsWe found that the presence of gold-core silver-shell hybrid nanomaterials in the tumour microenvironment attenuated the tumour cell-promoting behaviour of CAFs, and this phenomenon led to a prominent attenuation of metastatic dissemination in vivo as well. Mechanistically, transcriptome analysis on tumour-promoting CAFs revealed that silver-based nanomaterials trigger expressional changes in genes related to cancer invasion and tumour metastasis.ConclusionsHere we report that metal nanoparticles can influence the cancer-promoting activity of tumour stroma by affecting the gene expressional and secretory profiles of stromal fibroblasts and thereby altering their intrinsic crosstalk with malignant cells. This potential of metal nanomaterials should be exploited in multimodal treatment approaches and translated into improved therapeutic outcomes.

Mesenchymal stromal cell activation by breast cancer secretomes in bioengineered 3D microenvironments

Mesenchymal stromal cells (MSCs) are key contributors of the tumour microenvironment and are known to promote cancer progression through reciprocal communication with cancer cells, but how they become activated is not fully understood. Here, we investigate how breast cancer cells from different stages of the metastatic cascade convert MSCs into tumour-associated MSCs (TA-MSCs) using unbiased, global approaches. Using mass spectrometry, we compared the secretomes of MCF-7 cells, invasive MDA-MB-231 cells, and sublines isolated from bone, lung, and brain metastases and identified ECM and exosome components associated with invasion and organ-specific metastasis. Next, we used synthetic hydrogels to investigate how these different secretomes activate MSCs in bioengineered 3D microenvironments. Using kinase activity profiling and RNA sequencing, we found that only MDA-MB-231 breast cancer secretomes convert MSCs into TA-MSCs, resulting in an immunomodulatory phenotype that was particularly prominent in response to bone-tropic cancer cells. We have investigated paracrine signalling from breast cancer cells to TA-MSCs in 3D, which may highlight new potential targets for anticancer therapy approaches aimed at targeting tumour stroma.

P3.03-19 The Lysyl Oxidase like-1 Promotes NSCLC Tumorigenecity Through Increased Matrix Reorganization and Stiffness

The importance of the stroma in tumorigenicity has been increasingly recognized in the past few years and targeting tumor stroma has become a new strategy for the development of new therapies. The lysyl oxidase like-1 (LOXL1) is a matrix cross-linking enzyme, essentially secreted by cancer-associated fibroblasts (CAFs) in the stroma. We previously showed that LOXL1 expression strongly correlated with integrin α11 expression, a collagen receptor that promotes NSCLC tumorigenecity, suggesting that LOXL1 may also contribute to lung tumor growth and metastasis by modifying the stromal collagen matrix. Primary CAFs (CAF094) isolated from a NSCLC resection specimen and immortalized with hTERT were infected with full length LOXL1 (LOXL1 overexpression), LOXL1 shRNA (LOXL1 knockdown) or with their respective controls, using a lentiviral system. To investigate the impact of LOXL1 on collagen matrix reorganization, we allowed CAFs expressing different levels of LOXL1 to contract collagen matrices. Contracted collagen matrices have then been submitted to second harmonic generation to analyze collagen fibers. We established the role of LOXL1 in lung carcinoma invasion and growth using an in vitro organotypic model and an in vivo xenograft model, respectively. LOXL1-overexpressing CAFs embedded in collagen lattices displayed greater ability to reorganize the collagen matrix than those with lower LOXL1 expression. Furthermore, analysis of the collagen matrix demonstrated that LOXL1 contributed to more linear and dense collagen fibers organization. As a consequence of collagen matrix reorganization, invasion of the lung carcinoma H661 cell line significantly increased in an organotypic model in presence of LOXL1-overexpressing CAFs. Moreover, we showed that loss of Loxl1 in mice inhibited subcutaneous growth of the lung adenocarcinoma H4006 cell line compared to the mouse wild-type counterparts. We demonstrated that overexpression of LOXL1 in NSCLC tumor stroma results in an increased of tumor growth and invasion, due to a change in the matrix reorganization. Thus, LOXL1 appears as an interesting target to improve the outcome of lung cancer.

BFGF Promotes Migration and Induces Cancer-Associated Fibroblast Differentiation of Mouse Bone Mesenchymal Stem Cells to Promote Tumor Growth.

Tumors recruit bone mesenchymal stem cells (BMSCs) to localize to tumor sites, which induces their conversion into cancer-associated fibroblasts (CAFs) that facilitate tumor progression. However, this process is poorly understood on the molecular level. In this study, we found that 4T1 breast cancer cells promoted the migration of BMSCs, and bFGF neutralizing antibody inhibited the migration of BMSCs induced by a tumor-conditioned medium. In addition, exogenous bFGF enhanced the migration of BMSCs in a dose-dependent manner in vitro. Furthermore, BMSCs promoted the proliferation of 4T1 tumor cells under BMSC-conditioned medium and in tumor xenograft model. Dramatically, BMSCs expressed CAF markers and produced collagen in the tumor microenvironment, and this transition was blocked by bFGF antibody. In addition, exogenous bFGF induced CAF differentiation of BMSCs. And bFGF increased phosphorylation of Erk1/2 and Smad3 in BMSCs and Erk inhibitor PD98059 was shown to block bFGF-induced Erk and Smad3 phosphorylation, suggesting that Erk/Smad3 signaling pathway involved in BMSC transdifferentiation induced by bFGF. Collectively, our results indicate that bFGF signaling plays indispensable roles in BMSC recruitment and transdifferentiation into CAFs and the consequent protumor effects, and targeting tumor stroma through bFGF inhibition maybe a promising strategy to suppress tumor progression.

Abstract B37: Targeting tumor-stroma metabolic symbiosis for head and neck cancer therapy

Abstract Despite aggressive therapies, head and neck squamous cell carcinoma (HNSCC), which affects 50,000 new patients annually in the United States, is associated with less than 50% 5-year survival. HNSCC tumors display increased glycolysis, even in the presence of oxygen. Consequently, there is an increase in lactic acid (LA) production. However, the effect of lactic acid in the tumor microenvironment and the mechanisms whereby HNSCC tumors survive in highly acidic conditions remain unknown. HNSCC consist of up to 80% tumor-associated fibroblasts (TAFs). We previously reported that activation of receptor tyrosine kinase, c-Met, by TAF-secreted hepatocyte growth factor (HGF) contributes to HNSCC progression (1,2). The mechanism associated with tumor-stroma metabolic symbiosis is not well understood. On this basis, we hypothesized that TAF-secreted HGF regulates HNSCC glycolysis. We demonstrate that HNSCC-secreted basic fibroblast growth factor (bFGF) induces oxidative phosphorylation (OXPHOS) in TAFs. In addition, bFGF regulates secretion of HGF from TAFs. TAF-secreted HGF increases HNSCC glycolysis and induces bFGF secretion from HNSCC. Thus, HNSCC and TAFs engage in reciprocal signaling through paracrine effects of HGF and bFGF. Inhibition of c-Met with small molecule inhibitor PF-02341066 or specific knockdown with c-Met siRNA decreased TAF-facilitated HNSCC glycolysis, lactic acid production and bFGF expression. In addition, inhibition of FGFR with small molecule inhibitor AZD-4547 decreased OXPHOS and HGF expression in TAFs. Inhibition of FGFR also reduced HNSCC-stimulated phosphorylation of p42/44 mitogen activated protein kinase, proliferation and migration in TAFs. Further, we tested the efficacy of AZD-4547 in combination with c-Met inhibitor PF-02341066 in mitigating TAF-induced HNSCC growth in vitro and in vivo. Combined treatment with AZD-4547 and PF-02341066 significantly inhibited TAF-induced proliferation of HNSCC in vitro compared to the vehicle control treated cells (p<0.001). Further, combined treatment significantly reduced growth of admixed HNSCC and TAF xenograft tumors (p<0.001). Our cumulative findings underscore the therapeutic potential of combinatorial treatment with PF-02341066 and AZD-4547 in HNSCC. The therapeutic approach developed in this study may be a feasible in HNSCC. 1. Wheeler SE, Shi H, Lin F, Dasari S, Bednash J, Thorne S, et al. Enhancement of head and neck squamous cell carcinoma proliferation, invasion, and metastasis by tumor-associated fibroblasts in preclinical models. Head & neck 2014;36(3):385-92. 2. Knowles LM, Stabile LP, Egloff AM, Rothstein ME, Thomas SM, Gubish CT, et al. HGF and c-Met participate in paracrine tumorigenic pathways in head and neck squamous cell cancer. Clinical cancer research : an official journal of the American Association for Cancer Research 2009;15(11):3740-50. Citation Format: Dhruv Kumar, Vikalp Vishwakarma, Jacob New, Wade Gutierrez, Hemant Chavan, Partha Kasturi, Ossama Tawfik, Douglas Girod, Bennett Van Houten, George Leef, Radhika Joshi, Shary Shelton, Jeffrey Straub, Yelizaveta Shnayder, Kiran Kakarala, Terance Tsue, Fangchen Lin, Sumana Dasari, Sufi Thomas. Targeting tumor-stroma metabolic symbiosis for head and neck cancer therapy. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr B37.

Abstract 4044: Rapamycin targets Interleukin 6 (IL-6) expression and suppresses endothelial cell invasion stimulated by tumor cells

Abstract Background: Previously we demonstrated that mTOR inhibitors have potent antiangiogenic and anti-lymphangiogenic effects in addition to their growth inhibitory effects in head and neck squamous cell carcinoma (HNSCC). Lymphatogenous spread is a significant problem and much more predominant in HNSCC than hematogenous spread. In this study we evaluated the effects of rapamycin on targeting tumor-stroma crosstalk in HNSCC. Methods: HNSCC tumor cells (FaDu), human blood microvascular endothelial cells (HMEC-1), and human lymphatic endothelial cells (HMEC-1A) were co-cultured in various combinations using transwell cell culture inserts to study tumor-stroma crosstalk and the effects of mTOR inhibitor rapamycin. Cell invasion was assessed using transwell inserts with an 8.0 μm pore size. Levels of various growth factors and cytokines in cell culture media were measured using Milliplex bead immunoassay (EMD Millipore) and ELISA assay (R&D Systems). Results: We found that conditioned media collected from tumor cells or co-culture with tumor cells significantly increased the invasiveness of lymphatic and blood vascular endothelial cells (p < 0.05), while there was no effect of conditioned media collected from endothelial cell cultures or co-culture with endothelial cells on tumor cell invasiveness. Conditioned media collected from tumor cell cultures increased the invasiveness of endothelial cells by almost two-fold. Next we evaluated the effects of rapamycin on the baseline and tumor cell stimulated (co-culture or conditioned media) invasiveness of endothelial cells. There was a significant effect of rapamycin on both baseline and tumor cell stimulated invasiveness of endothelial cells. While rapamycin had a moderate effect on the levels of several growth factors and cytokines tested (sVEGFR-1, HGF, FGF-2, TNF-alpha) there was a significant effect of the drug on the levels of IL-6. Importantly the level of IL-6 secreted in media increased significantly in tumor-endothelial cell co-culture compared to monocultures. Rapamycin showed only modest effect on the invasiveness of endothelial cells transfected with rapamycin-resistant mTOR as expected. There was no significant effect of rapamycin on secretion of IL-6 by tumor cells and endothelial cells transfected with rapamycin-resistant mTOR. Conclusions: HNSCC cells produce chemotactic stimuli that promote endothelial cell invasion toward tumor cells that can stimulate angio- and lymphagiogenesis. Rapamycin effectively reverted the stimulatory effect of cytokines secreted by tumor cells on endothelial cell. IL-6 is being evaluated as an important target in HNSCC and a potential biomarker of response to mTOR inhibitor therapy. Citation Format: Oleksandr Y. Ekshyyan, Xiaohua Rong, Tara Moore-Medlin, Xiaohui Ma, Jonathan Steven Alexander, Cherie-Ann O. Nathan. Rapamycin targets Interleukin 6 (IL-6) expression and suppresses endothelial cell invasion stimulated by tumor cells. [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 4044.

Abstract 1030: Targeting tumor-stroma metabolic symbiosis for head and neck cancer therapy

Abstract Head and neck squamous cell carcinoma (HNSCC) is an aggressive malignancy affecting 40,000 cases in the USA annually. Despite aggressive therapies HNSCC is associated with less than a 50% 5-year survival rate. Limited treatment options and high morbidity necessitate the development of new treatments. HNSCC tumors frequently consist of up to 80% tumor-associated fibroblasts (TAFs). We reported that tumor associated fibroblasts (TAFs) facilitate HNSCC progression. However, the molecular mechanisms that facilitate TAF-mediated tumor growth and metastasis remain unknown. Unlike normal cells, malignant cells often display increased glycolysis, even in the presence of oxygen; a phenomenon known as the Warburg effect. As a consequence, there is an increase in lactic acid (LA) production. It has been reported that HNSCC tumors have high LA levels that correlate with reduced survival. The mechanisms whereby HNSCC tumors survive in highly acidic conditions remain unknown. We previously reported that TAF-secreted hepatocyte growth factor (HGF) facilitates HNSCC progression. Here we demonstrate that TAF-secreted HGF regulates HNSCC glycolysis and increases basic fibroblast growth factor (bFGF) secretion from HNSCC. Further, HNSCC-secreted bFGF regulates mitochondrial oxidative phosphorylation (OXPHOS) in TAFs. Inhibition of c-Met by PF-02341066 or knockdown by siRNA decreases glycolysis and bFGF expression in HNSCC. In addition, inhibition of FGFR by AZD-4547 decreased OXPHOS and HGF expression in TAFs. Thus, HNSCC and TAFs engage in reciprocal signaling through paracrine effects of HGF and bFGF. Combined treatment with AZD-4547 and PF-02341066 significantly inhibited TAF-induced proliferation of HNSCC in vitro compared to the vehicle control treated cells. For the first time, we tested FGFR inhibitor AZD-4547 in combination with c-Met inhibitor PF-02341066 both in vitro and in vivo xenograft models. The combination treatment significantly inhibited proliferation of HNSCC in vitro and effectively reduced HNSCC tumor growth compared to either agent alone in vivo (p<0.001). Our cumulative findings underscore the therapeutic potential of combinatorial treatment with PF-02341066 and AZD-4547 in HNSCC. Citation Format: Dhruv Kumar, Vikalp Vishwakarma, Jacob New, Radhika Joshi, Fangchen Lin, Sumana Dasari, Wade Gutierrez, Hemant Chavan, Ossama Tawfik, Shary Shelton, Yelizaveta Shnayder, Kiran Kakarala, Terance Tsue, Douglas Girod, Bennett Van Houten, Partha Kasturi, Sufi M. Thomas. Targeting tumor-stroma metabolic symbiosis for head and neck cancer therapy. [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 1030.

Hypoxia Enhances Tumor-Stroma Crosstalk that Drives the Progression of Hepatocellular Carcinoma.

Crosstalk between tumor cells and their microenvironment plays a crucial role in the progression of hepatocellular carcinoma (HCC). Hypoxia, a common feature of advanced HCC, has been shown to modulate the evolution of the tumor microenvironment. In this study, we investigated the effect of hypoxia on tumor-stroma crosstalk in HCC. Human HCC cell lines (Huh-BAT, SNU-475) were cocultured with an activated human hepatic stellate cell line (HSCs; LX-2) under either normoxic or hypoxic conditions. Cell growth was evaluated with the MTS assay. Apoptotic signaling cascades were assessed by immunoblot analysis. Expression of CD31 and phosphorylated (p-) Akt in HCC tissues was detected by immunohistochemistry. Coculturing HCC cells with HSCs under hypoxic conditions enhanced their proliferation, migration, and resistance to bile acid (BA)-induced apoptosis compared to coculturing under normoxic conditions. Under hypoxia, of various HSC-derived growth factors, PDGF-BB was the most up-regulated, leading to the activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in HCC cells. Immunohistochemical study also revealed that p-Akt was highly expressed in hypoxic, hypovascular HCC as compared to hypervascular HCC. Neutralizing antisera to PDGF-BB or a PI3K inhibitor attenuated the proliferation of HCC cells cocultured with HSCs, and sensitized HCC cells to BA-induced apoptosis, especially under hypoxic conditions. In conclusion, hypoxic HSC-derived PDGF-BB stimulates the proliferation of HCC cells through activation of the PI3K/Akt pathway, while the inhibition of PDGF-BB or PI3K/Akt pathways enhances apoptotic cell death. Targeting tumor-stroma crosstalk might be a novel therapy in the management of human HCCs.

Targeting tumor-stroma crosstalk: the example of the NT157 inhibitor.

Recent clinical research has provided evidence that cancer progression and therapy resistance is driven not only by tumor's genetic profile but also by complex paracrine interactions within the tumor microenvironment (TME). The role of TME in modulating tumor drug sensitivity is increasingly recognized and targeting TME has been the focus of novel therapeutic approaches. Two recent reports show that a new anti-cancer drug, the inhibitor NT157 has the potential to inhibit IGF-1R and STAT3 signaling pathways in cancer cells and stroma cells of TME leading to a decrease in cancer cell survival.

Adoptive therapy with CAR redirected T cells: the challenges in targeting solid tumors.

Recent spectacular success in the adoptive cell therapy of leukemia and lymphoma with chimeric antigen receptor (CAR)-modified T cells raised the expectations that this therapy may be efficacious in a wide range of cancer entities. The expectations are based on the predefined specificity of CAR T cells by an antibody-derived binding domain that acts independently of the natural T-cell receptor, recognizes targets independently of presentation by the major histocompatibility complex and allows targeting toward virtually any cell surface antigen. We here discuss that targeting CAR T cells toward solid tumors faces certain circumstances critical for the therapeutic success. Targeting tumor stroma and taking advantage of TRUCK cells, in other words, CAR T cells with inducible release of a transgenic payload, are some strategies envisaged to overcome current limitations in the near future.

Combretastatin A4-phosphate and its potential in veterinary oncology: a review.

For many years, research on anticancer therapy has focussed almost exclusively on targeting cancer cells directly, to selectively kill them or restrict their growth. But limited advances in this strategy have led researchers to shift their attention to other potential targets. Active research is now on-going on targeting tumour stroma. Vascular disrupting agents (VDAs) appear a promising class of anticancer drugs that are currently under investigation as a sole or combined therapy in human cancer patients. This article will briefly touch on the history and biology of combretastatin A4-phosphate (CA4P) as a typical example of VDAs and will concentrate on the side effects that can be expected when used in veterinary patients. Particularly, the pathogenesis of these side effects and how they may be prevented and/or treated will be discussed. The purpose of this article is to illustrate the potentials of CA4P as anticancer therapy in veterinary oncology patients.

Abstract 2691: Smo-targeted sonic hedgehog signaling inhibitor enhances therapeutic antibody deposition and efficacy in a patient-derived pancreatic ductal adenocarcinoma model

Abstract Tumor stroma supports growth, invasion, and treatment resistance of pancreatic ductal adenocarcinoma (PDAC), and in conjunction with hypovascularity, constitutes a barrier that minimizes tumor cell drug exposure. Targeting tumor stroma is an attractive strategy in PDAC, and Smo-binding inhibitors are reported to mediate stromal thinning and increased microvessel density in PDAC models. No information exists as to the effect of sHHI upon deposition of macromolecular therapeutic agents such as monoclonal antibodies (mAb). Therefore we investigated effects of sHHI LDE225 upon tumor vascularity, mAb deposition, and mAb therapeutic efficacy in a patient-derived xenograft (PDX) model of PDAC in SCID mice. PDAC tumor #18269 was established in SCID mice and has retained abundant stroma and low microvessel density reminiscent of the original patient tumor. It expresses EGF receptor. Tumor-bearing mice were dosed orally with LDE225 (40 mg/kg) for 10 days, and pharmacodynamic biomarkers of sHHI effect were quantified. Mouse-specific TaqMan probes demonstrated high Gli1 expression in stromal cells, which was deeply suppressed within 3 days of sHHI dosing. Human-specific probes showed little Gli1 expression in tumor cells and no effect of sHHI treatment. Over 10 days of sHHI treatment, tumor microvessel density did not change significantly (based on CD31 staining), but the fraction of functional vessels increased significantly by day 7 (based on staining with fluorescent Lycopersicon esculentum lectin injected IV prior to tumor harvest). Fluorescently labeled mAbs that were tumor-targeted (cetuximab; anti-EGFR) or non-targeted (anti-topotecan) were co-injected on d7 of sHHI treatment. Compared to untreated controls, tumor exposure (AUC) of cetuximab more than doubled, and was observed to distribute to regions of the tumor enriched in tumor cells. Deposition of non-targeted mAb also was increased relative to controls, but distributed more to stromal areas than tumor cell areas. To investigate whether the enhanced deposition of cetuximab mediated by sHHI pretreatment would enhance efficacy, cetuximab was administered on d 5, 8, 11 of a 10-day sHHI or vehicle (control) regimen. This sequence was repeated 6 times, with an inter-cycle gap of 5 days. Rituximab (anti-human CD20) was the non-targeted control. Cetuximab alone showed no therapeutic benefit. However, cetuximab combined with sHHI suppressed tumor progression for more than 80 days, and median time to study endpoint was more than 250% longer than for all other treatment groups except sHHI-alone, which mediated a 30% increase. Conclusions: increased perfusion and vascular permeability mediated by sHHI pretreatment permits access of therapeutic mAb to otherwise inaccessible regions of the tumor interior, and reveals anti-tumor activity of a mAb that previously failed clinically for PDAC treatment. Citation Format: Jun Wang, Yang Qu, Rose Pitoniak, Sheryl A. Trueman-Fatallah, Bonnie L. Hylander, Elizabeth A. Repasky, Wen Wee Ma, Robert M. Straubinger. Smo-targeted sonic hedgehog signaling inhibitor enhances therapeutic antibody deposition and efficacy in a patient-derived pancreatic ductal adenocarcinoma model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2691. doi:10.1158/1538-7445.AM2014-2691