Cancer Cells In Tumor Microenvironment Research Articles

PB1407 Colonization of Fibrin Clot Formed by Cancer Cells in Tumor Microenvironment. A Mechanism Potentially Related with Resistance to the Anticancer Treatment

PB1407 Colonization of Fibrin Clot Formed by Cancer Cells in Tumor Microenvironment. A Mechanism Potentially Related with Resistance to the Anticancer Treatment

The effect of diet and nutrition on T cell function in cancer.

Cancer can be considered one of the most threatening diseases to human health, and immunotherapy, especially T-cell immunotherapy, is the most promising treatment for cancers. Diet therapy is widely concerned in cancer because of its safety and fewer side effects. Many studies have shown that both the function of T cells and the progression of cancer can be affected by nutrients in the diet. In fact, it is challenging for T cells to infiltrate and eliminate cancer cells in tumor microenvironment, because of the harsh metabolic condition. The intake of different nutrients has a great influence on the proliferation, activation, differentiation and exhaustion of T cells. In this review, we summarize the effects of typical amino acids, lipids, carbohydrates and other nutritional factors on T cell functions and provide future perspectives for dietary treatment of cancer based on modifications of T cell functions.

Abstract 6379: Dipeptidyl peptidase-4 inhibitor impairs the outcomes of patients with type 2 diabetes mellitus after curative resection for colorectal cancer

Abstract Background: Type2 diabetes mellitus(T2DM) is a risk factor for cancer. Recent studies have shown that DPP-4 inhibitor(DPP-4i) can either promote or suppress cancer progression. However, the detailed mechanisms remain unknown. Here, in this study, we investigated the effect of DPP-4i on tumor microenvironment and its effect on the prognosis of cancer patients. Method: We retrospectively examined the outcome of colorectal cancer (CRC) patients with T2DM who received curative surgery in Jichi Medical University Hospital and asked the impact of DPP-4i intake on their outcome. In addition, we performed immunohistochemistry to examine the phenotypes of TIL, TAM and epithelial-mesenchymal transition (EMT) of cancer cells in surgically removed CRC tissues in 40 CRC patients who had taken DPP-4i and propensity score-matched 40 patients who had not. Results: A total of 1696 patients underwent curative colectomy from April 2010 to March 2020. Among them, 260 patients had T2DM at the time of surgery, and 135 patients had been treated with drugs including DPP-4i. The postoperative disease-free survival rate (DFS) was significantly worse in the DPP-4i intake group compared with non-intake group (5 year DFS 18.5% vs 5.4%, HR=2.0, p<0.05). The number of Zeb1-positive tumor cells significantly increased in DPP-4i intake group. (Median(M)=29.0 (0-189)/mm2 vs 9.0 (0-71)/mm2, p<0.01). The number of CD3 (+) TIL in DPP-4i intake group was Median(M)=277.4(min 121.6-max 523.2)/mm2 which was significantly lower than those in non-intake group (M= 319.6, min 493.0-max 823.6/mm2). CD8(+) TIL in DPP-4i intake was reduced more significantly than in non-intake group (M=187.6, min 67.8-max 347.4/mm2 vs M=336.8, min 200.2-max 588.4/mm2, p<0.05) with less CD8/CD3 ratio (61.2% vs 67.1%, p<0.05). On the other hand, the density of CD68(+)CD163(+) TAM was significantly higher(M=202.6, min 122.8-max 257.0/mm2 vs M=126.6, min 94.8-max 247.6/mm2, p<0.05) in DPP-4i intake group. Conclusion: DPP-4i increases the number of M2-type TAM while decreases the number of effector TIL and promote EMT of cancer cells in tumor microenvironment, which might lead to the poor outcome of the patients with CRC. Citation Format: Akira Saito, Hideyuki Ohzawa, Yuki Kaneko, Kohei Tamura, Yurie Futoh, Kazuya Takahashi, Yuki Kimura, Mineyuki Tojo, Rie Kawashima, Hideyo Miyato, Naohiro Sata, Joji Kitayama. Dipeptidyl peptidase-4 inhibitor impairs the outcomes of patients with type 2 diabetes mellitus after curative resection for colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6379.

Remodeling metabolic fitness: Strategies for improving the efficacy of chimeric antigen receptor T cell therapy.

The dramatic success of adoptive transfer of engineered T cells expressing chimeric antigen receptor (CAR-T) has been achieved with effective responses in some relapsed or refractory hematologic malignancies, which is not yet met in solid tumors. The efficacy of CAR-T therapy is associated with its fate determination and their interaction with cancer cells in tumor microenvironment (TME), which is closely correlated with T cell metabolism fitness. Indeed, modulating T cell metabolism reprogramming has been proven crucial for their survival and reinvigorating antitumor immunity, and thus is considered as a promising strategy to improve the clinical performance of CAR-T cell therapy in difficult-to-treat cancers. This review briefly summarizes the T cell metabolic profiles and key metabolic challenges it faces in TME such as nutrient depletion, hypoxia, and toxic metabolites, then emphatically discusses the potential strategies to modulate metabolic properties of CAR-T cells including improving CARs construct design, optimizing manufacture process via addition of exogenous cytokines or targeting specific signaling pathway, manipulating ROS levels balance or relieving the unfavorable metabolic TME including adaptation to hypoxia and blocking inhibitory effect of toxic metabolites, eventually strengthening the anti-tumor response.

Prognostic and predictive value of a metabolic risk score model in breast cancer: an immunogenomic landscape analysis.

Breast cancer is a kind of malignant tumor that occurs in breast tissue, which is the most common cancer in women. Cellular metabolism is a critical determinant of the viability and function of cancer cells in tumor microenvironment. In this study, based on the gene expression profile of metabolism-related genes, the prognostic value of 20 metabolic pathways in patients with breast cancer was identified. A universal risk stratification signature that relies on 20 metabolic pathways was established and validated in training cohort, two testing cohorts and The Cancer Genome Atlas pan cancer cohort. Then, the relationship between metabolic risk score subtype, prognosis, immune infiltration level, cancer genotypes and their impact on therapeutic benefit were characterized. Results demonstrated that the patients with the low metabolic risk score subtype displayed good prognosis, high level of immune infiltration and exhibited a favorable response to neoadjuvant chemotherapy and immunotherapy. Taken together, the work presented in this study may deepen the understanding of metabolic hallmarks of breast cancer, and may provide some valuable information for personalized therapies in patients with breast cancer.

A stromal and immune cell infiltration-based score model predicts prognosis and chemotherapy effect in colorectal cancer

The stromal and immune cells crosstalk with cancer cells in tumor microenvironment, but few studies have fully considered the overall landscape of the infiltrating stromal and immune cells in colorectal cancer. We enrolled 1836 colorectal cancer patients and divided them into the training, validation and test cohorts. 64 stromal and immune cells were quantified in each primary colorectal cancer tissue by estimating gene expression data using xCell algorithm. Univariate, LASSO and multivariate Cox regression analyses were subsequently employed to establish a stromal and immune score prognostic model based on 13 potential cell biomarkers. Patients of the three cohorts were divided into the high- and low-risk groups according to the cutoff value. Compared with the low-risk group, high-risk group showed significant shorter survival, worse clinicopathologic outcomings, higher cancer-related expressions and more active epithelial-mesenchymal transformation. 5-Fu and FUFOL chemotherapy regimens made the low-risk patients gain significant survival advantage, while none chemotherapy regimens benefited the high-risk group, which may benefit from immune checkpoint inhibitors. The nomogram combining the stromal and immune score with standard TNM staging system showed better predictive accuracy than TNM stage alone. The stromal and immune cell infiltration-based score model can effectively and efficiently predict the prognosis and chemotherapy effect in colorectal cancer.

Abstract 2693: Macrophage-derived endotrophin supports tumor migration potentials in thyroid cancer

Abstract Endotrophin (ETP), a cleaved fragment of the C5 domain of the Type VI collagen α3 (Col6α3), has been shown to play pro-tumorigenic roles in breast and liver cancers. However, the ETP actions in tumor microenvironment (TME) is still undetermined. This study aimed to investigate the role and the mechanism of ETP in macrophage-enriched thyroid cancer TMEs. First, the expression of ETP on various human thyroid tissues was studied. Immunohistochemical staining showed that the ETP was expressed in papillary (PTC) or anaplastic (ATC) thyroid cancer tissues but not in benign adenoma or autoimmune thyroiditis. Among 146 PTCs, tumors were divided into two groups according to their ETP expression, ETPlow and ETPHigh. Tumor size was bigger and LN metastasis rates were higher in ETPHigh than ETPlow group. Interestingly, the ETP expression showed positive correlations with the CD163-positive macrophages in thyroid tumors. To clarify the origin of ETP in TME of thyroid cancer, xenograft tumor from FRO (ATC) cells was co-stained with anti-ETP and anti-CD11b antibodies. Immunofluorescent staining showed that the expression of ETP and CD11b-postive macrophages were co-localized in the peritumoral area. Moreover, CD163+ cells, as a marker of M2-type macrophage, were co-localized with ETP+ cells. Additionally, human monocytic THP-1 cells were treated with conditioned media (CM) from FRO or BCPAP cells (designated FRO-CM or BCPAP-CM) and demonstrated that ETP expression was more up-regulated in the FRO-CM or BCPAP-CM treated group than in the control group. Collectively, ETP produced from M2-type macrophages in thyroid cancer microenvironments. Next, the pro-tumorigenic functions of ETP has been studied. CMs from co-cultures of FRO or BCPAP cells with THP-1 cells were harvested and treated to FRO or BCPAP cells. Treatment of CMs from co-cultures increased cell migration potentials than that of the single cell alone, and these effects were reduced by anti-ETP neutralizing antibody, indicating that ETPs play essential role in macrophage-induced tumor cell migration potentials. Moreover, MMP-9 and MMP-14, the candidates of Col6α3 protease to produce ETP were increased in THP-1 cells by treatment of CM. Additionally, treatment of CMs from MMP-9 or MMP-14 inhibitor-treated co-cultures of FRO and THP-1 cells decreased cancer cells migration potentials than the control CMs, and these effects were recovered by treatment of ETP. Finally, the RNA-seq dataset of human thyroid cancer showed that higher expressions of ETP positively correlated with macrophage-related genes such as CD163 and MMPs including MMP-9 and MMP-14. In conclusion, macrophage contributes ETP productions by modulating MMP expressions and ETP supports pro-metastatic potentials of human thyroid cancer cells in TMEs. Thus ETP can be a good therapeutic target for macrophage-enriched advanced thyroid cancers Citation Format: Hyo Shik Shin, Hana Kim, Young Shin Song, Hyun Jin Sun, Young Mi Whang, Jiyoung Park, Do Joon Park, Young Joo Park, Sun Wook Cho. Macrophage-derived endotrophin supports tumor migration potentials in thyroid cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2693.

Macrophage-Derived Endotrophin Supports Tumor Migration Potentials in Thyroid Caner

Abstract Endotrophin (ETP), a cleaved fragment of the C5 domain of the Type VI collagen α3 (Col6α3), has been shown to play pro-tumorigenic roles in breast and liver cancers. However, the ETP actions in tumor microenvironment (TME) is still undetermined. This study aimed to investigate the role and the mechanism of ETP in macrophage-enriched thyroid cancer TMEs. First, the expression of ETP on various human thyroid tissues was studied. Immunohistochemical staining showed that the ETP was expressed in papillary (PTC) or anaplastic (ATC) thyroid cancer tissues but not in benign adenoma or autoimmune thyroiditis. Among 146 PTCs, tumors were divided into two groups according to their ETP expression, ETPlow and ETPHigh. Tumor size was bigger and LN metastasis rates were higher in ETPHigh than ETPlow group. Interestingly, the ETP expression showed positive correlations with the CD163-positive macrophages in thyroid tumors. To clarify the origin of ETP in TME of thyroid cancer, xenograft tumor from FRO (ATC) cells was co-stained with anti-ETP and anti-F4/80 antibodies. Immunofluorescent staining showed that the expression of ETP and F4/80-postive macrophages were co-localized in the peritumoral area. Additionally, human monocytic THP-1 cells were treated with conditioned media (CM) from FRO or BCPAP cells (designated FRO-CM or BCPAP-CM) and demonstrated that ETP expression was more up-regulated in the FRO-CM or BCPAP-CM treated group than in the control group. Collectively, ETP produced from macrophages in thyroid cancer microenvironments. Next, the pro-tumorigenic functions of ETP has been studied. CMs from co-cultures of FRO or BCPAP cells with THP-1 cells were harvested and treated to FRO or BCPAP cells. Treatment of CMs from co-cultures increased cell migration potentials than that of the single cell alone, and these effects were reduced by anti-ETP neutralizing antibody, indicating that ETPs play essential role in macrophage-induced tumor cell migration potentials. Moreover, MMP-9 and MMP-14, the candidates of Col6α3 protease to produce ETP were increased in THP-1 cells by treatment of CM. Additionally, treatment of CMs from MMP-9 inhibitor-treated co-cultures of FRO and THP-1 cells decreased cancer cells migration potentials than the control CMs. Finally, the RNA-seq dataset of human thyroid cancer showed that higher expressions of ETP positively correlated with macrophage-related genes such as CD163 and MMPs including MMP-9 and MMP-14. In conclusion, macrophage contributes ETP productions by modulating MMP expressions and ETP supports pro-metastatic potentials of human thyroid cancer cells in TMEs. Thus ETP can be a good therapeutic target for macrophage-enriched advanced thyroid cancers.

Metabolites in the Tumor Microenvironment Reprogram Functions of Immune Effector Cells Through Epigenetic Modifications.

Cellular metabolism of both cancer and immune cells in the acidic, hypoxic, and nutrient-depleted tumor microenvironment (TME) has attracted increasing attention in recent years. Accumulating evidence has shown that cancer cells in TME could outcompete immune cells for nutrients and at the same time, producing inhibitory products that suppress immune effector cell functions. Recent progress revealed that metabolites in the TME could dysregulate gene expression patterns in the differentiation, proliferation, and activation of immune effector cells by interfering with the epigenetic programs and signal transduction networks. Nevertheless, encouraging studies indicated that metabolic plasticity and heterogeneity between cancer and immune effector cells could provide us the opportunity to discover and target the metabolic vulnerabilities of cancer cells while potentiating the anti-tumor functions of immune effector cells. In this review, we will discuss the metabolic impacts on the immune effector cells in TME and explore the therapeutic opportunities for metabolically enhanced immunotherapy.

Secretion of bispecific protein of anti-PD-1 fused with TGF-β trap enhances antitumor efficacy of CAR-T cell therapy

Despite the remarkable success of chimeric antigen receptor-modified T (CAR-T) cell therapy for blood malignancies, the clinical efficacy of this novel therapy in solid tumor treatment is largely limited by the immunosuppressive tumor microenvironment (TME). For instance, immune checkpoints (e.g., programmed cell death protein 1 [PD-1]/programmed death ligand 1 [PD-L1]) in TME play an important role in inhibiting T cell proliferation and functions. Transforming growth factor β (TGF)-β secreted by cancer cells in TME induces regulatory T cells (Tregs) and inhibits cytotoxic T cells. To overcome the inhibitory effect of immune checkpoints, we have previously engineered CAR-T cells to secrete anti-PD-1 to block the PD-1/PD-L1 pathway activity, a step demonstrating superior antitumor efficacy compared with conventional CAR-T cells. In this study, we engineered CAR-T cells that secrete bispecific trap protein co-targeting PD-1 and TGF-β, with the aim of further improving antitumor immunity. Compared with conventional CAR-T cells and anti-PD-1-secreting CAR-T cells, data from in vitro and in vivo experiments showed that CAR-T cells with trap protein secretion further attenuated inhibitory T cell signaling, enhanced T cell persistence and expansion, and improved effector function and resistance to exhaustion. In the xenograft mouse model, CAR-T cells with trap protein secretion exhibited significantly enhanced antitumor immunity and efficacy. With these observations, we demonstrate the potential of trap protein self-secreting CAR-T cells as a potent therapy for solid tumors.

Tumor Metabolic Reprogramming by Adipokines as a Critical Driver of Obesity-Associated Cancer Progression.

Adiposity is associated with an increased risk of various types of carcinoma. One of the plausible mechanisms underlying the tumor-promoting role of obesity is an aberrant secretion of adipokines, a group of hormones secreted from adipose tissue, which have exhibited both oncogenic and tumor-suppressing properties in an adipokine type- and context-dependent manner. Increasing evidence has indicated that these adipose tissue-derived hormones differentially modulate cancer cell-specific metabolism. Some adipokines, such as leptin, resistin, and visfatin, which are overproduced in obesity and widely implicated in different stages of cancer, promote cellular glucose and lipid metabolism. Conversely, adiponectin, an adipokine possessing potent anti-tumor activities, is linked to a more favorable metabolic phenotype. Adipokines may also play a pivotal role under the reciprocal regulation of metabolic rewiring of cancer cells in tumor microenvironment. Given the fact that metabolic reprogramming is one of the major hallmarks of cancer, understanding the modulatory effects of adipokines on alterations in cancer cell metabolism would provide insight into the crosstalk between obesity, adipokines, and tumorigenesis. In this review, we summarize recent insights into putative roles of adipokines as mediators of cellular metabolic rewiring in obesity-associated tumors, which plays a crucial role in determining the fate of tumor cells.

Rational designing of glyco-nanovehicles to target cellular heterogeneity.

The aberrant expression of endocytic epidermal growth factor receptors (EGFRs) in cancer cells has emerged as a key target for therapeutic intervention. Here, we describe for the first time a state-of-the-art design for a heparan sulfate (HS) oligosaccharide-based nanovehicle to target EGFR-overexpressed cancer cells in cellular heterogeneity. An ELISA plate IC50 inhibition assay and surface plasma resonance (SPR) binding assay of structurally well-defined HS oligosaccharides showed that 6-O-sulfation (6-O-S) and 6-O-phosphorylation (6-O-P) of HS tetrasaccharides significantly enhanced EGFR cognate growth factor binding. The conjugation of these HS ligands to multivalent fluorescent gold nanoparticles (AuNPs) enabled the specific and efficient targeting of EGFR-overexpressed cancer cells. In addition, this heparinoid-nanovehicle exhibited selective homing to NPs in cancer cells in three-dimensional (3D) coculture spheroids, thus providing a novel target for cancer therapy and diagnostics in the tumor microenvironment (TME).

Effect of macrophages on biological function of ovarian cancer cells in tumor microenvironment in vitro.

To investigate the influence of two types of tumor-associated macrophages (TAMs) on the biological function of human ovarian cell lines in vitro. (1) M2 macrophage release was induced by IL-4, and M1 macrophage release by phorbol myristate acetate (PMA) in vitro. Flow cytometry was used to distinguish these two types; (2) transwell culture system was used to establish a non-contact co-culture model of macrophage and ovarian cancer cells (SKOV3, HEY, HO8910 and A2780) in vitro. The microenvironment of ovarian cancer was simulated in vitro. (3) The proliferation, apoptosis, migration and invasion of ovarian cancer cells SKOV3, HEY, HO8910 and A2780 were analyzed after co-culture. Their proliferation was detected by CCK8 method, apoptosis by flow cytometry, Annexin V-FITC/PI double staining, invasion by Transwell assay, and migration by wound healing test. (1) IL-4-induced macrophages (M2) overexpressed CD163, and PMA-induced macrophages (M1) overexpressed HLA-DR. After co-culturing primary macrophages with ovarian cancer cells (SKOV3, HEY, HO8910, A2780), macrophage CD163 was highly expressed. (2) Proliferation and apoptosis of ovarian cancer cells (SKOV3, HEY, HO8910, A2780): the proliferation of ovarian cancer cells in M2 co-culture group increased compared to that in M1 co-culture group and primary co-culture group (p < 0.05); the apoptosis of ovarian cancer cells in M2 co-culture group decreased compared to that in M1 co-culture group and primary co-culture group (p < 0.05). (3) Migration and invasion of ovarian cancer cells (SKOV3, HEY, HO8910, A2780): the invasion of ovarian cancer cells in M2 co-culture group increased compared to that in M1 co-culture group and primary co-culture group (p < 0.05); the migration of ovarian cancer cells in M2 co-culture group increased compared to that in M1 co-culture group and the primary co-culture group (p < 0.05). In the simulated in vitro tumor microenvironment, co-cultured ovarian cancer cells polarized macrophages to the M2 phenotype. Furthermore, M2 macrophages enhanced the proliferation, invasion and migration, and inhibited the apoptosis of ovarian cancer cells.

Exosomes released from pancreatic cancer cells enhance angiogenic activities via dynamin-dependent endocytosis in endothelial cells in vitro

Pancreatic cancer has the lowest 5 year survival rate among all cancers. Several extracellular factors are involved in the development and metastasis of pancreatic cancer to distant organs. Exosomes are lipid-bilayer, membrane-enclosed nanoparticles that are recognised as important mediators of cell-to-cell communications. However, the role of exosomes released from pancreatic cancer cells in tumour micro-environment remains unknown. Here, we show that exosomes released from pancreatic cancer PK-45H cells activate various gene expressions in human umbilical vein endothelial cells (HUVECs) by in vitro analyses. In addition, these exosomes released from PK-45H cells promote phosphorylation of Akt and ERK1/2 signalling pathway molecules and tube formation via dynamin-dependent endocytosis in HUVECs. Our findings suggested that exosomes released from pancreatic cancer cells may act as a novel angiogenesis promoter.

Abstract 5212: The inhibitory effect of iron control on breast cancer cells in tumor microenvironment

Abstract Background: Iron is an essential element for both normal and cancer cells, and it is well known that iron depletion leads to G1-S arrest and apoptosis. Iron depletion is also known to reduce serum hemoglobin and oxygen supply to the tissue, which may induce angiogenesis. On the other hand, it is reported that hypoxia mediates epithelial-mesenchymal transition (EMT) and cancer cell metastasis with angiogenesis. In addition, it is thought that antitumor autoimmune response relates to suppression of EMT, and we investigated previously it with clinical samples. In this study, we examined the mechanism of iron control therapy in breast cancer based on hypoxia, EMT and immune microenvironment. Material and Methods: Human breast cancer cell lines MDA-MB-231 (triple-negative breast cancer), MCF-7 (luminal type) and OCUB-1 (HER2-enriched type), and iron chelator Deferoxamine (DFO) were used in the present study. The effect of proliferation and migration of breast cancer cells by DFO was determined using MTT assay and wound healing assay. We also examined the influence of cell cycle by DFO using flow cytometry. Furthermore, we investigated the relationship between iron depletion of breast cancer cells and hypoxia, EMT and immune microenvironment using RT-PCR. We produced subcutaneous xenografts of mice, and examined the change in tumor sizes by administration of DFO. Results: The iron-depleted condition suppressed breast cancer cell proliferation and migration. In cell cycle analysis, DFO increased the population of the G0-G1 phase. In addition, iron depletion induced hypoxia and angiogenesis. Also, N-cadherin and PD-L1 expression of breast cancer cells were increased by iron-depleted condition. Subcutaneous tumors in the DFO administration group were suppressed tumor growth in vivo. Conclusion: Iron control by DFO showed the effect of tumor suppression, and suggested the possibility of novel treatment for patients with breast cancer. In addition, this mechanism related to hypoxia, EMT and immune microenvironment. Citation Format: Wataru Goto, Shinichiro Kashiwagi, Koji Takada, Yuka Asano, Tsutomu Takashima, Satoru Noda, Naoyoshi Onoda, Kosei Hirakawa, Masaichi Ohira. The inhibitory effect of iron control on breast cancer cells in tumor microenvironment [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 5212.

The role of sphingosine-1-phosphate in the tumor microenvironment and its clinical implications.

Elucidating the interaction between cancer and non-cancer cells, such as blood vessels, immune cells, and other stromal cells, in the tumor microenvironment is imperative in understanding the mechanisms underlying cancer progression and metastasis, which is expected to lead to the development of new therapeutics. Sphingosine-1-phosphate is a bioactive lipid mediator that promotes cell survival, proliferation, migration, angiogenesis/lymphangiogenesis, and immune responsiveness, which are all factors involved in cancer progression. Sphingosine-1-phosphate is generated inside cancer cells by sphingosine kinases and then exported into the tumor microenvironment. Although sphingosine-1-phosphate is anticipated to play an important role in the tumor microenvironment and cancer progression, determining sphingosine-1-phosphate levels in the tumor microenvironment has been difficult due to a lack of established methods. We have recently developed a method to measure sphingosine-1-phosphate levels in the interstitial fluid that bathes cancer cells in the tumor microenvironment, and reported that high levels of sphingosine-1-phosphate exist in the tumor interstitial fluid. Importantly, sphingosine-1-phosphate can be secreted from cancer cells and non-cancer components such as immune cells and vascular/lymphatic endothelial cells in the tumor microenvironment. Furthermore, sphingosine-1-phosphate affects both cancer and non-cancer cells in the tumor microenvironment promoting cancer progression. Here, we review the roles of sphingosine-1-phosphate in the interaction between cancer and non-cancer cells in tumor microenvironment, and discuss future possibilities for targeted therapies against sphingosine-1-phosphate signaling for cancer patients.

The potential roles of vesicle-enclosed miRNAs in communication between macrophages and cancer cells in tumor microenvironment.

Functional microRNA (miRNA) molecules are transported in extracellular vesicles among tumor cells and cells of the immune system. Macrophages as integral components of tumor microenvironment are known as potential contributors to tumor growth and progression. We searched for studies which could provide a direct link between the particular miRNAs transported between cancer cells and macrophages and experimental evidence of subsequent alterations in biological functions of target cells. The validated targets of such microRNAs were found using miRWalk database. These targets were further subjected to analysis by DAVID (Database for Annotation, Visualization and Integrated Discovery) to find the most prominent cellular events that could be potentially regulated in macrophages by miRNAs originated from cancer cells and vice versa. We found that the 5 miRNAs (let-7b, miR-21, miR-29a, miR-222-3p, miR-451) derived from cancer cells may together regulate 2304 target genes in macrophages. The genes involved in regulation of apoptosis, regulation of gene expression and protein transport were significantly overrepresented in this set. Four of the five sets of target genes for these individual miRNAs overlap in MYC oncogene. MYC dependent transcriptional program is responsible for cell cycle entry and regulates the inflammatory response in macrophages.Both miRNAs for which the functional transports from macrophages to cancer cells were experimental proven (miR-223, miR-142-3p) target total 684 genes including some well-known tumor suppressors like TP53 or APC. Suppression of tumor suppressor genes by miRNAs derived from macrophages may eventually contribute to cancer cell proliferation.Due to the complexity of tumor microenvironment, the altered expression profiles of its components affected by miRNA uptake from extracellular vesicles could contribute to the outcome of carcinogenesis therefore the vesicular transport of miRNAs should be studied more extensively in this context.

Abstract 4149: Direct immune cell contact to basal-like triple negative breast cancer cells evokes downregulation of EGFR and PD-L1

Abstract BACKGROUND: We previously reported that direct co-culture of triple negative breast cancer cell line MDA-MB-231 and immune cells results in reduction of EGFR expression on cell surface of MDA-MB-231 (AACR 2015 #2349). However, a role of reduction of EGFR on MDA-MB-231 via co-culture with immune cells still remains unclear. Therefore, we evaluated a role of reduction of EGFR on MDA-MB-231 at the immunological point of view by testing expression of immune related genes including PD-L1. METHODS: In order to verify the importance of direct immune cell contact to breast cancer cell, MDA-MB-231 cells were co-cultured directly or indirectly with THP-1 cells (human monocytic cell line) at 1:50 cellular ratios. In order to study indirect co-culture assay, we used cell culture insert to avoid direct cancer cell-immune cell contact. We analyzed gene expression by quantitative real time PCR and membrane protein expression by flow cytometry of EGFR, also other HER family on MDA-MB-231 which is directly or indirectly co-cultured with THP-1. We also evaluated the expression of immune related genes including PD-L1. RESULTS: Both mRNA and protein level of EGFR on MDA-MB-231 cells directly co-cultured with THP-1 were significantly decreased as compared to those with indirectly co-cultured MDA-MB-231 cells. There are no significant differences in EGFR expression between indirectly co-cultured MDA-MB-231 cells and control MDA-MB-231 cells. Importantly, PD-L1 expression on MDA-MB-231 cells directly co-cultured with THP-1 was significantly decreased as compared to that with indirectly co-cultured MDA-MB-231 cells. CONCLUSION: It has been reported that PD-L1 expression in cancers is regulated by phosphatidylinositol 3-kinase (PI3K) and Akt signaling. Thus, our findings may give a novel insight on regulation of PD-L1 expression on cancer cells in tumor microenvironment that tumor infiltrated immune cell directly contact with cancer cells and EGFR down-regulation leads to reduction of PD-L1 expression on cancer cells. Further investigation is needed to elucidate the mechanism of reduction of EGFR by direct immune cell contact to cancer cells and its interaction with modulation of PD-L1 expression. This will provide novel aspects for immune therapy of breast cancer patients. Citation Format: Ayane Yamaguchi, Eiji Suzuki, Kosuke Kawaguchi, Mariko Nishie, Moe Tsuda, Masakazu Toi. Direct immune cell contact to basal-like triple negative breast cancer cells evokes downregulation of EGFR and PD-L1. [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 4149.

Liquid-based three-dimensional tumor models for cancer research and drug discovery.

Tumors are three-dimensional tissues where close contacts between cancer cells, intercellular interactions between cancer and stromal cells, adhesion of cancer cells to the extracellular matrix, and signaling of soluble factors modulate functions of cancer cells and their response to therapeutics. Three-dimensional cultures of cancer cells overcome limitations of traditionally used monolayer cultures and recreate essential characteristics of tumors such as spatial gradients of oxygen, growth factors, and metabolites and presence of necrotic, hypoxic, quiescent, and proliferative cells. As such, three-dimensional tumor models provide a valuable tool for cancer research and oncology drug discovery. Here, we describe different tumor models and primarily focus on a model known as tumor spheroid. We summarize different technologies of spheroid formation, and discuss the use of spheroids to address the influence of stromal fibroblasts and immune cells on cancer cells in tumor microenvironment, study cancer stem cells, and facilitate compound screening in the drug discovery process. We review major techniques for quantification of cellular responses to drugs and discuss challenges ahead to enable broad utility of tumor spheroids in research laboratories, integrate spheroid models into drug development and discovery pipeline, and use primary tumor cells for drug screening studies to realize personalized cancer treatment.