Mechanisms In Tumor Microenvironment Research Articles

Competing endogenous RNAs (ceRNAs) and drug resistance to cancer therapy.

Competing endogenous RNAs (ceRNAs) are transcripts that possess highly similar microRNA response elements (MREs). microRNAs (miRNAs) are short, endogenous, single-stranded non-coding RNAs (ncRNAs) that can repress gene expression by binding to MREs on the 3' untranslated regions (UTRs) of the target mRNA transcripts to suppress gene expression by promoting mRNA degradation and/or inhibiting protein translation. mRNA transcripts, circular RNAs (circRNAs), long non-coding RNAs (lncRNAs), and transcribed pseudogenes could share similar MREs, and they can compete for the same pool of miRNAs. These ceRNAs may affect the level of one another by competing for their shared miRNAs. This interplay between different RNAs constitutes a ceRNA network, which regulates many important biological processes. Cancer drug resistance is a major factor leading to treatment failure in patients receiving chemotherapy. It can be acquired through genetic, epigenetic, and various tumor microenvironment mechanisms. The involvement of ceRNA crosstalk and its disruption in chemotherapy resistance is attracting attention in the cancer research community. This review presents an updated summary of the latest research on ceRNA dysregulation causing drug resistance across different cancer types and chemotherapeutic drug classes. Interestingly, accumulating evidence suggests that ceRNAs may be used as prognostic biomarkers to predict clinical response to cancer chemotherapy. Nevertheless, detailed experimental investigations of the putative ceRNA networks generated by computational algorithms are needed to support their translation for therapeutic and prognostic applications.

Defining three ferroptosis-based molecular subtypes and developing a prognostic risk model for high-grade serous ovarian cancer.

As a newly defined regulated cell death, ferroptosis is a potential biomarker in ovarian cancer (OV). However, its underlying mechanism in tumor microenvironment (TME) and clinical prediction significance in OV remained to be elucidated. The transcriptome data of high-grade serous OV from The Cancer Genome Atlas (TCGA) database were downloaded. Molecular subtypes were classified based on ferroptosis-correlated genes from the FerrDb database by performing consensus clustering analysis. The associations between the subtypes and clinicopathologic characteristics, mutation, regulatory pathways and immune landscape were assessed. A ferroptosis-related prognostic model was constructed and verified using International Cancer Genome Consortium (ICGC) cohort and GSE70769. Three molecular subtypes of OV were defined. Patients in subtype C3 tended to have the most favorable prognosis, while subtype C1 showing more mesenchymal cells, increased immune infiltration of Macrophages_M2, lower tumor purity, and epithelial-to-mesenchymal transition (EMT) features had the poorest prognosis. A ferroptosis-related risk model was constructed using 8 genes (PDP1, FCGBP, EPHA4, GAS1, SLC7A11, BLOC1S1, SPOCK2, and CXCL9) and manifested a strong prediction performance. High-risk patients had enriched EMT pathways, more Macrophages_M2, less plasma cells and CD8 cell infiltration, greater tendency of immune escape and worse prognosis. The risk score has negatively correlated relation with LAG3, TIGIT, CTLA4, IDO1, CD27, ICOS, and IL2RB but positively correlated with PVR, CD276, and CD28. Moreover, low-risk patients were more sensitive to Cisplatin and Gefitinib, Gemcitabine. Our results could improve the understanding of ferroptosis in OV, providing promising insights for the clinical targeted therapy for the cancer.

Abstract 28: A CRISPR/Cas9 screening platform ImmuT Finder® enables in vivo T cell functional screening and identification of potent immunoregulatory targets for next-generation T cell therapy

Abstract Insufficient tumor infiltration and the presence of various immunosuppressive mechanisms in tumor microenvironment (TME) are two major challenges compromising the anti-tumor efficacy of T cell therapy post infusion. PD-1/PD-L1 blockade has been proven to benefit a portion of late-stage solid tumor patients, however KO of PD-1 may impact the long-term persistence of CAR-T cells, indicating target selection strategies for gene editing of cell therapy products may differ from antibody drugs. To discover potent and/or novel immunoregulatory targets that could maximize the function of T cell therapy, we established an in vivo CRISPR/Cas9 screening platform, ImmuT Finder®, to identify functional gene targets in primary mouse T cells. Notably, T cells carrying sgRNA library have been collected at different harvest time points post transfer based on different screening purposes; library size has been rationally designed to ensure good coverage of the whole library in harvest samples. We selected top targets from in vivo screening and quickly validated their function in primary human T cells in a 96-well array. Then, the top targets that showed significant enhancement in proliferation and function of human T cells were further selected, and their combinational effects on human peripheral T cells and TIL were tested both in vitro and in vivo. Finally, GT307 stands out as the most potent KO combination, which significantly improves serial tumor killing of TCR-T and CAR-T as well as autologous tumor cytotoxicity of TIL in vitro. Furthermore, GT307 KO TCR-T and TIL demonstrated significantly improved tumor control in mouse models than their unedited counterparts and promoted long-term persistence with low support of IL-2. In summary, these data demonstrated that our ImmuT Finder® platform enables discovery of potent and/or novel targets for the development of T cell product and supports the clinical assessment of GT307 as a next-generation T cell therapy. Citation Format: Jingwei Sun, Jiahui Jin, Jingman Wang, Yao Sheng, Fei Li, Lingyun Chen, Yongchao Tan, Zhao Xu, Yanbin Liu, Ke Liu, Yarong Liu. A CRISPR/Cas9 screening platform ImmuT Finder® enables in vivo T cell functional screening and identification of potent immunoregulatory targets for next-generation T cell therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 28.

Effects of probiotic supplementation on chronic inflammatory process modulation in colorectal carcinogenesis

The current study investigated the potential effects of probiotic supplementation on colorectal carcinogenesis chemically induced with 1,2-dimethylhydrazine (DMH) and treated with 5-fluorouracil (5FU)-based chemotherapy in mice. Animals were randomly allocated in five different groups: Control: which not receive any treatment throughout the experimental course; Colitis model group (DMH): treated with DMH; DMH+ 5FU: animals received I.P. (intraperitoneal) dose of chemotherapy on a weekly basis; DMH+PROB: animals received daily administrations (via gavage) of probiotics (Lactobacillus: acidophilus and paracasei, Bifidobacterium lactis and bifidum); and DMH+ PROB+ 5FU: animals received the same treatment as the previous groups. After ten-week treatment, mice’s large intestine was collected and subjected to colon length, histopathological, periodic acid-schiff (PAS) staining and immunohistochemistry (TLR2, MyD88, NF-κB, IL-6, TLR4, TRIF, IRF-3, IFN-γ, Ki-67, KRAS, p53, IL-10, and TGF-β) analyzes. Variance (ANOVA) and Kruskal-Wallis tests were used for statistical analysis, at significance level p 0.05. Probiotics’ supplementation has increased the production of Ki-67 cell-proliferation marker, reduced body weight, and colon shortening, as well as modulated the chronic inflammatory process in colorectal carcinogenesis by inhibiting NF-κB expression and mitigating mucin depletion. Thus, these findings lay a basis for guide future studies focused on probiotics’ action mechanisms in tumor microenvironment which might have implications in clinical practice.

Abstract 4062: The discovery and development of a CRISPR/Cas9-engineered tumor-infiltrating lymphocytes product (GT316) as a next-generation TIL therapy

Abstract Adoptive cell therapy by tumor-infiltrating lymphocytes (TILs) has demonstrated promising therapeutic effects in multiple types of solid tumors and significantly prolonged the survival of late-stage patients. However, the “prone-to-exhaustion” phenotype of the final TIL product after rapid expansion during manufacture and the presence of various immunosuppressive mechanisms in tumor microenvironment (TME) compromises the persistence and anti-tumor efficacy of TIL post infusion. To discover potential immunoregulatory targets that could maximize the function of TIL, we established a genome-wide CRISPR/Cas9 screening platform, ImmuT Finder®, to unbiasedly identify functional gene targets in primary T cells. Notably, this platform employed T cells bearing a tumor-antigen specific TCR-T that were repeatedly stimulated by tumor cells with cognate tumor antigen and demonstrated similar exhaustion profile as TIL. We selected top 30 targets after several rounds of screening and quickly validated their function in a 96-well array. Then, the top targets that showed significantly enhancement in proliferation and function of TCR-T were further selected, and their combinational effects on TIL were tested both in vitro and in vivo. Finally, double KO of GT304 and GT312 (GT316) stands out as the most potent combination, which significantly improves TIL proliferation and cytokine release, eradicates tumor growth in both CDX and PDX mouse models and promotes long-term in vivo persistence with low-dependence on IL-2. Specific and potent sgRNAs targeting both targets have been selected, and manufacturing process of GT316 TIL product has been developed (KOReTIL®). In summary, these data demonstrated that our ImmuT Finder® platform enables unbiased discovery of potent and novel targets for the development of T cell therapy and support the clinical assessment of GT316 as a next-generation TIL therapy. Currently, an investigator-initiated trial of GT316 is ongoing in China. Citation Format: Yarong Liu, Jingwei Sun, Yao Sheng, Jingman Wang, Jiahui Jin, Fei Li, Lingyun Chen, Di Zhou, Yongchao Tan, Quanwei Wang, Zhao Xu, Haibao Li, Pin Wang, Jun Cui. The discovery and development of a CRISPR/Cas9-engineered tumor-infiltrating lymphocytes product (GT316) as a next-generation TIL therapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4062.

The effect of HOXC10 gene on biological behaviors of glioma cells and mechanism in tumor microenvironment

Objective: To study the effects of Homeobox C10 (HOXC10) on biological characteristics such as migration, invasion and proliferation of glioma cancer cells and to explore the role of HOXC10 gene in glioma microenvironment. Methods: The expression level of HOXC10 in high grade glioma (glioblastoma) and low grade glioma and its effect on patient survival were analyzed by using The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) database. Hoxc10-siRNA-1, HOXC10-siRNA-2 and siRNA negative control (NC) were transfected into U251 cells according to the operation instructions of HOXC10-siRNA transfection. 100 ng/ mL recombinant protein chemokine ligand 2 (reCCL2) was added into the transfection group, and was labeled as HOXC10-siRNA-1+ reCCL2 and HOXC10-siRNA-2+ reCCL2 groups. The expressions of HOXC10 mRNA and target protein in each group was detected by real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) and western blot. The proliferation ability of cells in each group was detected by cell counting kit 8 (CCK8) method. The migration ability of cells was detected by Transwell assay and Nick assay, and cell apoptosis was detected by flow cytometry. The expression of chemokines in each group was detected by multiple factors. Co-incubation assays were performed to determine the role of HOXC10 and chemokine ligand 2 (CCL2) in recruiting and polarizing tumor-associated macrophages (M2-type macrophages). Results: The median expression level of HOXC10 in high grade gliomas was 8.51, higher than 1.00 in low grade gliomas (P<0.001) in TCGA database. The median expression level of HOXC10 in high grade gliomas was 0.83, higher than 0.00 in low grade gliomas (P=0.002) in CGGA database. The 5-year survival rate of patients with high HOXC10 expression in TCGA database was 28.2%, lower than 78.7% of those with low HOXC10 expression (P<0.001), and the 5-year survival rate of patients with high HOXC10 expression in CGGA database was 20.3%, lower than 58.0% of those with low HOXC10 expression (P<0.001). The numbers of cell migration in HOXC10-siRNA-1 group and HOXC10-siRNA-2 group were (45±3) and (69±4) respectively, lower than (159±3) in NC group (P<0.05). The cell mobility of HOXC10-siRNA-1 group and HOXC10-siRNA-2 group at 48 hours were (15±2)% and (28±4)% respectively, lower than (80±5)% of NC group (P<0.05). The expressions of vimentin in HOXC10-siRNA-1 group and HOXC10-siRNA-2 group were (141 740.00±34 024.56) and (94 655.00±5 687.97), N-cadherin were (76 810.00±14.14) and (94 254.00±701.45), β-catenin were (75 786.50±789.84) and (107 296.50±9 614.53), lower than (233 768.50±34 114.37), (237 154.50±24 715.50) and (192 449.50±24 178.10) of NC group (P<0.05). The A value of HOXC10-siRNA-1 group and HOXC10-siRNA-2 group were (0.44±0.05) and (0.32±0.02) at 96 hours, lower than 0.92±0.12 of NC group (P<0.05). The apoptosis rates of HOXC10-siRNA-1 group and HOXC10 siRNA-2 group were (10.23±1.24)% and (13.81±2.16)%, higher than (4.60±0.07)% of NC group (P<0.05). The expression levels of CCL2 in U251 cells in HOXC10-siRNA-1 and HOXC10-siRNA-2 groups were (271.63±44.27) and (371.66±50.21), lower than (933.93±29.84) in NC group (P<0.05). The expression levels of CCL5 (234.81±5.95 and 232.62±5.72), CXCL10 (544.13±48.14 and 500.87±15.65) and CXCL11 (215.75±15.30 and 176.18±16.49) in HOXC10-siRNA-1 and HOXC10-siRNA-2 groups were higher than those in NC group (9.98±0.71, 470.54±18.84 and 13.55±0.73, respectively, P<0.05). The recruited numbers of CD14(+) THP1 in HOXC10-siRNA-1 and HOXC10-siRNA-2 groups were (159.33±1.15) and (170.67±1.15), respectively, lower than (360.00±7.81) in NC group (P<0.05), while addition of reCCL2 promoted the recruitment of CD14(+) THP1 cells (287.00±3.61 and 280.67±2.31 in HOXC10-siRNA-1+ reCCL2 group and HOXC10-siRNA-2+ reCCL2 group, respectively, P<0.05). The expressions level of M2-type macrophage-related gene TGF-β in HOXC10-siRNA-1 group and HOXC10-siRNA-2 group were (0.30±0.02) and (0.28±0.02), respectively, lower than (1.06±0.10) in NC group (P<0.05). The expressions level of M1-related gene NOS2 in HOXC10-siRNA-1 and HOXC10-siRNA-2 were (11 413.95±1 911.85) and (5 894.00±945.21), respectively, higher than (13.39±4.32) in NC group (P<0.05). Conclusions: The expression of HOXC10 in glioma is high and positively correlated with the poor prognosis of glioma patients. Knockdown of HOXC10 can inhibit the proliferation, migration and metastasis of human glioma U251 cells. HOXC10 may play an immunosuppressive role in glioma microenvironment by promoting the expression of CCL2 and recruiting and polarizing tumor-associated macrophages (M2 macrophages).

Tumor microenvironment mechanisms and bone metastatic disease progression of prostate cancer

During disease progression from primary towards metastatic prostate cancer (PCa), and in particular bone metastases, the tumor microenvironment (TME) evolves in parallel with the cancer clones, altering extracellular matrix composition (ECM), vasculature architecture, and recruiting specialized tumor-supporting cells that favor tumor spread and colonization at distant sites. We introduce the clinical profile of advanced metastatic PCa in terms of common genetic alterations. Findings from recently developed models of PCa metastatic spread are discussed, focusing mainly on the role of the TME (mainly matrix and fibroblast cell types), at distinct stages: premetastatic niche orchestrated by the primary tumor towards the metastatic site and bone metastasis. We report evidence of premetastatic niche formation, such as the mechanisms of distant site conditioning by extracellular vesicles, chemokines and other tumor-derived mechanisms, including altered cancer cell-ECM interactions. Furthermore, evidence supporting the similarities of stroma alterations among the primary PCa and bone metastasis, and contribution of TME to androgen deprivation therapy resistance are also discussed. We summarize the available bone metastasis transgenic mouse models of PCa from a perspective of pro-metastatic TME alterations during disease progression and give an update on the current diagnostic and therapeutic radiological strategies for bone metastasis clinical management.

Macrophage differentiation and molecular mechanism intumor microenvironment

Macrophage differentiation and molecular mechanism intumor microenvironment

Therapeutic Targets in Diffuse Midline Gliomas-An Emerging Landscape.

Simple SummaryDiffuse midline gliomas (DMGs) remain one of the most devastating childhood brain tumour types, for which there is currently no known cure. In this review we provide a summary of the existing knowledge of the molecular mechanisms underlying the pathogenesis of this disease, highlighting current analyses and novel treatment propositions. Together, the accumulation of these data will aid in the understanding and development of more effective therapeutic options for the treatment of DMGs.Diffuse midline gliomas (DMGs) are invariably fatal pediatric brain tumours that are inherently resistant to conventional therapy. In recent years our understanding of the underlying molecular mechanisms of DMG tumorigenicity has resulted in the identification of novel targets and the development of a range of potential therapies, with multiple agents now being progressed to clinical translation to test their therapeutic efficacy. Here, we provide an overview of the current therapies aimed at epigenetic and mutational drivers, cellular pathway aberrations and tumor microenvironment mechanisms in DMGs in order to aid therapy development and facilitate a holistic approach to patient treatment.

Abstract LBA022: IMM20324, a first-in-class, anti-interleukin-38 monoclonal antibody, rescues myeloid cell activation in vitro and induces robust anti-tumor responses in vivo

Abstract Immune checkpoint inhibitors that overcome T cell suppressive mechanisms in tumors have revolutionized the treatment of cancer. However, therapies targeting innate immune cell subsets that orchestrate adaptive immune responses could significantly improve the incidence of clinical response by more effectively activating a multi-lineage response to the tumor. Here, we show that IMM20324, an antibody that binds and neutralizes IL-38, enhances innate immune cell function in vitro and inhibits tumor growth in vivo. IMM20324 binds human, mouse and cynomolgus IL-38 and inhibits the binding of IL-38 to its putative receptors, IL1RAPL1 and IL-36R. In vivo, IMM20324 administration leads to inhibition of tumor growth and improved survival in two different syngeneic tumor models. Importantly, while IMM20324 targets innate immune cells, antibody treatment leads to the induction of immunological memory responses that induce tumor rejection following tumor rechallenge. Together, our data support the hypothesis that IL-38 plays an important role in tumor immunity and that therapies targeting IL-38 could reverse suppressive mechanisms in tumor microenvironment. IMM20324 demonstrated favorable in vitro potency and in vivo efficacy and therefore represents a promising development candidate with the potential to treat multiple cancers. Citation Format: John P Dowling, Pavel A Nikitin, Fang Shen, James P Finn, Nirja Patel, Cezary Swider, Jamie Steele, Halley Shukla, Matthew K Robinson, Karen Lundgren, Benjamin C Harman. IMM20324, a first-in-class, anti-interleukin-38 monoclonal antibody, rescues myeloid cell activation in vitro and induces robust anti-tumor responses in vivo [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr LBA022.

Screening and Identification of Prognostic Tumor-Infiltrating Immune Cells and Genes of Endometrioid Endometrial Adenocarcinoma: Based on The Cancer Genome Atlas Database and Bioinformatics.

BackgroundEndometrioid endometrial adenocarcinoma (EEA) is one of the most common tumors in the female reproductive system. With the further understanding of immune regulation mechanism in tumor microenvironment, immunotherapy is emerging in tumor treatment. However, there are few systematic studies on EEA immune infiltration.MethodsIn this study, prognostic tumor-infiltrating immune cells (TIICs) and related genes of EEA were comprehensively analyzed for the first time through the bioinformatics method with CIBERSORT algorithm as the core. Gene expression profile data were downloaded from the TCGA database, and the abundance ratio of TIICs was obtained. Kaplan–Meier analysis and Cox regression analysis were used to identify prognostic TIICs. EEA samples were grouped according to the risk score in Cox regression model. Differential analysis and functional enrichment analyses were performed on high- and low-risk groups to find survival-related hub genes, which were verified by Tumor Immune Estimation Resource (TIMER).ResultFour TIICs including memory CD4+ T cells, regulatory T cells, natural killer cells and dendritic cells were identified. And two hub gene modules were found, in which six hub genes including APOL1, CCL17, RBP4, KRT15, KRT71, and KRT79 were significantly related to overall survival and were closely correlated with some certain TIICs in the validation of TIMER.ConclusionIn this study, four prognostic TIICs and six hub genes were found to be closely related to EEA. These findings provided new potential targets for EEA immunotherapy.

Clinicopathological analysis of immunohistochemical expression of CD47 and SIRPα in adult T-cell leukemia/lymphoma.

The interaction of CD47 and signal-regulatory protein alpha (SIRPα) induces "don't eat me signal", leading suppression of phagocytosis. This signal can affect the clinical course of malignant disease. Although CD47 and SIRPα expression are associated with clinicopathological features in several neoplasms, the investigation for adult T-cell leukemia/lymphoma (ATLL) has not been well-documented. This study aimed to declare the association between CD47 and SIRPα expression and clinicopathological features in ATLL. We performed immunostaining on 73 biopsy samples and found that CD47 is primarily expressed in tumor cells, while SIRPα is expressed in non-neoplastic stromal cells. CD47 positive cases showed significantly higher FoxP3 (P = .0232) and lower CCR4 (P = .0214). SIRPα positive cases presented significantly better overall survival than SIRPα negative cases (P = .0132). SIRPα positive cases showed significantly HLA class I (P = .0062), HLA class II (P = .0133), microenvironment PD-L1 (miPD-L1) (P = .0032), and FoxP3 (P = .0229) positivity. In univariate analysis, SIRPα expression was significantly related to prognosis (Hazard ratio [HR] 0.470; 95% confidence interval [CI] 0.253-0.870; P = .0167], although multivariate analysis did not show SIPRα as an independent prognostic factor. The expression of SIRPα on stromal cells reflects activated immune surveillance mechanism in tumor microenvironment and induce good prognosis in ATLL. More detailed studies for gene expression or genomic abnormalities will disclose clinical and biological significance of the CD47 and SIRPα in ATLL.

Tumor-associated tissue eosinophilia predicts favorable clinical outcome in solid tumors: a meta-analysis

BackgroundActivated eosinophils have been deemed to affect carcinogenesis and tumor progression via various mechanisms in tumor microenvironment. However, the prognostic role of tumor-associated tissue eosinophilia (TATE) in human cancers remains controversial. Therefore, we conducted this meta-analysis to better comprehend the association between TATE and clinical outcomes of patients.MethodsWe searched PubMed, Embase and EBSCO to determine the researches assessing the association between TATE and overall survival (OS) and/or disease-free survival (DFS) in patients with cancer, then combined relevant data into hazard ratios (HRs) or odds ratio (OR) for OS, DFS and clinicopathological features including lymph node metastasis etc. with STATA 12.0.ResultsTwenty six researches with 6384 patients were included in this meta-analysis. We found that the presence of TATE was significantly associated with improved OS, but not with DFS in all types of cancers. In stratified analyses based on cancer types, pooled results manifested that the infiltration of eosinophils was remarkably associated with better OS in esophageal carcinoma and colorectal cancer. In addition, TATE significantly inversely correlated with lymph node metastasis, tumor stage and lymphatic invasion of cancer.ConclusionTATE promotes survival in cancer patients, suggesting that it is a valuable prognostic biomarker and clinical application of biological response modifiers or agonists promoting TATE may be the novel therapeutic strategy for patients.

Breast Tumor Microenvironment: Emerging target of therapeutic phytochemicals

Triple negative breast cancer (TNBC) is the most aggressive and challenging form of breast cancers. Tumor microenvironment (TME) of TNBC is associated with induction of metastasis, immune system suppression, escaping immune detection and drug resistance. TME is highly complex and heterogeneous, consists of tumor cells, stromal cells and immune cells. The rapid expansion of tumors induce hypoxia, which concerns the reprogramming of TME components. The reciprocal communication of tumor cells and TME cells predisposes cancer cells to metastasis by modulation of developmental pathways, Wnt, notch, hedgehog and their related mechanisms in TME. Dietary phytochemicals are non-toxic and associated with various human health benefits and remarkable spectrum of biological activities. The phytochemicals serve as vital resources for drug discovery and also as a source for breast cancer therapy. The novel properties of dietary phytochemicals propose platform for modulation of tumor signaling, overcoming drug resistance, and targeting TME. Therefore, TME could serve as promising target for the treatment of TNBC. This review presents current status and implications of experimentally evaluated therapeutic phytochemicals as potential targeting agents of TME, potential nanosystems for targeted delivery of phytochemicals and their current challenges and future implications in TNBC treatment. The dietary phytochemicals especially curcumin with significant delivery system could prevent TNBC development as it is considered safe and well tolerated in phase II clinical trials.

Abstract 713: Upregulation of immune checkpoint molecules on Treg cells in tumor microenvironment reinforces immune exhaustion in cancer patients

Abstract Purpose: Regulatory T (Treg) cells perform the immune suppressive function in cancer, but their suppressive mechanism in tumor microenvironment (TME) has not been clearly elucidated. We aim to identify the phenotype and functional mechanism of Treg cells in TME from cancer patients. Experimental Design: We collected 72 malignant effusion (ME) and peripheral blood (PB) specimens from stage IV cancer patients and 10 tumor tissue (TM) and PB from lung cancer patients who underwent surgery. Lymphocytes from ME, TM, and PB were analyzed for subtype of Tconv and Treg cells, and their expressions of immune checkpoint (IC) molecules including programmed death (PD-1), cytotoxic T lymphocyte antigen-4 (CTLA-4), and T cell immunoglobulin containing molecule-3 (TIM-3) using by flow cytometry. To examine the functional role of PD-1 expressed Treg cells, TC-1 lung cancer mouse model was used. Result: Upregulation of PD-1 on Treg cells in TM and ME compared to PB was even more distinguishable than that on CD4+ and CD8+ Tconv cells. To clarify the characteristics of tumor infiltrating Treg cells, we comprehensively examined the characteristics of Treg cells from tumor, peri-tumor, and PB in lung cancer patients by analyzing the expression of IC molecules including PD-1, TIM-3, CTLA-4, and TIGIT, of which PD-1 is the highest expressed on tumor infiltrating Treg cells. To investigate the mechanism by which Treg cells mediate immune suppression, we compared the suppressive activity of Treg cells expressing high and low levels of PD-1 by co-culturing each population with naïve CD8+ T cells with or without αCD3/CD28 stimulation. This was more potently inhibited in co-cultures with PD-1high tumor infiltrating Treg cells than in those with PD-1low Treg cells. PD-1 blocked tumor infiltrating Treg cells demonstrated a significantly decreased suppressive function in the proliferation of CD8+ cells and their IFN-γ production. These results implicate that PD-1 expressed tumor infiltrating Treg confers the suppressive function of proliferation in CD8+ T cells through PD-1: PD-L1 interaction. Conclusion: Our study evidently demonstrated that upregulated PD-1 on tumor infiltrating Treg cells and their PD-1: PD-L1 interaction could be potential cause of T cell suppression, which might be helpful to completely understand their suppressive mechanism in cancer patients. Citation Format: Hye Ryun Kim, Hyo Jin Park, Jimin Son, Hyo Sup Shim, Byoung Chul Cho, Sun Young Rha, Sang-Jun Ha. Upregulation of immune checkpoint molecules on Treg cells in tumor microenvironment reinforces immune exhaustion in cancer patients [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 713.

A Spatio-Temporal Model of Macrophage-Mediated Drug Resistance in Glioma Immunotherapy.

The emergence of drug resistance is often an inevitable obstacle that limits the long-term effectiveness of clinical cancer chemotherapeutics. Although various forms of cancer cell-intrinsic mechanisms of drug resistance have been experimentally revealed, the role and the underlying mechanism of tumor microenvironment in driving the development of acquired drug resistance remain elusive, which significantly impedes effective clinical cancer treatment. Recent experimental studies have revealed a macrophage-mediated drug resistance mechanism in which the tumor microenvironment undergoes adaptation in response to macrophage-targeted colony-stimulating factor-1 receptor (CSF1R) inhibition therapy in gliomas. In this study, we developed a spatio-temporal model to quantitatively describe the interplay between glioma cells and CSF1R inhibitor-targeted macrophages through CSF1 and IGF1 pathways. Our model was used to investigate the evolutionary kinetics of the tumor regrowth and the associated dynamic adaptation of the tumor microenvironment in response to the CSF1R inhibitor treatment. The simulation result obtained using this model was in agreement with the experimental data. The sensitivity analysis revealed the key parameters involved in the model, and their potential impacts on the model behavior were examined. Moreover, we demonstrated that the drug resistance is dose-dependent. In addition, we quantitatively evaluated the effects of combined CSFR inhibition and IGF1 receptor (IGF1R) inhibition with the goal of designing more effective therapies for gliomas. Our study provides quantitative and mechanistic insights into the microenvironmental adaptation mechanisms that operate during macrophage-targeted immunotherapy and has implications for drug dose optimization and the design of more effective combination therapies. Mol Cancer Ther; 17(4); 814-24. ©2018 AACR.

Regulatory mechanisms of tumor microenvironment and progression of ovarian cancer peritoneal dissemination, which is induced by intraperitoneal transformation of tumor cells

Regulatory mechanisms of tumor microenvironment and progression of ovarian cancer peritoneal dissemination, which is induced by intraperitoneal transformation of tumor cells

Mitochondrial deficiency impairs hypoxic induction of HIF-1 transcriptional activity and retards tumor growth.

Mitochondria can be involved in regulating cellular stress response to hypoxia and tumor growth, but little is known about that mechanistic relationship. Here, we show that mitochondrial deficiency severely retards tumor xenograft growth with impairing hypoxic induction of HIF-1 transcriptional activity. Using mtDNA-deficient ρ0 cells, we found that HIF-1 pathway activation was comparable in slow-growing ρ0 xenografts and rapid-growing parental xenografts. Interestingly, we found that ex vivo ρ0 cells derived from ρ0 xenografts exhibited slightly increased HIF-1α expression and modest HIF-1 pathway activation regardless of oxygen concentration. Surprisingly, ρ0 cells, as well as parental cells treated with oxidative phosphorylation inhibitors, were unable to boost HIF-1 transcriptional activity during hypoxia, although HIF-1α protein levels were ordinarily increased in these cells under hypoxic conditions. These findings indicate that mitochondrial deficiency causes loss of hypoxia-induced HIF-1 transcriptional activity and thereby might lead to a constitutive HIF-1 pathway activation as a cellular adaptation mechanism in tumor microenvironment.

Abstract 1119: Utilization of the TGFβ signaling pathway and cell substrate interaction in a novel anti-cancer drug screen

Abstract The TGF-β signaling pathway has been demonstrated to play a multifunctional and complicated role in cancer progression, making it an intriguing target for anti-cancer therapeutics. TGF-β signaling drives proliferation of cancer cells, invasion at the tumor periphery, and is associated with metastatic potential in a number of cancer types. Tumors expressing TGF-β activity are positively correlated with poorer prognosis in patients. Complicating the role of TGF-β signaling in cancer progression is that TGF-β signaling leads to distinct cellular responses at different stages of cancer progression. How the same signal transduction pathway drives distinct cellular responses is a critical question. One likely possibility is that TGF-β signaling is highly context dependent. Changes in the tumor microenvironment, as occur during cancer progression, alter the outcome of TGF-β signaling. As an extreme example of how TGF-β signaling is affected by micro-environmental stimuli, we and others previously reported that certain non-cancerous cells on rigid collagen I substrates become sensitized to HGF-induced epithelial scattering in response to TGF-β, while cells on pliant collagen I substrates undergo apoptosis in response to TGF-β. Given that tumors are typically rigid tissues, we sought to define whether cancer cells would respond to TGF-β by undergoing apoptosis when cultured on pliant substrates. We plated a wide variety of cancer cell lines on highly pliant substrates, treated then with TGF-β, and observed cell viability over time. While a number of cells showed no apoptotic response to TGF-β signaling under any condition, we find that a significant number of cancer cells derived from solid tumors respond to TGF-β signaling on pliant substrates by undergoing apoptosis. Another group of cell lines undergo apoptosis on pliant substrates in the absence of any TGF-β stimulation. Reasoning that perturbation of cellular signaling that communicated substrate rigidity to cells might sensitize them to apoptosis in response to TGF-β, we designed a high-content high throughput screen to look for molecules that would induce cells to undergo apoptosis in response to TGF-β signaling. This chemical genetics approach will yield cues into the mechanism of tumor microenvironment sensing, as well as provide lead compounds for development of novel therapeutics Note: This abstract was not presented at the meeting. Citation Format: Wontak Kim, Jacob P. Hoj, Nicholas E. Saguibo, Kendra E. Fullmer. Utilization of the TGFβ signaling pathway and cell substrate interaction in a novel anti-cancer drug screen. [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 1119. doi:10.1158/1538-7445.AM2014-1119

Tumor dormancy: potential therapeutic target in tumor recurrence and metastasis prevention

In past decades, cancer patient survival has been improved with earlier detection and advancements in therapy. However, many patients who exhibit no clinical symptoms after frontline therapy subsequently suffer, often many years later, aggressive tumor recurrence. Cancer recurrence represents a critical clinical challenge in effectively treating malignancies and for patients’ quality of life. Tumor cell dormancy may help to explain treatment resistance and recurrence or metastatic reactivation. Understanding the dormant stage of tumor cells may help in discovering ways to maintain the dormant state or permanently eliminate dormant residual disseminated tumor cells. Over the past decade, numerous studies indicate that various mechanisms of tumor dormancy exist, including cellular dormancy (quiescence), angiogenic dormancy, and immunologic dormancy. In this short review, we summarize recent experimental and clinical evidence for these three mechanisms and other possible tumor microenvironment mechanisms that may influence tumor dormancy.