Course Of Tumor Growth Research Articles

Spatial distribution of tumor-associated macrophages in an orthotopic prostate cancer mouse model.

Mounting evidence suggests that the immune landscape within prostate tumors influences progression, metastasis, treatment response, and patient outcomes. In this study, we investigated the spatial density of innate immune cell populations within NOD.SCID orthotopic prostate cancer xenografts following microinjection of human DU145 prostate cancer cells. Our laboratory has previously developed nanoscale liposomes that attach to leukocytes via conjugated E-selectin (ES) and kill cancer cells via TNF-related apoptosis inducing ligand (TRAIL). Immunohistochemistry (IHC) staining was performed on tumor samples to identify and quantify leukocyte infiltration for different periods of tumor growth and E-selectin/TRAIL (EST) liposome treatments. We examined the spatial-temporal dynamics of three different immune cell types infiltrating tumors using QuPath image analysis software. IHC staining revealed that F4/80+ tumor-associated macrophages (TAMs) were the most abundant immune cells in all groups, irrespective of time or treatment. The density of TAMs decreased over the course of tumor growth and decreased in response to EST liposome treatments. Intratumoral versus marginal analysis showed a greater presence of TAMs in the marginal regions at 3 weeks of tumor growth which became more evenly distributed over time and in tumors treated with EST liposomes. TUNEL staining indicated that EST liposomes significantly increased cell apoptosis in treated tumors. Additionally, confocal microscopy identified liposome-coated TAMs in both the core and periphery of tumors, highlighting the ability of liposomes to infiltrate tumors by "piggybacking" on macrophages. The results of this study indicate that TAMs represent the majority of innate immune cells within NOD.SCID orthotopic prostate tumors, and spatial density varies widely as a function of tumor size, duration of tumor growth, and treatment of EST liposomes.

Correlation between genotype and phenotype with special attention to hearing in 14 Japanese cases of NF2-related schwannomatosis

NF2-related schwannomatosis (NF2) is an autosomal dominant genetic disorder caused by variants in the NF2 gene. Approximately 50% of NF2 patients inherit pathogenic variants, and the remainder acquire de novo variants. NF2 is characterized by development of bilateral vestibular schwannomas. The genetic background of Japanese NF2 cases has not been fully investigated, and the present report performed a genetic analysis of 14 Japanese NF2 cases and examined genotype–phenotype correlations. DNA samples collected from peripheral blood were analyzed by next-generation sequencing, multiplex ligation-dependent probe amplification analysis, and in vitro electrophoresis. Ten cases had pathogenic or likely pathogenic variants in the NF2 gene, with seven truncating variants and three non-truncating variants. The age of onset in all seven cases with truncating variants was < 20 years. The age of onset significantly differed among cases with truncating NF2 variants, non-truncating NF2 variants, and no NF2 variants. However, the clinical course of tumor growth and hearing deterioration were not predicted only by germline pathogenic NF2 variants. The rate of truncating variants was higher in the present study than that of previous reports. Genotype–phenotype correlations in the age of onset were present in the analyzed Japanese NF2 cases.

The Role of Hypoxia in Endometrial Cancer.

Endometrial cancer represents the most frequent neoplasia from the corpus uteri and comprises the 14th leading cause of death in women worldwide. Risk factors that contribute to the disease include early menarche, late menopause, nulliparity, and menopausal hormone use, as well as hypertension and obesity comorbidities. The clinical effectiveness of chemotherapy is variable, suggesting that novel molecular targeted therapies against specific cellular processes associated with the maintenance of cancer cell survival and therapy resistance ameliorate the rates of success in endometrial cancer treatment. In the course of tumor growth, cancer cells must adapt to decreased oxygen availability in the microenvironment by upregulation of hypoxia-inducible factors, which orchestrate the activation of a transcriptional program leading to cell survival. During this adaptative process, the hypoxic cancer cells may acquire invasive and metastatic properties as well as increased cell proliferation and resistance to chemotherapy, enhanced angiogenesis, vasculogenic mimicry, and maintenance of cancer cell stemness, which contribute to more aggressive cancer phenotypes. Several studies have shown that hypoxia-inducible factor 1 alpha (HIF-1α) protein is aberrantly overexpressed in many solid tumors of the breast, prostate, ovarian, bladder, colon, brain, and pancreas. Thus, it has been considered an important therapeutic target. Here, we reviewed the current knowledge of the relevant roles of cellular hypoxia mechanisms and HIF-1α functions in diverse processes associated with endometrial cancer progression. In addition, we also summarize the role of microRNAs in the posttranscriptional regulation of protein-encoding genes involved in the hypoxia response in endometrial cancer. Finally, we pointed out the need for urgent targeted therapies to impair the cellular processes activated by hypoxia in the tumor microenvironment.

Predicting the effectiveness of chemotherapy using stochastic ODE models of tumor growth

Ordinary differential equation (ODE) models of cancer growth are often used to predict tumor growth and form the basis for more complex models used in personalized medicine. Unfortunately, ODE models provide predictions of the average behavior of the cell population neglecting the fact that cells are discrete objects subject to discrete events. This kind of stochasticity can dramatically change the time course of tumor growth, particularly when the cell population is small. Here, we investigate stochastic versions of seven common ODE models of cancer growth to determine the role of stochasticity in eradicating tumors via chemotherapy. We find that stochasticity leads to differences in predictions among the different models of both the level of chemotherapy needed to cure a tumor and the time it takes to achieve a cure. Our results highlight the need for more investigation of which model provides the best description of cancer growth.

Continuous formation of small clusters with LGR5-positive cells contributes to tumor growth in a colorectal cancer xenograft model

AbstractNew cancer characteristics can be discovered by focusing on the process of tumor formation. Cancer stem cells (CSCs) are a key subpopulation, as they are theorized to be at the apex of the tumor hierarchy. We can better understand their function in the tumor hierarchy by using sectioned samples to observe the growth of tumors from their origins as CSCs. In this study, we evaluated the growth of moderate differentiated colorectal cancer from LGR5-positive cells, which is a CSC marker of colorectal cancer, using xenograft and three-dimensional culture models spatiotemporally. These cells express LGR5 at high levels and show CSC phenotypes. To detect them, we used a previously generated antibody that specifically targets LGR5, and were therefore able to observe LGR5-positive cells aggregating into small clusters (sCLs) over the course of tumor growth. Because these LGR5-expressing sCLs formed continuously during growth mainly in the invasive front, we concluded that the structure must contribute significantly to the expansion of CSCs and to tumor growth overall. We confirmed the formation of sCLs from gland structures using a three-dimensional culture model. In addition, sCLs exhibited upregulated genes related to stress response and partial/hybrid epithelial–mesenchymal transition (EMT), as well as genes reported to be prognosis factors. Finally, sCLs with high LGR5 expression were identified in clinical samples. Based on these results, we elucidate how sCLs are an important contributors to tumor growth and the expansion of CSCs.This study demonstrates that small clusters (sCLs) of tumor cells with high expression of LGR5 continuously form in the invasive front in a colorectal cancer xenograft model. This structure is characterized by stress response and partial/hybrid epithelial-mesenchymal transition. These sCLs are an important contributor to tumor growth and the expansion of cancer stem cells.

Abstract 2749: Age-related cancer drug toxicity and efficacy, and immune modulation in C57BL6J syngeneic model

Abstract Cancer has a higher incidence in the elderly and immunotherapy is widely applied to this population. However, the majority of preclinical studies assessing drug toxicity and efficacy have been done in young healthy mice, which could lead to translational failure. The goals of this study were to establish tumor models in aged mice for a better representation of cancer patients, and to examine the effects of aging on tumor growth, toxicity and efficacy of cancer treatment, and immune cell populations in syngeneic models using C57BL/6J mice of different ages. Young (7 weeks), mid-aged (56-58 weeks) and aged (76-78 weeks) C57BL/6J female mice were used for this study. To evaluate the maximum tolerated dose, young and aged mice were dosed with the standard of care cancer drugs (docetaxel, cisplatin, and doxorubicin) and body weight was monitored three times a week until mice reached endpoint criteria. Syngeneic tumor models were established using three different mouse cancer cell lines, B16-F10 melanoma, MC38 colon adenocarcinoma, and E0771 breast cancer. Several different concentrations of cells were injected subcutaneously and tumor growth kinetics were evaluated three times weekly. For efficacy study, mice were randomly assigned to isotype control or Anti-PD1 (8 mg/kg) treatment groups, and were dosed intravenously twice weekly for 3 weeks. One week after the last dose, whole blood and tumor samples were collected for flow cytometry analysis for immune cell profiling on B cells, T cells, NK cells. Aged mice showed higher toxicity against docetaxel, cisplatin, and doxorubicin compared to their young counterparts. Age-related tumor growth kinetics varied based on tumor models. Aging did not affect tumor growth kinetics of B16-F10 tumors, while aged mice showed slowed growth of MC38 tumors and faster growth of E0771 tumors. Across all tumor models, aged mice lost body weight while young mice gained body weight over the course of tumor growth, suggesting potential cancer-related cachexia in aged mice. Comparisons of PD-1 response in the various age groups with different tumors showed that anti-PD1 treatment significantly slowed down tumor growth in mid-aged (58 weeks) mice with B16-F10 tumors, but not in young or aged mice. However, the same treatment showed significant suppression of tumor growth in all age groups with the MC38 tumors. This effect might be partly caused by changes in the immune cell infiltration profile with aging. In conclusion, we have established syngeneic tumor models using aged mice and found aged mice exhibit higher toxicity against drugs while the effect of aging on tumor growth kinetics varies depending on models. Differences in immune cell infiltration in the tumor might be an underlying event that causes age-related differences in response to anti-PD1 treatment. The integration of aging in cancer research could potentially bridge the gap between preclinical studies and clinical outcomes. Citation Format: Jiwon Yang, Andrew Schile, Mingshan Cheng, James Keck. Age-related cancer drug toxicity and efficacy, and immune modulation in C57BL6J syngeneic model [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 2749.

88P - Transcription factors of snail family in the regulation of resistance of breast cancer cells to hypoxic conditions

BackgroundIn the course of tumor growth, the cells that are far from the blood vessel are exposed to hypoxic conditions. As part of this process transcription factors (TFs) of the Snail family (Snail, Slug, Twist1, and Zeb1) are activated launching the epithelial-mesenchymal transition (EMT) program. Snail family factors are the most studied as stimulators of EMT, promoting tumor progression, migration and invasion of tumor cells. The aim of our research is to study adaptive mechanisms of human breast cancer (BC) cells to hypoxia and the analysis of the role of the TF Snail in this process. MethodsWe used human BC cells MCF-7, MDA-MB-231 and HBL-100 which were cultured in standard DMEM containing 10% fetal calf serum at 37oC and 5% СО2. For hypoxia modeling, the cells were cultured in a CO2-incubator maintaining O2 concentration at 1%. ResultsKnockdown of the Snail by small interfering RNA (siRNA) leads to increased sensitivity of breast cancer cells to hypoxia, due to increased blocking of cells in the S-phase of cell cycle. Cells were more resistant to hypoxia at a lower density, where Snail expression was increased, but further hyperexpression of Snail had not lead to increased resistance to hypoxia. Knockdown of Snail leads to an compensatory increase of Slug`s expression, while the knockdown of Twist1 and Zeb1 leads to decreased Slug expression. Knockdown of Twist1 decreases cell proliferation both in hypoxia and normoxia, through activation of cell cycle inhibitor p21WAF1, specifically in the G2/M phase, in p53-wild type HBL-100 cells. We used a chemical inhibitor of p53-Snail interaction GN25, to examine if blocking of this interaction could lead to increased sensitivity in hypoxia. We have shown that this compound has a greater cytotoxic effect in normoxia than hypoxia, due to increased Snail activity. ConclusionsModulation of Snail-associated signaling pathways is a perspective target for increase of cancer cell tolerance to chronic hypoxia, and inhibition of metastatic process in breast cancer cells. Legal entity responsible for the studyThe authors. FundingGrant no. 14.W03.31.0020 between the Ministry of Science and Education of the Russian Federation and Institute of Gene Biology, Russian Academy of Sciences. DisclosureAll authors have declared no conflicts of interest.

Bone Morphogenic Protein Receptor 1α and its ligands as a signaling circuit modulating immune response

Abstract Despite increased understanding of how the transforming growth factor-β (TGF-β) regulates T cell functions, the immunomodulatory roles of other members of the TGF-β cytokine family, especially bone morphogenetic proteins, remain largely unknown. We have found that Bone Morphogenic Protein Receptor 1α (BMPR1α, Alk-3) expressed by activated effector and regulatory CD4+ T cells, modulates functions of both of these cell types by promoting generation of adaptive TR and inhibiting generation of Th17 cells from naive CD4+ T cells. Mice where BMPR1α is deleted in T cells (BMPR1αT− mice) had a decreased proportion of thymic derived TR cells. Activation of BMPR1α deficient (BMPR1α−) CD4+ T cells leads to generation of Th1/Th17-like effector cells expressing high levels of inflammatory cytokines, including IFN-γ, IL-17 and TNF family proteins. Effector CD4+ T cells activated by dendritic cells expressing BMP inhibitors expressed lower levels of PD1. Immunization of BMPR1αT− mice induced vigorous inflammatory response and mice were able to better control B16 melanoma tumors. Tumor infiltrate had very few TR cells and higher proportion of CD8+ T cells compared to tumors in wild type mice. These data demonstrate that TGF-β mediated immunosuppression in the course of tumor growth can be bypassed by inhibition of BMPR1α signaling. Transcriptome analysis of wild type and BMPR1α− CD4+ Th cells revealed differential expression of transcription factors, cytokines and cytokine receptors and signaling molecules essential to establish regulatory networks supporting Th17 or TR cells. This suggests that BMPR1α is a potential target to augment effector Th cell responses.

Research progress in relationship between microbes and tumor immunity

Microbes are closely associated with tumor development. The interactions between microbes and immune system contribute to tumor progression and metastasis. This review focused on the interactions between microbes and immune cells (macrophages, T cells, myeloid-derived suppressor cells and other immune cells) in the course of tumor growth, and summarized the roles of microbes in tumor immunotherapies, aiming to improve the overall understanding of the mechanisms for microbes affecting tumors, and provide ideas for tumor prevention and future immunotherapies. Key words: Microbes; Tumor; Immune cells; Immunotherapy

When did the glioblastoma start growing, and how much time can be gained from surgical resection? A model based on the pattern of glioblastoma growth in vivo

ObjectivesObservational data on the natural course of tumor growth in humans is sparse, and mathematical models of tumor growth are often needed to answer questions related to growth. In this study, a theoretical model of glioblastoma growth was used to investigate two questions often asked by patients and clinicians. First, when did the tumor start growing? Second, how much survival time can be gained from various extents of surgical resection (EOR)?. Patients and methodsA gompertzian growth curve was fitted from observational data of pre-treatment growth from 106 glioblastoma patients based on repeated volume segmentations. The curve was used to find the theoretical time since tumor initiation. In addition, as a proxy for the potential survival gain from surgery, the number of days until re-growth would reach the preoperative tumor volume were calculated for different extents of resection. ResultsThe estimated age of the glioblastomas at diagnosis was median 330 days, but ranging from 156 days to 776 days, depending on the tumor volume at diagnosis. The median survival gains from 50%, 75%, 90%, 95% and 99% EOR were, 1.4, 2.5, 3.6, 4.3, and 5.6 months, respectively. However, survival benefit from surgery also depends on lesion volume. In theory, 100 days may be gained from 95% EOR in a 10 mL lesion or a 50% EOR in a 90 ml lesion. ConclusionIn conclusion, we postulate that glioblastoma might originate median 330 days before the diagnosis, assuming the same growth pattern and biology from day one. The theoretical survival benefit of glioblastoma resection is much higher with higher EORs, suggesting that the last milliliters of resection matter the most. Our data also suggest that gain from resection is higher in larger lesions, suggesting that lesion volume may be taken into account in clinical decision-making.

L-leucine dietary supplementation modulates muscle protein degradation and increases pro-inflammatory cytokines in tumour-bearing rats

Cancer cachexia is characterised by involuntary weight loss associated with systemic inflammation and metabolic changes. Studies aimed at maintaining lean body mass in cachectic tumour-bearing hosts have made important contributions reducing the number of deaths and improving the quality of life. In recent years, leucine has demonstrated effective action in maintaining lean body mass by decreasing muscle protein degradation. Currently, there is a growing need to understand how leucine stimulates protein synthesis and acts protectively in a cachectic organism. Thus, this study aimed to assess the effects of a leucine-rich diet on protein degradation signalling in muscle over the course of tumour growth. Animals were distributed into four experimental groups, which did or did not receive 2×106 viable Walker-tumour cells. Some were fed a leucine-rich diet, and the groups were subsequently sacrificed at three different time points of tumour evolution (7th, 14th, and 21st days). Protein degradation signals, as indicated by ubiquitin-proteasome subunits (11S, 19S, and 20S) and pro- and anti-inflammatory cytokines, were analysed in all experimental groups. In tumour-bearing animals without nutritional supplementation (W7, W14, and W21 groups), we observed that the tumour growth promoted a concurrent decrease in muscle protein, a sharp increase in pro-inflammatory cytokines (TNFα, IL-6, and IFNγ), and a progressive increase in proteasome subunits (19S and 20S). Thus, the leucine-supplemented tumour-bearing groups showed improvements in muscle mass and protein content, and in this specific situation, the leucine-rich diet led to an increase on the day in cytokine profile and proteasome subunits mainly on the 14th day, which subsequently had a modulating effect on tumour growth on the 21st day. These results indicate that the presence of leucine in the diet may modulate important aspects of the proteasomal pathway in cancer cachexia and may prevent muscle wasting due to the decrease in the cachexia index.

Growth-related changes of phosphorus metabolites in VX-2 carcinoma implanted into rabbit thigh muscle: in vivo 31P MR spectroscopy

The purpose of this study was to evaluate the usefulness of in vivo 31P magnetic resonance spectroscopy (MRS) for monitoring changes in growth-related phosphate metabolite concentration and intracellular pH value in rabbit thigh muscle implanted with VX-2 carcinoma. The time-course magnetic resonance imaging (MRI) and in vivo 31P MRS were examined weekly in the course of 10 weeks following the onset of a VX-2 carcinoma implantation. The spectra were quantitatively analyzed to obtain vital information on the time course variation of the phosphorus metabolites and intracellular pH value according to the tumor growth. Elevation in the concentrations of phosphormonoesters (PME), inorganic phosphate (Pi), and phosphodiesters (PDE) was observed over the time course of 3-4 weeks after the implantation of VX2 carcinoma, while the rest of the metabolites, PCr and ATP tended to be constant. The concentration changes of PME, Pi, and PDE were positively correlated with the volumes of tumor necrosis. The intracellular pH values decreased with the time course of tumor growth and the volumes of tumor necrosis. In vivo 31P MRS is capable of non-invasive monitoring of intracellular pH values as well as the concentration changes of phosphate metabolites during tumor growth.

INOS expression and biosynthesis of nitric oxide metabolites in the course of tumor growth of different histogenesis

The dynamics of the production of nitric oxide (NO) metabolites: nitrites, nitrates, volatile nitrosamines and iNOS expression was studied in mice with subcutaneous transplanted, spontaneous and chemical- induced tumors. Tumor growth was accompanied by increased production of nitrites + nitrates in tumors or their release with urine that not dependent on tumor histotype. The total concentration of nitrites and nitrates in tumors reached micromolar levels characteristic of nitrosative stress. The ability of peritoneal macrophages + monocytes to generates nitrites was suppressed at the stage of intensive growth of the Lewis lung carcinoma, which may indicate a decrease in the cytotoxic properties of immune cells. The possibility of formation in the Erlich carcinoma of volative N-nitrosodimethylamine and N-nitrosodiethylamine compounds with pronounced carcinogenic properties was demonstrated. A positive expression of iNOS was revealed in some areas of lung carcinoma at all investigated time points using the immunohistochemical method. The lungs metastases were not stain or weakly stained. This may indicate selection of the cells with a low activity of iNOS migrating in the lungs.

CALCIUM SIGNALING IN TUMOR CELLS

The objective. The objective of this study was to investigate change in calcium maintenance of Ehrlich ascite adenocarcinoma cells in the course of tumor growth. Materials and methods. Cell viability was determined by counting apoptotic and necrotic cells under the fluorescence microscope. Intracellular calcium concentration was determined with the fluorescent probe 2,5 mM Fura-2AM. Relative microviscosity of membranes was estimated by fluorescence method using Pyrene. The activity of Ca-ATPase was assessed by the amount of inorganic phosphate produced during ATP hydrolysis. Results and discussions. We revealed that dynamics of Ehrlich ascite adenocarcinoma growth in our experiments was different from the commonly observed one. We noticed one peculiarity. The quantity of cells decreased on the day 12 after the tumor transplantation. This diminution was caused by mitotic activity lowering and by increase of apoptotic cell quantity the day before. Ehrlich ascite adenocarcinoma growth was accompanied by change in intracellular calcium maintenance which was independent of Ca-ATPase and cell membrane microviscosity. Conclusions. Thus, our experiments have shown the change in calcium concentration. Apparently Ca2+ activated proliferation. However calcium maintenance was settled by ROS. Possibly ROS supression in tumour on the day 12 was able to put down proliferative processes stimulation.

ID: 47: Nutritional L-leucine supplementation modulates muscle protein wasting and pro-inflammatory cytokines in Walker-256 tumour-bearing rats

Cancer cachexia is characterised by involuntary weight loss; the maintenance of lean body mass in cachectic hosts may contribute to a reduction in the number of deaths and an overall improvement in quality of life. The branched chain amino acid leucine affects cell signalling, thereby leading to an improvement in lean body mass by decreasing muscle protein degradation. We assess the effects of a leucine-rich diet on protein degradation signalling in muscle over the course of tumour growth. Adult Wistar rats were distributed into experimental groups according to whether a tumour or not was inoculated and whether or not a leucine-rich diet was provided. The animals were subsequently sacrificed at three different time points during tumour evolution (7th, 14th and 21st day after tumour implant). Protein degradation signalling, as indicated by ubiquitin–proteasome subunits (11S, 19S and 20S), and pro- and anti-inflammatory cytokines were analysed in each of the experimental groups. Tumour growth promoted a decrease in muscle protein, a sharp increase in pro-inflammatory cytokines (TNF α , IL-6 and IFN γ ) and a progressive increase in proteasome subunits (19S and 20S). Thus, the role of leucine in this specific situation reveals an increased process mainly on the 14th day after tumour implantation and a modulated action on the 21st day of tumour growth. The results indicate that leucine in the diet modulates some important key aspects of the proteasome pathway and inflammatory process in the cancer cachexia state.

Melanoma Induces, and Adenosine Suppresses, CXCR3-Cognate Chemokine Production and T-cell Infiltration of Lungs Bearing Metastatic-like Disease.

Despite immunogenicity, melanoma-specific vaccines have demonstrated minimal clinical efficacy in patients with established disease but enhanced survival when administered in the adjuvant setting. Therefore, we hypothesized that organs bearing metastatic-like melanoma may differentially produce T-cell chemotactic proteins over the course of tumor development. Using an established model of metastatic-like melanoma in lungs, we assessed the production of specific cytokines and chemokines over a time course of tumor growth, and we correlated chemokine production with chemokine receptor-specific T-cell infiltration. We observed that the interferon (IFN)-inducible CXCR3-cognate chemokines (CXCL9 and CXCL10) were significantly increased in lungs bearing minimal metastatic lesions, but chemokine production was at or below basal levels in lungs with substantial disease. Chemokine production was correlated with infiltration of the organ compartment by adoptively transferred CD8(+) tumor antigen-specific T cells in a CXCR3- and host IFNγ-dependent manner. Adenosine signaling in the tumor microenvironment (TME) suppressed chemokine production and T-cell infiltration in the advanced metastatic lesions, and this suppression could be partially reversed by administration of the adenosine receptor antagonist aminophylline. Collectively, our data demonstrate that CXCR3-cognate ligand expression is required for efficient T-cell access of tumor-infiltrated lungs, and these ligands are expressed in a temporally restricted pattern that is governed, in part, by adenosine. Therefore, pharmacologic modulation of adenosine activity in the TME could impart therapeutic efficacy to immunogenic but clinically ineffective vaccine platforms.

Poly (I: C) modulates the immunosuppressive activity of myeloid-derived suppressor cells in a murine model of breast cancer.

Polyinosinic-polycytidylic acid [Poly (I: C)], a ligand for Toll-like receptor (TLR-3), is used as an adjuvant to enhance anti-tumor immunity because of its prominent effects on CD8 T cells and NK cells. Myeloid-derived suppressor cells (MDSCs) are one of the main immunosuppressive factors in cancer, and their abnormal accumulation is correlated with the clinical stage of breast cancer and is an important mechanism of tumor immune evasion. Although Poly (I: C) is thought to have direct anti-tumor activity in different cell lines, its effect on immunosuppressive MDSCs in tumor-bearing animals has not been studied. 4T1-Luc, a metastatic breast cancer mouse cell line, was injected into the left flank of female BALB/c mice. Tumor-bearing mice were treated with i.p. injection of Poly (I: C) or PBS beginning on day 7 after tumor inoculation. WBCs and MDSCs were counted using coulter counter and stained for flow cytometry, respectively. Bioluminescent imaging was used to monitor tumor burden at multiple time points during the course of tumor growth. Poly (I: C) treatment led to a decrease in MDSC frequencies in BM, blood, and tumor compared to saline-treated control mice. Poly (I: C) treatment also abrogated the immunosuppressive function of MDSCs, concomitant with an increase in local T cell response of the immune system in a murine model of breast cancer. Poly (I: C) treatment decreases MDSC frequency and immunosuppressive function in 4T1-tumor-bearing hosts and effectively augments the activity of breast cancer immunotherapy.

Progressive loss of differentiated effector CD8 T cells infiltrating melanoma (TUM7P.1021)

Abstract CD8 tumor infiltrating lymphocytes (TIL) are critical for tumor control and their presence is a positive prognostic factor. Understanding CD8 TIL dysfunction is vital for developing cancer immunotherapies. Here, using a Granzyme B Cre ROSA YFP reporter system, we characterized the differentiation of CD8 T cells over the course of tumor growth using a murine melanoma model. At early stages of the CD8 T cell response (day 10 after tumor injection), the majority of the cells had differentiated to express Granzyme B (YFP+). However, over a period of four days, most of these effector cells were replaced by CD8+ T cells that had no evidence of effector differentiation. Concurrently, we found an increase in expression of the inhibitory receptor PD-1 in differentiated (YFP+) relative to non-differentiated (YFP-) CD8 TIL in late stage tumors. This suggests that there is both a loss of differentiated CD8 TIL and that the differentiated CD8 T cells that remain are more dysfunctional in late stage tumors. To provide insight into the cause and effect of this fluctuation in differentiation, we present data establishing the contribution of checkpoint inhibitory molecules and dendritic cell activation state in the loss of effector characteristics, and whether cytokine production and other effector activities correlate with the shift in effector differentiation status.

Comparison and analysis of the animal models used to study the effect of morphine on tumour growth and metastasis

The effect of opioids on tumour growth and metastasis has been debated for many years, with recent emphasis on the possibility that they might influence the rate of disease-free survival after tumour resection when used in the perioperative pain management of cancer surgery patients. The literature presents conflicting and inconclusive in vitro and in vivo data about the potential effect of opioids, especially morphine, on tumour growth and metastasis. To inform clinical practice, appropriate animal models are needed to test whether opioids alter the course of tumour growth and metastasis. Here, we review the literature on animal-based studies testing the effect of morphine on cancer so far, and analyse differences between the models used that may explain the discrepancies in published results. Such analysis should elucidate the role of opioids in cancer and help define ideal pre-clinical models to provide definitive answers. This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.

Expression of major histocompatibility complex class I-related chain A/B (MICA/B) in pancreatic carcinoma

Major histocompatibility complex class I-related chain A and B (MICA/B) are two stress-inducible ligands that bind to the immunoreceptor NKG2D and play an important role in mediating cytotoxicity of NK and T cells. Release of MIC molecules from the cell surface is thought to constitute an immune escape mechanism of tumor cells and thus could be associated with more aggressive course of tumor growth. In this study, we investigated the expression of MICA/B in ductal pancreatic carcinoma and serum in relation to tumor stage, differentiation and survival. MICA/B expression in tumor tissues and sera from patients with pancreatic cancer were analyzed by immunohistochemical staining (IHC), western blotting and ELISA, respectively. MICA/B expression was present in 17 of 22 (77%) of the tumors but not in normal pancreatic ductal epithelial cells. Poorly differentiated tumors showed more pronounced MICA/B expression compared to differentiated tumors, but did not correlate significantly to other tumor characteristics. MICA/B-negative tumors displayed significantly lower incidence of lymph node metastases (p<0.01), and less mortality within 3 years following resection (p<0.02). In conclusion, tissue levels of MICA/B expression were elevated in pancreatic cancer cells without elevated levels in serum, despite well-recognized acute phase reactants in serum. Poorly differentiated tumors showed high MICA/B expression, which was related to extended tumor lymph node metastases and less frequent long-term survival.