Key aspects for conception and construction of co-culture models of tumor-stroma interactions

The tumor microenvironment is crucial in the initiation and progression of cancers. The interplay between cancer cells and the surrounding stroma shapes the tumor biology and dictates the response to cancer therapies. Consequently, a better understanding of the interactions between cancer cells and different components of the tumor microenvironment will drive progress in developing novel, effective, treatment strategies. Co-cultures can be used to study various aspects of these interactions in detail. This includes studies of paracrine relationships between cancer cells and stromal cells such as fibroblasts, endothelial cells, and immune cells, as well as the influence of physical and mechanical interactions with the extracellular matrix of the tumor microenvironment. The development of novel co-culture models to study the tumor microenvironment has progressed rapidly over recent years. Many of these models have already been shown to be powerful tools for further understanding of the pathophysiological role of the stroma and provide mechanistic insights into tumor-stromal interactions. Here we give a structured overview of different co-culture models that have been established to study tumor-stromal interactions and what we have learnt from these models. We also introduce a set of guidelines for generating and reporting co-culture experiments to facilitate experimental robustness and reproducibility

Circulating Tissue Polypeptide-Specific Antigen in Pre-Diagnostic Pancreatic Cancer Samples

Simple Summary:& nbsp;Detecting cancer early significantly increases the chances of successful (surgical) treatment. Pancreatic cancer is one of the deadliest cancer forms, since it is usually discovered at a late and already spread stage. Finding biomarkers showing pancreatic cancer at an early stage is a possible approach to early detection and improved treatment. The aim of our study was to assess the potential of tissue polypeptide specific antigen (TPS) as a biomarker for early pancreatic cancer detection. We studied TPS levels in blood plasma samples from a population-based biobank in Vasterbotten, Sweden that were collected before individuals were diagnosed with pancreatic cancer. Although TPS levels are raised at diagnosis, this occurs late, and thus TPS does not seem to hold promise as an early detection marker for pancreatic cancer.& nbsp;Early detection of pancreatic ductal adenocarcinoma (PDAC) is challenging, and late diagnosis partly explains the low 5-year survival. Novel and sensitive biomarkers are needed to enable early PDAC detection and improve patient outcomes. Tissue polypeptide specific antigen (TPS) has been studied as a biomarker in PDAC diagnostics, and it has previously been shown to reflect clinical status better than the 'golden standard' biomarker carbohydrate antigen 19-9 (CA 19-9) that is most widely used in the clinical setting. In this cross-sectional case-control study using pre-diagnostic plasma samples, we aim to evaluate the potential of TPS as a biomarker for early PDAC detection. Furthermore, in a subset of individuals with multiple samples available at different time points before diagnosis, a longitudinal analysis was used. We assessed plasma TPS levels using enzyme-linked immunosorbent assay (ELISA) in 267 pre-diagnostic PDAC plasma samples taken up to 18.8 years before clinical PDAC diagnosis and in 320 matched healthy controls. TPS levels were also assessed in 25 samples at PDAC diagnosis. Circulating TPS levels were low both in pre-diagnostic samples of future PDAC patients and in healthy controls, whereas TPS levels at PDAC diagnosis were significantly increased (odds ratio 1.03; 95% confidence interval: 1.01-1.05) in a logistic regression model adjusted for age. In conclusion, TPS levels increase late in PDAC progression and hold no potential as a biomarker for early detection.Peer reviewe

Distinct populations of inflammatory fibroblasts and myofibroblasts in pancreatic cancer

Pancreatic stellate cells (PSCs) differentiate into cancer-associated fibroblasts (CAFs) that produce desmoplastic stroma, thereby modulating disease progression and therapeutic response in pancreatic ductal adenocarcinoma (PDA). However, it is unknown whether CAFs uniformly carry out these tasks or if subtypes of CAFs with distinct phenotypes in PDA exist. We identified a CAF subpopulation with elevated expression of alpha-smooth muscle actin (alphaSMA) located immediately adjacent to neoplastic cells in mouse and human PDA tissue. We recapitulated this finding in co-cultures of murine PSCs and PDA organoids, and demonstrated that organoid-activated CAFs produced desmoplastic stroma. The co-cultures showed cooperative interactions and revealed another distinct subpopulation of CAFs, located more distantly from neoplastic cells, which lacked elevated alphaSMA expression and instead secreted IL6 and additional inflammatory mediators. These findings were corroborated in mouse and human PDA tissue, providing direct evidence for CAF heterogeneity in PDA tumor biology with implications for disease etiology and therapeutic development

CA19-9 and apolipoprotein-A2 isoforms as detection markers for pancreatic cancer: a prospective evaluation.

Recently, we identified unique processing patterns of apolipoprotein A2 (ApoA2) in patients with pancreatic cancer. Our study provides a first prospective evaluation of an ApoA2 isoform ("ApoA2-ATQ/AT"), alone and in combination with carbohydrate antigen 19-9 (CA19-9), as an early detection biomarker for pancreatic cancer. We performed ELISA measurements of CA19-9 and ApoA2-ATQ/AT in 156 patients with pancreatic cancer and 217 matched controls within the European EPIC cohort, using plasma samples collected up to 60 months prior to diagnosis. The detection discrimination statistics were calculated for risk scores by strata of lag-time. For CA19-9, in univariate marker analyses, C-statistics to distinguish future pancreatic cancer patients from cancer-free individuals were 0.80 for plasma taken ≤6 months before diagnosis, and 0.71 for >6-18 months; for ApoA2-ATQ/AT, C-statistics were 0.62, and 0.65, respectively. Joint models based on ApoA2-ATQ/AT plus CA19-9 significantly improved discrimination within >6-18 months (C = 0.74 vs. 0.71 for CA19-9 alone, p = 0.022) and ≤ 18 months (C = 0.75 vs. 0.74, p = 0.022). At 98% specificity, and for lag times of ≤6, >6-18 or ≤ 18 months, sensitivities were 57%, 36% and 43% for CA19-9 combined with ApoA2-ATQ/AT, respectively, vs. 50%, 29% and 36% for CA19-9 alone. Compared to CA19-9 alone, the combination of CA19-9 and ApoA2-ATQ/AT may improve detection of pancreatic cancer up to 18 months prior to diagnosis under usual care, and may provide a useful first measure for pancreatic cancer detection prior to imaging

Fibroblast heterogeneity in the cancer wound

Fibroblasts regulate the structure and function of healthy tissues, participate transiently in tissue repair after acute inflammation, and assume an aberrant stimulatory role during chronic inflammatory states including cancer. Such cancer-associated fibroblasts (CAFs) modulate the tumor microenvironment and influence the behavior of neoplastic cells in either a tumor-promoting or tumor-inhibiting manner. These pleiotropic functions highlight the inherent plasticity of fibroblasts and may provide new avenues to understand and therapeutically intervene in malignancies. We discuss the emerging themes of CAF biology in the context of tumorigenesis and therapy

Basalmembranskollagener vid pankreascancer : utgör nya stromala tumörmarkörer och reglerar cancercellstillväxt

Background: Among the common malignancies, pancreatic cancer has the shortest long-term survival. The aggressive, rapid, and infiltrative growth pattern of pancreatic cancer, together with the lack of specific symptoms, often leads to late diagnosis. Metastases are frequently found at the time of diagnosis, which prevents curative surgical treatment. Good tumor markers would enable early detection, thus improving the prognosis. Unfortunately, no such markers are available in the clinic. The tumor stroma is defined as the non-malignant cells and the extracellular matrix (ECM) of a cancer. Pancreatic cancer is characterized by an abundant tumor stroma, rich in ECM proteins such as collagens, which have been shown to play important roles in tumor progression. Furthermore, pancreatic cancer cells produce large quantities of ECM proteins, especially the basement membrane (BM) protein type IV collagen. All epithelial cells are anchored to a BM, which must be degraded in order for an in situ cancer to become invasive. Matrix metalloproteinases (MMPs) are enzymes involved in BM degradation. In this thesis, the tumor stroma of pancreatic cancer is studied, focusing on the BM proteins type IV and type XVIII collagen, with the aim to clarify if the stroma could be a source of novel tumor markers for this form of cancer. Additionally, the role of type IV collagen produced by the cancer cells is studied. Methods: Expression patterns of type IV and type XVIII collagen, MMPs involved in collagen degradation, and collagen receptors (integrins) were studied by immunoflourescence in both normal and pancreatic cancer tissue, and in pancreatic cancer cell lines. Circulating plasma levels of type IV and type XVIII collagen and conventional tumor markers (TPS, Ca 19-9, CEA and Ca 125) were measured in controls and pancreatic cancer patients at the time of diagnosis and after treatment. The role of cancer cell produced type IV collagen was studied in human pancreatic cancer cell lines by functional blocking of integrin receptors (integrin a1, a2 and b1) and integrin-binding sites on type IV collagen, and by siRNA-induced down-regulation of type IV collagen synthesis. Proliferation was analyzed by a luminescence based cell viability assay, migration by time-lapse microscopy, and apoptosis by M30-neoepitope detection. Results: MMPs involved in BM degradation were upregulated in pancreatic cancer tissue. The expression of type XVIII collagen shifted from a general BM expression pattern in normal tissue, to mainly being found in the tumor vasculature in pancreatic cancer. Type IV collagen, on the other hand, remained highly expressed in the vicinity of the cancer cells. The a1, a2, and b1 integrin receptors were highly expressed at the cancer cell surface. Both down-regulation of type IV collagen synthesis and blocking the integrin/type IV collagen interaction decreased cell proliferation and migration. The proliferative capacity was rescued by the addition of exogenous type IV collagen. Furthermore, the circulating levels of both type IV and type XVIII collagen were increased in pancreatic cancer patients at the time of diagnosis compared to controls. After treatment, the levels were normalized for type XVIII collagen, whereas the levels of type IV collagen remained high after surgery. High postoperative levels of type IV collagen were associated with short overall survival. A similar association to short survival was found for preoperative type XVIII collagen levels. No such associations to survival could be detected for the conventional markers.   Conclusion: The results of this thesis show that type IV and type XVIII collagens can serve as tumor markers for pancreatic cancer with advantages compared to conventionally used markers. Additionally, evidence is provided of an autocrine loop, involving type IV collagen and its integrin receptors, with importance for retaining a proliferative and migratory phenotype in pancreatic cancer cells

Distinct populations of inflammatory fibroblasts and myofibroblasts in pancreatic cancer

Pancreatic stellate cells (PSCs) differentiate into cancer-associated fibroblasts (CAFs) that produce desmoplastic stroma, thereby modulating disease progression and therapeutic response in pancreatic ductal adenocarcinoma (PDA). However, it is unknown whether CAFs uniformly carry out these tasks or if subtypes of CAFs with distinct phenotypes in PDA exist. We identified a CAF subpopulation with elevated expression of a-smooth muscle actin (alpha SMA) located immediately adjacent to neoplastic cells in mouse and human PDA tissue. We recapitulated this finding in co-cultures of murine PSCs and PDA organoids, and demonstrated that organoid-activated CAFs produced desmoplastic stroma. The co-cultures showed cooperative interactions and revealed another distinct subpopulation of CAFs, located more distantly from neoplastic cells, which lacked elevated aSMA expression and instead secreted IL6 and additional inflammatory mediators. These findings were corroborated in mouse and human PDA tissue, providing direct evidence for CAF heterogeneity in PDA tumor biology with implications for disease etiology and therapeutic development

Basalmembranskollagener vid pankreascancer : utgör nya stromala tumörmarkörer och reglerar cancercellstillväxt

Background: Among the common malignancies, pancreatic cancer has the shortest long-term survival. The aggressive, rapid, and infiltrative growth pattern of pancreatic cancer, together with the lack of specific symptoms, often leads to late diagnosis. Metastases are frequently found at the time of diagnosis, which prevents curative surgical treatment. Good tumor markers would enable early detection, thus improving the prognosis. Unfortunately, no such markers are available in the clinic. The tumor stroma is defined as the non-malignant cells and the extracellular matrix (ECM) of a cancer. Pancreatic cancer is characterized by an abundant tumor stroma, rich in ECM proteins such as collagens, which have been shown to play important roles in tumor progression. Furthermore, pancreatic cancer cells produce large quantities of ECM proteins, especially the basement membrane (BM) protein type IV collagen. All epithelial cells are anchored to a BM, which must be degraded in order for an in situ cancer to become invasive. Matrix metalloproteinases (MMPs) are enzymes involved in BM degradation. In this thesis, the tumor stroma of pancreatic cancer is studied, focusing on the BM proteins type IV and type XVIII collagen, with the aim to clarify if the stroma could be a source of novel tumor markers for this form of cancer. Additionally, the role of type IV collagen produced by the cancer cells is studied. Methods: Expression patterns of type IV and type XVIII collagen, MMPs involved in collagen degradation, and collagen receptors (integrins) were studied by immunoflourescence in both normal and pancreatic cancer tissue, and in pancreatic cancer cell lines. Circulating plasma levels of type IV and type XVIII collagen and conventional tumor markers (TPS, Ca 19-9, CEA and Ca 125) were measured in controls and pancreatic cancer patients at the time of diagnosis and after treatment. The role of cancer cell produced type IV collagen was studied in human pancreatic cancer cell lines by functional blocking of integrin receptors (integrin a1, a2 and b1) and integrin-binding sites on type IV collagen, and by siRNA-induced down-regulation of type IV collagen synthesis. Proliferation was analyzed by a luminescence based cell viability assay, migration by time-lapse microscopy, and apoptosis by M30-neoepitope detection. Results: MMPs involved in BM degradation were upregulated in pancreatic cancer tissue. The expression of type XVIII collagen shifted from a general BM expression pattern in normal tissue, to mainly being found in the tumor vasculature in pancreatic cancer. Type IV collagen, on the other hand, remained highly expressed in the vicinity of the cancer cells. The a1, a2, and b1 integrin receptors were highly expressed at the cancer cell surface. Both down-regulation of type IV collagen synthesis and blocking the integrin/type IV collagen interaction decreased cell proliferation and migration. The proliferative capacity was rescued by the addition of exogenous type IV collagen. Furthermore, the circulating levels of both type IV and type XVIII collagen were increased in pancreatic cancer patients at the time of diagnosis compared to controls. After treatment, the levels were normalized for type XVIII collagen, whereas the levels of type IV collagen remained high after surgery. High postoperative levels of type IV collagen were associated with short overall survival. A similar association to short survival was found for preoperative type XVIII collagen levels. No such associations to survival could be detected for the conventional markers.   Conclusion: The results of this thesis show that type IV and type XVIII collagens can serve as tumor markers for pancreatic cancer with advantages compared to conventionally used markers. Additionally, evidence is provided of an autocrine loop, involving type IV collagen and its integrin receptors, with importance for retaining a proliferative and migratory phenotype in pancreatic cancer cells

Key aspects for conception and construction of co-culture models of tumor-stroma interactions

The tumor microenvironment is crucial in the initiation and progression of cancers. The interplay between cancer cells and the surrounding stroma shapes the tumor biology and dictates the response to cancer therapies. Consequently, a better understanding of the interactions between cancer cells and different components of the tumor microenvironment will drive progress in developing novel, effective, treatment strategies. Co-cultures can be used to study various aspects of these interactions in detail. This includes studies of paracrine relationships between cancer cells and stromal cells such as fibroblasts, endothelial cells, and immune cells, as well as the influence of physical and mechanical interactions with the extracellular matrix of the tumor microenvironment. The development of novel co-culture models to study the tumor microenvironment has progressed rapidly over recent years. Many of these models have already been shown to be powerful tools for further understanding of the pathophysiological role of the stroma and provide mechanistic insights into tumor-stromal interactions. Here we give a structured overview of different co-culture models that have been established to study tumor-stromal interactions and what we have learnt from these models. We also introduce a set of guidelines for generating and reporting co-culture experiments to facilitate experimental robustness and reproducibility