Non-cancerous Stroma Research Articles

A Mathematical Model of Stroma-Supported Allometric Tumor Growth.

Mounting empirical research suggests that the stroma, or interface between healthy and cancerous tissue, is a critical determinate of cancer invasion. At the same time, a cancer cell's location and potential to proliferate can influence its sensitivity to cancer treatments. In this paper, we use ordinary differential equations to develop spatially structured models for solid tumors wherein the growth of tumor components is coordinated. The model tumors feature two components, a proliferating peripheral growth region, which potentially includes a mix of cancerous and noncancerous stroma cells, and a solid tumor core. Mathematical and numerical analysis are used to investigate how coordinated expansion of the tumor growth region and core can influence overall growth dynamics in a variety of tumor types. Model assumptions, which are motivated by empirical and in silico solid tumor research, are evaluated through comparison to tumor volume data and existing models of tumor growth.

Stromal-driven and Amyloid \u03b2-dependent induction of neutrophil extracellular traps modulates tumor growth

Tumors consist of cancer cells and a network of non-cancerous stroma. Cancer-associated fibroblasts (CAF) are known to support tumorigenesis, and are emerging as immune modulators. Neutrophils release histone-bound nuclear DNA and cytotoxic granules as extracellular traps (NET). Here we show that CAFs induce NET formation within the tumor and systemically in the blood and bone marrow. These tumor-induced NETs (t-NETs) are driven by a ROS-mediated pathway dependent on CAF-derived Amyloid β, a peptide implicated in both neurodegenerative and inflammatory disorders. Inhibition of NETosis in murine tumors skews neutrophils to an anti-tumor phenotype, preventing tumor growth; reciprocally, t-NETs enhance CAF activation. Mirroring observations in mice, CAFs are detected juxtaposed to NETs in human melanoma and pancreatic adenocarcinoma, and show elevated amyloid and β-Secretase expression which correlates with poor prognosis. In summary, we report that CAFs drive NETosis to support cancer progression, identifying Amyloid β as the protagonist and potential therapeutic target.

The ratio of cancer cells to stroma within the invasive area is a histologic prognostic parameter of lung adenocarcinoma

ObjectivesThis study evaluated whether the proportion of cancer cells to non-cancerous stroma within the invasive area is associated with the prognosis of patients with lung adenocarcinoma. Materials and methodsA total of 127 patients with lung adenocarcinomas with tumors larger than 3 cm in total size were enrolled in this study. We classified the tumors according to the ratio of area occupied by cancer cells within the invasive area (Type A: more than 50% of the invasive area, Type B: 10–50%, and Type C: less than 10%) and analyzed the clinicopathological differences between Types A, B, and C. ResultsThe invasive size of Type A tumors (n = 35) was significantly larger than those of the other two tumor types; however, there was no significant difference in the invasive size between Types B (n = 65) and C (n = 25) tumors. The recurrence-free survival time of patients with Type C tumors was significantly longer than those of patients with Type A and B (P < .001) tumors. Multivariate analysis revealed that Type C tumor was an independent favorable prognostic factor (P = .037) but that invasive size was not. The invasive area of Type C tumor was composed of a significantly higher proportion of collapsed elastic fibers than the invasive areas of Type A and B tumors (P < .001). ConclusionA lower cancer cell to stroma ratio within the invasive area could be a significant prognostic factor in lung adenocarcinoma, suggesting that not only the invasive size but also the invasive character might be an important histologic prognostic parameter.

Analysis of Somatic DNA Methylation Alterations of Genes Encoding Cell Surface Metallopeptidases in Colorectal Cancer.

The genome of cancer cells accumulates numerous genetic and epigenetic somatic alterations ultimately conferring capabilities for unrestrained growth, invasion of local tissues, migration, and colonization of distant organs. Many of these new capabilities require the disruption of the cell-to-cell interactions between the cancer cell and its microenvironment. These interactions are mediated, among other factors, by the activity of extracellular enzymes that reshape not only the extracellular compartment of the cancer cells but also that of the neighboring non-cancerous stroma cells. Cell surface metallopeptidases play a crucial role in this process, by cleaving and modifying fundamental components of the extracellular compartment. The transcriptional profile of cell surface metallopeptidases becomes deregulated in several human cancers by genetic and epigenetic alterations, contributing to the tumor phenotype. In this article, we describe two common strategies to analyze somatic epigenetic alterations of cell surface metallopeptidases, i.e., high-resolution single locus analysis and high-throughput multi-loci analysis, presenting several illustrative analyses performed on our CRC collection. These analyses demonstrate that cell surface metallopeptidases, particularly those belonging to the ADAMTS gene family, frequently undergo somatic DNA hypermethylation in CRC suggesting the existence of an underlying mechanism or a strong selection process favoring the transcriptional silencing of these genes.

A Mimic of the Tumor Microenvironment: A Simple Method for Generating Enriched Cell Populations and Investigating Intercellular Communication.

Understanding the early heterotypic interactions between cancer cells and the surrounding non-cancerous stroma is important in elucidating the events leading to stromal activation and establishment of the tumor microenvironment (TME). Several in vitro and in vivo models of the TME have been developed; however, in general these models do not readily permit isolation of individual cell populations, under non-perturbing conditions, for further study. To circumvent this difficulty, we have employed an in vitro TME model using a cell growth substrate consisting of a permeable microporous membrane insert that permits simple generation of highly enriched cell populations grown intimately, yet separately, on either side of the insert's membrane for extended co-culture times. Through use of this model, we are capable of generating greatly enriched cancer-associated fibroblast (CAF) populations from normal diploid human fibroblasts following co-culture (120 hr) with highly metastatic human breast carcinoma cells, without the use of fluorescent tagging and/or cell sorting. Additionally, by modulating the pore-size of the insert, we can control for the mode of intercellular communication (e.g., gap-junction communication, secreted factors) between the two heterotypic cell populations, which permits investigation of the mechanisms underlying the development of the TME, including the role of gap-junction permeability. This model serves as a valuable tool in enhancing our understanding of the initial events leading to cancer-stroma initiation, the early evolution of the TME, and the modulating effect of the stroma on the responses of cancer cells to therapeutic agents.

The reverse Warburg effect and 18F-FDG uptake in non-small cell lung cancer A549 in mice: a pilot study.

The purpose of this study was to observe the effect of fasting and feeding on (18)F-FDG uptake in a mouse model of human non-small cell lung cancer. In in vivo studies, (18)F-FDG small-animal PET scans were acquired in 5 mice bearing non-small cell lung cancer A549 xenografts on each flank with continuous feeding and after overnight fasting to observe the changes in intratumoral distribution of (18)F-FDG and tumor (18)F-FDG standardized uptake value (SUV). In ex vivo studies, intratumoral spatial (18)F-FDG distribution assessed by autoradiography was compared with the tumor microenvironment (including hypoxia by pimonidazole and stroma by hematoxylin and eosin stain). Five overnight-fasted mice and 5 fed mice with A549 tumors were observed. Small-animal PET scans were obtained in fed animals on day 1 and in the same animals after overnight fasting; the lapse was approximately 14 h. Blood glucose concentration after overnight fasting was not different from fed mice (P = 0.42), but body weight loss was significant after overnight fasting (P = 0.001). Intratumoral distribution of (18)F-FDG was highly heterogeneous in all tumors examined, and change in spatial intratumoral distribution of (18)F-FDG between 2 sets of PET images from the same mouse was remarkably different in all mice. Tumor (18)F-FDG mean SUV and maximum SUV were not significantly different between fed and fasted animals (all P > 0.05, n = 10). Only tumor mean SUV weakly correlated with blood glucose concentration (R(2) = 0.17, P = 0.03). In ex vivo studies, in fasted mice, there was spatial colocalization between high levels of (18)F-FDG uptake and pimonidazole-binding hypoxic cancer cells; in contrast, pimonidazole-negative normoxic cancer cells and noncancerous stroma were associated with low (18)F-FDG uptake. However, high (18)F-FDG uptake was frequently observed in noncancerous stroma of tumors but rarely in viable cancer cells of the tumors in fed animals. Host dietary status may play a key role in intratumoral distribution of (18)F-FDG. In the fed animals, (18)F-FDG accumulated predominantly in noncancerous stroma in the tumors, that is, reverse Warburg effect. In contrast, in fasted status, (18)F-FDG uptake was found in hypoxic cancer cells component (Pasteur effect). Our findings may provide a better understanding of competing cancer glucose metabolism hypotheses: the Warburg effect, reverse Warburg effect, and Pasteur effect.

Overexpression of the Lung Cancer-Prognostic miR-146b MicroRNAs Has a Minimal and Negative Effect on the Malignant Phenotype of A549 Lung Cancer Cells

IntroductionExpression levels of miR-146b-5p and -3p microRNAs in human non-small cell lung cancer (NSCLC) are associated with recurrence of the disease after surgery. To understand this, the effect of miR-146b overexpression was studied in A549 human lung cancer cells.MethodsA549 cells, engineered with lentiviruses to overexpress the human pre-miR-146b precursor microRNA, were examined for proliferation, colony formation on plastic surface and in soft agar, migration and invasiveness in cell culture and in vivo in mice, chemosensitivity to cisplatin and doxorubicin, and global gene expression. miR-146b expressions were assessed in microdissected stroma and epithelia of human NSCLC tumors. Association of miR-146b-5p and -3p expression in early stage NSCLC with recurrence was analyzed.Principal FindingsA549 pre-miR-146b-overexpressors had 3–8-fold higher levels of both miR-146b microRNAs than control cells. Overexpression did not alter cellular proliferation, chemosensitivity, migration, or invasiveness; affected only 0.3% of the mRNA transcriptome; and, reduced the ability to form colonies in vitro by 25%. In human NSCLC tumors, expression of both miR-146b microRNAs was 7–10-fold higher in stroma than in cancerous epithelia, and higher miR-146b-5p but lower -3p levels were predictive of recurrence.ConclusionsOnly a minimal effect of pre-miR-146b overexpression on the malignant phenotype was seen in A549 cells. This could be because of opposing effects of miR-146b-5p and -3p overexpression as suggested by the conflicting recurrence-predictive values of the two microRNAs, or because miR-146b expression changes in non-cancerous stroma and not cancerous epithelia of tumors are responsible for the prognostic value of miR-146b.

Components of the Hematopoietic Compartments in Tumor Stroma and Tumor-Bearing Mice

Solid tumors are composed of cancerous cells and non-cancerous stroma. A better understanding of the tumor stroma could lead to new therapeutic applications. However, the exact compositions and functions of the tumor stroma are still largely unknown. Here, using a Lewis lung carcinoma implantation mouse model, we examined the hematopoietic compartments in tumor stroma and tumor-bearing mice. Different lineages of differentiated hematopoietic cells existed in tumor stroma with the percentage of myeloid cells increasing and the percentage of lymphoid and erythroid cells decreasing over time. Using bone marrow reconstitution analysis, we showed that the tumor stroma also contained functional hematopoietic stem cells. All hematopoietic cells in the tumor stroma originated from bone marrow. In the bone marrow and peripheral blood of tumor-bearing mice, myeloid populations increased and lymphoid and erythroid populations decreased and numbers of hematopoietic stem cells markedly increased with time. To investigate the function of hematopoietic cells in tumor stroma, we co-implanted various types of hematopoietic cells with cancer cells. We found that total hematopoietic cells in the tumor stroma promoted tumor development. Furthermore, the growth of the primary implanted Lewis lung carcinomas and their metastasis were significantly decreased in mice reconstituted with IGF type I receptor-deficient hematopoietic stem cells, indicating that IGF signaling in the hematopoietic tumor stroma supports tumor outgrowth. These results reveal that hematopoietic cells in the tumor stroma regulate tumor development and that tumor progression significantly alters the host hematopoietic compartment.

MR quantification of abnormal stromal enhancement in the periphery of invasive breast tumors

636 Background: In dynamic contrast-enhanced MRI (DCEMRI), properties of tissue microvasculature and overall vascularity can be quantified using kinetics of contrast enhancement. It has been shown that areas with high signal enhancement ratio (SER) were significantly correlated with high tumor vascularity, and that mean SER in nearby non-cancerous breast stroma was significantly associated with disease free survival. No universally accepted methods exist to determine the optimal extent of histologically normal breast tissue to treat. Although a relationship between normal tissue SER and recurrence has been observed, the spatial relationship of enhancement within the non-cancerous stroma with respect to proximity of the tumor has not been shown. We hypothesized that abnormalities in vasculature exist within the histologically normal breast stroma that can be detected by measuring changes in enhancement intensity. Methods: We performed a secondary analysis of pre-treatment DCEMRI data from 27 invasive breast cancer patients. An automated, user-independent program was used to segment breast tissue from all other structures. A SER threshold was set to identify invasive tumor regions, and a tumor proximity map was generated giving the 3D distance of each normal breast tissue voxel to the nearest tumor voxel. A percent enhancement (PE) map was calculated for the normal stroma using the signal intensity change between the pre-contrast and post-contrast images. The proximity and PE maps were then combined to measure breast tissue enhancement at various distances from the tumor. Results: PE levels in normal breast tissue situated within 2 cm of the tumor region were significantly higher than at all more distant regions. Pairwise comparisons with Turkey's adjusted p-values indicated that the mean PE at 0 cm-1 cm is significantly higher than all other distant levels (p = &lt; 0.0001) and the mean PE at 1 cm-2 cm is significantly higher than 5 cm-6 cm (p = 0.006). Conclusions: Here, we show that the normal-appearing breast stroma within 0 cm to 2 cm of a primary tumor exhibits higher enhancement levels than stroma located far from the tumor. These results suggest that tissue surrounding the tumor region may contain tumor-related angiogenesis. These findings could help personalize surgery and radiation techniques. No significant financial relationships to disclose.

Human prostate stromal cells stimulate increased PSA production in DHEA-treated prostate cancer epithelial cells

Dehydroepiandrosterone (DHEA) is commonly used as a dietary supplement and may affect prostate pathophysiology when metabolized to androgens and/or estrogens. Human prostate LAPC-4 cancer cells with a wild type androgen receptor (AR) were treated with DHEA, androgens dihydrotestosterone (DHT), T, or R1881), and E 2 and assayed for prostate specific antigen (PSA) protein and gene expression. In LAPC-4 monocultures, DHEA and E 2 induced little or no increase in PSA protein or mRNA expression compared to androgen-treated cells. When prostate cancer-associated (6S) stromal cells were added in coculture, DHEA stimulated LAPC-4 cell PSA protein secretion to levels approaching induction by DHT. Also, DHEA induced 15-fold more PSA mRNA in LAPC-4 cocultures than in monocultures. LAPC-4 proliferation was increased 2–3-fold when cocultured with 6S stromal cells regardless of hormone treatment. DHEA-treated 6S stromal cells exhibited a dose- and time-dependent increase in T secretion, demonstrating stromal cell metabolism of DHEA to T. Coculture with non-cancerous stroma did not induce LAPC-4 PSA production, suggesting a differential modulation of DHEA effect in a cancer-associated prostate stromal environment. This coculture model provides a research approach to reveal detailed endocrine, intracrine, and paracrine signaling between stromal and epithelial cells that regulate tissue homeostasis within the prostate, and the role of the tumor microenvironment in cancer progression.

Matrix metalloproteinase 9 in mucosally invasive gastric cancer.

BACKGROUND: Matrix metalloproteinase 9 (MMP-9) facilitates tumor invasion and metastasis via basement membrane degradation. Control of MMP-9 production by cancer-stromal cell interactions in these processes has been observed.METHODS: We measured plasma MMP-9 concentrations, using a one-step sandwich enzyme immunoassay, and also immunohistochemically localized MMP-9 in patients with small gastric cancers limited to the mucosa. The cancers were classified as intraepithelial tumor (Tis) and T1 disease according to the tumor-node-metastasis (TNM) classification of the International Union Against Cancer.RESULTS: Patients with T1 disease had a higher positivity rate for and mean value of MMP-9 than patients with Tis disease. In T1 tumors, MMP-9 expression determined immunohistochemically, was greater in cells in cancer stroma than in cells in noncancerous stroma, a situation found in only a few Tis tumors.CONCLUSIONS: These results suggest that MMP-9 is related to the initial step of gastric cancer invasion.