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Pericyte sGC signaling dictates tumor vessel formation and tumor microenvironment

ABSTRACT: Pericytes and endothelial cells (ECs) are building blocks of blood vessels. While the contributions of ECs to tumor angiogenesis and the tumor microenvironment are well established and multiple drugs that targeting ECs have been developed for clinic use to treat cancers, the underlying mechanisms of pericyte in supporting tumor vessel and in shaping tumor microenvironment remains largely unexplored and no pericyte targeting strategies have been approved yet. This study employs targeted deletion of the NO receptor sGC in pericytes and utilizes single-cell RNA sequencing to elucidate its impact on the tumor microenvironment. The results unveil a disruptive effect on EC-pericyte interactions, subsequently impeding Notch-mediated intercellular crosstalk and prompting extensive transcriptomic reprogramming in both cell types. This vascular alteration further relays to neighboring cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs) through paracrine signaling, collectively suppressing tumor growth. Importantly, the inhibition of pericyte sGC has limited influence on quiescent vessels but significantly sensitizes angiogenic vessels to anti-angiogenic treatment. In conclusion, this study underscores the vital role of pericytes in governing tumor vessels and the tumor microenvironment, suggesting that targeting pericyte sGC holds promise for enhancing anti-angiogenic therapy.

ORGANISM(S): Mus musculus

PROVIDER: GSE243313 | GEO | 2024/02/01

REPOSITORIES: GEO

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Project description:Objective: Insights about differences in tumor vasculature and how it reacts to VEGF inhibition is limited, but nevertheless of major relevance to anti-angiogenic therapy. In this study we therefore characterize the effect of bevacizumab combined with chemoradiotherapy (CRT), and explore molecular and genetic markers for response prediction to this combination treatment. Material and Methods: In an academic multicentric randomized phase II study, patients with advanced rectal cancer have been treated with bevacizumab (5mg/kg) in combination with capecitabine (1650mg/m2/day) and radiotherapy (45Gy; 1.8Gy/day) with (50mg/m2) or without oxaliplatin prior to surgery. Of 59 patients, tumor tissue and blood samples were collected before treatment and after the first loading dose of bevacizumab but before CRT (week 3). First, cDNA micro-arrays were performed on the biopsies to investigate differences in gene expression of tumors from patients with and without a pathological complete response (pCR) before start of treatment and to identify biological processes affected by bevacizumab delivery. The paraffin embedded tissue was stained for blood vessels (CD31/CD34) combined with Î±-SMA (pericytes) and CA-IX (hypoxia). To explore candidate blood-based biomarkers ELISAâs were performed for PDGF-AA, PDGF-BB, THBS-1, IL-8, CYR61 and Ang-2. The expression of all markers was correlated with the pathological response of the patients. Results: Differences in tumoral gene expression are observed between patients with and without a pCR, with the first response group presenting a more angiogenic phenotype before start of treatment and changes in angiogenic processes after bevacizumab delivery. One dose of bevacizumab leads to a decrease in the number of pericyte covered blood vessels, a decrease in circulating PDGF-AA, PDGF-BB and Thrombospondin-1. Patients showing a pCR having less pericyte covered blood vessels, more hypoxia, and less circulating PDGF-BB compared to patients who did not have a pCR after bevacizumab treatment with chemoradiation and bevacizumab. Conclusions: The translational data demonstrate that tumors with an angiogenic expression profile respond better to bevacizumab combined with CRT and points towards a possible role for PDGF, CA-IX and pericyte covered blood vessels for the early response prediction to this treatment. Our findings suggest a role for mural cell recruitment and vessel maturation for the susceptibility of the tumor vasculature to bevacizumab treatment. Further validation of our biological observations and hypothesis generating data in randomized trials is needed. This study involves samples of patients enrolled in the AXEbeam trail that were analysed by Primeview microarray (Affymetrix). Biopsies were taken at two different timepoints: before treatment (tumor and normal mucosa) and after the first loading dose of bevacizumab but before chemoradiation (only tumor, week 3). Patients were classified into two groups: with a complete pathological response at time of surgery (Responders=R) or non-responders (NR). For the responders, we collected 21 samples in total (7 tumor samples and 8 normal mucosa samples taken before treatment and 6 tumor samples collected at week 3). From the non-responders we had 26 samples in total (9 tumor and 10 mucosa samples before treatment and 7 tumor samples at week 3 after a single dose of bevacizumab). Microarrays were run in two batches (15xxx versus 16xxx CEL file samples; indicated in the description field). Three samples (NJ 04/003 T1, RVS 09/002 M and NJ 04/003 W3) were put twice on the array (15897+16789; 15893+16790; 15898+16791) to verify and exclude batch effects. Please note that, due to these three technical repeats the total number of microarray CEL files is 50 (21 Responders, 26 Non-responders and 3 repeats).

Project description:Background: The differentiation of pericytes into myofibroblasts causes microvascular degeneration, extracellular matrix (ECM) accumulation, and tissue stiffening, characteristics of fibrotic diseases. It is unclear how pericyte-myofibroblast differentiation is regulated in the microvascular environment. Our previous study established a novel two-dimensional platform for coculturing microvascular endothelial cells (ECs) and pericytes derived from the same tissue. This study investigated how ECM stiffness regulated microvascular ECs, pericytes, and their interactions. Methods: Primary microvessels were cultured in the TGM2D medium. Stiff ECM was prepared by incubating ECM solution in regular culture dishes for one hour followed by PBS wash. Soft ECM with Young’s modulus of approximately 6 kPa was used unless otherwise noted. Bone grafts were prepared from the rat skull. Immunostaining, RNA sequencing, qRT-PCR, western blotting, and knockdown experiments were performed on the cells. Results: Primary microvascular pericytes differentiated into myofibroblasts (NG2+αSMA+) on stiff ECM, even with the TGFβ signaling inhibitor A83-01. Soft ECM and A83-01 cooperatively maintained microvascular stability while inhibiting pericyte-myofibroblast differentiation (NG2+αSMA-/low). We thus defined two pericyte subpopulations: primary (NG2+αSMA-/low) and activated (NG2+αSMA+) pericytes. Soft ECM promoted microvascular regeneration and inhibited fibrosis in bone graft transplantation in vivo. As Integrins are the major mechanosensor, we performed qRT-PCR screening of Integrin family members selected from RNA sequencing data. We found that Integrin β1 (Itgb1) was the major subunit downregulated by soft ECM and A83-01 treatment. Knocking down Itgb1 suppressed myofibroblast differentiation on stiff ECM. Interestingly, ITGB1 phosphorylation (Y783) was mainly located on microvascular ECs on stiff ECM, which promoted EC secretion of paracrine factors, including CTGF, to induce pericyte-myofibroblast differentiation. CTGF knockdown or monoclonal antibody treatment partially reduced myofibroblast differentiation, implying the participation of multiple pathways in fibrosis formation. Conclusions: Microvascular ECs mediate ECM stiffness-induced pericyte-myofibroblast differentiation through paracrine signaling.

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Pericyte sGC signaling dictates tumor vessel formation and tumor microenvironment

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