Isolation of Normal and Cancer-Associated Fibroblasts

Cancer-Associated Fibroblasts as the "Architect" of the Lung Cancer Immune Microenvironment: Multidimensional Roles and Synergistic Regulation with Radiotherapy

Cancer-associated fibroblasts (CAFs), as the "architect" of the immune microenvironment in lung cancer, play a multidimensional role in tumor progression and immune regulation. In this review, we summarize the heterogeneity of the origin and the molecular phenotype of CAFs in lung cancer, and explore the complex interactions between CAFs and multiple components of the tumor microenvironment, including the regulatory relationships with innate immune cells (e.g., tumor-associated macrophages, tumor-associated neutrophils), adaptive immune cells (e.g., T cells), and extracellular matrix (ECM). CAFs significantly influence tumor progression and immunomodulation through the secretion of cytokines, remodeling of the ECM, and the regulation of immune cell function significantly affects the immune escape and treatment resistance of tumors. In addition, this review also deeply explored the synergistic regulatory relationship between CAF and radiotherapy, revealing the key role of CAF in radiotherapy-induced remodeling of the immune microenvironment, which provides a new perspective for optimizing the comprehensive treatment strategy of lung cancer. By comprehensively analyzing the multidimensional roles of CAF and its interaction with radiotherapy, this review aims to provide a theoretical basis for the precise regulation of the immune microenvironment and clinical treatment of lung cancer.

Cancer-associated fibroblasts: a versatile mediator in tumor progression, metastasis, and targeted therapy

Tumor microenvironment (TME) has been demonstrated to play a significant role in tumor initiation, progression, and metastasis. Cancer-associated fibroblasts (CAFs) are the major component of TME and exhibit heterogeneous properties in their communication with tumor cells. This heterogeneity of CAFs can be attributed to various origins, including quiescent fibroblasts, mesenchymal stem cells (MSCs), adipocytes, pericytes, endothelial cells, and mesothelial cells. Moreover, single-cell RNA sequencing has identified diverse phenotypes of CAFs, with myofibroblastic CAFs (myCAFs) and inflammatory CAFs (iCAFs) being the most acknowledged, alongside newly discovered subtypes like antigen-presenting CAFs (apCAFs). Due to these heterogeneities, CAFs exert multiple functions in tumorigenesis, cancer stemness, angiogenesis, immunosuppression, metabolism, and metastasis. As a result, targeted therapies aimed at the TME, particularly focusing on CAFs, are rapidly developing, fueling the promising future of advanced tumor-targeted therapy.

Patient-Derived Exosomes as siRNA Carriers in Ovarian Cancer Treatment

RNA interference is a powerful gene-silencing tool with potential clinical applications. However, its therapeutic use is challenging because suitable carriers are unavailable. Exosomes are stable small endogenous vesicles that can transport functional molecules to target cells, making them ideal small interfering RNA (siRNA) carriers. Herein, we elucidated the therapeutic potential of patient-derived exosomes as an siRNA carrier for ovarian cancer (OC) treatment. The exosomes were extracted from the culture medium of primary fibroblasts collected from the omentum of patients with OC during surgery. MET proto-oncogene, receptor tyrosine kinase (MET) was selected for gene silencing, c-Met siRNAs were synthesized and loaded into the exosomes (Met-siExosomes) via electroporation, and the treatment effect of the Met-siExosomes was assessed in vitro and in vivo. The Met-siExosomes downregulated the c-Met protein levels and inhibited OC cell proliferation, migration, and invasion. In xenograft experiments using SKOV3-13 and ES-2 cells, Met-siExosomes were selectively extracted from peritoneally disseminated tumors. Intraperitoneal treatment suppressed the c-Met downstream targets in cancer cells and prolonged mouse survival. The synthesized siRNAs were successfully and selectively delivered via the exosomes to intraperitoneally disseminated tumors. As patients with OC routinely undergo omentectomy and abundant fibroblasts can be easily collected from the omentum, patient-derived exosomes may represent a promising therapeutic siRNA carrier to treat OC.

"Pulsed Hypoxia" Gradually Reprograms Breast Cancer Fibroblasts into Pro-Tumorigenic Cells via Mesenchymal-Epithelial Transition

Hypoxia arises in most growing solid tumors and can lead to pleotropic effects that potentially increase tumor aggressiveness and resistance to therapy through regulation of the expression of genes associated with the epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET). The main goal of the current work was to obtain and investigate the intermediate phenotype of tumor cells undergoing the hypoxia-dependent transition from fibroblast to epithelial morphology. Primary breast cancer fibroblasts BrC4f, being cancer-associated fibroblasts, were subjected to one or two rounds of "pulsed hypoxia" (PH). PH induced transformation of fibroblast-shaped cells to semi-epithelial cells. Western blot analysis, fluorescent microscopy and flow cytometry of transformed cells demonstrated the decrease in the mesenchymal markers vimentin and N-cad and an increase in the epithelial marker E-cad. These cells kept mesenchymal markers αSMA and S100A4 and high ALDH activity. Real-time PCR data of the cells after one (BrC4f_Hyp1) and two (BrC4f_Hyp2) rounds of PH showed consistent up-regulation of TWIST1 gene as an early response and ZEB1/2 and SLUG transcriptional activity as a subsequent response. Reversion of BrC4f_Hyp2 cells to normoxia conditions converted them to epithelial-like cells (BrC4e) with decreased expression of EMT genes and up-regulation of MET-related OVOL2 and c-MYC genes. Transplantation of BrC4f and BrC4f_Hyp2 cells into SCID mice showed the acceleration of tumor growth up to 61.6% for BrC4f_Hyp2 cells. To summarize, rounds of PH imitate the MET process of tumorigenesis in which cancer-associated fibroblasts pass through intermediate stages and become more aggressive epithelial-like tumor cells.

Patient-Derived Primary Cancer-Associated Fibroblasts Mediate Resistance to Anti-Angiogenic Drug in Ovarian Cancers

Ovarian cancers rank first in both aggressiveness and dismal prognosis among gynecological neoplasms. The poor outcome is explained by the fact that most patients present with late-stage disease and progress through the first line of treatment. Ovarian neoplasms, especially epithelial ovarian cancers, are diagnosed at advanced/metastatic stages, often with a high angiogenesis index, one of the hallmarks of ovarian cancers with rapid progression and poor outcome as resistance to anti-angiogenic therapy develops. Despite therapy, the metastatic progression of aggressive ovarian cancer is a spectacularly selective function of tumor cells aided and abetted by the immune, mesenchymal and angiogenic components of the tumor microenvironment (TME) that enforces several pro-metastatic event(s) via direct and indirect interactions with stromal immune cells, cancer-associated fibroblasts (CAFs), and vascular endothelial cells. Since transdifferentiation of tumor endothelium is one of the major sources of CAFs, we hypothesized that ovarian CAF plays a critical role in resisting anti-angiogenic effects via direct crosstalk with endothelium and hence plays a direct role in the development of resistance to anti-angiogenic drugs. To test the hypothesis, we set up a hybrid ex vivo model for co-culture comprising Patient-Derived ex vivo primary CAFs from ovarian tumor samples and human umbilical vein endothelial cells (HUVEC). Patient-Derived CAFs were characterized by the mRNA and protein expression of positive (SMA, S100A4, TE-7, FAP-A, CD90/THY1), negative (EpCAM, CK 8,18, CD31, CD44, CD45), functional (PDGFRA, TGFB1, TGFB2, TGFRA) and immunological markers (PD-L1, PD-L2, PD-1) associated with CAFs by qRT-PCR, flow cytometry, Western blot, and ICC. Data from our HUVEC-on-CAF ex vivo Hybrid Co-Culture (HyCC) study demonstrate the pro-angiogenic effect of Patient-Derived ovarian CAFs by virtue of their ability to resist the effect of anti-angiogenic drugs, thereby aiding the development of resistance to anti-angiogenic drugs. Ascertaining direct experimental proof of the role of CAFs in developing resistance to specific anti-angiogenic drugs will provide an opportunity to investigate new drugs for counteracting CAF resistance and "normalizing/re-educating" TME in aggressive ovarian cancers. Our data provide a unique experimental tool for the personalized testing of anti-angiogenic drugs, positively predicting the development of future resistance to anti-angiogenic drugs well before it is clinically encountered in patients.