Sarcoma Cells Secrete Hypoxia-Modified Collagen VI to Weaken the Lung Endothelial Barrier and Promote Metastasis.

Intratumoral hypoxia correlates with metastasis and poor survival in patients with sarcoma. Using an impedance sensing assay and a zebrafish intravital microinjection model, we demonstrated here that the hypoxia-inducible collagen-modifying enzyme lysyl hydroxylase PLOD2 and its substrate collagen type VI (COLVI) weaken the lung endothelial barrier and promote transendothelial migration. Mechanistically, hypoxia-induced PLOD2 in sarcoma cells modified COLVI, which was then secreted into the vasculature. Upon reaching the apical surface of lung endothelial cells, modified COLVI from tumor cells activated integrin ß1 (ITGß1). Furthermore, activated ITGß1 colocalized with Kindlin2, initiating their interaction with F-actin and prompting its polymerization. Polymerized F-actin disrupted endothelial adherens junctions and induced barrier dysfunction. Consistently, modified and secreted COLVI was required for the late stages of lung metastasis in vivo. Analysis of patient gene expression and survival data from The Cancer Genome Atlas (TCGA) revealed an association between the expression of both PLOD2 and COLVI and patient survival. Furthermore, high levels of COLVI were detected in surgically resected sarcoma metastases from patient lungs and in the blood of tumor-bearing mice. Together, these data identify a mechanism of sarcoma lung metastasis, revealing opportunities for therapeutic intervention. SIGNIFICANCE: Collagen type VI modified by hypoxia-induced PLOD2 is secreted by sarcoma cells and binds to integrin ß1 on endothelial cells to induce barrier dysfunction, which promotes sarcoma vascular dissemination and metastasis.

Oncogene-induced matrix reorganization controls CD8+ T cell function in the soft-tissue sarcoma microenvironment.

CD8+ T cell dysfunction impedes antitumor immunity in solid cancers, but the underlying mechanisms are diverse and poorly understood. Extracellular matrix (ECM) composition has been linked to impaired T cell migration and enhanced tumor progression; however, impacts of individual ECM molecules on T cell function in the tumor microenvironment (TME) are only beginning to be elucidated. Upstream regulators of aberrant ECM deposition and organization in solid tumors are equally ill-defined. Therefore, we investigated how ECM composition modulates CD8+ T cell function in undifferentiated pleomorphic sarcoma (UPS), an immunologically active desmoplastic tumor. Using an autochthonous murine model of UPS and data from multiple human patient cohorts, we discovered a multifaceted mechanism wherein the transcriptional coactivator YAP1 promotes collagen VI (COLVI) deposition in the UPS TME. In turn, COLVI induces CD8+ T cell dysfunction and immune evasion by remodeling fibrillar collagen and inhibiting T cell autophagic flux. Unexpectedly, collagen I (COLI) opposed COLVI in this setting, promoting CD8+ T cell function and acting as a tumor suppressor. Thus, CD8+ T cell responses in sarcoma depend on oncogene-mediated ECM composition and remodeling.

The Role of Gasdermin-D-Mediated Pyroptosis in Organ Injury and Its Therapeutic Implications.

Gasdermin-D (GSDMD) belongs to the Gasdermin family (GSDM), which are pore-forming effector proteins that facilitate inflammatory cell death, also known as pyroptosis. This type of programmed cell death is dependent on inflammatory caspase activation, which cleaves gasdermin-D (GSDMD) to form membrane pores and initiates the release of pro-inflammatory cytokines. Pyroptosis plays an important role in achieving immune regulation and homeostasis within various organ systems. The role of GSDMD in pyroptosis has been extensively studied in recent years. In this review, we summarize the role of GSDMD in cellular and organ injury mediated by pyroptosis. We will also provide an outlook on GSDMD therapeutic targets in various organ systems.

TGFß and Hippo Pathways Cooperate to Enhance Sarcomagenesis and Metastasis through the Hyaluronan-Mediated Motility Receptor (HMMR).

High-grade sarcomas are metastatic and pose a serious threat to patient survival. Undifferentiated pleomorphic sarcoma (UPS) is a particularly dangerous and relatively common sarcoma subtype diagnosed in adults. UPS contains large quantities of extracellular matrix (ECM) including hyaluronic acid (HA), which is linked to metastatic potential. Consistent with these observations, expression of the HA receptor, hyaluronan-mediated motility receptor (HMMR/RHAMM), is tightly controlled in normal tissues and upregulated in UPS. Moreover, HMMR expression correlates with poor clinical outcome in these patients. Deregulation of the tumor-suppressive Hippo pathway is also linked to poor outcome in these patients. YAP1, the transcriptional regulator and central effector of Hippo pathway, is aberrantly stabilized in UPS and was recently shown to control RHAMM expression in breast cancer cells. Interestingly, both YAP1 and RHAMM are linked to TGFß signaling. Therefore, we investigated crosstalk between YAP1 and TGFß resulting in enhanced RHAMM-mediated cell migration and invasion. We observed that HMMR expression is under the control of both YAP1 and TGFß and can be effectively targeted with small-molecule approaches that inhibit these pathways. Furthermore, we found that RHAMM expression promotes tumor cell proliferation and migration/invasion. To test these observations in a robust and quantifiable in vivo system, we developed a zebrafish xenograft assay of metastasis, which is complimentary to our murine studies. Importantly, pharmacologic inhibition of the TGFß-YAP1-RHAMM axis prevents vascular migration of tumor cells to distant sites. IMPLICATIONS: These studies reveal key metastatic signaling mechanisms and highlight potential approaches to prevent metastatic dissemination in UPS.YAP1 and TGFß cooperatively enhance proliferation and migration/invasion of UPS and fibrosarcomas.