Connolly, Nina P.

Abstract Background Fibroblast growth factor-inducible 14 (Fn14) belongs to the TNFR superfamily. Fn14 overexpression can drive receptor-autonomous signaling, increase both cell invasion and tumor-associated macrophages/microglia (TAMMs) recruitment, and correlates with reduced survival in glioblastoma (GBM) patients and rat gliomas. While prior studies report Fn14 expression in non-tumor cells within the GBM tumor microenvironment (TME), their relative contributions to glioma pathobiology remain unclear. Methods Using tumor-host pairings of Fn14-positive and -knockout (-KO) cells and mice, we examined the role of Fn14 in glioma biology. Mouse glioma and human GBM datasets were analyzed at the cellular, protein, and transcriptomic levels to assess Fn14-associated changes in the glioma TME and survival outcomes. Results Fn14 was found to be highly expressed in tumor cells and TAMMs in human GBM and 2 well-characterized murine glioma models. Fn14 KO in both tumor and host cells increased overall survival. Notably, this survival benefit was greater in the glioma model characterized by a more immunologically activated TME. Immunophenotyping revealed that Fn14 loss reshapes the tumor-immune landscape, reducing the presence of immunosuppressive macrophages and exhausted T-cells, suggesting that Fn14 modulates both innate and adaptive immune responses. These findings were supported by analyses of human GBM datasets, where high Fn14 expression correlated with immunosuppressive shifts and poor patient responses to immune checkpoint inhibitor therapy. Conclusions This study provides the first description of the contributions of both tumor- and host-derived Fn14 expression to tumor immunity and survival and identifies Fn14 as an important mediator of innate and adaptive immune responses in gliomas.

AbstractHigh‐grade gliomas (HGGs) are aggressive, treatment‐resistant, and often fatal human brain cancers. The TNF‐like weak inducer of apoptosis (TWEAK)/fibroblast growth factor‐inducible 14 (Fn14) signaling axis is involved in tissue repair after injury and constitutive signaling has been implicated in the pathogenesis of numerous solid cancers. The Fn14 gene is expressed at low levels in the normal, uninjured brain but is highly expressed in primary isocitrate dehydrogenase wild‐type and recurrent HGGs. Fn14 signaling is implicated in numerous aspects of glioma biology including brain invasion and chemotherapy resistance, but whether Fn14 overexpression can directly promote tumor malignancy has not been reported. Here, we used the replication‐competent avian sarcoma‐leukosis virus/tumor virus A system to examine the impact of Fn14 expression on glioma development and pathobiology. We found that the sole addition of Fn14 to an established oncogenic cocktail previously shown to generate proneural‐like gliomas led to the development of highly invasive and lethal brain cancer with striking biological features including extensive pseudopalisading necrosis, constitutive canonical and noncanonical NF‐κB pathway signaling, and high plasminogen activator inhibitor‐1 (PAI‐1) expression. Analyses of HGG patient datasets revealed that high human PAI‐1 gene (SERPINE1) expression correlates with shorter patient survival, and that the SERPINE1 and Fn14 (TNFRSF12A) genes are frequently co‐expressed in bulk tumor tissues, in tumor subregions, and in malignant cells residing in the tumor microenvironment. These findings provide new insights into the potential importance of Fn14 in human HGG pathobiology and designate both the NF‐κB signaling node and PAI‐1 as potential targets for therapeutic intervention.Main PointsThis work demonstrates that elevated levels of the TWEAK receptor Fn14 in tumor‐initiating, neural progenitor cells leads to the transformation of proneural‐like gliomas into more aggressive and lethal tumors that exhibit constitutive NF‐κB pathway activation and plasminogen activator inhibitor‐1 overexpression.

DART nanoparticles overcome critical drug delivery barriers for primary tumors and brain metastases.

Abstract Fibroblast growth factor-inducible 14 (Fn14) is the cell surface receptor for the tumor necrosis factor (TNF) family member TNF-like weak inducer of apoptosis (TWEAK). The Fn14 gene is not normally expressed in healthy tissues, but expression is significantly increased in many primary solid tumor types, including glioblastoma (GBM). High Fn14 expression in tumors is often associated with the stimulation of cancer cell invasion leading to diffuse, aggressive tumors and metastasis. To investigate the effects of increased Fn14 expression in brain tumors, two different tumor types were developed using the RCAS/tv-a transgenic rat model: a low-Fn14, “proneural-like” (PDGFA/shP53 derived) tumor and a high-Fn14 (PDGFA/shP53/Fn14-derived) tumor. Interestingly, rats with high-Fn14 brain tumors had a significantly shorter median survival compared to those with low-Fn14 with 42 days and 70 days median survival, respectively. Using MR proton spectroscopy, both tumor types exhibited the markers of a malignant glioma such as increases in choline to creatinine ratio (Cho/Cr) and decreases in neuronal activity (NAA); however, high-Fn14 tumors also displayed an increase in lactate during tumor progression which is often a sign of high grade, necrotic tumors and poor prognosis. Morphologically, the two tumor subtypes appear quite different. H&E staining of the high-Fn14 tumors showed a highly malignant tumor with several areas of pseudopalisading necrosis within the tumor core. This is different than the somewhat more homogeneous morphology of the low-Fn14 proneural-like tumor. The pattern of tumor cell invasion also differs between the two brain cancer subtypes. High-Fn14 tumors show a more human GBM-like pattern by invading along the white matter tracts whereas low-Fn14 tumors appear to invade more locally with minimal white matter invasion. High-Fn14 tumors were positive for Fn14 throughout the tumor including the invasive rim of the tumor, which is also seen in human GBM, whereas the low-Fn14 tumor revealed very little staining even at the invasive rim. These findings indicate that increased Fn14 expression creates a more malignant brain tumors that develops and behaves more aggressively then low-Fn14 tumors. Citation Format: Nina Connolly, Heather Ames, Nhan L. Tran, Anthony Kim, Jeff Winkles, Graeme Woodworth. Fn14 overexpression in RCAS/tv-a rat gliomas promotes tumor progression, increases invasion and decreases survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3701.