No abstract

Oncogene-evoked replication stress (RS) fuels genomic instability in diverse cancer types. Here we report that BRCA1, traditionally regarded a tumour suppressor, plays an unexpected tumour-promoting role in glioblastoma (GBM), safeguarding a protective response to supraphysiological RS levels. Higher BRCA1 positivity is associated with shorter survival of glioma patients and the abrogation of BRCA1 function in GBM enhances RS, DNA damage (DD) accumulation and impairs tumour growth. Mechanistically, we identify a novel role of BRCA1 as a transcriptional co-activator of RRM2 (catalytic subunit of ribonucleotide reductase), whereby BRCA1-mediated RRM2 expression protects GBM cells from endogenous RS, DD and apoptosis. Notably, we show that treatment with a RRM2 inhibitor triapine reproduces the BRCA1-depletion GBM-repressive phenotypes and sensitizes GBM cells to PARP inhibition. We propose that GBM cells are addicted to the RS-protective role of the BRCA1-RRM2 axis, targeting of which may represent a novel paradigm for therapeutic intervention in GBM.

Glioblastomas are deadly neoplasms resistant to current treatment modalities. Fibroblast activation protein (FAP) is a protease which is not expressed in most of the normal adult tissues but is characteristically present in the stroma of extracranial malignancies. FAP is considered a potential therapeutic target and is associated with a worse patient outcome in some cancers. The FAP localization in the glioma microenvironment and its relation to patient survival are unknown. By analyzing 56 gliomas and 15 non-tumorous brain samples, we demonstrate increased FAP expression in a subgroup of high-grade gliomas, in particular on the protein level. FAP expression was most elevated in the mesenchymal subtype of glioblastoma. It was neither associated with glioblastoma patient survival in our patient cohort nor in publicly available datasets. FAP was expressed in both transformed and stromal cells; the latter were frequently localized around dysplastic blood vessels and commonly expressed mesenchymal markers. In a mouse xenotransplantation model, FAP was expressed in glioma cells in a subgroup of tumors that typically did not express the astrocytic marker GFAP. Endogenous FAP was frequently upregulated and part of the FAP host cells coexpressed the CXCR4 chemokine receptor. In summary, FAP is expressed by several constituents of the glioblastoma microenvironment, including stromal non-malignant mesenchymal cells recruited to and/or activated in response to glioma growth. The limited expression of FAP in healthy tissues together with its presence in both transformed and stromal cells suggests that FAP may be a candidate target for specific delivery of therapeutic agents in glioblastoma.

Cercariae of the nasal bird schistosome Trichobilharzia regenti are able to penetrate into mammalian skin and migrate to the mouse central nervous system (CNS) causing tissue injury in certain cases. Our study shows that the severity of T. regenti pathologies in the CNS closely depends on the host immune status. During the primary infection of immunocompetent mice, the parasites evoked an acute inflammatory reaction in the skin and the CNS involving focal oedema and cellular infiltration of the tissue. Challenge infections resulted in the development of extensive inflammatory foci in the host skin which precluded the subsequent migration of the schistosomula to the CNS. On the other hand, during primary as well as challenge infections of immunodeficient mice (SCID), no significant immune response against the parasites was detected in any of the host organs examined; however, in contrast to immunocompetent mice, the infections were frequently manifested by severe leg paralysis.

Glioblastoma multiforme (GBM) is the most common and malignant primary intracranial tumor, and has a median survival of only 10 to 14 months with only 3 to 5% of patients surviving more than three years. Recurrence (RGBM) is nearly universal, and further decreases the median survival to only five to seven months with optimal therapy. Tumor-treating fields (TTField) therapy is a novel treatment technique that has recently received CE and FDA approval for the treatment of RGBM, and is based on the principle that low intensity, intermediate frequency electric fields (100 to 300 kHz) may induce apoptosis in specific cell types. Our center was the first to apply TTField treatment to histologically proven GBM in a small pilot study of 20 individuals in 2004 and 2005, and four of those original 20 patients are still alive today. We report two cases of GBM and two cases of RGBM treated by TTField therapy, all in good health and no longer receiving any treatment more than seven years after initiating TTField therapy, with no clinical or radiological evidence of recurrence.