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Glioblastomas (GBM) are brain tumors with a poor prognosis despite treatment that combines surgical resection and radio-chemotherapy. These tumors are characterized by abundant vascularization and significant cellular heterogeneity including GBM stem-like cells (GSC) which contribute to tumor aggressiveness, resistance, and recurrence. Recent data has demonstrated that GSC are directly involved in the formation of new vessels via their transdifferentiation into Tumor Derived Endothelial Cells (TDEC). We postulate that cellular stress such as ionizing radiation (IR) could enhance the transdifferentiation of GSC into TDEC. GSC neurospheres isolated from 3 different patients were irradiated or not and were then transdifferentiated into TDEC. In fact, TDEC obtained from irradiated GSC (TDEC IR + ) migrate more towards VEGF, form more pseudotubes in MatrigelTM in vitro and develop more functional blood vessels in MatrigelTM plugs implanted in Nude mice than TDEC obtained from non-irradiated GSC. Transcriptomic analysis allows us to highlight an overexpression of Tie2 in TDEC IR+. All IR-induced effects on TDEC were abolished by using a Tie2 kinase inhibitor, which confirms the role of the Tie2 signaling pathway in this process. Finally, by analyzing Tie2 expression in patient GBMs by immunohistochemistry, we demonstrated that the number of Tie2+ vessels increases in recurrent GBM compared with matched untreated tumors. In conclusion, we demonstrate that IR potentiates proangiogenic features of TDEC through the Tie2 signaling pathway, which indicates a new pathway of treatment-induced tumor adaptation. New therapeutic strategies that associate standard treatment and a Tie2 signaling pathway inhibitor should be considered for future trials.

Based on epidemiological, clinical, and preclinical data, lung carcinogenesis can be distinctive in women, suggesting that women should be treated differently depending on the expression of various specific biomarkers. We aimed to describe the hormonal and genetic profile of lung cancer in both men and women to identify gender specificities. Primary lung-tumor tissues from surgically treated patients, (50 men, 50 women) were analyzed and compared for expression of estrogen receptors (ER) α and β, progesterone receptors (PR), epidermal growth-factor receptor (EGFR), and HER2 (for EGFR and K-Ras mutations). These data were combined with clinical and outcome data. Fewer women with lung cancer were smokers (p=0.001) and they smoked fewer cigarettes (p=0.001). We observed a higher rate of EGFR mutations (p=0.02) and ERα expression (p=0.006) in women. ERβ and EGFR were also expressed more frequently in women (p=0.29 and p=0.16). HER2 was overexpressed regardless of gender in three men and two women. K-Ras was mutated in 16% of both men and women. Interestingly, there was a positive link between EGFR expression and expression of ERα (p=0.028) and ERβ (p=0.047) in both men and women. Expression of ERα was associated with improved disease-free survival (p=0.007). Our findings provide further evidence on the specificities of lung cancer in women. The differential expression of specific biomarkers, which could be targeted by therapy, favors the development of gender-based treatment guided by biomarker expression.