GEFT aberrant expression in soft tissue sarcomas

Guanine nucleotide exchange factor T exerts the cancer-promoting function in cholangiocarcinoma by enhancing the Wnt-GSK-3β-β-catenin cascade via regulation of Rac1/Cdc42

Guanine nucleotide exchange factor T (GEFT), which is frequently overexpressed in cancers, is closely related to tumorigenicity and metastasis. Up to now, little is known about the relationship between GEFT and cholangiocarcinoma (CCA). The work explored the expression and function of GEFT in CCA and revealed the underlying mechanisms. Both CCA clinical tissues and cell lines expressed higher levels of GEFT than normal controls. High GEFT levels were correlated with a low overall survival rate in CCA patients. A decrease in GEFT by RNA interference caused remarkable anticancer effects in CCA cells, including retarded proliferation, delayed cell cycle progression, subdued metastatic potential and enhanced chemosensitivity. Mechanistically, GEFT mediated the Wnt-GSK-3β-β-catenin cascade associated with the regulation of Rac1/Cdc42. The inhibition of Rac1/Cdc42 markedly diminished the enhancing effect of GEFT on the Wnt-GSK-3β-β-catenin and reversed GEFT-mediated cancer-promoting effects in CCA. Moreover, the reactivation of β-catenin diminished GEFT-reduction-induced anticancer effects. Critically, CCA cells with decreasing GEFT had a weakened ability to form xenografts in mouse models. Collectively, this work illustrates that GEFT-mediated Wnt-GSK-3β-β-catenin cascade represents a novel mechanism underlying CCA progression and propose a decrease in GEFT as a potential path for treatment in CCA patients.

Radioresistance in rhabdomyosarcomas: Much more than a question of dose

Management of rhabdomyosarcoma (RMS), the most common soft tissue sarcoma in children, frequently accounting the genitourinary tract is complex and requires a multimodal therapy. In particular, as a consequence of the advancement in dose conformity technology, radiation therapy (RT) has now become the standard therapeutic option for patients with RMS. In the clinical practice, dose and timing of RT are adjusted on the basis of patients' risk stratification to reduce late toxicity and side effects on normal tissues. However, despite the substantial improvement in cure rates, local failure and recurrence frequently occur. In this review, we summarize the general principles of the treatment of RMS, focusing on RT, and the main molecular pathways and specific proteins involved into radioresistance in RMS tumors. Specifically, we focused on DNA damage/repair, reactive oxygen species, cancer stem cells, and epigenetic modifications that have been reported in the context of RMS neoplasia in both in vitro and in vivo studies. The precise elucidation of the radioresistance-related molecular mechanisms is of pivotal importance to set up new more effective and tolerable combined therapeutic approaches that can radiosensitize cancer cells to finally ameliorate the overall survival of patients with RMS, especially for the most aggressive subtypes.