Increasing the efficiency of hyperthermic intraperitoneal chemotherapy (HIPEC) by combination with a photosensitive drug in pediatric rhabdomyosarcoma in an animal model.

BACKGROUND: Cytoreductive surgery (CRS) in combination with hyperthermic intraperitoneal chemotherapy (HIPEC) is an option in advanced peritoneal sarcomatosis. Nevertheless, CRS and HIPEC are not successful in all patients. An enhancement of HIPEC using photodynamic therapy (PDT) might be beneficial. Therefore, a combination of the photosensitizer hypericin (HYP) with HIPEC was evaluated in an animal model. PROCEDURE: An established HIPEC animal model for rhabdomyosarcoma (NOD/LtSz-scid IL2Rγnullmice, n = 80) was used. All groups received HYP (100 µg/200 µl) intraperitoneally with and without cisplatin-based (30 or 60 mg/m2 ) HIPEC (37°C or 42°C, for 60 minutes) (five groups, each n = 16). Peritoneal cancer index (PCI) was documented visually and by HYP-based photodynamic diagnosis (PDD). HYP-based PDT of the tumor was performed. Tissue samples were evaluated regarding proliferation (Ki-67) and apoptosis (TUNEL). RESULTS: HYP uptake was detected even in smallest tumor nodes (<1 mm) with improved tumor detection during PDD (PCI with PDD vs. PCI without PDD: 8.5 vs. 7, p < .001***). Apoptotic effects after PDT without HIPEC were limited to the tumor surface, whereas PDT after HIPEC (60 mg/m2 , 42°C) showed additional reduction of tumor proliferation in the top nine to 11 cell layers (50 µm). CONCLUSION: HYP as fluorescent photosensitizer offers an intraoperative diagnostic advantage detecting intraperitoneal tumor dissemination. The combination of HYP and cisplatin-based HIPEC was feasible in vivo, showing enhanced effects on tumor proliferation and apoptosis induction across the tumor surface. Further studies combining HYP and HIPEC will follow to establish a clinical application.

Investigating nucleo-cytoplasmic shuttling of the human DEAD-box helicase DDX3.

The human DEAD-box helicase DDX3 is a multi-functional protein involved in the regulation of gene expression and additional non-conventional roles as signalling adaptor molecule that are independent of its enzymatic RNA remodeling activity. It is a nucleo-cytoplasmic shuttling protein and it has previously been suggested that dysregulation of its subcellular localization could contribute to tumourigenesis. Indeed, both tumour suppressor and oncogenic functions have been attributed to DDX3. In this study, we investigated the regulation of DDX3's nucleocytoplasmic shuttling. We confirmed that an N-terminal conserved Nuclear Export Signal (NES) is required for export of human DDX3 from the nucleus, and identified three regions within DDX3 that can independently facilitate its nuclear import. We also aimed to identify conditions that alter DDX3's subcellular localisation. Viral infection, cytokine treatment and DNA damage only induced minor changes in DDX3's subcellular distribution as determined by High Content Analysis. However, DDX3's nuclear localization increased in early mitotic cells (during prophase) concomitant with an increase in DDX3 expression levels. Our results are likely to have implications for the proposed use of (nuclear) DDX3 as a prognostic biomarker in cancer.