PER2 Circadian Oscillation Sensitizes Esophageal Cancer Cells to Chemotherapy

Simple Summary

There are growing evidences that the circadian rhythm modulates key cellular processes in physiological and pathological conditions. Here, we characterized the consequences of the daily oscillations of the clock-related gene PER2 in esophageal cancer cells and found that chemotherapy is more efficient when PER2 expression is low. These results suggest that chronotherapy might be used to potentiate the impact of current chemotherapy regimen.

Abstract

Esophageal squamous cell carcinoma (eSCC) accounts for more than 85% cases of esophageal cancer worldwide and the 5-year survival rate associated with metastatic eSCC is poor. This low survival rate is the consequence of a complex mechanism of resistance to therapy and tumor relapse. To effectively reduce the mortality rate of this disease, we need to better understand the molecular mechanisms underlying the development of resistance to therapy and translate that knowledge into novel approaches for cancer treatment. The circadian clock orchestrates several physiological processes through the establishment and synchronization of circadian rhythms. Since cancer cells need to fuel rapid proliferation and increased metabolic demands, the escape from circadian rhythm is relevant in tumorigenesis. Although clock related genes may be globally repressed in human eSCC samples, PER2 expression still oscillates in some human eSCC cell lines. However, the consequences of this circadian rhythm are still unclear. In the present study, we confirm that PER2 oscillations still occur in human cancer cells in vitro in spite of a deregulated circadian clock gene expression. Profiling of eSCC cells by RNAseq reveals that when PER2 expression is low, several transcripts related to apoptosis are upregulated. Consistently, treating eSCC cells with cisplatin when PER2 expression is low enhances DNA damage and leads to a higher apoptosis rate. Interestingly, this process is conserved in a mouse model of chemically-induced eSCC ex vivo. These results therefore suggest that response to therapy might be enhanced in esophageal cancers using chronotherapy.

SCO-spondin oligopeptide inhibits angiogenesis in glioblastoma

Angiogenesis plays a critical role in glioblastoma growth and progression. We therefore aimed at evaluating the anti-angiogenic properties of an oligopeptide originating from SCO-spondin (NX) on a model of human glioblastoma. To this end, we studied the impact of NX treatment on human brain endothelial cells (HBMECs) alone or co-cultured with glioblastoma cells (U87-MG) on apoptosis, proliferation, migration and release of angiogenic factors. We further investigated the anti-angiogenic potential of NX on human glioblastoma cells grown on chorio-allantoic membrane (CAM) or in glioblastoma xenografts. The results of our experiments showed that NX treatment impaired the microvascular network and induced a decrease in cell proliferation, vascularization and tumor growth in the CAM model as well as in xenotransplants. Interestingly, our in vitro experiments showed that NX impairs HBMECs migration but also regulates the release of angiogenic factors from U87-MG. These results are confirmed by the profiling of NX-treated U87-MG grown on CAM that highlighted modifications of several genes involved in angiogenesis. In conclusion, NX inhibits tumorigenesis by impairing the ability of glioblastoma cells to induce angiogenesis and by inhibiting endothelial cell migration. This molecule might therefore be an interesting candidate for future cancer therapies.

New ex-ovo colorectal-cancer models from different SdFFF-sorted tumor-initiating cells

Despite effective treatments, relapse of colorectal cancer (CRC) is frequent, in part caused by the existence of tumor-initiating cells (TICs). Different subtypes of TICs, quiescent and activated, coexist in tumors, defining the tumor aggressiveness and therapeutic response. These subtypes have been sorted by hyperlayer sedimentation field-flow fractionation (SdFFF) from WiDr and HCT116 cell lines. On the basis of a new strategy, including TIC SdFFF sorting, 3D Matrigel amplification, and grafting of corresponding TIC colonies on the chick chorioallantoic membrane (CAM), specific tumor matrices could be obtained. If tumors had similar architectural structure with vascularization by the host system, they had different proliferative indices in agreement with their initial quiescent or activated state. Protein analysis also revealed that tumors obtained from a population enriched for "activated" TICs lost "stemness" properties and became invasive. In contrast, tumors obtained from a population enriched for "quiescent" TICs kept their stemness properties and seemed to be less proliferative and invasive. Then, it was possible to produce different kinds of tumor which could be used as selective supports to study carcinogenesis and therapy sensitivity.