ABSTRACT
Metastatic castration resistant prostate cancer (mCRPC) relapse due to acquired resistance to chemotherapy, such as docetaxel, remains a major threat to patient survival. Resistance of mCRPC to docetaxel can be associated with elevated levels of soluble clusterin (sCLU) and growth differentiation factor15 (GDF15). Any strategies aiming to modulate sCLU and/or GDF15 in docetaxelresistant prostate cancer cells present a therapeutic interest. The present study reports the cytotoxic effect of a nitric oxide donor, glyceryl trinitrate (GTN), on docetaxelresistant mCRPC human cell lines and demonstrates that GTN displays greater inhibition of cell viability toward docetaxelresistant mCRPC cells than on mCRPC cells. It is also demonstrated that GTN modulates the level of expression of clusterin (CLU) which is dependent of GDF15, two markers associated with docetaxel resistance in prostate cancer. The results indicate that GTN represses the level of expression of the cytoprotective isoform of CLU (sCLU) and can increase the level of expression of the cytotoxic isoform (nuclear CLU) in docetaxel resistant cells. Furthermore, it was observed that GTN differentially regulates the level of the precursor form of GDF15 between resistant and parental cells, and that recombinant GDF15 can modulate the expression of CLU isoforms and counteract GTNinduced cytotoxicity in resistant cells. A link was established between GDF15 and the expression of CLU isoforms. The present study thus revealed GTN as a potential therapeutic strategy to overcome docetaxelresistant mCRPC.
Subject(s)
Clusterin/metabolism , Docetaxel/pharmacology , Drug Resistance, Neoplasm/drug effects , Nitroglycerin/administration & dosage , Prostatic Neoplasms, Castration-Resistant/drug therapy , Animals , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Clusterin/genetics , Gene Expression Regulation, Neoplastic/drug effects , Growth Differentiation Factor 15/genetics , Growth Differentiation Factor 15/metabolism , Humans , Male , Nitroglycerin/pharmacology , Prostatic Neoplasms, Castration-Resistant/genetics , Prostatic Neoplasms, Castration-Resistant/metabolism , Xenograft Model Antitumor Assays , ZebrafishABSTRACT
Collapsin response mediator protein 5 (CRMP5) belongs to a family of five cytosolic proteins that play a major role in nervous system development. This protein was first described in cancer-induced autoimmune processes, causing neurodegenerative disorders (paraneoplastic neurologic syndromes). CRMP5 expression has been reported to serve as a biomarker for high-grade lung neuroendocrine carcinomas; however, its functional roles have not been examined in any setting of cancer pathophysiology. In this study, we report two different CRMP5 expression patterns observed in human glioblastoma (GBM) biopsies that establish connections between CRMP5 expression, Notch receptor signaling, and GBM cell proliferation. We demonstrated that elevated CRMP5 promotes Notch receptor expression and Akt activation in human tumor cell lines, GBM stem cells, and primary tumor biopsies. We have shown that the high CRMP5 and Notch expression in GBM xenograft is related to stem cells. This suggests that high CRMP5 expression pattern in GBM biopsies encompasses a subset of stem cells. Mechanistically, CRMP5 functioned by hijacking Notch receptors from Itch-dependent lysosomal degradation. Our findings suggest that CRMP5 serves as a major mediator of Notch signaling and Akt activation by controlling the degradation of the Notch receptor, with implications for defining a biomarker signature in GBM that correlates with and may predict patient survival.
Subject(s)
Brain Neoplasms/genetics , Glioblastoma/genetics , Nerve Tissue Proteins/biosynthesis , Receptors, Notch/genetics , Adult , Aged , Aged, 80 and over , Animals , Brain Neoplasms/pathology , Cell Line, Tumor , Cell Proliferation/genetics , Female , Gene Expression Regulation, Neoplastic , Glioblastoma/pathology , Humans , Hydrolases , Male , Mice , Microtubule-Associated Proteins , Middle Aged , Nerve Tissue Proteins/genetics , Receptors, Notch/metabolism , Signal Transduction , Survival Analysis , Xenograft Model Antitumor AssaysABSTRACT
To investigate the effect of nitric oxide on tumor development, we established a rat tumor xenograft model in zebrafish embryos. The injected tumor cells formed masses in which nitric oxide production could be detected by the use of the cell-permeant DAF-FM-DA (diaminofluorophore 4-amino-5-methylamino-2'-7'-difluorofluorescein diacetate) and DAR-4M-AM (diaminorhodamine-4M). This method revealed that nitric oxide production could be co-localized with the tumor xenograft in 46% of the embryos. In 85% of these embryos, tumors were vascularized and blood vessels were observed on day 4 post injection. Furthermore, we demonstrated by qRT-PCR that the transplanted glioma cells highly expressed Nos2, Vegfa and Cyclin D1 mRNA. In the xenografted embryos we also found increased zebrafish vegfa expression. Glioma and zebrafish derived Vegfa and tumor Cyclin D1 expression could be down regulated by the nitric oxide scavenger 2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide or CPTIO. We conclude that even if there is a heterogeneous nitric oxide production by the xenografted glioma cells that impacts Vegfa and Cyclin D1 expression levels, our results suggest that reduction of nitric oxide levels by nitric oxide scavenging could be an efficient approach to treat glioma.
