XAV939 promotes apoptosis in a neuroblastoma cell line via telomere shortening

Abstract

Abstract. Telomeres, telomerase and tankyrase (TNKS) have an extremely important and special association with human cell aging and cancer. Telomerase activity is abnormally high in cancer cells and is accompanied by the overexpression of tankyrase 1 (TNKS1). TNKS1 is a positive regulator of telomerase activation and telomere extension in the human body, indicating that TNKS1 may be a possible therapeutic target for cancer. XAV939 is a small-molecule inhibitor of TNKS1. The objective of the present study was to investigate the apoptotic effect of XAV939 on the neuroblastoma (NB) SH-SY5Y cell line, as well as the change in telomere length and telomerase activity and elucidate the mechanism from this perspective. In the present study, we initially treated SH-SY5Y cells with XAV939 and RNA interference (RNAi)-TNKS1, and subsequently chose the optimal sequence for RNAi-TNKS1. We then measured the telomere length using quantitative real-time polymerase chain reaction (qPCR) assay, detected the telomerase activity using the ELISA kit, observed apoptotic morphology by transmission electron microscopy, and detected the percentages of apoptotic cells using flow cytometry and Hoechst 33342 staining. We also determined the invasive ability by a cell invasion assay. The results showed that short hairpin RNA-2 (shRNA-2) was the optimal sequence for RNAi-TNKS1. Treatment with both XAV939 and RNAi-TNKS1 shortened the telomere length, promoted apoptosis and reduced the invasive ability of the SH-SY5Y cells, yet had no effect on telomerase activity. XAV939 promoted apoptosis and reduced the invasiveness of SH-SY5Y cells dependent on telomere shortening, and further research should be conducted to clarify the exact mechanisms. This research may contribute to the cure of malignant NB using multi-targeted therapy with small-molecule agents. IntroductionTelomeres, telomerase and tankyrase (TNKS) have an extremely important and special association with human 'cell aging' and 'immortalized cells', offering new opportunities for the research of senescence and cancer. Telomere is a short DNA-protein complex that presents in the linear chromosome ends of eukaryotic cells and constitutes a special hat-like structure along with telomere-binding proteins to maintain the integrity of chromosomes. Telomerase is a ribonucleoprotein complex of RNA and protein composition, and belongs to the reverse transcriptases. Subunits of the human telomerase gene include telomerase RNA (hTR), telomerase binding protein (hTP1) and telomerase activity catalytic unit (hTERT). The main function of telomerase is to maintain telomere length. Telomeres can use the 3' end as primers, their own RNA as a template to synthesize telomere repeat sequences of TTAGGG, and add these to chromosome ends to maintain the original length of the telomere. Telomerase activity has been found in germ and stem cells, which have self-renewal capacity, and in 80-95% of tumors, yet it is weak or has no activity in normal somatic cells (1). Telomerase activity gradually disappears with ...

Disruption of Wnt/β-Catenin Signaling and Telomeric Shortening Are Inextricable Consequences of Tankyrase Inhibition in Human Cells

“…Our data are consistent with Tnks inhibitorinduced telomeric shortening independent of changes to the Wnt signaling status in this cell line. We note that another study using XAV-939 observed similar effects on telomere length maintenance in a neuroblastoma cell line, thereby extending the relevance of our findings to other cell types (35). Taken together, our findings reveal a single-agent strategy for inducing telomerase shortening that is distinct from current efforts devoted to directly targeting telomerase.…”

Novel therapeutic strategies targeting telomere maintenance mechanisms in high-risk neuroblastoma

“…XAV939 is an inhibitor of tankyrase, a positive regulator or telomerase. It has been shown to induce apoptosis in the telomerase expressing neuroblastoma cell line SH-SY5Y [70].…”

WNT Signaling in Neuroblastoma

“…Also, tankyrase 1/2 inhibitors such as XAV935 and XAV939 may have promising effects in progressed and chemoresistant relapsed NB. They were reported to increase apoptosis by the induction of telomere shortening, prevent chemoresistance and inhibit WNT-β-catenin signaling, even in MYCN-amplified tumors [70,71,104,105]. However, NB is a tumor of children and most cases occur in young children.…”