Disrupting Paraspeckle Stability by Targeting WTX-NONO Phase Separation Enhances Chemotherapy Efficacy in Gastric Cancer

Nuclear paraspeckles play critical roles in orchestrating gene transcription to support tumor development and progression. Elucidating regulators of their dynamic compositions and formation could provide potential targets for treating cancer. In this study, we discovered that the short isoform of Wilms tumor gene on the X chromosome (WTX-S) specifically disrupted paraspeckle stability. WTX-S selectively interacted with and sequestered NONO (also as p54nrb) from paraspeckles. Mechanistically, interaction between WTX-S and NONO induced formation of nuclear bodies via liquid-liquid phase separation (WTX-NB). The coiled-coil domain 2 directly interacted with NONO-coiled-coil domain to compartmentalize paraspeckle proteins and subsequently disrupt paraspeckle stability. Functionally, the paraspeckle disintegration induced by WTX-NBs resulted in enhanced chemotherapy sensitivity and favorable prognosis in gastric cancer. Importantly, the cell-penetrating synthetic peptide WTXAP, based on the WTX-NONO interface, mimicked WTX-NB-mediated paraspeckle disintegration and exhibited potent antitumor activity. Likewise, treatment with KPT-330, an FDA-approved XPO1 inhibitor, significantly increased the extent of WTX-S-mediated paraspeckle disintegration, sensitizing WTXhigh gastric cancer to chemotherapy. Collectively, these findings characterize the function and potential clinical significance of WTX-NBs, offering a strategy for sensitizing gastric cancer to chemotherapy.Significance: WTX binding to NONO regulates the balance of biomolecular condensates, providing an axis that can be harnessed to perturb paraspeckles and improve chemotherapy sensitivity in gastric cancer.