Roles of Hippo-YAP/TAZ signalling in intervertebral disc degeneration

Honokiol regulates ovarian cancer cell malignant behavior through YAP/TAZ pathway modulation

BACKGROUND

Ovarian cancer (OVCA) stands as one of the most fatal gynecological malignancies. Honokiol (HNK) has been substantiated by numerous studies for its anti-tumor activity against malignancies including OVCA. Consequently, this work was designed to elucidate the impact of HNK-mediated modulation of the YAP/TAZ pathway on the biological functions of OVCA cells.

METHODS

OVCA cells were subjected to treatment with varying concentrations (0, 25, 50, 75, and 100 μM) of HNK, concomitant with the administration of YAP agonist (XMU). Assessment of cellular viability was executed employing the CCK-8 assay, while quantification of cellular proliferation transpired via colony formation assays. Apoptosis was ascertained using flow cytometry, and expression of apoptosis-related proteins (caspase-3, Bcl-2, Bax), EMT-related proteins (E-cadherin, N-cadherin), migration-associated proteins (MMP-2, MMP-9), and YAP/TAZ pathway-related proteins was evaluated by western blot. Transwell experiments were conducted to assess cellular migratory and invasive propensities. Xenograft tumor models were built to observe tumor growth (volume and weight), apoptosis was assessed by TUNEL staining, and Ki67 expression was evaluated through IHC.

RESULTS

HNK exerted inhibitory effects on the viability and proliferative capacity of OVCA cells, elicited apoptotic responses, curtailed the migratory and invasive tendencies of cells, and downregulated the YAP/TAZ pathway. Stimulation with YAP agonist (XMU-MP-1) partially attenuated the impacts of HNK on OVCA cell biology. Experiments in vivo confirmed that HNK inhibited OVCA tumor growth.

CONCLUSION

The outcomes of this investigation conclusively established that HNK orchestrated the modulation of the YAP/TAZ pathway, thereby exerting control over the malignant phenotypic manifestations of OVCA cells. The ascertained function of HNK in restraining cellular proliferation and tumor progression provided novel evidence of its anti-proliferative activity within OVCA cells.

SEPHS1 attenuates intervertebral disc degeneration by delaying nucleus pulposus cell senescence through the Hippo-Yap/Taz pathway

Nucleus pulposus cell (NPC) senescence is a major cause of intervertebral disc degeneration (IVDD). Oxidative stress and reactive oxygen species (ROS) play critical roles in regulating cell senescence. Selenophosphate synthetase 1 (SEPHS1) was reported to play an important role in mitigating oxidative stress in an osteoarthritis (OA) model by reducing the production of ROS, thereby, delaying the occurrence and development of osteoarthritis. In this study, we explored the, hitherto unknown, role of SEPHS1 in IVDD in vitro and in vivo using an interleukin-1β (IL-1β)-induced NPC senescence model and a rat needle puncture IVDD model, respectively. SEPHS1 delayed NPC senescence in vitro by reducing ROS production. Age-related dysfunction was also ameliorated by the overexpression of SEPHS1 and inhibition of the Hippo-Yap/Taz signaling pathway. In vivo experiments revealed that the overexpression of SEPHS1 and inhibition of Hippo-Yap/Taz alleviated IVDD in rats. Moreover, a selenium (Se)-deficient diet and lack of SEPHS1 synergistically aggravated IVDD progression. Taken together, our results demonstrate that SEPHS1 plays a significant role in NPC senescence. Overexpression of SEPHS1 and inhibition of Hippo-Yap/Taz can delay NPC senescence, restore the balance of extracellular matrix metabolism, and attenuate IVDD. SEPHS1 could be a promising therapeutic target for IVDD.NEW & NOTEWORTHY Selenophosphate synthetase 1 (SEPHS1) deficiency leads to an increase in reactive oxygen species levels and in the subsequent activation of the Hippo-Yap/Taz signaling pathway. In the rat model of intervertebral disc degeneration (IVDD), overexpression of SEPHS1 and inhibition of Hippo-YAP/Taz mitigated the progression of disc degeneration indicating the involvement of SEPHS1 in IVDD. SEPHS1 is a promising therapeutic target for IVDD.