14-3-3ζ targeting induced senescence in Hep-2 laryngeal cancer cell through deneddylation of Cullin1 in the Skp1-Cullin-F-box protein complex

Objectives

Despite of the aberrant expression of 14‐3‐3ζ in head and neck squamous cell carcinoma (HNSCC), little is known about the role of 14‐3‐3ζ in the regulation of senescence in HNSCC. This study was performed to investigate whether 14‐3‐3ζ is implicated in senescence evasion of Hep‐2 laryngeal cancer cells.

Methods

The expression of 14‐3‐3ζ was suppressed using RNA interference strategy. Senescence induction was determined by senescence‐associated β‐galactosidase staining and the numbers of promyelocytic leukaemia nuclear body. Real‐time PCR, western blotting and immunohistochemistry were applied for the expression of corresponding proteins. Xenograft experiment was performed to show in vivo effect of 14‐3‐3ζ silencing on tumour growth.

Results

14‐3‐3ζ silencing significantly induced senescence phenotypes via 27 accumulations. Subsequently, we demonstrated that p27 accumulation is linked to inactivation of SCF^Skp2 complex activity, probably due to the deneddylation of cullin‐1 (Cul‐1) as follows. (a) Neddylated Cul‐1 is decreased by 14‐3‐3ζ silencing. (b) Blocking neddylation using MLN4924 reproduces senescence phenotypes. (c) Knockdown of CSN5, which functions as a deneddylase, was shown to restore the senescence phenotypes induced by 14‐3‐3ζ depletion. Finally, we demonstrated that 14‐3‐3ζ depletion effectively hindered the proliferation of Hep‐2 cells implanted into nude mice.

Conclusion

14‐3‐3ζ negatively regulates senescence in Hep‐2 cells, suggesting that 14‐3‐3ζ targeting may serve to suppress the expansion of laryngeal cancer via induction of senescence through the Cul‐1/SCF^Skp2/p27 axis.

Cullin-1 promotes cell proliferation via cell cycle regulation and is a novel in prostate cancer

BACKGROUND

There is no reliable marker available for early detection, diagnostic confirmation, or disease prognosis available of prostate cancer (PCa). We aimed to evaluate the function of Cullin-1 and unravel its underlying molecular mechanism to develop novel treatment options equivalent to PCa.

METHOD

We used immunohistochemistry to analyze the correlation between Cullin-1 expression and clinicopathologic variables and patient survival. The Cullin-1 level was tested in PCa cells. The role of regulation of Cullin-1 in PCa was applied in vitro and vivo. In addition, we further investigated the signaling pathway of Cullin-1 in prostate cancer cell proliferation.

RESULT

We first discovered that Cullin-1 expression was upregulated in human PCa tissues and inversely related with PCa differentiation. We then found that high expression of Cullin-1 protein suggested a poor prognosis in PCa patients. Also, Cullin-1 promotes PCa cell proliferation in vitro and tumor growth in vivo. We then found that the mechanism of Cullin-1 regulation on cell-cycle progression is due to increased expression of p21 and p27, and decreased expression of cyclin D1 and cyclin E after Cullin-1 knockdown.

CONCLUSION

Cullin-1 exerts multiple biological effects in the PCa cell line. Through promoting proliferation and by countering cisplatin-induced apoptosis, Cullin-1 has been deeply implicated in the pathogenesis and development of PCa.