NEDD8 Inhibition Overcomes CKS1B-Induced Drug Resistance by Upregulation of p21 in Multiple Myeloma

Abstract

Purpose CKS1B is significantly upregulated in multiple myeloma (MM) and associated with poor prognosis. The identification of novel therapies is essential for effective treatment of patients resistant to chemotherapy. The NEDD8 inhibitor MLN4924 selectively targets SCFSkp2 activation and offers a more specific approach to protein degradation inhibition than total proteasomal inhibition. The goal of this study was to evaluate whether MLN4924 is effective in high CKS1B conditions and identify mechanisms regulating drug potency. Experimental Design Bortezomib and MLN4924 sensitivity was assessed through proliferation, viability, clonogenic potential, and senescence induction in cells overexpressing CKS1B. The mechanism for MLN4924 sensitivity was elucidated by immunoblot analysis of SCFskp substrates and confirmed by shRNA knockdown. The clinical relevance of the NEDD8 pathway was examined in GEPs derived from healthy people, patients with MGUS, and MM. Results Cells overexpressing CKS1B were resistant to bortezomib but sensitive to MLN4924. Treatment of CKS1B-overexpressing cells with MLN4924 decreased proliferation, clonogenicity, and induced senescence. MLN4924, but not bortezomib, induced stabilization of p21 and knockdown of p21 resulted in loss of MLN4924 sensitivity. Patients with MGUS and MM exhibited increased expression of NEDD8-pathway genes relative to normal plasma cells. MM patients with high NEDD8 expression were linked to bortezomib resistance in clinical trials, and had inferior outcomes. Conclusions Our data demonstrate cells with elevated CKS1B expression are resistant to bortezomib but sensitive to MLN4924 and offer a mechanism through the stabilization of p21. These findings provide rationale for targeting the NEDD8 pathway in MM patients exhibiting elevated expression of CKS1B.

MicroRNA-497 inhibits multiple myeloma growth and increases susceptibility to bortezomib by targeting Bcl-2

“…According to the findings of the present study, miR-497 inhibited proliferation and promoted apoptosis of MM cells, indicating that miR-497 may have a potential synergetic effect or sensitization to bortezomib. To confirm this hypothesis, RPMI-8226 and U266 cells, which were have been shown to be more resistant to bortezomib compared with other MM cell lines (26,27), were used. Although the cell viability was decreased when treated with bortezomib treatment alone, a lower level was detected following treatment with ≥10 nM bortezomib combined with miR-497 ( Fig.…”

“…Although bortezomib promotes the death of malignant plasma cells and is a conventional clinical medication used in MM therapy, several patients are intrinstically or become bortezomib-resistant (26,27). Therefore, RPMI-8226 and U266 MM cell lines, which are confirmed to be resistant to bortezomib (26,27), were used in the present study to verify the function of miR-497. The results may reveal a synergetic effect of miR-497 in improving bortezomib efficacy.…”

“…In addition, as miR-497 and Bcl-2 are involved in chemotherapy of other types of cancer (20,21,23), it is of interest to evaluate the possibility of the combination therapy of miR-497 and bortezomib, a common drug used for MM treatment (25). Although bortezomib promotes the death of malignant plasma cells and is a conventional clinical medication used in MM therapy, several patients are intrinstically or become bortezomib-resistant (26,27). Therefore, RPMI-8226 and U266 MM cell lines, which are confirmed to be resistant to bortezomib (26,27), were used in the present study to verify the function of miR-497.…”

Gain of chromosome 1q portends worse prognosis in multiple myeloma despite novel agent-based induction regimens and autologous transplantation

“…In addition, studies are underway to identify agents that can overcome CKS1B-induced drug resistance. [25]…”

ARNT/HIF‐1β links high‐risk 1q21 gain and microenvironmental hypoxia to drug resistance and poor prognosis in multiple myeloma

“…However, CKS1B amplification or overexpression by itself might not correlate to short survival of MM patients 46. It is also noteworthy that CKS1B expression has been determined exclusively at mRNA level so far,47 which does not necessarily reflect its protein level and function. In fact, no increase in protein level of CKS1B , neither other known MM‐related 1q21 genes (eg, PSMD4 , MCL1 ) was observed in human MM cell lines carrying 1q21 gain.…”