CKS1B, overexpressed in aggressive disease, regulates multiple myeloma growth and survival through SKP2- and p27Kip1-dependent and -independent mechanisms.
Overexpression of CKS1B, a gene mapping within a minimally amplified region between 153 to 154 Mb of chromosome 1q21, is linked to a poor prognosis in multiple myeloma (MM). CKS1B binds to and activates cyclin-dependent kinases and also interacts with SKP2 to promote the ubiquitination and proteasomal degradation of p27(Kip1). Overexpression of CKS1B or SKP2 contributes to increased p27(Kip1) turnover, cell proliferation, and a poor prognosis in many tumor types. Using 4 MM cell lines harboring MAF-, FGFR3/MMSET-, or CCND1-activating translocations, we show that lentiviral delivery of shRNA directed against CKS1B resulted in ablation of CKS1B mRNA and protein with concomitant stabilization of p27(Kip1), cell cycle arrest, and apoptosis. Although shRNA-mediated knockdown of SKP2 and forced expression of a nondegradable form of p27(Kip1) (p27(T187A)) led to cell cycle arrest, apoptosis was modest. Of importance, while knockdown of SKP2 or overexpression of p27(T187A) induced cell cycle arrest in KMS28PE, an MM cell line with biallelic deletion of CDKN1B/p27(Kip1), CKS1B ablation induced strong apoptosis. These data suggest that CKS1B influences myeloma cell growth and survival through SKP2- and p27(Kip1)-dependent and -independent mechanisms and that therapeutic strategies aimed at abolishing CKS1B function may hold promise for the treatment of high-risk disease for which effective therapies are currently lacking.
Zhan
Fenghuang
F
Donna D and Donald M. Lambert Laboratory of Myeloma Genetics at the Myeloma Institute for Research and Therapy, University of Arkansas for Medical Sciences, 4301 W. Markham Street, Little Rock, AR 72205, USA. zhanfenghuang@uams.edu
Colla
Simona
S
Wu
Xiaosong
X
Chen
Bangzheng
B
Stewart
James P
JP
Kuehl
W Michael
WM
Barlogie
Bart
B
Shaughnessy
John D
JD
D042846:CDC2-CDC28 Kinases; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000502:physiology; D053148:Caspase 3 / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D002453:Cell Cycle; D049109:Cell Proliferation; D002470:Cell Survival; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000096:biosynthesis*; D018844:Cyclin-Dependent Kinases / Q000096:biosynthesis* / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D009101:Multiple Myeloma / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D010950:Plasma Cells / Q000378:metabolism; D044786:S-Phase Kinase-Associated Proteins / Q000096:biosynthesis*
C093090:CKS1B protein, human; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D044786:S-Phase Kinase-Associated Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D042846:CDC2-CDC28 Kinases; D018844:Cyclin-Dependent Kinases; D053148:Caspase 3; D020169:Caspases