CKS1B overexpression implicates clinical aggressiveness of hepatocellular carcinomas but not p27(Kip1) protein turnover: an independent prognosticator with potential p27 (Kip1)-independent oncogenic attributes?
BACKGROUND
Through data mining the Stanford Microarray Database, the CKS1B transcript was found to be frequently upregulated in hepatocellular carcinomas (HCCs) with low alpha-fetal protein (AFP) expression. Together with SKP2, CKS1B is known to implicate p27(Kip1) protein turnover promoting cell-cycle progression.


METHODS
CKS1B, p27(Kip1), and SKP2 were immunostained in 75 HCCs and correlated with clinicopathological features, local recurrence-free survival (LRFS), and overall survival (OS). Silencing of CKS1B and SKP2 with interference short-hairpin RNA (shRNA) was performed in SK-Hep1 and Hep-3B cell lines.


RESULTS
Immunohistochemically, increased CKS1B and SKP2, and attenuated p27(Kip1) were all associated with tumor multiplicity (P < 0.05) and increasing American Joint Committee on Cancer (AJCC) stage (P < 0.05). Overexpression of CKS1B significantly correlated with advanced Okuda stages (P = 0.048) and SKP2 overexpression (P = 0.047). Neither CKS1B nor SKP2 was inversely related to p27(Kip1), which was reinforced by no alteration in p27(Kip1) abundance in HCC-derived cells with CKS1B or SKP2 silencing. Both CKS1B overexpression (P = 0.0011 and P = 0.0017) and p27(Kip1) attenuation (P = 0.0079 and P = 0.0085) were predictive of OS and LRFS, respectively, while SKP2 overexpression was associated with worse OS alone (P = 0.0043). Combined assessment of CKS1B and p27(Kip1) was able to robustly distinguish three prognostically different groups (P < 0.0001). In multivariate comparison, CKS1B overexpression represented the strongest independent adverse prognosticator [OS, P = 0.0235, hazard ratio (HR): 4.193; LRFS, P = 0.0204, HR: 4.262], followed by p27(Kip1) attenuation (OS, P = 0.0320, HR: 2.553; LRFS, P = 0.0262, HR: 2.533).


CONCLUSIONS
CKS1B protein overexpression in HCCs is implicated in clinical aggressiveness but not in p27(Kip1) turnover, implying presence of p27(Kip1)-independent oncogenic attributes. The combined assessment of CKS1B and p27(Kip1) immunoexpressions effectively risk-stratifies HCCs with different prognoses, which may aid in the management of this deadly malignancy.
Huang
Ching-Wen
CW
Department of Surgery, Yuan's General Hospital, Kaohsiung, Taiwan.
Lin
Ching-Yih
CY
Huang
Hsuan-Ying
HY
Liu
Hui-Wen
HW
Chen
Yi-Ju
YJ
Shih
Deng-Fuh
DF
Chen
Hong-Yaw
HY
Juan
Chung-Chou
CC
Ker
Chen-Guo
CG
Huang
Chi-Ying F
CY
Li
Chien-Feng
CF
Shiue
Yow-Ling
YL
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D042846:CDC2-CDC28 Kinases; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism*; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D044786:S-Phase Kinase-Associated Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D000509:alpha-Fetoproteins / Q000235:genetics / Q000378:metabolism
D014408:Biomarkers, Tumor; C093090:CKS1B protein, human; D002352:Carrier Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D044786:S-Phase Kinase-Associated Proteins; D000509:alpha-Fetoproteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D042846:CDC2-CDC28 Kinases; D018844:Cyclin-Dependent Kinases