Raf kinase inhibitor protein expression in a survival analysis of colorectal cancer patients.
OBJECTIVE
Raf kinase inhibitor protein (RKIP) inhibits the Raf and nuclear factor kappa B signaling pathways, and suppresses metastasis in animal models. We examined whether RKIP expression in primary colorectal cancers (CRCs) correlates with the risk of metastasis and overall survival.


METHODS
RKIP expression was examined immunohistochemically in three separate cohorts: a tissue microarray containing 276 samples from human tumors and normal tissues, and retrospective studies of 268 CRC patients and 65 early-stage CRCs. Overall and metastasis-free survival rates were measured.


RESULTS
RKIP was expressed in normal epithelia but was reduced in metastatic tumors. RKIP expression in primary CRC was an independent prognostic marker for survival using multivariate Cox regression analysis (hazard ratio, 2.808; 95% CI, 1.58 to 4.96; P = .0002), independent of Dukes' stage. Patients with Dukes' C RKIP-positive tumors had similar 5-year survival rates as early-stage patients if tumors had equivalent RKIP expression levels. An independent study of early-stage CRCs confirmed that reduced RKIP expression predicted metastatic recurrence and reduced disease-free survival (hazard ratio, 4.5; 95% CI, 1.7 to 12.3; P = .003). RKIP expression was independent of sex, age, mitotic index, lymphatic and vascular invasion, depth of invasion, and tumor site, but correlated positively with apoptotic index (P = .024). Weak or loss of RKIP expression was the most significant and independent prognostic marker using a multivariate regression equation (hazard ratio, 4.5; 95% CI, 1.7 to 12.3; P = .003).


CONCLUSIONS
RKIP expression in primary CRCs correlates with overall and disease-free survival, and can be useful for identifying early-stage CRC patients at risk of relapse.
Al-Mulla
Fahd
F
Kuwait University, Faculty of Medicine, Safat, Kuwait.
Hagan
Suzanne
S
Behbehani
Abdulla I
AI
Bitar
Milad S
MS
George
Shirley S
SS
Going
James J
JJ
García
Jorge J Curto
JJ
Scott
Lucy
L
Fyfe
Nicky
N
Murray
Graeme I
GI
Kolch
Walter
W
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000401:mortality* / Q000473:pathology; D018572:Disease-Free Survival; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D049488:Phosphatidylethanolamine Binding Protein / Q000235:genetics / Q000378:metabolism*; D012189:Retrospective Studies; D018570:Risk Assessment
C511482:PEBP1 protein, human; D049488:Phosphatidylethanolamine Binding Protein