Expression of cell-cycle-regulated proteins pRb2/p130, p107, p27(kip1), p53, mdm-2, and Ki-67 (MIB-1) in prostatic gland adenocarcinoma.
OBJECTIVE
The quest for prognostic molecular markers in prostatic carcinoma is still in progress. Many proteins have already been screened by immunohistochemistry with the aim to find the most reliable indicator of progressive disease. In this study, we evaluated the expression of pRb2/p130, p107, p27(kip1), p53, mdm-2, and Ki-67 (MIB-1) by immunohistochemistry in 24 prostate carcinomas compared with the paired expression of normal prostates.


METHODS
Expression of the different proteins in normal and pathological specimens was evaluated by the Wilcoxon test. A matrix of correlation (Spearman coefficient) was used to evaluate the possible association in expression among the different proteins. Logistic regression analysis was used to test the multivariable prognostic value of the levels of protein expression for the probability of disease development.


RESULTS
p53 and Ki-67 (MIB-1) showed a higher expression in cancer than in normal tissue (P = 0.006 and <0.001, respectively). pRb2/p130, p107, and p27(kip1) showed an overall lower expression in cancer, but the difference between cytoplasmic and nuclear expression was always higher for cancer (Ps, from <0.001 to 0.016). mdm-2 expression was lower in cancer, but the difference between cytoplasmic and nuclear expression was not significant (P = 0.571) when compared with that in normal tissue. A positive correlation between p27 and pRb2/p130 levels expressed, in normal and cancer counterparts in the same sample, as the difference between cytoplasmic and nuclear protein concentrations (P = 0.045) was found. Additionally, p107 expression showed an inverse correlation with Ki-67 (MIB-1) expression in the most aggressive tumors (P = 0.046). Logistic regression output showed that Ki-67 (MIB-1) and pRb2/p130 (expressed as differences between cytoplasmic and nuclear concentrations) were the variables associated with a higher risk of cancer. The highest value was reported for Ki-67 (MIB-1) (odds ratio, 2.11), followed by pRb2/p130 (odds ratio, 1.01). pRb2/p130 alone was associated with a sensitivity (rate of cases having a posterior probability of disease >/=0.5) of 61% with a false positive rate of 22%. Ki-67 (MIB-1) alone yielded a sensitivity of 69% and a false positive rate of 14%. The combined model (Ki-67 + pRb2/p130) yielded a sensitivity of 83% with a false positive rate of 17%. Interestingly, one specimen in which we also found a high-grade prostatic intraepithelial neoplasia showed the progressive loss of pRb2/p130 from normal prostatic cells to prostatic intraepithelial neoplasia cells, suggesting that in prostatic cancer, lack of expression of the tumor suppressor gene pRb2/p130 could be involved in the progression of the disease, from an early stage.


CONCLUSIONS
This study showed that all of the proteins but mdm-2 were expressed at a different rate in normal and pathological prostate specimens. Multivariate analysis showed that pRb2/p130 and p107 may be involved in the pathogenesis and progression of prostate cancers, and that the expression of the retinoblastoma-related protein pRb2/p130 along with Ki-67 (MIB-1), expressed as differences between cytoplasmic and nuclear concentrations, could be considered new parameters to be evaluated in discriminating patients at a higher risk for prostate cancer.
Claudio
Pier Paolo
PP
Sbarro Institute for Cancer Research and Molecular Medicine, Temple University, 1900 North 12th Street, Philadelphia, PA 19122, USA.
Zamparelli
Alessandra
A
Garcia
Fernando U
FU
Claudio
Luigi
L
Ammirati
Giuseppe
G
Farina
Antonio
A
Bovicelli
Alessandro
A
Russo
Giuseppe
G
Giordano
Giovan Giacomo
GG
McGinnis
David E
DE
Giordano
Antonio
A
Cardi
Gaetano
G
D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D050760:Cyclin-Dependent Kinase Inhibitor p27; D006801:Humans; D007124:Immunoenzyme Techniques; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D011506:Proteins; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2; D050720:Retinoblastoma-Like Protein p107; D050717:Retinoblastoma-Like Protein p130; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D019394:Ki-67 Antigen; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; C493844:RBL1 protein, human; C493837:RBL2 protein, human; D050720:Retinoblastoma-Like Protein p107; D050717:Retinoblastoma-Like Protein p130; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2