Correlations of cell cycle regulators (p53, p21, pRb and mdm2) and c-erbB-2 with biological markers of proliferation and overall survival in breast cancer.
OBJECTIVE
The biological impact of cell cycle regulatory proteins on breast cancer progression is widely recognised, although mostly unclear. The aim of this preliminary study was to investigate the correlations of several cell cycle modulators (p53, p21, pRb, and mdm2) and c-erbB-2 expression with cell proliferation markers (S-phase fraction [SPF] and Ki-67) and overall survival in breast cancer.


METHODS
The series comprised 50 women with stage I-II invasive ductal breast carcinoma (median follow-up 87 months), who were selected for their tumour proliferative characteristics (15 low, 15 high, and 20 intermediate proliferative tumours). Tumour differentiation was assessed following the Nottingham grading criteria. Cell cycle regulators, oestrogen receptor status, and Ki-67 index were analysed by immunohistochemistry on paraffin embedded material (cut-offs 10%). c-erbB-2 was evaluated according to a standardised immunohistochemical assay and borderline cases were confirmed by FISH analysis. Ploidy and SPF were determined by DNA flow cytometry on frozen samples. Chi-square test and Fisher's exact test were applied to analyse the statistical significance of data.


RESULTS
Positive immunostaining was observed in nine (18%) p53+, 30 (60%) p21+, 13 (26%) pRb+, and one (2%) mdm2+ cases. c-erbB-2 expression was considered positive in 11 (22%) cases. In the subset of patients dead of the disease, a high incidence of c-erbB-2 over-expression (7/10, 70%) was verified. In general, no significant correlations among cell cycle regulators or between the latter and histopathological or proliferative characteristics were found. Only the p53-/p21+ phenotype significantly correlated with low SPF (p=0.048), and p21 positivity showed a trend to be associated with low SPF (p=0.083). No statistically significant correlations between cell cycle inhibitors and clinical outcome were found. On the contrary, c-erbB-2 over-expression showed significant correlations with DNA aneuploidy (p<0.001), high SPF (p<0.001), high tumour grading (p=0.008), lack of oestrogen receptors (p=0.036), and poor overall survival (p<0.001).


CONCLUSIONS
The results seem to indicate the lack of correlations of cell cycle regulatory proteins with cell proliferation markers and overall survival in breast cancer, in contrast to c-erbB-2 over-expression which was found to be associated with increased proliferation rate and worse prognosis.
Pinto
António E
AE
Departamento de Patologia Morfológica, Instituto Português de Oncologia de Francisco Gentil, Centro Regional Oncológico de Lisboa, SA, Portugal. aepinto@ipolisboa.min-saude.pt
André
Saudade
S
Laranjeira
Cátia
C
Soares
Jorge
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000378:metabolism* / Q000401:mortality*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008875:Middle Aged; D009687:Nuclear Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D016160:Retinoblastoma Protein / Q000378:metabolism; D013534:Survival; D016019:Survival Analysis; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D051736:Proto-Oncogene Proteins c-mdm2; D018719:Erb-b2 Receptor Tyrosine Kinases; D016160:Retinoblastoma Protein; D016159:Tumor Suppressor Protein p53; C493956:CDKN1A protein, human; C497206:MDM2 protein, human