The prognostic impact of some cell cycle regulatory proteins in Egyptian breast cancer patients.

Purpose: The particular goal of this work is to study some cell cycle regulatory proteins and their potential impact on prognosis of breast cancer; p53, cyclin D1 and p27 are potential effectors being the major contributors to the control of the restriction (R) check point of the cell cycle. We also aimed to evaluate different techniques used to detect these cell cycle proteins.

Material And Methods: Forty five breast cancer patients as well as 10 controls with non malignant pathology were assessed for cell cycle regulators each by 2 different techniques; p53 was assessed by enzyme immunoassay (EIA) and immunohistochemistry (IHC), cyclin D1 by Western Blotting (WB) and IHC and p27 by WB and IHC. The cut-off was calculated as the mean of the normal controls +2 SD. Patients were followed up for 4 years and their laboratory data were correlated with different clinical parameters and with other studied regulators.

Results: Eighty seven percent of cases (39/45) were positive for p53 by EIA with a range from 20 to 4300, and a mean of 464 +/- 971 pg/mg protein. By IHC, 80% (24/30) of the cases showed varying degrees of positivity. Using WB, cyclin D1 showed high expression levels above cut off values in 69% of patients (31/45) and in 67% (20/30) by IHC. The corresponding positive figures for p27 were 82% (37/45) and 73% (22/30) using the two techniques, respectively. No significant association was found between p53, cyclin D1 and p27 on one side and different clinical parameters as lymph node status, tumor size or presence of distant metastases on the other side. Survival was poor in patients with high p53 expression. Cyclin D1 positive cases showed comparable survival with negative cases, whereas high p27 levels favored a longer disease free survival.

Conclusions: Techniques more suitable for assessment of each of these markers in our consideration were EIA for p53, WB for cyclin D1 and IHC for p27. Moreover, this study demonstrated that these markers were relevant to the biological behavior of the tumor cell per se with a possible impact on prognosis and survival, independent of other clinical prognostic factors.