Takayuki Mishina

Cyclin D1 expression in non-small-cell lung cancers : its association with altered p53 expression, cell proliferation and clinical outcome

SummaryCyclin D1, like p16INK4 (p16) and retinoblastoma (RB) proteins, participates in the cell cycle control at the G1–S transition. We have previously demonstrated altered p16 and RB protein status in non-small-cell lung cancers (NSCLCs) and their potential synergistic effect with altered p53 protein on proliferative activity (Kinoshita et al (1996) Cancer Res 56: 5557–5562). In the present study, cyclin D1 expression was studied by immunohistochemistry in the same cohort of 111 resected NSCLCs as in our previous study, and the amount of the cyclin D1 gene was analysed by Southern blot analysis in 29 NSCLCs. Cyclin D1 expression was analysed in relation to the status of p53, p16 and RB proteins, and proliferative activity determined by the Ki-67 index. It was also analysed in relation to survival of 77 patients with NSCLCs which were potentially curatively resected between 1990 and 1995. We found that: (1) cyclin D1 was expressed in 13 (11.7%) of 111 NSCLCs; (2) the cyclin D1 gene was neither significantly amplified nor rearranged; (3) cyclin D1 expression significantly correlated with altered p53 protein expression (P = 0.04), whereas it did not correlate with p16 and RB protein status; (4) proliferative activity tended to be higher in cyclin D1-positive (+) tumours than in cyclin D1-negative (–) tumours, although this difference was not statistically significant (P = 0.08); and (5) patients with cyclin D1+ tumours survived longer than patients with cyclin D1– tumours (5-year survival rates, 89% and 64% respectively, by the Kaplan–Meier method; P = 0.045 by the log-rank test), and cyclin D1 expression tended to be a favourable prognostic factor (P = 0.08 in univariate analysis). These findings suggest the involvement of cyclin D1 in the development and progression of NSCLCs, their proliferative activity and clinical outcome of NSCLC patients.

Predictive value of expression of p16INK4A, retinoblastoma and p53 proteins for the prognosis of non-small-cell lung cancers.

The predictive value of expression of p16INK4A, retinoblastoma (Rb) and p53 proteins for prognosis was evaluated in 76 patients with non-small-cell lung cancers (NSCLCs) that were potentially curatively resected between 1990 and 1995, using the results of immunostaining analyses of these proteins as reported in our previous study (Kinoshita et al, 1996). Of these NSCLCs, 22 (29%) lacked p16 protein expression and eight (11%) Rb protein, while 30 (39%) showed positive (altered) p53 protein expression. Survival of patients with p16-negative tumours was not significantly different from that of patients with p16-positive tumours (5-year survival rates 67% and 72% respectively, P = 0.8), nor was survival of patients with Rb-negative tumours significantly different from that of patients with Rb-positive tumours (5-year survival rates 42% and 69% respectively, P = 0.9). Moreover, survival of patients with p16/Rb-negative (either p16- or Rb-negative) tumours was not significantly different from that of patients with p16/Rb-positive (both p16- and Rb-positive) tumours (5-year survival rates 67% and 68% respectively, P = 0.7). In contrast, survival of patients with p53-positive (altered) tumours tended to be shorter than that of patients with p53-negative (unaltered) tumours (5-year survival rates 56% and 78% respectively, P = 0.06). In univariate analysis of potential prognostic factors, p16, Rb and p16/Rb proteins were not significant prognostic factors in the present cohort of potentially curatively resected NSCLCs. Altered p53 protein status tended to be a negative prognostic factor (P = 0.06 by the univariate analysis). These results indicate that loss of p16 protein alone, or in combination with loss of Rb protein, does not predict the clinical outcome of patients with resected NSCLCs.