Statins, high-density lipoprotein cholesterol, and regression of coronary atherosclerosis.

CONTEXT: Statins reduce low-density lipoprotein cholesterol (LDL-C) levels and slow progression of coronary atherosclerosis. However, no data exist describing the relationship between statin-induced changes in high-density lipoprotein cholesterol (HDL-C) and disease progression. OBJECTIVE: To investigate the relationship between changes in LDL-C and HDL-C levels and atheroma burden. DESIGN, SETTING, AND PATIENTS: Post-hoc analysis combining raw data from 4 prospective randomized trials (performed in the United States, North America, Europe, and Australia between 1999 and 2005), in which 1455 patients with angiographic coronary disease underwent serial intravascular ultrasonography while receiving statin treatment for 18 months or for 24 months. Ultrasound analysis was performed in the same core laboratory for all of the studies. MAIN OUTCOME MEASURE: Relationship between changes in lipoprotein levels and coronary artery atheroma volume. RESULTS: During statin therapy, mean (SD) LDL-C levels were reduced from 124.0 (38.3) mg/dL (3.2 [0.99] mmol/L) to 87.5 (28.8) mg/dL (2.3 [0.75] mmol/L) (a 23.5% decrease; P<.001), and HDL-C levels increased from 42.5 (11.0) mg/dL (1.1 [0.28] mmol/L) to 45.1 (11.4) mg/dL (1.2 [0.29] mmol/L) (a 7.5% increase; P<.001). The ratio of LDL-C to HDL-C was reduced from a mean (SD) of 3.0 (1.1) to 2.1 (0.9) (a 26.7% decrease; P<.001). These changes were accompanied by a mean (SD) increase in percent atheroma volume from 39.7% (9.8%) to 40.1% (9.7%) (a 0.5% [3.9%] increase; P = .001) and a mean (SD) decrease in total atheroma volume of 2.4 (23.6) mm3 (P<.001). In univariate analysis, mean levels and treatment-mediated changes in LDL-C, total cholesterol, non-HDL cholesterol, apolipoprotein B, and ratio of apolipoprotein B to apolipoprotein A-I were significantly correlated with the rate of atherosclerotic progression, whereas treatment-mediated changes in HDL-C were inversely correlated with atheroma progression. In multivariate analysis, mean levels of LDL-C (beta coefficient, 0.11 [95% confidence interval, 0.07-0.15]) and increases in HDL-C (beta coefficient, -0.26 [95% confidence interval, -0.41 to -0.10]) remained independent predictors of atheroma regression. Substantial atheroma regression (> or =5% reduction in atheroma volume) was observed in patients with levels of LDL-C less than the mean (87.5 mg/dL) during treatment and percentage increases of HDL-C greater than the mean (7.5%; P<.001). No significant differences were found with regard to clinical events. CONCLUSIONS: Statin therapy is associated with regression of coronary atherosclerosis when LDL-C is substantially reduced and HDL-C is increased by more than 7.5%. These findings suggest that statin benefits are derived from both reductions in atherogenic lipoprotein levels and increases in HDL-C, although it remains to be determined whether the atherosclerotic regression associated with these changes in lipid levels will translate to meaningful reductions in clinical events and improved clinical outcomes.

Lung tumorigenesis associated with erb-B-2 and erb-B-3 overexpression in human erb-B-3 transgenic mice is enhanced by methylnitrosourea.

Erb-B-3 overexpression is associated with poor prognosis in non-small cell lung cancer and is often overexpressed in breast cancers. MMTVhuman-erb-B-3 transgenic mice were generated to evaluate the impact of erb-B-3 overexpression on lung and mammary gland tumorigenesis. These transgenic mice developed a high incidence of lung adenocarcinomas but not mammary gland tumors. The tumors overexpressed transgenic human [h]-erb-B-3 but also overexpressed endogenous erb-B-2, indicating that the heterodimer of h-erb-B-3-erb-B-2 was required for proliferative signal transduction to the nucleus. Lung tumor latency was shorter and the incidence higher in erb-B-3 transgenic mice treated with the methylating agent, methylnitrosourea [MNU]. In MNU treated mice, K-ras activating point mutations in codon 12, synergized with h-erb-B-3 in lung tumorogenesis. In bitransgenic MMTVrat-erb-B2/MMTV-human-erb-B-3 mice, lung tumor latency was also significantly shortened. Unlike over-expression of rat-erb-B-2, overexpression of h-erb-B-3 did not alter the incidence or latency of mammary tumors. Coupled erb-B-2 and erb-B-3 overexpression as well as K-ras activation induced signaling through mitogen-activated protein kinase (MAPK). This animal model links erb-B-3 with lung cancer, suggests that erb-B-2 and erb-B-3 heterodimerization is a necessary intermediate, and documents latency shortening by methylating agent-induced mutation of K-ras. This erb-B-3 mouse lung cancer model will help dissect genetic changes in lung tumorigenesis and may be useful for chemoprevention studies.