Preclinical and clinical studies of MMP inhibitors in cancer

The role of matrix metalloproteinases in tumor angiogenesis and growth is now well recognized for models of both human and animal cancer. Clinical studies currently under way with the prototype matrix metalloproteinase inhibitor, marimastat, will establish whether inhibitors of these enzymes are of benefit in the treatment of different types of human cancer. On chronic therapy in humans, marimastat induces a reversible tendinitis that can also be detected in certain animal species. This paper compares the ability of broad-spectrum and various types of selective matrix metalloproteinase inhibitors to induce tendinitis and to exhibit anticancer effects in an animal cancer model. Under conditions in which both systemic exposure and inhibitor potency are controlled, selective inhibitors are less pro-tendinitic, but are weaker anticancer agents than broad-spectrum agents such as marimastat. The clinical relevance of these findings is discussed.

The synthesis of novel matrix metalloproteinase inhibitors employing the Ireland-Claisen rearrangement

Matrix metalloproteinase inhibitors of general formula (1) were synthesised by a route involving an Ireland-Claisen rearrangement which enables systematic modification of the substituent alpha to the hydroxamic acid. An analogue (12c) possessing an alpha-cyclopentyl group is a potent broad spectrum inhibitor that displays high and sustained blood levels following oral dosing in both the rat and marmoset ex-vivo bioassays. This compound and analogues are also potent inhibitors of TNF alpha release.

Matrix metalloproteinases and processing of pro-TNF-alpha

Tumor necrosis factor-alpha (TNF-alpha) is released from a cell membrane-anchored precursor by proteolytic cleavage. We have shown that broad spectrum synthetic inhibitors of matrix metalloproteinases (MMPs) prevent the processing of the TNF precursor but do not inhibit the release of other cytokines. Purified MMPs, stromelysin, matrilysin, collagenase, and the gelatinases can all cleave a recombinant pro-TNF substrate to yield mature TNF. MMP inhibitors prevent the rise in blood levels of TNF after endotoxin administration in rats and are effective in animal models of inflammatory disease such as adjuvant arthritis. Drugs that inhibit MMP action and TNF release show great promise for the treatment of autoimmune inflammatory diseases.

Processing of tumour necrosis factor-alpha precursor by metalloproteinases

Tumour necrosis factor-alpha (TNF-alpha) is a potent pro-inflammatory and immunomodulatory cytokine implicated in inflammatory conditions such as rheumatoid arthritis, Crohn's disease, multiple sclerosis and the cachexia associated with cancer or human immunodeficiency virus infection. TNF-alpha is initially expressed as a 233-amino-acid membrane-anchored precursor which is proteolytically processed to yield the mature, 157-amino-acid cytokine. The processing enzyme(s) which cleave TNF-alpha are unknown. Here we show that the release of mature TNF-alpha from leukocytes cultured in vitro is specifically prevented by synthetic hydroxamic acid-based metalloproteinase inhibitors, which also prevent the release of TNF-alpha into the circulation of endotoxin challenged rats. A recombinant, truncated TNF-alpha precursor is cleaved to biologically active, mature TNF-alpha by several matrix metalloproteinase enzymes. These results indicate that processing of the TNF-alpha precursor is dependent on at least one matrix metalloproteinase-like enzyme, inhibition of which represents a novel therapeutic mechanism for interfering with TNF-alpha production.

Synthesis and biological evaluation of dihydroeptastatin, a novel inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase

The total synthesis of the novel hydroxylated HMG-CoA reductase inhibitor dihydroeptastatin (7) is described. The key C-3 hydroxyl group is introduced via a Baeyer-Villiger reaction on the methyl ketone 17 which is obtained in three high-yielding steps from the known tricyclic lactone 12. In an isolated enzyme assay dihydroeptastatin had a similar IC50 to mevinolin but in cellular assays using Hep G2 and HES 9 cell lines, dihydroeptastatin was much less potent. No selectivity between the two cell lines was observed.

Effects of physical activity on risk factors for coronary heart disease in previously sedentary women: a five-year longitudinal study

Fitness, weight, blood-pressure, and lipids were measured in 290 women joining a fitness programme. Five years later, 110 (38%) had remained active, and the others had become sedentary again. The net effect of being active was to increase fitness by 18% and to reduce weight by 1.9 kg, diastolic blood pressure by 3 mmHg, and triglycerides by 0.15 mmol/L-1. After controlling for age, weight and fitness, physical activity accounted for 1% and 3% of the variance of changes in systolic and diastolic blood pressure respectively, and was not associated with changes in lipids. Change in fitness accounted for only 1% of change in diastolic blood pressure. More 'active' women gave up smoking than 'inactive' (70% versus 10%). Hypertensive women were more sensitive to changes in weight and fitness than normotensive women. It was concluded that physical activity and change in fitness were only weakly related to changes in blood pressure and were unrelated to changes in lipids.

Relationships between physical fitness and risk factors for coronary heart disease in men and women

The aim of the study was to examine the cross-sectional relationships between physical fitness and risk factors for coronary heart disease (CHD). Measurements were made of fitness (defined as predicted maximal oxygen uptake), blood pressure, total cholesterol, triglycerides, and glucose in 1500 healthy men and women aged 20 to 65 years. After controlling for the effects of age, physique, smoking, alcohol use and stress, by multiple regression analyses, it was found that fitter men had lower blood pressure, cholesterol, and triglycerides than less fit men, and fitter women had lower blood pressure than less fit women. However, these fitness/risk factor relationships were seen as weak trends, probably of minor clinical importance. It is emphasised that such cross-sectional data should not be interpreted as support for the popular claim that people who increase their fitness can expect to improve their CHD risk factor status.

Relationships between weight change and changes in blood pressure and serum lipids in men and women

An examination was made of the relationships between weight change and changes in blood pressure and serum lipids over a five-year period in apparently healthy men and women not engaging in a systematic regime of diet and/or weight control. Weight change was positively correlated with systolic and diastolic blood pressure, cholesterol, and triglycerides, though the correlation coefficients were small (0.11 to 0.28) and not statistically significant for systolic blood pressure and cholesterol for men, and triglycerides for women. After controlling for the effects of differences in age, weight, physical work capacity and initial values in risk factors, and for changes in physical work capacity, weight change in women was found to account independently for a proportion of the variance of changes in systolic blood pressure (3 per cent), diastolic blood pressure (6 per cent), and cholesterol (2 per cent); in men weight change was independently related only to change in diastolic blood pressure (4 per cent). Subjects with elevated blood pressure (diastolic greater than or equal to 95 mmHg) were apparently more sensitive to weight change than those with 'normal' blood pressure. It was concluded that in free-living populations the relationships between weight change and changes in blood pressure and lipids are not strong, and that the general value of weight control in this context may have been exaggerated.

A pilot study of some associations between behavioural stressors and physiological processes in healthy men

A study was made of the physiological effects of smoking, psychological stressors, heat, exercise, and fat ingestion on 12 healthy men. Repeated measurements were made of cardiovascular, neuroendocrine, enzyme, lipid, and other variables in all stressor situations. The main findings were that psychological stressors and exercise were associated with more and larger physiological changes than the other stressors, and widespread response differences in addition to those in lipids were identified between subgroups of seven normolipidaemic men and five hypertriglyceridaemic men.