Long-term persistence of acquired resistance to 5-fluorouracil in the colon cancer cell line SW620.

Treatment resistance to antineoplastic drugs represents a major clinical problem. Here, we investigated the long-term stability of acquired resistance to 5-fluorouracil (FU) in an in vitro colon cancer model, using four sub-clones characterised by increasing FU-resistance derived from the cell line SW620. The resistance phenotype was preserved after FU withdrawal for 15weeks (~100 cell divisions) independent of the established level of drug resistance and of epigenetic silencing. Remarkably, resistant clones tolerated serum deprivation, adopted a CD133(+) CD44(-) phenotype, and further exhibited loss of membrane-bound E-cadherin together with predominant nuclear ß-catenin localisation. Thus, we provide evidence for a long-term memory of acquired drug resistance, driven by multiple cellular strategies (epithelial-mesenchymal transition and selective propagation of CD133(+) cells). These resistance phenomena, in turn, accentuate the malignant phenotype.

Circulating matrix metalloproteinases and their inhibitors in inguinal hernia and abdominal aortic aneurysm.

AIM: There is evidence supporting the role of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) in aortic and abdominal wall connective tissue degeneration, resulting in aneurysm and hernia formation. Furthermore, clinical association studies have demonstrated increased prevalence of abdominal wall hernias in patients with aortic aneurysms. Our objective was to estimate the levels of MMPs and TIMPs in the blood of patients with aortic aneurysm and inguinal hernia, in order to investigate whether there is potential pathogenic linkage of impaired collagen metabolism. METHODS: Plasma concentrations of MMP-9, MMP-2, TIMP-1 and TIMP-2 were quantified using ELISA in 33 male patients with abdominal aortic aneurysm and 91 male patients with inguinal hernia. They were consecutive patients undergoing repair during the study period. The same substances were measured in 35 healthy male controls. RESULTS: MMP-9 and MMP-2 concentrations were lower in the plasma of patients with inguinal hernia and abdominal aortic aneurysm than controls, with hernia patients having the lowest circulating levels. The levels of TIMP-2 were significantly elevated in patients with inguinal hernia and significantly reduced in patients with aortic aneurysm, whereas opposite correlations were found for circulating TIMP-1. CONCLUSION: Different patterns of circulating MMP and TIMP levels were found in patients with aneurysm and hernia compared with controls. Underlying pathogenic processes implicating MMPs and TIMPs in connective tissue metabolism are expressed by differing plasma levels in the two disease states. Further research including combined plasma and tissue analyses is required to further investigate potential common pathogenesis of these diseases.

Gelatinases [matrix metalloproteinase-2 (MMP-2) and MMP-9] induce carotid plaque instability but their systemic levels are not predictive of local events.

Matrix metalloproteinases (MMPs) appear to play a central role in atherosclerotic plaque remodeling; however, the relationship of increased MMP levels in inducing carotid plaque instability remains controversial. We investigated whether gelatinases (MMP-2 and MMP-9) are implicated in carotid intraplaque hemorrhage and whether their serum levels may predict local carotid events. Nineteen carotid specimens obtained by endarterectomy of 18 patients were studied. The presence of gross intraplaque hemorrhage was recorded before plaque removal and quantification of MMP-2, MMP-9, and tissue inhibitor of metalloproteinase-1 (TIMP-1) in extracts from (1) the more stenotic area of the plaque, (2) the periphery of the plaque, and (3) serum was performed by enzyme-linked immunosorbent assay. MMP-9 levels measured in extracts from the most stenotic area were significantly higher in patients with intraplaque hemorrhage (p = 0.007); however, serum levels showed no difference, while those taken from the periphery of the lesion were also increased but did not reach a statistically significant level (p = 0.06). An increase in MMP-2 values was observed in the periphery of the lesion (p = 0.04) in patients with intraplaque hemorrhage. TIMP-1 levels showed no difference between the two groups regardless of the presence or absence of intraplaque hemorrhage. No significant differences in MMP levels were observed between symptomatic and asymptomatic patients. Increased levels of MMPs, particularly MMP-9, have been implicated in carotid intraplaque hemorrhage without their serum levels being predictive of local events.