Fibronectin turnover in human mesangial cell cultures as affected by Adriamycin

Abstract

Fibronectin (FN) turnover and turnover changes induced by the anticancer drug Adriamycin (ADR) were measured in human mesangial cells (HMC) in vitro. HMC cultures synthesize cellular FN (2.2 +/- 0.3% of total protein synthesis; n = 12) which is secreted and incorporated into a fibrillar extracellular matrix (ECM). A 24 hr incubation of HMC with ADR (0.5-5 micrograms/ml) resulted in an accumulation of FN in the culture medium, with a maximum increase following 5 micrograms/ml (7.3 +/- 2.3 pg/cell vs. controls: 4.4 +/- 1.9 pg/cell; n = 10). Correspondingly, radioactively labeled immunoprecipitable FN was increased in a dosage-dependent manner in the culture medium up to 50% vs. controls. The incorporation of radioactively labeled FN into ECM was significantly increased following 2 micrograms ADR/ml. In accordance, immunofluorescence staining revealed an expansion of pericellular FN fibers in cultures exposed to 2 micrograms ADR/ml. Concomitant with the accumulation of extracellular FN, radioactively labeled FN in the cells was reduced by 22%. Qualitative characterization of FN patterns revealed a diminished number of degradation products in the culture medium of ADR-treated HMC. These data suggest that ADR interferes with the turnover of FN secreted by HMC in vitro in such a way that FN accumulates extracellularly. This in turn leads to a reduced FN synthesis. These findings are compatible with a loss of urinary FN degradation products accompanying the onset of proteinuria in ADR-treated rats.

Glomerular compromise in mercuric chloride-induced nephrotoxicity

“…Treated rats presented higher fibronectin levels in the urine as compared with control animals. It could be a result of the enhanced glomerular permeability for plasma fibronectin and a loss of urinary fibronectin or fibronectin-degradation products derived from renal cellular fibronectin (10). It was previously reported a desquamation of tubular structures produced by mercury injury (4).…”

“…The roles assigned to the mesangium include structural support to the glomerulus, modulation of capillary surface area, participation in plasma ultrafiltration, and a variety of metabolic and secretory activities (8). The formation of mesangial extracellular matrix (ECM) is of special importance to the glomerulus since it is closely related to the mesangial function.…”

Cell Adhesion Mediated Drug Resistance (CAM-DR): Role of Integrins and Resistance to Apoptosis in Human Myeloma Cell Lines

“…53,54 DNA damaging agents such as doxorubicin or melphalan may also induce increased production of ligand, as was shown with human mesangial cell cultures and FN synthesis. 55 Cells under selection pressure may then use soluble or cell-bound integrin ligands, and subsequent α 4 -mediated signaling, as a cytoprotective mechanism.…”

New insights into the role of extracellular matrix during tumor onset and progression

“…Production of ECM components such as fibronectin (Soose et al, 1993) is also upmodulated by drug treatment of tumor cells. In vitro data indicate that DXR perturbs the turnover of fibronectin secreted by human mesangial cells such that it accumulates extracellularly (Soose et al, 1993). We recently detected upmodulation of mRNA for fibulin-1, a molecule involved in laminin polymerization, after treatment of breast carcinoma cells with DXR (Fig.…”