RESUMEN
Despite the success of CD20 antibody rituximab in immunotherapy, acquired resistance is one of the prime obstacles for the successful treatment of B-cell malignancies. There is an urgent need to intensify efforts against resistance in cancer treatment. Growing evidence indicated that lysosomes may form an "Achilles heel" for cancer cells by sensitizing them to death pathways. Here, we uncover an important role of CD20 in initiation of ceramide/lysosomal membrane permeabilization (LMP)-mediated cell death, showing that colocalization of CD20-TNFR1 after type II CD20 antibody ligation can stimulate de novo ceramide synthesis by ceramide synthase and consequently induce remarkable lysosomal permeabilization (LMP) and lysosome-mediated cell death. Further studies show that the potent lysosome-mediated cell death induced by CD20 antibodies exhibits a profound killing effect against both rituximab-sensitive and -resistant (RR) lymphoma. Furthermore, engineering of rituximab by introducing a point mutation endows it with the ability to induce potent ceramide/LMP-mediated cell death in both RR lymphoma and primary B-cell malignancies from patients with rituximab-refractory, suggesting the potential clinical application to combat rituximab resistance.
RESUMEN
OBJECTIVE: To investigate the effects of atorvastatin (AVT) on renal function and renal pathological changes in the aged rat and explore their possible mechanisms. METHODS: Twenty-month-old, normal female Wistar rats were divided into three groups: group A (n=8) was fed high-dose AVT (10mg/kg/d); group B (n=8) was fed low-dose AVT (1mg/kg/d); and group C (controls, n=8) received the same volume of normal saline; 3-month-old, normal female Wistar rats served as young normal controls (n=8). All rats were sacrificed following a 4-month treatment period. Serum creatinine and blood lipid levels were measured. The glomerular sclerosis index and tubulointerstitial lesions were determined using renal periodic acid-Schiff-stained paraffin sections. The mRNA and protein expressions of matrix metalloproteinases (MMP)-9 and -2, tissue inhibitors of metalloproteinase (TIMP)-1 and -2, transforming growth factor-ß1 (TGF-ß1), and peroxisome proliferator-activated receptors (PPARs) were examined using reverse transcription polymerase chain reactions and Western blots, respectively. RESULTS: Serum lipid (including serum cholesterol and serum triglycerides) levels in aged rats were significantly higher than those in young rats (p<0.05). Compared to the aged control group, high-dose AVT was associated with significantly lower serum total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels in aged rats (p<0.05); low-dose AVT was associated only with lower serum LDL-C levels (p<0.05). Renal morphological changes in aged rats included focal glomerulosclerosis, infiltration of inflammatory cells, and arteriole sclerosis. Improved renal pathology was observed in aged, AVT-treated rats, and included a decreased glomerular sclerosis index and tubulointerstitial lesion score, especially in those receiving high-dose AVT. Additionally, renal artery wall thickening, luminal narrowing, and arteriolosclerosis were significantly less severe in aged rats receiving high-dose AVT. Upregulated expression of MMP-9 and TGF-ß1 was observed in the renal tissue of aged rats. AVT treatment was associated with a reversal of these phenomena and upregulated expression of TIMP-1, PPARα, PPARß, and PPARγ in aged rats. CONCLUSION: AVT improved the renal pathology of aged rats. These effects may have been induced by the lowering of blood lipids, maintaining the MMP/TIMP balance, and downregulating the expression of TGF-ß1. AVT may reduce the levels of MMP-9 and TGF-ß in aged rats by upregulating the expression of PPARs.