本周氏蛋白催化作用与多发性骨髓瘤患者肾损伤的关系

Relationship between the Catalysis of Bence Jones Protein and Renal Impairment in Patients with Multiple Myeloma

本研究通过体外细胞实验观察多发性骨髓瘤(MM)患者尿中本周氏蛋白(Bence Jones protein,BJP)酰胺酶催化作用与肾小管细胞毒性作用的关系,进一步了解BJP对MM肾损伤的毒性机制。测定13例MM患者尿BJP的酰胺酶动力学参数米氏常数(Km)和催化常数(kcat);以不同浓度BJP与猪肾小管上皮细胞(LLC-PK1)共同培养24 h后,用MTT法测定细胞增殖抑制率;以明显抑制细胞增殖的BJP浓度与LLC-PK1细胞共同培养后使用流式细胞术检测细胞凋亡。结果表明,临床出现肾损伤的MM患者尿中BJP较未出现肾损伤MM患者尿中BJP更易对LLC-PK1细胞产生毒性作用,且BJP的kcat值越高,对LLC-PK1细胞毒性作用越强。流式细胞仪检测发现,BJP能够诱导LLC-PK1细胞发生凋亡及坏死,毒性作用随BJP浓度的增高而增强。结论:BJP能够对肾小管上皮细胞产生直接毒性作用,并随BJP浓度的增高而增强;BJP酰胺酶催化作用强度与其毒性作用呈正相关,其可能是MM患者发生肾损伤的机制之一。

This study was purposed to investigate the relationship between the catalysis of Bence Jones protein（BJP） in urine of patients with multiple myeloma（MM） and toxicity on the renal proximal tubular cells in vitro,and to explore the potential mechanism for the toxicity of BJP to renal impairment in patients with MM.The Michaelis-Menten constant（Km） and catalytic constant（kcat） of the amidase activity of BJP was calculated by Hanes equation.The LLC-PK1 cells were cultured with different concentration of BJP for 24 h,then proliferation of the cells were determined by MTT method and apoptosis were determined by flow cytometry.The results showed that the BJP from the MM patients with renal impairment significantly inhibited cell proliferation,as compared with that from MM patients without renal impairment.The BJP with higher kcat had higher toxicity to LLC-PK1 cells.BJP could induce apoptosis and necrosis of LLC-PK1 cells when reached a certain concentration and this effect enhanced with increase of BJP concentration.It is concluded that the catalysis of BJP and its toxicity to renal tubular epithelial cells has a positive correlation,and toxic effect of BJP on renal tubular epithelial cells results from inhibiting proliferation and inducing apoptosis and necrosis of the cells,which may be one of renal impairment mechenisms in MM patients.