Crescimanno M, Armata M G, Florena A M, Leonardi V, Rausa L, D'Alessandro N
Istituto di Farmacologia, Facoltà di Medicina, Università di Palermo, Policlinico P. Giaccone, Italy.
Anticancer Drugs. 1991 Oct;2(5):481-6. doi: 10.1097/00001813-199110000-00008.
A B16 melanoma line was repeatedly transplanted subcutaneously in C57BL/6 mice. On day 4 after every transplant, the animals were treated with doxorubicin (DXR), 10 mg/kg i.p. The aim of the work was to develop an in-vivo model of resistance to the antiblastic in order to analyze some possible mechanistic aspects of the process in the course of time. After 16 transplants and treatments the melanoma completely lost its sensitivity to the antiproliferative effects of maximal tolerated doses of DXR and showed over-expression of P-glycoprotein. Compared to the parental line, the in vitro resistance index was 4.6. After 27 transplants and treatments the melanoma did not increase its in vitro resistance to DXR further, and this resistance was completely reversed by verapamil. The behavior of the antioxidant defenses (superoxide dismutase, catalase, glutathione peroxidase, glutathione transferase, glutathione reductase and glutathione) was evaluated after 4, 16 and 27 transplants and treatments with DXR. At no stage did the treated melanoma show any variation in the antioxidant enzymes. Compared to the parental counterpart its glutathione levels were elevated after four treatments (+80%), when, however, the line was still sensitive to the in vivo effects of DXR, and after 16 treatments (+30%). Instead, no variation of the glutathione content was seen after 27 treatments with DXR. These results seem to exclude the possibility that the antioxidant defenses play a major role in the resistance of this B16 melanoma line to DXR. On the other hand, the low but, however, 'clinically' significant resistance of the tumor to the antiblastic seems mainly related to the mechanisms linked to the P-glycoprotein over-expression.
将B16黑色素瘤细胞系反复皮下移植到C57BL/6小鼠体内。每次移植后第4天，给动物腹腔注射阿霉素（DXR），剂量为10mg/kg。该研究的目的是建立一种对化疗药物耐药的体内模型，以便分析该过程在一段时间内可能的机制方面。经过16次移植和治疗后，黑色素瘤对最大耐受剂量DXR的抗增殖作用完全失去敏感性，并显示P-糖蛋白过表达。与亲代细胞系相比，体外耐药指数为4.6。经过27次移植和治疗后，黑色素瘤对DXR的体外耐药性没有进一步增加，且这种耐药性被维拉帕米完全逆转。在用DXR进行4次、16次和27次移植及治疗后，评估抗氧化防御（超氧化物歧化酶、过氧化氢酶、谷胱甘肽过氧化物酶、谷胱甘肽转移酶、谷胱甘肽还原酶和谷胱甘肽）的行为。在任何阶段，经治疗的黑色素瘤抗氧化酶均未显示任何变化。与亲代细胞相比，在4次治疗后（增加80%）其谷胱甘肽水平升高，然而此时该细胞系仍对DXR的体内作用敏感，在16次治疗后（增加30%）也是如此。相反，在27次DXR治疗后未观察到谷胱甘肽含量的变化。这些结果似乎排除了抗氧化防御在该B16黑色素瘤细胞系对DXR耐药中起主要作用的可能性。另一方面，肿瘤对化疗药物的低但“临床”上显著的耐药性似乎主要与P-糖蛋白过表达相关的机制有关。
