The radiosensitivity of a @entity6371 ( @entity6371 ) clone and a cisplatin-resistant clone was compared with that of their parental chemosensitive cell lines. The LoVo cell line was derived from a @entity1 @entity694 , and LoVo-R was the @entity6371 clone. The @entity6371 phenotype is attributable to an increased drug efflux mediated by the P-glycoprotein and involves several classes of structurally unrelated drugs. The 2008 cell line was derived from a @entity1 @entity43 and @entity18361 was the cisplatin-resistant clone. Reduced cisplatin accumulation and elevated plasma membrane potential partially account for the drug resistance of @entity18361 cells. The chemoresistance of LoVo-R and @entity18361 cells was confirmed by cytotoxicity tests consisting of 24-hour paclitaxel and 1-hour cisplatin incubation, respectively. The radiosensitivity was evaluated by a clonogenic test. The dose-reducing cell survival fraction from 1 to 0.37 (D(0)), the quasi-threshold dose (Dq), and the survival fraction (SF) after 2 or 4 Gy were determined for each cell line. D(0), Dq, and SF(2) were 1.3 +/- 0.4 Gy, 2.1 +/- 0.6 Gy, and 43 +/- 4% for the LoVo cell line and 1.0 +/- 0.2 Gy, 1.7 +/- 0.4 Gy, and 45 +/- 8%, respectively, for the LoVo-R cell line. D(0), Dq, and SF(4) were 1.7 +/- 0.3 Gy, 3.1 +/- 0.4 Gy, and 43 +/- 12% for 2008 cells and 2.6 +/- 0.5 Gy, 4.3 +/- 0.6 Gy, and 53 +/- 11%, respectively for @entity18361 cells. No significant differences were found between LoVo and LoVo-R cells, whereas @entity18361 cells showed a significantly greater D(0,) Dq, and SF(4) than 2008 cells (p <0.05). Incubation of 2008 and @entity18361 cells with subcytotoxic buthionine (BSO) before and after irradiation partially restored @entity18361 radiosensitivity. In fact, D(0) dropped from 2.8 +/- 0.1 to 2.0 +/- 0.3 Gy in @entity18361 cells with and without BSO, whereas it was 1.9 +/- 0.2 Gy in 2008 cells in the absence and presence of BSO. The total glutathione content (GSH) of @entity18361 cells was 1.5-fold higher than that of 2008 cells. BSO treatment caused a partial depletion of GSH in 2008 and @entity18361 cells, but their radiosensitivity did not change accordingly.

Radiosensitivity in XXXX and cisplatin-resistant @entity1 carcinoma cell lines.

@entity1 :: ('9606', 'Species') :: ['human'] @entity43 :: ('MESH:D010051', 'Disease') :: ['ovary carcinoma'] @entity6371 :: ('MESH:D018088', 'Disease') :: ['multidrug-resistant', 'MDR'] @entity18361 :: ('3229', 'Gene') :: ['C13'] @entity694 :: ('MESH:D003110', 'Disease') :: ['colon carcinoma']
@entity6371 :: (MESH:D018088,Disease) :: ['multidrug-resistant']
