Study of the Characterization of Side Population Cells in Endometrial Cancer Cell Lines: Chemoresistance, Progestin Resistance, and Radioresistance.

Introduction: Radiotherapy, combined regimens as platinum-paclitaxel chemotherapy and/or endocrine therapy is an important adjuvant treatment after surgery for endometrial cancer (EC). While, the resistance to them remain unclear. In our study, to separate the characteristics of side population (SP) cells from EC cell lines, study the mechanism of Taxol-resistance, progestin resistance and radioresistanc, and provide the basic for EC. Methods: SP cells from EC cell lines HEC-1A, Ishikawa and RL95-2 were separated by Hoechst 33342 staining and flow cytometry analysis. The expression of breast cancer resistance protein (BCRP) in SP cells and non-SP cells from HEC-1A was examined by immunocytochemistry, and the radiation-resistant and Taxol-resistant characteristics of SP cells and non-SP cells were compared by MTS. Ishikawa, Ishikawa-SP, and Ishikawa-non-SP cells incubated with MPA were selected for cell apoptosis assays by using flow cytometry. The expression of caspase-3 was examined by immunocytochemistry, and autophagy was detected by MDC staining. Results: Small proportions of SP cells, namely, 1.44 ± 0.93%, 2.86 ± 3.09%, and 2.87 ± 1.29%, were detected in HEC-1A, Ishikawa and RL95-2, respectively. There was a stronger clone formation efficiency for the SP cells than for non-SP cells in HEC-1A [(6.02 ± 1.17) vs. (0.53±0.20)%, P = 0.001], and there was a significant difference in the rate of tumourigenicity between the SP cells and non-SP cells in HEC-1A (87.5 vs. 12.5%). There were higher levels of BCRP expression (P = 0.001) and resistance to Taxol and radiation (P < 0.05) in the SP cells than in non-SP cells. After MPA treatment, the apoptosis rates were significantly different among the Ishikawa, Ishikawa-SP and Ishikawa-non-SP groups [(4.64 ± 0.18)%, (4.01 ± 0.43)%, and (9.3 ± 0.67)%; (P = 0.05)], and the expression of Caspase-3 in the Ishikawa group was higher than that in Ishikawa-SP group. The autophagic activity of the Ishikawa-SP cells was the strongest, while the autophagic activity of Ishikawa-non-SP was the weakest. Conclusions: There is a significant enrichment in SP cells among different EC cell lines, and these SP cells be more resistant to Taxol, MPA and radiation therapy. The overexpression of BCRP among SP cells may be the cause of resistance to Taxol, progestin and radiotherapy, which may be related to apoptosis and autophagic activity.

Evaluation of whether serum tumor markers in patients with epithelial ovarian carcinoma change following chemotherapy.

BACKGROUND: Phenotypic and genotypic heterogeneity is a known feature of many cancers. Whether serum tumor marker kinds vary and change following chemotherapy is still unclear. The aim of this study was to investigate whether there is a change in the expression of serum tumor markers following chemotherapy, and the potential clinical significance in patients with epithelial ovarian carcinoma (EOC) or primary serous peritoneal carcinoma (PSPC). METHODS: Samples were collected before surgery, during chemotherapy and during follow-up for enzyme-linked immunosorbent assay (ELISA)-based evaluation of serum CA-125, CA19-9 and CP2 levels in patients with EOC or PSPC who had received primary debulking surgery followed by adjuvant chemotherapy. In total, 72 patients were examined, including 37 patients with recurrent lesions and 35 patients receiving first-line chemotherapy. RESULTS: In 35 de novo patients, 20% (7/35) demonstrated a significant changed serum tumor marker kinds among whom the patients with mucinous carcinoma (57.1%, 4/7) showed resistance to chemotherapy. In the 37 recurrent patients, 51.4% (19/37) had changed serum tumor markers, of whom 57.9% (11/19) presented with serous carcinoma. There was no significant difference in median progression-free survival or overall survival in patients with drug-sensitive or drug-resistant recurrence in patients with changed tumor marker kinds relative to those with unchanged markers. However, for patients with changed serum tumor markers there was a trend towards prolonged survival compared with the unchanged serum tumor marker group. In the 17 patients with secondary recurrence, 37.5% (6/17) had changed tumor marker levels. The ratios of CA-125/CP2 and CA-125/CA19-9 were significantly different after either chemotherapy or recurrence. CONCLUSIONS: Serum tumor marker expression in patients with EOC or PSPC may change after chemotherapy or recurrence, indicating that in addition to the markers that are abnormal before surgery, those markers that are normal should also be monitored during chemotherapy and follow-up.

[Establishment of cisplatin-resistant human endometrial cancer cell line and the study of its resistant mechanisms].

OBJECTIVE: To establish the cisplatin (DDP)-resistant cell line from human endometrial cancer cell line Ishikawa and to investigate its resistant mechanism to DDP. METHODS: A resistant endometrial cancer cell line ISH/DDP was established by gradually increasing dose of cisplatin and high-dose stimulation. The resistant index was estimated by 3-(4,5-dimethylthiazol-zyl)-5-(3-carboxymethoxyphenyl-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay. Cell growth curve, doubling time and cell cycle phase distribution were measured; drug-resistant protein of breast cancer resistance protein (BCRP), P-glycoprotein (P-gp) and glutathione-S-transferase-π (GST-π) were examined by immuocytochemistry. Results The DDP-resistant cell line ISH/DDP was established with the resistant index of 3.77. The proliferation of ISH/DDP got slow, doubling time prolonged, which were 40.1 hours, while it was 34.1 hours in Ishikawa (P<0.05); and the cell number of G0/G1 phase [(44.3±5.7)% and (39.0±10.7)%, P>0.05] and G2/M phase [(11.9±0.7)% and (5.7±2.4)%, P<0.05] decreased, while S-phase [(44.2±6.1)% and (55.3±8.4)%, P<0.05] increased compared with parent cells. The comprehensive score of the expression of BCRP in ISH/DDP was 16.3±2.0, while it was 13.4±1.5 in Ishikawa (P<0.05). The score of the expression of P-gp in ISH/DDP and Ishikawa were 15.5±1.2 and 16.1±1.0 (P>0.05), respectively. The score of the expression of GST-π in ISH/DDP and Ishikawa were 15.2±1.9 and 14.9±1.1 (P>0.05). CONCLUSION: ISH/DDP cell line showed a typical resistant phenotype and biological characteristics, which may be accounted for high BCRP expression.