Role of RANTES and its receptor in gastric cancer metastasis

This study examined the role of regulated upon activation normal T cell expressed and secreted(RANTES) and its receptor C-C chemokine receptor type 5(CCR5) in gastric cancer metastasis and the associated mechanism.The expression of RANTES and CCR5 was detected by using immunohistochemical staining and Western blotting in the gastric cancer tissues obtained from 60 gastric cancer patients with or without lymph node metastasis(n=30 in each).The results showed that the expression levels of RANTES and CCR5 were higher in gastric cancer with lymph node metastasis than in that without metastasis(P<0.05).The expression levels of RANTES in 30 lymph nodes with cancerous invasion were higher than in 30 normal lymph nodes(P<0.05).Chemotactic test revealed that the number of migrating gastric cancer cells(n=295.0±54.6) induced by the protein of cancer-invading lymph nodes was greater than that by the protein mixture from cancer-invading lymph nodes and RANTES antibody(n=42.5±11.6)(P<0.05).RT-PCR showed that the expression levels of the main Th1 cytokines(IL-2,γ-IFN) were lower in gastric cancer with lymph node metastasis(2.22±0.90,3.26±1.15 respectively) than in that without metastasis(3.07±1.67,4.77±1.52 respectively)(P<0.05),but the expression level of the main Th 2 cytokine(IL-10) was higher in gastric cancer with lymph nodes metastasis(6.06±2.04) than in that without metastasis(4.88±1.87)(P<0.05).It was concluded that RANTES and its receptor CCR5 may contribute to gastric cancer metastasis through influencing the balance of Th1/Th2.RANTES and CCR5 may become a marker of gastric cancer metastasis.     

Prognostic significance of MDR-1 P-glycoprotein expression in breast cancer

Objective: To investigate the expression of MDR-1 P-glycoprotein(MDR-1 Pgp) in breast cancer and analyze its correlation to the biological behavior and prognosis of the disease. Methods:The expression of MDR-1 Pgp was examined in 75 cases of breast cancer patients by using three different monoclonal antibodies(JSB1, C219 and C494) with S-P immunohistochemisty. These patients were followed up for 5 years, and the correlation between MDR-1 Pgp expression, survival rate and lymph metastasis was analyzed. Results: Positive detection of MDR-1 Pgp by JSB1, C219 and C494 in 75 cases of breast cancer was 86.7%, 48% and 85.3%, respectively. MDR-1 Pgp expression was not related to ages of patients (P > 0.05). JSB1-detected expression of MDR-1 Pgp was related to lymph node metastasis(P < 0.05); while C219 and C494 were not(P > 0.05). The patients with MDR-1 Pgp expression positively detected by either two of the three antibodies, had five-year survival rate that was significantly higher than those positively detected by all the three antibodies(P < 0.05). Conclusion:Three antibodies should be used simultaneously to detect MDR-1 Pgp expression in breast cancer. Positive MDR-1 Pgp expression in breast cancer detected by all the three antibodies may represent a poor prognosis; while positive MDR-1 Pgp detection by JSB1 and C494 is associated with lymph metastasis.     

Correlation between elevated FOXP3 expression and increased lymph node metastasis of gastric cancer

Background FOXP3 was thought to express in the T-cell lineage exclusively until recently when FOXP3 was shown to be expressed by cancer cells. It was indicated that FOXP3 may play a wider role in biology by endowing tumor cells with immune suppressive activity. However, researches between FOXP3 and lymph node metastasis of gastric cancer were relatively infrequent, so the present work was aimed to investigate the relationship between FOXP3 expression and lymph node metastasis in human gastric cancer.Methods A total of 122 gastric cancer patients were enrolled in this study, and gastric tumor specimens and lymph nodes were acquired. Thirty patients who had chronic superficial gastritis diagnosed by gastroscopy contemporaneously in the Peking University People＇s Hospital were chosen randomly as the control group. Immunohistochemistry was performed to evaluate FOXP3 expression. A survival analysis on the 122 patients was then performed. Then, NCI-N87cell lines were used to confirm FOXP3 expression in gastric carcinoma cells. Finally, evaluation of FOXP3 expression in gastric tumor and peritumor tissues in 12 patients were conducted using immunohistochemistry and Western blotting. A X2 test or Fisher＇s exact test （bilateral） was conducted to compare the percentage of positive percentage staining between groups. Kaplan-Meier analysis was performed for survival analysis.Results FOXP3 was expressed by gastric cancer cells and peritumor epithelial cells. FOXP3 expression was increased in primary tumors （58.2%） than that in control group （26.7%）. In the lymph-node metastasis group, the incidence of lymph node metastasis which was less than 60% had a significant upregulation of FOXP3 in primary tumors and lymph nodes.However, the frequency of FOXP3 expression had no relationship with survival.Conclusion FOXP3 probably has a relationship with lymph node metastasis of gastric cancer.     

Aidi Injection (艾迪注射液) Alters the Expression Profiles of MicroRNAs in Human Breast Cancer Cells

Objective: To investigate the effects of Aidi Injection (艾迪注射液 ADI) on the MicroRNAs (miRNA) expression profiles in human breast cancer cells and explore the potential targets of the cancer treatment. Methods: MCF-7 breast cancer cells were grown in RPMI 1640 medium supplemented with different concentrations of ADI. The inhibition of cell proliferation was measured by MTT assay. MCF-7 cells were treated by ADI with above 50% inhibiting concentration (IC50) for 48 h. The expression profiles of miRNA in ADI-treated and ADI-untreated MCF-7 cells were detected with miRNA microarray chips and the array data were verified by quantitative RT-PCR. MCF-7 cells were transiently transfected with miRNA mimics by liposome method. Potential mRNA targets were predicted by informatics analysis with TargetScan and PicTar software. Results: ADI significantly inhibited the proliferation of MCF-7 cells in a dose-dependent manner. The IC50 of ADI was 55.71 mg/mL after treatment for 48 h. The 60 mg/mL ADI was used as the therapeutic drug concentration. Microarray analysis identified 45 miRNAs that were up-regulated and 55 miRNAs that were down-regulated in response to ADI treatment. Many ADI-induced miRNAs were related to breast cancers. The microarray data were validated by qRT-PCR. Ectopic expression of 100 nmol/L mir-126 mimics significantly inhibited the proliferation of MCF-7 cells. The 12 potential target genes of mir-126 were predicted by both TargetScan and PicTar software. Conclusions: The miRNA may serve as therapeutic targets, and the modulation of miRNA expression is an important mechanism of ADI inhibiting breast cancer cell growth.     

Regulation of estrogen receptors α and β in human breast carcinoma by exogenous leptin in nude mouse xenograft model

Background It is essential to clarify the interactions of hormones during the progression of human breast cancer. This study examined the effects of exogenous human leptin on estrogen receptor （ER） α and β in human breast tumor tissue in a nude mouse xenograft model. Methods We created nude mice xenografts of MCF-7 human breast cancer cells, and randomly divided them into an experimental group and a control group. The mice in experimental group were injected subcutaneously around tumors with human leptin, while the control group were injected with the same dose of normal saline. A real-time RT-PCR assay was developed to quantify the mRNA of ERα, β in the tumor tissues. Western blotting analyses were used to assess the relative quantities of the ERα , β proteins. Results Leptin-treated xenografted nude mice were successfully established. The amount of ERa mRNA was significantly higher in the leptin group than in the control group （P 〈0.01）, while the amount of ERβ mRNA was significantly lower in the leptin group than in the control group （P 〈0.01）. Western blotting analyses revealed that the ERa protein level was significantly higher in the leptin group than in the control group （P 〈0.01）, while the ERβ protein level was significantly lower in the leptin group than in the control group （P 〈0.01）. Conclusions Nude mouse xenograft model can be safely and serviceably treated with human leptin by subcutaneous injections around tumor. ERα, β were both targets of leptin in breast cancer. Leptin can up-regulate the expression of ERa and down-regulate the expression of the ERβ in human breast tumor.     

Contribution of minute axillary lymph nodes to accurate staging for patients with breast cancer

Background Axillary lymph node metastasis is a very important metastatic pathway in breast cancer and its accurate detection is important for staging tumour and guiding therapy. However, neither the accuracy of routine detection of lymph node in surgical specimens nor the significance of minute lymph node with metastases in breast cancer is clear. A modified method for conveniently detecting minute lymph node in specimens of axillary dissections in patients with breast cancer was used to analyze their influence on staging breast cancer. Methods Lymph nodes in fresh, unfixed, specimens of axillary dissections from 127 cases of breast cancer were detected routinely. Then the axillary fatty tissues were cut into 1 cm thick pieces, soaked in Carnoy’s solution for 6 to 12 hours, taken out and put on a glass plate. Minute lymph nodes were detected by light of bottom lamp and examined by routine pathology. Results Lymph nodes (n= 2483, 19.6±8.0 per case) were found by routine method. A further 879 lymph nodes up to 6 mm (781 &lt; 3 mm, 6.9±5.3 per case, increasing mean to 26.5±9.7) were found from the axillary tissues after soaking in Carnoy’s solution. By detection of minute lymph nodes, the stages of lymph node metastasis in 7 cases were changed from pathological node (pN) stage pN(0) to pN(1) in 4 cases, from pN(1) to pN(2) in 2 and from pN(2) to pN(3) in 1. Conclusions The accurate staging of axillary lymph node metastasis can be obtained routinely with number of axillary lymph nodes in most cases of breast cancer. To avoid neglecting minute lymph nodes with metastases, small axillary nodes should be searched carefully in the cases of earlier breast cancer with no swollen axillary nodes. Treatment with Carnoy’s solution can expediently detect minute axillary nodes and improve the accurate staging of lymph nodes in breast cancer.     

Breast cancer associated fibroblasts promote MCF-7 invasion in vitro by secretion of HGF

This study was aimed to explore the influence of breast cancer associated fibroblasts (CAFs) in migration and invasion of breast cancer cell line MCF-7,and investigate whether hepatocyte growth factor (HGF) is involved in this process.Primary breast CAFs and their corresponding normal breast fi-broblasts (NFs) were obtained by collagenase digestion.On the basis of the co-culture,the migration and invasion capacity of MCF-7 cells was compared between CAFs and NFs by Transwell.The differ-ence in the HGF expression between them was detected by ELISA.The secretion of HGF was knocked down by using RNA interference technology in CAFs.Then the changes of migration and invasion ca-pacity of MCF-7 cells were investigated by Transwell.Eventually,we isolated high-purity CAFs and NFs,and the CAFs had a stronger ability in promoting MCF-7 migration and invasion than the NFs.ELISA results demonstrated that CAFs secreted higher HGF,and the capacity of MCF-7 migration and invasion was declined after knocking down the secretion of HGF in CAFs by RNA interference.It is suggested that CAFs can promote MCF-7 migration and invasion through HGF in vitro.     

Inhibitory Effects of Mild Hyperthermia plus Docetaxel Therapy on ER（＋/-） Breast Cancer Cells and Action Mechanisms

Summary： The purpose of this study was to verify that a combination of mild hyperthermia and do- cetaxel chemotherapy produces synergistic antitumor effects and to explore the action mechanisms of this treatment approach. The effects of docetaxel on the proliferation of cells from the estrogen receptor （ER）-positive human breast cancer cell line MCF-7 and the ER-negative human breast cancer cell line MDA-MB-453 were examined by 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide （MTT） assay, and effective experimental concentrations of docetaxel were determined. The effects of mild hy- perthermia plus docetaxel therapy on apoptosis rate in the MCF-7 and MDA-MB-453 human breast cancer cell lines were analyzed by using flow cytometry with Annexin-V fluorescein isothiocyanate （FITC）/propidium iodide （PI） staining. The effects of these combined treatments on cell cycle progres- sion in the MCF-7 and MDA-MB-453 human breast cancer cell lines were examined by using flow cy- tometry. The effects of these combined treatments on the expression of apoptosis-related proteins and proteins in the mitogen-activated protein kinase （MAPK） pathways were analyzed by using Western blotting. The effects of these combined treatments on the expression of the heat shock protein 70 （HSP70） and the multi-drug resistance （MDR） gene product P-glycoprotein （Pgp） were examined by using Western blotting. The results showed that the half-maximal inhibitory concentration （IC50） of do- cetaxel for MCF-7 and MDA-MB-453 cells was 19.57±1.12 and 21.64±2.31 gmol/L respectively. Mild hyperthermia with docetaxel therapy could increase apoptosis rate in the MCF-7 and MDA-MB-453 cells. Apoptosis rate in MCF-7 and MDA-MB-453 cells was increased from （23.66±3.59）% and （18.51±3.17）% in docetaxel treatment group to （47.12±6.73）% and （55.16±7.42）% in mild hyperthermia plus docetaxel group, indicating that the mild hyperthermia and docetaxel therapeutic approaches exhib- ited significant synergistic antitumor effects. Treatments of mild hyperthermia plus docetaxel induced G2/M cell cycle arrest in the MCF-7 and MDA-MB-453 cells. Western blotting demonstrated that pro- teins in the MAPK pathway were expressed at higher levels in docetaxel-treated cells following mild hypothermia than those in cells treated with docetaxel alone. As compared with blank control group, cells from the mild hyperthermia plus docetaxel group exhibited significantly decreased B-cell lym- phoma 2 （Bcl-2） protein expression but slightly increased Bcl-2-associated X protein （Bax） expression. Western blotting results revealed that HSP70 and Pgp expression levels were significantly increased following mild hypothermia. It was concluded that treatments of mild hyperthermia plus docetaxel in- hibited the proliferation of human breast cancer cells, promoted apoptosis of breast cancer cells, and produced synergistic antitumor effects.     

The value of 18-FDG-PET for diagnosing and evaluating lymph node metastasis in primary breast cancer

Objective： To analyze the result of 18F-2-deoxy-2-fluoro-D-glucose-positron emission tomography （FDG-PET） in suspicious primary breast cancer patients and to evaluate its value for the surgery therapy. Methods： Total 36 patients suspected of breast neoplasm were enrolled into the research. The result was compared with the pathology result. The rate of missed diagnosis, the rate of misdiagnosis, the sensitivity and specificity were calculated and analyzed. Results ：Compared with the pathology results, the misdiagnosis rate, the rate of missed diagnosis, the sensitivity and specificity of FDG-PET for breast cancer were 0%, 36.36%, 63.63% and 100%, respectively. To those who had a neoplasm no more than 2 cm in diameter, the rate of missed diagnosis was as high as 41.67%. To 33 breast cancer patients, the misdiagnosis rate, the rate of missed diagnosis, the sensitivity and specificity for lymph node metastasis were 18.75%, 41.18%, 58.82% and 81.25%, respectively. Conclusion：FDG-PET has a perfect specificity and a considerable sensitivity to the primary breast neoplasm and similar to the lymph node metastasis diagnosis. It is an ideal choice for those patients with suspected breast cancer but reluctantly to receive a vulnerarious examination.     

Inhibition of cell proliferation by siRNA targeting hPRLR in breast cancer MCF-7 cell line

Objective： To study the inhibition of proliferation of breast cancer by small interfering RNA（siRNA） targeting human prolactin （hPRLR） and the underlying mechanisms. Methods：The siRNA targeting hPRLR was chemically synthesized and transfected into MCF-7 cells, the expression of hPRLR was analyzed by real-time quantitive PCR, cell growth inhibition was measured with MTT assay, cell cycle of the transfected cells was examined by flow cytometry, meanwhile, expression of cyclin D1 was tested by semi-quantitative RT-PCR, Results：24 h after transfection with 100 nmol/L siRNA-PRLR, the expression of hPRLR mRNA was suppressed by 65%, cells in G1 phase increased, but cells in S phase decreased. Down regulated hPRLR expression exhibited significant inhibition in cell proliferation. And the expression of cyclin D 1 was down regulated. Conclusion：The results indicate that siRNA-hPRLR is a useful tool for silencing hPRLR expression and inhibiting cell proliferation in breast cancer MCF-7 cell line, and it may be a possible new approach for breast cancer gene therapy.     

miR-21 targets Fas ligand-mediated apoptosis in breast cancer cell line MCF-7

Over-expression of Fas ligand （FasL） on tumor cell surface can induce the apoptosis of spe- cific activated tumor infiltrating lymphocytes （TILs） via the Fas/FasL pathway, leading to the formation of a site of immune privilege surrounding the tumor mass for escaping immune surveillance and pro- moting tumor proliferation, invasion and metastasis. The blocking effect of miR-21 on FasL-mediated apoptosis in breast cancers was investigated in this study. The expression levels of miR-21 and FasL in human breast carcinoma cell lines were detected by using RT-PCR and Western blotting. FasL as a tar- get gene of miR-21 was identified by Luciferase assay. The apoptosis of Jurkat T lymphocytes induced by MCF-7 cells was determined by flow cytometry. It was found that in four human breast cancer cell lines, FasL expression level in MCF-7 cells was the highest, while miR-21 was down-regulated the most notably. After miR-21 expression in MCF-7 cells was up-regulated, FasL was identified as a target gene of miR-21. When the effector/target （E/T） ratio of MCF-7 cells and Jurkat cells was 10：1, 5：1 and 1：1, the inhibitory rate of apoptosis of Jurkat T lymphocytes induced by MCF-7 cells was 95.81%, 93.16% and 91.94%, respectively. It is suggested that in breast cancers miR-21 expression is negatively associ- ated with FasL expression, and FasL is a target gene of miR-21, miR-21 targeting and regulating FasL-mediated apoptosis will bring us the possibility of a new tumor immunotherapy via breaking tu- mor immune privilege.     

EXPRESSION AND SIGNIFICANCE OF SURVIVIN mRNA IN LUNG CANCER TISSUE MICROARRAY DETECTED BY FISH

Objective To investigate the expression of Survivin mRNA in lung cancer tissue microarray (TMA) by fluorescence in situ hybridization (FISH) method, and determine the role and significance of it in lung cancer genesis and progress. Methods The expression of Survivin mRNA was detected by FISH method and TMA technology. Fifty-four cases of lung cancer and 10 cases of normal lung tissue were examined. Results Survivin mRNA was expressed in 66.7% (36/54) of lung cancer; the positive ratio of lung cancer was significantly higher than that of normal lung tissue (0/10; x2= 15.238, P ＜ 0.05). The positive ratio of Survivin mRNA was significantly higher in poor differentiated cancer (20/24, 83.3%) than moderate and well differentiated cancer (16/30, 53.3%; x2= 5.40, P ＜0.05). The positive ratio of Survivin mRNA was significantly higher in group with lymph node metastasis (27/32, 84.4%) than without lymph node metastasis (9/22, 40.9%; x2= 11.084, P ＜ 0.05). The positive ratio of Survivin mRNA was significantly higher in stage Ⅲ-Ⅳ(12/13, 92.3%) than stage Ⅰ - Ⅱ (24/41, 58.5%; x2= 5.066, P ＜ 0.05). Conclusion Survivin mRNA highly expresses in lung cancer, which is related to the progress and malignant behavior. Survivin may play a promoting role in lung cancer genesis and progress and provide a basis for estimating prognosis and treatment.     

TNF-alpha-induced metastasis gene changes in MCF-7 cells

Objective: Studies have shown that TNF-αsecreted by tumor cells and macrophages infiltrated into the tumor microenvironment might promote the metastasis of a variety of malignant cancers, including breast cancer. The present study was designed to detect global metastasis-related gene expression changes of MCF-7 cells treated by low dose TNF-α and to further explore the mechanisms by which TNF-αcontributes to metastasis. Methods: MCF-7 cells were cultured and treated with low dose TNF-α(20 ng/ml). cDNA array analysis was applied to detect the metastasis related gene expressions. Results: A total of 36 gene expressions were significantly regulated by TNF-α. Functional analysis indicates that the altered genes belong to different functional group. Most of the genes changed may promote the metastasis of MCF-7 cells while the others may inhibit metastasis. The changes observed in gene expression following TNF-αwere somewhat time dependent. Conclusion: TNF-αcan enhance the invasive ability of MCF-7 cells, partly by regulating a series of metastasis related genes, and these genes may take part in every step of metastasis. Some of the genes deserve further study.     

Proximal gastric cancer: lymph node metastatic patterns according to different T stages dictate surgical approach

Background As a common form of gastric cancer migration,lymph node metastasis largely affects the surgical treatment and prognosis of gastric cancer.Surgery is the fundamental curative option for gastric cancer that varies depending on different stages.The study aimed to compare the clinicopathological characteristics and lymph node metastatic patterns in patients of proximal gastric cancer with different T stages and investigate a reasonable radical gastrectomy approach in terms of the range of lymphadenectomy for proximal gastric cancer.Methods In our retrospective study,the data of 328 patients of proximal gastric cancer with different T stages were analyzed.By comparing the differences of lymph node metastatic rate and ratio,we investigated the clinicopathological characteristics and metastatic patterns of lymph nodes.Also,we were especially interested in the differences in survival rates between patients with and without No.5 and 6 group metastasis with the same TNM stage.Results The overall lymph node metastatic rate and ratio of advanced proximal gastric cancer were 73.4％ and 23.3％,respectively.The tumors of different T stages were statistically significant in size and differentiation degree （P ＜0.05）,multivariate analysis showed that the depth of tumor invasion was an independent risk factor for lymph node metastasis in proximal gastric cancer （RR,12.025; 95％ CI,2.326 to 62.157; P=0.003）.The overall survival rate of patients with No.5,6 group lymph node metastasis and those without was significantly different,but the differences in survival rates between patients with and without No.5 and 6 group metastasis with the same TNM stage were not statistically significant.Conclusions Different T stages in proximal gastric cancer showed different patterns and characteristics of lymph node metastasis.D2 lymphadenectomy in patients with early gastric cancer had little survival benefit because metastasis to level 2 nodes was rare.Therefore the range of the lymph node dissection in radical gastrectomy     

CLINICOPATHOLOGICAL SIGNIFICANCE OF PTEN AND CASPASE-3 EXPRESSIONS IN BREAST CANCER

Objective To investigate the expressions of PTEN and Caspase-3 proteins in human breast carcinoma, and to evaluate their clinicopathological implications during the tumorigenesis and progression of breast cancer. Methods The expressions of PTEN and Caspase-3 proteins in 95 cases of breast cancer and 15 cases of benign breast diseases were investigated immunohistochemically. Correlations between the expression of PTEN protein, Caspase-3 protein, and clinicopathological features of breast cancers were analyzed. Results The loss expression rate of PTEN protein in tumor tissues was significantly higher than that in benign breast diseases （33.7% vs. 0, P 〈 0.01 ）. Analysis of the clinicopathological features showed that PTEN expression level was negatively correlated with TNM stage, histological grade, axillary lymph node status, recurrence, and metas- tasis （ P 〈 0. 05 ）. The positive expression level of Caspase-3 was negatively correlated with TNM stage （ P 〈 0. 01 ）, but not related with histological grade, axillary lymph node status, recurrence, or metastasis （ P 〉 0.05 ）. In addition, the expression of PTEN protein had significantly positive correlation with the expression of Caspase-3 protein in breast cancer （P 〈 0. 01 ）. Conclusion The combination detection of PTEN and Caspase-3 may serve as an important index to estimate the pathobiological behavior and prognosis of breast cancer.     

Targeting of p38 Mitogen-activated Protein Kinases to Early Growth Response gene 1 （EGR-1） in the Human Paclitaxel-resistance Ovarian Carcinoma Cells

To investigate the relationship between the expression of early growth response gene 1 (EGR-1) and p38MAPK pathway in the paclitaxel resistance of ovarian carcinoma cells, the effect of p38MAPK inhibitor SB203580 on cell apoptosis was examined by using Hoechst 33258 staining. The intracellular Rh123 (Rhodamine 123) accumulation was detected by the flow cytometry (FCM). The 50% inhibition concentration (IC50) of paclitaxel for A2780/Taxol cells was determined by MTT method. Electrophoretic motility shift assay (EMSA) was employed to examine the EGR-1DNA binding activity. MDR1 and EGR-1 mRNA were assessed by RT-PCR. The expressed of p-gp, phos- phorylated p53 and p38 were detected by Western blotting. SB203580 could remarkably promote the apoptosis of A2780/Taxol cells, and the cell apoptosis was in a time-dependent manner. Cellular Rh123 accumulation was increased, and the IC50 of paclitaxel for A2780/Taxol cells was decreased significantly. A2780/Taxol cell line after SB203580 treatment was shown to have a significantly higher level of EGR-1 DNA binding activity. SB203580 down-regulated the activity of p38MAPK pathway, but up-regulated EGR-1 expression. SB203580 significantly increased the level of cellular phosphorylated p53 protein, but decreased the p-gp protein level and MDR1 mRNA level in A2780/Taxol cells. There existed a close relationship between p38MAPK pathway and the paclitaxel resistance of ovarian carcinoma cells. The expression of EGR-1 mediated by p38MAPK pathway plays a critical role in paclitaxel resistance of ovarian carcinoma cells.