Expression of beta-tubulin isotypes in human ovarian carcinoma xenografts and in a sub-panel of human cancer cell lines from the NCI-Anticancer Drug Screen: correlation with sensitivity to microtubule active agents.

Paclitaxel resistance has been associated with overexpression of P-glycoprotein and alterations involving tubulin. To investigate the clinical relevance of these in vitro resistance mechanisms, we established 12 human ovarian carcinoma xenografts, using samples from patients before the start of therapy or after paclitaxel treatment. These xenografts showed a wide range of sensitivity to paclitaxel, and in 4 of them, very low levels of multidrug resistance-1 expression were detected. Using quantitative PCR and human specific primers, the expression of five beta-tubulin isotypes was determined. HM40 was the predominant, accounting for 84.7-98.7% of all tubulin; expression of the other four isotypes (Hbeta9, Hbeta4, H5beta, and Hbeta2) was also detected but at lower levels. No correlation could be demonstrated between isotype expression and paclitaxel sensitivity in these 12 xenografts. A similar pattern of beta-tubulin isotype expression was observed in a subset of cell lines from the National Cancer Institute-Anticancer Drug Screen. In these cell lines, however, a significant correlation between increased expression of Hbeta4 isotype and resistance to paclitaxel was found. Taken together, these results suggest that altered expression of specific beta-tubulin isotypes may not play a significant role in paclitaxel sensitivity in vivo and argue against a possible significance in a clinical setting.

Wild-type p53 marginally induces endogenous MDR-1 mRNA without causing a measurable drug resistance in human cancer cells.

The notion that wt p53 downregulates MDR-1 links p53 mutations to multidrug resistant phenotype. Alternatively, it has been envisioned that wt p53 protects cells against DNA damaging drugs by inducing MDR-1. Opposing conclusions on the relationship between MDR-1 and p53 have been predominantly based on the effects of p53 on MDR-1 promoter-constructs. We found that introduction of wt p53 slightly induced MDR-1 mRNA in three cell lines having endogenous mt p53. Wt p53-mediated induction of endogenous MDR-1 may represent a rudiment of cellular protection against toxic compounds earlier in evolution. Marked induction of p21WAF1/CIP1 (p21) mRNA was observed in all cell lines; and lower levels of wt p53 were required to induce p21 than MDR-1. Pgp was undetectable and wt p53 did not increase resistance to an MDR-1 substrate, suggesting the changes in MDR-1 mRNA may be functionally insignificant. Unlike endogenous MDR-1, the expression of an MDR-1 promoter (-434/+147 fragment) - luciferase construct was unchanged or even inhibited by wt p53 that may be secondary to wt p53-mediated cytotoxicity. Thus, partial promoter constructs may not accurately represent endogenous MDR-1.

IDN5109, a taxane with oral bioavailability and potent antitumor activity.

IDN5109 is a new taxane, derived from 14beta-hydroxy-10-deacetylbaccatin III, selected for its lack of cross-resistance in tumor cell lines expressing the multidrug resistant phenotype. Because, unlike paclitaxel, IDN5109 is a poor substrate for P-glycoprotein, we hypothesized that IDN5109 given p.o. could improve bioavailability compared with paclitaxel. Here, we studied the p.o. and i.v. pharmacokinetics of IDN5109 together with its antitumor activity. Using a high-performance liquid chromatography method, the bioavailability of IDN5109 was determined to be 48% after oral delivery. IDN5109 given p.o. was highly active against the two human ovarian carcinoma xenografts 1A9 and HOC18 (90-100% tumor regressions) and showed significant activity on the paclitaxel-resistant MNB-PTX1 xenograft (10% tumor regressions). The p.o. administration was as active as the i.v. route at doses reflecting the pharmacokinetic data. IDN5109 is the first taxane with good oral bioavailability and potent antitumor activity and represents a potential candidate for clinical investigation.

Molecular characterisation of a panel of human ovarian carcinoma xenografts.

In a panel of 16 human ovarian tumours transplanted in nude mice, the expression of genes involved in cell cycle regulation and in response to drug treatment were characterised. In the 16 tumours analysed we could not detect overexpression of Erb-B2 oncogene while expression of MDR1 mRNA was not detected in 11/15 samples and was low in 4/15 tumours. Only three tumours had mutations in the p53 gene exons 5-8 and one of these mutations did not result in any amino acid alteration. The levels of mRNA for cyclins A, D1 and E were heterogeneous with some tumours expressing high levels and others not expressing them at all. The same was found for the cyclin dependent kinases (CDK) CDK2 and CDK4 and for CDK inhibitors p21/WAF1, p27/KIP1 and p16/CDKN2. Two genes belonging to the nucleotide excision repair, ERCC1 and ERCC3 were detectable in all the samples examined, as were the genes MGMT and MAG, also involved in DNA repair. The data indicate a heterogeneity in the expression of genes considered to be involved in the cellular responses to cytotoxic drug treatment and indicate the possibility of using these tumour models to test specifically molecules with a defined mechanism of action.

Ecteinascidin-743, a new marine natural product with potent antitumor activity on human ovarian carcinoma xenografts.

The antitumor activity of ecteinascidin (ET)-743, a novel marine natural product, was evaluated against a panel of human ovarian carcinoma xenografts characterized by different malignant behaviors and drug responsiveness in nude mice. These tumor models included three xenografts transplanted s.c. (HOC18, HOC22-S, and MNB-PTX-1) into nude mice, representing different levels of sensitivity to cisplatinum (DDP), which was used as reference drug for ovarian carcinoma, and two other xenografts (HOC22 and HOC8), which are highly malignant in the peritoneal cavity of nude mice, representing the growth pattern of this neoplasm. At the maximum tolerated dose of 0.2 mg/kg using an intermittent schedule of one i.v. injection every 4 days, ET-743 was highly active against HOC22-S (sensitive to DDP), inducing long-lasting, complete regressions, and against HOC18 (marginally sensitive to DDP), inducing partial tumor regressions. Moreover, significant growth delay was observed in mice bearing late-stage HOC18 tumor (400-mg tumor weight; nonresponsive to DDP). ET-743, however, was not active against MNB-PTX-1, a tumor that is highly resistant to chemotherapy, including DDP. In the i.p. ovarian carcinoma xenograft model, ET-743 at the maximum tolerated dose induced complete tumor remissions in all mice bearing HOC22 tumor, with 25% histopathologically confirmed cures, and produced marginal tumor growth delay against HOC8. These results indicate that ET-743 is a potent drug against ovarian carcinoma xenografts, being equally as active or more efficacious than DDP in the same tumor line. Our findings with human ovarian carcinoma xenografts justify clinical assessment of this drug with this tumor target.

Batimastat, a synthetic inhibitor of matrix metalloproteinases, potentiates the antitumor activity of cisplatin in ovarian carcinoma xenografts.

Batimastat (also known as BB-94) is a synthetic matrix metalloproteinase inhibitor that has shown antineoplastic and antiangiogenic activity in various tumor models. In this study, two human ovarian carcinoma (HOC) xenografts (HOC22 and HOC8) were used to investigate the effect of batimastat on the antineoplastic activity of cisplatin. Both xenografts produced ascites and solid lesions in the peritoneal cavity of nude mice. HOC cells were inoculated i.p. in nude mice, and treatment was started at different stages of the disease. Batimastat was administered alone or concurrently with or subsequent to cisplatin therapy. In all of the protocols, the response of HOC xenografts was confirmed by cytological analysis of ascites and histological examination of the organs in the peritoneal cavity. Treatment of nude mice bearing early-stage (3 days after tumor implantation) HOC22 or HOC8 with cisplatin or batimastat alone delayed tumor growth and increased the survival time of the mice, although all animals eventually died. In contrast, treatment with batimastat (60 mg/kg i.p. every other day, for a total of eight injections) concomitantly with cisplatin (4 mg/kg i.v., every 7 days for a total of three injections) completely prevented growth and spread of both xenografts, and all animals were alive and healthy on day 200. The potentiation of cisplatin's activity by batimastat was dose dependent and was observed in the treatment of both advanced (7 days after tumor inoculation) and late-stage (20 days after inoculation) tumor. The administration of batimastat following cisplatin therapy also led to significant improvement in the survival of mice compared to treatment with cisplatin alone. These results suggest a potentiation of the antineoplastic activity of cisplatin by batimastat and support the use of the two agents in combination in the treatment of ovarian cancer patients.

Paclitaxel (Taxol(R)) inhibits motility of paclitaxel-resistant human ovarian carcinoma cells.

The effect of paclitaxel on the adhesive and motility properties of human ovarian carcinoma cell lines was investigated. Paclitaxel significantly inhibited the motility of OVCAR 5, SK-OV-3, and HOC-1OTC ovarian carcinoma cell lines (IC50 = 2.1 x 10(-8), 2 x 10(-9), and 1.9 x 10(-8) m, respectively) but did not affect the adhesion of these cells to the subendothelial matrix. The association between inhibition of motility and cytotoxic activity was investigated using an A2780 subclone (1A9) and three paclitaxel-resistant variants (designated 1A9/PTX22, 1A9/PTX10, and 1A9/PTX18). Although paclitaxel did not significantly affect the adhesion to subendothelial matrix of the sublines, it completely inhibited their migration. Inhibition of migration was similar in 1A9 cells and the resistant sublines, with an IC50 of 1 x 10(-8) for 1A9 cells and 5.4 x 10(-9), 1.1 x 10(-8), and 5.2 x 10(-9) m for 1A9/PTX22, 1A9/PTX10, and 1A9/PTX18, respectively. Paclitaxel inhibited motility induced by soluble attractant (chemotaxis) and immobilized attractant (haptotaxis). Inhibition of cell motility occurred in the absence of an antiproliferative effect, because higher concentrations of paclitaxel were required to inhibit tumor cell proliferation (IC50 = 1.9 x 10(-7) and 4.6 x 10(-6), 1 x 10(-5), and 3.1 x 10(-6) m for 1A9 and 1A9/PTX22, 1A9/PTX10, and 1A9/PTX18, respectively). These data show that paclitaxel is a potent inhibitor of ovarian carcinoma cell motility and that this activity is independent of its cytotoxic activity.

Comparison of paclitaxel and docetaxel activity on human ovarian carcinoma xenografts.

The antitumour activity of paclitaxel (NSC 125973) and docetaxel (RP 56976, NSC 628503) was evaluated and compared against human ovarian carcinoma (HOC) xenografts in nude mice. Paclitaxel and docetaxel were given intravenously (i.v.) at a dose range of 16.6-34.5 mg/kg, once every 4 days for three consecutive doses to nude mice with HOC xenografts, transplanted subcutaneously (s.c.) (HOC18 and HOC22-S) or intraperitoneally (i.p.) (HOC8 and HOC22). Paclitaxel and docetaxel, at the highest dosage, induced complete tumour regression in 80-100% and 67% of mice bearing HOC22-S and HOC18 s.c., respectively. Both drugs cured 100% of mice bearing early stage HOC22 tumour in the peritoneal cavity, while treatment at an advanced stage significantly increased the survival time of all the mice. Both induced a 57% cure rate in mice bearing HOC8 in the peritoneal cavity. Paclitaxel and docetaxel were more effective than cisplatin (4 mg/kg, same dosing regime as above) used as a reference compound. These findings indicate that paclitaxel and docetaxel were highly active on four HOC xenograft models. No significant difference between them was detected in ovarian cancer xenografts.

Soluble intercellular adhesion molecule-1 (ICAM-1) is released into the serum and ascites of human ovarian carcinoma patients and in nude mice bearing tumour xenografts.

We have demonstrated that patients with ovarian carcinoma have higher levels of soluble intercellular adhesion molecule-1 (ICAM-1) in their serum and ascitic fluids than serum from normal individuals and non-neoplastic gynaecological disease or ascites from patients with cirrhosis. In order to investigate the source of the ICAM-1, and to study the mechanisms which regulate ICAM-1 release in ovarian carcinoma, we have employed the nude mouse model system. Three different human ovarian carcinoma (HOC) cell lines were grown as ascitic tumours in the peritoneal cavity of nude mice. HOC xenografts harvested from nude mice expressed comparable levels of ICAM-1 on their cell surface. Human ICAM-1 was detected, with a species-specific ELISA, in serum and ascitic fluid of tumour-bearing mice, confirming that the tumours were the source of the ICAM-1. The three HOC xenografts showed different levels of ICAM-1 release, but within each xenograft model the level of ICAM-1 in serum and ascitic fluid correlated with the tumour burden. The level of ICAM-1 released by the HOC xenografts could be increased by in vivo treatment with interferon gamma (IFN-gamma). Interleukin 1 (IL-1), tumour necrosis factor (TNF) and IFN gamma increased the cell surface expression of ICAM-1 and caused the release of soluble ICAM-1 from HOC cells established in vitro. The nude mouse provides a useful system in which to study the effects of modulating ICAM-1 release on the progression of ovarian carcinoma and suggests that measuring ICAM-1 levels in the blood or ascites of patients may provide an indication of tumour burden.

A ligand-free, soluble urokinase receptor is present in the ascitic fluid from patients with ovarian cancer.

We have identified a soluble form of the human urokinase plasminogen activator (uPA) receptor (uPAR) in the ascitic fluids from patients with ovarian cancer. After purification of uPAR from the ascitic fluids by ligand-affinity chromatography (pro-uPA Sepharose), the uPAR was initially identified by cross-linking to a radiolabeled amino-terminal fragment of human uPA. The uPAR purified from the ascitic fluid has no bound ligand (uPA), as similar amounts can be purified by ligand-affinity chromatography as by immuno-affinity chromatography. uPAR from ascitic fluids partitions in the water phase after a temperature-dependent phase separation of a detergent extract. It therefore lacks at least the lipid moiety of the glycophospholipid anchor present in cellular-bound uPARs. It is highly glycosylated and the deglycosylated form has the same electrophoretic mobility as previously characterized cellular uPAR from other sources. The immunoreactivity of the purified uPAR from the ascitic fluid is indistinguishable from that of characterized uPAR, demonstrated by Western blotting with three different anti-uPAR monoclonal antibodies. The uPAR was found in 11 of 11 ascitic fluids from patients with ovarian cancer and in elevated amounts in the plasma from 2 of 3 patients. The concentration of soluble uPAR in the ascitic fluid was estimated to range between 1 and 10 ng/ml. Human soluble uPAR, derived from the tumor cells, was also found in the ascitic fluid and serum from nude mice xenografted intraperitoneally with three different human ovarian carcinomas.

Antitumor activity of taxol (NSC-125973) in human ovarian carcinomas growing in the peritoneal cavity of nude mice.

BACKGROUND: The unique mechanism of action of taxol (NSC-125973) as microtubule stabilizing agent and its potential activity in clinical trials have generated considerable interest in the development of this agent. As taxol was reported to be active on advanced and refractory ovarian carcinomas we focused our studies on the xenograft model of human ovarian carcinoma that develops ascites and tumor dissemination in the peritoneal cavity of nude mice. METHODS: The antitumor activity of taxol was evaluated on two human ovarian carcinoma xenografts (HOC8 and HOC22) transplanted i.p. in nude mice. Drug was given i.v. at doses of 20-34.5 mg/kg every four days three times (Q4 x 3) and the increment of life span (%ILS) was evaluated. Cisplatin at the dosage of 4mg/kg, Q4 x 3 was used as reference drug in each experiment. RESULTS: Taxol given at doses of 20 mg/kg and 34.5 mg/kg to early-stage HOC22 (treatment starting 3 days after tumor transplant) cured all the mice, while the same dose regimens given to advanced HOC22 (treatment starting 14 days after tumor transplant) significantly prolonged the survival time of the mice (ILS = 197% and 300%). Taxol given 3 days after HOC8 transplant significantly prolonged the survival time of tumor-bearing nude mice, inducing complete responses in 50% and 25% of mice receiving, respectively, 34.5 mg/kg/injection and 20 mg/kg/injection. On both ovarian carcinoma xenografts taxol was more active than equitoxic doses of the reference drug cisplatin. CONCLUSIONS: The therapeutic activity against ovarian carcinoma xenografts supports the potential of taxol in the treatment of this neoplasia and forms the basis for future investigations aimed at optimizing the therapeutic activity of taxol given alone or in combination with other drugs.