The drug resistance-related protein LRP is the human major vault protein.

Multidrug-resistant cancer cells frequently overexpress the 110-kD LRP protein (originally named Lung Resistance-related Protein). LRP overexpression has been found to predict a poor response to chemotherapy in acute myeloid leukaemia and ovarian carcinoma. We describe the cloning and chromosome localization of the gene coding for this novel protein. The deduced LRP amino acid sequence shows 87.7% identity with the 104-kD rat major vault protein. Vaults are multi-subunit structures that may be involved in nucleo-cytoplasmic transport. The LRP gene is located on chromosome 16, close to the genes coding for multidrug resistance-associated protein and protein kinase C-beta, and may mediate drug resistance, perhaps via a transport process.

Preoperative [18F] FDG-PET after chemotherapy in locally advanced breast cancer: prognostic value as compared with histopathology.

BACKGROUND: Established prognosis-based criteria determine the need for further treatment after primary surgery for breast cancer. Such criteria are lacking after neo-adjuvant chemotherapy. We determine the prognostic value of preoperative [(18)F]-2-fluoro-2-deoxy-D-glucose-positron emission tomography ((18)FDG-PET) after chemotherapy in locally advanced breast cancer (LABC), both as independent indicator and as add-on to postoperative histopathology. PATIENTS AND METHODS: Preoperative PET was carried out in 40 LABC patients. Two expert readers assessed residual (18)FDG uptake in the primary tumor. At histopathological examination of the surgical specimen, chemotherapy response was graded using the Honkoop criteria. Cox proportional hazards analysis was used to determine prognostic relevance of PET and histopathology. RESULTS: Median follow-up was 60 months (range 15-94), during which 13 patients had recurrent disease, eight of whom died. (18)FDG uptake in the primary tumor was inversely related with disease-free survival (DFS) [hazard ratio (HR) 4.09; 95% confidence interval (CI) 1.26-13.31; P = 0.02] and this was superior to histopathology (HR 2.52; 95% CI 0.77-8.23; P = 0.13). Observer agreement of PET was excellent (intraclass correlation coefficient 0.88). Multivariate Cox regression revealed no added value of histopathology versus PET results. CONCLUSION: (18)FDG uptake in the primary tumor at PET was inversely associated with DFS and may help to guide adjuvant therapy.

[Osteoporosis in patients under treatment for cancer and the possibilities for prevention and treatment]. / Osteoporose bij patiënten die worden behandeld wegens kanker en de mogelijkheden voor preventie en behandeling.

The treatment of cancer can have a negative influence on bone metabolism. This can result in the development of early osteoporosis or the aggravation of existing osteoporosis, with an increased risk of fractures. Depending on the duration and type of cancer therapy, prophylactic or therapeutic measures against osteoporosis may become necessary. The risk of osteoporosis may be assessed by screening with osteodensitometry, among other methods. Effective treatment is possible, for example with bisphosphonates.

Pharmacology of the paclitaxel-cisplatin, gemcitabine-cisplatin, and paclitaxel-gemcitabine combinations in patients with advanced non-small cell lung cancer.

PURPOSE: To compare the pharmacology of the paclitaxel-cisplatin, gemcitabine-cisplatin and paclitaxel-gemcitabine combinations in patients with advanced non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: Twenty-four chemo-naive patients with advanced NSCLC were randomized to receive one of the three regimens. Plasma pharmacokinetics and pharmacologic parameters in mononuclear cells were compared and related to toxicity and efficacy. RESULTS: Pharmacological parameters of gemcitabine and cisplatin were not influenced by the combination with one of the other agents, while the paclitaxel clearance was significantly lower for the combination with cisplatin as compared to gemcitabine (P=0.024). The percentage decrease in platelets was significantly higher for the gemcitabine combinations (P=0.004) and related to the dFdCTP-Cmax (P=0.030). Pharmacologic parameters were not related to response or survival. CONCLUSIONS: Gemcitabine and cisplatin pharmacology were not influenced by the combination with one of the other agents, while paclitaxel has a lower clearance in combination with cisplatin as compared to gemcitabine.

Mechanism of action of antitumor drug etoposide: a review.

Metabolism studies of the antitumor drug etoposide show the formation of metabolites in the lactone ring, which are probably not important for the drug's mechanism of action, and oxidative transformations in the dimethoxyphenol ring (E ring), which lead to products that can cause DNA damage and may play a role in the drug's mechanism of action. The cytotoxicity of etoposide is caused by the induction of DNA damage. The occurrence of the DNA lesions can be explained by the capacity of the drug to interfere with the scission-reunion reaction of mammalian topoisomerase II by stabilizing a cleavable complex.

Reversal of 5-fluorouracil-induced myelosuppression by prolonged administration of high-dose uridine.

The effect of high-dose uridine on 5-fluorouracil (5-FU)-induced toxicity was investigated. Nine patients were treated weekly with 5-FU at increasing dosages. Five patients developed dose-limiting leukopenia, and four patients developed thrombocytopenia. At dose-limiting toxicity, 5-FU treatment was repeated and followed after 3 hours by intermittent iv infusion of uridine (2 g/m2 per hr) during 72 hours. Leukopenia was reversed for several weeks but thrombocytopenia was not. Side effects consisted of mild rises in body temperature. The pharmacokinetics of uridine were similar to those observed with single-agent uridine. Our data indicate that high-dose uridine can reduce the severity of 5-FU-induced myelosuppression.

Effects of recombinant human granulocyte-macrophage colony-stimulating factor on myelosuppression induced by multiple cycles of high-dose chemotherapy in patients with advanced breast cancer.

In this study, 18 patients with advanced breast cancer were treated with multiple cycles of doxorubicin (75 or 90 mg/m2) plus cyclophosphamide (750 or 1000 mg/m2) every 21 days. Granulocyte-macrophage colony-stimulating factor (GM-CSF) (250 micrograms/m2 per day) was administered by continuous infusion during 10 days (days 2-12), starting in the first or second cycle of chemotherapy. Sixteen (89%) of 18 patients (95% confidence interval, 65%-99%) achieved an objective remission, five (28%) of which were complete. The median duration of response was 7 months. When GM-CSF was used for the first time, it had an effect on the kinetics of all blood cells, including neutrophils, lymphocytes, thrombocytes, and reticulocytes. However, in subsequent cycles of chemotherapy, the stimulatory effect of GM-CSF on hematopoiesis was substantially diminished. World Health Organization grade 3 and 4 neutropenia and thrombocytopenia necessitated dose reductions of doxorubicin and cyclophosphamide from cycle 2 onward in all patients treated with the highest dose. Side effects of GM-CSF included fever, general weakness, and hypotension. These toxic effects mimicked sepsis, and hospital admission for treatment with intravenous antibiotics was required for 73 days in 61 cycles of chemotherapy that included GM-CSF. Dose-intensive chemotherapy produced a high response rate in patients with advanced breast cancer. However, GM-CSF administered from day 2 to day 12 at a dose of 250 micrograms/m2.

Clinical and pharmacologic study of orally administered uridine.

Effects of oral administrations of uridine were investigated in a study of six healthy volunteer control subjects and nine patients with metastatic colorectal cancer. Oral uridine was studied as single-dose administrations at doses escalating from 0.3 to 12 g/m2 and as multiple-dose administrations every 6 hours for 3 days at doses from 5 to 10 g/m2. The maximum tolerated dose (MTD) was 10 to 12 g/m2 for a single dose of uridine and 5 g/m2 for the multiple-dose regimen. Diarrhea was the dose-limiting toxic effect. Single-dose oral uridine resulted in an increase in plasma uridine concentrations in the range of 60 to 80 microM after doses of 8 to 12 g/m2. At these doses, bioavailability of oral uridine ranged from 5.8% to 9.9%. At the MTD of 5 g/m2 in the multiple-dose uridine schedule, steady-state plasma uridine levels of approximately 50 microM were achieved. Further studies should explore the role of oral uridine in the modulation of the toxicity of fluorouracil.

Human IgM monoclonal antibody 16.88: pharmacokinetics and immunogenicity in colorectal cancer patients.

Twenty colorectal cancer patients were given an intravenous injection of human IgM monoclonal antibody (MAb) 16.88 (8 mg) conjugated to 131I for tumor localization. After a 2-week interval, a second injection with 200, 500, or 1000 mg of unlabeled antibody added was given to groups of five patients each. at the end of the 2-hour infusion, 66% of the radioactivity remained in the circulation. Blood clearance of the 131I-labeled MAb 16.88 was biphasic with a mean half-life (T1/2 alpha) of 12 hours and T1/2 beta of 45 hours. Clearance rate was 0.09 L/hour. More than 90% of the 131I in serum was protein bound, with an immunoreactive fraction of 80% in the first 48 hours. Size exclusion chromatography indicated no degradation products other than 131I in serum and urine. The urinary excretion rate of 131I increased to 1.5% of the dose per hour at 24 hours, with 50% of the dose excreted in 34 hours. The pharmacokinetic profile of 131I-labeled MAb 16.88 was neither influenced by the total protein dose of antibody administered nor affected by specific uptake in tumor tissue in individual patients, as determined on early immunoscintigrams. The larger antibody doses showed a slightly slower excretion of 131I. The assays applied to determine immunogenicity were enzyme-linked immunosorbent assay, radioimmunoassay, and the dot-blot assay. They had sensitivities ranging from 5 ng/mL to 0.5 micrograms/mL for goat or rabbit antihuman IgM. The assays did not reveal antihuman antibody responses.

Quantitative determination of factors contributing to doxorubicin resistance in multidrug-resistant cells.

There is a large discrepancy between the changes in drug accumulation and the changes in drug cytotoxicity that accompany development of anthracycline resistance in multidrug-resistant cells. In our study, a quantitative relationship has been established between reversal of multidrug resistance by resistance modifiers and a concomitant decrease in intracellular levels of doxorubicin measured at equitoxic concentrations (IC50) in CHRC5 and 2780AD multidrug-resistant cells. (IC50 = concentration required for 50% growth inhibition.) We have demonstrated that resistance modifiers like verapamil and Ro 11-2933/001 act by increasing the effectiveness of intracellular doxorubicin, apparently by inducing redistribution of the drug from the cytoplasm to the nucleus of a multidrug-resistant cell, as shown by quantitative fluorescence microscopy. At complete reversal of resistance, as measured directly or inferred by extrapolation, the amount of intracellular doxorubicin at the IC50 as well as the ratio of nuclear doxorubicin to cytoplasmic doxorubicin were the same as those in sensitive cells. These results offer an explanation for the frequently observed discrepancies between drug accumulation and cytotoxicity and also show quantitatively that a decrease in drug accumulation and a change in intracellular drug distribution together are the only determinants of doxorubicin resistance in the multidrug-resistant cells studied.

Levels of hypoxia-inducible factor-1 alpha during breast carcinogenesis.

BACKGROUND: Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that regulates gene expression in critical pathways involved in tumor growth and metastases. In this report, we investigated whether the level of HIF-1 alpha is increased during carcinogenesis in breast tissue and is associated with other tumor biomarkers. METHODS: Paraffin-embedded clinical specimens from five pathologic stages of breast tumorigenesis and from normal breast tissue were used. HIF-1 alpha protein and the biomarkers vascular endothelial growth factor (VEGF), HER-2/neu, p53, Ki-67, and estrogen receptor (ER) were identified immunohistochemically, and microvessel density (a measure of angiogenesis) was determined. Associations among levels of HIF-1 alpha and these biomarkers were tested statistically. All statistical tests are two-sided. RESULTS: The frequency of HIF-1 alpha-positive cells in a specimen increased with the specimen's pathologic stage (P<.001, chi(2) test for trend) as follows: normal breast tissue (0 specimens with > or = 1% HIF-1 alpha-positive cells in 10 specimens tested), ductal hyperplastic lesions (0 in 10), well-differentiated ductal carcinomas in situ (DCIS) (11 in 20), well-differentiated invasive breast cancers (12 in 20), poorly differentiated DCIS (17 in 20), and poorly differentiated invasive carcinomas (20 in 20). Increased levels of HIF-1 alpha were statistically significantly associated with high proliferation and increased expression of VEGF and ER proteins. In DCIS lesions, increased levels of HIF-1 alpha were statistically significantly associated with increased microvessel density. HIF-1alpha showed a borderline association with HER-2/neu but no association with p53. CONCLUSIONS: The level of HIF-1 alpha increases as the pathologic stage increases and is higher in poorly differentiated lesions than in the corresponding type of well-differentiated lesions. Increased levels of HIF-1 alpha are associated with increased proliferation and increased expression of ER and VEGF. Thus, increased levels of HIF-1 alpha are potentially associated with more aggressive tumors.

Drug resistance-associated marker Lrp for prediction of response to chemotherapy and prognoses in advanced ovarian carcinoma.

BACKGROUND: Drug resistance is a major impediment to the successful treatment of ovarian carcinoma. None of the earlier-identified resistance mechanisms, such as overexpression of the MDR1 gene product, P-glycoprotein (Pgp), has been shown to be a major determinant of clinical response to chemotherapy and survival for ovarian cancer patients. The multidrug resistance-associated protein (Mrp) and the lung resistance protein (Lrp, also called the p110 major vault protein), are newly described proteins associated with multidrug resistance in vitro. PURPOSE: The aim of this retrospective study was to investigate the expression of Mrp and Lrp, in addition to Pgp, in advanced ovarian carcinoma and to determine whether such expression was predictive of response to chemotherapy and survival. METHODS: Fifty-seven banked frozen specimens, previously collected and frozen at the time of diagnosis from an equal number of patients with International Federation of Gynecology and Obstetrics (FIGO) stage III or IV ovarian carcinoma, were immunostained for Pgp (with monoclonal antibodies [MAbs] MRK-16 and JSB-1), Mrp (with MAb MRPrl), and Lrp (with MAb LRP-56). All patients had received platinum- or alkylating-based chemotherapy after debulking surgery. Clinicopathologic parameters determined at diagnosis were retrospectively assessed for their relationship with Pgp, Mrp, and Lrp expression. Response to treatment and survival were compared between Pgp, Mrp, and Lrp expression groups. Qualitative variables were analyzed using Fisher's exact test or the chi-squared test. All reported P values are two-tailed. RESULTS: Nine (16%), 39 (68%), and 44 (77%) of the 57 tumor specimens examined showed positive immunostaining for Pgp, Mrp, and Lrp, respectively. Positive immunostaining for these proteins was not associated with any other prognostic factor examined. No association was found between Pgp and Mrp expression and response to chemotherapy and survival. In contrast, patients with Lrp-positive tumors had poorer response to chemotherapy (P = .004) and shorter progression-free (P = .003) and overall (P = .007) survival than Lrp-negative patients. Multivariate analysis of Lrp expression, FIGO stage, residual tumor after initial surgery, tumor grade, and presence or absence of ascites showed that only Lrp status was independently related to both progression-free survival and overall survival. CONCLUSIONS: Positive Lrp immunostaining in advanced ovarian carcinoma appears to be an indicator of poor response to standard chemotherapy (platinum or alkylating agents) and of adverse prognoses. IMPLICATIONS: The functional characterization of Lrp and related proteins may reveal new approaches to modulate Lrp-associated drug resistance. A large prospective study is warranted to confirm the prognostic value of Lrp.

Sensitivity of human, murine, and rat cells to 5-fluorouracil and 5'-deoxy-5-fluorouridine in relation to drug-metabolizing enzymes.

Six cell lines differing in histological origin were studied regarding the growth inhibitory effect of fluoropyrimidines in relation to their metabolism. The human colon carcinoma cell line WiDr was most sensitive to 5-fluorouracil (FUra) (50% growth inhibitory concentration, 0.7 microM) and to its analogue 5'deoxy-5-fluorouridine (5'dFUR) (50% growth inhibitory concentration, 18 microM). The murine B16 melanoma cell line was moderately sensitive to FUra but least sensitive to 5'dFUR. The 50% growth inhibitory concentration values in the human melanoma cell lines IGR3 and M5, the transformed human intestine cell line intestine 407 and the rat hepatoma cell line H35 varied for FUra between 1.7 and 5.0 microM, and for 5'dFUR between 54 and 160 microM. Several enzymes from pyrimidine metabolism responsible for FUra metabolism were measured with FUra as a substrate. The activity of uridine phosphorylase, which catalyzes the conversion of 5'dFUR to FUra, was lowest in B16 cells correlating with the low sensitivity to 5'dFUR. When adenosine 5'-triphosphate was included in the reaction mixture for uridine phosphorylase, FUra was rapidly channeled into FUra nucleotides via its nucleoside. The rate of channeling appeared to correlate with the nucleoside phosphorylase activity in the various cell lines. In several cell lines activities of nucleotide-degrading enzymes were rather high and interfered with the measurement of orotate phosphoribosyl transferase (OPRT) with FUra as substrate. Addition of the phosphatase inhibitor glycerol-2-phosphate partly prevented breakdown of the newly formed 5-fluorouridine 5'-monophosphate and enabled measurement of OPRT. The WiDr cell line had a relatively high OPRT activity which could explain its sensitivity to FUra. The activity of thymidylate synthase was measured at a suboptimal concentration of 1 microM and at the optimal concentration of 10 microM deoxyuridine 5'-phosphate. With all cell lines the ratio between the activities at 10 and 1 microM was between 2.3 and 3.6. The activity of thymidylate synthase was lowest in WiDr and IGR3 cells and 3-4 times higher in M5 and Intestine 407 cells. The inhibition of 0.01 microM 5-fluorodeoxyuridine 5'-monophosphate was 80-90% at 1 microM deoxyuridine 5'-phosphate and 50-70% at 10 microM deoxyuridine 5'-phosphate with all cell lines. At 0.1 microM 5-fluorodeoxyuridine 5'-monophosphate enzyme activity was inhibited by 95-100%. The incorporation of FUra into RNA was relatively low in IGR3 cells and 3-5 times higher in all other cell lines.(ABSTRACT TRUNCATED AT 400 WORDS)

The reversal of methotrexate cytotoxicity to mouse bone marrow cells by leucovorin and nucleosides.

The cytotoxic effect of methotrexate (MTX) for mouse bone marrow cells has been studied by in vitro of the granulocyte precursor cell (CFU-C) in a medium containing dialyzed fetal calf serum and dialyzed L-cell supernatant. The formation of 50-cell colonies was inhibited to 50% of control by 10(-8) M MTX. Further increases in MTX concentration rapidly abolished colony formation by CFU-C. The potential of leucovorin and nucleosides to rescue the CFU-C from MTX toxicity was studied. Toxicity of 10(-7) M MTX was completely reversed by equimolar concentrations of leucovorin, but with higher MTX concentrations, relatively more leucovorin was required. While 10(-5) M MTX was rescued by 10(-3) M leucovorin, rescue of the toxic effect of 10(-4) M MTX by 10(-3) M leucovorin was not observed. In contrast to the rescue by Leucovorin, toxicity of all MTX concentrations up to 10(-4) M was completely prevented by 10(-5) M thymidine with 10(-5) M adenosine, inosine, or hypoxanthine. Single nucleosides or thymidine with guanosine were ineffective, as were lower concentrations (less than or equal to 10(-6)M) of the effective combinations. Thus, while leucovorin reversed the MTX toxicity to CFU-C competitively, rescue by nucleosides was noncompetitive. The significance and possible usefulness of these findings for chemotherapeutic protocols are discussed.

Effect of endogenous glutathione, superoxide dismutases, catalase, and glutathione peroxidase on adriamycin tolerance of Chinese hamster ovary cells.

Based on the concept that activated oxygen species are causally involved in Adriamycin toxicity, endogenous antioxidant defenses are expected to be important determinants of cellular Adriamycin tolerance. We have tested this prediction by making use of an oxygen-resistant variant subline of Chinese hamster ovary cells (CHOr), which is characterized by increased levels of glutathione, copper- and zinc-containing superoxide dismutase, manganese-containing superoxide dismutase, catalase, and glutathione peroxidase. The levels of antioxidant defenses in wild-type CHO (CHOs) cells were within the range reported for human tumor cell lines, except for catalase, which was comparatively high. Oxygen-tolerant CHOr cells, which contained 4.3-fold more catalase activity than CHOs cells, were proportionally more resistant to H2O2, indicating that catalase activity in wild-type CHOs cells was still limiting H2O2 tolerance. The Adriamycin sensitivity of CHOs cells was compared to that of CHOr cells by clonogenic cell survival. After correcting for differential drug uptake in CHOs and CHOr cells, no significant difference in Adriamycin sensitivity could be detected. Furthermore, drug-induced cyanide-resistant oxygen consumption and electron spin resonance data indicated that both cell strains were equally efficient in reducing Adriamycin to its semiquinone radical and in generating activated oxygen species through oxidation-reduction cycling. These results indicate that Adriamycin tolerance of wild-type CHO cells, as determined by clonogenic cell survival, is not limited by endogenous glutathione, copper- and zinc-containing superoxide dismutase, manganese-containing superoxide dismutase, catalase, or glutathione peroxidase.