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Biomedical subjects

D J Kerr

Publications and source records attributed to D J Kerr.

At least 73 records · Page 4Linked to original sources
PubMed1998

Regulation of c-fos transcription by chemopreventive isoflavonoids and lignans in MDA-MB-468 breast cancer cells.

Isoflavonoids and lignans are diet constituents with chemopreventive properties. We compared the ability of the isoflavonoids genistein and equol, the lignans enterodiol, enterolactone and nordihydroguaiaretic acid (NDGA) and the lignan metabolite methyl p-hydroxyphenyllactate to interfere with mitogenic and tumour promotional signal transduction pathways. Their effects on c-fos mRNA levels after induction by either epidermal growth factor (EGF) or the tumour promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) was measured in human breast cancer-derived MDA-MB-468 cells. Of the six agents, only genistein decreased EGF-induced, c-fos transcription (by 63% compared to control at 100 mumol/l). In contrast, both genistein and equol at 100 mumol/l decreased TPA-induced c-fos levels, by 75 and 67%, respectively. NDGA and methyl p-hydroxyphenyllactate did not inhibit TPA mediated c-fos transcription and enterolactone and enterodiol had only a weak inhibitory effect. NDGA at 0.1-10 mumol/l increased c-fos mRNA levels. None of the agents inhibited protein kinase C and only genistein inhibited EGF receptor-linked protein tyrosine kinase obtained from MDA-MB-468 cells, with an IC50 of 60 mumol/l. NDGA and genistein arrested cell colony formation potently, genistein was 15-fold more growth-inhibitory than equol. The results suggest that both genistein and equol interfere similarly with TPA-induced signal transduction pathways. Inhibition by genistein of EGF-induced c-fos mRNA transcription is probably related to its interruption of EGF receptor-linked protein tyrosine kinase, whereas genistein-induced growth arrest is not. If ability to antagonise phorbol ester effects is important for chemopreventive efficacy, equol and genistein might be equi-efficacious chemopreventors, whereas enterolactone, enterodiol and NDGA should be much less potent. If phorbol ester antagonism together with antimitogenic activity determine optimal chemopreventive activity of this type of agent, genistein would be more potent than equol.

Breast Neoplasms↗
PubMed1998

Anti-proliferative activity and mechanism of action of titanocene dichloride.

Development of resistance to cytotoxic agents is a major limitation to their clinical use. Novel compounds are synthesized with a view to develop non-cross-resistant, less toxic and more potent activity. The detection of the anti-tumour properties of the inorganic compound cisplatin stimulated a broad search for other metal-containing complexes. Titanocene dichloride was synthesized on this basis and has shown potent anti-neoplastic activity in experimental animals. We have examined the in vitro activity of titanocene dichloride in two pairs of platinum-sensitive and resistant human ovarian carcinoma cell lines, A2780/2780CP and CH1/CH1cisR, and in mutated p53- and bcl-2-transfected clones of A2780 cells. A time- and concentration-dependent anti-proliferative effect was observed in all cell lines treated with titanocene dichloride. The drug was found to significantly overcome platinum resistance in the 2780CP and the CH1 cisR cell lines and in the bcl-2 and the mutant p53 transfectants of A2780 cells. Titanocene dichloride induced a block in late S/early G2 phase of the cell cycle; however apoptotic cell death occurred from any phase of cycle. Titanium-DNA adducts were detected in A2780 cells treated with titanocene dichloride using atomic absorption spectrometry, suggesting that DNA may be a target for this drug. In agreement with this finding, p53 accumulated rapidly in drug-treated A2780 cells, indicative of a role for titanocene dichloride as a DNA-damaging agent. We have also performed studies to determine whether titanocene dichloride could demonstrate synergy with other cytotoxic agents in vitro. Isobologram analysis of cytotoxicity data obtained suggests that the combination of titanocene dichloride and 5-fluorouracil (5-FU) is synergistic. The potent in vivo anti-tumour activity of this compound, supported by the encouraging results from two phase I clinical trials, suggests that titanocene dichloride could be a promising novel chemotherapeutic agent.

Antineoplastic Agents↗
PubMed1998

Adenoviral delivery of B7-1 (CD80) increases the immunogenicity of human ovarian and cervical carcinoma cells.

The majority of tumour cells do not express immune costimulatory molecules and this may account for their inability to stimulate directly an antitumour T cell response. Here we report on the construction of a recombinant E1/E3-deleted adenovirus encoding the human B7-1 costimulatory molecule. We explored the use of this vector for gene transfer to a number of human ovarian and cervical tumour cell lines, and to primary ovarian tumour material. Rapid and efficient gene transfer and expression was obtained in the majority of cases using a multiplicity of infection of 30 plaque forming units per cell. B7-1 expression was detectable at the cell surface within 12 h and was still detectable 10 days after infection. The immunogenicity of gene-modified tumour cells was tested in an allogeneic mixed lymphocyte tumour cell culture. Tumour cells expressing B7-1 were found to induce significantly higher levels of T cell proliferation than tumour cells modified with a control adenovirus carrying the beta-galactosidase gene. B7-1-induced T cell proliferation could be blocked by the addition of anti-B7-1 antibodies at the initiation of cocultures. These results support the rationale for use of adenovirally delivered B7-1 for genetic immunotherapy of ovarian and cervical cancer.

Adenoviridae↗
PubMed1998

Virus directed enzyme prodrug therapy for ovarian and pancreatic cancer using retrovirally delivered E. coli nitroreductase and CB1954.

Expression of the E. coli enzyme nitroreductase (NTR) in tumour cells enables them to activate the prodrug CB1954 (5-(aziridin-1-yl)-2,4-dinitrobenzamide), leading to interstrand DNA crosslinking and cell death. Using transfected or retrovirally transduced SKOV3 ovarian carcinoma cell clones, we show a strong correlation between sensitivity to CB1954 and level of NTR enzyme activity. Importantly for clinical application in ovarian cancer, a cisplatin-resistant ovarian tumour cell line remains as susceptible to the NTR-dependent cytotoxicity of CB1954 as parental cells. In mixed populations of NTR-expressing and non-expressing cells, we observe a marked 'bystander killing' effect with this system. The use of NTR-encoding retroviruses from clonal producer cell lines at titres of 5 x 10(5) c.f.u./ml to transduce either established or low passage primary ovarian carcinoma lines only achieves an average 10-fold sensitisation of the cultures at gene transfer efficiencies of 15-25%. Concentration of the retrovirus to 3 x 10(7) c.f.u./ml elevates gene transfer to 80-90% in a single exposure to target cells, resulting in up to 500-fold sensitisation of the entire, unselected SKOV3 population to CB1954. In an initial investigation of NTR/CB1954 for the treatment of tumours in vivo, we observe regression of tumours expressing NTR following administration of CB1954, resulting in significantly increased median survival.

Animals↗
PubMed1998

Phase I trial of weekly scheduling and pharmacokinetics of titanocene dichloride in patients with advanced cancer.

PURPOSE: To determine the maximum-tolerated dose (MTD) and the dose-limiting toxicities (DLTs) of a weekly schedule of titanocene dichloride (TD) and to define the pharmacokinetics of titanium in plasma and urine. PATIENTS AND METHODS: Twenty patients with a median age of 58 years received 83 courses of TD. TD was given as 1-hour infusion at escalating doses from 70 to 185 mg/m2/wk. Pharmacokinetic analysis was performed in eight patients for total plasma titanium (TPTi) and in three patients for ultrafiltrable titanium (UFTi). RESULTS: At the fifth dose level (185 mg/m2/wk), a variety of DLTs were seen in five patients: fatigue in three, bilirubinemia in one, and hypokalemia in two. A further six patients were treated at 140 mg/m2; only one had dose-limiting creatinine elevation and this dose was therefore defined as the MTD. No myelosuppression or alopecia were observed. One patient with adenocarcinoma of unknown primary had a minor response. Pharmacokinetic analysis showed that TPTi maximum concentration (Cmax) values were linear with dose and elimination of TPTi was triphasic with a long terminal half-life (t1/2; median, 165 hours; range, 89 to 592). Between 7% and 24.3% of the total of administered titanium was eliminated in urine over the first 24 hours. In contrast, UFTi elimination was described by a one-compartment model with a t1/2 of 0.41 hours; peak levels of UFTi were 5.2% +/- 2.5% those of TPTi. CONCLUSION: The MTD of TD given on a weekly schedule is 140 mg/m2, with cumulative, but reversible creatinine and bilirubin elevation being the DLTs.

Adult↗
PubMed1998

A novel dosage approach for evaluation of SMANCS [poly-(styrene-co-maleyl-half-n-butylate) - neocarzinostatin] in the treatment of primary hepatocellular carcinoma.

We report a Phase I/II clinical trial of poly-(styrene-co-maleyl-half-n-butylate)-neocarzinostatin (SMANCS) for intra-arterial treatment of hepatoma. Early patients received 4 or 8 mg SMANCS dissolved in Lipiodol; later patients were treated according to tumour size and degree of filling achieved. SMANCS/Lipiodol drained rapidly from normal liver but was retained within tumour interstitium. Tumour nodules filled with SMANCS/Lipiodol usually stabilised and often regressed. No UICC criteria-defined responses were achieved, partly due to difficulties of filling several lesions simultaneously. Signs of therapeutic activity suggest a more extensive clinical study is warranted.

Abdominal Pain↗
PubMed1998

Novel therapeutic strategies for colorectal cancer.

Advanced colorectal cancer is a significant cause of cancer mortality in industrialized countries. 5-fluorouracil has remained the principal drug used in treating this disease, and although it has tangibly improved patient outcome, further gains can potentially be made. This review focuses on the current development of novel therapeutic agents which have potential in the treatment of colorectal cancer.

Colorectal Neoplasms↗
PubMed1997

Inhibition of phospholipid signalling and proliferation of Swiss 3T3 cells by the wortmannin analogue demethoxyviridin.

Growth factors and certain oncogenes activate a range of phospholipid-mediated signal transduction pathways resulting in cell proliferation. Demethoxyviridin (DMV), a structural analogue of wortmannin and recently reported as a potent inhibitor of phosphoinositide-3-kinase, inhibited bombesin plus insulin-stimulated increase in cell number in Swiss 3T3 cells, a model of cell proliferation. The drug produced cytostatic effects at concentrations below 1 microM and cytotoxic effects at 10 microM. In intact Swiss 3T3 cells DMV inhibited insulin-stimulated PI 3- and 4-kinases and bombesin-stimulated phospholipases C, D and A2 in the nanomolar range. DMV also inhibited bombesin-stimulated tyrosine phosphorylation of a range of proteins at nM concentrations. This study shows that DMV inhibited multiple stimulated signalling pathways which lead to increased Swiss 3T3 cell proliferation. A stable analogue of DMV may have chemotherapeutic potential.

3T3 Cells↗
PubMed1997

Simultaneous gas chromatographic-mass spectrophotometric determination of alpha-fluoro-beta-alanine and 5-fluorouracil in plasma.

A gas chromatographic-mass spectrometric (GC-MS) method is reported for simultaneous determination of alpha-fluoro-beta-alanine (FBA), the major end metabolite of 5-fluorouracil (5-FU), and 5-FU in plasma samples isolated from cancer patients. 5-Chlorouracil (5-CIU, 1 micrograms/ml) is added to samples as an internal standard. The method relies on protein precipitation of the plasma sample followed by derivatisation with pentafluorobenzyl bromide. Following sample purification with Sep-pak C18 columns the derivatives are analysed by GC-MS, with FBA, 5-FU and 5-CIU being determined at 36.96-37.03, 46.91-46.98 and 51.99-52.13 min, respectively. The ions measured in each case had m/z of 390, 490 and 506, respectively. The method showed good reproducibility with coefficients of variation between 3 and 10%, with a detection limit of < 1 ng/ml for 5-FU and < 5 ng FBA/ml plasma. The possibility of sensitive determination of FBA without the use of radioisotopes should permit routine estimation of rates of 5-FU metabolism in individual patients.

Antimetabolites, Antineoplastic↗
PubMed1997

Spontaneous pneumothorax associated with expectoration of a lump of metastatic renal cancer.

The case report of a patient known to have metastatic renal cancer and right main bronchus obstruction is presented. During an episode of haemoptysis, the patient expectorated a large fragment of tissue, which proved to be metastatic renal cell cancer. This event produced a right-sided hydropneumothorax with partial re-expansion of the previously collapsed right lung. A chest tube was inserted producing a full re-expansion, following which pleurodesis with tetracycline was performed. To our knowledge, this is the first ever description of spontaneous clearance of a malignant bronchial obstruction.

Bronchial Diseases↗
PubMed1997

A phase II study of regional 2-weekly 5-fluorouracil infusion with intravenous folinic acid in the treatment of colorectal liver metastases.

Forty patients with unresectable colorectal metastases confined to the liver were evaluated in a phase II study. 5-Fluorouracil (5-FU) was delivered via a surgically placed hepatic artery catheter. Patients received folinic acid (200 mg m-2) intravenously over 2 h followed by a loading dose of intra-arterial 5-FU (400 mg m-2) over 15 min, then 5-FU (1600 mg m-2) by intra-arterial infusion over the following 22 h. This was repeated on day 2 and the whole schedule was repeated every 2 weeks. Response was assessed after six treatments. The median follow-up was 17 months. Overall response rate was 46% with 8% complete response. Estimated median survival is 19 months. Site of progression was the liver alone in 55%, liver and lung in another 16% and 29% in other sites. Eight patients experienced grade 3 or 4 toxicity. The response rate of this regimen compares favourably with reported trials of intra-arterial FUDR, and our schedule is currently being compared with a similar schedule of intravenous 5-FU and folinic acid in a randomized Medical Research Council trial (CR05).

Adult↗
PubMed1997

Clinical efficacy of 'Tomudex' (raltitrexed) in advanced colorectal cancer.

Direct and specific thymidylate synthase inhibitors, such as raltitrexed ('Tomudex', formerly ZD1694), provide a promising new therapeutic approach to the treatment of advanced colorectal cancer. Two international phase III trials (studies 3 and 12) compared raltitrexed (3 mg/m2) with 5-fluorouracil plus low-dose leucovorin or plus high-dose leucovorin, respectively. Study 3 included a 15.5-month follow-up for efficacy and a 26-month follow-up for survival. Results of an interim analysis for study 12 are presented. Objective tumour response rates for each treatment group were comparable in both studies 3 (P=0.48) and 12 (P=0.896). The median time to progression was similar between treatments in study 3 (P=0.44), but was significantly longer for 5-fluorouracil + leucovorin compared with raltitrexed in study 12 (5.1 versus 3.9 months, P=0.005). The median survival (raltitrexed versus 5-fluorouracil + leucovorin) was comparable in both studies 3 (10.1 versus 10.2 months, P=0.42) and 12 (10.7 versus 11.8 months, P=0.36). Palliative benefits were similar between treatments in both studies. A third phase III trial (study 10), carried out in North America, demonstrated a statistically significantly longer median survival for 5-fluorouracil + leucovorin compared with raltitrexed (12.7 months versus 9.7 months; P=0.01). However, the possible unfamiliarity of the clinicians with raltitrexed and the early discontinuation of a 4 mg/m2 raltitrexed arm due to toxicity may have led to an unconscious investigator bias in this trial, leading to a non-protocol-led withdrawal of patients from the study. Overall, raltitrexed is comparable with standard 5-fluorouracil + leucovorin therapy in terms of response rates and overall survival, and has a more convenient dose schedule.

Animals↗
PubMed1997

The costs of managing advanced colorectal cancer: a broad perspective.

Cancer care is expensive, consuming between 5 and 10% of health-care resources in industrialized countries. Therefore increasing emphasis is being placed on the value of treatment interventions. Colorectal cancer is the second most common cancer in the Western world and nearly two-thirds of patients will require palliative treatment. Only limited data are available on the cost of palliative chemotherapy for patients with advanced disease. The profile of raltitrexed ('Tomudex', formerly ZD1694) suggests that it may reduce costs associated with the administration of chemotherapy. Recent studies demonstrate that the total monthly cost of raltitrexed is lower or about the same as a variety of commonly used 5-fluorouracil-based regimens and offers potential savings for hospitals in terms of demand on specialist facilities, physician, nursing and pharmacy time, and overnight bed occupancy. The personal cost borne by patients and their carers for travelling and time off work is reduced with raltitrexed compared with the widely used Mayo regimen. However, there may be disincentives within certain national health-care systems to the introduction of a more resource-efficient drug such as raltitrexed. Physicians will need information on both the benefits and costs of drug treatments to be able to make informed decisions on the provision of high quality, cost-effective patient care, and it is likely that health economic assessment will be incorporated into increasing numbers of clinical trials.

Antimetabolites, Antineoplastic↗
PubMed1997

ESPAC-1 trial progress report: the European randomized adjuvant study comparing radiochemotherapy, 6 months chemotherapy and combination therapy versus observation in pancreatic cancer.

At the joint International Association of Pancreatology and European Pancreatic Club meeting at King's College, London (July 9-12, 1997), a satellite meeting of the European Study Group for Pancreatic Cancer (ESPAC) met to discuss the progress of the ESPAC-1 trial. This study will address which, if any, of the following adjuvant treatments are of benefit in patients with resectable pancreatic cancer: radiotherapy (40 Gy with 5-fluorouracil as a sensitising agent); 6 months chemotherapy (5-fluorouracil and folinic acid), or a combination of these treatments. The study, which commenced in 1994, had already recruited 348 patients into the 3 treatment arms and 1 control arm of the study by May 31, 1997. This is the largest study of its kind in pancreatic cancer and should definitively address the question of the role of conventional methods of adjuvant treatment in pancreatic cancer.

Chemotherapy, Adjuvant↗
PubMed1996

CD40-induced growth inhibition in epithelial cells is mimicked by Epstein-Barr Virus-encoded LMP1: involvement of TRAF3 as a common mediator.

CD40, a member of the tumour necrosis factor receptor family, is expressed on the surface of B lymphocytes where its ligation provides a potent survival signal. CD40 is also expressed in basal epithelial cells and in a number of different carcinomas where its function remains unknown. We observed that contrary to the studies in normal B cells, CD40 ligation in carcinoma cell lines and in normal primary epithelial cells resulted in growth inhibition and enhanced susceptibility to apoptosis induced by anti-neoplastic drugs, TNF-alpha, Fas and ceramide. This effect was also observed in CD40-transfected Rat-1 fibroblasts. The expression of Bcl-2 did not affect growth inhibition induced by CD40 ligation in epithelial cells but the Epstein - Barr Virus-encoded latent membrane protein 1 (LMP1) blocked the effect. Whilst transient expression of LMP-1 resulted in the inhibition of epithelial cell growth, this effect was not observed with a LMP1 mutant lacking the binding domain for TRAF3, a protein which may mediate signal transduction by interacting with the cytoplasmic domains of both CD40 and LMP1. Transient expression of TRAF3 also inhibited epithelial cell growth, whilst expression of a dominant-negative TRAF3 partially blocked the inhibitory effect of CD40 ligation and of transient LMP1 expression. These results suggest that CD40 regulates epithelial cell growth in a manner mimicked by LMP1 and implicate TRAF3 as a common mediator in the transduction of the growth inhibitory signals generated via the CD40 and LMP1 pathways.

Animals↗
PubMed1996

The prognostic significance of Bcl-2 and p53 expression in ovarian carcinoma.

Advanced ovarian cancer is characterized by poor prognosis and the development of resistance to chemotherapy. We have found that Bcl-2 and p53, two proteins implicated in the control of apoptosis, are differently expressed in the ovarian cell line A2780 and its cisplatin-resistant variant 2780CP, with the resistant line overexpressing both proteins. Transfection of the A2780 cells with a Bcl-2- or p53-expressing plasmid increases resistance to various drugs, including cisplatin, suggesting that Bcl-2 and p53 expression may influence the sensitivity of ovarian cancer cell lines to chemotherapy. Expression of these two proteins in vivo was determined by immunohistochemical staining of ovarian tumor biopsies from 70 patients. We found that Bcl-2 and p53 were expressed in 57 and 61% of specimens examined, respectively. Both p53 and Bcl-2 were found to be independent prognostic indicators of survival in ovarian cancer. Survival was poorer in patients with tumors expressing high levels of p53, whereas expression of Bcl-2 was associated with improved survival.

Drug Resistance, Neoplasm↗