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D W Hedley

Publications and source records attributed to D W Hedley.

At least 19 recordsLinked to original sources
PubMed1992

Multifactorial resistance to antineoplastic agents in drug-resistant P388 murine leukemia, Chinese hamster ovary, and human HeLa cells, with emphasis on the role of DNA topoisomerase II.

The role of DNA topoisomerase II in multifactorial resistance to antineoplastic agents is reviewed. We have previously observed that in Adriamycin (ADR) resistant P388 murine leukemia cells, DNA topoisomerase II enzyme content and cleavage and catalytic activities were all reduced and correlated with drug sensitivity. A subsequent study provided evidence for an allelic mutation of the gene for DNA topoisomerase II as a possible molecular mechanism underlying the enzyme alterations. To ascertain how universal were these observations, a study was undertaken of DNA topoisomerase II (topo II) in other cell lines resistant either to ADR or another topo-II-interactive drug, mitoxantrone. In ADR-resistant Chinese hamster ovary (CHO) cells, topo II cleavage and catalytic activities and the gene product were all reduced; however, only cleavage activity correlated with drug sensitivity. No differences were noted between ADR-sensitive and -resistant CHO cells by Northern or Southern blot analysis, raising the possibility that the enzyme in resistant cells may be regulated at a posttranscriptional level. Findings on a gel retardation or immunoblot band depletion assay showed that the enzyme in CHO/ADR-1 cells failed to bind to the DNA-drug-enzyme complex, suggesting a qualitative as well as quantitative enzyme alteration in those cells. Mitoxantrone-resistant HeLa cells (Mito-1) displayed not only a lower level of cleavage activity but also of enzyme content and catalytic activity, relative to the parental drug-sensitive HeLa cells. As with the CHO cells, no differences were noted between mitoxantrone-sensitive and -resistant HeLa cells on Northern and Southern blot analyses, suggesting that enzyme regulation in these resistant cells may also be at a posttranscriptional level. There was no evidence of enzyme binding to DNA-drug-enzyme complex in resistant HeLa/Mito-1 cells, once again suggesting the presence of a qualitative enzyme alteration. The findings in both ADR-resistant CHO cells and mitoxantrone-resistant HeLa cells do not exclude the possibility that subtle changes in the topoisomerase II gene, such as point mutations, may account for these enzyme changes. The apparent qualitative changes observed in enzyme may result from posttranslational modifications such as phosphorylation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1990

Flow cytometric measurement of glutathione content of human cancer biopsies.

Rice et al. (1986) have described a flow cytometric method where the non-fluorescent probe monochlorobimane (mBCl) forms a fluorescent adduct with cellular glutathione (GSH) under the action of glutathione-S-transferase. We show here that for EMT6 carcinosarcoma cells there is a close correlation between mean cell fluorescence, expressed as a ratio to that of fluorescence calibration beads, and biochemically determined GSH content over the range 0.2-2.0 fmol cell-1. Single cell suspensions from 14 human cancers were prepared by 23-gauge needle aspiration or mechanical disaggregation of surgical specimens, stained using mBCl and examined by flow cytometry. There was a wide range in individual cell fluorescence, which in contrast to EMT6 cells was not strongly correlated with Coulter volume. By comparing tumour cell fluorescence to that of calibration beads, and assuming that the relationship with GSH content for EMT6 holds for other cells, a mean GSH content of 0.95 fmol cell-1 was derived for nine carcinomas, and 0.21 fmol cell-1 for five non-Hodgkin's lymphomas. Although this semi-quantitation needs further validation, the method used here is rapid, gives an indication of heterogeneity of tumour cell GSH content, and can be applied to fine needle biopsy samples. It therefore shows promise as a means for studying prospectively the relationship of GSH content to clinical drug and radiation sensitivity, and for monitoring the effects of agents such as buthionine sulphoximine which are intended to improve treatment results through tumour cell GSH depletion.

Biopsy, Needle↗
PubMed1989

Flow cytometry using paraffin-embedded tissue: five years on.

The use of paraffin-embedded tissue for flow cytometry is reviewed. A number of technical modifications of the original 1983 method have been described, aimed at improving the accuracy of DNA measurements by minimizing cell debris or reducing coefficients of variation, and at simplifying sample preparation. Over 100 clinical studies have now been reported, mainly assessing the effect of DNA index on prognosis, and those published up until mid-1988 are summarized in an appendix. More recently there have been developments in the use of monoclonal antibodies to measure oncogene products or proliferation markers in addition to DNA content. Detailed clinical evaluation and standardization of these more sophisticated methods is still some way ahead, but as was the case with DNA index, the use of archival material from patients whose outcome is already known should speed this process.

Animals↗
PubMed1989

Flow cytometric measurement of intracellular pH in B16 tumors: intercell variance and effects of pretreatment with glucose.

Flow cytometry was used to measure cytoplasmic pH (pHi) of B16 melanoma cells taken from tumor-bearing animals. We used a ratiometric method to allow measurements on an individual cell basis which were independent of cellular content of the pH indicator BCECF. In order to "freeze" any intercell variance which may have existed within the tumor mass, tumors were mechanically disaggregated in bicarbonate-free medium containing 0.5 mM amiloride at 4 degrees C and loaded with BCECF in choline chloride-based Earle's solution at 37 degrees C. Studies using cells grown in vitro showed that this protocol prevented acid load recovery during the 30-min period typically required between tumor excision and pHi measurement. A calibration curve was obtained by resuspending BCECF-stained cells in a range of buffers containing the proton ionophore nigericin. The range of values for individual cells was estimated by comparing the coefficient of variation of the test sample with that obtained when nigericin was used to reduce all cells to the pHi of the calibration buffer. The average value for mean tumor cell pH was 7.32 +/- 0.05 SD. Pretreatment of animals with intraperitoneal glucose for one hour resulted in an average for mean pHi of 7.17 +/- 0.17 SD. Mean coefficient of variation was 8.7%, and in the presence of nigericin, 8.1%. These values indicate a variance in measured pHi of approximately +/- 0.4 pH units, but most of this results from experimental error rather than true intercell pHi variance. The method used here is capable of detecting reduction in mean tumour pHi caused by ip glucose, but incapable of precise estimation of individual cell values. Despite these uncertainties, the results suggest that the range of pHi within B 16 tumors is small.

Amiloride↗
PubMed1988

Effect of gallium on DNA synthesis by human T-cell lymphoblasts.

We have studied the antiproliferative effects of gallium nitrate in cultured CCRF-CEM lymphoblasts. The 50% inhibitory dose for these cells was 120 microM, and after 24 h at a cytostatic concentration (480 microM) S-phase arrest was observed by DNA flow cytometry. Deoxyribonucleoside triphosphate pools were all reduced (dATP, dGTP, and dCTP by 50%, dTTP by 25%), suggesting inhibition of ribonucleotide reductase. Administration of tracer amounts (0.5 microM) of either [3H]uridine or [3H]deoxyuridine confirmed that DNA synthesis had been inhibited to 20% of control rates by gallium. Further, the flow of the ribonucleoside into the dTTP pool and DNA was selectively reduced compared to that of the deoxyribonucleoside. Gallium decreased the specific activity of dTTP labeled from uridine by 50%, whereas the specific activity of dTTP labeled from deoxyuridine was increased 2.5-fold. Thus counts in DNA derived from [3H]uridine were decreased by more than 80%, while counts in DNA derived from [3H]deoxyuridine were virtually unaltered. Uridine incorporation into RNA was not affected. Gallium did not significantly alter the capacity of permeabilized naive cells to incorporate [3H]dTTP into DNA, while 24-h gallium pretreatment (which increased the percentage of S-phase cells) produced a modest increase in [3H]dTTP incorporation, indicating that any effect of gallium on DNA polymerase alpha is minor. Gallium treatment did not induce or inhibit the repair of DNA single strand breaks. These data demonstrate that gallium inhibits replicative DNA synthesis, with the major specific enzyme target probably being ribonucleotide reductase.

Antineoplastic Agents↗
PubMed1988

Prediction of long-term survival by flow cytometric analysis of cellular DNA content in patients with advanced ovarian cancer.

The prognostic value of cellular DNA content in ovarian cancer (malignant common epithelial tumors) was investigated by flow cytometric analysis of paraffin-embedded tumor blocks from 128 previously untreated patients with International Federation of Gynecology and Obstetrics (FIGO) stage III and IV ovarian cancer entered in a prospective clinical trial of combination v sequential therapy with chlorambucil and cisplatin. Seventy-three percent of tumors were aneuploid and 27% were diploid. Multivariate analysis using a Cox model showed that cellular DNA content (P less than .001) and FIGO stage (P less than .02) were the only significant independent prognostic variables. The median survival was 13 months for patients with aneuploid tumors and 60 months for patients with diploid tumors (P less than .0001). Further analysis indicated that the good prognosis associated with diploid tumors was limited to patients with stage III disease, all patients with stage IV (spread beyond the peritoneal cavity or liver metastases) disease having a poor prognosis irrespective of ploidy. On pathological review, nine borderline ovarian tumors (of low malignant potential) were identified, and seven of these were diploid. These tumors have an unusually favorable prognosis, despite apparent dissemination within the peritoneal cavity, a paradox which is often difficult to explain using conventional histological criteria. Although the vast majority of tumors in this study (93%) were classified as invasive epithelial ovarian cancers, it is possible that some of the patients with stage III diploid tumors may have had malignancies that were predominantly of low malignant potential, thus accounting in part for the prognostic significance of DNA content. By incorporating flow cytometric DNA analysis with careful histopathological assessment, it may be possible to better identify patients with an inherently good prognosis. This assumes particular importance, as the relatively favorable prognosis of patients with stage III diploid ovarian tumors appears to be independent of the type of treatment.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1987

Association of DNA index and S-phase fraction with prognosis of nodes positive early breast cancer.

DNA index and S-phase fraction of 490 primary breast carcinomas were measured by flow cytometry, using paraffin-embedded tissue as a starting point. All patients had involvement of axillary lymph nodes and all were randomized onto one of the Ludwig Breast Cancer Trials I-IV between July 1978 and August 1981. The presence of an abnormal DNA stemline correlated with involvement of four or more axillary lymph nodes (P = 0.09), postmenopausal status (P = 0.008), estrogen receptor negativity (P = 0.03), and high tumor grade (P = 0.0005). Disease-free and overall survival for these patients was worse than for those with tumors of normal DNA content, but DNA aneuploidy did not have independent prognostic significance when allowance was made for its correlation with other prognostic features. The percentage of cells in S phase, which is an index of cell proliferation, was also analyzed in 285 DNA histograms considered to be capable of giving a valid estimate. Disease-free survival for 154 patients with S phase less than or equal to 10% was significantly longer than for those with S phase greater than 10% (P = 0.0008). S-phase greater than 10% was strongly correlated with high tumor grade (P less than 0.00001) and abnormal DNA index (P less than 0.00001) but only weakly correlated with nodal, hormone receptor, and menopausal status. Multivariate analysis using a Cox proportional hazard model suggested that the prognostic significance of the percentage of S phase was related to the association with tumor grade. Because it gives rapid, objectively determined information about biological aggressiveness DNA flow cytometry may well establish a role in routine clinical practice, but further technical refinements are required before it can be used for treatment decision making in nodes positive early breast cancer patients.

Breast Neoplasms↗
PubMed1987

The prognostic significance of proliferative activity in poor histology non-Hodgkin's lymphoma: a flow cytometry study using archival material.

The DNA content and proliferative activity of paraffin-embedded lymph node tissue from 111 patients with poor histology non-Hodgkin's lymphoma were measured by flow cytometry. These patients had been entered into a prospective randomized trial which, to date, has shown no survival difference by treatment arm. Forty-four (40%) samples showed evidence of aneuploidy with three samples having more than one aneuploid population. The aneuploid populations had a bimodal distribution with one group having a DNA index between 1.1-1.3 and the other 1.8-2.2. The incidence of aneuploidy did not correlate with age, stage or survival. In 56 diploid samples the S phase values below 10% had a significantly better survival than those with S phase values above 10% (P less than 0.011). For patients with diffuse large cell histology the corresponding discriminatory S phase value was 19% (P less than 0.009).

Adult↗
PubMed1987

Immunohistochemical detection of proliferating cells in vivo.

Incorporation of the thymidine analogue 5-bromo-2'-deoxyuridine (BrUdR) into newly synthesized DNA provides the basis of a simple technique for identifying proliferating cells. BrUdR was administered to C57BL/6 mice by continuous infusion for 1-7 days, or by intraperitoneal injection for shorter intervals. Various tissue types, including gut, kidney, and liver, were excised, fixed in neutral buffered formalin, and paraffin-embedded for sectioning. De-paraffinized 4-micron tissue sections and bone marrow samples were incubated with an anti-BrUdR antibody and cells that had traversed S-phase during the BrUdR exposure period were identified immunohistochemically. Proliferation and migration of intestinal epithelial cells were identified by antibody staining after continuous in vivo exposure to BrUdR for 1-4 days, and BrUdR incorporation into proliferating marrow cells was detected within 30 min. Tissues such as normal liver, known to have low levels of proliferation, remained unstained after 3 days' exposure to BrUdR. After we established that normal proliferating cells could be identified using this technique, BrUdR was administered to mice bearing B16 melanomas. Again, proliferating tumor cells were clearly identified in histological sections. The nuclei from these paraffin-embedded tumors were also collected for flow cytometric analysis after de-waxing, rehydration, and pepsin treatment. This combination of techniques made possible the comparison in adjacent tissue sections of labeling index, obtained from stained sections, with percentage S-phase, measured using DNA flow cytometry. The % S-phase was consistently higher than the labeling index obtained with immunocytochemistry, and two-parameter DNA vs BrUdR flow cytometry showed that this difference could be accounted for by a population of unlabeled cells with an S-phase DNA content.

Animals↗
PubMed1987

Metastatic adeno or undifferentiated carcinoma from an unknown primary site--natural history and guidelines for identification of treatable subsets.

Two hundred and eighty-six patients presenting with metastatic adenocarcinoma or undifferentiated carcinoma whose primary site was not identified by clinical history, physical examination and chest radiograph have been studied. Median survival from presentation was 22 weeks. Factors independently predicting improved survival were lymph node presentations, good performance status and body weight loss of less than 10 per cent. In 88 (31 per cent) patients the primary tumour site was subsequently identified, in 58 (20 per cent) during life. Lung cancer was the most frequently identified primary tumour, and in only 32 (11 per cent) of the patients was a 'treatable' primary tumour (i.e. germ cell, breast, ovarian, prostate, thyroid cancer or lymphoma) identified. Among the treatable primary tumours were those in eight out of 16 female patients presenting with axillary metastases who were subsequently shown to have primary breast cancer and four of 13 females presenting with ascites who were found to have primary ovarian cancer. Prostatic cancer was confirmed in five out of 13 men with raised serum acid phosphatase. Of 22 patients with elevated serum alphafoetoprotein (AFP) or beta-human chorionic gonadotrophin levels (beta HCG) 18 had some features of the 'atypical teratoma syndrome'. Of the total of 32 patients with treatable tumour types, 29 (90 per cent) were identified during life. Median survival for patients with treatable tumour types identified during life was 104 weeks, compared with 22 weeks for the group as a whole. Retrospective immunocytochemical staining of the original biopsy showed that prostatic specific antigen and antibodies to beta HCG and AFP were diagnostically useful, but a series of organ site non-specific markers of histogenesis or cellular differentiation (carcinoembryonic antigen, secretory component for IgA, peanut lectin binding, epithelial membrane antigen and keratin) showed no significant correlations with identified primary sites, responsiveness to empirical chemotherapy or survival. Metastatic undifferentiated carcinoma or adenocarcinoma from an unknown primary site represents 6.5 per cent of all referrals to the medical oncology unit, Royal Prince Alfred Hospital, Sydney. We offer guidelines for the rapid identification of the limited number of primary sites for which effective and specific forms of systemic treatment are available.

Adenocarcinoma↗
PubMed1986

Transferrin receptor cycling by human lymphoid cells: lack of effect from inhibition of microtubule assembly.

Flow cytometry was used to follow the uptake and release of fluorescein-conjugated ferro-transferrin by CCRF-CEM human T - leukaemia cells on an individual cell basis. Pretreatment with the stathmokinetic agent vincristine for 5 hr had no effects on the cycling of transferrin, although microscopic examination of the cells showed a substantial proportion to be arrested in metaphase with cytoplasmic dispersal of tubulin, indicating inhibition of microtubule assembly. Tubulin is therefore unlikely to play a major role in the transferrin cycle of exponentially-growing cells, despite earlier reports that the cytoskeleton is involved in receptor clustering and down regulation.

Cell Cycle↗
PubMed1985

Application of DNA flow cytometry to paraffin-embedded archival material for the study of aneuploidy and its clinical significance.

By using a recently developed flow cytometric method we have analyzed cellular DNA content of paraffin-embedded histological material from cancer patients. This method allows the retrospective study of tumors from patients whose clinical outcome is already known, and we have applied it to ovarian cancers, stage II breast cancers, and to metastatic adenocarcinoma of unknown primary site. In addition to knowledge of patient survival, comprehensive information was available about other prognostic determinants and treatment received, and we have used multivariate analysis in an attempt to determine the prognostic significance of cellular DNA content. In ovarian cancer, it is a major prognostic variable except in stage IV disease, whereas in metastatic adenocarcinoma of unknown primary site cellular DNA content has no influence on survival. For stage II breast cancer the situation is more complex and requires larger numbers to be studied. However, aneuploid tumors tend to have more extensive involvement of axillary lymph nodes and a poorer overall disease-free survival. This influence of DNA content on disease-free survival appears to be confined to premenopausal patients, and has no effect on patient survival following disease recurrence. Although we need to study more patients and more tumor types, taken together the results so far show a generally more favorable prognosis for patients with diploid tumors, except in the presence of recurrent or metastatic disease. The better prognosis associated with diploid tumors could be due to the fact that they are more commonly found in earlier clinical stages rather than to their being inherently less aggressive than aneuploid tumors.

Aneuploidy↗
PubMed1985

Lack of correlations between plasma concentration of medroxyprogesterone acetate, hypothalamic-pituitary function, and tumour response in patients with advanced breast cancer.

Plasma medroxyprogesterone acetate (MPA) concentrations were measured in 61 patients with advanced breast cancer, after 3 weeks' treatment using 200 mg PO 8-hourly, to determine whether the previously reported wide interpatient variations correlated with tumour response or toxicity. Seventeen patients (28%) responded to the drug, and their mean plasma MPA concentration was 97 ng/ml +/- 68 SD, compared with 115 ng/ml +/- 87 SD for the patients whose disease progressed. Side-effects attributed to MPA were seen in 18 patients, who had a mean drug concentration of 113 ng/ml +/- 104 SD. This was not significantly higher than that of the patients who did not experience drug toxicity. Because of a suggestion that some of the antitumour activity of the drug could be mediated via an effect on the hypothalamic-pituitary axis, we also measured plasma FSH, LH, and prolactin concentrations after the 3-week treatment with MPA, but found no correlations with either drug concentration or tumour response. These results indicate that with the present treatment schedule the monitoring of plasma MPA concentrations has no role in routine practice and suggest that the inherent sensitivity of the tumour to progesterone is probably the major determinant of response.

Adult↗
PubMed1985

Cell cycle effects of iron depletion on T-47D human breast cancer cells.

T-47D human breast cancer cells grown in culture medium containing low concentrations of fetal calf serum (FCS) proliferated very slowly, with an accumulation of cells in the G2 phase of the cell cycle, increased polyploid cells, and increased expression of transferrin receptors. Cell proliferation was stimulated by the addition of human transferrin or ammonium ferric citrate to the medium. Growth inhibition and accumulation of G2-phase cells could also be produced in T-47D cells grown in medium containing 10% FCS by the addition of the iron chelator, desferrioxamine. It is concluded that cellular deprivation of iron and/or transferrin is the major cause of reduced proliferation rates and G2-phase arrest which accompany the culture of these cells in medium supplemented with low concentrations of FCS.

Animals↗
PubMed1985

Metastatic adenocarcinoma of unknown primary site: abnormalities of cellular DNA content and survival.

Using a new flow cytometric technique we measured the cellular DNA content of tumour biopsies taken from 152 patients presenting with metastatic adenocarcinoma or undifferentiated carcinoma of unknown primary site. One hundred and six (70%) contained populations of cells with an abnormal cellular DNA content and the remainder were diploid. The incidence of aneuploidy was similar for the two sexes and bore no obvious relationship to the various patterns of metastatic involvement. Median survival of patients with diploid tumours was 4.2 months and for patients with aneuploid tumours, 4.8 months. Nine of the 46 patients with diploid tumours (i.e. 18%) survived for more than 2 yr compared to 10 of 106 (9%) of those with aneuploid tumours. These results indicate that the incidence of aneuploidy in this heterogeneous group of patients is similar to that reported for adenocarcinomas of known histogenesis, such as breast or colorectal cancer. In contrast to many of these tumour types, however, patients with metastatic adenocarcinomas of unknown primary which are diploid do not on the whole have a more favourable prognosis.

Adenocarcinoma↗