Search PubMed⌕ Search

Biomedical subjects

B Drewinko

Publications and source records attributed to B Drewinko.

At least 37 records · Page 2Linked to original sources
PubMed1986

Kinetics and mechanism of the 1-beta-D-arabinofuranosylcytosine-induced potentiation of cis-diamminedichloroplatinum(II) cytotoxicity.

Certain aspects of the potentiation induced by 1-beta-D-arabinofuranosylcytosine (ara-C) on cis-diamminedichloroplatinum(II) (cis-DDP) cytotoxicity were investigated. The time dependency of additions of ara-C and cis-DDP was established by allowing cells to grow for various intervals in fresh medium following the removal of one agent before adding the second one. ara-C had no potentiating effect on cis-DDP toxicity when given to the cells before the addition of cis-DDP. When the experiment was reversed so that cis-DDP was added first and ara-C second, a slight potentiating effect was observed even if the drugs were added 4 h apart. The optimal toxic effect was obtained when ara-C and cis-DDP were added together. Continuous exposure of cells to concentrations of ara-C and cis-DDP 10 times lower than those used in pulse treatment experiments resulted in an additive rather than a synergistic effect. ara-C, unable to kill cells in pulse treatment, killed 96% of the cells after 24 h of continuous incubation. Thiourea was able to prevent the cytotoxic effect of cis-DDP in a concentration-dependent manner when given to the cells immediately following their treatment with cis-DDP; at 0.1 M thiourea, the cytotoxic effect of cis-DDP was almost completely prevented. Similar results were obtained when the cells were exposed to a combination of cis-DDP and ara-C. In this case, 0.1 M thiourea resulted in over 80% survival of cells treated with the drug combination. Thiourea had to be added to the cells either together with cis-DDP or immediately following removal of the drug in order to completely prevent the cytotoxic effect. A similar time factor was involved when cells were treated with a combination of cis-DDP and ara-C before their exposure to thiourea, but in this case thiourea was only able to prevent completely the cytotoxic effect when added simultaneously with the drug combination. In other experiments, the effect of thiourea on cis-DDP-induced DNA cross-linking was measured by the alkaline elution technique. Thiourea was capable of preventing DNA cross-link formation both in cells treated with cis-DDP alone, and in cells exposed to the combination of cis-DDP and ara-C These observations further support the contention that ara-C potentiates cis-DDP cytotoxicity by increasing the ability of the platinum compound to form earlier, more stable DNA cross-links regardless of whether it is present in free or monoadducted form.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell Line↗
PubMed1986

Successful heterotransplantation of human colon cancer cells to athymic animals is related to tumor cell differentiation and growth kinetics and to host natural killer cell activity.

Six established human colon carcinoma cell lines with distinct degrees of cell differentiation were inoculated into infant (less than 4 weeks) and adult (greater than 8 weeks) nude rats. The most differentiated tumor cells (group I) had nearly a 100% rate of tumor takes whether inoculated subcutaneously, intraperitoneally, or intracerebrally into adult rats; subcutaneous growth continued unabated for a 120-day observation period. Cells with intermediate differentiation (group II) had nearly an 80% incidence in tumor takes when injected subcutaneously and 14-60% when injected intraperitoneally. Subcutaneous growth continued only for about 30 days, after which time growth declined, and tumors regressed completely. Intracerebral inoculations of group II cells resulted in 64-83% tumor takes. Subcutaneous injections of cells from groups I and II into 5- to 10-day-old rats resulted in 100% tumor takes; tumors induced by group II did not regress, and after about 60 days reached volumes comparable to those originated by cells from group I. No tumors developed when cells from group III (undifferentiated) were injected either subcutaneously or intraperitoneally (and even intravenously) into adult rats. Only when the intracerebral route was employed was there a 60-71% incidence of tumor takes. Also, for one of the cell lines in this group, subcutaneous injection into infant rats resulted in 100% tumor takes. NK cell activity of infant rats against all of the colon cells (measured by the 51Cr release assay) was negligible; in adult rats, the activity varied according to the cell type, being usually highest against the less differentiated tumors. Our data on the incidence of tumor takes, and on the dynamics of tumor growth and decline suggest that successful heterotransplantation of human colon carcinoma cells into nude rats depends on the activity of host NK cells. In turn, this activity seems related to the degree of cell differentiation and the growth kinetics of the xenografted tumor cells. These observations highlight important differences in biological characteristics of human colon carcinoma with important implications for their intrinsic ability to grow and metastasize, and, possibly, their response to biological response modifiers.

Age Factors↗
PubMed1985

The human tumor stem cell assay revisited.

The human tumor stem cell assay (HTSCA) is a bilayer soft agar system for growing fresh human tumor specimens in vitro to determine drug sensitivity and improve our understanding of tumor biology. Recent clinical correlations of 60% accuracy for predicting a positive clinical response and a 90% accuracy for predicting a lack of response to therapeutic agents suggest promising clinical usefulness. However, the clinician should be aware of the assay's inherent pitfalls, such as heterogeneity of the tumor specimen, inability to obtain pure single-cell suspensions, low cloning efficiency, unusual drug dose-dependent survival curves, uncertain validity of in vitro pharmacology, non-standardized criteria for in vitro sensitivity, and the variability of in vitro results. A brief summary of the concepts, potential, and limitations of this assay are discussed.

Animals↗
PubMed1985

Effects and interactions of epidermal growth factor, insulin, hydrocortisone, and estradiol on the cloning of human tumor cells.

We investigated the effects and interactions of epidermal growth factor (EGF), insulin, hydrocortisone, and estradiol on the growth of 18 freshly obtained human tumors in our human tumor stem cell assay (HTSCA) cultured at a reduced serum concentration (8.5% ml). All possible combinations of these four supplement factors were added to the assay to determine the ability of each component to enhance colony formation. We found that hydrocortisone was the most effective single supplement in stimulating colony growth in the HTSCA. Supplementation with insulin, estradiol, or both had some growth-promoting effect but not as great as hydrocortisone. Moreover, the addition of insulin, estradiol, or both often demonstrated a negative interaction with hydrocortisone. EGF supplementation alone; in dual combination with insulin, estradiol, or hydrocortisone; or in combination with estradiol and insulin in the assay did not significantly increase colony formation. However, EGF added to the cultures containing hydrocortisone with insulin and/or estradiol significantly increased colony formation and reversed the negative effect of insulin and estradiol on hydrocortisone activity. Thus, under conditions of our assay, the most effective combination in promoting colony growth contained all four factors.

Cell Division↗
PubMed1985

Comparative cytotoxicity between cisplatin and second generation platinum analogs.

The cytotoxic activity of cis-DDP and four second generation platinum coordination complexes (TNO-6; JM-82; JM-8; and JM-9) was compared on six established human colon carcinoma cell lines with different degrees of differentiation. Cytotoxicity was evaluated by the inhibition of colony formation technique. Cis-DDP was uniformily active against all lines. JM-8 and JM-9 were virtually ineffective for all cell lines, even at concentrations as high as 50 micrograms/ml. JM-82 was slightly more active although (with the exception of LoVo cells) still about 10-fold less efficacious than cis-DDP. TNO-6 was the only derivative with appreciable cytotoxic activity although about 2 to 5-fold less than cis-DDP for lines SW48, 620, 480, and 1116. For LoVo and SW403, TNO-6 was slightly more active than cis-DDP. In both such instances, increased efficacy resulted from abrogation of the shoulder region of the survival curve while the slope remained essentially intact. Thus any enhancement in therapeutic efficacy with these second generation analogues can only be expected from possible decreases in toxic effects but not from superior tumor cell kill activity.

Antineoplastic Agents↗
PubMed1985

Survival of human bone marrow cells after in vitro treatment with 12 anticancer drugs and implications for tumor drug sensitivity assays.

We investigated the responsiveness of human normal granulocyte-macrophage colony-forming units in culture (GM-CFUC) continuously exposed in vitro to 1 of 12 anticancer drugs. All drugs except bleomycin showed a simple negative exponential dose-survival curve. The in vitro toxicity of drugs in GM-CFUC did not always correlate with the relative myelosuppressive potency observed in vivo. In addition, tumor specimens from 38 patients mainly with ovarian cancer were cultured in a human tumor colony-forming assay and continuously exposed to drugs at low, intermediate, and high concentrations capable of killing 40%, 78%, and 99% of GM-CFUC, respectively. The most active drugs were cis-platinum, velban, 5-fluorouracil, and 5-fluoro-ara-AMP. Dose-survival curves of bone marrow progenitor cells may serve as an in vitro reference system for selecting appropriate drug concentrations of myelosuppressive drugs in drug-sensitivity assays of human tumors.

Antineoplastic Agents↗
PubMed1985

Regulation of breast tumor growth by high dose estrogen is independent of the presence of estrogen receptors.

17 beta-estradiol stimulated the clonogenic growth of four established human breast tumor cell lines independent of the estrogen receptor status of the cells. Likewise, tamoxifen citrate, a nonsteroidal antiestrogen, inhibited the in vitro growth of both estrogen receptor-negative and estrogen receptor-positive cell lines to a similar degree. These findings indicate that, at pharmacologic doses, the growth stimulatory and inhibitory effects of estrogen and antiestrogens are not necessarily mediated by hormone-specific receptors.

Breast Neoplasms↗
PubMed1985

Estrogen induced expansion of the growth fraction in receptor negative human breast cancer.

The feasibility of a cytokinetic chemotherapy based on estrogenic recruitment has been evaluated in 5 patients, affected by locally advanced breast cancer with low or absent receptor content. Tumor proliferative activity was evaluated by the thymidine labeling index (TLI) and the primer-dependent alpha DNA polymerase assay (PDP-LI) which gives an in vitro estimation of tumor growth fraction. The patients have been treated with diethylstilbestrol (DES) 1 mg/die. for 3 days, followed by FAC (5-Fluorouracil 600 mg/m2, Adriamycin 50 mg/m2, Cytoxan 600 mg/m2) i.v. on day 4 q. 21 days. Radical surgery was performed after 3 DES-FAC regimens. Tumor biopsies for evaluation of tumor proliferative activity were performed immediately before and after DES and 24 h after chemotherapy. Our results demonstrate that DES was able to induce an increase in TLI in 3/5 of the patients while the PDP-LI was significantly increased in 5/5 of the patients; subsequent chemotherapy induced a sharp decrease in tumor proliferation. These results provide the rationale for the design of cytokinetic regimens where chemotherapy is administered at the time of estrogen induced tumor cell recruitment.

Breast Neoplasms↗
PubMed1985

The synergistic lethal interaction of cis-diamminedichloroplatinum and natural nucleosides is related to increased DNA cross-links.

Human tumor cells were treated in vitro with combinations of cis- or trans-dichlodiammineplatinum (DDP) and natural nucleosides (thymidine, uridine, cytidine and adenosine). Effects were measured by inhibition of colony-formation (cell survival) and DNA alkaline elution (DNA cross-links). No increments in cell lethality or DNA cross-links were elicited by any combination of trans-DDP and nucleosides. In contrast, every combination of cis-DDP and nucleoside was eminently synergistic with 5- and 10-fold increases in cell lethality over the predicted sum of each agent alone. These increments in cell kill correlated linearly with increases in DNA crosslinks suggesting that the nucleosides interact with cis-DDP to enhance its cytotoxic crosslinking mode of action.

Adenosine↗
PubMed1985

Comparative sensitivity of different methods to detect and quantify circulating fibrinogen/fibrin split products.

This study compared the sensitivity of three methods: staphyloccocal clumping test, SCT (Sigma and Calbiochem-Behring, CBC, reagents); Thrombo-Wellcotest (TWT); and Dade fibrinogen degradation products detection set, to quantify fibrinogen/fibrin split products (FSP) in blood samples from 696 patients and 124 normal donors using fibrinogen as the reference value. The Dade method gave quantitative results closely approaching the stated amount of fibrinogen. The SCT using Sigma reagents gave higher "fibrinogen" values, while the CBC reagents gave markedly lower "fibrinogen" values. The TWT detected only 25% of the fibrinogen standard. Detection of FSP following plasmin digestion of fibrinogen varied considerably for each test. The TWT, insensitive to most of the native fibrinogen, detected most of the FSP following only 15 minutes of plasmin digestion. In contrast, both assays relying on the SCT were completely negative after 24 hours of plasmin digestion. All four methods yielded FSP titers of less than 10 micrograms/mL in 97 (78.2%) of 124 blood samples from normal donors. The SCT Sigma reagents consistently gave results of less than 10 micrograms/mL in all normal donors. No instance of an FSP value greater than 40 micrograms/mL was noted for the 124 normal donors. Of the 696 patient blood samples tested, the Dade assay gave the highest or equally highest (with respect to another FSP method) value in 604 (87%) cases; the Sigma SCT did so in 360 (52%); the TWT in 316 (45%); and the CBC assay in 184 (26%) cases. The Dade test classified the largest number of blood samples, 328 (47.1%), in the greater than 10 less than 40 micrograms/mL titer category; however, the proportion of cases (32.2%) in which this test yielded values greater than 40 micrograms/mL was about the same as those produced by the Sigma SCT (29.9%) and TWT products (25.8%). Thus, with the exception of the normal (less than 10 micrograms/mL) and the suspicious (10-40 micrograms/mL) range, all three methods (Dade, Sigma, and TWT) are comparable in their abilities to detect abnormal levels of FSP. In the normal range, the Dade method will yield results that are frequently in the suspicious range. The CBC was noticeably inferior in detecting both suspicious and frankly abnormal values of FSP. Eight patients with acute leukemia were monitored sequentially with FSP and fibrinopeptide A (FpA) assays during their first course of chemotherapy. In all instances, elevated FpA levels correlated with elevated FSP values, as determined by the Dade, Sigma, or TWT assays.(ABSTRACT TRUNCATED AT 400 WORDS)

Agglutination Tests↗
PubMed1985

Tamoxifen-citrate counteracts the antitumor effects of cytotoxic drugs in vitro.

Hormones and cytotoxic drugs are often combined in the treatment of patients with breast carcinoma to broaden the antitumor spectrum of the therapy. We found that, in vitro, the most commonly used endocrine agent, tamoxifen citrate, attenuates the cytotoxic potential of 5-fluorouracil (5-FU) and of doxorubicin. The effect was observed on estrogen receptor positive and on estrogen receptor negative breast tumor cells. Combinations of growth inhibitory hormones and cytotoxic drugs may therefore be counter-productive. For the treatment of hormone-independent tumors they may even be harmful since in these tumors tamoxifen exerts no independent cell kill that compensates for its modifying effect on the cytotoxicity of drugs.

Animals↗
PubMed1985

Full expression of blood group-related, transplantation-related, and carcinoembryonic antigens in human colorectal cancer cells with different degrees of phenotypic differentiation.

Seven established human colon carcinoma cell lines with distinct degrees of phenotypic differentiation were evaluated for the presence of blood group-related and transplantation-related antigens in relation to their production of carcinoembryonic antigen (CEA). All lines presented A and B antigens regardless of the patients' original red blood cell type. However, tumor cells from patients originally classified as O-type had lower expression of both A and B antigens and high production of CEA. Cells from patients with an original A type had low to undetectable CEA production and high expression of both A and B antigens. There was no particular segregation of transplantation-related antigens with respect to phenotypic expression. All lines presented HLA-A, -B, and -C, as well as -DR antigens. These results demonstrate that colon carcinoma cells have the ability to fully express both blood group-related and transplantation-related antigens, even if discordant with the donor's red blood cell phenotype. Furthermore, it appears that expression of A antigen is intimately related to synthesis of CEA.

ABO Blood-Group System↗
PubMed1985

Cytotoxic efficacy of reconstituted and stored antitumor agents.

The stability of the cell-killing efficacy of 10 antitumor drugs stored at different temperatures and concentrations was evaluated on an established human colon carcinoma cell line using the colony formation technique. Drugs were reconstituted in the appropriate solvent, further diluted in 0.9% NaCl solution to obtain the desired storage concentration, and stored at 4 degrees C, -20 degrees C, and -70 degrees C for periods of up to 3 weeks. Cytotoxic efficacy was tested weekly by exposing the cells to the final drug dilution for 1 h at 37 degrees C. Stability of cytotoxic potency depended on the particular drug, and the duration, concentration, and temperature of storage but, in general, most drugs remained efficacious only within limited periods of time (at most, 2 weeks). These results suggest that the conditions of drug storage following reconstitution are critical factors with respect to lethal efficacy. Therefore, analysis of in vitro cytotoxic efficacy can be meaningful only when storage conditions are specified in order to avoid false-negative results in the human tumor clonogenic assay.

Antineoplastic Agents↗
PubMed1985

Growth kinetics of human colorectal carcinoma.

In this study, we investigated the influence of some of the variables of the thymidine labeling index (TLI) in human colorectal carcinoma. These variables were: cell suspensions versus tissue fragments; incubation with 5-fluoro-2'-deoxyuridine; method of tissue procurement; location in the large bowel; and TLI distribution in different areas of the tumor. Mean TLI values for cell suspensions and tissue fragments were 3.4 (range, 0.1 to 7) and 1 (0.1 to 2.6), respectively. Incubation with 5-fluoro-2'-deoxyuridine significantly reduced tritiated thymidine incorporation. There were no differences in TLI values between biopsy and surgical samples and in different areas of the large intestine. Median TLI of cell suspensions in 47 tumors was 2.25 (0.1 to 10.1). These results show that the TLI of colorectal carcinoma is low and correlates with its slow growth. Cell suspension provides a more representative and unbiased sample than tissue fragments in cell kinetics studies.

Adenocarcinoma↗
PubMed1985

Mixed function oxidase activities of established human colon carcinoma cell lines in the activation of cyclophosphamide.

Three established human colon carcinoma cell lines (LoVo, SW620, and SW403) with different degrees of phenotype differentiation were investigated for their sensitivity to the cytotoxic effects of cyclophosphamide (CP) and to its active metabolite, 4-hydroxycyclophosphamide (4-OH-CP), and for their mixed function oxidase (MFO) activities. None of the cell lines showed sensitivity to CP as determined by the inhibition of colony formation assay, even after continuous drug treatment at high concentrations (200 microgram/ml) for up to 72 h. CP also had no effect on the cellular doubling time or on the incorporation of [3H]-thymidine. Pretreatment with phenobarbital (PB) plus hydrocortisone (HC) was unable to induce CP cytotoxicity. In contrast, 4-OH-CP, the major metabolite formed from CP by MFO, was highly toxic to the cells. About 90% cell kill was obtained at drug concentrations of 17.5 microgram/ml (LoVo), 15 microgram/ml (SW620), and 55 microgram/ml (SW403) after 1-h incubation at 37 degrees. MFO activities were determined by measuring p-nitroanisole demethylase (PNAD) and arylhydrocarbon hydroxylase (AHH) in microsomes prepared from noninduced cells or from cells treated with benzanthracene or PB plus HC. Intrinsic AHH activities were below the level of detection for all cell lines [less than 1 pmol of 3-hydroxybenzo(a)pyrene (3-OH-BP) formed per min per mg of protein]. Treatment with benzanthracene resulted in AHH activities of 12 to 15 pmol of 3-OH-BP per min per mg of protein, but treatment with PB plus HC failed to induce significant AHH activities. PNAD activities in noninduced cells as well as in cells treated with benzanthracene were 0.05 to 0.08 nmol of p-nitrophenol formed per min per mg of protein; treatment with PB plus HC increased PNAD activities by only 1.5-fold. Thus, in contrast to reports for rat colon and for a single human colon cancer cell line, CP is inactive when applied directly to several other human colon carcinoma cell lines. Because these cells have minimally detectable intrinsic and induced MFO activities, we conclude that CP cannot be successfully metabolized into 4-OH-CP to induce a significant degree of cell kill.

Aryl Hydrocarbon Hydroxylases↗
PubMed1985

Chemotherapy following estrogen-induced expansion of the growth fraction of human breast cancer.

We have evaluated the feasibility of a cytokinetically oriented regimen based on the induction of cell recruitment by diethylstilbestrol (DES) in locally advanced human breast cancer. Tumor proliferative activity was evaluated by the thymidine labeling index and the primer-dependent alpha-DNA polymerase labeling index, which gives an in vitro estimation of the growth fraction. Sixteen previously untreated patients received DES (1 mg daily for 3 days) followed by FAC [5-fluorouracil (600 mg/m2): Adriamycin (50 mg/m2): Cytoxan (600 mg/m2)] i.v. on day 4 every 21 days. Radical surgery was delayed to allow for three DES-FAC regimens in responsive patients. Proliferative activity on tumor biopsies was evaluated immediately before and after treatment with DES, 24 h after chemotherapy and, in nine patients, at the time of radical surgery. DES was able to induce a significant increase in thymidine labeling index in 8 of 16 patients, while the primer-dependent alpha-DNA polymerase labeling index was significantly increased in 13 of 16 tumors, independently of their estrogen receptor content. Subsequently administered chemotherapy induced an early decrease in tumor proliferation. In the nine patients submitted to surgery after three DES plus FAC courses, the average thymidine labeling index and primer-dependent alpha-DNA polymerase labeling index were 27.8 and 73% of the pretreatment values. Our preliminary results provide the rationale for the design of new therapeutic schemes in which antitumor drugs are given at the time of estrogen-induced tumor cell recruitment. Further extended studies are required to establish whether induction of tumor cell recruitment will actually translate into appreciable improvement of the clinical response to chemotherapy.

Adult↗