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Biomedical subjects

J K Willson

Publications and source records attributed to J K Willson.

At least 73 records · Page 4Linked to original sources
PubMed1993

Synergistic efficacy of O6-benzylguanine and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) in a human colon cancer xenograft completely resistant to BCNU alone.

The DNA repair protein O6-alkylguanine-DNA alkyltransferase (alkyltransferase) repairs cytotoxic DNA damage formed by 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). High levels of this repair protein cause tumor drug resistance to nitrosoureas. To investigate the ability of a direct alkyltransferase inhibitor, O6-benzylguanine, to reverse the nitrosourea resistance of human colon cancer cells, we studied the VACO 6 cell line which has high alkyltransferase and is completely resistant to BCNU at maximal tolerated doses in the xenograft model. O6-Benzylguanine at 0.5 microgram/mL for 1 hr inactivated VACO 6 alkyltransferase by > 98% and reduced the IC50 of BCNU by 3- to 4-fold. Further analysis indicated that these two agents act in a highly synergistic fashion. In xenograft bearing athymic mice, dose-dependent depletion of hepatic and tumor alkyltransferase was noted. To maintain alkyltransferase depletion in the xenograft for at least 24 hr, two doses of 60 mg/kg O6-benzylguanine were given 1 hr prior and 7 hr after BCNU. Under these conditions, VACO 6 xenografts became responsive to BCNU with significant reductions (P < 0.001) in the tumor growth rate. The combination increased toxicity to the host, reducing the maximum tolerated dose of BCNU by approximately 50%. This study provides definitive evidence that high alkyltransferase activity is responsible for BCNU resistance in human colon cancer xenografts and that with careful drug scheduling, O6-benzylguanine can sensitize a tumor which is completely unresponsive to BCNU alone. Further studies which optimize the therapeutic index of BCNU and O6-benzylguanine in vivo will define the schedule to be used in broader preclinical studies.

Alkyl and Aryl Transferases↗
PubMed1993

Autocrine transforming growth factor-alpha is associated with progression of transformed properties in human colon cancer cells.

The GEO colon carcinoma cell line is weakly tumorigenic in athymic mice and shows differentiated properties both in tissue culture and in xenografts. Proliferating monolayer cultures of GEO cells which normally require exogenous epidermal growth factor (EGF) for optimal growth displayed a marked inhibition in growth upon addition of antibodies that block binding to the EGF receptor or neutralize TGF-alpha. These results indicated that GEO cells utilize TGF-alpha in a weak autocrine loop. The availability of a weakly malignant model system in which TGF-alpha had demonstrable, but low level autocrine activity, permitted the investigation of the role of TGF-alpha in tumorigenesis by generating a stronger autocrine loop through the overexpression of the polypeptide. GEO cells were electroporated with an expression vector containing the human TGF-alpha cDNA, and stable clones were isolated that constitutively expressed the TGF-alpha cDNA in a strong autocrine loop. However, the growth rate of the parental cells in EGF-supplemented medium was the same as that of transfected cells with or without growth factor-supplemented medium. Thus, any biological changes generated by the overexpression of TGF-alpha were due to the autocrine nature of the growth mechanism rather than due to any decrease in doubling time leading to a faster growth rate. Transfected GEO cells showed an increase in anchorage-independent growth and formed tumors more readily in athymic nude mice indicating that TGF-alpha plays a role in progression of transformed properties.

Animals↗
PubMed1993

Phase II multicenter evaluation of prolonged murine monoclonal antibody 17-1A therapy in pancreatic carcinoma.

Twenty-eight patients with unresectable, measurable pancreatic carcinoma and Eastern Oncology Cooperative Group (ECOG) performance status of 0 or 1 were treated with the murine monoclonal antibody 17-1A, planning to administer 500 mg i.v. three times weekly for 8 weeks. Treatment was well tolerated, with an 18% incidence (five patients) of hypersensitivity reactions. All hypersensitivity episodes occurred in the first 3 weeks of therapy and required treatment discontinuation. Six patients required early discontinuation of therapy due to symptomatic progressive disease and one patient was removed from the study due to a protocol violation. Sixteen patients received the full course of 12 g of antibody. One patient has exhibited a durable partial response. Antibody pharmacokinetics were determined in five patients. In four patients peak 17-1A levels averaged 100 micrograms/ml with mean harmonic t1/2 of 16.8 h in a one-compartment model. Neither pretreatment nor posttreatment levels of circulating 17-1A changed significantly during the 8 weeks of treatment. This study demonstrates the feasibility and acceptable toxicity of repetitive dosing with an unconjugated murine monoclonal antibody. The lack of efficacy of treatment suggests that factors other than prolonged exposure of tumor and cytotoxic effector cells to murine antibody are required for successful antibody therapy of pancreatic cancer.

Aged↗
PubMed1993

Repression of autocrine transforming growth factor beta 1 and beta 2 in quiescent CBS colon carcinoma cells leads to progression of tumorigenic properties.

Previous work has shown that repression of negative autocrine transforming growth factor (TGF) beta 1 did not alter the growth rate of a human colon carcinoma cell line, but the time required for the cells to enter exponential growth from lag phase was reduced (S. P. Wu, D. Theodorescu, R. Kerbel, J. K. V. Willson, K. M. Mulder, L. E. Humphrey, and M. G. Brattain, J. Cell Biol., 116: 187-196, 1992). These results have led to the hypothesis that the tumor suppressive activity of autocrine TGF-beta 1 was directed at quiescent nondividing cells rather than actively dividing cells. In order to test this hypothesis, a weakly tumorigenic, well-differentiated human colon carcinoma cell line designated CBS, which expressed autocrine TGF-beta 1 and -beta 2 activity in quiescent cells, but not in exponential growth phase cells, was identified. This cell line was stably transfected with a full-length TGF-beta 1 antisense complementary DNA. Constitutive expression of TGF-beta 1 antisense mRNA in CBS cells resulted in repression of autocrine TGF-beta 1 and -beta 2 protein activity in quiescent cells of approximately 10-fold. TGF-beta 2 repression could have been due to interaction with TGF-beta 1 antisense mRNA, since these two isoforms have a high degree of homology, or it could have been indirectly due to TGF-beta 1 repression, since this isoform has been shown to affect transcriptional and posttranscriptional control of TGF-beta 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1992

Modulation of nitrosourea resistance in human colon cancer by O6-methylguanine.

Human colon cancer is resistant to a variety of alkylating agents including the nitrosoureas. To specifically evaluate nitrosourea resistance, we studied the role of O6-alkylguanine-DNA alkyltransferase (alkyltransferase) which is known to repair nitrosourea-induced cytotoxic DNA damage. Alkyltransferase activity varied over a similar wide range in 25 colon cancer biopsies and 14 colon cancer cell lines but the activity was not correlated with differentiation status, Dukes' classification or in vitro growth characteristics. 1,3-Bis-(2-chloroethyl)-1-nitrosourea (BCNU) resistance and alkyltransferase activity were highly correlated (R2 = 0.929, P less than 0.001) in 7 different colon cancer cell lines, suggesting that the alkyltransferase is an important component of nitrosourea resistance in colon cancer cells. In the BCNU-resistant, high alkyltransferase VACO 6 cell line, inactivation of the alkyltransferase by O6-methylguanine caused a proportional decrease in the BCNU IC50, consistent with that predicted by the regression line. Enzyme inactivation was also associated with a marked increase in DNA cross-link formation. Because alkyltransferase correlates with BCNU resistance in colon cancer, and resistance can be reversed by inactivating the protein, the alkyltransferase may have an important role in nitrosourea resistance in human colon cancer cells. These data provide the rationale for clinical trials in colon cancer with biochemical modulators of the alkyltransferase to increase the therapeutic response to nitrosoureas.

Carmustine↗
PubMed1992

Using toxicity grades in the design and analysis of cancer phase I clinical trials.

Ethical considerations in a cancer phase I trial require a design allowing determination of the maximum tolerated dose with a minimum number of patients treated at low ineffectual or high overly toxic doses. It would also be advantageous to complete the phase I trial in as short a period of time and with as few patients as possible to allow further resources for later studies in which patients are treated at the optimal dose. Several dose escalation schemes are compared. These are the Fibonacci, two two-stage schemes, and a proposed scheme which uses knowledge of all toxicity grades. Estimates of the maximum tolerated dose are obtained and compared using the dose escalation schemes alone, a logit model, and a proposed mean response model. Confidence intervals using the delta method are obtained from the logit and mean response models. The proposed scheme and the two-stage schemes have the advantage of requiring fewer patients, particularly at low doses. Confidence intervals obtained from the mean response model have better coverage than those from the logit model. Data from a cancer phase I trial of dipyridamole and acivicin is presented to illustrate the methods.

Antineoplastic Agents↗
PubMed1992

TGF-beta 1 is an autocrine-negative growth regulator of human colon carcinoma FET cells in vivo as revealed by transfection of an antisense expression vector.

Transforming growth factor-beta 1 (TGF-beta 1) has previously been implicated as a potential negative autocrine or paracrine growth regulator of certain cell types (Arteaga, C. L., R. J. Coffey, Jr., T. C. Dugger, C. M. McCutchen, H. L. Moses, and R. M. Lyons. 1990. Cell Growth & Differ. 1:367-374; Hafez, M. M., D. Infante, S. Winawer, and E. Friedman. 1990. Cell Growth & Differ. 1:617-626; Glick, A. B., K. C. Flanders, D. Danielpour, S. H. Yuspa, and M. B. Sporn. 1989. Cell Regulation. 1:87-97). This is based mainly on experiments assessing the effects of exogenous TGF-beta 1 or neutralizing antibodies to TGF-beta 1 on normal or tumor cell proliferation in vitro. However, direct evidence demonstrating such a negative regulation of tumor cell growth in vivo is still lacking. To overcome this problem we have constructed and used an antisense expression vector for TGF-beta 1 as a means of regulating endogenous TGF-beta 1 expression in tumor cells. Antisense-transfected FET human colon carcinoma cells showed a fivefold reduction in TGF-beta 1 mRNA and 15-fold reduction in TGF-beta 1 secretion. Antisense mRNA was detected in transfected cells by an RNase protection assay. Compared to control cells, cultured antisense-transfected cells showed a reduction in lag phase time rather than a change in doubling time. Cloning efficiencies of transfected cells were four times greater than control cells in anchorage-independent assays. Control cells did not form tumors at 5 x 10(5) in athymic nude mice. Antisense-transfected cells formed tumors in 40% of animals injected. At higher inocula (1 x 10(6) cells) antisense-transfected cells formed tumors in 100% of animals injected, but control cells still failed to form tumors. These results show that TGF-beta 1 acts as a negative growth regulator of human colon carcinoma cells in vivo as well as in vitro. Acquisition of partial or full resistance to such inhibitory effects may therefore contribute to tumor development and progression.

Animals↗
PubMed1991

Induction of nm23 gene expression in human colonic neoplasms and equal expression in colon tumors of high and low metastatic potential.

Levels of expression of the murine nm23 gene inversely correlate with metastatic potential in several rodent tumor model systems. Expression of the human nm23 homologue also is lower in human breast cancers of high metastatic potential than in breast cancers of low metastatic potential. In the present study, we examined changes in nm23 expression during colon carcinogenesis as found in 18 matched pairs of normal and neoplastic human colon tissues. We found that a 0.8-kilo-base nm23 transcript was expressed in all samples of morphologically normal colon mucosa. In 16 of 18 colon neoplasms, nm23 expression was further increased in the neoplastic, compared with the morphologically normal, colon mucosa from the same individual. Expression of nm23 was elevated over normal mucosa in 3 of 3 polyps, in 2 of 3 nonmetastatic cancers, and in 11 of the 12 cancers that were metastatic at the initial presentation. The levels of nm23 expressed were similar in the 12 metastatic colon neoplasms and in the 6 colon neoplasms of lower clinical stage. In addition, nm23 expression was maintained in culture in each of 12 cell lines initiated from human colon neoplasms and did not differ between lines established from neoplasms of high or low metastatic capability. We concluded that nm23 was expressed in normal colon mucosa. Expression of nm23 increased during early stages of colon carcinogenesis and remained increased in metastatic colon cancer. Therefore, in the colon, tissue-specific events dissociate nm23 expression from loss of tumor metastatic competence.

Adenocarcinoma↗
PubMed1991

Pharmacokinetic and pharmacodynamic analysis of fluorouracil during 72-hour continuous infusion with and without dipyridamole.

During a phase I trial of 3-day simultaneous continuous intravenous infusions of varying doses of fluorouracil (5FUra) and 7.7 mg/kg/d of dipyridamole, we examined the relationships between 5FUra dose and steady-state plasma concentration (Css) and the percentage reduction in WBCs, as well as the percentage frequency of stomatitis. The 5FUra was administered at doses ranging from 185 mg/m2/d times three to 3,600 mg/m2/d times three. In 42 patients, 86 cycles of 5FUra plus dipyridamole and 28 cycles of 5FUra alone were analyzed. The Css of 5FUra varied even within the same dose level. When patients receiving the same 5FUra dose were considered, the interpatient coefficient of variation of 5FUra Css in cycles of 5FUra plus dipyridamole was 23% +/- 4.2%. For courses of 5FUra alone, the coefficient of variation of 5FUra was 15.6% +/- 6.5%. When the occurrence of any degree of stomatitis was related to the Css 5FUra, with patients grouped in cohorts of 2-mumol/L increments, the following equations accurately described the frequency of stomatitis: for 5FUra plus dipyridamole, percentage frequency of stomatitis = 100(1-e-0.114Css), r2 = 0.88; for 5FUra alone, percentage frequency stomatitis = 100(1-e0.122Css), r2 = 0.80. When 5FUra dose was substituted for Css, these relationships were as follows: percentage frequency of stomatitis = 100(1-e-0.00031 [dose]), r2 = 0.85; and percentage frequency of stomatitis = 100(1-e-0.00051 [dose]), r2 = 0.80. When the relationship between the percentage reduction in WBC and Css 5FUra was examined, statistically significant relationships were also apparent: for 5FUra plus dipyridamole, percentage reduction in WBC = 100(1-e-0.085Css), r2 = 0.46; for 5FUra alone, percentage reduction in WBC = 100(1-e-0.060Css), r2 = 0.61. When 5FUra dose was substituted for Css, these relatinships were as follows: percentage reduction in WBC = 100(1-e-0.00023 [dose]), r2 = 0.40; percentage reduction in WBC = 100(1-e-0.00024 [dose]), r2 = 0.65. The relationship between either Css 5FUra or dose 5FUra and either stomatitis or myelosuppression were also well described by the modified Hill equation (J Theor Biol 20:171-201, 1968). These analyses indicate that it should be possible to develop therapeutic regimens wherein 5FUra is administered to achieve a targeted Css determined by the risk and severity of toxicity deemed acceptable.

Bone Marrow Diseases↗
PubMed1990

p53 gene mutations occur in combination with 17p allelic deletions as late events in colorectal tumorigenesis.

Coordinate loss of one copy of the p53 gene and mutation of the remaining copy occur in colorectal carcinomas and in many other human malignancies. However, the prevalence of p53 gene mutations in carcinomas which maintain both parental copies of p53 has not previously been evaluated. Moreover, it is not known whether p53 gene mutations are limited to malignant tumors or whether they can also occur in benign neoplasms. To answer these questions, a total of 58 colorectal tumors have been examined; in each tumor, allelic losses were assessed using restriction fragment length polymorphisms and p53 gene mutations were assessed by sequencing cloned polymerase chain reaction products. The following conclusions emerged: (a) p53 gene mutations occurred but were relatively rare in adenomas, regardless of size and whether the adenomas were derived from patients with familial adenomatous polyposis; (b) In carcinomas as well as in adenomas, p53 gene mutations were infrequently observed in tumors which contain both copies of chromosome 17p (17% of 30 tumors), while tumors which lost one copy of chromosome 17p usually had a mutation in the remaining p53 allele (86% of 28 tumors); (c) p53 gene mutations were found at similar frequencies in primary tumor samples and in cell lines derived from tumors. These and other data suggest that the rate limiting step in p53 inactivation is point mutation and that once a mutation occurs, loss of the remaining wild-type allele rapidly follows. Both mutations and allelic losses generally occur near the transition from benign to malignant growth, and the p53 gene may play a causal role in this progression.

Adenoma↗
PubMed1990

Suppression of human colorectal carcinoma cell growth by wild-type p53.

Mutations of the p53 gene occur commonly in colorectal carcinomas and the wild-type p53 allele is often concomitantly deleted. These findings suggest that the wild-type gene may act as a suppressor of colorectal carcinoma cell growth. To test this hypothesis, wild-type or mutant human p53 genes were transfected into human colorectal carcinoma cell lines. Cells transfected with the wild-type gene formed colonies five- to tenfold less efficiently than those transfected with a mutant p53 gene. In those colonies that did form after wild-type gene transfection, the p53 sequences were found to be deleted or rearranged, or both, and no exogenous p53 messenger RNA expression was observed. In contrast, transfection with the wild-type gene had no apparent effect on the growth of epithelial cells derived from a benign colorectal tumor that had only wild-type p53 alleles. Immunocytochemical techniques demonstrated that carcinoma cells expressing the wild-type gene did not progress through the cell cycle, as evidenced by their failure to incorporate thymidine into DNA. These studies show that the wild-type gene can specifically suppress the growth of human colorectal carcinoma cells in vitro and that an in vivo-derived mutation resulting in a single conservative amino acid substitution in the p53 gene product abrogates this suppressive ability.

Cell Division↗
PubMed1990

Phase I trial of 5-fluorouracil and dipyridamole administered by seventy-two-hour concurrent continuous infusion.

Forty-seven patients with advanced malignancies were treated with a concurrent 72-h continuous infusion of 5-fluorouracil (FUra) and dipyridamole. The FUra dose was escalated over the dose range of 185 to 3600 mg/m2/day for 3 days. Dipyridamole was administered in a fixed dose of 7.7 mg/kg/day for 3 days. A total of 155 courses of therapy were completed of which there were 31 paired courses of the combination and FUra alone, at the same dose of FUra and in the same patient. This was for purposes of analysis of pharmacokinetics and modulation of FUra toxicity by dipyridamole. Stomatitis was the dose-limiting toxicity experienced by patients entered into this trial. Myelosuppression was not a serious problem. Increasing FUra plasma concentration was associated with greater leukopenia and stomatitis. Dipyridamole did not appear to modulate the systemic toxicity of FUra. The pharmacokinetics of FUra were altered by the concurrent administration of dipyridamole. Dipyridamole promoted the total body clearance of FUra which resulted in lower mean steady-state FUra plasma concentrations when compared with courses of FUra alone administered at the same dose level. These differences were statistically significant over the course of the trial. For courses of the combination, FUra exhibited linear pharmacokinetics over the dose range studied. Total body clearance of FUra declined slightly at the higher dose levels, but the differences were not significant. For courses of FUra alone, total body clearance was significantly decreased above the dose level of 2300 mg/m2/day. At the maximal tolerated dose of FUra, 2300 mg/m2/day x3, mean steady-state FUra plasma concentration and total body clearance were 6.6 microM and 122 liters/h/m2, respectively, for courses of the combination. The corresponding pharmacokinetic parameters were 7.4 microM and 103 liters/h/m2 for courses when FUra was given alone. Further evaluation of the utility of this regimen and basis of these pharmacokinetic observations appear warranted.

Adult↗
PubMed1990

Growth stimulation by coexpression of transforming growth factor-alpha and epidermal growth factor-receptor in normal and adenomatous human colon epithelium.

Autocrine stimulation of the epidermal growth factor receptor (EGF-R), by coexpression of transforming growth factor-alpha (TGF-alpha), causes malignant transformation of some fibroblast cell lines. TGF-alpha and EGF-R are both known to be expressed in colon carcinoma tissue and have been shown coexpressed in colon carcinoma cell lines. TGF-alpha autocrine activation of EGF-R has been suggested as a potential mechanism contributing to abnormal growth control in colon cancer. We now report coexpression of TGF-alpha and EGF-R transcripts in morphologically normal colonic epithelium from five individuals, in colonic adenomas from three individuals, and in a nontumorigenic colon adenoma cell line, VACO-330. Functional studies demonstrate VACO-330 growth is stimulated by exogenous TGF-alpha and is completely abolished by a blocking anti-EGF-R antibody. Autocrine stimulation of EGF-R by TGF-alpha is therefore required for growth of the adenoma cell line. Autocrine stimulation of EGF-R by TGF-alpha does not cause malignant transformation of the colonic epithelial cell. In normal and adenomatous human colon TGF-alpha, via either an autocrine or paracrine mechanism, is likely an important physiologic stimulant of epithelial proliferation.

Adenoma↗
PubMed1990

Induction of carcinoembryonic antigen and its crossreactive gene products in human colonic adenomas and carcinomas by transforming growth factor-beta.

The inducing effect of transforming growth factor-beta (TGF-B) on carcinoembryonic antigen (CEA) secretion and the cellular expression of CEA and CEA crossreactive glycoproteins (CEA-GLY) was examined from a panel of human colonic cell lines with different phenotypic classification. This panel included carcinomas with dissimilar differentiation characteristics and metastatic behavior, and premalignant adenomas derived from colonic polyps. A great degree of heterogeneity was observed in the endogenous levels of CEA secretion and the cellular expression of CEA and CEA-GLY species. The response profiles of the different cell lines to TGF-B treatment were also found to be heterogenous. However, TGF-B was able to induce CEA secretion and up-modulated the cellular expression of CEA and CEA-GLY from a majority of the cells tested. More importantly, TGF-B was able to exert these effects on carcinoma cells that secrete or express minimal or nondetectable amounts of these glycoproteins. These biologic modifying effects of TGF-B may have potential in augmenting the efficacy of CEA as a colon cancer marker, and in antibody-directed radioimaging and therapeutics. Further investigation in vivo in an experimental animal model system is warranted.

Adenoma↗
PubMed1990

Effects of combinations of interferon-beta ser and interferon-gamma on interferon-inducible proteins and on the cell cycle.

SKCO 1 human colon carcinoma cells have been shown to be synergistically inhibited in their growth by the combinations of alpha-interferon (IFN-alpha) or beta-interferon (IFN-beta ser) and gamma-interferon (IFN-gamma). To determine if a correlation could be established between this synergistic antiproliferative effect and a synergistic induction in IFN-inducible proteins, or a unique perturbation in the cell cycle, we studied the effects of IFN-beta ser and IFN-gamma, alone and in combination, on 2',5'-oligoadenylate (2-5A) synthetase, indoleamine-2,3-dioxygenase (IDO), a human analogue of the murine Mx protein (p78), and the phases of cell cycle. 2-5A synthetase was maximally induced after a 24-h exposure to both IFN-beta and IFN-gamma. A synergistic enhancement of 2-5A synthetase activity was observed only with low concentrations of each IFN (0.05 ng/ml). IDO activity was induced by IFN-gamma and the combination of IFN-beta ser and IFN-gamma, but not IFN-beta ser alone. The differences in IDO activity between IFN-gamma and the combination, however, were not statistically significant. The p78 protein was induced in a dose-dependent manner by IFN-alpha and IFN-beta ser. IFN-gamma enhanced the expression of p78 induction by IFN-alpha or IFN-beta ser, even at concentrations of IFN-gamma that did not induce the protein when administered as a single agent. The combination of IFN-alpha and IFN-beta ser, which results in an antagonistic antiproliferative effect, also resulted in an antagonistic induction of p78. No changes in the cell cycle were observed following exposure to IFN-beta ser, IFN-gamma, or the combination, and treatment with IFN-gamma did not inhibit the accumulation of cells in G2M caused by colchicine. Thus, the synergistic antiproliferative effect produced by IFN-beta ser and IFN-gamma in SKCO 1 cells could not be correlated with a synergistic enhancement in 2-5A synthetase or IDO activity, or with a perturbation in the cell cycle. In contrast, the combination of IFN-gamma and IFN-alpha or IFN-beta ser synergistically enhanced the expression of p78 protein in these cells.

2',5'-Oligoadenylate Synthetase↗
PubMed1989

Phase I trial of hepatic artery infusion of 5-iodo-2'-deoxyuridine and 5-fluorouracil in patients with advanced hepatic malignancy: biochemically based combination chemotherapy.

Eighteen patients with hepatic metastases primarily from colorectal carcinoma were treated on a phase I protocol employing hepatic artery infusion (HAI) of 5-fluorouracil (FUra) and 5-iodo-2'-deoxyuridine (IdUrd) via implantable infusion pump. Patients received a 14-day continuous HAI of 300 mg/day FUra. During days 8-14 of therapy, patients received IdUrd as a separate 3-h HAI daily x 7. Treatment cycles were repeated every 28 days. IdUrd was escalated from 0.1 to 2.86 mg/kg/day x 7. Myelosuppression and stomatitis were mild and not dose limiting. Hepatotoxicity was dose limiting and similar to that reported for 5-fluoro-2'deoxyuridine alone administered as a 14-day infusion every month. One patient developed a clinical picture consistent with sclerosing cholangitis and another had biopsy-proven cholestasis and triaditis. Catheter complications occurred in 7 of 18 patients. Plasma concentrations of FUra during the 7-day continuous HAI of FUra alone were consistently either undetectable or very low (less than or equal to 0.1 microM). At level 3 (1.0 mg/kg/day IdUrd) and beyond, measurable plasma concentrations of FUra, iodouracil, and IdUrd were found at the end of the daily 3-h infusion of IdUrd. The maximum tolerated dose of IdUrd as administered in this trial is 2.2 mg/kg/day x 7 and the recommended starting dose for further clinical investigation is 1.7 mg/kg/day x 7.

Animals↗
PubMed1989

Heterogeneity in the induction and expression of carcinoembryonic antigen-related antigens in human colon cancer cell lines.

Sodium butyrate induces morphological and biochemical changes consistent with a more differentiated phenotype in some colon cancer cell lines. These changes include increased expression of carcinoembryonic antigen (CEA) and other oncodevelopmental markers. We utilized domain-specific probes and polyclonal antibodies against CEA-related antigens to study sodium butyrate-induced expression of the CEA gene family in a villous adenoma-derived cell line, which is nontumorigenic in nude mice (VACO 235), and two colonic carcinoma cell lines known to respond to sodium butyrate exposure by phenotypic differentiation (HT-29 and LS 174T). The induction begins as quickly as 24 h after exposure and occurs primarily at a transcriptional level, although some translational control is also evident. No evidence was found for gene amplification, rearrangement, or methylation to account for the mechanism of this transcriptional control. [35S]Cysteine pulse-labeled cell lysate immunoblots and polyadenylated RNA blot hybridization suggest that increases in mRNA transcript and CEA-related glycoprotein levels are primarily due to increased synthesis rather than decreased degradation. A considerable amount of heterogeneity is seen in the biosynthesis of the CEA-related glycoproteins, with each cell line showing a distinct pattern of CEA-related antigen expression from a limited number of mRNA transcripts.

Adenocarcinoma↗