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Biomedical subjects

D L Dexter

Publications and source records attributed to D L Dexter.

At least 55 records · Page 3Linked to original sources
PubMed1983

"COLO 357," a human pancreatic adenosquamous carcinoma: growth in artificial capillary culture and in nude mice.

The human pancreatic cancer cell line COLO 357 has been xenografted s.c. in athymic Swiss mice. The xenografts grew well to form typical adenosquamous carcinomas. The cells were placed in a perfused artificial capillary system where they formed a solid tumor mass which survived for 7 weeks. In this system, the cells consumed glucose and released enzymes and carcinoembryonic antigen into the extracapillary space.

Adenocarcinoma↗
PubMed1983

Selection of metastatic variants from heterogeneous tumor cell lines using the chicken chorioallantoic membrane and nude mouse.

The chicken chorioallantoic membrane was used to select variant tumor cell subpopulations from the murine melanoma B16-BL6 and the rat glioma C6 cell lines. Tumor cells were deposited on the chicken chorioallantoic membrane of eggs 10 days postfertilization. Upon hatching, chickens were autopsied, and organs were removed, minced, and implanted s.c. in C57BL/6J mice (for melanoma) or nude mice (for glioma). A glioma growing s.c. from a chicken lung implant metastasized to the liver of the recipient nude mouse, and a melanoma growing s.c. from a chicken liver implant metastasized to the lung of its murine host. The s.c. melanoma contained distinct black and gray areas. Cell lines were established from the s.c. glioma (C6-V-1), from a metastasis of the C6-V-1 tumor (C6-V-2), and from the black and gray regions of the melanoma. Marked differences in lung colonization were seen 14 days after 1 X 10(5) parent BL6, Black, or Gray cultured cells were injected by tail vein into C57BL mice. In four separate experiments, fewer than 15 lung foci per mouse were found when BL6 cells were injected, whereas 100 to several hundred lung melanoma colonies per mouse were observed when Black or Gray cells were inoculated. Four of 18 nude mice bearing the s.c. C6-V-1 glioma developed liver metastases; no metastases have been observed in 15 nude mice bearing the s.c. parent C6 glioma. Significant differences in sensitivities to antineoplastic drugs were demonstrated between parent and variant glioma cell lines. The 33-fold increase in sensitivity to vincristine determined for C6-V-1 cells compared to parent C6 cells was particularly striking. Results suggest that the use of the chicken chorioallantoic membrane in situ, together with the nude mouse, might provide a method suitable for the selection and isolation of aggressive variants in heterogeneous human tumors.

Allantoin↗
PubMed1983

Thermal survival characteristics of cell subpopulations isolated from a heterogeneous human colon tumor.

Responses of a heterogeneous human colon adenocarcinoma model tumor system to in vitro hyperthermic treatment at various temperatures have been studied. This model tumor system consists of an original tumor line (DLD-1) obtained from surgical biopsy, and two derivative subpopulations termed clones A and D. These 3 tumor cell populations differ in many properties, including karyotype and DNA content, production of specific antigens, and sensitivities to other cytotoxic agents such as chemotherapeutic drugs and X-irradiation. In these experiments, exponentially growing tumor cells were exposed to hyperthermia (42.2, 42.5, 43.0, 44.0, or 45.0 degrees) for graded time periods. A single-hit, multitarget equation was used to express the dependence of survival on time at a given temperature, and values for extrapolation numbers, quasi-threshold time (min), and T0 (mean lethal time; min) were obtained for the initial regions of survival. At the lower temperatures of 42.2 and 42.5 degrees, biphasic survival curves were obtained for all three tumor lines and, as a consequence, a second mean lethal time (T0,f) was also determined for the final thermal-resistant portion of the survival curves. Using the T0 values as an index of relative resistance, values at 42.2 and 42.5 degrees indicated that, in this temperature region, the parent (DLD-1) line was the most sensitive, the clone A line showed intermediate sensitivity, and the clone D line was the most resistant. In the thermally resistant portion of the survival curve, T0 values indicated that the clone A subpopulation was the most sensitive, the DLD-1 line showed intermediate sensitivity, and the clone D tumor subpopulation remained the most resistant. At the higher temperatures of 43, 44, and 45 degrees, in which thermotolerance is not observed during heat treatment, values for T0 indicated the parent (DLD-1) tumor line was still the most sensitive tumor line, and the clone A and clone D lines showed approximately equal resistance. These data indicate that significant differences may exist among subpopulations of heterogeneous tumors in their survival responses to hyperthermia.

Adenocarcinoma↗
PubMed1983

Characterization of two metastatic subpopulations originating from a single human colon carcinoma.

Two separate cell lines originating from distinct metastatic deposits in a patient with a primary colonic carcinoma have been established both in vivo and in vitro. One metastasis, OM-1, was found in the omentum, and the other, HOT-3, was located on the ovary. These two metastases differ in several significant characteristics, including growth kinetics and the production of carcinoembryonic antigen by the cultured cells. OM-1 xenograft tumors contain about 8-fold more colonic mucin antigen than do HOT-3 heterografts. Similarities also exist. Both cell lines contain extra chromosomes in the A group, and both are missing chromosomes in Pair 14 of the D group and in Pair 18 of the E group. Xenograft tumors from these two metastases contain equivalent amounts of carcinoembryonic antigen and nonspecific cross-reacting antigen. These metastases developed through a process of progression and natural selection that occurred during the course of the patient's disease. Thus, the cell lines established from them provide material which may be used to study functional intraneoplastic diversity.

Antigens, Neoplasm↗
PubMed1982

Biochemical pharmacology and toxicology of 8-azaadenosine alone and in combination with 2'-deoxycoformycin (pentostatin).

The toxicology and metabolism of 8-azaadenosine (8-azaAdo) were examined both as a single agent and in combination with the adenosine deaminase inhibitor, 2'-deoxycoformycin (dCF). The LD10 (mice) for 8-azaAdo alone on a once daily for 5 days (q.d. x 5) schedule was 30 mg . kg-1 . day-1. When the animals were pretreated with 0.1 mg . kg-1 . day-1 of dCF, the LD10 dose was reduced to 10 mg . kg-1 . day-1 x 5. The major organ toxicity seen was hepatic. Bone marrow cellularity was only slightly altered at the LD10 dose. 8-AzaAdo nucleotides were detected in the livers of treated mice as determined by high performance liquid chromatography. Further, after 2 hr of incubation, isolated rat hepatocytes accumulated 8-azaATP to levels of 2.2 mumoles/g of cells with 8-azaAdo (1 mM) alone and to 4.3 mumoles/g of cells when 8-azaAdo was used in combination with dCF (1 microgram/ml). ATP levels decreased to below the limits of detection after 2 hr in cells treated with the combination. The replacement of cellular ATP by 8-azaATP may provide an explanation for the hepatotoxicity observed in the murine toxicology studies.

Adenosine↗
PubMed1982

Modification of the response of mouse skin to x-irradiation by a polar solvent, N,N-dimethylformamide.

The modification of the response of mouse skin to either single or split (24 hrs) graded doses of X rays by topically applied N,N-dimethylformamide (DMF) was investigated. DMF was applied daily for 5 days prior to irradiation. At a radiation dose level producing dry desquamation, DMF enhanced the X ray response by a factor of 1.3. Also, at the same level of response, the fraction of X ray dose repaired in 24 hours was 0.57, whereas for the DMF-treated and irradiated skin, this factor was 0.41, indicating a reduction of about 28% in subeffective damage repair. The times of maximal involvement of the skin reactions were not different in the X ray plus DMF treated mice versus mice receiving x-irradiation only. The data indicate that DMF is able to modify intrinsic radiation sensitivity of mouse skin epithelial cells, possibly through a reduction in the magnitude of the shoulder region of the survival curve.

Animals↗
PubMed1982

2'-Deoxycoformycin-induced hemolysis in the mouse.

2'-Deoxycoformycin (dCF), a tight-binding inhibitor of adenosine deaminase, has recently been entered into clinical trials. Toxicity has included lymphopenia, seizures, coma, conjunctivitis, renal failure, and hemolysis. Mice treated with dCF on a variety of schedules exhibited massive hemolysis. Hemolysis was brief, lasting about 20 hours, and did not recur upon readministration of the drug unless readministration was delayed for at least 6 days after initial exposure, which suggests that a sensitive subpopulation of cells was selectively destroyed. Splenectomy failed to protect the animals from dCF-induced hemolysis. Administration of adenosine or 2'-deoxyadenosine without dCF did not cause hemolysis, and use of these two agents with dCF did not potentiate the observed hemolysis. ATP and dATP levels were measured in erythrocytes, and changes in levels of these nucleotides did not correspond with the development of hemolysis.

Animals↗
PubMed1982

Differential responses to x-irradiation of subpopulations of two heterogeneous human carcinomas in vitro.

The responses of two heterogeneous human cancer cell lines and their derivative clones to graded single doses of X-rays were examined in vitro. One system consisted of the human colon carcinoma line DLD-1 and two subpopulations (clones A and D). The second system consisted of the human lung carcinoma line (LX1) and four subpopulations (LX1-1, LX1-2, LX1-3, and LX1-9). These subpopulations have previously been shown to be markedly heterogeneous in terms of such characteristics as karyotype, morphology, drug sensitivity, tumorigenicity, and expression of membrane glycoproteins (such as carcinoembryonic antigen and tumor colonic mucoprotein antigen). Exponentially growing cultures were irradiated with graded single doses of 100-kVp X-rays. Survival was assessed using colony formation as the end point, and responses from multiple experiments were fitted to the single-hit, multitarget equation of cell survival. Values for the mean lethal dose (D0, grays), quasithreshold dose (Dq, grays), and extrapolation number (n) were obtained. For the human colon adenocarcinoma system, these values for the three tumor lines were: DLD-1, 0.95, 2.34, and 11.7; clone A, 1.06, 2.23 and 8.20; and clone D, 1.08, 1.89, and 5.80. For the human lung carcinoma system, these values for the five sublines were: LX1, 1.14, 0.19, and 1.20; LX1-1, 0.96, 2.06, and 8.54; LX1-2, 0.98, 0.88, and 2.48; LX1-3, 0.68, 2.05, and 20.3; and LX1-9, 1.12, 0.00, and 1.00. These two human tumor systems therefore exhibit variability in their intrinsic sensitivity to X-irradiation. The data indicate that failure of some human carcinomas to respond to physical treatment modalities can be due to preexisting resistant subpopulations.

Adenocarcinoma↗
PubMed1982

Establishment and characterization of two human pancreatic cancer cell lines tumorigenic in athymic mice.

Two human pancreatic cancer lines, RWP-1 and RWP-2, have been established from 2 patients with primary pancreatic cancer metastatic to the liver. The patients' tumors, the xenografted tumors, and tumors obtained by inoculation of nude mice with cultured RWP-1 and RWP-2 cells are all moderately-well-differentiated ductal cell adenocarcinomas. Ultrastructural analysis supports the tissue histopathology findings. Xenografts of RWP-1 tumors double every 10 days, whereas the doubling time of RWP-2 xenografts is 22 days. Both tumors contain mucin. RWP-1 and RWP-2 cells have a doubling time in culture of 45 hr and form colonies in soft agar. RWP-1 cultures appear to be morphologically heterogeneous; two distinct epithelial cell types can be identified. RWP-1 and RWP-2 have modal chromosome numbers of 64 and 62, respectively. Appreciable levels of glucose-6-phosphate dehydrogenase and lactic dehydrogenase were found in both cell lines and xenografts. RWP-1 and RWP-2 cells produce appreciable amounts of carcinoembryonic antigen, 1090 and 414 ng/10(6) cells, respectively.

Adenocarcinoma↗
PubMed1982

Inhibition of the growth of human colon cancer xenografts by polar solvents.

The effects of N,N-dimethylformamide (DMF) and N-methyl-formamide (NMF) on the growth of two human colon cancer cell lines xenografted in nude mice were assessed. Toxicological studies with mice heterozygous for the nu/nu gene showed that with both compounds the limiting organ toxicity was hepatic. The 10% lethal doses for DMF and NMF given i.p. daily for 21 days were 2219 and 374 mg/kg, respectively. Nude mice (10/group) received s.c. transplants of HCT-15 or DLD- 2 human colon cancer cells. Mice were treated i.p. with the approximate 10% lethal doses of either DMF (daily for 21 days) or NMF (daily for 19 days) or with 0.9% NaCl solution when tumors became palpable. With the HCT-15 tumor, a growth inhibition of 65% was obtained using DMF compared to 0.9% NaCl solution-treated controls. Two independent experiments with DLD-2 demonstrated that DMF effected growth inhibitions of 45 and 67%. NMF treatment produced 48 and 75% growth inhibitions of HCT-15 and DLD-2 tumors, respectively. Weight loss of groups of treated mice in all experiments was between 2 and 14%, within the acceptable range for 10% lethal drug doses. Results indicate that some human cancer xenografts respond to the polar solvent DMF and to its metabolite NMF and that DMF may be acting at least in part by its metabolism to NMF. Furthermore, the data should alert clinical investigators to the possibility of hepatotoxicity when polar solvents are tested in Phase I clinical trials.

Animals↗
PubMed1981

Heterogeneity of cancer cells from a single human colon carcinoma.

The human colon carcinoma cell line DLD-1, established from tumor tissue obtained from a 45 year old white man with an adenocarcinoma of the sigmoid colon, was studied from the perspective of tumor heterogeneity. The karyotype and morphology of cells from an early passage DLD-1 culture, as well as the histologic features of both the original tumor and neoplasms produced by inoculation of athymic nude mice with DLD-1 cells, indicated that both the DLD-1 cell line and the original tumor were heterogeneous. Two clones were isolated from the DLD-1 line; they differed in their morphology, karyotype, and cloning efficiency in soft agar. Furthermore, when cells from each clone were injected into athymic mice, histologically distinct tumors were produced. Various analyses showed that the two cloned lines were representative of the two subpopulations predominantly responsible for the heterogeneity of the original neoplasm. In vitro drug screening results demonstrated that the two cloned lines have differential sensitivities to chemotherapeutic agents. The parent DLD-1 human colon carcinoma cell line and its two cloned subpopulations provide material for the study of various aspects and implications of human cancer cell heterogeneity.

Adenocarcinoma↗
PubMed1981

Induction by butyrate of differentiated properties in cloned murine rhabdomyosarcoma cells.

A cell line derived from the murine rhabdomyosarcoma BW10139 (Dexter, Cancer Res. 37: 3136, 1977) was subcloned and examined with respect to growth and myogenic characteristics in the presence and absence of 1 mM butyrate. Without butyrate, these cells behave as typical transformed cells: they grow rapidly and chaotically, do not form multinucleated muscle fibers and have little or no creatine kinase activity. In the presence of 1 mM sodium butyrate or butyric acid, growth slows, cells become arranged in whorl patterns, and creatine kinase activities increase to levels comparable to those found in normal chick myoblasts immediately prior to cell fusion. The increase in creatine kinase activity is detectable within 2 h exposure to butyrate, reaches a maximum by 24 h, and the elevated level can be maintained for at least six weeks. The induction is reversible upon sequential addition, deletion, and readdition of butyrate to the culture medium. Isoenzyme analyses demonstrated that only the BB form of creatine kinase is induced; MM creatine kinase was not detected. Although formation of multinucleated cells increases after exposure to butyrate, no typical myotubes form. The results suggest that this rhabdomyosarcoma cell line can, under appropriate conditions, re-express some properties characteristic of skeletal muscle, but not the complete muscle phenotype.

Animals↗