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G H Heppner

Publications and source records attributed to G H Heppner.

At least 55 records · Page 3Linked to original sources
PubMed1987

FACS analysis of tumor-associated macrophage replication: differences between metastatic and nonmetastatic murine mammary tumors.

The proliferation activity of adherent, tumor-associated macrophages (TAM) from three related murine mammary carcinoma lines was measured by fluorescence-activated cell sorter (FACS) analysis of the incorporation of 5'-Bromo-2'deoxyuridine (BrdU) in vivo during a 1 hr period prior to tumor removal. The tumor lines examined were line 67 which is nonmetastatic following either subcutaneous (SC) or intravenous (IV) injection, line 168 which colonizes the lung after IV injection but not SC, and line 66 which can colonize the lung from either site. The percentage of total cells identified morphologically as macrophages were similar for tumors from lines 66 and 67 (41% and 38%, respectively), as compared to line 168 tumors, in which, after digestion, 27% of cells were identified as macrophages (P less than or equal to 0.05). Adherent TAM from line 66 tumors had the greatest percentage of BrdU incorporating cells, with an average of 22%. This was statistically significant (P less than or equal to 0.01) from TAM from tumors of line 67, which were 13% positive. The percentage of adherent TAM from line 168 tumors (18% positive) was also significantly different from 67 TAM (P less than or equal to 0.01). These results demonstrate a possible correlation between the percentage of TAM undergoing replication and the ability of the host tumor to colonize the lung. There is no apparent relationship between the percentage of TAM in replication and the number of macrophages associated with a tumor.

Animals↗
PubMed1987

Analysis of tumour cell composition in tumours composed of paired mixtures of mammary tumour cell lines.

In order to quantitate the effects of tumour subpopulation interactions, we have devised a method to determine the subpopulation composition of tumours by using paired tumour cell lines able to grow in different selective media. Line 4T07 forms colonies in thioguanine but not in HAT and line 168 forms colonies in HAT but not in thioguanine. An independent technique of determining tumour cell content was used to validate this method: line 168 and 4T07 cells are distinguishable by flow cytometry after staining with propidium iodide for DNA content. Mixtures of cell suspensions prepared from each unmixed tumour, as well as from tumours arising from mixtures of these lines, were analysed by both the colony formation assay and by the DNA content assay. The colony formation assay yielded values in good agreement with the DNA content assay, but was considerably more sensitive in that it was able to quantitate minority subpopulations that constituted less than 10% of the tumour. Both methods revealed that in tumours arising from mixtures, the tumour cells were almost entirely line 4T07, even when the inoculum had contained a high proportion of 168 cells. Since line 168 cells are very tumorigenic per se, these results suggest that line 4T07 cells are capable of interfering with 168 proliferation in mixed tumours, either directly or through a host-mediated mechanism.

Aminopterin↗
PubMed1986

Inflammatory infiltrates of experimental mammary cancers.

The purpose of this review was to summarize observations on the type and function of inflammatory infiltrates of mouse mammary tumors and to speculate on the underlying mechanisms and the significance of infiltrates to mammary tumor biology. Although the major conclusion is that much more work is needed, certain themes seem to be emerging. The number of infiltrating cells can be very high but is unrelated to biological behavior of the tumors. What seems to be important is the relative contributions of inflammatory cell subsets. In the case of T-cell subsets and NK cells, the infiltrates from tumors of long-term cell lines so far seem uninformative. The general characteristics are similar to those of infiltrates from rapidly proliferating, normal mammary tissues. These characteristics do not correlate with diverse biological behavior or malignant potential. A more informative model appears to be one in which the development of tumors from preneoplastic tissue can be observed. Here our attention is currently focused on NK cells. By contrast, the correlation between activated TAM and metastatic behavior suggests that our transplantable MMT lines may be biologically relevant in the study of infiltrating macrophages. We are especially interested in the role of TAM in the generation of tumor cell variability. Overall, our data indicate that the host infiltrate is another manifestation of both inter- and intra-tumor heterogeneity and, as such, is not simply a response to, but, rather, a part of the tumor ecosystem. Unraveling the cellular and molecular mechanisms that govern the inflammatory cell component of tumors should provide insight into the types of cellular interactions that result in tumor development and progression.

Animals↗
PubMed1986

Macrophage-mediated induction of drug-resistant variants in a mouse mammary tumor cell line.

The ability of macrophages to induce drug-resistant variants was studied in an in vitro macrophage-tumor cell coculture system utilizing the hypoxanthine-guanine phosphoribosyl transferase locus as measured by resistance to 6-thioguanine. Tumor cells of mouse mammary tumor line 66 were sensitive to macrophage induction of thioguanine resistance as shown by an increase in the frequency of thioguanine-resistant variants which arose following macrophage coculture to levels at least 5- to 10-fold above the spontaneous frequency. Detection of increased numbers of variants depended upon the macrophage:tumor cell ratio, with 50:1 or greater being necessary. The activity of the macrophages was dependent upon their activation stage. The induction of drug-resistant variants could be inhibited by oxygen radical scavengers. The basis for the emergence of thioguanine-resistant cells appeared to be induction of new variants rather than selection of preexisting resistant cells from the parental population, since thioguanine-sensitive and -resistant cells were equally sensitive to macrophage-mediated toxicity. In six of the six macrophage-induced variants tested, resistance was associated with loss of hypoxanthine-guanine phosphoribosyl transferase activity. The reverse variation frequency at the hypoxanthine-guanine phosphoribosyl transferase locus in five macrophage-induced variants was low and similar to that of a stable ethyl methanesulfonate-induced, thioguanine-resistant line. Macrophages isolated directly from growing mammary tumors, as well as activated peritoneal macrophages, were capable of inducing thioguanine resistance in line 66 cells.

Animals↗
PubMed1986

Role of murine tumor models in cancer treatment research.

Two major factors have contributed to a widely held disenchantment with murine tumor models for drug screening in cancer research: (a) the higher costs of these models in comparison to studies performed with tumor cells in vitro; and (b) the perception that these models have failed to demonstrate satisfactory correlation of chemosensitivity with analogous human tumor types; i.e., murine tumors generally have proved to be sensitive to many more agents than are found to be active in the clinic. The perceived failure of the murine models is discussed with particular reference to the difference in criteria used for evaluating drug sensitivity in murine tumor models versus clinical trials, and we conclude that the perception about murine models is not tenable in light of present information. The very important role of murine tumor models in optimizing dosage and administration schedules and, most importantly, in the development of a new drug to its most useful potential in combination chemotherapy is discussed. The value of this in vivo methodology is stressed.

Animals↗
PubMed1985

FACS quantitation of leucine aminopeptidase and acid phosphatase on tumor-associated macrophages from metastatic and nonmetastatic mouse mammary tumors.

Macrophages were isolated by adherence from tumors produced by a number of murine mammary carcinoma lines and were examined by fluorescence-activated cell sorting for quantitation of leucine aminopeptidase and acid phosphatase. The tumors included three lines, 66, 67, and 168, which were originally derived from a single, spontaneously arising tumor in a BALB/cfC3H mouse and two other lines, D2A1 and D2F2, which were derived from a single tumor arising from the transplantable hyperplastic alveolar nodule line, D2. These five lines differ from one another in a number of characteristics, including the ability to metastasize spontaneously to the lung from subcutaneous implants and to form experimental metastases in lungs following intravenous injection. Line 67 is nonmetastatic under both circumstances, whereas lines 66, D2A1, and D2F2 are metastatic under the same conditions. Intermediate to these is line 168, which is nonmetastatic from the subcutaneous site but capable of colonizing the lung with an efficiency similar to 66 when injected IV. Tumor-associated macrophages (TAM) from lines 66, D2A1, and D2F2 contained the greatest amounts of leucine aminopeptidase (LAP) and those from line 67 the least, with TAM from 168 being intermediate. Conversely, the TAM from line 67 had the greatest amounts of acid phosphatase (APTase) and those from line 168 the least. In addition to differences among tumors in enzyme levels of the adherent TAM, the precentages of TAM that were adherent were also different among the tumors. Only 12% of TAM from line 67 were recovered in the adherent fraction as opposed to 35-38% of TAM from lines 66 and 168. These results confirm and extend our previous findings that TAM from metastatic tumors have increased levels of LAP compared to TAM from nonmetastatic tumors. They also demonstrate noncoordinate expression of LAP and APTase in TAM, and illustrate how a population of TAM can be homogeneous for one enzyme and heterogeneous for another. Furthermore, the difference in the percentage of macrophages that are adherent between metastatic and nonmetastatic tumors is another indication both of the heterogeneous nature of TAM and of the role of a tumor in determining the type of host infiltrate with which it is associated.

Acid Phosphatase↗
PubMed1985

A 3-dimensional tumor growth inhibition assay for testing monoclonal antibody cytotoxicity.

A 3-dimensional tumor growth inhibition assay [18] has been adapted to test the cytotoxic activity of a panel of monoclonal antibodies directed to various antigenic determinants on the surface of mouse mammary tumor cells. Target cells can be prepared from either cultured cells or from pieces of fresh tumor. Antibody and complement are added when cells are growing actively and cell growth can be measured, non destructively, over a 7-10-day period. Effective diffusion of antibody through collagen gel and binding to target cells embedded in the gel is demonstrated by indirect immunofluorescent staining. The specificity of monoclonal antibody AMT 101 cytotoxicity for mouse mammary tumor cells is the same in trypan blue exclusion assays of single-cell suspensions as in collagen gel assays, with complete killing seen in the collagen gel assay only. The collagen gel assay allows the testing of repeated treatments in vitro, as well as combined treatment with multiple antibodies. It also allows cell-cell interaction and preserves all cell components in the tumor. The collagen gel assay has potential as a method of predicting the outcome of monoclonal antibody treatment of solid tumors.

Animals↗
PubMed1985

Racial differences in breast cancer patients.

One thousand seventy-eight patients diagnosed with primary breast cancer were examined for racial differences in histopathologic and clinical parameters. There were no observed differences in tumor histopathologic type or tumor endocrine status between races. There were no differences with respect to time to breast tumor recurrence observed between black and white patients. However, differences were observed in factors that contributed to tumor stage at diagnosis and to tumor grade. Survival differences observed in univariant analysis of blacks vs. whites were explainable by the presence of more severe skin involvement, tumor grade, and tumor size at diagnosis in the black patients.

Black People↗
PubMed1985

T cell locomotion in the tumor microenvironment. I. A collagen-matrix assay.

Previous studies have shown that lymphocytic infiltrates of different mouse mammary tumors contain different proportions of the T cell subsets Lyt-1+ and Lyt-2+. These characteristic subset ratios may be established, at least in part, by differential locomotion of subsets in response to components of the tumor microenvironment, such as soluble chemotactic and chemokinetic factors, cell and stromal surfaces, oxygen tension, and pH. We describe a new in vitro assay for determining how such microenvironmental variables affect lymphocyte locomotion. Suspended lymph node cells, alone or mixed with other cell types, are sandwiched between two layers of type I collagen gel and bathed in culture medium. A halo of locomotory cells fans out around the flattened droplet. Locomotion requires energy and exogenous protein. After a 24-hr incubation at 37 degrees C, 10% CO2 in air, the cell density of the halo is analyzed optically and the subset ratios are characterized by immunofluorescence staining of the gel sandwich. Under standard culture conditions, the locomotory population is enriched 12% in Thy-1+ cells compared with the bulk population, and the ratio of Lyt-1+ to Lyt-2+ cells is significantly increased. Lymphocyte locomotion is inhibited by 1 microM PGE2, by decreased pH and oxygen tension, and by the presence of normal mammary cells or mammary adenocarcinoma cells. The Lyt-1+:2+ ratio in the locomotory population is not altered by PGE2 but is reduced by acidity and hypoxia. The ratio is also reduced by the presence of mammary cells and cells of one of the mammary adenocarcinoma cell lines tested (168) but not by two others (68H and 410). Our data support the hypothesis that the locomotion of T cell subsets is differentially responsive to the types of microenvironmental conditions that vary among tumors.

Animals↗
PubMed1985

Relationships of prostaglandin E and natural killer sensitivity to metastatic potential in murine mammary adenocarcinomas.

The levels of two prostaglandins (prostaglandins E and F) have been determined in a series of murine mammary lesions ranging from preneoplastic, hyperplastic alveolar nodules to highly metastatic adenocarcinomas. A highly positive correlation was seen between high levels of prostaglandin E and high tumorigenicity and metastatic potential. In addition, spontaneous metastasis of two highly metastatic tumors was partially inhibited by p.o. administration of indomethacin from the time of s.c. tumor transplantation until removal of the primary tumor at a limited size. Further, mammary tumor cells of differing metastatic potential were susceptible to polyinosinic-polycytidylic acid activated spleen lymphocytes in vitro. Cells of metastatic tumor lines (410.4 and 66) were more resistant to killing than were cells of two non-metastatic tumor lines (168 and 410). The sensitivity of all target cells was increased when endogenous prostaglandin synthesis was prevented by the addition of indomethacin (1 microM) but was not affected by the lipoxygenase inhibitor nordihydroguaiaretic acid.

Adenocarcinoma↗
PubMed1985

Correlation of frequency of induced mutation and metastatic potential in tumor cell lines from a single mouse mammary tumor.

Spontaneous mutation rates were determined in mouse mammary tumor subpopulation lines that differ in metastatic phenotype. Although there was almost a 9-fold difference in spontaneous rates to ouabain resistance among the three lines tested, the difference did not correlate with ability to metastasize. Similarly a 10-fold difference in spontaneous rates to 6-thioguanine resistance did not correlate with metastatic ability. In contrast, the frequency of ethyl methanesulfonate-induced mutations was associated with metastatic potential. Thus, ethyl methanesulfonate only induced significant numbers of 6-thioguanine resistant colonies in 66 and 410.4 cells, the only 2 of 5 lines tested that spontaneously metastasize at high frequency, and of ouabain resistant colonies in 66, 410.4, and 168 cells, the only lines tested that produce experimental lung metastases after i.v. injection. Differential sensitivity to induced mutation was not correlated with differences in plating efficiency, wild type sensitivity to ethyl methanesulfonate, 6-thioguanine, or ouabain toxicity, ploidy, cell shape, cell size, or ability to engage in metabolic cooperation.

Animals↗
PubMed1985

Factors affecting growth and drug sensitivity of mouse mammary tumor lines in collagen gel cultures.

A series of mouse mammary tumor subpopulation lines were compared for growth properties and sensitivity to chemotherapeutic drugs when grown as boluses in a collagen gel matrix versus in monolayer culture. Although the cell lines exhibited characteristic rates of bolus expansion in collagen, this growth was not paralleled by an exponential increase in cell number with time. Cell boluses contained a higher proportion of cells in G0-G1 phases of the cell cycle than did the same cell lines in monolayer cultures. Histological examination revealed areas of necrosis in boluses. Thus cells growing in collagen cultures resembled cells growing as solid tumors and cells from other three-dimensional culture systems. The growth of cell boluses in collagen gel cultures was reduced nonexponentially by melphalan, methotrexate, and 5-fluorouracil in contrast to the exponential decrease in growth measured in cloning assays. The lowest concentration to which cells first responded to drug was in general similar for collagen gel assays and for cloning assays. The rank order of sensitivity of different cell lines in the two assays was identical for methotrexate (four cell lines), similar for melphalan (four of five lines), but quite different for 5-fluorouracil. In contrast to cloning assays cell boluses continued to grow, albeit at a reduced rate, in the presence of high drug concentrations. This was not due to either diminished drug availability in collagen gel or drug penetration into the bolus.

Animals↗
PubMed1984

Assessing tumor drug sensitivity by a new in vitro assay which preserves tumor heterogeneity and subpopulation interactions.

We have designed an in vitro assay to assess the influence of tumor subpopulation interactions on drug response. The assay is based upon inhibition of growth of 1 mm3-pieces of tumor embedded in a collagen gel matrix. Tumor growth is quantitated by planimetry of each colony's image, formed with a split image tracing device attached to an inverted microscope. That expansion of the colonies in collagen gel represents growth through cell replication was demonstrated by releasing and counting cell nuclei. Outgrowths from pieces of tumors produced by a series of mouse mammary tumor subpopulation lines expanded in collagen gel at a rate characteristic of each cell line: the growth rate of tumor pieces was similar to that of the corresponding tumor line embedded as a cell bolus of cultured cells, indicating that growth of pieces of tumor is due to the tumor cells rather than to stromal components. When two cell lines were grown together in collagen cultures, interactions affecting growth rate were observed. Both tumor pieces and cell boluses from cultured cells of the relatively homogeneous cell lines displayed similar, characteristic sensitivities to adriamycin (ADR) in the collagen gel assay. Advantages of the collagen assay over cloning assays are (1) preservation of potential cellular interactions which may be important in assessing tumor drug sensitivity; (2) maximization of growth of all cell populations within the tumor, as compared to growth in agar; and (3) reflection of the zonal distribution of different subpopulations within tumors; and (4) simulation of the three-dimensional growth architecture found in vivo.

Animals↗
PubMed1984

Mutagenic activity of tumor-associated macrophages in Salmonella typhimurium strains TA98 and TA 100.

Suspensions of cells from a series of strain BALB/cfC3H mouse mammary tumors, and adherent and nonadherent cells from the tumors, were tested for their ability to increase the mutation rate of Salmonella typhimurium tester strains TA98 and TA100. Significant increases were seen with cells from three of four tumor lines tested on the TA98 strain and with one of four tested on the TA100 strain. The mutagenic activity was due primarily to cells in the adherent fractions which were greatly enriched for macrophages.

Animals↗
PubMed1983

Characterization of tumor-associated lymphocytes in a series of mouse mammary tumor lines with differing biological properties.

Tumor-associated lymphocytes were isolated by isokinetic gradient separation from five related mouse mammary tumor lines with different immunological and growth characteristics. Although considerable variation in recovery rates was seen from experiment to experiment, the five tumor types were found to have reproducible and characteristic patterns of T lymphocyte subpopulations, as detected by cytotoxicity assay using monoclonal antisera to Thy-1, Lyt-1, and Lyt-2 antigens. Tumors of line 168, which are weakly immunogenic at best, had the lowest numbers of recovered ALS+, Thy1+ lymphocytes (12% and 9%, respectively), in contrast to immunogenic lines (mean 38% and 26%, respectively). Line 68H tumors, which grow after prolonged latency periods and also produce tumor cell variants in vivo, were unique in that the numbers of recovered Lyt 1+ lymphocytes exceeded the number of Lyt 2+ lymphocytes, whereas these two T cell subpopulations were either equal or Lyt 2+ cells predominated in the other faster growing, non-variant-producing tumors. No differences in T lymphocyte distribution were associated with the presence or absence of metastatic behavior. These results indicate that distinctive lymphocyte infiltrates may be characteristic of tumors with distinct biological differences.

Animals↗