Growth in vitro of tumour cell × fibroblast hybrids in which malignancy is suppressed

1977 ◽  
Vol 25 (1) ◽  
pp. 73-86
Author(s):  
D.S. Straus ◽  
J. Jonasson ◽  
H. Harris
Keyword(s):  
Tumour Cell ◽  
Cloning Efficiency ◽  
Density Dependent ◽  
Inhibition Of Growth ◽  
Dependent Inhibition ◽  
Soft Agarose

We have studied the growth in vitro of a lymphoma × fibroblast hybrid and several melanoma × fibroblast hybrids in which malignancy is suppressed. The parental cells, the hybrids, and malignant segregants derived from the hybrids were analysed for serum requirement, cloning efficiency in soft agarose, density-dependent inhibition of growth, and secretion of plasminogen-activating enzyme. One malignant segregant from the lymphoma × fibroblast cross was found by a number of criteria to have a more highly ‘transformed’ phenotype than the hybrid from which it was derived. However, in the case of the melanoma × fibroblast crosses, none of the parameters examined could be correlated in a direct way with malignancy.

Release from Density-Dependent Inhibition of Growth in the Absence of Cell Locomotion

1974 ◽  
Vol 16 (1) ◽  
pp. 181-188
Author(s):  
MARGARET M. YARNELL ◽  
H. P. SCHNEBLI
Keyword(s):  
Insulin Treatment ◽  
Density Dependent ◽  
Mouse Fibroblasts ◽  
Cell Locomotion ◽  
Inhibition Of Growth ◽  
Dependent Inhibition ◽  
Cellular Locomotion

3T3 mouse fibroblasts are released from density-dependent inhibition of growth by treatment with insulin. The same insulin treatment stimulates cell locomotion several hours before any new mitoses become visible. Inhibition of cell locomotion by colcemid does not affect the overgrowth stimulation due to insulin. From this it is concluded that cellular locomotion is not a prerequisite for the release from density-dependent inhibition of growth.

Suppression of the transformed phenotype in somatic cell hybrids

1978 ◽  
Vol 33 (1) ◽  
pp. 171-190
Author(s):  
C.J. Marshall ◽  
H. Dave
Keyword(s):  
Somatic Cell ◽  
Tumour Cells ◽  
Transformed Cells ◽  
Somatic Cell Hybrids ◽  
Cell Hybrids ◽  
Recessive Mutations ◽  
Inhibition Of Growth ◽  
Dependent Inhibition ◽  
Hybrid Lines

Somatic cell hybrids between mouse mammary tumour cells (TA3B) and diploid rat embryo fibroblasts (REF) or between TA3B and Syrian hamster sarcoma cells (BI) were examined for the in vitro characteristics of transformed cells as soon as possible after cell fusion. Unlike the parental tumour cells as three of four TA3B X REF and five BI X TA3B independent hybrid lines had low colony-forming efficiencies in agar, exhibited density-dependent inhibition of growth and did not form colonies on confluent monolayers of 3T3 cells, demonstrating that the transformed phenotype was suppressed in these hybrids. In addition tests of some of the hybrid lines for tumour production in nude mice showed that this was also suppressed. Suppression was more stable in the TA3B X REF than in the BI X TA3B hybrids, variants of the BI X TA3B hybrids with the properties of transformed cells could be readily isolated by subculturing cells that had grown in agar. Tumour growth selected for hybrids with the characteristics of transformed cells, and derivatives of the hybrids selected to show the transformed phenotype readily produced tumours. These correlations suggest that the transformed phenotype and malignancy may be under the same control in these cells. The phenomenon of suppression may be explained by the hypothesis that neoplastic transformation results from recessive mutations in genes which control the normal phenotype. On this model the finding of suppression in hybrids between two different tumour lines is interpreted as complementation and indicates that the mutations are not the same in all cell lines.

scholarly journals Inhibition of DNA synthesis in SV3T3 cultures by isolated 3T3 plasma membranes.

1983 ◽  
Vol 97 (1) ◽  
pp. 276-279 ◽  
Author(s):  
S W Peterson ◽  
V Lerch
Keyword(s):  
Plasma Membrane ◽  
Dna Synthesis ◽  
Cell Cultures ◽  
Plasma Membranes ◽  
Inhibitory Effect ◽  
Density Dependent ◽  
Inhibition Of Growth ◽  
Dependent Inhibition ◽  
Membrane Components ◽  
Inhibition Of Dna Synthesis

3T3 plasma membranes were added to subconfluent cultures of SV3T3 cells in the presence of fusogens. If this protocol results in the introduction into the SV3T3 cell membrane of 3T3 plasma membrane components responsible for density-dependent inhibition of growth, then the SV3T3 cell cultures would be expected to show decreased rates of DNA synthesis as they approach confluence. Results of these experiments indicate that rates of DNA synthesis in SV3T3 cultures so treated were as much as 63% less than in untreated controls. This effect could not be attributed to the fusogens or to the 3T3 plasma membranes alone. This growth-inhibitory effect is specific for 3T3 membranes and is not observed when SV3T3 plasma membranes are fused with SV3T3 cell cultures. These data support the hypothesis that one aspect of the loss of density-dependent inhibition of growth in SV3T3 cells is a deletion or alteration in plasma membrane components and, further, that density-dependent inhibition of growth can be in part restored to SV3T3 cell cultures by fusing the cells with 3T3 plasma membranes.

scholarly journals Cell proliferation and cell density of mesenchyme in the maxillary process and adjacent regions during facial development in the chick embryo

Development ◽  
1978 ◽  
Vol 46 (1) ◽  
pp. 65-74
Author(s):  
Robert Minkoff ◽  
Amy J. Kuntz
Keyword(s):  
Cell Proliferation ◽  
Cell Density ◽  
Regulatory Mechanism ◽  
Satisfactory Explanation ◽  
Density Dependent ◽  
Dna Labeling ◽  
Inhibition Of Growth ◽  
Developmental Age ◽  
Dependent Inhibition ◽  
Facial Development

Cell proliferation, as measured by DNA labeling indices was analyzed during the early development of the maxillary process. Chick embryos were labeled with [3H]thymidine for .1 h and processed for autoradiography. The percentage of labeled mesenchymal cells was determined within delineated areas in the maxillary processes and in adjacent regions. Analysis of labeling indices in each of the areas at successive stages of development demonstrated a pattern of declining rates of cell proliferation with advancing developmental age. Cell proliferation in adjacent regions declined earlier and, in some instances, faster than it did in the maxillary process. Cell density was measured in the maxillary process and the roof of the stomodeum and was found to be higher in the maxillary process throughout the period studied. Cell density and cell proliferation data were analyzed with reference to the operation of ‘density-dependent inhibition’ of growth as a regulatory mechanism for the observed changes. ‘Density-dependent inhibition’ of growth was not a satisfactory explanation for the observed differences between the maxillary process and adjacent regions.

Density-Dependent Growth Inhibiting Interactions between 3T3 and SV40-3T3 Cells in Mixed Cultures

1979 ◽  
Vol 34 (3-4) ◽  
pp. 272-278 ◽  
Author(s):  
Jürgen van der Bosch ◽  
Heinz Maier
Keyword(s):  
High Serum ◽  
Dependent Manner ◽  
3T3 Cells ◽  
Density Dependent ◽  
Inhibition Of Growth ◽  
High Serum Concentration ◽  
Dependent Inhibition ◽  
Cell Population Growth ◽  
Dependent Growth ◽  
Growth Inhibiting

Abstract 3T3 cells are shown to reduce SV40-3T3 cell population growth in a density-dependent manner in co-cultures of 3T3 and SV40-3T3 cells. The development of this inhibitory activity roughly parallels the development of density-dependent inhibition of growth in homogeneous 3T3 control cultures. The extent of reduction of SV40-3T3 growth can be manipulated by pretreatment of 3T3 cells with a high serum concentration. SV40-3T3 growth rates are reduced by factors between 10 and 20 under optimum inhibitory conditions as compared to SV40-3T3 growth in control cultures.

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