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Phenotypic variability in anchorage-independent growth by a human breast tumor cell line

, : Phenotypic variability in anchorage-independent growth by a human breast tumor cell line. Journal of the National Cancer Institute 72(4): 833-840

Possible mechanisms responsible for expression of anchorage independence were investigated with the use of the human breast carcinoma cell line Hs578T. This phenotype was not stable and most likely occurred via alterations in gene expression, causing secretion of growth factor (s). Colony-forming efficiency in methylcellulose was proportional to initial plating density at low passage number and increased with passage in culture. At high passages, there was less sensitivity to initial plating density, suggesting less dependence on surrounding cells for feeding effects. Clonal variants isolated in methylcellulose maintained a higher plating efficiency when kept in suspension, and removal of selective pressure resulted in the loss of the high level of expression upon subsequent challenge in suspension. In contrast to other systems, anchorage-dependent clones acquired the ability to grow in methylcellulose after only one passage in culture. This suggests that rapid variation at rates not typical of classical somatic mutation plays a role in expression of anchorage independence. Exposure to 5-azacytidine, which decreases methylation of DNA and may thereby activate gene transcription, increased the incidence of anchorage-independent growth 20 times; whereas treatment with 6-azacytidine had no effect. Unconcentrated medium conditioned by cells previously exposed to 5-azacytidine or by cells at high passage stimulated growth in suspension by as much as 10.9 times. The factor(s) present in this conditioned medium was stable to heat up to 63 degrees C for 30 minutes and was larger than 12,000-14,000 mol wt as determined by dialysis.


PMID: 6200640

Other references

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Nordestgaard, A., 1977: Trials with increasing rates of autumn and spring applied nitrogen for seed crops of perennial ryegrass, 1972-76. In trials at 4 locations in Denmark, perennial ryegrass grown for seed was undersown in barley and given 12 combinations of 0, 30 or 60 kg N/ha in autumn followed by 45, 90, 135 or 180 kg N/ha in spring. The 3 cv. used, Verna Pajbjerg (early), Dux...

Ayers J.W.T.; Washburnbrown A., 1984: Differential follicular and luteal responses to clomiphene therapy in women with amenorrhea and ovulatory dys function. Fertility & Sterility 41(2 SUPPL): 31S

Allegranza, A., 1968: Leukoencephalopathy with diffuse demyelination with perivascular accentuation. (New form of leukocystrophy?). Acta Neurologica 23(4): 639-648

Bystryak, S.M.; Mekler, V.M., 1992: Photochemical amplification for horseradish peroxidase-mediated immunosorbent assay. A new method for lowering the detection limit for a horseradish peroxidase (HRP) label in an enzyme-linked immunosorbent assay (ELISA) is proposed. The method is based on the use of a photochemical reaction of o-phenylenediamine (o-PD) autosensiti...

Binks, M.J.; Fernie-King, B.A.; Seilly, D.J.; Lachmann, P.J.; Sriprakash, K.S., 2005: Attribution of the various inhibitory actions of the streptococcal inhibitor of complement (SIC) to regions within the molecule. Some strains of Streptococcus pyogenes secrete a virulence factor called the streptococcal inhibitor of complement (SIC) function. SIC is a polyfunctional protein that interacts with a number of host proteins and peptides, especially with those th...

Wolframm, T., 2005: Change management: between motivation and frustration. Pflege Zeitschrift 58(6): 387-389

Agenjo, R., 1955: Anatomical differentiation and dispersal in Spain of A psi, A tridens and A cuspis. These spp. are easy to distinguish in their larval forms, but almost indistinguishable as imagos. Genitalia are described here, and lists of Spanish collection localities given.

Ciulla, M.; Paliotti, R.; Magrini, F., 1997: Ultrasonic reflectivity of the heart: a measure of fibrosis?. Advances in Experimental Medicine and Biology 432: 45-54

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