Effects of normal human fibroblast mitochondrial DNA on segregation of HeLaTG mitochondrial DNA and on tumorigenicity of HeLaTG cells

J. I. Hayashi, H. Werbin, J. W. Shay

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Abstract

We isolated hybrids and cybrids using HeLaTG cells and human normal primary fibroblasts to examine the functional differences between the mitochondrial genomes of tumor and normal cells with respect to their possible involvement in the regulation of tumorigenicity. Hybrids contained mitochondrial DNA (mtDNA) predominantly from the fibroblast parent and their tumorigenicity was suppressed completely. Then, cytoplasmic transmission of primary fibroblast mtDNA to HeLaTG cells was carried out using toxin-antitoxin selection. Two hybrid clones containing a HeLaTG nucleus only and more than 60% of transmitted fibroblast mtDNA were isolated and injected into nude mice to test their tumorigenicity. They formed tumors when 2 x 106 cells were injected, whereas no tumors were formed after injection of 5 x 105 cells (a concentration at which HeLaTG subclones formed tumors). These cybrids were culivated in normal medium for two additional months and the content of fibroblast mtDNA increased gradually, resulting in HeLaTG mtDNA eventually being lost from both cybrid clones. We again examined their tumorigenicity and found that they recovered tumorigenicity completely. These results indicate that tumorigenicity of HeLaTG cells could not be suppressed by replacing their mitochondrial genomes with those of normal primary fibroblasts. Further, the partial suppression of tumorigenicity observed in the cybrid clones was temporary and may be due to cytoplasmic factors other than the mitochondrial genomes. Although we can find no difference between the mitochondrial genomes of normal and tumor cells regarding the regulation of tumorigenicity, the segregation pattern of the mtDNA in the cybrids was of interest: in the absence of any mitochondrial selection, HeLaTG mtDNA was lost while fibroblast mtDNA was retained, even though the nuclear component of these cybrids was the from HeLaTG cells. Thus, there should be some functional differences between the mitochondrial genomes of HeLaTG cells and primary fibroblasts that are responsible for the preferential segregation of HeLaTG mtDNA from the cybrids.

Original languageEnglish (US)
Pages (from-to)4001-4006
Number of pages6
JournalCancer Research
Volume46
Issue number8
StatePublished - 1986

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Mitochondrial DNA
Fibroblasts
Mitochondrial Genome
Clone Cells
Neoplasms
Carcinogenicity Tests
Antitoxins
Nude Mice
Injections

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

Effects of normal human fibroblast mitochondrial DNA on segregation of HeLaTG mitochondrial DNA and on tumorigenicity of HeLaTG cells. / Hayashi, J. I.; Werbin, H.; Shay, J. W.

In: Cancer Research, Vol. 46, No. 8, 1986, p. 4001-4006.

Research output: Contribution to journalArticle

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