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Inherent resistance of HeLa cell derivatives to paromomycin
Abstract:
The human tumor-derived cell line HeLa S3 and nuclear and mitochondrial gene mutants derived from it are resistant to the aminoglycoside antibiotic, paromomycin (PAR). Other carcinoma-derived cells, SV40-transformed cells, and four human diploid fibroblast cell lines are all sensitive to PAR. Sensitivity is dependent on cell density, and at cell numbers greater than 400/cm2 sensitive cells will proliferate in PAR. The resistance to PAR is inherited in a dominant manner in cell-to-cell fusion hybrids, but is not transferred in cytoplast-to-cell fusions. PAR resistance is therefore encoded by a nuclear gene(s). Resistance to PAR is not caused by changes in the response of mitochondrial or cytoplasmic protein synthesis to PAR in vitro. The uptake of PAR is similar in resistant and sensitive cells, and dimethyl sulfoxide does not render resistant cells more sensitive. Thus, HeLa cell PAR resistance is unlike previously reported ribosomal mutations and may derive from differences in the intracellular metabolism of PAR.
Insights
HeLa S3 cells exhibit resistance to the antibiotic paromomycin (PAR), unlike other cell types. This resistance is genetically determined by nuclear genes and not by mitochondrial factors or drug uptake.
Area of Science:
- Cell Biology
- Genetics
- Pharmacology
Background:
- The human tumor cell line HeLa S3 and its mutants display resistance to the aminoglycoside antibiotic paromomycin (PAR).
- In contrast, other carcinoma cells, SV40-transformed cells, and human diploid fibroblasts are sensitive to PAR.
- Cell density influences PAR sensitivity, with proliferation occurring in sensitive cells at densities above 400 cells/cm2.
Purpose of the Study:
- To investigate the genetic basis of paromomycin (PAR) resistance in HeLa S3 cells.
- To determine if PAR resistance is linked to mitochondrial function or drug uptake mechanisms.
- To differentiate the mechanism of PAR resistance in HeLa cells from previously identified ribosomal mutations.
Main Methods:
- Comparative analysis of PAR sensitivity across various human cell lines (HeLa S3, carcinoma, SV40-transformed, fibroblasts).
- Cell fusion experiments (cell-to-cell and cytoplast-to-cell) to assess inheritance patterns of PAR resistance.
- In vitro assays examining mitochondrial and cytoplasmic protein synthesis in response to PAR.
- Measurement of PAR uptake in both resistant and sensitive cell lines.
Main Results:
- PAR resistance in HeLa S3 cells is inherited in a dominant manner through nuclear genes, not extranuclear factors.
- Resistance is not attributable to altered mitochondrial or cytoplasmic protein synthesis inhibition by PAR.
- PAR uptake levels are comparable between resistant and sensitive cells, and DMSO does not restore sensitivity in resistant cells.
Conclusions:
- HeLa S3 cell paromomycin (PAR) resistance is conferred by nuclear gene(s).
- The resistance mechanism differs from known ribosomal mutations and is independent of drug uptake or protein synthesis alterations.
- PAR resistance in HeLa cells may stem from intracellular metabolic differences affecting the drug.