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Telomeric DNA induces apoptosis and senescence of human breast carcinoma cells.

Yaar M, Eller MS, Panova I, Kubera J, Wee LH, Cowan KH, Gilchrest BA - Breast Cancer Res. (2007)

Bottom Line: We have identified an inducible cancer avoidance mechanism in cells that reduces mutation rate, reduces and delays carcinogenesis after carcinogen exposure, and induces apoptosis and/or senescence of already transformed cells by simultaneously activating multiple overlapping and redundant DNA damage response pathways.The human breast carcinoma cell line MCF-7, the adriamycin-resistant MCF-7 (Adr/MCF-7) cell line, as well as normal human mammary epithelial (NME) cells were treated with DNA oligonucleotides homologous to the telomere 3' overhang (T-oligos).Acting through ataxia telangiectasia mutated (ATM) and its downstream effectors, T-oligos induced apoptosis and senescence of MCF-7 cells but not NME cells, in which these signaling pathways were induced to a far lesser extent.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Dermatology, Boston University School of Medicine, Albany Street, Boston, MA 02118-2394, USA.

ABSTRACT

Introduction: Cancer is a leading cause of death in Americans. We have identified an inducible cancer avoidance mechanism in cells that reduces mutation rate, reduces and delays carcinogenesis after carcinogen exposure, and induces apoptosis and/or senescence of already transformed cells by simultaneously activating multiple overlapping and redundant DNA damage response pathways.

Methods: The human breast carcinoma cell line MCF-7, the adriamycin-resistant MCF-7 (Adr/MCF-7) cell line, as well as normal human mammary epithelial (NME) cells were treated with DNA oligonucleotides homologous to the telomere 3' overhang (T-oligos). SCID mice received intravenous injections of MCF-7 cells followed by intravenous administration of T-oligos.

Results: Acting through ataxia telangiectasia mutated (ATM) and its downstream effectors, T-oligos induced apoptosis and senescence of MCF-7 cells but not NME cells, in which these signaling pathways were induced to a far lesser extent. In MCF-7 cells, experimental telomere loop disruption caused identical responses, consistent with the hypothesis that T-oligos act by mimicking telomere overhang exposure. In vivo, T-oligos greatly prolonged survival of SCID mice following intravenous injection of human breast carcinoma cells.

Conclusion: By inducing DNA damage-like responses in MCF-7 cells, T-oligos provide insight into innate cancer avoidance mechanisms and may offer a novel approach to treatment of breast cancer and other malignancies.

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T-oligo decreases cell yield and induces S phase arrest in MCF-7 cells. Preconfluent cultures of (a) MCF-7 cells and (b) normal mammary epithelial (NME) cells were treated with 40 μM of GTTAGGGTTAG (T-oligo), CTAACCCTAAC (control oligo) or diluent alone and cell yields were determined at different intervals after oligonucleotide addition. Compared to controls, within 4 days T-oligo decreased cell yields 87 ± 9% (MCF-7; p < 0.04, n = 4) and 65.5 ± 0.01% (NME; p < 0.03, n = 2). (c) MCF-7 cells were treated as above and cells were collected for up to 96 hours for FACScan analysis after a single treatment at time 0. Averages and standard deviations were determined from duplicate samples. T-oligo increased the percent of cells in the S phase of the cycle as early as 48 hours after stimulation (p < 0.001, n = 2) and for at least 96 hours after stimulation (p < 0.04, n = 2).
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Figure 2: T-oligo decreases cell yield and induces S phase arrest in MCF-7 cells. Preconfluent cultures of (a) MCF-7 cells and (b) normal mammary epithelial (NME) cells were treated with 40 μM of GTTAGGGTTAG (T-oligo), CTAACCCTAAC (control oligo) or diluent alone and cell yields were determined at different intervals after oligonucleotide addition. Compared to controls, within 4 days T-oligo decreased cell yields 87 ± 9% (MCF-7; p < 0.04, n = 4) and 65.5 ± 0.01% (NME; p < 0.03, n = 2). (c) MCF-7 cells were treated as above and cells were collected for up to 96 hours for FACScan analysis after a single treatment at time 0. Averages and standard deviations were determined from duplicate samples. T-oligo increased the percent of cells in the S phase of the cycle as early as 48 hours after stimulation (p < 0.001, n = 2) and for at least 96 hours after stimulation (p < 0.04, n = 2).

Mentions: To determine the effect of T-oligo (11mer, 40 μM) on cell growth, we examined MCF-7 and NME cell yields up to 96 hours after a single supplementation of T-oligo (Figure 2). A decrease in MCF-7 yield was observed as early as 1 day after treatment. Diluent and control-oligo treated cells displayed exponential growth versus extremely little or no growth of T-oligo-treated cells. T-oligo decreased MCF-7 yields by 87 ± 9% within 4 days when the experiment was terminated (Figure 2a). Similarly, T-oligo inhibited NME proliferation, although the magnitude of the effect was smaller, with yields decreased by only 65.5 ± 0.01% after 4 days (Figure 2b). Modest but statistically less inhibition was observed in control oligo-treated cells.


Telomeric DNA induces apoptosis and senescence of human breast carcinoma cells.

Yaar M, Eller MS, Panova I, Kubera J, Wee LH, Cowan KH, Gilchrest BA - Breast Cancer Res. (2007)

T-oligo decreases cell yield and induces S phase arrest in MCF-7 cells. Preconfluent cultures of (a) MCF-7 cells and (b) normal mammary epithelial (NME) cells were treated with 40 μM of GTTAGGGTTAG (T-oligo), CTAACCCTAAC (control oligo) or diluent alone and cell yields were determined at different intervals after oligonucleotide addition. Compared to controls, within 4 days T-oligo decreased cell yields 87 ± 9% (MCF-7; p < 0.04, n = 4) and 65.5 ± 0.01% (NME; p < 0.03, n = 2). (c) MCF-7 cells were treated as above and cells were collected for up to 96 hours for FACScan analysis after a single treatment at time 0. Averages and standard deviations were determined from duplicate samples. T-oligo increased the percent of cells in the S phase of the cycle as early as 48 hours after stimulation (p < 0.001, n = 2) and for at least 96 hours after stimulation (p < 0.04, n = 2).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1851376&req=5

Figure 2: T-oligo decreases cell yield and induces S phase arrest in MCF-7 cells. Preconfluent cultures of (a) MCF-7 cells and (b) normal mammary epithelial (NME) cells were treated with 40 μM of GTTAGGGTTAG (T-oligo), CTAACCCTAAC (control oligo) or diluent alone and cell yields were determined at different intervals after oligonucleotide addition. Compared to controls, within 4 days T-oligo decreased cell yields 87 ± 9% (MCF-7; p < 0.04, n = 4) and 65.5 ± 0.01% (NME; p < 0.03, n = 2). (c) MCF-7 cells were treated as above and cells were collected for up to 96 hours for FACScan analysis after a single treatment at time 0. Averages and standard deviations were determined from duplicate samples. T-oligo increased the percent of cells in the S phase of the cycle as early as 48 hours after stimulation (p < 0.001, n = 2) and for at least 96 hours after stimulation (p < 0.04, n = 2).
Mentions: To determine the effect of T-oligo (11mer, 40 μM) on cell growth, we examined MCF-7 and NME cell yields up to 96 hours after a single supplementation of T-oligo (Figure 2). A decrease in MCF-7 yield was observed as early as 1 day after treatment. Diluent and control-oligo treated cells displayed exponential growth versus extremely little or no growth of T-oligo-treated cells. T-oligo decreased MCF-7 yields by 87 ± 9% within 4 days when the experiment was terminated (Figure 2a). Similarly, T-oligo inhibited NME proliferation, although the magnitude of the effect was smaller, with yields decreased by only 65.5 ± 0.01% after 4 days (Figure 2b). Modest but statistically less inhibition was observed in control oligo-treated cells.

Bottom Line: We have identified an inducible cancer avoidance mechanism in cells that reduces mutation rate, reduces and delays carcinogenesis after carcinogen exposure, and induces apoptosis and/or senescence of already transformed cells by simultaneously activating multiple overlapping and redundant DNA damage response pathways.The human breast carcinoma cell line MCF-7, the adriamycin-resistant MCF-7 (Adr/MCF-7) cell line, as well as normal human mammary epithelial (NME) cells were treated with DNA oligonucleotides homologous to the telomere 3' overhang (T-oligos).Acting through ataxia telangiectasia mutated (ATM) and its downstream effectors, T-oligos induced apoptosis and senescence of MCF-7 cells but not NME cells, in which these signaling pathways were induced to a far lesser extent.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Dermatology, Boston University School of Medicine, Albany Street, Boston, MA 02118-2394, USA.

ABSTRACT

Introduction: Cancer is a leading cause of death in Americans. We have identified an inducible cancer avoidance mechanism in cells that reduces mutation rate, reduces and delays carcinogenesis after carcinogen exposure, and induces apoptosis and/or senescence of already transformed cells by simultaneously activating multiple overlapping and redundant DNA damage response pathways.

Methods: The human breast carcinoma cell line MCF-7, the adriamycin-resistant MCF-7 (Adr/MCF-7) cell line, as well as normal human mammary epithelial (NME) cells were treated with DNA oligonucleotides homologous to the telomere 3' overhang (T-oligos). SCID mice received intravenous injections of MCF-7 cells followed by intravenous administration of T-oligos.

Results: Acting through ataxia telangiectasia mutated (ATM) and its downstream effectors, T-oligos induced apoptosis and senescence of MCF-7 cells but not NME cells, in which these signaling pathways were induced to a far lesser extent. In MCF-7 cells, experimental telomere loop disruption caused identical responses, consistent with the hypothesis that T-oligos act by mimicking telomere overhang exposure. In vivo, T-oligos greatly prolonged survival of SCID mice following intravenous injection of human breast carcinoma cells.

Conclusion: By inducing DNA damage-like responses in MCF-7 cells, T-oligos provide insight into innate cancer avoidance mechanisms and may offer a novel approach to treatment of breast cancer and other malignancies.

Show MeSH
Related in: MedlinePlus