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Telomere length and telomerase activity in canine mammary gland tumors

Mitsuhiro YazawaDepartment of Veterinary Internal Medicine, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan.

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Masaru OkudaLaboratory of Veterinary Internal Medicine, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan.

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Asuka SetoguchiDepartment of Veterinary Internal Medicine, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan.

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Shigehito IwabuchiCentral Research Laboratories, Nippon Zenyaku Kogyo, Fukushima 963-0196, Japan.

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Ryohei NishimuraDepartment of Veterinary Surgery, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan.

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Nobuo SasakiDepartment of Veterinary Surgery, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan.

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Kenichi MasudaDepartment of Veterinary Internal Medicine, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan.

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Koichi OhnoDepartment of Veterinary Internal Medicine, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan.

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Hajime TsujimotoDepartment of Veterinary Internal Medicine, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan.

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Abstract

Objective—To measure telomere length and telomerase activity in naturally occurring canine mammary gland tumors.

Sample Population—27 mammary gland tumor specimens obtained during resection or necropsy and 12 mammary gland tissue specimens obtained from healthy (control) dogs.

Procedure—Telomere length in tissue specimens was measured by use of restriction endonuclease digestion and Southern blot analysis. Telomerase activity was measured by use of a telomeric repeat amplification protocol assay.

Results—Telomere length in mammary gland tumors ranged from 11.0 to 21.6 kilobase pairs (kbp; mean ± SEM, 14.5 ± 0.5 kbp) but did not differ among tumor types. Telomeres in mammary gland tumors were slightly shorter than in normal tissue specimens, but telomere length could not be directly compared between groups, because mean age of dogs was significantly different between groups. Age was negatively correlated with telomere length in control dogs but was not significantly correlated with length in affected dogs. Telomerase activity was detected in 26 of 27 mammary gland tumors and in 4 of 12 normal tissue specimens. However, telomerase activity and telomere length were not correlated in tumor specimens.

Conclusion and Clinical Relevance—Telomere length is maintained in canine mammary gland tumors regardless of the age of the affected dog. Measurement of telomere length may be a useful tool for monitoring the in vivo effects of telomerase inhibitors in dogs with tumors. (Am J Vet Res 2001; 62:1539–1543)

Abstract

Objective—To measure telomere length and telomerase activity in naturally occurring canine mammary gland tumors.

Sample Population—27 mammary gland tumor specimens obtained during resection or necropsy and 12 mammary gland tissue specimens obtained from healthy (control) dogs.

Procedure—Telomere length in tissue specimens was measured by use of restriction endonuclease digestion and Southern blot analysis. Telomerase activity was measured by use of a telomeric repeat amplification protocol assay.

Results—Telomere length in mammary gland tumors ranged from 11.0 to 21.6 kilobase pairs (kbp; mean ± SEM, 14.5 ± 0.5 kbp) but did not differ among tumor types. Telomeres in mammary gland tumors were slightly shorter than in normal tissue specimens, but telomere length could not be directly compared between groups, because mean age of dogs was significantly different between groups. Age was negatively correlated with telomere length in control dogs but was not significantly correlated with length in affected dogs. Telomerase activity was detected in 26 of 27 mammary gland tumors and in 4 of 12 normal tissue specimens. However, telomerase activity and telomere length were not correlated in tumor specimens.

Conclusion and Clinical Relevance—Telomere length is maintained in canine mammary gland tumors regardless of the age of the affected dog. Measurement of telomere length may be a useful tool for monitoring the in vivo effects of telomerase inhibitors in dogs with tumors. (Am J Vet Res 2001; 62:1539–1543)