Telomere length variation in normal and malignant human tissues.

Tissue and tumor specific length variation of telomere (TTAGGG)n repeats was studied in DNAs from various normal and malignant tissues. DNA was isolated from bone marrow and blood cells, malignant tissues, and established tumor cell lines. Nonisotopic Southern hybridization revealed a reduction of telomere repeat arrays in 14 of the 35 tumors analyzed. However, other cases (60%) showed no reduction, or even an increase, in telomeric length. Our finding of elongated telomere stretches in several tumors of different origin compared with normal tissue is in contrast to previous reports describing a general shortening of terminal repeat length in colorectal cancer and neuroblastoma. We tentatively conclude that there is no general tendency to telomere reduction in malignant tissues.