Decreased gene expression for telomeric-repeat binding factors and TIN2 in malignant hematopoietic cells

Details of mechanisms regulating telomere length are poorly understood in human hematopoietic cells.

Gene expression for TRFs and TIN2 was studied in hematopoietic cell lines, blood or bone marrow cells from acute leukemia and in normal leukocyte fractions.

The telomeres were longest in normal leukocytes, shorter in patient samples and still shorter in malignant hematopoietic cell lines. TRF1 mRNA, TRF2 mRNA and TIN2 mRNA in three myeloblastic cell lines and six lymphoblastic cell lines were significantly less abundant than in the corresponding normal cell types. In patients with acute myeloid leukemia, expression of these gene was also less than in normal cells. In additional studies in culture, HL-60 cells with initially high telomerase activity and low expression of TRF mRNA and TIN2 mRNA differentiated into granulocytic and monocytic cells with low telomerase activity and high expression of these mRNAs.

In hematopoietic carcinogenesis, gene expression for suppressors of telomerase activity, such as TRF and TIN2, is decreased. These genes might hold promise for gene therapy against cancer.