Detection of Telomerase Activity in Lung Cancer Tissues

Cancer cells continue cell division and proliferation until they kill the host. Human germline cells have the capacity to undergo repeated cell divisions for millions of years, living on in descendants. However, most normal somatic cells can divide no more than several dozens of times. Recent research has shown that telomerase, a highly conserved reverse-transcriptase that adds G-rich nucleotide repeats onto the ends of chromosomal DNAs (i.e., telomeres), is the key that makes this difference (1 ,2) . Several thousands of clinical samples derived from human malignant neoplasms have been investigated for telomerase activity, and about 85% of them have been found to be positive for telomerase expression and activity (3) . In addition, almost all cancer cell lines established from human malignancies, all proliferating germline cells, most proliferating stem/progenitor cells (e.g., hematopoietic progenitor cells, intestinal crypt cells, skin epithelia, hair follicles, and endometrial cells), and activated lymphocytes exhibit telomerase activity. These findings would indicate that activation of telomerase is a prerequisite for human cells to prolong their life span of cell division. Therefore, detection of telomerase activity in clinical samples, which may be a marker of the presence of immortal cells, may be helpful for cancer diagnosis and inference of the malignant potential of tumors.