Telomere Length Measurement in Human Tissue Sections by Quantitative Fluorescence In Situ Hybridization (Q-FISH)

Telomeres in most somatic cells shorten with each cell division, and critically short telomeres lead to cellular dysfunction, cell cycle arrest, and senescence. Thus, telomere shortening is an important hallmark of human cellular senescence. Quantitative fluorescence in situ hybridization (Q-FISH) using formalin-fixed paraffin-embedded (FFPE) tissue sections allows the estimation of telomere lengths in individual cells in histological sections. In our Q-FISH method, fluorescently labelled peptide nucleic acid (PNA) probes are hybridized to telomeric and centromeric sequences in FFPE human tissue sections, and relative telomere lengths (telomere signal intensities relative to centromere signal intensities) are measured. This chapter describes our Q-FISH protocols for assessing relative telomere lengths in FFPE human tissue sections.