[3H]thymidine labels less than half of the DNA-synthesizing cells in the mouse tumour, carcinoma NT.
We have studied carcinoma NT, a transplantable mouse adenocarcinoma of spontaneous origin. Cells labeled with [3H]thymidine ([3H]TdR) were restricted to a narrow zone around the periphery of this tumour and were also found in rings up to 50 micrometers wide, around isolated blood vessels in the central necrotic area. Labelling with [3H]deoxyuridine ([3H]UdR), another DNA synthesis precursor, produced a very different pattern. The labelled zone around the periphery was much wider than with [3H]TdR, and [3H]UdR labelled cells were found up to 110 micrometers from isolated vessels. [3H]iododeoxyuridine ([3H]IUdR) gave the same pattern of labelling as [3H]UdR. In the heavily labelled zone, within 1 mm of the tumour periphery, the labelling index (LI) was 51% after [3H]UdR or [3H]IUdR injection, and only 36% with [3H]TdR. The data show that at least half of the DNA-synthesizing cells in this tumour did not incorporate [3H]TdR. Previous workers reported cell loss factors for carcinoma NT of 60% calculated from [3H]TdR labelling data and 30% from the rate of loss of [125I]UdR. The present work suggests that calculations based on [125I]UdR data are more likely to be accurate for carcinoma NT than those using [3H]TdR data.
D000230:Adenocarcinoma / Q000378:metabolism*; D000818:Animals; D002455:Cell Division; D004273:DNA, Neoplasm / Q000096:biosynthesis; D003857:Deoxyuridine / Q000378:metabolism; D005260:Female; D007065:Idoxuridine / Q000378:metabolism; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D008938:Mitosis; D009374:Neoplasms, Experimental / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism*
D004273:DNA, Neoplasm; D007065:Idoxuridine; D013936:Thymidine; D003857:Deoxyuridine