Elevated levels of RanBP7 mRNA in colorectal carcinoma are associated withincreased proliferation and are similar to the transcription pattern of the proto-oncogene c-myc

We have used suppression subtractive hybridisation, "in silico" cloning and reverse Northern dot blot analysis to identify significant up-regulation o f RanBP7 transcription in a human colorectal carcinoma. Quantitative RT-PCR analyses using the Taqman system demonstrated that RanBP7 mRNA levels were elevated in 47/75 colorectal tumours. There was no significant difference in 17 matched normal and tumour pairs and reduced levels in II. Since RanBP 7 specifies a key member of nuclear transport receptors responsible for the nuclear import of histone H1 and ribosomal proteins, we investigated wheth er this upregulation might be proliferation-associated. RanBP7 mRNA copy nu mbers were significantly correlated with those of proliferating cell nuclea r antigen in both normal and cancer tissue. Interestingly, the transcriptio n pattern of the proto-oncogene c-myc showed a similar correlation with PCN A mRNA. Our results highlight the need for the careful interpretation of qu antitative data that compare mRNA level in normal and cancer tissue. (C) 20 00 Academic Press.