Reduced expression of the CXC chemokine hIRH/SDF-1α mRNA in hepatoma and digestive tract cancer

We isolated human intercrine reduced in hepatomas (hIRH) as a mRNA whose expression was reduced in differential displays from human hepatocellular carcinoma. hIRH is equivalent to the α-chemokine SDF-1α/PBSF. We have previously demonstrated on Northern blot analysis that although hIRH mRNA expression is common in human normal tissues, it is absent from pre-malignant colonic adenomas and from 27 human malignant cell lines. However, there are no reports on the mRNA status of hIRH in other human cancers. The present study was designed to investigate semi-quantitatively the expression of hIRH/SDF-1α mRNA in hepatocellular carcinoma and digestive tract cancers by reverse transcription-polymerase chain reaction (RT-PCR). The expression of hIRH/SDF-1α in the majority of cancer tissues analyzed was markedly reduced compared with that in adjacent non-cancer tissue. RT-PCR was more sensitive than Northern blots in the detection of hIRH mRNA. The average (mean±SE) tumor/normal (T/N) ratio determined by RT-PCR was 0.40±0.07 in 10 pairs of hepatoma, 0.38±0.09 in 14 pairs of colon cancers, 0.43±0.07 in IO pairs of esophageal cancers and 0.70±0.09 in 26 pairs of gastric cancers. As a control, the mean G3PDH T/N ratio was 1.16±0.06. The distribution of T/N ratios was significantly different between gastric cancer and the other cancers, but there was no correlation between hIRH/SDF-1α expression and clinico-pathological characteristics in gastric cancer. Our findings demonstrate that hIRH/SDF-1α expression is reduced in the majority of gastrointestinal tumors.