The PI3K/AKT pathway plays a pivotal role in hepatocellular carcinoma (HCC). Mutant PIK3CA, encoding the p110a catalytic subunit, stimulates the AKT pathway and promotes cell growth in various cancers. PIK3CA mutations have been researched in many cancer types and the mutation rate varies in HCC, which was reported in most studies with low frequency (<5%) except one report from Korea (35.6%). Therefore, we confirmed the frequency of PIK3CA mutation in Korean HCC patients.Methods
We sequenced the exons 1, 3, 4, 6, 7, 8, 9, 19 and 20 of PIK3CA in 268 HCC tumor tissues.Results
In this experiment, the mutations were not detected in exons 3, 6, 8 and 19 and detected 1 of 268 at unknown SNP (G278A) in exon 1 and at unknown SNP (C848G) in exon 4, 1 of 265 at unknown SNP (C1306A) and 2 of 265 at unknown SNP (C1373A) in exon 7, each of 262 at unknown SNP (T2970A) and SNP (G3026A) in exon 20. However, 1 of 266 was detected at unknown SNP (C1629T), 1 of 268 at G1635T (E545D) and 266 of 266 at A1634C (E545A) in exon 9. Additional experiments with normal tissue, cloning experiments and pyrosequencing assay revealed that the double peak at A1634C of exon 9 is not true mutation, but pseudogene, because exon 9 primers have high homology with the 22q11 partial region. There was no relationship between the clinical characteristic of HCC and the mutation of PIK3CA.Conclusions
In conclusion, our study suggests that the mutation frequency in PIK3CA gene of Korean HCC patients is low similar to other previous studies.