Diversity of keratin 19 gene expressed in lymph nodes of breast cancer patients

We have studied the expression of keratin 19 mRNA (K-19) in the axillary lymph nodes of breast cancer patients (n=100, serially from October 1997 to May 1998) in order to detect the micrometastasis by reverse transcriptase-polymerase chain reaction (RT-PCR). During the course of this study, (1) we encountered the 6 cases showing [n+, K-19(-)]. (2) To clear the discrepancy of the finding between histology and RT-PCR, some other primer pairs were used. In one case out of 6, K-19 was detected. (3) Further, the sequence of RT-PCR products showed diversity and could be roughly classified into 4 groups. Namely, group a (same sequence to the report of Genbank except for two bases), group b (almost same to group a except for one deletion and several point mutations), group c (approximate 50 bases were deleted from group a and with approximate 50 point mutations) and group d (almost same to group c except for several point mutations). Until now, we have not read the reports describing [n+, K-19(-)]. The discrepancy like these cases we experienced were partially cleared by using appropriate primer pairs.