MIDKINE EXPRESSION IN HUMAN BREAST CANCERS - EXPRESSION OF TRUNCATED FORM

The expression of midkine (MK), a growth/differentiation factor, was a ssessed in 34 surgically resected specimens of primary breast cancer o r mastopathy. Using reverse transcriptase-polymerase chain reaction (R T-PCR) analysis, all of the non-cancerous and cancerous tissues were f ound to express MK except for one breast cancer specimen. Northern blo t analysis revealed that MK mRNA was also expressed in the normal brea st tissues examined. Immunohistochemical analysis of the MK protein wa s performed on a limited number of the specimens, showing that some ca ncerous tissues were immunoreactive with anti-MK antibodies. Furthermo re, using RT-PCR analysis, expression of not only the wild-type but al so a truncated form of MK, which was recently found in various human t umor cell lines, was detected in 6 of 26 cancerous tissues but not in non-cancerous tissues.