Strikingly, we observed that the expression of podoplanin and ABCG2 within a single pre-neoplastic OE lesion significantly correlate with subsequently developing multiple and multifocal carcinomas, thus to some extent demonstrating the concept of field cancerization.
Furthermore, ABCG2 mRNA levels were significantly lower in adenomas and carcinomas compared to the level in unaffected tissue from the same individuals and compared to tissue from healthy individuals (P<0.0001 for all).
ABCG2 is one of at least three so-called multidrug resistant ABC transporters expressed in humans, and its activity is associated with decreased efficacy of anti-cancer agents in several carcinomas.
Cytoplasmatic accumulation of ABCG2 in poorly differentiated carcinomas might coincide with malfunctioning of PI3K-signaling pathways during tumor progression.