EXPRESSION OF 16-KDA PROTEOLIPID OF VACUOLAR-TYPE H-ATPASE IN HUMAN PANCREATIC-CANCER()

Recent studies have shown that bafilomycin A(1)-sensitive vacuolar-typ e H+-ATPase (V-ATPase) plays important roles in cell growth and differ entiation. However, there is no published study that has focused on th e expression of V-ATPase in human tumour tissues. This study was desig ned to examine the mRNA and protein levels for the 16 kilodalton (kDa) proteolipid of V-ATPase in human pancreatic carcinoma tissues. We fir st investigated the mRNA level for V-ATPase in six cases of invasive p ancreatic cancers and two normal pancreases, using reverse transcripti on-polymerase chain reaction technique, Then, we examined immunohistoc hemically the level of V-ATPase protein in 49 pancreatic cancers and t en benign cystic neoplasms of the pancreas, using antisera raised agai nst the 16 kDa proteolipid. There was a notable difference in the leve l of V-ATPase mRNA between normal and pancreatic carcinoma tissues, wi th no evident difference in the expression of the beta-actin gene. Imm unohistochemically, 42 out of 46 invasive ductal cancers (92%) display ed a mild to marked immunoreactivity for V-ATPase in the cytoplasm, wh ereas neither non-invasive ductal cancers nor benign cystic neoplasms expressed detectable immunoreactive proteins. These findings suggest t hat the overexpression of V-ATPase protein is characteristic of invasi ve pancreatic tumours. V-ATPase may play some crucial roles in tumour progression.