Human kallikreins are a cluster of 15 serine protease genes located in the 
chromosomal band 19q13.4, a non-randomly rearranged region in many solid tumors, 
including pancreatic cancer. We utilized the SAGE and EST databases of the 
Cancer Genome Anatomy Project to perform in-silico analysis of kallikrein gene 
expression in normal and cancerous pancreatic and colon tissues and cell lines 
using virtual Northern blotting (VNB), digital differential display (DDD) and 
X-profiler. At least two kallikreins, KLK6 and KLK10, are significantly 
up-regulated in pancreatic cancer. We probed 2 normal and 6 pancreatic cancer 
SAGE libraries with gene-specific tags for each of these kallikreins. KLK6 was 
found to be expressed in 5/6 cancer libraries and showed the most marked 
(5-fold) increase in average expression levels in cancer vs. normal. These data 
were verified by screening the EST databases, where all mRNA clones isolated 
were from cancerous libraries, with no clones detected in normal pancreatic 
tissues or cell lines. X-profiler comparison of two pools of normal and 
cancerous pancreatic libraries further verified the significant increase of KLK6 
expression levels in pancreatic cancer. DDD data showed a 13-fold increase in 
KLK10 expression in pancreatic cancer. Three kallikrein genes, KLK6, 8 and 10 
are overexpressed in colon cancer compared to normal colon, while one 
kallikrein, KLK1, is down-regulated. While no expression of KLK6 was detected in 
normal colon, KLK6-specific tags were detectable in 2 cancer libraries. Similar 
results were obtained by EST screening; no KLK6 clones were detected in any of 
the 28 normal libraries examined, while 10 KLK6 EST clones were found in colon 
adenocarcinoma. KLK10 was not detectable in normal colon. Gene-specific tags 
were, however, detectable with high density in colon cancer and 7 EST clones 
were found to be expressed in colon Adenocarcinoma.