Study of the expression of the gene encoding Ki-67 antigen in human pancreatic cancer using non-radioactive in situ hybridization and immunohistochemistry.
OBJECTIVE
To investigate, at transcriptional and translational level in situ, whether the gene expression of the Ki-67 protein in pancreatic carcinoma specimens is altered to get insight of the gene structure and function.


METHODS
Forty pancreatic cancer, 5 normal pancreatic and 4 chronic pancreatitis tissues were used in this experiment. A 435 bp cDNA fragment located in codon 2, exon 13 of Ki-67 antigen gene was amplified by the polymerase chain reaction (PCR). The DIG-labeled cRNA probes were transcribed using a commercial DIG RNA labeling kit. Localization of the Ki-67 protein and the specific mRNA was performed by combining immunohistochemistry (ICH) with DIG-labeled in situ hybridization (ISH).


RESULTS
Successful localization of the Ki-67 protein mRNA in pancreatic tissue sections, routinely formalin-fixed and paraffin-embedded, was first accomplished in this experiment. Analysis of the Ki-67 mRNA transcription in 17 pancreatic cancer specimens with Ki-67 ICH labeling index > 20% revealed stronger mRNA signals in poorly differentiated specimens with Ki-67 index > 50% than in well differentiated cases with the ICH labeling index of 20%-50%. A high expression of both the mRNA and the protein was observed in pancreatic adenocarcinomas with poor differentiation.


CONCLUSIONS
This is the first study in which the abnormal overexpression of the gene encoding Ki-67 protein was detected not only at the protein level, but also at the mRNA level in pancreatic tumours. The abnormal overexpression of the Ki-67 protein might be correlated with the central part, exon 13, of the gene.
Surgical Laboratory, Second Affiliated Hospital of Zhejiang Medical University, Hangzhou, China.
Y
Y
Wu
S
S
Peng
H
H
Sheng
D000230:Adenocarcinoma / Q000235:genetics*; D000951:Antigens, Neoplasm / Q000096:biosynthesis*; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D019394:Ki-67 Antigen / Q000096:biosynthesis*; D008297:Male; D010190:Pancreatic Neoplasms / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis
D000951:Antigens, Neoplasm; D019394:Ki-67 Antigen; D012333:RNA, Messenger