[In situ hybridization of tight junction molecule occludin mRNA in gastric cancer].
OBJECTIVE
To analyze the distribution and significance of occludin mRNA expression in human gastric cancer, as well as its relationship with gastric cancer pathology and multidrug resistance (MDR) in vivo.


METHODS
In situ hybridization (ISH) technique was used to evaluate the expression of occludin mRNA in 42 gastric carcinoma specimens obtained by surgery and 23 relatively normal gastric mucosa obtained by gastric endoscopy. All specimens had been stored in cryostatic section.


RESULTS
Occludin mRNA was found positive in the cytoplasm of gastric glandulous epithelia as blue particles with intensive stain in 14 of 42 gastric carcinomas (33.3%), 23 of 42 paracancerous gastric tissues (54.8%), 14 of 23 relatively normal gastric tissues (60.9%), 9 of 16 well differentiated carcinomas (56.3%), 4 of 14 moderately differentiated carcinomas (28.6%), 1 of 10 poorly differentiated carcinomas (10.0%) and none of 2 mucosal carcinomas. There were significant differences in occludin mRNA positive rate between relatively normal gastric tissue and gastric cancer as well as between paracancerous gastric tissue and gastric cancer. The expression of occludin mRNA in moderately and poorly differentiated groups was gradually reduced when compared with well differentiated group, which suggests that there be a significant correlation between tumor differentiation and the expression of occludin mRNA. Furthermore, the positive signals of occludin mRNA distributed extensively in the cytoplasm of SGC7901/VCR cell, being vincristine resistant, derived from parental gastric cell line SGC7901. The positive signals of SGC7901/VCR were stronger than those of SGC7901 cells.


CONCLUSIONS
Occludin mRNA, being mainly located in epithelial cells and its expression correlated with tumor differentiation, may be involved in the development of multi-drug resistance in gastric cancer.
Yin
Fang
F
Department of Gastroenterology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China.
Qiao
Taidong
T
Shi
Yongquan
Y
Xiao
Bing
B
Chen
Baojun
B
Miao
Jiyan
J
Fan
Daiming
D
D018432:Drug Resistance, Multiple / Q000502:physiology*; D019008:Drug Resistance, Neoplasm / Q000502:physiology; D006801:Humans; D017403:In Situ Hybridization; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D062793:Occludin; D012333:RNA, Messenger / Q000378:metabolism; D013274:Stomach Neoplasms / Q000378:metabolism*; D019108:Tight Junctions / Q000378:metabolism*
D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D012333:RNA, Messenger