Gene and protein expression of RCAS1 in hepatocellular carcinoma.
BACKGROUND
RCAS1 (receptor-binding cancer antigen expressed on SiSo cells) is expressed on the tumor cell membrane and induces apoptosis in infiltrated lymphocytes. In the present study, the clinical importance of RCAS1 gene and protein expression were analyzed in surgically resected hepatocellular carcinomas (HCCs).


METHODS
RCAS1 gene and protein expression levels were evaluated and compared with clinical findings in 60 patients with HCC. Expression levels of RCAS1 messenger RNA (mRNA) from tumors was analyzed quantitatively by real-time reverse transcriptase polymerase chain reaction (RT-PCR). RCAS1 protein expression was analyzed by immunohistochemistry and the percentage of RCAS1-positive cancer cells was counted in each case.


RESULTS
RCAS1 messenger RNA levels significantly positively correlated with protein expression levels. RCAS1 protein expression was detected in 75% of cases and high RCAS1 immunoreactivity was detected in 19 tumors (31.7%). RCAS1 protein expression did not correlate with tumor differentiation, progression, nor disease-free survival. New tumors developed in the residual livers after resection of primary tumors in 39 patients. Treatment with transcatheter arterial embolization (TAE) from hepatic artery was performed in these patients. Survival periods after TAE treatment in these patients were analyzed. The mean survival period of 13 patients who had primary tumors with high RCAS1 protein expression (41.4 months) was significantly longer than that of 26 patients with low expression (23.5 months, p = 0.024). After TAE treatment, a low expression level of RCAS1 protein in primary tumors was recognized as a poor prognostic factor independently of tumor stage, by multivariate analysis, in patients who had developed new tumors in the residual livers.


CONCLUSIONS
RCAS1 protein expression in primary tumor may be a good marker for the effectiveness of TAE treatment in patients who develop new tumors in the residual livers.
Ikeguchi
Masahide
M
Division of Operating Room, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago 683-8504, Japan. masaike@grape.med.tottori-u.ac.jp
Hirooka
Yasuaki
Y
Kaibara
Nobuaki
N
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000096:biosynthesis* / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D004621:Embolization, Therapeutic; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics
D000951:Antigens, Neoplasm; C120762:EBAG9 protein, human; D012333:RNA, Messenger