Activation of the ribosomal protein L13 gene in human gastrointestinal cancer.
Although ribosomal proteins are major components of ribosomes, recent data have shown them to have extraribosomal functions apart from ribosome and protein biosynthesis. In our earlier study, we showed that ribosomal protein L13 mRNA was up-regulated in response to DNA damage in hamster cells. We report here that L13 expression is up-regulated in human gastrointestinal cancers. We also examined the biological role of L13 on human cancer cells. Knocking down L13 expression using small interfering RNA (siRNA) resulted in drastic attenuation of cancer cell growth with significant G1 and G2/M arrest of the cell cycle. Moreover, L13 siRNA significantly enhanced the cellular sensitivity to certain DNA damaging agents and, concordantly, L13-overexpressing cells demonstrated greater chemoresistance compared to parent cells, suggesting an inverse correlation between L13 expression and chemosensitivity. By using semiquantitative RT-PCR, we analyzed expression of L13 in freshly resected cancer tissue of the stomach, colorectum and liver. Up-regulation of L13 mRNA expression was observed in 10 (28%) of 36 gastric, 19 (41%) of 46 colorectal and 5 (20%) of 25 liver cancer tissue samples compared to adjacent normal tissue samples. We also found that increased expression of the L13 gene correlated with clinical staging in gastric cancers. The results of this study suggest that L13 plays an essential role in the progression of some gastrointestinal malignancies.
Kobayashi
Toshihisa
T
First Department of Internal Medicine, Cancer Research Institute, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan.
Sasaki
Yasushi
Y
Oshima
Yuichiro
Y
Yamamoto
Hiroyuki
H
Mita
Hiroaki
H
Suzuki
Hiromu
H
Toyota
Minoru
M
Tokino
Takashi
T
Itoh
Fumio
F
Imai
Kohzoh
K
Shinomura
Yasuhisa
Y
D000818:Animals; D016466:CHO Cells; D002453:Cell Cycle / Q000235:genetics; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000235:genetics; D003106:Colon / Q000378:metabolism / Q000473:pathology; D006224:Cricetinae; D003412:Cricetulus; D004249:DNA Damage; D005753:Gastric Mucosa / Q000378:metabolism; D005770:Gastrointestinal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006801:Humans; D008099:Liver / Q000378:metabolism / Q000473:pathology; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012269:Ribosomal Proteins / Q000235:genetics* / Q000378:metabolism; D013270:Stomach / Q000473:pathology; D014162:Transfection; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000235:genetics
D009363:Neoplasm Proteins; D034741:RNA, Small Interfering; C085488:RPL13 protein, human; D012269:Ribosomal Proteins