LRRC4, a putative tumor suppressor gene, requires a functional leucine-rich repeat cassette domain to inhibit proliferation of glioma cells in vitro by modulating the extracellular signal-regulated kinase/protein kinase B/nuclear factor-kappaB pathway.
We have previously reported that the LRRC4 gene, which contains a conserved leucine-rich repeat (LRR) cassette and an immunoglobulin (Ig) IgC2 domain, is associated with glioma suppression both in vitro and in vivo. The present study provides evidence that the conspicuous absence of LRRC4 in high-grade gliomas directly contributes to the increasing tumor grade. The loss of LRRC4 in U251 cells is caused by the loss of homozygosity at chromosome 7q32-ter. It was also found that LRRC4 requires a functional LRR cassette domain to suppress U251 cell proliferation. In the LRR cassette domain, the third LRR motif of the core LRR is found to be indispensable for the function of LRRC4. The inhibitory effect of LRRC4 is accompanied by a decrease in the expression of pERK, pAkt, pNF-kappaBp65, signal transducer and activator of transcription protein-3 (STAT3), and mutant p53, and an increase in the expression of c-Jun NH2-terminal kinase (JNK)2 and p-c-Jun, suggesting that LRRC4 plays a major role in suppressing U251 cell proliferation by regulating the extracellular signal-regulated kinase (ERK)/Akt/NF-kappaBp65, STAT3, and JNK2/c-Jun pathways. In conclusion, LRRC4 may act as a novel candidate of tumor suppressor gene. Therefore, the loss of LRRC4 function may be an important event in the progression of gliomas.
Wu
Minghua
M
Cancer Research Institute, Central South University, Changsha, 410078 Hunan, People's Republic of China.
Huang
Chen
C
Gan
Kai
K
Huang
He
H
Chen
Qiong
Q
Ouyang
Jue
J
Tang
Yunlian
Y
Li
Xiaoling
X
Yang
Yixin
Y
Zhou
Houde
H
Zhou
Yanhong
Y
Zeng
Zhaoyang
Z
Xiao
Lan
L
Li
Dan
D
Tang
Ke
K
Shen
Shourong
S
Li
Guiyuan
G
D017209:Apoptosis; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D020869:Gene Expression Profiling; D016147:Genes, Tumor Suppressor; D005909:Glioblastoma / Q000473:pathology*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D000090263:Leucine-Rich Repeat Proteins; D050505:Mutant Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D051996:Transcription Factor RelA / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D000090263:Leucine-Rich Repeat Proteins; D050505:Mutant Proteins; D009419:Nerve Tissue Proteins; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D011506:Proteins; D051057:Proto-Oncogene Proteins c-akt; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; D013755:Tetradecanoylphorbol Acetate; D051996:Transcription Factor RelA; D016159:Tumor Suppressor Protein p53; C503331:LRRC4 protein, human