LC3-mediated fibronectin mRNA translation induces fibrosarcoma growth by increasing connective tissue growth factor.
Previously, we related fibronectin (Fn1) mRNA translation to an interaction between an AU-rich element in the Fn1 3' UTR and light chain 3 (LC3) of microtubule-associated proteins 1A and 1B. Since human fibrosarcoma (HT1080) cells produce little fibronectin and LC3, we used these cells to investigate how LC3-mediated Fn1 mRNA translation might alter tumor growth. Transfection of HT1080 cells with LC3 enhanced fibronectin mRNA translation. Using polysome analysis and RNA-binding assays, we show that elevated levels of translation depend on an interaction between a triple arginine motif in LC3 and the AU-rich element in Fn1 mRNA. Wild-type but not mutant LC3 accelerated HT1080 cell growth in culture and when implanted in SCID mice. Comparison of WT LC3 with vector-transfected HT1080 cells revealed increased fibronectin-dependent proliferation, adhesion and invasion. Microarray analysis of genes differentially expressed in WT and vector-transfected control cells indicated enhanced expression of connective tissue growth factor (CTGF). Using siRNA, we show that enhanced expression of CTGF is fibronectin dependent and that LC3-mediated adhesion, invasion and proliferation are CTGF dependent. Expression profiling of soft tissue tumors revealed increased expression of both LC3 and CTGF in some locally invasive tumor types.
Ying
Lihua
L
Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305, USA.
Lau
Agatha
A
Alvira
Cristina M
CM
West
Robert
R
Cann
Gordon M
GM
Zhou
Bin
B
Kinnear
Caroline
C
Jan
Eric
E
Sarnow
Peter
P
Van de Rijn
Matt
M
Rabinovitch
Marlene
M
D000818:Animals; D002448:Cell Adhesion; D002460:Cell Line; D049109:Cell Proliferation; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism*; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism; D005354:Fibrosarcoma / Q000378:metabolism / Q000473:pathology; D020869:Gene Expression Profiling; D006801:Humans; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D020411:Oligonucleotide Array Sequence Analysis; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis; D051381:Rats
D055513:Connective Tissue Growth Factor; D005353:Fibronectins; D008869:Microtubule-Associated Proteins; C526109:Anxa3 protein, rat