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.
Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305, USA.
Lihua
L
Ying
Agatha
A
Lau
Cristina M
CM
Alvira
Robert
R
West
Gordon M
GM
Cann
Bin
B
Zhou
Caroline
C
Kinnear
Eric
E
Jan
Peter
P
Sarnow
Matt
M
Van de Rijn
Marlene
M
Rabinovitch
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