Cancer cells are a major source of
enzymes that modify
collagen to create a stiff, fibrotic
tumor stroma. High
collagen lysyl hydroxylase 2 (LH2) expression promotes
metastasis and is correlated with shorter survival in
lung adenocarcinoma (LUAD) and other
tumor types. LH2 hydroxylates
lysine (Lys) residues on
fibrillar collagen's amino- and carboxy-terminal telopeptides to create stable
collagen cross-links. Here, we show that electrostatic interactions between the LH domain active site and
collagen determine the unique telopeptidyl
lysyl hydroxylase (tLH) activity of LH2. However, CRISPR/Cas-9-mediated inactivation of tLH activity does not fully recapitulate the inhibitory effect of LH2 knock out on LUAD growth and
metastasis in mice, suggesting that LH2 drives LUAD progression, in part, through a tLH-independent mechanism.
Protein homology modeling and biochemical studies identify an LH2
isoform (LH2b) that has previously undetected
collagen galactosylhydroxylysyl glucosyltransferase (GGT) activity determined by a loop that enhances
UDP-glucose-binding in the GLT active site and is encoded by alternatively spliced exon 13 A. CRISPR/Cas-9-mediated deletion of exon 13 A sharply reduces the growth and
metastasis of LH2b-expressing LUADs in mice. These findings identify a previously unrecognized
collagen GGT activity that drives LUAD progression.