Identification of a novel lysyl oxidase-like 2 alternative splicing isoform, LOXL2 Delta e13, in esophageal squamous cell carcinoma
BIOCHEMISTRY AND CELL BIOLOGY-BIOCHIMIE ET BIOLOGIE CELLULAIRE
Authors: Lv, Guo-Qing; Zou, Hai-Ying; Liao, Lian-Di; Cao, Hui-Hui; Zeng, Fa-Min; Wu, Bing-Li; Xie, Jian-Jun; Fang, Wang-Kai; Xu, Li-Yan; Li, En-Min
Abstract
Lysyl oxidase-like 2 (LOXL2) participates in every stage of cancer progression and promotes invasion and metastasis. In this study, we identified a novel alternative splicing isoform of LOXL2, namely LOXL2 Delta e13, which lacked exon 13. Deletion of exon 13 caused an open reading frame shift and produced a truncated protein. LOXL2 Delta e13 was expressed ubiquitously in cell lines and tissues and was mainly localized to the cytoplasm. Although it showed impaired deamination enzymatic activity compared with full-length LOXL2, LOXL2 Delta e13 promoted the cell mobility and invasion of esophageal squamous cell carcinoma (ESCC) cells to greater degrees. In further research on the mechanisms, gene expression profiling and signaling pathway analysis revealed that LOXL2 Delta e13 induced the expression of MAPK8 without affecting the FAK, AKT, and ERK signaling pathways. RNAi-mediated knockdown of MAPK8 could block the cell migration promoted by LOXL2De13, but it had little effect on that of full-length LOXL2. Our data suggest that LOXL2 Delta e13 modulates the effects of cancer cell migration and invasion through a different mechanism from that of full-length LOXL2 and that it may play a very important role in tumor carcinogenesis and progression.
Increased Expression of the Matrix-Modifying Enzyme Lysyl Oxidase-Like 2 in Aggressive Hepatocellular Carcinoma with Poor Prognosis
GUT AND LIVER
Authors: Choi, Jiwoon; Chung, Taek; Rhee, Hyungjin; Kim, Young-Joo; Jeon, Youngsic; Yoo, Jeong Eun; Noh, Songmi; Han, Dai Hoon; Park, Young Nyun
Abstract
Background/Aims: Lysyl oxidase-like 2 (LOXL2), a collagen-modifying enzyme, has been implicated in cancer invasiveness and metastasis. Methods: We evaluated the expression of LOXL2 protein, in addition to carbonic anhydrase IX (CAIX), keratin 19, epithelial cell adhesion molecule, and interleukin 6, in 105 resected hepatocellular carcinomas (HCCs) by immunohistochemistry. Results: LOXL2 positivity was found in 14.3% (15/105) of HCCs, and it was significantly associated with high serum alpha-fetoprotein levels, poor differentiation, fibrous stroma, portal vein invasion, and advanced TNM stage (p<0.05 for all). Additionally, LOXL2 positivity was significantly associated with CAIX (p=0.005) and stromal interleukin 6 expression (p=0.001). Survival analysis of 99 HCC patients revealed LOXL2 positivity to be a poor prognostic factor; its prognostic impact appeared in progressed HCCs. Furthermore, LOXL2 positivity was shown to be an independent predictor of overall survival and disease-specific survival (p<0.05 for all). Interestingly, co-expression of LOXL2 and CAIX was also an independent predictor for overall survival, disease-specific survival, disease-free survival, and extrahepatic recurrence-free survival (p<0.05 for all). Conclusions: LOXL2 expression represents a subgroup of HCCs with more aggressive behavior and is suggested to be a poor prognostic marker in HCC patients.