Abstract 3328: Association between LOX expression, LINE-1 DNA methylation and prognosis in esophageal cancer
Authors: Kalikawe Rebecca Tauzen , Baba Yoshifumi , Keisuke Miyake , Taisuke Yagi , Kitano Yuki , Hiroshi Sawayama , Yukiharu Hoyoshi , Maasaki Iwatsuki , Yuji Miyamoto , Naoya Yoshida , Takatsugu Ishimoto , Baba Hideo 
Published: August 2018

Background: Abnormal function of human body enzymes and epigenetic alterations such as DNA methylation lead to human carcinogenesis. Lysyl oxidase (LOX) is an extracellular matrix remodeling enzyme and its upregulation has been associated with poor prognosis in various cancers. LINE-1 methylation is considered as a surrogate marker of global DNA methylation and is attracting interest as a good predictor of cancer prognosis. Despite LOX involvement in tumor proliferation, migration and invasion in other types of tumors, the importance of LOX enzyme and its epigenetic regulation in pathogenesis of esophageal cancer has yet to be fully elucidated. Therefore, we constructed this study to examine the correlations between LOX expression, LINE-1 DNA methylation and the clinical pathological profile in patients with esophageal cancer.

Methods: mRNA expression array analysis was done using tissue biopsy and public array data. We then examined LOX expression in esophageal cancer using tissue biopsy by Real time PCR.LOX expression was evaluated in 284 surgically resected ESCC by immunohistochemistry, and the correlation was analyzed with LINE-1 methylation, obtained previously with pyrosequencing. In vitro we looked on LOXs role in tumor progression by growth and invasion assay using ESCC cell lines.

Results: Our microarray data reveled that LOX was the highly upregulated gene in hypo methylated tumors (fold change&gt;2X). In tissue biopsies LOX was significantly higher in tumor part compared to normal epithelium. In immunohistological study, LOX was identified in tumor cytoplasm. High LOX expression correlated with decrease in Overall survival, cancer-specific survival and disease-free survival. (P &lt;0.001**). Moreover, significant association with tumor size, invasion depth, tumor stage and lymph node metastases was also observed. In multivariate analysis LOX expression.

and tumor depth were an independent prognostic factor. Nevertheless, high LOX expression correlated to lower methylation levels (P=0.01). Invitro, we observed upstream of LOX expression by 5-AZA treatment but LOX knockdown had no influence in methylation levels. LOX knockdown suppressed growth in both TE6 and TE11 and reduced invasion and migration ability in TE 11 cell line.

Conclusions: Our findings show LOX is regulated epigenetically by genome wide hypomethylation and promote invasion and proliferation of ESCC. Hence, LOX can serve as a prognostic biomarker in ESCC patients and therapeutically targeting LOX could reverse progression of esophageal cancer.

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Citation Format: Rebecca Tauzen Kalikawe, Yoshifumi Baba, Miyake Keisuke, Yagi Taisuke, Yuki Kitano, Sawayama Hiroshi, Hoyoshi Yukiharu, Iwatsuki Maasaki, Miyamoto Yuji, Yoshida Naoya, Ishimoto Takatsugu, Hideo Baba. Association between LOX expression, LINE-1 DNA methylation and prognosis in esophageal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3328.