Dataset Information

Lysyl Oxidase (LOX) Transcriptionally Regulates SNAI2 Expression and TIMP4 Secretion in Human Cancers.

ABSTRACT:

Purpose

Epithelial-to-mesenchymal transition (EMT) is important in cancer progression and metastasis. We and others have previously reported that lysyl oxidase (LOX) is overexpressed in aggressive cancers, is associated with increased mortality, and regulates EMT. However, the mechanism by which LOX mediates EMT is unknown. In this study, we investigated the effect of LOX on mediators of EMT.

Experimental design

We used chromatin immunoprecipitation and promoter luciferase assays to determine the target gene of LOX. To determine the effects of SNAI2 in vivo, we used our metastatic anaplastic thyroid cancer (ATC) mouse model. To investigate the effects of LOX and SNAI2 on MMPs and TIMPs, protein arrays were used. Primary tumors from patients with metastatic, breast and colon cancer, and tissue array for thyroid cancer were assessed for SNAI2 and TIMP4 expression by immunohistochemistry.

Results

We found that LOX knockdown decreases SNAI2 expression in cancer cell lines. Furthermore, knockdown of LOX reduced SNAI2 expression in a metastatic mouse model of thyroid cancer. We also demonstrated that LOX binds and transactivates the SNAI2 promoter. We found a direct correlation in thyroid and breast cancer samples between LOX and SNAI2 expression. To understand how LOX/SNAI2 axis mediates these effects, we performed a comprehensive analysis of MMPs/TIMPs. LOX and SNAI2 depletion reduced TIMP4 secretion. Analysis of SNAI2 and TIMP4 expression showed overexpression of both proteins in aggressive thyroid, colon, and breast tumors.

Conclusions

SUBMITTER: Boufraqech M

PROVIDER: S-EPMC8201910 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundIonizing radiation (IR) is a mainstay of cancer therapy, but irradiation can at times also lead to stress responses, which counteract IR-induced cytotoxicity. IR also triggers cellular secretion of vascular endothelial growth factor, transforming growth factor ? and matrix metalloproteinases, among others, to promote tumor progression. Lysyl oxidase is known to play an important role in hypoxia-dependent cancer cell dissemination and metastasis. Here, we investigated the effects of IR on the expression and secretion of lysyl oxidase (LOX) from tumor cells.MethodsLOX-secretion along with enzymatic activity was investigated in multiple tumor cell lines in response to irradiation. Transwell migration assays were performed to evaluate invasive capacity of naïve tumor cells in response to IR-induced LOX. In vivo studies for confirming IR-enhanced LOX were performed employing immunohistochemistry of tumor tissues and ex vivo analysis of murine blood serum derived from locally irradiated A549-derived tumor xenografts.ResultsLOX was secreted in a dose dependent way from several tumor cell lines in response to irradiation. IR did not increase LOX-transcription but induced LOX-secretion. LOX-secretion could not be prevented by the microtubule stabilizing agent patupilone. In contrast, hypoxia induced LOX-transcription, and interestingly, hypoxia-dependent LOX-secretion could be counteracted by patupilone. Conditioned media from irradiated tumor cells promoted invasiveness of naïve tumor cells, while conditioned media from irradiated, LOX- siRNA-silenced cells did not stimulate their invasive capacity. Locally applied irradiation to tumor xenografts also increased LOX-secretion in vivo and resulted in enhanced LOX-levels in the murine blood serum.ConclusionsThese results indicate a differential regulation of LOX-expression and secretion in response to IR and hypoxia, and suggest that LOX may contribute towards an IR-induced migratory phenotype in sublethally-irradiated tumor cells and tumor progression.