Research Impact: Custom Biocytogen mouse models used to identify critical mediator of inflammation-driven metastases
By John Charpentier, Ph.D.
September 7, 2022
While metastases are ultimately responsible for the large majority of cancer deaths, most oncology drugs in development target primary tumors, and few specifically prevent metastasis. Although surgical resection of solid tumors is an effective early treatment intervention, the resulting inflammation can promote metastasis by increasing adhesion of circulating tumor cells (CTCs) to endothelial cells on distant organs.
A new study featuring Biocytogen mice has identified a critical mediator of inflammation-driven metastasis which may be suitable for future therapeutic development. Fubing Li and colleagues at the Chinese Academy of Sciences detailed their findings last month in the journal Signal Transduction and Targeted Therapy.
A Ubiqiuitin Ligase Implicated in Metastasis
The group focused on the E3 ubiquitin ligase HECTD3, which had been previously shown to drive chemotherapeutic resistance in some models via its ubiquitination of MALT1, Caspase-8, and Caspase-9. To investigate a potential role in inflammation-driven metastasis, Li et al. orthotopically transplanted mouse breast tumor cells into both wild-type and Hectd3-deficient mice. Two months after surgical resection of the primary tumors, they discovered significantly fewer lung and heart metastases in Hectd3-deficient mice compared to controls. Additionally, tumor-bearing mice lacking HECTD3 lived significantly longer, supporting a role for the protein in promoting metastatic death.
To understand whether adhesion of CTCs to endothelial cells may be regulated by HECTD3 activity, Li and colleagues next performed genome-wide expression analysis in Hectd3-knock down human umbilical vein endothelial cells (HUVECs). The analysis identified dozens of target genes of the pleiotropic transcription factor NF-κB, including adhesion molecules and inflammatory mediators, that were downregulated in the knock-down cells relative to controls. Furthermore, global depletion of HECTD3 prevented inflammation-induced adhesion of tumor cells to endothelial cells both in vitro and in vivo.
Custom Generated Mouse Models Demonstrate HECTD3’s Role
To rigorously evaluate the endothelial-specific role of HECTD3 in promoting metastasis in vivo, the team turned to Biocytogen. We designed, generated, and validated two genetically engineered mouse models enabling conditional alterations in HECTD3 expression: one permitting murine endothelial cell-specific knock-out of Hectd3 and another permitting HECTD3 over-expression in the same cells. Using these models, Li and colleagues showed that CTC colonization was significantly abrogated in the former case and significantly enhanced in the latter.
Li’s group also characterized the mechanism by which HECTD3 activity drives metastasis: K63- and K-27-linked polyubiquitination at K296 of IKK-α (a.k.a. CHUK), a component of the IκB kinase complex regulating NF-κB. In the setting of post-surgical inflammation, this polyubiquitination activity prevents IKK-α degradation and results in its recruitment to adhesion molecule promoters, where it facilitates transcription.
Biocytogen’s custom gene-edited rodent and cell models are being used every day to accelerate the pace of preclinical biomedical research. You can learn more about our various platforms for custom model generation here.
Citation: Li F, Liang H, You H, et al. Targeting HECTD3-IKKα axis inhibits inflammation-related metastasis. Signal Transduct Target Ther. 2022;7(1):264. Published 2022 Aug 3. doi:10.1038/s41392-022-01057-0