Tight junction Claudin proteins restrict invasive cancer cell behaviors in murine models of breast cancer
Embargo until
Date
2022-05-04
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Johns Hopkins University
Abstract
Breast cancer is the most common cancer diagnosed and second leading cause of death in women. Transcriptomic analyses have identified Claudin-low as a subtype of breast cancer, with low expression of tight junction genes Claudin 3, 4, 7, and Occludin as a key defining feature. While clinical and genomic studies have shown that Claudin-low is an aggressive subtype with poor prognosis, it remains unclear whether loss of these proteins is directly responsible for the aggressive cancer cell behaviors involved in metastatic disease. We hypothesized that Claudin proteins directly suppress invasive and metastatic cancer cell behaviors. We used a genetically engineered mouse model (GEMM) of basal breast cancer, C3(1)-Tag, to examine Claudin expression in primary tumors and in 3D organotypic assays of cancer cells derived from this mouse model. Our data revealed that Claudin 3 and Claudin 7 are heterogeneously expressed in C3(1)-TAg basal tumors, with expression lost in discrete regions within primary tumors. Using 3D ex vivo culture of tumor organoids, we also observed specific loss of Claudin expression in invading cells. To directly test our hypothesis, CRISPR gene-editing was used to deplete Claudin 3 and Claudin 7 in 3D organotypic assay. Upon individual knockout of Claudin 3 and Claudin 7 using CRISPR gene-editing, breast cancer organoids grown in 3D culture showed increased growth and collective invasion. Altogether, these findings indicate that Claudin 3 and Claudin 7 suppress collective invasion behaviors in primary breast cancer cells.
Description
Keywords
Claudins, tight junctions, claudin-low, collective invasion, metastasis, 3D organoids