Abstract 3373: Protein kinase D1 alleviate etoposide induced DNA damage through up regulation of alpha-catenin
Authors: Shukla Sanjeev , Serrano Samuel , Al-Toubat Mohammed , Osumi Teruko , Balaji K.C. 
Published: March 2024

Interaction between E-cadherin and β-catenin at cell-cell adherens junctions is pivotal in cell adhesion, and dysregulation of these genes is associated with disease progression in various solid tumors, notably in prostate cancer. α-catenin acts as a physical linker between the cadherin/β-catenin complex and actin cytoskeleton, through its mechanosensory properties has potential to modify interactions between cadherins and cytoskeleton and results in sensitivity of cells to DNA damage and toxicity. Membranous β-catenin interacts with the cellular cytoskeleton through threonine 120 (T120) phosphorylation and its association with α-catenin. We want to investigate the role of protein Kinase D1 (PrKD1) in DNA damage response, using various prostate cancer cell lines; PrKD1-silenced cells (LNCaP sh-PrKD1) and overexpression of PrKD1 (C4-2 PrKD1). PrKD1 silence and overexpress cells were treated with PrKD1 inhibitor and Etoposide to observe the effect of DNA damage repair altering various genes in prostate cancer cells. Silencing α-Catenin increased p-γH2AX (ser-139) expression in C4-2 PrKD1 cells. Conversely silenced PrKD1 (LNCaP sh-PrKD1) cells represented decreased α-Catenin expression, and increased p-γH2AX (ser-139). Overexpression of PrKD1 in prostate cancer cells increased α-catenin levels and conferred resistance to etoposide-induced DNA damage. Silencing PrKD1 compromised DNA damage protective effect. Furthermore, we elucidate the role of Protein kinase D1 (PrKD1), a unique serine-threonine kinase that phosphorylates β-catenin at T120, in this interaction. We treated C4-2 and C4-2 PrKD1 cells with PrKD1 inhibitor and immuno-precipitated β-Catenin complex represented decrease in β-Catenin (T-120) and α-Catenin than untreated C4-2 PrKD1 cells. We observed crosstalk between α-catenin and PrKD1 in DNA damage repair. In-silico analysis affirmed that the loss of T120 phosphorylation disrupts β- and α-catenin interaction. PrKD1 inhibitor decreased cell viability in dose response fashion, and also decrease the p-γH2AX (ser-139) in C4-2 PrKD1 cells than C4-2 cells. In vitro findings were corroborated in a mouse prostate cancer PDX xenograft model by inhibiting PrKD1 kinase activity, resulting in reduced β-catenin T120 phosphorylation and α-catenin levels. In vivo experiments with PrKD1 inhibitor represented tolerability in mice and its efficacy in modulating α-catenin and PrKD1 expression to inhibit tumor progression. Study for the first time provides a mechanistic basis of the protective role of PrKD1 against DNA damage.

Citation Format: Sanjeev Shukla, Samuel Serrano, Mohammed Al-Toubat, Teruko Osumi, K.C. Balaji. Protein kinase D1 alleviate etoposide induced DNA damage through up regulation of alpha-catenin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3373.