Dataset Information

Endoxifen downregulates AKT phosphorylation through protein kinase C beta 1 inhibition in ERα+ breast cancer.

ABSTRACT: Endoxifen, a secondary tamoxifen metabolite, is a potent antiestrogen exhibiting estrogen receptor alpha (ERα) binding at nanomolar concentrations. Phase I/II clinical trials identified clinical activity of Z-endoxifen (ENDX), in endocrine-refractory metastatic breast cancer as well as ERα+ solid tumors, raising the possibility that ENDX may have a second, ERα-independent, mechanism of action. An unbiased mass spectrometry approach revealed that ENDX concentrations achieved clinically with direct ENDX administration (5 µM), but not low concentrations observed during tamoxifen treatment (<0.1 µM), profoundly altered the phosphoproteome of the aromatase expressing MCF7AC1 cells with limited impact on the total proteome. Computational analysis revealed protein kinase C beta (PKCβ) and protein kinase B alpha or AKT1 as potential kinases responsible for mediating ENDX effects on protein phosphorylation. ENDX more potently inhibited PKCβ1 kinase activity compared to other PKC isoforms, and ENDX binding to PKCβ1 was confirmed using Surface Plasma Resonance. Under conditions that activated PKC/AKT signaling, ENDX induced PKCβ1 degradation, attenuated PKCβ1-activated AKT^Ser473 phosphorylation, diminished AKT substrate phosphorylation, and induced apoptosis. ENDX's effects on AKT were phenocopied by siRNA-mediated PKCβ1 knockdown or treatment with the pan-AKT inhibitor, MK-2206, while overexpression of constitutively active AKT diminished ENDX-induced apoptosis. These findings, which identify PKCβ1 as an ENDX target, indicate that PKCβ1/ENDX interactions suppress AKT signaling and induce apoptosis in breast cancer.

SUBMITTER: Jayaraman S

PROVIDER: S-EPMC10730845 | biostudies-literature | 2023 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Endoxifen downregulates AKT phosphorylation through protein kinase C beta 1 inhibition in ERα+ breast cancer.

Jayaraman Swaathi S Wu Xinyan X Kalari Krishna R KR Tang Xiaojia X Kuffel Mary J MJ Bruinsma Elizabeth S ES Jalali Shahrzad S Peterson Kevin L KL Correia Cristina C Kudgus Rachel A RA Kaufmann Scott H SH Renuse Santosh S Ingle James N JN Reid Joel M JM Ames Matthew M MM Fields Alan P AP Schellenberg Matthew J MJ Hawse John R JR Pandey Akhilesh A Goetz Matthew P MP

NPJ breast cancer 20231219 1

Endoxifen, a secondary tamoxifen metabolite, is a potent antiestrogen exhibiting estrogen receptor alpha (ERα) binding at nanomolar concentrations. Phase I/II clinical trials identified clinical activity of Z-endoxifen (ENDX), in endocrine-refractory metastatic breast cancer as well as ERα+ solid tumors, raising the possibility that ENDX may have a second, ERα-independent, mechanism of action. An unbiased mass spectrometry approach revealed that ENDX concentrations achieved clinically with direc ...[more]

PMID: 38114522

Similar Datasets

Project description:Unlike breast cancer that is positive for estrogen receptor-α (ERα), there are no targeted therapies for triple-negative breast cancer (TNBC). ERα is silenced in TNBC through epigenetic changes including DNA methylation and histone acetylation. Restoring ERα expression in TNBC may sensitize patients to endocrine therapy. Expression of c-Src and ERα are inversely correlated in breast cancer suggesting that c-Src inhibition may lead to reexpression of ERα in TNBC. KX-01 is a peptide substrate-targeted Src/pretubulin inhibitor in clinical trials for solid tumors. KX-01 (1 mg/kg body weight-twice daily) inhibited growth of tamoxifen-resistant MDA-MB-231 and MDA-MB-157 TNBC xenografts in nude mice that was correlated with Src kinase inhibition. KX-01 also increased ERα mRNA and protein, as well as increased the ERα targets progesterone receptor (PR), pS2 (TFF1), cyclin D1 (CCND1), and c-myc (MYC) in MDA-MB-231 and MDA-MB-468, but not MDA-MB-157 xenografts. MDA-MB-231 and MDA-MB-468 tumors exhibited reduction in mesenchymal markers (vimentin, β-catenin) and increase in epithelial marker (E-cadherin) suggesting mesenchymal-to-epithelial transition (MET). KX-01 sensitized MDA-MB-231 and MDA-MB-468 tumors to tamoxifen growth inhibition and tamoxifen repression of the ERα targets pS2, cyclin D1, and c-myc. Chromatin immunoprecipitation (ChIP) of the ERα promoter in KX-01-treated tumors demonstrated enrichment of active transcription marks (acetyl-H3, acetyl-H3Lys9), dissociation of HDAC1, and recruitment of RNA polymerase II. Methylation-specific PCR and bisulfite sequencing demonstrated no alteration in ERα promoter methylation by KX-01. These data demonstrate that in addition to Src kinase inhibition, peptidomimetic KX-01 restores ERα expression in TNBC through changes in histone acetylation that sensitize tumors to tamoxifen.Implications: Src kinase/pretubulin inhibitor KX-01 restores functional ERα expression in ERα- breast tumors, a novel treatment strategy to treat triple-negative breast cancer. Mol Cancer Res; 15(11); 1491-502. ©2017 AACR.

Dataset Information

Endoxifen downregulates AKT phosphorylation through protein kinase C beta 1 inhibition in ERα+ breast cancer.

Publications

Endoxifen downregulates AKT phosphorylation through protein kinase C beta 1 inhibition in ERα+ breast cancer.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets