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Chromatine immunoprecipitation (ChIP-seq) for RBPJ and SOX2 in Triple negative breast cancer MB157 cells and GSI-resistant MB157R cells upon induction of Notch1 or Sox2 signaling.

ABSTRACT: Cell plasticity of Triple negative breast cancer (TNBC) contributes to tumor heterogeneity and is one of the major reasons for the limited success of chemo- or combination therapies in the clinics. The molecular mechanisms of therapy-induced tumor cell plasticity and associated resistance to chemo or targeted therapies are largely unknown. Using a genome wide CRISPR-Cas9 screen we investigated the escape mechanisms of Notch driven TNBC, when treated with targeted therapy. We describe molecularly a reciprocal inhibitory feedback mechanism between Notch signaling and the pluripotency associated transcription factor SOX2, which shapes divergent cell states, EMT, cancer stem cell features and associates with therapeutic response and escape to targeted therapy. Moreover, we performed and assessed monotherapy and drug combination treatments in Notch-inhibitor sensitive and resistant TNBC xenotransplant and identified combination and second line treatment options which were able to induce tumor control and reduce metastatic burden.

ORGANISM(S): Homo sapiens

PROVIDER: GSE262007 | GEO | 2024/10/25

REPOSITORIES: GEO

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Project description:Triple-negative breast cancer (TNBC) is defined as pathologically negative for estrogen receptor α (ER-), progesterone receptor (PR-), and human epidermal growth factor receptor 2 (HER2) amplification. TNBCs are a heterogeneous group of clinically aggressive tumors with high risk of recurrence and metastasis. Current pharmacological treatment options remain largely limited to chemotherapy, recently supplemented by immunotherapy [37296893]. There is strong evidence supporting the involvement of Notch signaling in TNBC progression. Expression of Notch1 and its ligand Jagged1 correlate with poor prognosis. Notch inhibitors, including gamma secretase inhibitors (GSIs), are quite effective in preclinical models of TNBC. However, the success of GSIs in clinical trials has been limited by their intestinal toxicity and potential for adverse immunological effects, since Notch plays key roles in T-cell activation, including CD8 T-cells in tumors. Our overarching goal is to replace GSIs with agents that lack their systemic toxicity and ideally, do not affect tumor immunity. We identified sulindac sulfide (SS), the active metabolite of FDA-approved NSAID sulindac, as a potential candidate to replace GSIs. We confirmed that SS, a known gamma secretase modulator (GSM), inhibits Notch1 cleavage in TNBC cells. SS significantly inhibited mammosphere growth in all human and murine TNBC models tested. In a transplantable mouse TNBC tumor model (C0321), SS had remarkable single-agent anti-tumor activity and eliminated Notch1 protein expression in tumors. Importantly, the anti-tumor effects of SS were significantly enhanced when combined with α-PD1 immunotherapy in our TNBC organoids and in vivo. Our data support further investigation of SS for the treatment of TNBC, in conjunction with standard of care chemo- or -chemo-immunotherapy. Repurposing an FDA-approved, safe agent for the treatment of TNBC may be a cost-effective, rapidly deployable therapeutic option solution for a patient population in need of effective therapies.