e15069 Background: Breast cancer has overtaken lung cancer as the most diagnosed cancer. Despite conventional treatment, metastases occur in 20-30% of patients, resulting in death. This study aims to screen of effective drugs by metastatic patient-derived organoid and the potential molecular mechanism. Methods: Breast Cancer patient-derived organoid (PDO) model was established from the patient who have multiple drug resistance, multiple visceral and contralateral breast metastases. The organoid morphologies was tested by hematoxylin-eosin (HE) staining and immunohistochemistry (IHC). Then, pharmacological activity assay of 2370 natural product monomer (from Selleck) was performed with organoids. we modified the structure of harmine(HM) and screened the best active drugs. Cell proliferation assay and wound healing assay were used to detect LN435a anticancer activity in vitro. Orthotopic, Metastatic Xenograft and Patient-Derived tumor Xenograft(PDX) model of Breast Cancer were used to detect LN435a anticancer activity in vivo. In order to explore the anti-cancer target of LN435a, we used RNA transcriptome and proteomics sequencing. To further validate anti-cancer targets,TGFβ receptor 1 (TGFβR1), we used real-time quantitative qPCR, western blot, lentiviral packing and biolayer interferometry assay. To investigate whether LN435a inhabition of EMT and stem cell markers, we performed flow cytometry, immunohistochemistry and fluorescence. Results: We observe that organoid morphologies typically matched the histopathology, hormone receptor status, and HER2 status of the original tumor. In the first anti-cancer drug screening, HM showes the best effect on PDO. Because HM contains β-carbine alkaloids as the structural units, we designe a series of active drugs based on this and did anticancer screening. We find LN435a as one of the lead compounds exerting anti-metastatic activity in the nanomolar range in PDO and breast cancer cells. Proteomic and biochemical studies identify TGFβR1 as the direct target of LN435a. And then it inhibits EMT and stem cell markers. In parallel, loss of TGFβR1 or pharmacological inhibition of TGFβR1 by LN435a reduces breast cancer extravasation into the lung in an experimental metastasis mouse model, which reveals an essential role of TGFβR1 in breast cancer progression. Conclusions: Altogether, LN435a is a novel inhibitor of promising anti-tumor effects on breast cancer that works by blocking TGFβ signaling pathways.
EXPRESSION OF TUMOR STEM CELL MARKERS IN REGIONAL AND DISTANТ BREAST CANCER METASTASES
