Project description:Triple negative breast cancer (TNBC) is an aggressive subtype that lack targeted clinical therapies. In addition, TNBC is heterogeneous and was recently further sub-classified into seven TNBC subtypes that displayed unique gene expression patterns. To develop therapeutic treatment regimens, we established seven patient-derived xenograft models from TNBC tumors. These xenograft models not only retained the histology and clinical markers of the corresponding patient tumors, but also bearing the same mutations and deletions identified in the patient tumors. Moreover, as part of evaluation of these models, we performed microarrays on the xenograft tumors to assess their TNBC subtypes. After obtaining IRB-approved informed written patient consent, breast cancer tissues were obtained fresh from Stanford Hospital and transplanted into the number 2 mammary fat pads of female NOD SCID mice (NOD.CB17-Prkdcscid/J, Jackson Laboratory West, Sacramento, CA, USA). Mice were maintained in pathogen-free animal housing. The established xenografts were subsequently passaged from mouse to mouse. Xenograft tumor tissues were frozen on dry ice for RNA isolation and microarray analysis.
Project description:Triple negative breast cancer (TNBC) is an aggressive subtype that lack targeted clinical therapies. In addition, TNBC is heterogeneous and was recently further sub-classified into seven TNBC subtypes that displayed unique gene expression patterns. To develop therapeutic treatment regimens, we established seven patient-derived xenograft models from TNBC tumors. These xenograft models not only retained the histology and clinical markers of the corresponding patient tumors, but also bearing the same mutations and deletions identified in the patient tumors. Moreover, as part of evaluation of these models, we performed microarrays on the xenograft tumors to assess their TNBC subtypes.
Project description:In vitro cell culture studies are common in cancer research field, and reliable biomimetic 3D models are needed to ensure physiological relevance. In this manuscript, we hypothesized that decellularized xenograft tumors can serve as an optimal 3D substrate to generate a top-down approach for in vitro tumor modeling. Methods: Multiple tumor cell lines were xenografted and the formed solid tumors were recovered for their decellularization by several techniques and further characterization by histology and proteomics techniques. Selected decellularized tumor xenograft samples were seeded with human triple negative breast cancer (TNBC)c ells and cell behavior was compared among them and with other control 2D and 3D cell culture methods. Results: A soft treatment using Freeze-EDTA-DNAse allows proper decellularization of xenografted tumor samples. Interestingly, proteomic data show that samples decellularized from TMBC xenograft models had different extracellular matrix (ECM) composition compared to the rest of xenograft tumors tested. The in vitro re-cellularization of decellularized ECM (dECM) yields tumor-type specific cell-behavior in TNBC context. Conclusions: Data indicate that dECM derived from xenograft tumors is a feasible substrate for re-seeding purposes, thereby promoting tumor-type specific cell behavior. These data serve as a proof-of-concept for further potential generation of patient-specific in vitro research models.
Project description:Plasticity delineates cancer subtypes with more or less favourable outcomes. In breast cancer, triple-negative is the subtype that lacks the expression of major differentiation markers (i.e. estrogen receptor [ER]), ant its high cellular plasticity results in higher aggressiveness and poor prognosis compared to other subtypes. Whether plasticity poses a vulnerability to cancer cells remains elusive. Here, we show that cancer cell plasticity can be exploited to differentiate triple-negative breast cancer. Using a high-throughput reporter drug screen with 9,501 compounds, we identify three polo-like kinase 1 (PLK1) inhibitors as major inducers of ER protein expression and downstream activity in triple-negative breast cancer cells via the transcription factor BATF. PLK1 inhibition upregulates a cell differentiation program characterized by increased DNA damage, mitotic arrest and ultimately cell death. Notably, cells surviving PLK1 inhibition have decreased tumorigenic potential, and targeting PLK1 in already established tumours reduces tumour growth both in cell line and patient-derived xenograft models. In addition, genes upregulated upon PLK1 inhibition are correlated with expression in normal breast tissue and confer better overall survival in breast cancer patients. Our results indicate that differentiation therapy based on PLK1 inhibition might be an alternative strategy to treat triple-negative breast cancer.
Project description:Breast cancer research is hampered by difficulties in obtaining and studying primary human breast tissue, and by the lack of in vivo preclinical models that reflect patient tumor biology accurately. To overcome these limitations, we propagated a cohort of human breast tumors grown in the epithelium-free mammary fat pad of SCID/Beige and NOD/SCID/IL2γ-receptor null (NSG) mice, under a series of transplant conditions. Both models yielded stably transplantable xenografts at comparably high rates (~23% and ~19%, respectively). Of the conditions tested, xenograft take rate was highest in the presence of a low-dose estradiol pellet. Overall, 32 stably transplantable xenograft lines were established, representing unique 25 patients. Most tumors yielding xenografts were “triple-negative” (ER-PR-HER2+) (n=19). However, we established lines from three ER-PR-HER2+ tumors, one ER+PR-HER2-, one ER+PR+HER2- and one “triple-positive” (ER+PR+HER2+) tumor. Serially passaged xenografts show biological consistency with the tumor of origin, are phenotypic stability across multiple transplant generations at the histological, transcriptomic, proteomic, and genomic levels, and show comparable treatment responses. Xenografts representing 12 patients, including two ER+ lines, showed metastasis to the mouse lung. These models thus serve as a renewable, quality-controlled tissue resource for preclinical studies investigating treatment response and metastasis. The study was designed to determine how stable patient-derived xenografts are across multiple transplant generations in mice, and to determine how closely xenografts established with pre-treatment samples cluster with xenografts established with post-treatment samples. Overall, pre-treatment and post-treatment samples derived from the same patient cluster together, and multiple transplant generations of xenografts derived from an individual patient cluster together.
Project description:Mass spectrometry profiling of orthotopically transplanted breast cancer patient-derived xenograft (PDX) tumors prior to chemotherapy treatment.
Project description:AXL is activated by its ligand GAS6 and is expressed in triple-negative breast cancer cells. We report that AXL is also detected in HER2+ breast cancer specimens where its expression correlates with poor patients’ survival. Using murine models of HER2+ breast cancer, AXL, but not Gas6, was found essential for metastasis. We determined that AXL is required for intravasation, extravasation and growth at the metastatic site. AXL is expressed in HER2+ cancers displaying EMT signatures and contributes to sustain EMT in murine tumors. Interfering with AXL in patient-derived xenograft impaired TGF-β-induced cell invasion. Lastly, pharmacological inhibition of AXL decreased the metastatic burden of mice developing HER2+ breast cancer. Our data identify AXL as a potential co-therapeutic target during the treatment of HER2+ breast cancers to limit metastasis.
Project description:AXL is activated by its ligand GAS6 and is expressed in triple-negative breast cancer cells. We report that AXL is also detected in HER2+ breast cancer specimens where its expression correlates with poor patients’ survival. Using murine models of HER2+ breast cancer, AXL, but not Gas6, was found essential for metastasis. We determined that AXL is required for intravasation, extravasation and growth at the metastatic site. AXL is expressed in HER2+ cancers displaying EMT signatures and contributes to sustain EMT in murine tumors. Interfering with AXL in patient-derived xenograft impaired TGF-β-induced cell invasion. Lastly, pharmacological inhibition of AXL decreased the metastatic burden of mice developing HER2+ breast cancer. Our data identify AXL as a potential co-therapeutic target during the treatment of HER2+ breast cancers to limit metastasis.
Project description:Cancer progression is associated with alterations of epigenetic regulators such as histone-lysine demethylases 4 (KDM4)2-5. During breast cancer therapy, classical treatments fail to address resistant cancer stem cell populations6-10. Here, we identified a novel KDM4 inhibitor (KDM4(i)) with unique preclinical characteristics. KDM4(i) is a highly potent pan KDM4 inhibitor that specifically blocks the demethylase activity of KDM4A, B, C, and D but not that of the other members of the KDM family. We validated the KDM4(i) anti-tumoral properties under conditions recapitulating patient tumors. Therefore, we established a method to isolate and grow triple-negative breast cancer stem cells (BCSCs) from individual patient tumors after neoadjuvant chemotherapy. Limiting dilution orthotopic xenografts of these BCSCs faithfully regenerate original patient tumor histology and gene expression. KDM4(i) blocks proliferation, sphere formation and xenograft tumor growth of BCSCs. Importantly, KDM4(i) abrogates expression of EGFR, a driver of therapy-resistant triple-negative breast tumor cells11, via inhibition of the KDM4A demethylase activity. Taken together, we present a unique BCSC culture system as a basis for therapeutic compound identification and demonstrate that KDM4 inhibition is a new therapeutic strategy for the treatment of triple-negative breast cancer.