Metabolic stress induces GD2(+) cancer stem cell-like phenotype in triple-negative breast cancer.

Metabolic stress resulting from nutrient deficiency is one of the hallmarks of a growing tumour. Here, we tested the hypothesis that metabolic stress induces breast cancer stem-like cell (BCSC) phenotype in triple-negative breast cancer (TNBC). Flow cytometry for GD2 expression, mass spectrometry and Ingenuity Pathway Analysis for metabolomics, bioinformatics, in vitro tumorigenesis and in vivo models were used. Serum/glucose deprivation not only increased stress markers but also enhanced GD2+ BCSC phenotype and function in TNBC cells. Global metabolomics profiling identified upregulation of glutathione biosynthesis in GD2high cells, suggesting a role of glutamine in the BCSC phenotype. Cueing from the upregulation of the glutamine transporters in primary breast tumours, inhibition of glutamine uptake using small-molecule inhibitor V9302 reduced GD2+ cells by 70-80% and BCSC characteristics in TNBC cells. Mechanistic studies revealed inhibition of the mTOR pathway and induction of ferroptosis by V9302 in TNBC cells. Finally, inhibition of glutamine uptake significantly reduced in vivo tumour growth in a TNBC patient-derived xenograft model using NSG (non-obese diabetic/severe combined immunodeficiency with a complete null allele of the IL-2 receptor common gamma chain) mice. Here, we show metabolic stress results in GD2+ BCSC phenotype in TNBC and glutamine contributes to GD2+ phenotype, and targeting the glutamine transporters could complement conventional chemotherapy in TNBC.

Jaggupilli A ，Ly S ，Nguyen K ，Anand V ，Yuan B ，El-Dana F ，Yan Y ，Arvanitis Z ，Piyarathna DWB ，Putluri N ，Piwnica-Worms H ，Manning HC ，Andreeff M ，Battula VL ... -  《-》

Anti-GD2 antibody dinutuximab inhibits triple-negative breast tumor growth by targeting GD2(+) breast cancer stem-like cells.

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype with no effective standard therapy. Breast cancer stem-like cells (BCSCs) in primary TNBCs are reported to be responsible for metastatic spread of the disease and resistance to chemotherapy, but no available therapeutic tools target BCSCs. We previously reported that the ganglioside GD2 is highly expressed on BCSCs and that inhibition of its expression hampers TNBC growth. We therefore hypothesized that the anti-GD2 antibody dinutuximab (ch14.18) targets GD2+ BCSCs and inhibits TNBC growth. To test our hypothesis, we first determined GD2 expression via immunohistochemistry in frozen primary tumor samples from patients with TNBC (n=89). Then, we examined the effects of dinutuximab on TNBC cell adhesion, migration, and mammosphere formation in vitro and on tumor growth in vivo using TNBC cell-line and patient-derived xenograft (PDX) models. We found that GD2 was expressed in around 60% of primary TNBC tumors at variable levels and was associated with worse overall survival of patients with TNBC (p=0.002). GD2 was found to be expressed in tumors and stroma, but normal ducts and lobules in adjacent tissues have shown low or no GD2 staining, indicating that GD2 is potentially a novel biomarker for tumor and its microenvironment. Treatment with dinutuximab significantly decreased adhesion and migration of MDA-MB-231 and SUM159 TNBC cells. Moreover, dinutuximab treatment inhibited mTOR signaling, which has been shown to be regulated by GD2 in BCSCs. Dinutuximab also reduced tumor growth in nude mice bearing TNBC cell-line xenografts. Finally, dinutuximab in combination with activated natural killer cells inhibited tumor growth in a TNBC PDX model and improved overall survival of tumor-bearing mice. Dinutuximab successfully eliminated GD2+ cells and reduced tumor growth in both in vivo models. Our data provide proof-of-concept for the criticality of GD2 in BCSCs and demonstrate the potential of dinutuximab as a novel therapeutic approach for TNBC.

Ly S ，Anand V ，El-Dana F ，Nguyen K ，Cai Y ，Cai S ，Piwnica-Worms H ，Tripathy D ，Sahin AA ，Andreeff M ，Battula VL ... -  《Journal for ImmunoTherapy of Cancer》

Ganglioside GD2: a novel therapeutic target in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is a heterogeneous disease characterized by lack of hormone receptor expression and is known for high rates of recurrence, distant metastases, and poor clinical outcomes. TNBC cells lack targetable receptors; hence, there is an urgent need for targetable markers for the disease. Breast cancer stem-like cells (BCSCs) are a fraction of cells in primary tumors that are associated with tumorigenesis, metastasis, and resistance to chemotherapy. Targeting BCSCs is thus an effective strategy for preventing cancer metastatic spread and sensitizing tumors to chemotherapy. The CD44hi CD24lo phenotype is a well-established phenotype for identification of BCSCs, but CD44 and CD24 are not targetable markers owing to their expression in normal tissues. The ganglioside GD2 has been shown to be upregulated in primary TNBC tumors compared with normal breast tissue and has been shown to identify BCSCs. In this review, we discuss GD2 as a BCSC- and tumor-specific marker in TNBC; epithelial-to-mesenchymal transition and the signaling pathways that are upstream and downstream of GD2 and the role of these pathways in tumorigenesis and metastasis in TNBC; direct and indirect approaches for targeting GD2; and ongoing clinical trials and treatments directed against GD2 as well as future directions for these strategies.

Shao C ，Anand V ，Andreeff M ，Battula VL ... -  《-》

Targeting breast cancer stem cells in triple-negative breast cancer using a combination of LBH589 and salinomycin.

Kai M ，Kanaya N ，Wu SV ，Mendez C ，Nguyen D ，Luu T ，Chen S ... -  《-》

IKK inhibition by BMS-345541 suppresses breast tumorigenesis and metastases by targeting GD2+ cancer stem cells.

Battula VL ，Nguyen K ，Sun J ，Pitner MK ，Yuan B ，Bartholomeusz C ，Hail N ，Andreeff M ... -  《Oncotarget》