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Gene expression profiling in Indolocarbazole alkaloid Loonamycin A treated MDA-MB-231 cells

ABSTRACT: In triple negative breast cancer (TNBC), aberrant activation of Notch signaling plays an important role for the maintenance of cancer stem cell (CSC) stemness. Targeting CSCs via inhibition of Notch signaling can be a potential therapeutic option for this incurable disease. We previously used genome mining strategy to discover a new indolocarbazole alkaloid loonamycin A (Loo A). In this study, we demonstrate that Loo A has stronger cytotoxicity toward TNBC cells than its structural analog rebeccamycin. Apart from inhibition of TNBC cell proliferation and migration, Loo A reduced CD44high/CD24low/- sub-population, mammosphere formation, as well as the expression of stemness-associated genes. Co-administration of Loo A enhanced antitumor effects of paclitaxel by inducing apoptosis. RNA sequencing result showed that Loo A treatment caused the inhibition of Notch signaling, accompanied by the decreased expression of Notch1 and its targeted genes in TNBC cells. These results reveal a novel bioactivity of indolocarbazole-type alkaloids and provide promising Notch-inhibiting small molecular candidates for TNBC therapy.

ORGANISM(S): Homo sapiens

PROVIDER: GSE211143 | GEO | 2024/08/01

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.

Project description:Tumor-initiating cells with reprogramming plasticity and/or de-differentiation attributes have been thought to initiate primary tumor development as well as to regenerate secondary tumors in metastatic organs; however, the molecular mechanisms are not fully understood. We previously found that breast tumor-initiating cell marker, CD44, directs multicellular aggregation and cluster formation of circulating tumor cells (CTCs), which further enhance stemness and survival of such cells, enabling metastatic colonization to the lungs. To further elucidate the molecular network underlying CTC cluster formation, we performed global proteomic profiling and discovered that the tetraspanin protein CD81, which is normally enriched in exosomes (small extracellular vesicles), is a new driver of cancer initiation and metastasis as a facilitator and target of CD44. Loss of CD81 compromises tumorigenicity and mammosphere formation of triple negative breast cancer (TNBC) cells. Assisted by machine learning-based algorithms and mutagenesis approach, we found that CD81 interacts with CD44 on the cellular membrane through their extracellular regions. Notably, genetic knockout of CD44 or CD81 results in loss of both CD81 and CD44 in secreted exosomes, a state which abolishes exosome-induced self-renewal of recipient cells, such as mammosphere formation. In addition, RNA sequencing analysis showed that CD81 knockdown up-regulates expression of a cell differentiation marker, SEMA7a, whose down-regulation partially rescues mammosphere formation inhibition by CD81 depletion. Clinically, CD81 expression was observed in >80% of CTCs and specifically enriched and co-expressed along with CD44 in clustered CTCs of breast cancer patients. Mimicing the phenotypes of CD44 deficiency, loss of CD81 also inhibited tumor cell aggregation and lung metastasis of TNBC in both human and mouse tumor models, supporting the clinical significance of CD81 in association with patient outcomes. Our study highlights a new driving role of CD81 in cancer exosome-induced stemness, clustered CTCs, and metastasis initiation of TNBC, reported for the first time to our knowledge.

Project description:Background: Dendrobium officinale, an endangered Chinese herb, has extensive therapeutic effects and contains bioactive ingredients including a large number of polysaccharides and alkaloids, and minimal flavonoids. Firstly, this study attempts to obtain the protocorm-like bodies of this plant through tissue culture to produce the main secondary metabolites whose distribution in each organelle and protocorm like bodies is analyzed. Then, analysis of the correlation between comparative transcriptome sequence and the metabolite content in different organs enables the discovery of putative genes encoding enzymes involved in the biosynthesis of polysaccharides and alkaloids, and flavonoids. Results: The optimum condition for protocorm-like bodies (PLBs) induction and propagation of D. officinale is established. For protocorm induction, we use the seed as the explant, and the optimum medium formula for PLBs propagation is 1/2 MS + α-NAA 0.5 mg·L-1 +6-BA 1.0 mg·L-1 + 2, 4-D 1.5-2.0 mg·L-1 + potato juice 100 g·L-1. The distribution of polysaccharides, alkaloids and flavonoids in D. officinale organs was clarified. Stems, PLBs and leaves have the highest content of polysaccharides, alkaloids and flavonoids, respectively. PLBs replace organs to produce alkaloids in D. officinale, and naringenin was only produced in stem. Hot water extraction (HWE) method was found outperforming the ultrasound-assisted extraction (UAE) method for polysaccharides from D. officinale. A comparative transcriptome analysis of the protocorm-like bodies and leaves of D. officinale showed genes encoding enzymes involved in polysaccharides, alkaloids and flavonoids biosynthetic pathway were differentially expressed. Putative genes encoding enzymes involved in polysaccharides, alkaloids and flavonoids synthetic pathway were identified. Notably, genes encoding enzymes of strictosidine beta-glucosidase, geissoschizine synthase and vinorine synthase in alkaloids biosynthesis of D. officinale are first reported. Conclusions: Our works, especially the identification of candidate genes encoding enzymes involved in metabolites biosynthesis will help to explore and protect the endangered genetic resources and will also facilitate further analysis of the molecular mechanism of secondary metabolites’ biosynthesis in D. officinale.

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Gene expression profiling in Indolocarbazole alkaloid Loonamycin A treated MDA-MB-231 cells

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