Acetyl-CoA carboxylase 1 controls a lipid droplet-peroxisome axis and is a vulnerability of endocrine-resistant ER+ breast cancer.

Targeting aromatase deprives ER+ breast cancers of estrogens and is an effective therapeutic approach for these tumors. However, drug resistance is an unmet clinical need. Lipidomic analysis of long-term estrogen-deprived (LTED) ER+ breast cancer cells, a model of aromatase inhibitor resistance, revealed enhanced intracellular lipid storage. Functional metabolic analysis showed that lipid droplets together with peroxisomes, which we showed to be enriched and active in the LTED cells, controlled redox homeostasis and conferred metabolic adaptability to the resistant tumors. This reprogramming was controlled by acetyl-CoA-carboxylase-1 (ACC1), whose targeting selectively impaired LTED survival. However, the addition of branched- and very long-chain fatty acids reverted ACC1 inhibition, a process that was mediated by peroxisome function and redox homeostasis. The therapeutic relevance of these findings was validated in aromatase inhibitor-treated patient-derived samples. Last, targeting ACC1 reduced tumor growth of resistant patient-derived xenografts, thus identifying a targetable hub to combat the acquisition of estrogen independence in ER+ breast cancers.

Blockade of IL-10 Signaling Ensures Mifamurtide Efficacy in Metastatic Osteosarcoma.

Osteosarcoma (OS) is the most common primary malignancy of the bone, highly aggressive and metastasizing, and it mainly affects children and adolescents. The current standard of care for OS is a combination of surgery and chemotherapy. However, these treatment options are not always successful, especially in cases of metastatic or recurrent osteosarcomas. For this reason, research into new therapeutic strategies is currently underway, and immunotherapies have received considerable attention. Mifamurtide stands out among the most studied immunostimulant drugs; nevertheless, there are very conflicting opinions on its therapeutic efficacy. Here, we aimed to investigate mifamurtide efficacy through in vitro and in vivo experiments. Our results led us to identify a new possible target useful to improve mifamurtide effectiveness on metastatic OS: the cytokine interleukin-10 (IL-10). We provide experimental evidence that the synergic use of an anti-IL-10 antibody in combination with mifamurtide causes a significantly increased mortality rate in highest-grade OS cells and lower metastasis in an in vivo model compared with mifamurtide alone. Overall, our data suggest that mifamurtide in combination with an anti-IL-10 antibody could be proposed as a new treatment protocol to be studied to improve the outcomes of OS patients.

ß3-adrenergic receptor on tumor-infiltrating lymphocytes sustains IFN-γ-dependent PD-L1 expression and impairs anti-tumor immunity in neuroblastoma.

Neuroblastoma (NB) is a heterogeneous extracranial tumor occurring in childhood. A distinctive feature of NB tumors is their neuroendocrine ability to secrete catecholamines, which in turn, via ß-adrenergic receptors ligation, may affect different signaling pathways in tumor microenvironment (TME). It was previously demonstrated that specific antagonism of ß3-adrenergic receptor (ß3-AR) on NB tumor cells affected tumor growth and progression. Here, in a murine syngeneic model of NB, we aimed to investigate whether the ß3-AR modulation influenced the host immune system response against tumor. Results demonstrated that ß3-AR antagonism lead to an immune response reactivation, partially dependent on the PD-1/PD-L1 signaling axis involvement. Indeed, ß3-AR blockade on tumor-infiltrating lymphocytes (TILs) dampened their ability to secrete IFN-γ, which in turn reduced the PD-L1 expression, caused by TILs infiltration, on NB tumor cells. Further investigations, through a genomic analysis on NB patients, showed that high ADRB3 gene expression correlates with worse clinical outcome compared to the low expression group, and that ADRB3 gene expression affects different immune-related pathways. Overall, results indicate that ß3-AR in NB TME is able to modulate the interaction between tumor and host immune system, and that its antagonism hits multiple pro-tumoral signaling pathways.

ß2-and ß3-Adrenergic Receptors Contribute to Cancer-Evoked Pain in a Mouse Model of Osteosarcoma via Modulation of Neural Macrophages.

The mechanisms involved in the development and maintenance of cancer pain remain largely unidentified. Recently, it has been reported that ß-adrenergic receptors (ß-ARs), mainly ß2-and ß3-ARs, contribute to tumor proliferation and progression and may favor cancer-associated pain and neuroinflammation. However, the mechanism underlying ß-ARs in cancer pain is still unknown. Here, we investigated the role of ß1-, ß2-and ß3-ARs in a mouse model of cancer pain generated by the para-tibial injection of K7M2 osteosarcoma cells. Results showed a rapid tumor growth in the soft tissue associated with the development of mechanical allodynia in the hind paw ipsilateral to the injected site. In addition to reduce tumor growth, both propranolol and SR59230A, ß1-/ß2-and ß3-AR antagonists, respectively, attenuated mechanical allodynia, the number of macrophages and an oxidative stress by-product accumulated in the ipsilateral tibial nerve. The selective ß1-AR antagonist atenolol was able to slightly reduce the tumor growth but showed no effect in reducing the development of mechanical allodynia. Results suggest that the development of the mechanical allodynia in K7M2 osteosarcoma-bearing mice is mediated by oxidative stress associated with the recruitment of neural macrophages, and that antagonism of ß2-and ß3-ARs contribute not solely to the reduction of tumor growth, but also in cancer pain. Thus, the targeting of the ß2-and ß3-ARs signaling may be a promising therapeutic strategy against both tumor progression and the development of cancer-evoke pain in osteosarcoma.

ß3-Adrenoceptors as Putative Regulator of Immune Tolerance in Cancer and Pregnancy.

Understanding the mechanisms of immune tolerance is currently one of the most important challenges of scientific research. Pregnancy affects the immune system balance, leading the host to tolerate embryo alloantigens. Previous reports demonstrated that ß-adrenergic receptor (ß-AR) signaling promotes immune tolerance by modulation of NK and Treg, mainly through the activation of ß2-ARs, but recently we have demonstrated that also ß3-ARs induce an immune-tolerant phenotype in mice bearing melanoma. In this report, we demonstrate that ß3-ARs support host immune tolerance in the maternal microenvironment by modulating the same immune cells populations as recently demonstrated in cancer. Considering that ß3-ARs are modulated by oxygen levels, we hypothesize that hypoxia, through the upregulation of ß3-AR, promotes the biological shift toward a tolerant immunophenotype and that this is the same trick that embryo and cancer use to create an aura of immune-tolerance in a competent immune environment. This study confirms the analogies between fetal development and tumor progression and suggests that the expression of ß3-ARs represents one of the strategies to induce fetal and tumor immune tolerance.

Beta-Blockers and Berberine: A Possible Dual Approach to Contrast Neuroblastoma Growth and Progression.

The use of nutraceuticals during cancer treatment is a long-lasting debate. Berberine (BBR) is an isoquinoline quaternary alkaloid extracted from a variety of medicinal plants. BBR has been shown to have therapeutic effects in different pathologies, particularly in cancer, where it affects pathways involved in tumor progression. In neuroblastoma, the most common extracranial childhood solid tumor, BBR, reduces tumor growth by regulating both stemness and differentiation features and by inducing apoptosis. At the same time, the inhibition of ß-adrenergic signaling leads to a reduction in growth and increase of differentiation of neuroblastoma. In this review, we summarize the possible beneficial effects of BBR in counteracting tumor growth and progression in various types of cancer and, in particular, in neuroblastoma. However, BBR administration, besides its numerous beneficial effects, presents a few side effects due to inhibition of MAO A enzyme in neuroblastoma cells. Therefore, herein, we proposed a novel therapeutic strategy to overcome side effects of BBR administration consisting of concomitant administration of BBR together with ß-blockers in neuroblastoma.

ß3-Adrenoreceptor Blockade Induces Stem Cells Differentiation in Melanoma Microenvironment.

Although there is an increasing evidence that cancer stem cell (CSC) niches in the tumor microenvironment (TME) plays a crucial role in sustaining solid tumors progression, several molecular players involved in this regulation still remain unknown. The role of ß-adrenergic signaling in enhancing tumor growth through ß2-adrenoreceptors (ß2-ARs) has been confirmed in different cancer models, but the role played by the ß3-adrenergic receptor (ß3-AR) has recently emerged. Previous studies showed that ß3-AR promotes cancer growth through the activation of different stromal cells in the TME, and leads to melanoma malignancy progression through inflammation, angiogenesis, and immunotolerance. Here we show that in B16 melanoma-bearing mice, the pharmacological ß3-AR blockade is able to reduce the expression of CSC markers, and to induce a differentiated phenotype of hematopoietic subpopulations in TME. In particular, cytofluorimetric analysis (FACS) of the tumor mass shows that ß3-AR antagonist SR59230A promotes hematopoietic differentiation as indicated by increased ratios of lymphoid/hematopoietic stem cells (HSCs) and of myeloid progenitor cells/HSCs, and increases the number of Ter119 and natural killer (NK) precursor cells, and of granulocyte precursors, indicating active hematopoiesis within the tumor tissue. Moreover, pharmacological antagonism of ß3-AR induces mesenchymal stem cell (MSC) differentiation into adipocytes subtracting a potential renewal of the stem compartment by these cells. Here we demonstrate that ß3-AR blockade in the TME by inducing the differentiation of different stromal cells at the expense of stemness traits could possibly have a favorable effect on the control of melanoma progression.

ß3-Adrenoreceptor Activity Limits Apigenin Efficacy in Ewing Sarcoma Cells: A Dual Approach to Prevent Cell Survival.

Ewing Sarcoma (ES) is an aggressive paediatric tumour where oxidative stress and antioxidants play a central role in cancer therapy response. Inhibiting antioxidants expression, while at the same time elevating intracellular reactive oxygen species (ROS) levels, have been proposed as a valid strategy to overcome ES cancer progression. Flavonoid intake can affect free radical and nutritional status in children receiving cancer treatment, but it is not clear if it can arrest cancer progression. In particular, apigenin may enhance the effect of cytotoxic chemotherapy by inducing cell growth arrest, apoptosis, and by altering the redox state of the cells. Little is known about the use of apigenin in paediatric cancer. Recently, ß3-adrenergic receptor (ß3-AR) antagonism has been proposed as a possible strategy in cancer therapy for its ability to induce apoptosis by increasing intracellular levels of ROS. In this study we show that apigenin induces cell death in ES cells by modulating apoptosis, but not increasing ROS content. Since ES cells are susceptible to an increased oxidative stress to reduce cell viability, here we demonstrate that administration of ß3-ARs antagonist, SR59230A, improves the apigenin effect on cell death, identifying ß3-AR as a potential discriminating factor that could address the use of apigenin in ES.

Spotlight on ROS and ß3-Adrenoreceptors Fighting in Cancer Cells.

The role of ROS and RNS is a long-standing debate in cancer. Increasing the concentration of ROS reaching the toxic threshold can be an effective strategy for the reduction of tumor cell viability. On the other hand, cancer cells, by maintaining intracellular ROS concentration at an intermediate level called "mild oxidative stress," promote the activation of signaling that favors tumor progression by increasing cell viability and dangerous tumor phenotype. Many chemotherapeutic treatments induce cell death by rising intracellular ROS concentration. The persistent drug stimulation leads tumor cells to simulate a process called hormesis by which cancer cells exhibit a biphasic response to exposure to drugs used. After a first strong response to a low dose of chemotherapeutic agent, cancer cells start to decrease the response even if high doses of drugs were used. In this framework, ß3-adrenoreceptors (ß3-ARs) fit with an emerging antioxidant role in cancer. ß3-ARs are involved in tumor proliferation, angiogenesis, metastasis, and immune tolerance. Its inhibition, by the selective ß3-ARs antagonist (SR59230A), leads cancer cells to increase ROS concentration thus inducing cell death and to decrease NO levels thus inhibiting angiogenesis. In this review, we report an overview on reactive oxygen biology in cancer cells focusing on ß3-ARs as new players in the antioxidant pathway.