Targeting the β2 -adrenergic receptor increases chemosensitivity in multiple myeloma by induction of apoptosis and modulating cancer cell metabolism

G-protein coupled receptors in metabolic reprogramming and cancer

G-protein coupled receptors (GPCR) are one of the frequently investigated drug targets. GPCRs are involved in many human pathophysiologies that lead to various disease conditions, such as cancer, diabetes, and obesity. GPCR receptor activates multiple signaling pathways depending on the ligand and tissue type. However, this review will be limited to the GPCR-mediated metabolic modulations and the activation of relevant signaling pathways in cancer therapy. Cancer cells often have reprogrammed cell metabolism to support tumor growth and metastatic plasticity. Many aggressive cancer cells maintain a hybrid metabolic status, using both glycolysis and mitochondrial metabolism for better metabolic plasticity. In addition to glucose and glutamine pathways, fatty acid is a key mitochondrial energy source in some cancer subtypes. Recently, targeting alternative energy pathways like fatty acid beta-oxidation (FAO) has attracted great interest in cancer therapy. Several in vitro and in vivo experiments in different cancer models reported encouraging responses to FAO inhibitors. However, due to the potential liver toxicity of FAO inhibitors in clinical trials, new approaches to indirectly target metabolic reprogramming are necessary for in vivo targeting of cancer cells. This review specifically focused on free fatty acid receptors (FFAR) and β-adrenergic receptors (β-AR) because of their reported significance in mitochondrial metabolism and cancer. Further understanding the pharmacology of GPCRs and their role in cancer metabolism will help repurpose GPCR-targeting drugs for cancer therapy and develop novel drug discovery strategies to combine them with standard cancer therapy to increase anticancer potential and overcome drug resistance.

Escitalopram facilitates tumor growth and metastasis in rodents: Is it safe?

Cancer patients are often treated perioperatively with serotonin reuptake inhibitors (SSRIs) to counteract anxiety and depression. Recent studies suggest that long-term cancer outcomes may also be affected by SSRI use in an agent-dependent manner. Importantly, the perioperative use of SSRIs is prevalent clinically, but has rarely been studied empirically. Herein, we studied escitalopram, a commonly prescribed SSRI in cancer patients, in vitro, and in vivo in the context of surgery and/or cancer progression in immune-competent rodents, employing the Panc02 (pancreatic), MADB106, 4T1, EO771 (mammary), and CT26 (colon) syngeneic tumor models, assessing primary tumor growth and metastasis. Escitalopram (10-15mg/kg/day, 14-30 days) was administered along tumor and/or metastatic progression, via intraperitoneal injections, Alzet osmotic pumps, or drinking water. In vitro, escitalopram affected proliferation rates in a cell-line-, dose-, and exposure duration- dependent manner, mostly increasing or not affecting proliferation. In contrast, in vivo escitalopram consistently increased primary tumor growth, and experimental and spontaneous metastasis in all models tested. In pancreatic tumor-bearing mice, escitalopram increased tumor growth in two different studies by ∼1.5-fold, as indicated by bioluminescence imaging. In the mammary primary tumor models, escitalopram increased 4T1 and EO771 growth by 1.4 to 2.2-fold. Last, escitalopram increased experimental MADB106 lung metastasis and CT26 liver metastasis, as well as spontaneous post-excision 4T1 lung metastasis by 1.6 to 2.3-fold. Taken together, although additional research is needed to elucidate mediating in vivo mechanisms, and to assess clinical oncological risks of escitalopram, these findings raise concerns regarding the prevalent perioperative use of escitalopram in cancer patients.

Unraveling the peripheral nervous System's role in tumor: A Double-edged Sword

The peripheral nervous system (PNS) includes all nerves outside the brain and spinal cord, comprising various cells like neurons and glial cells, such as schwann and satellite cells. The PNS is increasingly recognized for its bidirectional interactions with tumors, exhibiting both pro- and anti-tumor effects. Our review delves into the complex mechanisms underlying these interactions, highlighting recent findings that challenge the conventional understanding of PNS's role in tumorigenesis. We emphasize the contradictory results in the literature and propose novel perspectives on how these discrepancies can be resolved. By focusing on the PNS's influence on tumor initiation, progression, and microenvironment remodeling, we provide a comprehensive analysis that goes beyond the structural description of the PNS. Our review suggests that a deeper comprehension of the PNS-tumor crosstalk is pivotal for developing targeted anticancer strategies. We conclude by emphasizing the need for future research to unravel the intricate dynamics of the PNS in cancer, which may lead to innovative diagnostic tools and therapeutic approaches.

Neuroscience in peripheral cancers: tumors hijacking nerves and neuroimmune crosstalk

Cancer neuroscience is an emerging field that investigates the intricate relationship between the nervous system and cancer, gaining increasing recognition for its importance. The central nervous system governs the development of the nervous system and directly affects brain tumors, and the peripheral nervous system (PNS) shapes the tumor microenvironment (TME) of peripheral tumors. Both systems are crucial in cancer initiation and progression, with recent studies revealing a more intricate role of the PNS within the TME. Tumors not only invade nerves but also persuade them through remodeling to further promote malignancy, creating a bidirectional interaction between nerves and cancers. Notably, immune cells also contribute to this communication, forming a triangular relationship that influences protumor inflammation and the effectiveness of immunotherapy. This review delves into the intricate mechanisms connecting the PNS and tumors, focusing on how various immune cell types influence nerve‒tumor interactions, emphasizing the clinical relevance of nerve‒tumor and nerve‒immune dynamics. By deepening our understanding of the interplay between nerves, cancer, and immune cells, this review has the potential to reshape tumor biology insights, inspire innovative therapies, and improve clinical outcomes for cancer patients.

Targeting mTOR signaling pathways in multiple myeloma: biology and implication for therapy

Multiple Myeloma (MM), a cancer of terminally differentiated plasma cells, is the second most prevalent hematological malignancy and is incurable due to the inevitable development of drug resistance. Intense protein synthesis is a distinctive trait of MM cells, supporting the massive production of clonal immunoglobulins or free light chains. The mammalian target of rapamycin (mTOR) kinase is appreciated as a master regulator of vital cellular processes, including regulation of metabolism and protein synthesis, and can be found in two multiprotein complexes, mTORC1 and mTORC2. Dysregulation of these complexes is implicated in several types of cancer, including MM. Since mTOR has been shown to be aberrantly activated in a large portion of MM patients and to play a role in stimulating MM cell survival and resistance to several existing therapies, understanding the regulation and functions of the mTOR complexes is vital for the development of more effective therapeutic strategies. This review provides a general overview of the mTOR pathway, discussing key discoveries and recent insights related to the structure and regulation of mTOR complexes. Additionally, we highlight findings on the mechanisms by which mTOR is involved in protein synthesis and delve into mTOR-mediated processes occurring in MM. Finally, we summarize the progress and current challenges of drugs targeting mTOR complexes in MM.

Effects of chronic stress on cancer development and the therapeutic prospects of adrenergic signaling regulation

Long-term chronic stress is an important factor in the poor prognosis of cancer patients. Chronic stress reduces the tissue infiltration of immune cells in the tumor microenvironment (TME) by continuously activating the adrenergic signaling, inhibits antitumor immune response and tumor cell apoptosis while also inducing epithelial-mesenchymal transition (EMT) and tumor angiogenesis, promoting tumor invasion and metastasis. This review first summarizes how adrenergic signaling activates intracellular signaling by binding different adrenergic receptor (AR) heterodimers. Then, we focused on reviewing adrenergic signaling to regulate multiple functions of immune cells, including cell differentiation, migration, and cytokine secretion. In addition, the article discusses the mechanisms by which adrenergic signaling exerts pro-tumorigenic effects by acting directly on the tumor itself. It also highlights the use of adrenergic receptor modulators in cancer therapy, with particular emphasis on their potential role in immunotherapy. Finally, the article reviews the beneficial effects of stress intervention measures on cancer treatment. We think that enhancing the body's antitumor response by adjusting adrenergic signaling can enhance the efficacy of cancer treatment.

G protein-coupled receptor-mediated autophagy in health and disease

G protein-coupled receptors (GPCRs) constitute the largest and most diverse superfamily of mammalian transmembrane proteins. These receptors are involved in a wide range of physiological functions and are targets for more than a third of available drugs in the market. Autophagy is a cellular process involved in degrading damaged proteins and organelles and in recycling cellular components. Deficiencies in autophagy are involved in a variety of pathological conditions. Both GPCRs and autophagy are essential in preserving homeostasis and cell survival. There is emerging evidence suggesting that GPCRs are direct regulators of autophagy. Additionally, autophagic machinery is involved in the regulation of GPCR signalling. The interplay between GPCR and autophagic signalling mechanisms significantly impacts on health and disease; however, there is still an incomplete understanding of the underlying mechanisms and therapeutic implications in different tissues and disease contexts. This review aims to discuss the interactions between GPCR and autophagy signalling. Studies on muscarinic receptors, beta-adrenoceptors, taste receptors, purinergic receptors and adhesion GPCRs are summarized, in relation to autophagy.

Repurposing beta-blockers for combinatory cancer treatment: effects on conventional and immune therapies

Beta-adrenergic receptor signaling regulates cellular processes associated with facilitating tumor cell proliferation and dampening anti-tumor immune response. These cellular processes may lead to compromised tumor control and cancer progression. Based on this ramification, Beta-blockers (BBs) have emerged as a potential treatment by inhibiting beta-adrenergic receptor signaling. This review aimed to investigate the relationship between the use of BBs and tumor progression and treatment response. Therefore, the authors explored several aspects: the potential synergistic relationship of BBs with chemotherapy and immunotherapy in enhancing the effectiveness of chemotherapeutic and immunotherapeutic treatments and their role in boosting endogenous immunity. Further, this review explores the distinctions between the major types of BBs: Non-selective Beta Blockers (NSBBs) and Selective Beta Blockers (SBBs), and their contributions to combinatory cancer treatment. In this review, we presented a perspective interpretation of research findings and future directions. Overall, this review discusses the potential and challenge that BBs present in improving the effectiveness and outcome of cancer treatment.

Trial watch: beta-blockers in cancer therapy

Compelling evidence supports the hypothesis that stress negatively impacts cancer development and prognosis. Irrespective of its physical, biological or psychological source, stress triggers a physiological response that is mediated by the hypothalamic-pituitary-adrenal axis and the sympathetic adrenal medullary axis. The resulting release of glucocorticoids and catecholamines into the systemic circulation leads to neuroendocrine and metabolic adaptations that can affect immune homeostasis and immunosurveillance, thus impairing the detection and eradication of malignant cells. Moreover, catecholamines directly act on β-adrenoreceptors present on tumor cells, thereby stimulating survival, proliferation, and migration of nascent neoplasms. Numerous preclinical studies have shown that blocking adrenergic receptors slows tumor growth, suggesting potential clinical benefits of using β-blockers in cancer therapy. Much of these positive effects of β-blockade are mediated by improved immunosurveillance. The present trial watch summarizes current knowledge from preclinical and clinical studies investigating the anticancer effects of β-blockers either as standalone agents or in combination with conventional antineoplastic treatments or immunotherapy.

Ginsenoside Rh4 inhibits the malignant progression of multiple myeloma and induces ferroptosis by regulating SIRT2

Multiple myeloma (MM) has a high mortality rate, and the exploration of therapeutic drugs for MM with low side effects is a hot topic at the moment. Ginsenoside Rh4 has been shown to inhibit tumour growth in many cancers. However, the role of ginsenoside Rh4 in MM and its reaction mechanism have not been reported so far. After the treatment with different concentrations of ginsenoside Rh4, the proliferation of NCI-H929 cells was detected by Cell Counting Kit-8 and 5-ethynyl-2'-deoxyuridine staining. The cell apoptosis and cycle arrest were detected by flow cytometry and western blot. The thiobarbituric acid-reactive substances (TBARS) production was assessed with TBARS assay, whereas Fe²⁺ fluorescence assay was used for the measurement of Fe²⁺ level. The production of reactive oxygen species was evaluated with dichloro-dihydro-fluorescein diacetate staining, and western blot was applied for the estimation of ferroptosis-related proteins. The potential targets of ginsenoside Rh4 were predicted by molecular docking technology and verified by western blot. The transfection efficacy of overexpression-SIRT2 was examined with quantitative reverse transcription polymerase chain reaction and western blot. To figure out the detailed reaction mechanism between ginsenoside Rh4 and SIRT2 in MM, rescue experiments were conducted. We found that ginsenoside Rh4 inhibited cell proliferation, induced cell apoptosis, promoted cycle arrest and facilitated ferroptosis in MM. Moreover, ginsenoside Rh4 inhibited SIRT2 expression in MM cells. The overexpression of SIRT2 reversed the effects of ginsenoside Rh4 on cell proliferation, cell apoptosis, cycle arrest and ferroptosis in MM. Overall, ginsenoside Rh4 inhibited the malignant progression of MM and induced ferroptosis by regulating SIRT2.

Drug Repurposing in Oncology: A Systematic Review of Randomized Controlled Clinical Trials

Quality pharmacological treatment can improve survival in many types of cancer. Drug repurposing offers advantages in comparison with traditional drug development procedures, reducing time and risk. This systematic review identified the most recent randomized controlled clinical trials that focus on drug repurposing in oncology. We found that only a few clinical trials were placebo-controlled or standard-of-care-alone-controlled. Metformin has been studied for potential use in various types of cancer, including prostate, lung, and pancreatic cancer. Other studies assessed the possible use of the antiparasitic agent mebendazole in colorectal cancer and of propranolol in multiple myeloma or, when combined with etodolac, in breast cancer. We were able to identify trials that study the potential use of known antineoplastics in other non-oncological conditions, such as imatinib for severe coronavirus disease in 2019 or a study protocol aiming to assess the possible repurposing of leuprolide for Alzheimer's disease. Major limitations of these clinical trials were the small sample size, the high clinical heterogeneity of the participants regarding the stage of the neoplastic disease, and the lack of accounting for multimorbidity and other baseline clinical characteristics. Drug repurposing possibilities in oncology must be carefully examined with well-designed trials, considering factors that could influence prognosis.