Further data on beta-blockers and cancer risk: observational study and meta-analysis of randomized clinical trials

Long-term exposure to antihypertensive drugs and the risk of cancer occurrence: evidence from a large population-based study

OBJECTIVE

Available data on the association between antihypertensive drugs and cancer are characterized by a few years follow-up. Our aim has been to evaluate the association between long-term exposure to antihypertensive drugs and the risk of cancer occurrence.

METHODS

Using the healthcare utilization databases of the Lombardy region (Italy), individuals aged 40-85 years who had no previous history of cancer and were newly dispensed with at least one antihypertensive drug from the major drug classes between 2009 and 2011 were followed from the first drug dispensation to December 31, 2020. Data were analyzed according to the first drug used and the intention to treat principle, but also via an "as treated" approach, that is, by considering changes of and exposure to drugs during follow-up. The association between the duration of exposure to each drug class and the risk of cancer occurrence was evaluated using the adjusted Cox regression models.

RESULTS

The study cohort included 338 910 new drug users (median age, 59 years; 49.5% males). During a median follow-up of 10.2 years, 36 556 cancers occurred. There was no consistent significant association between the risk of cancer occurrence and angiotensin-converting-enzyme inhibitors, angiotensin-receptor blockers, or thiazides. A progressive, weak increase in cancer occurrence was associated with progressive exposure to calcium channel blockers and, limited to long-term exposure, to beta-blockers. A modest progressive increase in risk was observed also for thiazide-like and loop diuretics in the as treated, although not in the intention to treat approach.

CONCLUSIONS

Long-term evaluation of exposure to antihypertensive drugs did not show consistent associations between thiazides, angiotensin-receptor blockers, or angiotensin-converting-enzyme inhibitors and the risk of cancer occurrence. A weak association was observed between cancer and the duration of exposure to calcium channel blockers and beta-blockers.

Heart failure pharmacotherapy and cancer: pathways and pre-clinical/clinical evidence

Heart failure (HF) patients have a significantly higher risk of new-onset cancer and cancer-associated mortality, compared to subjects free of HF. While both the prevention and treatment of new-onset HF in patients with cancer have been investigated extensively, less is known about the prevention and treatment of new-onset cancer in patients with HF, and whether and how guideline-directed medical therapy (GDMT) for HF should be modified when cancer is diagnosed in HF patients. The purpose of this review is to elaborate and discuss the effects of pillar HF pharmacotherapies, as well as digoxin and diuretics on cancer, and to identify areas for further research and novel therapeutic strategies. To this end, in this review, (i) proposed effects and mechanisms of action of guideline-directed HF drugs on cancer derived from pre-clinical data will be described, (ii) the evidence from both observational studies and randomized controlled trials on the effects of guideline-directed medical therapy on cancer incidence and cancer-related outcomes, as synthetized by meta-analyses will be reviewed, and (iii) considerations for future pre-clinical and clinical investigations will be provided.

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.

Beta-adrenergic receptor blockers and hepatocellular carcinoma survival: a systemic review and meta-analysis

INTRODUCTION

Preclinical data have revealed that beta-adrenergic stimulation can affect the growth and progression of different types of malignancies. Beta-adrenergic receptor blockers have been associated with improved survival in patients with many types of cancer. We performed a meta-analysis to investigate the association between beta-blocker use and hepatocellular carcinoma (HCC) prognosis.

METHODS

In this meta-analysis, a full search was conducted using PubMed, the Cochrane library and Embase to identify all relevant studies published up to May 2021. Available hazard ratios (HRs) were extracted for overall survival (OS), cancer-specific survival (CSS) and pooled using a random-effects meta-analysis.

RESULTS

Four studies involving 7252 patients with HCC met the inclusion criteria and were included in the systemic review. Three studies that reported OS data of 5148 patients were included in the meta-analysis. The random-effects model showed that beta-blocker use was associated with significantly improved OS in HCC (HR = 0.69, 95% CI = 0.54-0.88, P = 0.0031), without significant heterogeneity (I² = 41%; Q = 6.42, P = 0.18).

CONCLUSION

This meta-analysis suggested that beta-blocker use can be associated with prolonged OS of patients with HCC.

Genetically proxied therapeutic inhibition of antihypertensive drug targets and risk of common cancers: A mendelian randomization analysis

BACKGROUND

Epidemiological studies have reported conflicting findings on the potential adverse effects of long-term antihypertensive medication use on cancer risk. Naturally occurring variation in genes encoding antihypertensive drug targets can be used as proxies for these targets to examine the effect of their long-term therapeutic inhibition on disease outcomes.

METHODS AND FINDINGS

We performed a mendelian randomization analysis to examine the association between genetically proxied inhibition of 3 antihypertensive drug targets and risk of 4 common cancers (breast, colorectal, lung, and prostate). Single-nucleotide polymorphisms (SNPs) in ACE, ADRB1, and SLC12A3 associated (P < 5.0 × 10-8) with systolic blood pressure (SBP) in genome-wide association studies (GWAS) were used to proxy inhibition of angiotensin-converting enzyme (ACE), β-1 adrenergic receptor (ADRB1), and sodium-chloride symporter (NCC), respectively. Summary genetic association estimates for these SNPs were obtained from GWAS consortia for the following cancers: breast (122,977 cases, 105,974 controls), colorectal (58,221 cases, 67,694 controls), lung (29,266 cases, 56,450 controls), and prostate (79,148 cases, 61,106 controls). Replication analyses were performed in the FinnGen consortium (1,573 colorectal cancer cases, 120,006 controls). Cancer GWAS and FinnGen consortia data were restricted to individuals of European ancestry. Inverse-variance weighted random-effects models were used to examine associations between genetically proxied inhibition of these drug targets and risk of cancer. Multivariable mendelian randomization and colocalization analyses were employed to examine robustness of findings to violations of mendelian randomization assumptions. Genetically proxied ACE inhibition equivalent to a 1-mm Hg reduction in SBP was associated with increased odds of colorectal cancer (odds ratio (OR) 1.13, 95% CI 1.06 to 1.22; P = 3.6 × 10-4). This finding was replicated in the FinnGen consortium (OR 1.40, 95% CI 1.02 to 1.92; P = 0.035). There was little evidence of association of genetically proxied ACE inhibition with risk of breast cancer (OR 0.98, 95% CI 0.94 to 1.02, P = 0.35), lung cancer (OR 1.01, 95% CI 0.92 to 1.10; P = 0.93), or prostate cancer (OR 1.06, 95% CI 0.99 to 1.13; P = 0.08). Genetically proxied inhibition of ADRB1 and NCC were not associated with risk of these cancers. The primary limitations of this analysis include the modest statistical power for analyses of drug targets in relation to some less common histological subtypes of cancers examined and the restriction of the majority of analyses to participants of European ancestry.

CONCLUSIONS

In this study, we observed that genetically proxied long-term ACE inhibition was associated with an increased risk of colorectal cancer, warranting comprehensive evaluation of the safety profiles of ACE inhibitors in clinical trials with adequate follow-up. There was little evidence to support associations across other drug target-cancer risk analyses, consistent with findings from short-term randomized controlled trials for these medications.

The Relationship Between Anti-Hypertensive Drugs and Cancer: Anxiety to be Resolved in Urgent

Hypertension is the prevailing independent risk factor for cardiovascular disease worldwide. Anti-hypertensive drugs are the common and effective cure for lowering blood pressure in patients with hypertension. However, some large-scale clinical studies have pointed out that long-term ingestion of some oral anti-hypertensive drugs was associated with risks of incident cancer and the survival time. In contrast, other studies argue that anti-hypertensive drugs are not related to the occurrence of cancer, even as a complementary therapy of tumor treatment. To resolve the dispute, numerous recent mechanistic studies using animal models have tried to find the causal link between cancer and different anti-hypertensive drugs. However, the results were often contradictory. Such uncertainties have taken a toll on hypertensive patients. In this review, we will summarize advances of longitudinal studies in the association between anti-hypertensive drugs and related tumor risks that have helped to move the field forward from associative to causative conclusions, in hope of providing a reference for more rigorous and evidence-based clinical research on the topic to guide the clinical decision making.

The Role of Non-Selective β-Blockers in Compensated Cirrhotic Patients without Major Complications

Background and Objectives: Non-selective β-blockers (NSBB) could prevent decompensation and hepatocellular carcinoma (HCC) in cirrhotic patients with clinically significant portal hypertension (CSPH), but remained uncertain for compensated cirrhotic patients without major complications. We aimed to compare the clinical outcomes between propranolol users and non-users of a CC group without major complications. Material and Methods: We conducted this population-based cohort study by using the Taiwanese Longitudinal Health Insurance Database 2000. Propranolol users (classified as cumulative defined daily dose (cDDD)) and non-PPL users were matched with a 1:1 propensity score in both cohorts. Results: This study comprised 6896 propranolol users and 6896 non-propranolol users. There was no significant impact on the development of spontaneous bacterial peritonitis between the two groups (aHR: 1.24, 95% confidence interval (CI): 0.88~1.75; p = 0.2111). Male gender, aged condition, and non-liver related diseases (peripheral vascular disease, cerebrovascular disease, dementia, pulmonary disease, and renal disease) were the independent risk factors of mortality. PPL users had significantly lower incidence of HCC development than non-users (aHR: 0.81, p = 0.0580; aHR: 0.80, p = 0.1588; and aHR: 0.49, p < 0.0001 in the groups of 1–28, 29–90, and >90 cDDD, respectively). Conclusion: The current study suggested that high cumulative doses of propranolol could decrease the risk of hepatocellular carcinoma among compensated cirrhotic patients without major complications. Further large-scale prospective studies are still required to confirm the findings in this study. Results: It remained uncertain whether non-selective β-blockers (NSBB) could prevent decompensation and hepatocellular carcinoma (HCC) in compensatory cirrhotic patients without major complications. This study aimed to compare the clinical outcomes between propranolol users and non-users of the CC group without major complications.

Cancer Chemoprevention: Preclinical In Vivo Alternate Dosing Strategies to Reduce Drug Toxicities

Cancer chemopreventive agents inhibit the formation of precursor lesions and/or the progression of these lesions to late stage disease. This approach to disease control has the potential to reduce the physical and financial costs of cancer in society. Several drugs that have been approved by the FDA for other diseases and have been extensively evaluated for their safety and pharmacokinetic/pharmacodynamic characteristics have the potential to be repurposed for use as cancer chemopreventive agents. These agents often mechanistically inhibit signaling molecules that play key roles in the carcinogenic process. The safety profile of agents is a primary concern when considering the administration of drugs for chemoprevention, as the drugs will be given chronically to high-risk, asymptomatic individuals. To decrease drug toxicity while retaining efficacy, several approaches are currently being explored. In this short review, we describe studies that use preclinical in vivo models to assess efficacy of alternative drug dosing strategies and routes of drug administration on chemopreventive drug efficacy. In vivo drug dosing strategies that reduce toxicity while retaining efficacy will pave the way for future cancer prevention clinical trials.

The effect of propranolol on the prognosis of hepatocellular carcinoma: A nationwide population-based study

Background

Beta-blockers can reduce recurrence, metastasis, and mortality in various cancers. In this study, we investigated the effect of propranolol, a non-selective beta-blocker on overall survival (OS) in unresectable/metastatic hepatocellular carcinoma (HCC) and on recurrence-free survival (RFS) in resectable, curable HCC.

Methods

Data were retrieved from the Taiwan National Health Insurance Research Database between January 2000 and December 2013. Propranolol users (for >1 year) and non-propranolol users were matched using a 1:2 propensity score in both cohorts.

Results

The unresectable/metastatic HCC cohort comprised 1,560 propranolol users and 3,120 non-propranolol users (control group). On multivariate Cox regression analysis of HCC mortality, propranolol significantly reduced the mortality risk by 22% (hazard ratio [HR] = 0.78, 95% confidence interval [CI] 0.72–0.84, P <0.001). On stratified Cox regression analysis, propranolol also reduced the mortality risk in HCC patients with hepatitis B (HR = 0.92, 95% CI 0.85–0.99, P = 0.045), hepatitis C (HR = 0.85, 95% CI = 0.78–0.92, P = 0.001), liver cirrhosis (HR = 0.78, 95% CI = 0.72–0.85, P <0.001), and diabetes mellitus (HR = 0.87, 95% CI = 0.81–0.94, P = 0.008). The resectable, curable HCC cohort comprised 289 propranolol users and 578 non-propranolol users (control group), but there was no significant difference in RFS (P = 0.762) between propranolol and non-propranolol users.

Conclusion

This study revealed that propranolol could improve OS in unresectable/metastatic HCC.

Sympathetic innervation contributes to perineural invasion of salivary adenoid cystic carcinoma via the β2-adrenergic receptor

Purpose

Perineural invasion (PNI) is reported to correlate with local recurrence and poor prognosis of salivary adenoid cystic carcinoma (SACC). However, the pathogenesis of PNI remains unclear. The aims of this study were to investigate the correlation between sympathetic innervation and SACC PNI and to elucidate how the sympathetic neurotransmitter norepinephrine (NE) regulates the PNI process.

Materials and methods

Sympathetic innervation and β2-adrenergic receptor (β2-AR) expression in SACC tissues were evaluated by immunohistochemistry. The NE concentrations in SACC tissues and dorsal root ganglia (DRG) coculture models were measured by ELISA. β2-AR expression in SACC cells was detected by performing quantitative real-time polymerase chain reaction (qRT-PCR) and immunofluorescence assay. SACC cells were treated with NE, the nonselective α-AR blocker phentolamine, the β2-AR antagonist ICI118,551, or were transfected with β2-AR small interfering RNA (siRNA). Proliferation was evaluated in methyl thiazolyl tetrazolium assay, and migration was evaluated in Transwell assay and wound-healing assay. PNI was tested through both Transwell assay and a DRG coculture model. The expressions of epithelial–mesenchymal transition (EMT) markers and matrix metalloproteinases (MMPs) were measured by performing qRT-PCR and Western blot assay.

Results

Sympathetic innervation and β2-AR were highly distributed in SACC tissues and correlated positively with PNI (P=0.035 and P=0.003, respectively). The sympathetic neurotransmitter NE was overexpressed in SACC tissues and DRG coculture models. Exogenously added NE promoted proliferation, migration, and PNI of SACC cells via β2-AR activation. NE/β2-AR signaling may promote proliferation, migration, and PNI by inducing EMT and upregulating MMPs. However, β2-AR inhibition with either an antagonist or siRNA abrogated NE-induced PNI.

Conclusion

Collectively, our findings reveal the supportive role of sympathetic innervation in the pathogenesis of SACC PNI and suggest β2-AR as a potential therapeutic target for treating PNI in SACC.

Smoking-associated lung cancer prevention by blockade of the beta-adrenergic receptor-mediated insulin-like growth factor receptor activation

Activation of receptor tyrosine kinases (RTKs) is associated with carcinogenesis, but its contribution to smoking-associated lung carcinogenesis is poorly understood. Here we show that a tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced insulin-like growth factor 1 receptor (IGF-1R) activation via β-adrenergic receptor (β-AR) is crucial for smoking-associated lung carcinogenesis. Treatment with NNK stimulated the IGF-1R signaling pathway in a time- and dose-dependent manner, which was suppressed by pharmacological or genomic blockade of β-AR and the downstream signaling including a Gβγ subunit of β-AR and phospholipase C (PLC). Consistently, β-AR agonists led to increased IGF-1R phosphorylation. The increase in IGF2 transcription via β-AR, signal transducer and activator of transcription 3 (STAT3), and nuclear factor-kappa B (NF-κB) was associated with NNK-induced IGF-1R activation. Finally, treatment with β-AR antagonists suppressed the acquisition of transformed phenotypes in lung epithelial cells and lung tumor formation in mice. These results suggest that blocking β-AR-mediated IGF-1R activation can be an effective strategy for lung cancer prevention in smokers.

Adrenergic Signaling: A Targetable Checkpoint Limiting Development of the Antitumor Immune Response

An immune response must be tightly controlled so that it will be commensurate with the level of response needed to protect the organism without damaging normal tissue. The roles of cytokines and chemokines in orchestrating these processes are well known, but although stress has long been thought to also affect immune responses, the underlying mechanisms were not as well understood. Recently, the role of nerves and, specifically, the sympathetic nervous system, in regulating immune responses is being revealed. Generally, an acute stress response is beneficial but chronic stress is detrimental because it suppresses the activities of effector immune cells while increasing the activities of immunosuppressive cells. In this review, we first discuss the underlying biology of adrenergic signaling in cells of both the innate and adaptive immune system. We then focus on the effects of chronic adrenergic stress in promoting tumor growth, giving examples of effects on tumor cells and immune cells, explaining the methods commonly used to induce stress in preclinical mouse models. We highlight how this relates to our observations that mandated housing conditions impose baseline chronic stress on mouse models, which is sufficient to cause chronic immunosuppression. This problem is not commonly recognized, but it has been shown to impact conclusions of several studies of mouse physiology and mouse models of disease. Moreover, the fact that preclinical mouse models are chronically immunosuppressed has critical ramifications for analysis of any experiments with an immune component. Our group has found that reducing adrenergic stress by housing mice at thermoneutrality or treating mice housed at cooler temperatures with β-blockers reverses immunosuppression and significantly improves responses to checkpoint inhibitor immunotherapy. These observations are clinically relevant because there are numerous retrospective epidemiological studies concluding that cancer patients who were taking β-blockers have better outcomes. Clinical trials testing whether β-blockers can be repurposed to improve the efficacy of traditional and immunotherapies in patients are on the horizon.

Screening a small molecule library to identify inhibitors of NF-κB inducing kinase and pro-labor genes in human placenta

The non-canonical NF-κB signaling (RelB/p52) pathway drives pro-labor genes in the human placenta, including corticotropin-releasing hormone (CRH) and cyclooxygenase-2 (COX-2), making this a potential therapeutic target to delay onset of labor. Here we sought to identify small molecule compounds from a pre-existing chemical library of orally active drugs that can inhibit this NF-κB signaling, and in turn, human placental CRH and COX-2 production. We used a cell-based assay coupled with a dual-luciferase reporter system to perform an in vitro screening of a small molecule library of 1,120 compounds for inhibition of the non-canonical NF-κB pathway. Cell toxicity studies and drug efflux transport MRP1 assays were used to further characterize the lead compounds. We have found that 14 drugs have selective inhibitory activity against lymphotoxin beta complex-induced activation of RelB/p52 in HEK293T cells, several of which also inhibited expression of CRH and COX-2 in human term trophoblast. We identified sulfapyridine and propranolol with activity against CRH and COX-2 that deserve further study. These drugs could serve as the basis for development of orally active drugs to affect length of gestation, first in an animal model, and then in clinical trials to prevent preterm birth during human pregnancy.

Stress hormones promote EGFR inhibitor resistance in NSCLC: Implications for combinations with β-blockers

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) resistance mediated by T790M-independent mechanisms remains a major challenge in the treatment of non-small cell lung cancer (NSCLC). We identified a targetable mechanism of EGFR inhibitor resistance whereby stress hormones activate β2-adrenergic receptors (β2-ARs) on NSCLC cells, which cooperatively signal with mutant EGFR, resulting in the inactivation of the tumor suppressor, liver kinase B1 (LKB1), and subsequently induce interleukin-6 (IL-6) expression. We show that stress and β2-AR activation promote tumor growth and EGFR inhibitor resistance, which can be abrogated with β-blockers or IL-6 inhibition. IL-6 was associated with a worse outcome in EGFR TKI-treated NSCLC patients, and β-blocker use was associated with lower IL-6 concentrations and improved benefit from EGFR inhibitors. These findings provide evidence that chronic stress hormones promote EGFR TKI resistance via β2-AR signaling by an LKB1/CREB (cyclic adenosine 3',5'-monophosphate response element-binding protein)/IL-6-dependent mechanism and suggest that combinations of β-blockers with EGFR TKIs merit further investigation as a strategy to abrogate resistance.

A Novel Effect of β-Adrenergic Receptor on Mammary Branching Morphogenesis and its Possible Implications in Breast Cancer

Understanding the mechanisms that govern normal mammary gland development is crucial to the comprehension of breast cancer etiology. β-adrenergic receptors (β-AR) are targets of endogenous catecholamines such as epinephrine that have gained importance in the context of cancer biology. Differences in β₂-AR expression levels may be responsible for the effects of epinephrine on tumor vs non-tumorigenic breast cell lines, the latter expressing higher levels of β₂-AR. To study regulation of the breast cell phenotype by β₂-AR, we over-expressed β₂-AR in MCF-7 breast cancer cells and knocked-down the receptor in non-tumorigenic MCF-10A breast cells. In MCF-10A cells having knocked-down β₂-AR, epinephrine increased cell proliferation and migration, similar to the response by tumor cells. In contrast, in MCF-7 cells overexpressing the β₂-AR, epinephrine decreased cell proliferation and migration and increased adhesion, mimicking the response of the non-tumorigenic MCF-10A cells, thus underscoring that β₂-AR expression level is a key player in cell behavior. β-adrenergic stimulation with isoproterenol induced differentiation of breast cells growing in 3-dimension cell culture, and also the branching of murine mammary epithelium in vivo. Branching induced by isoproterenol was abolished in fulvestrant or tamoxifen-treated mice, demonstrating that the effect of β-adrenergic stimulation on branching is dependent on the estrogen receptor (ER). An ER-independent effect of isoproterenol on lumen architecture was nonetheless found. Isoproterenol significantly increased the expression of ERα, Ephrine-B1 and fibroblast growth factors in the mammary glands of mice, and in MCF-10A cells. In a poorly differentiated murine ductal carcinoma, isoproterenol also decreased tumor growth and induced tumor differentiation. This study highlights that catecholamines, through β-AR activation, seem to be involved in mammary gland development, inducing mature duct formation. Additionally, this differentiating effect could be resourceful in a breast tumor context.

Digoxin and prostate cancer survival in the Finnish Randomized Study of Screening for Prostate Cancer

BACKGROUND

Protective effects have been suggested for digoxin against prostate cancer risk. However, few studies have evaluated the possible effects on prostate cancer-specific survival. We studied the association between use of digoxin or beta-blocker sotalol and prostate cancer-specific survival as compared with users of other antiarrhythmic drugs in a retrospective cohort study.

METHODS

Our study population consisted of 6537 prostate cancer cases from the Finnish Randomized Study of Screening for Prostate Cancer diagnosed during 1996-2009 (485 digoxin users). The median exposure for digoxin was 480 DDDs (interquartile range 100-1400 DDDs). During a median follow-up of 7.5 years after diagnosis, 617 men (48 digoxin users) died of prostate cancer. We collected information on antiarrhythmic drug purchases from the national prescription database. Both prediagnostic and postdiagnostic drug usages were analysed using the Cox regression method.

RESULTS

No association was found for prostate cancer death with digoxin usage before (HR 1.00, 95% CI 0.56-1.80) or after (HR 0.81, 95% CI 0.43-1.51) prostate cancer diagnosis. The results were also comparable for sotalol and antiarrhythmic drugs in general. Among men not receiving hormonal therapy, prediagnostic digoxin usage was associated with prolonged prostate cancer survival (HR 0.20, 95% CI 0.05-0.86).

CONCLUSIONS

No general protective effects against prostate cancer were observed for digoxin or sotalol usage.

β-Adrenergic modulation of cancer cell proliferation: available evidence and clinical perspectives

PURPOSE

In this review, we aimed to present and discuss the available preclinical and epidemiological evidences regarding the modulation of cancer cell proliferation by β-adrenoceptors (β-AR), with a specific focus on the putative effects of β-blockers according to their pharmacological properties.

METHODS

A comprehensive review of the published literature was conducted, and the evidences concerning the involvement of β-AR in cancer as well as the possible role of β-blockers were selected and discussed.

RESULTS

The majority of reviewed studies show that: (1) All the cancer types express both β1- and β2-AR, with the exception of neuroblastoma only seeming to express β2-AR; (2) adrenergic agonists are able to increase proliferation of several types of cancers; (3) the proliferative effect seems to be mediated by both β1- and β2-AR; (4) binding to β-AR results in a cAMP transient flux which activates two major downstream effector systems: protein kinase A and EPAC and (5) β-blockers might be putative adjuvants for cancer treatment.

CONCLUSIONS

Overall, the reviewed studies show strong evidences that β-AR activation, through several intracellular mechanisms, modulate tumor cell proliferation suggesting β-blockers can be a feasible therapeutic approach to antagonize β-adrenergic response or have a protective effect per se. This review highlight the need for intensifying the research not only on the molecular mechanisms underlying the β-adrenergic influence in cancer, but also on the implications of biased agonism of β-blockers as potential antitumor agents.

Obesity-induced p53 activation in insulin-dependent and independent tissues is inhibited by beta-adrenergic agonist in diet-induced obese rats

AIMS

The purpose of this study was to assay the role of beta-adrenergic receptor signaling in the regulation of obesity-induced p53 in high fat feeding obese rats.

MAIN METHODS

The role of beta-adrenergic receptor/cyclic AMP in the regulation of p53 and its downstream mediators was evaluated by western blot and real-time quantitative RT-PCR among diet induced rats.

KEY FINDINGS

Beta-adrenergic receptor agonist, isoproterenol, and an adenylate cyclase activator, forskolin, at a single dose significantly reduced insulin resistance consistent with a decrease in total and phospho-p53 levels in insulin and non-insulin metabolic target tissues. The decrease of p53 signaling was consistent with the elevation of AKT and subsequent activation. Obese rats exposed to fasting also exhibited improvement in insulin action despite a slight effect on p53 level.

SIGNIFICANCE

Results of the present study obviously showed that beta-adrenergic receptor agonist/cAMP prevented obesity-induced p53 activation. Although this effect in metabolic insulin target tissues tempted us to consider them as insulin sensitizers in obesity-related diabetes, p53 inhibition in non-insulin target tissues warned about the impairment of anti-cancer mechanisms in obese subjects.

Aspirin and atenolol enhance metformin activity against breast cancer by targeting both neoplastic and microenvironment cells

Metformin can induce breast cancer (BC) cell apoptosis and reduce BC local and metastatic growth in preclinical models. Since Metformin is frequently used along with Aspirin or beta-blockers, we investigated the effect of Metformin, Aspirin and the beta-blocker Atenolol in several BC models. In vitro, Aspirin synergized with Metformin in inducing apoptosis of triple negative and endocrine-sensitive BC cells, and in activating AMPK in BC and in white adipose tissue (WAT) progenitors known to cooperate to BC progression. Both Aspirin and Atenolol added to the inhibitory effect of Metformin against complex I of the respiratory chain. In both immune-deficient and immune-competent preclinical models, Atenolol increased Metformin activity against angiogenesis, local and metastatic growth of HER2+ and triple negative BC. Aspirin increased the activity of Metformin only in immune-competent HER2+ BC models. Both Aspirin and Atenolol, when added to Metformin, significantly reduced the endothelial cell component of tumor vessels, whereas pericytes were reduced by the addition of Atenolol but not by the addition of Aspirin. Our data indicate that the addition of Aspirin or of Atenolol to Metformin might be beneficial for BC control, and that this activity is likely due to effects on both BC and microenvironment cells.

Prostate cancer risk among users of digoxin and other antiarrhythmic drugs in the Finnish Prostate Cancer Screening Trial

PURPOSE

Long-term usage of the antiarrhythmic drug digoxin has been connected to lowered risk of prostate cancer. A recent study has suggested that beta-blockers might also have similar risk-decreasing effects. We evaluated the association between use of digoxin, beta-blocker sotalol, and other antiarrhythmic drugs and prostate cancer risk in a retrospective cohort study.

METHODS

Our study population consisted of men in the Finnish Prostate Cancer Screening Trial during 1996-2012 (n = 78,615). During median follow-up of 12 years, 6,639 prostate cancer cases were diagnosed. The national prescription database was the source of the information of antiarrhythmic drug purchases. Data were analyzed using Cox regression method with medication use as a time-dependent variable.

RESULTS

No association was found for overall prostate cancer risk with antiarrhythmic drug use (HR 1.05 95% CI 0.94-1.18). Neither sotalol (HR 0.97 95% CI 0.76-1.24) nor digoxin (HR 1.01 95% CI 0.87-1.16) users had a decreased risk of prostate cancer. Similar results were obtained for high-grade (Gleason 7-10) and metastatic prostate cancer. Nevertheless, the risk estimates for Gleason 7-10 prostate cancer tended to decrease by duration of digoxin use (p for trend = 0.052), suggesting that the drug may reduce the risk in long-term usage (HR 0.71, 95% CI 0.49-1.03). In analysis stratified by screening trial arm, the protective association against Gleason 7-10 disease was observed only in the screening arm (HR 0.31, 95% CI 0.12-0.84 for men who had used digoxin for 5 years or longer).

CONCLUSION

Digoxin or other antiarrhythmic drugs are not associated with any clear decrease in prostate cancer risk. However, digoxin might have a benefit in long-term use by reducing risk of high-grade disease. Further research will be needed to evaluate possible effects on prostate cancer survival.

β-Blockers Reduce Breast Cancer Recurrence and Breast Cancer Death: A Meta-Analysis

The normal physiologic stress mechanism, mediated by the sympathetic nervous system, causes a release of the neurotransmitters epinephrine and norepinephrine. Preclinical data have demonstrated an effect on tumor progression and metastasis via the sympathetic nervous system mediated primarily through the β-adrenergic receptor (β-AR) pathway. In vitro data have shown an increase in tumor growth, migration, tumor angiogenesis, and metastatic spread in breast cancer through activation of the β-AR. Retrospective cohort studies on the clinical outcomes of β-blockers in breast cancer outcomes showed no clear consensus. The purpose of this study was to perform a systematic review and meta-analysis of the effect of β-blockers on breast cancer outcomes. A systematic review was performed using the Cochrane library and PubMed. Publications between the dates of January 2010 and December 2013 were identified. Available hazard ratios (HRs) were extracted for breast cancer recurrence, breast cancer death, and all-cause mortality and pooled using a random effects meta-analysis. A total of 7 studies contained results for at least 1 of the outcomes of breast cancer recurrence, breast cancer death, or all-cause mortality in breast cancer patients receiving β-blockers. In the 5 studies that contained results for breast cancer recurrence, there was no statistically significant risk reduction (HR, 0.67; 95% confidence interval [CI], 0.39-1.13). Breast cancer death results were contained in 4 studies, which also suggested a significant reduction in risk (HR, 0.50; 95% CI, 0.32-0.80). Among the 4 studies that reported all-cause mortality, there was no significant effect of β-blockers on risk (HR, 1.02; 95% CI, 0.75-1.37). Results of this systematic review and meta-analysis suggest that the use of β-blockers significantly reduced risk of breast cancer death among women with breast cancer.

Propranolol Reduces Cancer Risk: A Population-Based Cohort Study

β-Blockers have been reported to exhibit potential anticancer effects in cancer cell lines and animal models. However, clinical studies have yielded inconsistent results regarding cancer outcomes and cancer risk when β-blockers were used. This study investigated the association between propranolol and cancer risk.Between January 1, 2000 and December 31, 2011, a patient cohort was extracted from the Longitudinal Health Insurance Database 2000, a subset of the Taiwan National Health Insurance Research Database. A propranolol cohort (propranolol usage >6 months) and nonpropranolol cohort were matched using a propensity score. Cox proportional hazard models were used to estimate the hazard ratio (HR) and 95% confidence intervals (CIs) of cancer associated with propranolol treatment.The study sample comprised 24,238 patients. After a 12-year follow-up period, the cumulative incidence for developing cancer was low in the propranolol cohort (HR: 0.75; 95% CI: 0.67-0.85; P < 0.001). Patients with propranolol treatment exhibited significantly lower risks of cancers in head and neck (HR: 0.58; 95% CI: 0.35-0.95), esophagus (HR: 0.35; 95% CI: 0.13-0.96), stomach (HR: 0.54; 95% CI: 0.30-0.98), colon (HR: 0.68; 95% CI: 0.49-0.93), and prostate cancers (HR: 0.52; 95% CI: 0.33-0.83). The protective effect of propranolol for head and neck, stomach, colon, and prostate cancers was most substantial when exposure duration exceeded 1000 days.This study supports the proposition that propranolol can reduce the risk of head and neck, esophagus, stomach, colon, and prostate cancers. Further prospective study is necessary to confirm these findings.

Delayed-onset of multiple cutaneous infantile hemangiomas due to propranolol: a case report

Infantile hemangiomas are the most common vascular tumors in childhood. In view of its proven effectiveness in such cases, propranolol is the drug of choice. We present the case of a male infant who started treatment with propranolol shortly after birth due to heart disease. After 7 months, when the patient had suffered various respiratory exacerbations, this treatment was suspended. One week later, multiple skin lesions (ie, multifocal infantile hemangiomas) began to appear, with no extracutaneous involvement. It was decided to resume treatment with propranolol, although at lower doses than before, and the skin lesions improved rapidly, with some disappearing completely. Treatment was definitively withdrawn at age 16 months, with only slight recurrence of the lesions. The case described is of multifocal infantile hemangiomas without extracutaneous involvement appearing beyond the neonatal period after treatment with propranolol beginning in the first days of life. The details of the case support the hypothesis that this drug is not only therapeutic but also plays a prophylactic role against infantile hemangiomas. In turn, this supports the recent proposal that this drug may be useful in preventing the growth and spread of tumors with high angiogenic potential. It is postulated that the inhibition of β-adrenergic receptors is associated with multiple intracellular processes related to the progression and metastasis of different tumors.

Infantile hemangiomas, retinopathy of prematurity and cancer: a common pathogenetic role of the β-adrenergic system

The serendipitous demonstration that the nonselective β-adrenergic receptor (β-AR) antagonist propranolol promotes the regression of infantile hemangiomas (IHs) aroused interest around the involvement of the β-adrenergic system in angiogenic processes. The efficacy of propranolol was related to the β2-AR blockade and the consequent inhibition of the production of vascular endothelial growth factor (VEGF), suggesting the hypothesis that propranolol could also be effective in treating retinopathy of prematurity (ROP), a retinal pathology characterized by VEGF-induced neoangiogenesis. Consequent to the encouraging animal studies, a pilot clinical trial showed that oral propranolol protects newborns from ROP progression, even though this treatment is not sufficiently safe. Further, animal studies clarified the role of β3-ARs in the development of ROP and, together with several preclinical studies demonstrating the key role of the β-adrenergic system in tumor progression, vascularization, and metastasis, prompted us to also investigate the participation of β3-ARs in tumor growth. The aim of this review is to gather the recent findings on the role of the β-adrenergic system in IHs, ROP, and cancer, highlighting the fact that these different pathologies, triggered by different pathogenic noxae, share common pathogenic mechanisms characterized by the presence of hypoxia-induced angiogenesis, which may be contrasted by targeting the β-adrenergic system. The mechanisms characterizing the pathogenesis of IHs, ROP, and cancer may also be active during the fetal-neonatal development, and a great contribution to the knowledge on the role of β-ARs in diseases characterized by chronic hypoxia may come from research focusing on the fetal and neonatal period.

A role for cAMP-driven transactivation of EGFR in cancer aggressiveness - therapeutic implications

In many common cancers, production of cAMP boosts cancer proliferation, survival, and aggressiveness, reflecting the fact that, through mechanisms that require further clarification, cAMP can promote tyrosine phosphorylation, notably transactivation of the epidermal growth factor receptor (EGFR). Hormones which activate adenylate cyclase in many cancers include PGE2 - often produced by cox-2 activity within tumors - and adrenergic hormones, acting on beta2 receptors. NSAID cyclooxygenase inhibitors, including low-dose aspirin, clearly reduce risk for many adenocarcinomas, but the impact of cox-2 inhibitors in clinical cancer therapy remains somewhat equivocal. There is increasing evidence that increased sympathetic drive, often reflecting psychic stress or tobacco usage, increases risk for, and promotes the aggressiveness of, many cancers. The non-specific beta antagonist propranolol shows cancer-retardant activity in pre-clinical rodent studies, especially in stressed animals, and a limited amount of epidemiology concludes that concurrent propranolol usage is associated with superior prognosis in breast cancer, ovarian cancer, and melanoma. Epidemiology correlating increased resting heart rate with increased total cancer mortality can be interpreted as compelling evidence that increased sympathetic drive encourages the onset and progression of common cancers. Conversely, hormones which inhibit adenylate cyclase activity in cancers may have potential for cancer control; GABA, which can be administered as a well-tolerated nutraceutical, has potential in this regard. Combination regimens intended to down-regulate cancer cAMP levels, perhaps used in conjunction with EGFR inhibitors, may have considerable potential for suppressing the contribution of cAMP/EGFR to cancer aggressiveness. This model also predicts that certain other hormones which activate adenylate cylase in various tissue may play a yet-unsuspected role in cancer induction and spread.