Use of blood-pressure-lowering medication and risk of prostate cancer in the Cancer Prevention Study II Nutrition Cohort

Role of antihypertensive medicines in prostate cancer: a systematic review

BACKGROUND

Hypertension is associated with the risk of prostate cancer (PCa) and its progression, however, it remains unclear whether antihypertensive medicines alter PCa risk or prognosis. This systematic review evaluated the role of calcium channel blockers (CCBs) and renin-angiotensin system (RAS) inhibitors in the risk and prognosis of PCa. This review was performed in line with PRISMA 2020 guidelines.

METHODS

Eligible studies comprised peer-reviewed observational studies which reported the role of CCBs and RAS inhibitors in PCa, had accessible full texts, and were written in English. Using a combination of keywords, 5 electronic bibliographic databases which included Web of Science, EMBASE, PubMed, Google Scholar and Scopus were searched.

RESULTS

A total of 1,346 studies were retrieved and 18 met the inclusion criteria. Thirteen studies reported reduced or no associated risk, improved prognosis, and survival with the use of RAS inhibitors. Studies on CCBs showed evidence of associated risk of PCa. Data extraction from retrieved studies focused on included study characteristics, setting, authors, year, outcomes of interest, and risk ratios. The quality assessment of included studies by the National Heart, Lung, and Blood Institute study assessment tools, showed that all studies had good quality.

CONCLUSIONS

The use of RAS inhibitors was mostly associated with lower risks or improved prognosis of PCa. CCBs may also be associated with risks of PCa. This suggests that high-risk patients managed with CCBs should be actively monitored for PCa. However, there is need for further evidence from large-scale prospective, controlled cohort studies to determine any influence of CCBs on PCa.

Cancer and Cardiovascular Disease: The Conjoined Twins

Cancer and cardiovascular disease are the two most common causes of death worldwide. As the fields of cardiovascular medicine and oncology continue to expand, the area of overlap is becoming more prominent demanding dedicated attention and individualized patient care. We have come to realize that both fields are inextricably intertwined in several aspects, so much so that the mere presence of one, with its resultant downstream implications, has an impact on the other. Nonetheless, cardiovascular disease and cancer are generally approached independently. The focus that is granted to the predominant pathological entity (either cardiovascular disease or cancer), does not allow for optimal medical care for the other. As a result, ample opportunities for improvement in overall health care are being overlooked. Herein, we hope to shed light on the interconnected relationship between cardiovascular disease and cancer and uncover some of the unintentionally neglected intricacies of common cardiovascular therapeutics from an oncologic standpoint.

The Risk for Prostate Cancer With Calcium Channel Blockers: A Systematic Review, Meta-Analysis, and Meta-Regression

BACKGROUND

For decades, conflicting results were published regarding the increased risk of Prostate cancer (PCa) among calcium channel blocker (CCB) users.

OBJECTIVE

We aimed to evaluate the association between PCa and CCB exposure and assess moderating factors.

METHODS

We performed a systematic literature search in PubMed, Embase, and Cochrane databases for observational and randomized studies published until November 2020 with no language limitations, including data on the risk for PCa in CCB users compared with non-CCB users. We applied a random-effects model meta-analysis to pool results. In addition, we investigated potential moderating factors, such as CCB type, study type, participants' age, and duration of exposure, using meta-regression methods.

RESULTS

In our primary analysis, we included 18 studies. A statistically significant 5% increase in the risk for PCa was observed among CCB users (risk ratio [RR] = 1.05; 95% confidence interval [CI]: 1.01-1.10), with no significant association between the duration of exposure to CCBs and the risk for PCa (RR = 1.08; 95% CI: 0.98-1.19 for exposure for < 5years and RR = 1.01; 95% CI: 0.9-1.14 for exposure ≥ 5 years). The association remained statistically significant for the subgroup of dihydropyridines (RR = 1.13; 95% CI: 1.05-1.22). In addition, the association was not influenced by participants' age.

CONCLUSION AND RELEVANCE

CCBs are an important modality in treating hypertension. The 5% increased risk observed in the current meta-analysis could be influenced by residual confounding factors and should not affect hypertension treatment guidelines until more studies provide additional clinical information.

β2-adrenoreceptor Signaling Increases Therapy Resistance in Prostate Cancer by Upregulating MCL1

There is accumulating evidence that continuous activation of the sympathetic nervous system due to psychosocial stress increases resistance to therapy and accelerates tumor growth via β2-adrenoreceptor signaling (ADRB2). However, the effector mechanisms appear to be specific to tumor type. Here we show that activation of ADRB2 by epinephrine, increased in response to immobilization stress, delays the loss of MCL1 apoptosis regulator (MCL1) protein expression induced by cytotoxic drugs in prostate cancer cells; and thus, increases resistance of prostate cancer xenografts to cytotoxic therapies. The effect of epinephrine on MCL1 protein depended on protein kinase A (PKA) activity, but was independent from androgen receptor expression. Furthermore, elevated blood epinephrine levels correlated positively with an increased MCL1 protein expression in human prostate biopsies. In summary, we demonstrate that stress triggers an androgen-independent antiapoptotic signaling via the ADRB2/PKA/MCL1 pathway in prostate cancer cells. IMPLICATIONS: Presented results justify clinical studies of ADRB2 blockers as therapeutics and of MCL1 protein expression as potential biomarker predicting efficacy of apoptosis-targeting drugs in prostate cancer.

Association Between the Overall Risk of Prostate Cancer and Use of Calcium Channel Blockers: A Systematic Review and Meta-analysis

PURPOSE

Although calcium channel blockers (CCBs) are now commonly prescribed to treat hypertension as a first-line drug therapy, their impact on prostate cancer (PCa) is unclear. This systematic review and meta-analysis was conducted to determine the association between CCB use and the overall risk of PCa.

METHODS

PubMed, EMBASE, and Cochrane were searched up to December 26, 2019, stratified according to statistical method of outcome [odd ratios (ORs), relative ratios (RRs), hazard ratios (HRs)] and cumulative duration of CCB use. The quality assessment of included studies was evaluated by using the Newcastle-Ottawa Scale. Fixed effects models were used to study the association between CCB use and the risk of PCa. Between-study heterogeneity was quantified by using Cochran's Q-statistic and I² statistics. Sensitivity analysis was performed by excluding the studies one by one, and publication bias was analyzed by using funnel plots.

FINDINGS

Nineteen studies with 1,418,407 patients were identified for inclusion in the meta-analysis, which was based on the comparison of cohort studies, nested case-control studies, and case-control studies. Pooled estimates showed a RR of 1.08 (95% CI, 1.05-1.11; P < 0.00001) and a HR of 1.07 (95% CI, 1.02-1.13; P = 0.008) for association between CCB use and the risk of PCa. In addition, the results of subgroup analysis showed that CCB users of <5 years had an 8% increased overall risk of PCa (RR, 1.08; 95% CI, 1.04-1.12; P = 0.0001), and CCB users of 5-10 years had a 13% increased overall risk of PCa (RR, 1.13; 95% CI, 1.04-1.23; P = 0.003).

IMPLICATIONS

CCB use had a tendency to increase the overall risk of PCa, and cumulative duration of CCB use might also be positively correlated with the overall risk of PCa.

Calcium Permeable Channels in Cancer Hallmarks

Cancer, the second cause of death worldwide, is characterized by several common criteria, known as the “cancer hallmarks” such as unrestrained cell proliferation, cell death resistance, angiogenesis, invasion and metastasis. Calcium permeable channels are proteins present in external and internal biological membranes, diffusing Ca²⁺ ions down their electrochemical gradient. Numerous physiological functions are mediated by calcium channels, ranging from intracellular calcium homeostasis to sensory transduction. Consequently, calcium channels play important roles in human physiology and it is not a surprise the increasing number of evidences connecting calcium channels disorders with tumor cells growth, survival and migration. Multiple studies suggest that calcium signals are augmented in various cancer cell types, contributing to cancer hallmarks. This review focuses in the role of calcium permeable channels signaling in cancer with special attention to the mechanisms behind the remodeling of the calcium signals. Transient Receptor Potential (TRP) channels and Store Operated Channels (SOC) are the main extracellular Ca²⁺ source in the plasma membrane of non-excitable cells, while inositol trisphosphate receptors (IP₃R) are the main channels releasing Ca²⁺ from the endoplasmic reticulum (ER). Alterations in the function and/or expression of these calcium channels, as wells as, the calcium buffering by mitochondria affect intracellular calcium homeostasis and signaling, contributing to the transformation of normal cells into their tumor counterparts. Several compounds reported to counteract several cancer hallmarks also modulate the activity and/or the expression of these channels including non-steroidal anti-inflammatory drugs (NSAIDs) like sulindac and aspirin, and inhibitors of polyamine biosynthesis, like difluoromethylornithine (DFMO). The possible role of the calcium permeable channels targeted by these compounds in cancer and their action mechanism will be discussed also in the review.

Spironolactone use is associated with lower prostate cancer risk: a population-wide case-control study

BACKGROUND

Spironolactone, a cheap effective diuretic used to manage hypertension and heart failure, also has anti-androgenic effects through its non-selective binding to steroid receptors, and hence may affect prostate cancer (PCa) risk. This study investigated the association between spironolactone use and PCa risk. For comparison, we also examined associations with thiazide diuretics which do not have anti-androgenic properties.

METHODS

A matched case-control study was undertaken using population-wide data from the Prostate Cancer Data Base Sweden (PCBaSe). All PCa cases diagnosed from 2014 to 2016 were matched by birth year and county with PCa-free controls selected from the general population (1:5). Multivariable conditional logistic regression was used to examine associations between spironolactone use (dose and duration) and PCa risk, and similarly for thiazides.

RESULTS

Three percent of the 31,591 cases and 4% of the 156,802 controls had been prescribed spironolactone. Multivariable analyses indicated reduced risk of PCa among those ever exposed to spironolactone (odds ratio [OR] 0.83; 95% confidence interval [CI]: 0.76-0.89), with a stronger association for current users (OR: 0.77, 95% CI: 0.69-0.86) than past users (OR: 0.88; 95% CI: 0.79-0.97) and decreasing risk with increasing dose (p-trend < 0.001). No association was observed for thiazide exposure and PCa risk. Biases due to differences in prescribing patterns or frequency of PSA testing may have influenced these findings.

CONCLUSION

PCa risk was reduced among men exposed to the diuretic spironolactone. Further investigation of spironolactone's potential chemopreventive effects is warranted.

Calcium Channel Blocker Use and the Risk for Prostate Cancer: A Population-Based Nested Case-Control Study

INTRODUCTION

Calcium channels play a significant role in the regulation of cell proliferation and apoptosis. This study investigates associations between calcium channel blocker (CCB) use and the incidence of prostate cancer (PCa).

METHODS

A nested case-control study was conducted using the Clalit Health Services database. We formed a population-based cohort of patients who were prescribed their first antihypertensive agent between 2000 and 2014. For each newly diagnosed PCa case in the cohort, 10 controls were matched by age, calendar year of cohort entry, and duration of follow-up. Multivariate conditional logistic regression analyses were used to evaluate the odds ratios (ORs) of PCa among CCB users compared with users of other antihypertensive drugs.

RESULTS

We identified 4346 patients with newly diagnosed PCa during the median follow-up of 5.3 years. The exposure to CCBs was associated with a slight increase in risk for PCa (OR 1.10, 95% confidence interval [CI] 1.02-1.18) when compared with non-CCB antihypertensive drugs. In secondary analyses, evidence was found of a duration-response relationship, with the association for PCa increasing by 27% for every 10-year increment of CCB use (OR 1.27, 95% CI 1.04-1.56).

CONCLUSIONS

The results of this large population-based study indicate a modest but significant increase in the risk of PCa among CCB users, and the risk increases with duration of use.

ADRB2-Targeting Therapies for Prostate Cancer

There is accumulating evidence that β-2 adrenergic receptor (ADRB2) signaling contributes to the progression and therapy resistance of prostate cancer, whereas availability of clinically tested β-blocker propranolol makes this pathway especially attractive as potential therapeutic target. Yet even in tumors with active ADRB2 signaling propranolol may be ineffective. Inhibition of apoptosis is one of the major mechanisms by which activation of ADRB2 contributes to prostate cancer pathophysiology. The signaling network that controls apoptosis in prostate tumors is highly redundant, with several signaling pathways targeting a few critical apoptosis regulatory molecules. Therefore, a comprehensive analysis of ADRB2 signaling in the context of other signaling mechanisms is necessary to identify patients who will benefit from propranolol therapy. This review discusses how information on the antiapoptotic mechanisms activated by ADRB2 can guide clinical trials of ADRB2 antagonist propranolol as potential life-extending therapy for prostate cancer. To select patients for clinical trials of propranolol three classes of biomarkers are proposed. First, biomarkers of ADRB2/cAMP-dependent protein kinase (PKA) pathway activation; second, biomarkers that inform about activation of other signaling pathways unrelated to ADRB2; third, apoptosis regulatory molecules controlled by ADRB2 signaling and other survival signaling pathways.

Antihypertensive drugs use and the risk of prostate cancer: a meta-analysis of 21 observational studies

Background

Due to the lack of strong evidence to identify the relationship between antihypertensive drugs use and the risk of prostate cancer, it was needed to do a systematic review to go into the subject.

Methods

We systematically searched PubMed, Web of Science and Embase to identify studies published, through May 2015. Two evaluators independently reviewed and selected articles involving the subject. We used the Newcastle-Ottawa Scale (NOS) to assess the quality of the studies. All extracted results to evaluate the relationship between antihypertensive drugs usage and prostate cancer risk were pool-analysed using Stata 12.0 software.

Results

A total of 12 cohort and 9 case-control studies were ultimately included in our review. Most of the studies were evaluated to be of high quality. There was no significant relationship between angiotensin converting enzyme inhibitors (ACEI) usage and the risk of prostate cancer (RR 1.07, 95% CI 0.96–1.20), according to the total pool-analysed. Use of angiotensin receptor blocker (ARB) was not associated with the risk of prostate cancer (RR 1.09, 95% CI 0.97–1.21), while use of CCB may well increase prostate cancer risk based on the total pool-analysed (RR 1.08, 95% CI 1–1.16). Moreover, subgroup analysis suggested that use of CCB clearly increased prostate cancer risk (RR 1.10, 95% CI 1.04–1.16) in terms of case-control studies. There was also no significant relationship between use of diuretic (RR 1.09, 95% CI 0.95–1.25) or antiadrenergic agents (RR 1.22, 95% CI 0.76–1.96) and prostate cancer risk.

Conclusions

There is no significant relationship between the use of antihypertensive drugs (ACEI, ARB, beta-blockers and diuretics) and prostate cancer risk, but CCB may well increase prostate cancer risk, according to existing observational studies.

Electronic supplementary material

The online version of this article (10.1186/s12894-018-0318-7) contains supplementary material, which is available to authorized users.

Adrenergic blockers and the risk for common solid cancers: a case-control study

Laboratory studies have suggested that adrenergic blockers may inhibit the proliferation and migration of cancer cells, but epidemiological evidence of their effect on cancer incidence has proven inconsistent. We therefore conducted a case-control study using the Clinical Practice Research Datalink to assess the effect of adrenergic blockers on the incidence of prostate, lung, bowel and breast cancers. From among patients aged 18 years or older who contributed at least 2 years of prospectively gathered data between 1 January 1987 and 31 December 2012, we selected incident cases of relevant cancers and controls, frequency matched 10 : 1 by age. Logistic regression was used to adjust effect estimates for age, sex, smoking, alcohol use, and a number of potentially confounding comorbidities and coprescriptions. A total of 18 968 colorectal, 19 082 lung, 21 608 prostate and 29 109 breast cancers were identified. We found no evidence of a protective effect of adrenergic blockade in lung and prostate cancers and found a slightly increased risk for colorectal and breast cancers in users. This was largely explained by the effects of confounding in multivariate analyses, with final odds ratio estimates for lung, colorectal, breast and prostate cancers of 0.99 [95% confidence interval (0.96-1.04)], 1.14 (1.09-1.18), 1.10 (1.06-1.14), and 1.01 (0.98-1.05), respectively, for β-blocker exposure, and final odds ratio estimates for lung, colorectal and breast cancer of 1.03 (0.97-1.09), 1.13 (1.07-1.20), and 1.08 (1.00-1.17), respectively, for α-blocker exposure. We found no evidence to suggest that adrenergic blocker use prevents common cancers. Indeed, we found a slightly increased risk for colorectal and breast cancers, which may reflect residual confounding.

Midlife metabolic factors and prostate cancer risk in later life

Metabolic syndrome is associated with several cancers, but evidence for aggressive prostate cancer is sparse. We prospectively investigated the influence of metabolic syndrome and its components on risk of total prostate cancer and measures of aggressive disease in a cohort of Icelandic men. Men in the Reykjavik Study (n = 9,097, enrolled 1967-1987) were followed for incident (n = 1,084 total; n = 378 advanced; n = 148 high-grade) and fatal (n = 340) prostate cancer until 2014. Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for (1) measured metabolic factors at cohort entry (body mass index (BMI), blood pressure, triglycerides, fasting blood glucose) and (2) a metabolic syndrome score (range 0-4) combining the risk factors: BMI ≥30 kg/m² ; systolic blood pressure (SBP) ≥130 or diastolic blood pressure (DBP) ≥85 mm Hg or taking antihypertensives; triglycerides ≥150 mg/dl; fasting blood glucose ≥100 mg/dl or self-reported type 2 diabetes. Hypertension and type 2 diabetes were associated with a higher risk of total, advanced, high-grade, and fatal prostate cancer, independent of BMI. Neither BMI nor triglycerides were associated with prostate cancer risk. Higher metabolic syndrome score (3-4 vs 0) was associated with a higher risk of fatal prostate cancer (HR 1.55; 95% CI: 0.89, 2.69; p trend = 0.08), although this finding was not statistically significant. Our findings suggest a positive association between midlife hypertension and diabetes and risk of total and aggressive prostate cancer. Further, metabolic syndrome as a combination of factors was associated with an increased risk of fatal prostate cancer.

Calcium Channel Blocker Use and Risk of Prostate Cancer by TMPRSS2:ERG Gene Fusion Status

BACKGROUND

Calcium channel blockers (CCBs) may affect prostate cancer (PCa) growth by various mechanisms including those related to androgens. The fusion of the androgen-regulated gene TMPRSS2 and the oncogene ERG (TMPRSS2:ERG or T2E) is common in PCa, and prostate tumors that harbor the gene fusion are believed to represent a distinct disease subtype. We studied the association of CCB use with the risk of PCa, and molecular subtypes of PCa defined by T2E status.

METHODS

Participants were residents of King County, Washington, recruited for population-based case-control studies (1993-1996 or 2002-2005). Tumor T2E status was determined by fluorescence in situ hybridization using tumor tissue specimens from radical prostatectomy. Detailed information on use of CCBs and other variables was obtained through in-person interviews. Binomial and polytomous logistic regression were used to generate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The study included 1,747 PCa patients and 1,635 age-matched controls. A subset of 563 patients treated with radical prostatectomy had T2E status determined, of which 295 were T2E positive (52%). Use of CCBs (ever vs. never) was not associated with overall PCa risk. However, among European-American men, users had a reduced risk of higher-grade PCa (Gleason scores ≥7: adjusted OR = 0.64; 95% CI: 0.44-0.95). Further, use of CCBs was associated with a reduced risk of T2E positive PCa (adjusted OR = 0.38; 95% CI: 0.19-0.78), but was not associated with T2E negative PCa.

CONCLUSIONS

This study found suggestive evidence that use of CCBs is associated with reduced relative risks for higher Gleason score and T2E positive PCa. Future studies of PCa etiology should consider etiologic heterogeneity as PCa subtypes may develop through different causal pathways. Prostate 77:282-290, 2017. © 2016 Wiley Periodicals, Inc.

Is angiotensin-converting enzyme inhibitors/angiotensin receptor blockers therapy protective against prostate cancer?

Emerging evidence suggests that renin-angiotensin system (RAS) may act as a molecular and therapeutic target for treating site-specific cancers, including prostate cancer. However, previous observational studies regarding the association between RAS inhibitors and prostate cancer risk have reported inconsistent results. We examined this association by performing a systematic review and meta-analysis. A total of 20,267 patients from nine cohort studies were enrolled. Compared with non-users of RAS inhibitors, individuals using RAS inhibitors had a reduced risk of prostate cancer (RR 0.92, 95 % CI 0.87-0.98), without statistically significant heterogeneity among studies (P = 0.118 for heterogeneity, I2 = 37.6 %). In addition, when subgroup analyses by study quality and number of cases, more statistically significant associations were observed in studies of high quality (RR 0.93, 95 % CI 0.88-0.97) and large sample size (RR 0.94, 95 % CI 0.91-0.98). There was no evidence of significant publication bias with Begg's test (P = 0.602) or with Egger's test (P = 0.350). Overall, this study indicates that use of RAS inhibitors may be associated with a decreased risk of prostate cancer. Large-scale well designed studies are needed to further explore this association.

CaV channels and cancer: canonical functions indicate benefits of repurposed drugs as cancer therapeutics

The importance of ion channels in the hallmarks of many cancers is increasingly recognised. This article reviews current knowledge of the expression of members of the voltage-gated calcium channel family (Ca_V) in cancer at the gene and protein level and discusses their potential functional roles. The ten members of the Ca_V channel family are classified according to expression of their pore-forming α-subunit; moreover, co-expression of accessory α2δ, β and γ confers a spectrum of biophysical characteristics including voltage dependence of activation and inactivation, current amplitude and activation/inactivation kinetics. Ca_V channels have traditionally been studied in excitable cells including neurones, smooth muscle, skeletal muscle and cardiac cells, and drugs targeting the channels are used in the treatment of hypertension and epilepsy. There is emerging evidence that several Ca_V channels are differentially expressed in cancer cells compared to their normal counterparts. Interestingly, a number of Ca_V channels also have non-canonical functions and are involved in transcriptional regulation of the expression of other proteins including potassium channels. Pharmacological studies show that Ca_V canonical function contributes to the fundamental biology of proliferation, cell-cycle progression and apoptosis. This raises the intriguing possibility that calcium channel blockers, approved for the treatment of other conditions, could be repurposed to treat particular cancers. Further research will reveal the full extent of both the canonical and non-canonical functions of Ca_V channels in cancer and whether calcium channel blockers are beneficial in cancer treatment.

The Incidence and Risk of Biochemical Recurrence Following Radical Radiotherapy for Prostate Cancer in Men on Angiotensin-Converting Enzyme Inhibitors (ACEIs) or Angiotensin Receptor Blockers (ARBs)

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) are linked to prostate cancer, but their effect on biochemical recurrence (BR) remains unknown. Our aims were to investigate the incidence and risk of BR in men on ACEIs/ARBs after radical radiotherapy with adjuvant∖neoadjuvant hormone treatment.

MATERIAL AND METHODS

A propensity score analysis of 558 men was conducted. Men were stratified into 3 groups: hypertensive men on ACEIs/ARBs (as a study group), non-hypertensive men not on ACEIs/ARBs, and hypertensive men not on ACEIs/ARBs (both as a control group). The multivariate analysis of variance, chi-square, Kruskal-Wallis, analysis of variance, risk ratio, confidence interval, Kaplan-Meier plots, and log-rank tests were used.

RESULTS

The mean age and follow-up were 68.51 and 3.33 years, respectively. There was a statistically significant difference in the prevalence of BR among the treatment groups (P < .001). The incidence of BR was significantly lower in hypertensive men taking ACEIs/ARBs than in non-hypertensive men not taking ACEIs/ARBs (P < .001) or in hypertensive men not taking ACEIs/ARBs (P < .009). The incidence of BR was significantly lower in hypertensive men not taking ACEIs/ARBs than in non-hypertensive men not taking ACEIs/ARBs (P < .013). The risk ratio (RR) of BR in the group of hypertensive men taking ACEIs/ARBs was significantly lower than in the group of non-hypertensive men not taking ACEIs/ARBs (RR, 0.74; 95% CI, 0.64-0.86; P < .001) and in the group of hypertensive men not taking ACEIs/ARBs (RR, 0.78; 95% CI, 0.67-0.91; P < .001). The time-to-event analysis revealed that the group of hypertensive men taking ACEIs/ARBs was significantly different compared with the control groups (P < .031).

CONCLUSION

Men who were taking ACEIs/ARBs had significantly lower incidence of BR after radical radiotherapy with hormone treatment. The intake of ACEIs/ARBs was associated with reduced risk of BR.

β-Adrenergic system, a backstage manipulator regulating tumour progression and drug target in cancer therapy

β-Adrenoceptors are broadly distributed in various tissues of the body. Stress hormones regulate a panel of important physiological functions and disease states including cancer. Nicotine and its derivatives could stimulate the release of stress hormones from cancer cells, leading to the promotion of cancer development. β-Blockers have been widely used to control hypertension for decades. Recently, these agents could have significant implications in cancer therapy through blockade of adrenoceptors in tumour tissues. In this review, we summarize recent advancements about the influence of stress hormones, nicotine and β-adrenoceptors on cancer cell proliferation, apoptosis, invasion and metastasis, and also tumour vasculature normalization. Relevant signal pathways and potential value of β-blockers in the treatment of cancer are also discussed in this review.

The association between calcium channel blocker use and prostate cancer outcome

BACKGROUND

Epidemiological studies indicate that calcium channel blocker (CCB) use is inversely related to prostate cancer (PCa) incidence. The association between CCB use and PCa aggressiveness at the time of radical prostatectomy (RP) and outcome after RP was examined.

METHODS

Medication use, PCa aggressiveness and post-RP outcome were retrieved from a prospectively populated database that contains clinical and outcome for RP patients at Roswell Park Cancer Institute (RPCI) from 1993 to 2010. The database was queried for anti-hypertensive medication use at diagnosis for patients with ≥1 year follow-up. Recurrence was defined using NCCN guidelines. Chi-Square tests assessed the relationship between CCB use and PCa aggressiveness. Cox regression models compared the distribution of progression-free survival (PFS) and overall survival (OS) with adjustment for covariates. Results for association between CCB usage and PCa aggressiveness were validated using data from the population-based North Carolina-Louisiana Prostate Cancer Project (PCaP).

RESULTS

48%, 37%, and 15% of RPCI's RP patients (n = 875) had low, intermediate, and high aggressive PCa, respectively. 104 (11%) had a history of CCB use. Patients taking CCBs were more likely to be older, have a higher BMI and use additional anti-hypertensive medications. Diagnostic PSA levels, PCa aggressiveness, and margin status were similar for CCB users and non-users. PFS and OS did not differ between the two groups. Tumor aggressiveness was associated with PFS. CCB use in the PCaP study population was not associated with PCa aggressiveness.

CONCLUSIONS

CCB use is not associated with PCa aggressiveness at diagnosis, PFS or OS.

Use of β-blockers is associated with prostate cancer-specific survival in prostate cancer patients on androgen deprivation therapy

BACKGROUND

Experimental evidence suggests a role for the β(2) -adrenergic receptor pathway in prostate cancer (PCa). We have investigated the association of β-blocker use with PCa incidence and survival in a Norwegian cohort.

METHODS

Data from the Oslo II study in 2000 (n = 6515) were linked with information from the Cancer Registry of Norway and Statistics Norway. PCa risk and overall- and PCa-specific mortality were analyzed using uni- and multi-variable Cox- and competing risk regression models.

RESULTS

At baseline, 776 men (11.9%) reported using a β-blocker. 212 men (3.3%) were diagnosed with PCa before the survey, leaving 6,303 eligible for incidence analysis. During a median follow-up of 122 months, 448 (7.1%) men were diagnosed with PCa. β-blocker use was not associated with PCa risk [hazard ratio (HR): 1.05, 95% CI: 0.79-1.40]. For all patients (n = 655; including med diagnosed before the survey), β-blocker use was not associated with PCa-specific mortality (HR: 0.55, 95% CI 0.24-1.26, P = 0.16). However, in the subgroup of men planned to receive androgen deprivation therapy (ADT), as reported to the Cancer Registry (n = 263), β-blocker use was associated with reduced PCa-specific mortality (HR: 0.14, 95% CI 0.02-0.85, P = 0.032). No effect on overall mortality was seen (HR, all patients: 0.88, 95% CI 0.56-1.38, P = 0.57). β-blocker use did not appear to affect PSA level, Gleason score, or T-stage at diagnosis; however, these variables were missing for many cases.

CONCLUSIONS

Our findings demonstrate a possible benefit of β-blocker use for men treated with ADT, suggesting the need for investigation in larger cohorts.

β-blockers: a novel class of antitumor agents

β-adrenergic signaling modulates key signaling pathways that are important for tumor-promoting processes, and numerous mechanisms of action have been elucidated. Preclinical studies have demonstrated that β-adrenergic antagonists, or β-blockers, can block multiple fundamental biologic processes underlying the progression and metastasis of tumors, including the inhibition of cell proliferation, migration, invasion, resistance to programmed cell death, and tumor angiogenesis and metastasis. Human pharmacoepidemiologic studies suggest that β-blockers have a role in inhibiting cancer progression and metastasis in combination with standard therapies. Furthermore, a number of prospective studies have demonstrated that β-blockers are effective at halting infantile hemangioma growth. These findings shed light on the novel perspective of using β-blockers as a class of potential antitumor agents in clinical oncology.

Beta blockers, norepinephrine, and cancer: an epidemiological viewpoint

There is growing evidence that the neurotransmitter norepinephrine (NE) and its sister molecule epinephrine (EPI) (adrenaline) affect some types of cancer. Several recent epidemiological studies have shown that chronic use of beta blocking drugs (which antagonize NE/EPI receptors) results in lower recurrence, progression, or mortality of breast cancer and malignant melanoma. Preclinical studies have shown that manipulation of the levels or receptors of NE and EPI with drugs affects experimentally induced cancers. Psychological stress may play an etiological role in some cases of cancer (which has been shown epidemiologically), and this could be partly mediated by NE and EPI released by the sympathetic nervous system as part of the body’s “fight or flight” response. A less well-appreciated phenomenon is that the genetic tone of NE/EPI may play a role in cancer. NE and EPI may affect cancer by interacting with molecular pathways already implicated in abnormal cellular replication, such as the P38/MAPK pathway, or via oxidative stress. NE/EPI-based drugs other than beta blockers also may prevent or treat various types of cancer, as may cholinesterase inhibitors that inhibit the sympathetic nervous system, which could be tested epidemiologically.

Diltiazem enhances the apoptotic effects of proteasome inhibitors to induce prostate cancer cell death

Diltiazem is a calcium channel blocker used to treat cardiovascular ailments. In addition, reports suggest that diltiazem induces cell death, which could make it a drug of choice for the treatment of cancer associated with hypertension. The goal of this research was to determine whether diltiazem is capable of inducing apoptosis in prostate cancer cells, either alone or in combination with the proteasome inhibitors, lactacystin and bortezomib (Velcade). Bortezomib is approved for the treatment of multiple myeloma; unfortunately, it has side effects that limit its utility. Presumably these side effects could be decreased by reducing its dose in combination with another drug. We have previously shown that lactacystin induces apoptosis in LNCaP cells; here, we show that this effect was enhanced by diltiazem. Furthermore, in proteasome inhibitor-resistant DU145 cells, diltiazem alone did not induce apoptosis but decreased cytosolic calcium levels and induced mitochondrial fission; likewise, lactacystin did not induce apoptosis but up-regulated the proapoptotic protein Bik. However, increasing concentrations of diltiazem in combination with lactacystin or bortezomib induced apoptosis in a dose-dependent and synergistic manner. The combination of diltiazem and lactacystin also up-regulated the levels of Bik and released Bak from Bcl-xL, indicating the involvement of the Bcl2 family pathway in this apoptosis. In addition, the drug combination up-regulated GRP78, suggesting also the involvement of endoplasmic reticulum stress in the apoptotic response. Thus, our results demonstrate a potential therapeutic advantage of combining a frequently used calcium channel blocker with proteasome inhibitors in the treatment of prostate cancer.

Cardiovascular medications and risk of cancer

Cardiovascular disease and cancer are 2 of the leading causes of death globally. Certain cardiovascular medications have been linked to an increased risk for cancer. Although individual reviews of specific classes of cardiovascular medications have been published previously, a more complete review of several classes has not been performed. The aim of this review is to evaluate the associations of various cardiovascular agents with the risk for developing cancer and provide guidance for clinicians. A comprehensive search of published research was conducted using MEDLINE from 1994 to 2011. Three trials demonstrated an increased risk for cancer using angiotensin II receptor blockers. Additionally, risk for cancer was shown in a number of trials that included the use of angiotensin II receptor blockers in combination with angiotensin-converting enzyme inhibitors. Five trials suggested that diuretics increased the risk for specific cancers, especially in women and those who had been using diuretics for >4 years. Statins and ezetimibe, in contrast, did not show this increased risk. Prasugrel was shown to be associated with an increased risk for cancer in 1 study. It appears that the use of certain cardiovascular medications is associated with an increased risk for cancer. In conclusion, clinicians need to balance the risks and benefits of the use of these agents and provide the appropriate therapy on an individual basis.

The Metabolic Syndrome and Biochemical Recurrence following Radical Prostatectomy

Metabolic syndrome refers to a set of conditions that increases the risk of cardiovascular disease and has been associated with an increased risk of prostate cancer, particularly among African American men. This study aimed to estimate the association of metabolic syndrome with biochemical recurrence (BCR) in a racially diverse population. Among 383 radical prostatectomy patients, 67 patients had documented biochemical recurrence. Hypertension was significantly, positively associated with the rate of BCR (hazard ratio (HR) = 2.1; 95%  CI = 1.1, 3.8). There were distinct racial differences in the prevalence of individual metabolic syndrome components; however, the observed associations with BCR did not differ appreciably by race. We conclude that hypertension may contribute to a poorer prognosis in surgically treated prostate cancer patients. Our findings suggest that targeting components of the metabolic syndrome which are potentially modifiable through lifestyle interventions may be a viable strategy to reduce risk of BCR in prostate cancer.

Use of angiotensin-converting-enzyme inhibitors or angiotensin-receptor blockers and cancer risk: a meta-analysis of observational studies

BACKGROUND

Epidemiologic studies have reported inconsistent findings regarding the association between the use of angiotensin-converting-enzyme (ACE) inhibitors or angiotensin-receptor blockers and the risk of cancer. We performed a meta-analysis of observational studies to assess the association.

METHODS

We searched MEDLINE, EMBASE and the Cochrane Library to identify studies through January 2011. Two evaluators independently reviewed and selected articles of cohort and case-control studies on the basis of predetermined selection criteria.

RESULTS

Of 3970 screened articles, 12 cohort studies and 16 case-control studies were selected for analysis. We found no significant association between the use of ACE inhibitors or angiotensin-receptor blockers and the overall risk of cancer (relative risk [RR] 0.96, 95% confidence interval [CI] 0.90-1.03). We found a decreased risk of cancer associated with use of either medication when we restricted the analyses to cohort and nested case-control studies (RR 0.90, 95% CI 0.83-0.97) or to studies with long-term follow-up of more than five years (RR 0.89, 95% CI 0.83-0.96). In the subgroup meta-analyses by cancer site, a decreased risk was identified for esophageal cancer, whereas an increased risk was found for melanoma and kidney cancer.

INTERPRETATION

No significant association was found between the use of ACE inhibitors or angiotensin-receptor blockers and overall risk of cancer. A possible beneficial effect associated with use of either medication was suggested in sensitivity analyses, including those of studies with long-term follow-up. Large randomized controlled trials with long-term follow-up are needed to specifically test the effect of each of these medications on the risk of cancer.

Neurotransmitters, more than meets the eye--neurotransmitters and their perspectives in cancer development and therapy

The neurotransmitter/receptor system has been shown to modulate various aspects of tumor development including cell proliferation, angiogenesis, invasion, migration and metastasis. It has been found that tumor tissues can not only synthesize and release a wide range of neurotransmitters but also produce different biological effects via respective receptors. These tissues are also innervated by nerve fibers but the biological significance is unknown. Nevertheless neurotransmitters can produce either stimulatory or inhibitory effect in normal and tumor tissues. These effects are dependent on the types of tissues and the kinds of neurotransmitter as well as the subtypes of corresponding receptors being involved. These findings clearly extend the conventional role of neurotransmitters in nervous system to the actions in oncogenesis. In this regard, intervention or stimulation of these neuronal pathways in different cancer diseases would have significant clinical implications in cancer treatments. Here, we summarize the influences of various well-characterized neurotransmitters and their receptors on tumor growth and further discuss the respective possible strategies and perspectives for cancer therapy in the future.

Natriuretic peptide receptor a as a novel target for prostate cancer

BACKGROUND

The receptor for the cardiac hormone atrial natriuretic peptide (ANP), natriuretic peptide receptor A (NPRA), is expressed in cancer cells, and natriuretic peptides have been implicated in cancers. However, the direct role of NPRA signaling in prostate cancer remains unclear.

RESULTS

NPRA expression was examined by western blotting, RT-PCR and immunohistochemistry. NPRA was downregulated by transfection of siRNA, shRNA and NPRA inhibitor (iNPRA). Antitumor efficacy of iNPRA was tested in mice using a TRAMP-C1 xenograft. Here, we demonstrated that NPRA is abundantly expressed on tumorigenic mouse and human prostate cells, but not in nontumorigenic prostate epithelial cells. NPRA expression showed positive correlation with clinical staging in a human PCa tissue microarray. Down-regulation of NPRA by siNPRA or iNPRA induced apoptosis in PCa cells. The mechanism of iNPRA-induced anti-PCa effects was linked to NPRA-induced expression of macrophage migration inhibitory factor (MIF), a proinflammatory cytokine over-expressed in PCa and significantly reduced by siNPRA. Prostate tumor cells implanted in mice deficient in atrial natriuretic peptide receptor A (NPRA-KO) failed to grow, and treatment of TRAMP-C1 xenografts with iNPRA reduced tumor burden and MIF expression. Using the TRAMP spontaneous PCa model, we found that NPRA expression correlated with MIF expression during PCa progression.

CONCLUSIONS

Collectively, these results suggest that NPRA promotes PCa development in part by regulating MIF. Our findings also suggest that NPRA is a potential prognostic marker and a target for PCa therapy.

Blood pressure, body size and prostate cancer risk in the Swedish Construction Workers cohort

Data from prospective studies on blood pressure and prostate cancer risk are limited, and results are inconclusive. Baseline measurements of height, weight and blood pressure were available in 336,159 men in the Swedish Construction Workers cohort. During an average of 22.2 years of follow-up, 10,002 incident cases and 2,601 fatal cases of prostate cancer were identified in National registers. For 5,219 cases, tumor characteristics were available; 2,817 tumors were classified as nonaggressive and 2,402 as aggressive. Relative risks of disease were estimated from Cox regression models, using attained age as time-scale, and adjusting for birth year, smoking status and body mass index (BMI). Top compared to bottom quintile level of systolic or diastolic blood pressure was associated with a significant 15-20% decreased risk of incident prostate cancer (p for trend: systolic < 0.0001, diastolic = 0.3), but blood pressure was not significantly associated with risk of fatal prostate cancer. BMI was not associated with prostate cancer incidence, but was positively associated with fatal prostate cancer; men in the top quintile had a 30% increased risk (p for trend = 0.0004). The associations between blood pressure and BMI and nonaggressive tumors were similar to those of incident prostate cancer, and associations with aggressive tumors were similar to those of fatal prostate cancer. Data from our study suggest that hypertension is associated with a decreased risk of incident prostate cancer, but the explanation for this finding is unclear. Our study support a positive association between overweight and risk of fatal prostate cancer.

Sympathetic Neurotransmitters and Tumor Angiogenesis-Link between Stress and Cancer Progression

Recent evidence supports a longstanding hypothesis that chronic stress can influence tumor growth and progression. It has been shown that sympathetic neurotransmitters, such as catecholamines and neuropeptides, can affect both cancer cell growth and tumor vascularization. Depending on neurotransmitter and type of tumor, these effects can be both stimulatory and inhibitory. Norepinephrine (NE) and epinephrine (E) are potent stimulators of vascularization, acting both by inducing the release of angiogenic factors from tumor cells and directly on endothelial cell (EC) functions. As a result, activation of the adrenergic system increases growth of various types of tumors and has been shown to mediate stress-induced augmentation of tumor progression. Dopamine (DA), on the other hand, interferes with VEGF signaling in endothelial cells, blocks its angiogenic functions and inhibits tumor growth. Another sympathetic neurotransmitter coreleased with NE, neuropeptide Y (NPY), directly stimulates angiogenesis. However, proangiogenic actions of NPY can be altered by its direct effect on tumor cell proliferation and survival. In consequence, NPY can either stimulate or inhibit tumor growth, depending on tumor type. Hence, sympathetic neurotransmitters are powerful modulators of tumor growth and can become new targets in cancer therapy.

Blood pressure and risk of prostate cancer: Cohort Norway (CONOR)

BACKGROUND

Some studies suggest that raised blood pressure may increase prostate cancer risk. We investigated associations of blood pressure with prostate cancer within the CONOR collaborative cohorts of Norway.

METHODS

Between 1994 and 2003, 82,098 men from ten population-based cohorts in Norway completed standardised questionnaires and physical examinations, including resting blood pressure. The unique 11-digit identification number of Norwegian citizens allowed linkage with the Cancer Registry of Norway.

RESULTS

A total of 78,768 (96%) men who were cancer-free at baseline and average age of 50.3 years (standard deviation, SD: 15.2) were followed up for a mean of 9.15 years. 11.4% of these men used antihypertensive drugs at baseline. During follow-up (1994-2006), 1,974 incident prostate cancers were diagnosed. We found a 4% (95% confidence interval, CI = 0-9%) increased risk of prostate cancer per one SD (18.3 mmHg) increase in systolic blood pressure and similar findings for diastolic blood pressure (hazard ratio, HR: 1.05 per SD; 95% CI = 1.01-1.10). The association was stronger for advanced (HR: 1.16 per SD increase in systolic blood pressure; 95% CI = 1.05-1.27) compared with localised (1.01; 0.95-1.08) prostate cancer (p for heterogeneity in hazard ratios = 0.02).

CONCLUSIONS

Raised blood pressure was associated with an increased risk of prostate cancer, particularly advanced cancers at diagnosis. Understanding the mechanisms underlying these findings may provide biological insights into prostate carcinogenesis. Even if the association was causal, our data suggest that raised blood pressure would account for only 3% of prostate cancers, so the public health impact of this association may be limited.