Alpha 2 -adrenoceptor agonists trigger prolactin signaling in breast cancer cells

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

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

Trial watch: dexmedetomidine in cancer therapy

Dexmedetomidine (DEX) is a highly selective α2-adrenoceptor agonist that is widely used in intensive and anesthetic care for its sedative and anxiolytic properties. DEX has the capacity to alleviate inflammatory pain while limiting immunosuppressive glucocorticoid stress during major surgery, thus harboring therapeutic benefits for oncological procedures. Recently, the molecular mechanisms of DEX-mediated anticancer effects have been partially deciphered. Together with additional preclinical data, these mechanistic insights support the hypothesis that DEX-induced therapeutic benefits are mediated via the stimulation of adaptive anti-tumor immune responses. Similarly, published clinical trials including ancillary studies described an immunostimulatory role of DEX during the perioperative period of cancer surgery. The impact of DEX on long-term patient survival remains elusive. Nevertheless, DEX-mediated immunostimulation offers an interesting therapeutic option for onco-anesthesia. Our present review comprehensively summarizes data from preclinical and clinical studies as well as from ongoing trials with a distinct focus on the role of DEX in overcoming (tumor microenvironment (TME)-imposed) cancer therapy resistance. The objective of this update is to guide clinicians in their choice toward immunostimulatory onco-anesthetic agents that have the capacity to improve disease outcome.

β-Adrenoceptors in Cancer: Old Players and New Perspectives

Distress, or negative stress, is known to considerably increase the incidence of several diseases, including cancer. There is indeed evidence from pre-clinical models that distress causes a catecholaminergic overdrive that, mainly through the activation of β-adrenoceptors (β-ARs), results in cancer cell growth and cancer progression. In addition, clinical studies have evidenced a role of negative stress in cancer progression. Moreover, plenty of data demonstrates that β-blockers have positive effects in reducing the pro-tumorigenic activity of catecholamines, correlating with better outcomes in some type of cancers as evidenced by several clinical trials. Among β-ARs, β2-AR seems to be the main β-AR subtype involved in tumor development and progression. However, there are data indicating that also β1-AR and β3-AR may be involved in certain tumors. In this chapter, we will review current knowledge on the role of the three β-AR isoforms in carcinogenesis as well as in cancer growth and progression, with particular emphasis on recent studies that are opening new avenues in the use of β-ARs as therapeutic targets in treating tumors.

Tumour immune rejection triggered by activation of α2-adrenergic receptors

Immunotherapy based on immunecheckpoint blockade (ICB) using antibodies induces rejection of tumours and brings clinical benefit in patients with various cancer types¹. However, tumours often resist immune rejection. Ongoing efforts trying to increase tumour response rates are based on combinations of ICB with compounds that aim to reduce immunosuppression in the tumour microenvironment but usually have little effect when used as monotherapies^2,3. Here we show that agonists of α2-adrenergic receptors (α2-AR) have very strong anti-tumour activity when used as monotherapies in multiple immunocompetent tumour models, including ICB-resistant models, but not in immunodeficient models. We also observed marked effects in human tumour xenografts implanted in mice reconstituted with human lymphocytes. The anti-tumour effects of α2-AR agonists were reverted by α2-AR antagonists, and were absent in Adra2a-knockout (encoding α2a-AR) mice, demonstrating on-target action exerted on host cells, not tumour cells. Tumours from treated mice contained increased infiltrating T lymphocytes and reduced myeloid suppressor cells, which were more apoptotic. Single-cell RNA-sequencing analysis revealed upregulation of innate and adaptive immune response pathways in macrophages and T cells. To exert their anti-tumour effects, α2-AR agonists required CD4⁺ T lymphocytes, CD8⁺ T lymphocytes and macrophages. Reconstitution studies in Adra2a-knockout mice indicated that the agonists acted directly on macrophages, increasing their ability to stimulate T lymphocytes. Our results indicate that α2-AR agonists, some of which are available clinically, could substantially improve the clinical efficacy of cancer immunotherapy.

Adrenergic receptors in breast cancer

Breast cancer is the most diagnosed malignancy in women worldwide and in the majority of the countries. Breast cancers are classified on the expression of estrogen and progesterone receptor expression and overexpression of human epidermal growth factor receptor 2 (HER2) as luminal, HER2+ and triple negative breast cancer. The intrinsic molecular subtypes match this classification. Cancer diagnosis and treatment cause distress. In both acute and chronic stress, the secreted catecholamines adrenaline and noradrenaline trigger the "fight-or-flight" response. This chapter focuses on the actions of the β2 and α2 adrenergic receptors in several models of breast cancer. The actions of these receptors depend on the model used to investigate them. The β₂-adrenergic receptors seem to exert a dual action. They can directly act on the epithelial cells inhibiting cell proliferation and migration/invasion and indirectly upon the immune microenvironment. The proportion of β2 receptors in each compartment could, therefore, lean the scale to an inhibition or to an exacerbation of tumor growth, invasion and metastasis. All the work points to a beneficial or neutral action of β-blockers on breast cancer. With respect to α2-adrenergic receptors, the investigation performed by our group suggest that the α2B and the α2C receptors are linked to enhanced cell proliferation and tumor growth acting through both the epithelial and the stromal (fibroblastic) compartments while α2A could be beneficial for patients. Some adrenergic compounds could be repurposed for breast cancer treatment due to their very low side effects and very well-known pharmacology.

The Role of Dexmedetomidine in Tumor-Progressive Factors in the Perioperative Period and Cancer Recurrence: A Narrative Review

Dexmedetomidine, a specific α2 adrenergic receptor agonist, is highly frequently used in the perioperatively for its favorable pharmacology, such as mitigating postoperative cognitive dysfunction. Increasing attention has been recently focused on the effect of whether dexmedetomidine influences cancer recurrence, which urges the discussion of the role of dexmedetomidine in tumor-progressive factors. The pharmacologic characteristics of dexmedetomidine, the tumor-progressive factors in the perioperative period, and the relationships between dexmedetomidine and tumor-progressive factors were described in this review. Available evidence suggests that dexmedetomidine could reduce the degree of immune function suppression, such as keeping the number of CD3+ cells, NK cells, CD4+/CD8+ ratio, and Th1/Th2 ratio stable and decreasing the level of proinflammatory cytokine (interleukin 6 and tumor necrosis factor-alpha) during cancer operations. However, dexmedetomidine exhibits different roles in cell biological behavior depending on cancer cell types. The conclusions on whether dexmedetomidine would influence cancer recurrence could not be currently drawn for the lack of strong clinical evidence. Therefore, this is still a new area that needs further exploration.

Exploring the molecular targets and mechanisms of [10]-Gingerol for treating triple-negative breast cancer using bioinformatics approaches, molecular docking, and in vivo experiments

BACKGROUND

Triple-negative breast cancer (TNBC) is the most aggressive among breast cancer subtypes with the worst prognosis. Ginger is widely used in pharmaceuticals and as food. Its anticancer properties are known, but the mechanism is still unclear. [10]-Gingerol is one of the main phenolic compounds isolated from ginger. Studying the biological effects of [10]-Gingerol is of great significance to understand the efficacy of ginger.

METHODS

In this study, the therapeutic effects of [10]-Gingerol on TNBC cells were studied using network pharmacology, molecular docking, and in vitro experiments, and the target and mechanism of action were explained.

RESULTS

A total of 48 targets of ginger for the treatment of TNBC were found. These targets might interfere with the growth of TNBC by participating in many pathways, such as endocrine resistance, progesterone-mediated oocyte maturation, estrogen signaling pathway, and cellular senescence. Prognostic analyses indicated that the JUN, FASN, ADRB2, ADRA2A, and PGR were the hub genes, while molecular docking predicted the stable binding of ADRB2 protein with drug compounds. Additionally, [10]-Gingerol could induce apoptosis by regulating the caspase activation.

CONCLUSIONS

[10]-Gingerol affects the growth of TNBC through multiple action targets and participating in multiple action pathways. ADRB2 and apoptosis pathways might be important target pathways for [10]-Gingerol in the treatment of TNBC.

Perioperative pain, analgesics and cancer-related outcomes: where do we stand?

Cancer-related pain is one of the most common and debilitating symptoms among cancer patients. Undertreated cancer-related pain interferes with daily activities and increases morbidity and mortality. While opioids continue to play an essential role in treating moderate to severe cancer-related pain, they are associated with many adverse effects including misuse. While preclinical and retrospective studies have shown a negative association between opioid use and cancer outcomes, randomized control trials demonstrate that opioid use does not influence cancer recurrence. Additionally, analgesics and adjuvants used for perioperatively or chronic pain control are unlikely to improve oncological outcomes. This article focuses on the pharmacological management of cancer-related pain and offers an overview regarding the use of these medications perioperatively and the cancer outcomes.

Effect of Dexmedetomidine on Biochemical Recurrence in Patients after Robot-Assisted Laparoscopic Radical Prostatectomy: A Retrospective Study

The usage of dexmedetomidine during cancer surgery in current clinical practice is debatable, largely owing to the differing reports of its efficacy based on cancer type. This study aimed to investigate the effects of dexmedetomidine on biochemical recurrence (BCR) and radiographic progression in patients with prostate cancer, who have undergone robot-assisted laparoscopic radical prostatectomy (RALP). Using follow-up data from two prospective randomized controlled studies, BCR and radiographic progression were compared between individuals who received dexmedetomidine (n = 58) and those who received saline (n = 56). Patients with complete follow-up records between July 2013 and June 2019 were enrolled in this study. There were no significant between-group differences in the number of patients who developed BCR and those who showed positive radiographic progression. Based on the Cox regression analysis, age (p = 0.015), Gleason score ≥ 8 (p < 0.001), and pathological tumor stage 3a and 3b (both p < 0.001) were shown to be significant predictors of post-RALP BCR. However, there was no impact on the dexmedetomidine or control groups. Low-dose administration of dexmedetomidine at a rate of 0.3–0.4 μg/kg/h did not significantly affect BCR incidence following RALP. In addition, no beneficial effect was noted on radiographic progression.

An Intracellular Tripeptide Arg-His-Trp of Serum Origin Detected in MCF-7 Cells Is A Possible Agonist to β2 Adrenoceptor

BACKGROUND

The need of agonists and antagonists of β2 adrenoceptor (β2AR) is warranted in various human disease conditions including cancer, cardiovascular and other metabolic disorders. However, the sources of agonists of β2AR are diverse in nature. Interestingly, there is a complete gap in the exploration of agonists of β2AR from serum that is a well-known component of culture media which supports growth and proliferation of normal and cancer cells in vitro.

METHODS

In this paper, we employed a novel vertical tube gel electrophoresis (VTGE)-assisted purification of intracellular metabolites of MCF-7 cells grown in vitro in complete media with fetal bovine serum (FBS). Intracellular metabolites of MCF-7 cells were then analyzed by LC-HRMS. Identified intracellular tripeptides of FBS origin were evaluated for their molecular interactions with various extracellular and intracellular receptors including β2AR (PDB ID: 2RH1) by employing molecular docking and molecular dynamics simulations (MDS). A known agonist of β2AR, isoproterenol was used as a positive control in molecular docking and MDS analyses.

RESULTS

We report here identification of a few novel intracellular tripeptides, namely Arg-His-Trp, (PubChem CID-145453842), Pro-Ile-Glu, (PubChem CID-145457492), Cys-Gln-Gln, (PubChem CID-71471965), Glu-Glu-Lys, (PubChem CID-11441068) and Gly-Cys-Leu (PubChem CID-145455600) of FBS origin in MCF-7 cells. Molecular docking and MDS analyses revealed that among these molecules, the tripeptide Arg-His-Trp shows a favorable binding affinity with β2AR (-9.8 Kcal/mol). The agonistic effect of Arg-His-Trp is significant and comparable with that of a known agonist of β2AR, isoproterenol.

CONCLUSION

In conclusion, we identified a unique Arg-His-Trp tripeptide of FBS origin in MCF-7 cells by employing a novel approach. This unique tripeptide Arg-His-Trp is suggested to be a potential agonist of β2AR and it may have applications in the context of various human diseases like bronchial asthma and chronic obstructive pulmonary disease (COPD).

Sympathetic activity in breast cancer and metastasis: partners in crime

The vast majority of patients with advanced breast cancer present skeletal complications that severely compromise their quality of life. Breast cancer cells are characterized by a strong tropism to the bone niche. After engraftment and colonization of bone, breast cancer cells interact with native bone cells to hinder the normal bone remodeling process and establish an osteolytic "metastatic vicious cycle". The sympathetic nervous system has emerged in recent years as an important modulator of breast cancer progression and metastasis, potentiating and accelerating the onset of the vicious cycle and leading to extensive bone degradation. Furthermore, sympathetic neurotransmitters and their cognate receptors have been shown to promote several hallmarks of breast cancer, such as proliferation, angiogenesis, immune escape, and invasion of the extracellular matrix. In this review, we assembled the current knowledge concerning the complex interactions that take place in the tumor microenvironment, with a special emphasis on sympathetic modulation of breast cancer cells and stromal cells. Notably, the differential action of epinephrine and norepinephrine, through either α- or β-adrenergic receptors, on breast cancer progression prompts careful consideration when designing new therapeutic options. In addition, the contribution of sympathetic innervation to the formation of bone metastatic foci is highlighted. In particular, we address the remarkable ability of adrenergic signaling to condition the native bone remodeling process and modulate the bone vasculature, driving breast cancer cell engraftment in the bone niche. Finally, clinical perspectives and developments on the use of β-adrenergic receptor inhibitors for breast cancer management and treatment are discussed.

Dexmedetomidine Attenuates LPS-Induced Monocyte-Endothelial Adherence via Inhibiting Cx43/PKC-α/NOX2/ROS Signaling Pathway in Monocytes

Dexmedetomidine is widely used for sedating patients in operation rooms or intensive care units. Its protective functions against oxidative stress, inflammation reaction, and apoptosis have been widely reported. In present study, we explored the effects of dexmedetomidine on monocyte-endothelial adherence. We built lipopolysaccharide- (LPS-) induced monocyte-endothelial adherence models with U937 monocytes and human umbilical vein endothelial cells (HUVECs) and observed the effects of dexmedetomidine on U937-HUVEC adhesion. Specific siRNA was designed to knock-down Connexin43 (Cx43) expression in U937 monocytes. Gö6976, GSK2795039, and NAC were used to inhibit PKC-α, NOX2, and ROS, respectively. Then, we detected whether dexmedetomidine could downregulate Cx43 expression and its downstream PKC-α/NOX2/ROS signaling pathway activation and ultimately result in the decrease of U937-HUVEC adhesion. The results showed that dexmedetomidine, at its clinically relevant concentrations (0.1 nM and 1 nM), could inhibit adhesion of molecule expression (VLA-4 and LFA-1) and U937-HUVEC adhesion. Simultaneously, it also attenuated Cx43 expression in U937 monocytes. With the downregulation of Cx43 expression, the activity of PKC-α and its related NOX2/ROS signaling pathway were reduced. Inhibiting PKC-α/NOX2/ROS signaling pathway with Gö6976, GSK2795039, and NAC, respectively, VLA-4, LFA-1 expression, and U937-HUVEC adhesion were all decreased. In summary, we concluded that dexmedetomidine, at its clinically relevant concentrations (0.1 nM and 1 nM), decreased Cx43 expression in U937 monocytes and PKC-α associated with carboxyl-terminal domain of Cx43 protein. With the downregulation of PKC-α, the NOX2/ROS signaling pathway was inhibited, resulting in the decrease of VLA-4 and LFA-1 expression. Ultimately, U937-HUVEC adhesion was reduced.

Dexmedetomidine promotes the progression of hepatocellular carcinoma through hepatic stellate cell activation

Dexmedetomidine (DEX) is an anesthetic that is widely used in the clinic, and it has been reported to exhibit paradoxical effects in the progression of multiple solid tumors. In this study, we sought to explore the mechanism by which DEX regulates hepatocellular carcinoma (HCC) progression underlying liver fibrosis. We determined the effects of DEX on tumor progression in an orthotopic HCC mouse model of fibrotic liver. A coculture system and a subcutaneous xenograft model involving coimplantation of mouse hepatoma cells (H22) and primary activated hepatic stellate cells (aHSCs) were used to study the effects of DEX on HCC progression. We found that in the preclinical mouse model of liver fibrosis, DEX treatment significantly shortened median survival time and promoted tumor growth, intrahepatic metastasis and pulmonary metastasis. The DEX receptor (ADRA2A) was mainly expressed in aHSCs but was barely detected in HCC cells. DEX dramatically reinforced HCC malignant behaviors in the presence of aHSCs in both the coculture system and the coimplantation mouse model, but DEX alone exerted no significant effects on the malignancy of HCC. Mechanistically, DEX induced IL-6 secretion from aHSCs and promoted HCC progression via STAT3 activation. Our findings provide evidence that the clinical application of DEX may cause undesirable side effects in HCC patients with liver fibrosis.

Dexmedetomidine promotes breast cancer cell migration through Rab11-mediated secretion of exosomal TMPRSS2

Background

Dexmedetomidine (DEX), a highly selective α2-adrenergic receptor agonist, has been reported to increase the malignancy of breast cancer cells in vitro and stimulate tumor growth in mice. Transmembrane protease serine 2 (TMPRSS2) demonstrates proteolytic activity, resulting in degradation of the extracellular matrix (ECM). This study investigated whether and how TMPRSS2 regulates migration of DEX-treated breast cancer cells.

Methods

Breast cancer cell lines MCF-7 and MDA-MB-231 were treated with DEX and scratch assay was performed. Expressions of TMPRSS2, α2-adrenergic receptor, phospho-STAT3^Tyr705, Rab11, and ECM components were assessed using real-time polymerase chain reaction (real-time PCR), Western blotting, and immunofluorescence staining. ELISA and ultracentrifugation were used to quantify secreted exosomal proteins. Knockdown assay was used to inhibit the expression of TMPRSS2 and Rab11.

Results

DEX significantly increased the migration of MCF-7 and MDA-MB-231, which was accompanied by the upregulation and colocalization of TMPRSS2 and α2-adrenergic receptor. Nuclear phospho-STAT3^Tyr705 was increased dramatically following DEX treatment, and TMPRSS2 upregulation was significantly suppressed by the STAT3 inhibitor WP1066. Meanwhile, TMPRSS2 knockdown decreased DEX-induced cellular migration. TMPRSS2 and Rab11 were significantly detected in the media and the isolated exosomes from DEX-treated cells, and their colocalization was also revealed. Rab11 knockdown prevented exosomal TMPRSS2 from increasing in DEX-treated cells. In normal cultured MDA-MB-231, migration was increased by Rab11-positive exosomes isolated from DEX-treated MCF-7. Moreover, transmission electron microscopy showed that Rab11-positive exosomes enriched more components than Rab11-negative exosomes. Additionally, a reduction in ECM components fibronectin, collagen IV, matrix metallopeptidase 16, and Tenascin C was detected after DEX treatment, but was prohibited when TMPRSS2 or Rab11 were knocked down.

Conclusions

This study provides evidence that DEX upregulates TMPRSS2 expression via the activation of α2-adrenergic receptor/STAT3 signaling and promotes TMPRSS2 secretion in exosomes through Rab11, thus resulting in degradation of the ECM, which is responsible for DEX-induced migration of breast cancer cells.

Dexmedetomidine Inhibits Neuroinflammation by Altering Microglial M1/M2 Polarization Through MAPK/ERK Pathway

Neuroinflammation is critical in the pathogenesis of neurological diseases. Microglial pro-inflammatory (M1) and anti-inflammatory (M2) status determines the outcome of neuroinflammation. Dexmedetomidine exerts anti-inflammatory effects in many neurological conditions. Whether dexmedetomidine functions via modulation of microglia M1/M2 polarization remains to be fully elucidated. In the present study, we investigated the anti-inflammatory effects of dexmedetomidine on the neuroinflammatory cell model and explored the potential mechanism. BV2 cells were stimulated with LPS to establish a neuroinflammatory model. The cell viability was determined with MTT assay. NO levels were assessed using a NO detection kit. The protein levels of IL-10, TNF-α, iNOS, CD206, ERK1/2, and pERK1/2 were quantified using Western blotting. LPS significantly increased pro-inflammatory factors TNF-α and NO, and M1 phenotypic marker iNOS, and decreased anti-inflammatory factor IL-10 and M2 phenotypic marker CD206 in BV2 cells. Furthermore, exposure of BV2 cells to LPS significantly raised pERK1/2 expression. Pretreatment with dexmedetomidine attenuated LPS-elicited changes in p-ERK, iNOS, TNF-α, NO, CD206 and IL-10 levels in BV2 cells. However, co-treatment with dexmedetomidine and LM22B-10, an agonist of ERK, reversed dexmedetomidine-elicited changes in p-ERK, iNOS, TNF-α, NO, CD206 and IL-10 levels in LPS-exposed BV2 cells. We, for the first time, showed that dexmedetomidine increases microglial M2 polarization by inhibiting phosphorylation of ERK1/2, by which it exerts anti-inflammatory effects in BV2 cells.

Dexmedetomidine enhances hypoxia-induced cancer cell progression

Dexmedetomidine (DEX) is widely used in perioperative settings for analgesia and sedation; however, little is known about its effects on the hypoxia-induced progression of tumor cells. In the present study, the effects of DEX on hypoxia-induced growth and metastasis of lung cancer cells and colorectal cancer cells was examined. A549 cells and HCT116 cells were treated with normoxia, hypoxia, co-treatment of hypoxia and DEX, and atipamezole (an α₂ adrenoceptor antagonist) for 4 h. The proliferation rate of cells was determined by MTT assays. Cell metastatic potential was evaluated by Transwell assays. Survivin and hypoxia inducible factor (HIF)-1α were detected by western blotting. Matrix metalloproteinase (MMP)-2 and MMP-9 were measured using reverse transcription-quantitative PCR. It was demonstrated that hypoxia treatment promoted the proliferation and may promote the metastasis of the two cancer cell lines. DEX substantially contributed to the survival and aggressiveness of the two cancer cell lines following hypoxia. Furthermore, DEX upregulated the expression of survivin, MMP-2, MMP-9 and HIF-1α in the two cancer cell lines in response to hypoxia. Finally, the effects of DEX on the hypoxia-induced growth and metastatic potential of cancer cells were reversed by atipamezole. Collectively, DEX enhances the hypoxia-induced progression of lung cancer cells and colorectal cancer cells by regulating HIF-1α signaling, which may be associated with the α₂ adrenoceptor pathway.

Effects of dexmedetomidine on glioma cells in the presence or absence of cisplatin

With the extensive use of dexmedetomidine (Dex) in the surgical resection of tumours for its potent sedative and analgesic properties, its effects on various properties of tumours have received increased attention. The study described herein aimed to investigate the effects of Dex on glioma cells in the presence or absence of cisplatin (DDP). Glioma U251 and U87MG cells were treated with different doses (1-50 nM) of Dex for 12 hours, then recultured in a Dex-free medium. In addition, Dex was added to U251 and U87MG cells 12 hours before or simultaneously with a 12-hour DDP treatment. Treatment with Dex increased the viability of both cell lines; this effect continued for at least 24 hours after Dex was removed. A cell invasion assay indicated that Dex inhibited cell invasion at 50 nM, but not at 10 nM. Western blot analysis showed that Dex increased the expression of phosphorylated extracellular-signal-regulated kinase 1/2, phosphoitide 3-kinase and p-AKT, but decreased ROCK protein levels at a dose of 50 nM. Intracellular Ca ²⁺ concentration was decreased by Dex in a dose-dependent manner. DDP toxicity was attenuated by 10 nM Dex added either before or with DDP treatment. However, pretreatment with 50 nM Dex instead enhanced the toxicity of DDP. Single-dose treatment with Dex did not significantly change glioma volume in nude mice, but changed the expression of Ki67 and matrix metalloproteinase-3 in the tumour. In conclusion, this study provides evidence of the regulatory effects of Dex on proliferation, invasion and chemosensitivity of glioma cells, and outlines potential mechanisms for these effects.

Prognostic significance of α- and β2-adrenoceptor gene expression in breast cancer patients

AIMS

Breast cancer is the most frequently diagnosed and leading cause of cancer death among women worldwide. It was classified within molecular intrinsic subtypes: luminal A, luminal B, human epidermal growth factor receptor 2-enriched and basal-like. Epinephrine and norepinephrine, released during stress, bind to adrenoceptors. α₂ -adrenoceptors are encoded by the ADRA2A, ADRA2B and ADRA2C genes and β₂ by ADRB2.

METHODS

We compiled several publicly available Affymetrix gene expression datasets, obtaining a large cohort of 1924 patients with distant metastasis-free survival (DMFS) data and evaluated the association between adrenoceptor expression, clinicopathological markers and outcome.

RESULTS

ADRA2A high expressing tumours also expressed hormone receptors and presented diminished tumour size, grade and not compromised lymph nodes. ADRB2 high expression was found in smaller, low grade, oestrogen receptor-positive tumours. Both were significantly associated with the absence of metastasis. High expression of ADRA2C was positively associated with increased tumour size and metastatic relapse. We observed a significant increase in DMFS of patients with high ADRA2A (hazard ratio 0.54, 95% CI 0.45-0.65, P < .001) and ADRB2 (0.77, 0.64-0.93, P = .006) expression and a decrease with ADRA2C high expression (1.45, 1.16-1.81, P = .001). For patients with luminal tumours, ADRA2A was the only factor that retained its significance as an independent predictor of DMFS while ADRA2C expression was an independent predictor for worse prognosis in basal-like tumours.

CONCLUSIONS

We herein provide new insight for a potential role of ADRA2A and ADRA2C in breast cancer. In low- and medium-income countries, their incorporation to routine immunohistochemistry analysis of biopsies or tumour samples, could provide additional low-cost prognostic factors.

JAK2/STAT5 Pathway Mediates Prolactin-Induced Apoptosis of Lactotropes

Prolactinomas are increasingly viewed as a "problem of signal transduction." Consequently, the identification of factors and signaling pathways that control lactotrope cell turnover is needed in order to encourage new therapeutic developments. We have previously shown that prolactin (PRL) acts as a proapoptotic and antiproliferative factor on lactotropes, maintaining anterior pituitary cell homeostasis, which contrasts with the classical antiapoptotic and/or proliferative actions exerted by PRL in most other target tissues. We aimed to investigate the PRLR-triggered signaling pathways mediating these nonclassical effects of PRL in the pituitary. Our results suggest that (i) the PRLR/Jak2/STAT5 pathway is constitutively active in GH3 cells and contributes to PRL-induced apoptosis by increasing the Bax/Bcl-2 ratio, (ii) PRL inhibits ERK1/2 and Akt phosphorylation, thereby contributing to its proapoptotic effect, and (iii) the PI3K/Akt pathway participates in the PRL-mediated control of lactotrope proliferation. We hypothesize that the alteration of PRL actions in lactotrope homeostasis due to the dysregulation of any of the mechanisms of actions described above may contribute to the pathogenesis of prolactinomas.

Dexmedetomidine reduces oxidative stress and provides neuroprotection in a model of traumatic brain injury via the PGC-1α signaling pathway

The protective effects of dexmedetomidine (DEX) mediated by reductions of oxidative stress, mitochondrial damage and disintegration have been demonstrated in many injury models. However, whether DEX has a beneficial effect on traumatic brain injury (TBI) remains unknown. In this study, the neuroprotective effect of DEX and its potential mechanism were assessed in a model of TBI. DEX treatment relieved encephala edema and neuron cell apoptosis and increased behavioral function. These protective effects were accompanied by upregulation of peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1α) expression. These findings imply that DEX protects neurons following TBI, possibly by activating the PGC-1α pathway. The data will help clarify the mechanisms responsible for the anti-apoptosis effect of DEX with possible involvement of the PGC-1α pathway.

Midazolam and Dexmedetomidine Affect Neuroglioma and Lung Carcinoma Cell Biology In Vitro and In Vivo

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What We Already Know about This Topic

What This Article Tells Us That Is New

Background

Several factors within the perioperative period may influence postoperative metastatic spread. Dexmedetomidine and midazolam are widely used general anesthetics during surgery. The authors assessed their effects on human lung carcinoma (A549) and neuroglioma (H4) cell lines in vitro and in vivo.

Methods

Cell proliferation and migration were measured after dexmedetomidine (0.001 to 10 nM) or midazolam (0.01 to 400 μM) treatment. Expression of cell cycle and apoptosis markers were assessed by immunofluorescence. Mitochondrial membrane potential and reactive oxygen species were measured by JC-1 staining and flow cytometry. Antagonists atipamezole and flumazenil were used to study anesthetic mechanisms of action. Tumor burden after anesthetic treatment was investigated with a mouse xenograft model of lung carcinoma.

Results

Dexmedetomidine (1 nM) promoted cell proliferation (2.9-fold in A549 and 2-fold in H4 cells vs. vehicle, P &lt; 0.0001; n = 6), migration (2.2-fold in A549 and 1.9-fold in H4 cells vs. vehicle, P &lt; 0.0001; n = 6), and upregulated antiapoptotic proteins in vitro. In contrast, midazolam (400 μM) suppressed cancer cell migration (2.6-fold in A549 cells, P &lt; 0.0001; n = 4), induced apoptosis via the intrinsic mitochondrial pathway, decreased mitochondrial membrane potential, and increased reactive oxygen species expression in vitro—effects partly attributable to peripheral benzodiazepine receptor activation. Furthermore, midazolam significantly reduced tumor burden in mice (1.7-fold vs. control; P &lt; 0.05; n = 6 per group).

Conclusions

Midazolam possesses antitumorigenic properties partly mediated by the peripheral benzodiazepine receptor, whereas dexmedetomidine promotes cancer cell survival through signaling via the α2-adrenoceptor in lung carcinoma and neuroglioma cells.