β2-AR regulates the expression of AKR1B1 in human pancreatic cancer cells and promotes their proliferation via the ERK1/2 pathway

The Role of Claudin-1 in Enhancing Pancreatic Cancer Aggressiveness and Drug Resistance via Metabolic Pathway Modulation

BACKGROUND/OBJECTIVES

Pancreatic ductal adenocarcinoma is a lethal malignancy, necessitating an understanding of its molecular mechanisms for the development of new therapeutic strategies. The tight junction protein claudin-1, known to influence cellular functions in various cancers and is considered a therapeutic target, remains unclear in pancreatic cancer.

METHODS

This study assessed claudin-1 expression in resected pancreatic cancer samples, public databases, and pancreatic cancer cell lines. Claudin-1 knockout with CRISPR/Cas9 on poorly differentiated pancreatic cancer cell lines and a proteome analysis were performed to investigate the intracellular mechanisms of claudin-1.

RESULTS

Claudin-1 was markedly overexpressed in pancreatic ductal adenocarcinoma and intraepithelial neoplasia compared to normal ducts, and high claudin-1 levels were an independent predictor of poor prognosis. Claudin-1 knockout diminished cell proliferation, migration, invasion, and chemoresistance in pancreatic ductal adenocarcinoma. Proteome analysis revealed the significant downregulation of aldo-keto reductase family proteins (AKR1C2, AKR1C3, and AKR1B1) in claudin-1 knockout cells, which are linked to metabolic pathways. Aldo-keto reductase knockdown reduced chemoresistance, proliferation, and invasion in these cell lines.

CONCLUSIONS

These findings indicate that the abnormal expression of claudin-1 promotes tumor progression and drug resistance through its interaction with aldo-keto reductase proteins, highlighting claudin-1 and aldo-keto reductase family proteins as potential biomarkers and therapeutic targets for pancreatic cancer.

Exploring the biological mechanism and clinical value of perineural invasion in pancreatic cancer

Pancreatic cancer (PC) is an extremely aggressive malignancy, with a 5-year survival rate of only 13 %. Perineural invasion (PNI) is a hallmark pathological feature of PC and is observed in almost all cases. Accordingly, PC ranks highly among solid tumors in terms of PNI incidence. The interaction between PC and the nervous system plays a pivotal role in tumor growth and metastasis. In PC, PNI is a key driver of local tumor progression, distant metastasis, and poor prognosis. Clarification of tumor-nerve crosstalk and the underlying molecular mechanisms is needed to facilitate the development of new therapeutic strategies to slow PC progression and alleviate PNI-associated symptoms. In this review, we present a comprehensive overview of the manifestations and characteristics of PNI in PC, summarize the molecular networks that regulate PNI, examine the relationship between PNI and the tumor microenvironment, and discuss the current research challenges and future directions in this critical area.

β‑adrenergic receptor activation promotes the proliferation of HepG2 cells via the ERK1/2/CREB pathways

Primary liver cancer is one of the most frequently diagnosed malignant tumors seen in clinics, and typically exhibits aggressive invasive behaviors, a poor prognosis, and is associated with high mortality rates. Long-term stress exposure causes norepinephrine (NE) release and activates the β-Adrenergic receptor (β-AR), which in turn exacerbates the occurrence and development of different types of cancers; however, the molecular mechanisms of β-AR in liver cancer are not fully understood. In the present study, reverse transcription (RT)-PCR and RT-quantitative PCR showed that β-AR expression was upregulated in human liver cancer cells (HepG2) compared with normal liver cells (LO2). Moreover, NE treatment promoted the growth of HepG2 cells, which could be blocked by propranolol, a β-AR antagonist. Notably, NE had no significant effect on the migration and epithelial-mesenchymal transition in HepG2 cells. Further experiments revealed that NE increased the phosphorylation levels of the extracellular signal-regulated kinase 1/2 (ERK1/2) and cyclic adenosine monophosphate response element-binding protein (CREB), while inhibition of ERK1/2 and CREB activation significantly blocked NE-induced cell proliferation. In summary, the findings of the present study suggested that β-adrenergic receptor activation promoted the proliferation of HepG2 cells through ERK1/2/CREB signaling pathways.

Bioinformatics Analysis Reveals the Vital Role of AKR1B1 in Immune Infiltration and Clinical Outcomes of Gastric Cancer

Infiltrated immune cells are an important constitute of tumor microenvironment, which exert complex effects on gastric cancer (GC) pathogenesis and progression. By using weighted gene co-expression network analysis, integrating the data from The Cancer Genome Atlas-stomach adenocarcinoma and GSE62254, we identify Aldo-Keto Reductase Family 1 Member B (AKR1B1) as a hub gene for immune regulation in GC. Notably, AKR1B1 is associated with higher immune infiltration and worse histologic grade of GC. In addition, AKR1B1 is an independent factor for predicting the survival rate of GC patients. In vitro experiments further demonstrated that AKR1B1-overexpressed THP-1-derived macrophages promoted the proliferation and migration of GC cells. Taken together, AKR1B1 plays an important role in GC progression by regulating immune microenvironment, which could be a biomarker for predicting GC prognosis as well as a potential therapeutic target for GC treatment.

Emerging Roles of the Nervous System in Gastrointestinal Cancer Development

Simple Summary

Nerve–cancer cross-talk has increasingly become a focus of the oncology field, particularly in gastrointestinal (GI) cancers. The indispensable roles of the nervous system in GI tumorigenesis and malignancy have been dissected by epidemiological, experimental animal and mechanistic data. Herein, we review and integrate recent discoveries linking the nervous system to GI cancer initiation and progression, and focus on the molecular mechanisms by which nerves and neural receptor pathways drive GI malignancy.

Abstract

Our understanding of the fascinating connection between nervous system and gastrointestinal (GI) tumorigenesis has expanded greatly in recent years. Recent studies revealed that neurogenesis plays an active part in GI tumor initiation and progression. Tumor-driven neurogenesis, as well as neurite outgrowth of the pre-existing peripheral nervous system (PNS), may fuel GI tumor progression via facilitating cancer cell proliferation, chemoresistance, invasion and immune escape. Neurotransmitters and neuropeptides drive the activation of various oncogenic pathways downstream of neural receptors within cancer cells, underscoring the importance of neural signaling pathways in GI tumor malignancy. In addition, neural infiltration also plays an integral role in tumor microenvironments, and contributes to an environment in favor of tumor angiogenesis, immune evasion and invasion. Blockade of tumor innervation via denervation or pharmacological agents may serve as a promising therapeutic strategy against GI tumors. In this review, we summarize recent findings linking the nervous system to GI tumor progression, set the spotlight on the molecular mechanisms by which neural signaling fuels cancer aggressiveness, and highlight the importance of targeting neural mechanisms in GI tumor therapy.

Integration of metabolites from meta-analysis with transcriptome reveals enhanced SPHK1 in PDAC with a background of pancreatitis

BACKGROUND

Pathophysiology of transformation of inflammatory lesions in chronic pancreatitis (CP) to pancreatic ductal adenocarcinoma (PDAC) is not clear.

METHODS

We conducted a systematic review, meta-analysis of circulating metabolites, integrated this data with transcriptome analysis of human pancreatic tissues and validated using immunohistochemistry. Our aim was to establish biomarker signatures for early malignant transformation in patients with underlying CP and identify therapeutic targets.

RESULTS

Analysis of 19 studies revealed AUC of 0.86 (95% CI 0.81-0.91, P < 0.0001) for all the altered metabolites (n = 88). Among them, lipids showed higher differentiating efficacy between PDAC and CP; P-value (< 0.0001). Pathway enrichment analysis identified sphingomyelin metabolism (impact value-0.29, FDR of 0.45) and TCA cycle (impact value-0.18, FDR of 0.06) to be prominent pathways in differentiating PDAC from CP. Mapping circulating metabolites to corresponding genes revealed 517 altered genes. Integration of these genes with transcriptome data of CP and PDAC with a background of CP (PDAC-CP) identified three upregulated genes; PIGC, PPIB, PKM and three downregulated genes; AZGP1, EGLN1, GNMT. Comparison of CP to PDAC-CP and PDAC-CP to PDAC identified upregulation of SPHK1, a known oncogene.

CONCLUSIONS

Our analysis suggests plausible role for SPHK1 in development of pancreatic adenocarcinoma in long standing CP patients. SPHK1 could be further explored as diagnostic and potential therapeutic target.

A Potential Prognostic Biomarker for Glioma: Aldo-Keto Reductase Family 1 Member B1

Aldo-keto reductase family 1 member B1 (AKR1B1) plays a vital role in tumor development and is involved in the tumor immune process. However, its role in glioma cell is poorly studied. This study's aim was to assess the role of AKR1B1 in glioma through bioinformatics analysis. The AKR1B1 expression data and corresponding clinical data of glioma were collected from the Cancer Genome Atlas (TCGA) database. The R packages were used for data integration, extraction, analysis, and visualization. According to the median value of the risk score, all patients were divided into high-risk and low-risk groups to draw the Kaplan-Meier (KM) survival curves and to explore the level of immune infiltration. The expression of AKR1B1 was significantly elevated in glioma tissues compared to normal tissues (P < 0.001). The high expression of AKR1B1 was significantly associated with WHO grade (P < 0.001), IDH status (P < 0.001), 1p/19q codeletion (P < 0.001), primary therapy outcome (P = 0.004), and age (P < 0.05). Kaplan-Meier survival analysis found that OS (HR = 3.75, P < 0.001), DSS (HR = 3.85, P < 0.001), and PFI (HR = 2.76, P < 0.001) were lower in patients with glioma with high AKR1B1 expression than in the group with low AKR1B1 expression. Based on GESA, six pathways (including interferon gamma signaling, signaling by interleukins, cell cycle checkpoints, cytokine receptor interaction, cell adhesion molecules (CAMs), and cell surface interactions) at the vascular wall were identified as significantly different between the two groups. Moreover, highly expressed AKR1B1 was associated with immune cell infiltration. AKR1B1 plays a key role in glioma progression and prognosis and, therefore, serves as a potential biomarker for prediction of patients' survival.

Anticancer Activity of Ω-6 Fatty Acids through Increased 4-HNE in Breast Cancer Cells

Simple Summary

Epidemiological evidence suggests that breast cancer risk is lowered by Ω-3 and increased by Ω-6 polyunsaturated fatty acids (PUFAs). Paradoxically, the Ω-6 PUFA metabolite 4-hydroxynonenal (4-HNE) inhibits cancer cell growth. This duality prompted us to study whether arachidonic acid (AA) would enhance doxorubicin (dox) cytotoxicity towards breast cancer cells. We found that supplementing AA or inhibiting 4-HNE metabolism potentiated doxorubicin (dox) toxicity toward Her2-dependent breast cancer but spared myocardial cells. Our results suggest that Ω-6 PUFAs could improve outcomes of dox chemotherapy in Her2-overexpressing breast cancer.

Abstract

Her2-amplified breast cancers resistant to available Her2-targeted therapeutics continue to be a challenge in breast cancer therapy. Dox is the mainstay of chemotherapy of all types of breast cancer, but its usefulness is limited by cumulative cardiotoxicity. Because oxidative stress caused by dox generates the pro-apoptotic Ω-6 PUFA metabolite 4-hydroxynonenal (4-HNE), we surmised that Ω-6 PUFAs would increase the effectiveness of dox chemotherapy. Since the mercapturic acid pathway enzyme RALBP1 (also known as RLIP76 or Rlip) that limits cellular accumulation of 4-HNE also mediates dox resistance, the combination of Ω-6 PUFAs and Rlip depletion could synergistically improve the efficacy of dox. Thus, we studied the effects of the Ω-6 PUFA arachidonic acid (AA) and Rlip knockdown on the antineoplastic activity of dox towards Her2-amplified breast cancer cell lines SK-BR-3, which is sensitive to Her2 inhibitors, and AU565, which is resistant. AA increased lipid peroxidation, 4-HNE generation, apoptosis, cellular dox concentration and dox cytotoxicity in both cell lines while sparing cultured immortalized cardiomyocyte cells. The known functions of Rlip including clathrin-dependent endocytosis and dox efflux were inhibited by AA. Our results support a model in which 4-HNE generated by AA overwhelms the capacity of Rlip to defend against apoptosis caused by dox or 4-HNE. We propose that Ω-6 PUFA supplementation could improve the efficacy of dox or Rlip inhibitors for treating Her2-amplified breast cancer.

An Advanced Systems Pharmacology Strategy Reveals AKR1B1, MMP2, PTGER3 as Key Genes in the Competing Endogenous RNA Network of Compound Kushen Injection Treating Gastric Carcinoma by Integrated Bioinformatics and Experimental Verification

Gastric carcinoma (GC) is a severe tumor of the digestive tract with high morbidity and mortality and poor prognosis, for which novel treatment options are urgently needed. Compound Kushen injection (CKI), a classical injection of Chinese medicine, has been widely used to treat various tumors in clinical practice for decades. In recent years, a growing number of studies have confirmed that CKI has a beneficial therapeutic effect on GC, However, there are few reports on the potential molecular mechanism of action. Here, using systems pharmacology combined with proteomics analysis as a core concept, we identified the ceRNA network, key targets and signaling pathways regulated by CKI in the treatment of GC. To further explore the role of these key targets in the development of GC, we performed a meta-analysis to compare the expression differences between GC and normal gastric mucosa tissues. Functional enrichment analysis was further used to understand the biological pathways significantly regulated by the key genes. In addition, we determined the significance of the key genes in the prognosis of GC by survival analysis and immune infiltration analysis. Finally, molecular docking simulation was performed to verify the combination of CKI components and key targets. The anti-gastric cancer effect of CKI and its key targets was verified by in vivo and in vitro experiments. The analysis of ceRNA network of CKI on GC revealed that the potential molecular mechanism of CKI can regulate PI3K/AKT and Toll-like receptor signaling pathways by interfering with hub genes such as AKR1B1, MMP2 and PTGERR3. In conclusion, this study not only partially highlighted the molecular mechanism of CKI in GC therapy but also provided a novel and advanced systems pharmacology strategy to explore the mechanisms of traditional Chinese medicine formulations.

The Role of the FOXO1/β2-AR/p-NF-κB p65 Pathway in the Development of Endometrial Stromal Cells in Pregnant Mice under Restraint Stress

Restraint stress causes various maternal diseases during pregnancy. β₂-Adrenergic receptor (β₂-AR) and Forkhead transcription factor class O 1 (FOXO1) are critical factors not only in stress, but also in reproduction. However, the role of FOXO1 in restraint stress, causing changes in the β₂-AR pathway in pregnant mice, has been unclear. The aim of this research was to investigate the β₂-AR pathway of restraint stress and its impact on the oxidative stress of the maternal uterus. In the study, maternal mice were treated with restraint stress by being restrained in a transparent and ventilated device before sacrifice on Pregnancy Day 5 (P5), Pregnancy Day 10 (P10), Pregnancy Day 15 (P15), and Pregnancy Day 20 (P20) as well as on Non-Pregnancy Day 5 (NP5). Restraint stress augmented blood corticosterone (CORT), norepinephrine (NE), and blood glucose levels, while oestradiol (E2) levels decreased. Moreover, restraint stress increased the mRNA levels of the FOXO family, β₂-AR, and even the protein levels of FOXO1 and β₂-AR in the uterus and ovaries. Furthermore, restraint stress increased uterine oxidative stress level. In vitro, the protein levels of FOXO1 were also obviously increased when β₂-AR was activated in endometrial stromal cells (ESCs). In addition, phosphorylated-nuclear factor kappa-B p65 (p-NF-κB p65) and its target genes decreased significantly when FOXO1 was inhibited. Overall, it can be said that the β₂-AR/FOXO1/p-NF-κB p65 pathway was activated when pregnant mice were under restraint stress. This study provides a scientific basis for the origin of psychological stress in pregnant women.

A Holistic Perspective: Exosomes Shuttle between Nerves and Immune Cells in the Tumor Microenvironment

One of the limitations of cancer research has been the restricted focus on tumor cells and the omission of other non-malignant cells that are constitutive elements of this systemic disease. Current research is focused on the bidirectional communication between tumor cells and other components of the tumor microenvironment (TME), such as immune and endothelial cells, and nerves. A major success of this bidirectional approach has been the development of immunotherapy. Recently, a more complex landscape involving a multi-lateral communication between the non-malignant components of the TME started to emerge. A prime example is the interplay between immune and endothelial cells, which led to the approval of anti-vascular endothelial growth factor-therapy combined with immune checkpoint inhibitors and classical chemotherapy in non-small cell lung cancer. Hence, a paradigm shift approach is to characterize the crosstalk between different non-malignant components of the TME and understand their role in tumorigenesis. In this perspective, we discuss the interplay between nerves and immune cells within the TME. In particular, we focus on exosomes and microRNAs as a systemic, rapid and dynamic communication channel between tumor cells, nerves and immune cells contributing to cancer progression. Finally, we discuss how combinatorial therapies blocking this tumorigenic cross-talk could lead to improved outcomes for cancer patients.

Targeting β2-Adrenergic Receptors Shows Therapeutical Benefits in Clear Cell Renal Cell Carcinoma from Von Hippel-Lindau Disease

Von Hippel–Lindau (VHL), is a rare autosomal dominant inherited cancer in which the lack of VHL protein triggers the development of multisystemic tumors such us retinal hemangioblastomas (HB), CNS-HB, and clear cell renal cell carcinoma (ccRCC). ccRCC ranks third in terms of incidence and first in cause of death. Standard systemic therapies for VHL-ccRCC have shown limited response, with recurrent surgeries being the only effective treatment. Targeting of β2-adrenergic receptor (ADRB) has shown therapeutic antitumor benefits on VHL-retinal HB (clinical trial) and VHL-CNS HB (in vitro). Therefore, the in vitro and in vivo antitumor benefits of propranolol (ADRB-1,2 antagonist) and ICI-118,551 (ADRB-2 antagonist) on VHL^−/− ccRCC primary cultures and 786-O tumor cell lines have been addressed. Propranolol and ICI-118,551 activated apoptosis inhibited gene and protein expression of HIF-2α, CAIX, and VEGF, and impaired partially the nuclear internalization of HIF-2α and NFĸB/p65. Moreover, propranolol and ICI-118,551 reduced tumor growth on two in vivo xenografts. Finally, ccRCC patients receiving propranolol as off-label treatment have shown a positive therapeutic response for two years on average. In summary, propranolol and ICI-118,551 have shown antitumor benefits in VHL-derived ccRCC, and since ccRCCs comprise 63% of the total RCCs, targeting ADRB2 becomes a promising drug for VHL and other non-VHL tumors.

The AKR1B1 inhibitor epalrestat suppresses the progression of cervical cancer

Cervical cancer is the leading cause of cancer-related death among women worldwide. Identifying an effective treatment with fewer side effects is imperative, because all of the current treatments have unique disadvantages. Aldo-keto reductase family 1 member B1 (AKR1B1) is highly expressed in various cancers and is associated with tumor development, but has not been studied in cervical cancer. In the current study, we used CRISPR/Cas9 technology to establish a stable HeLa cell line with AKR1B1 knockout. In vitro, AKR1B1 knockout inhibited the proliferation, migration and invasion of HeLa cells, providing evidence that AKR1B1 is an innovative therapeutic target. Notably, the clinically used epalrestat, an inhibitor of aldose reductases, including AKR1B1, had the same effect as AKR1B1 knockout on HeLa cells. This result suggests that epalrestat could be used in the clinical treatment of cervical cancer, a prospect that undoubtedly requires further research. Moreover, aiming to determine the underlying regulatory mechanism of AKR1B1, we screened a series of differentially regulated genes (DEGs) by RNA sequencing and verified selected DEGs by quantitative RT-PCR. In addition, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of the DEGs revealed a correlation between AKR1B1 and cancer. In summary, epalrestat inhibits the progression of cervical cancer by inhibiting AKR1B1, and thus may be a new drug for the clinical treatment of cervical cancer.

Silencing of Long Non-Coding RNA (LncRNA) Non-Coding RNA Activated by DNA Damage (NORAD) Inhibits Proliferation, Invasion, Migration, and Promotes Apoptosis of Glioma Cells via Downregulating the Expression of AKR1B1

Background

We aimed to investigate the functions of long non-coding RNA (lncRNA) non-coding RNA activated by DNA damage (NORAD) in glioma and identify the potential mechanisms.

Material/Methods

The expression of NORAD and AKR1B1 in human glioma cell lines were examined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Then, cell proliferation, invasion, and migration were tested by Cell Counting Kit-8 (CCK-8), colony formation assay, Transwell, and scratch wound healing assay after NORAD silencing. Meanwhile, western blotting was utilized to measure the expression of migration-related proteins. Apoptosis of glioma cells was detected using flow cytometry and apoptosis-related proteins expression was determined. Moreover, the correlation between NORAD and AKR1B1 was verified by RNA-binding protein immunoprecipitation (RIP assay). After co-transfection with AKR1B1 overexpressed plasmid and NORAD siRNA, cell proliferation, invasion, migration, and apoptosis were examined again. Furthermore, the expression of proteins in extracellular signal-regulated kinase (ERK) signaling was tested using western blotting.

Results

The results revealed that NORAD and AKR1B1 were highly expressed in glioma cells. NORAD silencing inhibited proliferation, invasion and migration but promoted apoptosis of glioma cells, accompanied by the expression changes of migration- and apoptosis-related proteins. However, after co-transfection with AKR1B1 pcDNA3.1 in NORAD silencing cells, the effects of NORAD silencing on proliferation, invasion, migration, and apoptosis were attenuated. Consistently, the expression of phosphorylated ERK (p-ERK) was decreased after NORAD silencing, which were reversed following AKR1B1 overexpression.

Conclusions

These findings demonstrated that NORAD silencing suppressed proliferation, invasion, and migration and boosted apoptosis of glioma cells via downregulating the AKR1B1 expression, which may provide a potential therapeutic target for glioma treatment.

Role of aldo-keto reductase family 1 member B1 (AKR1B1) in the cancer process and its therapeutic potential

The role of aldo‐keto reductase family 1 member B1 (AKR1B1) in cancer is not totally clear but growing evidence is suggesting to have a great impact on cancer progression. AKR1B1 could participate in a complicated network of signalling pathways, proteins and miRNAs such as mir‐21 mediating mechanisms like inflammatory responses, cell cycle, epithelial to mesenchymal transition, cell survival and apoptosis. AKR1B1 has been shown to be mostly overexpressed in cancer. This overexpression has been associated with inflammatory mediators including nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NFκB), cell cycle mediators such as cyclins and cyclin‐dependent kinases (CDKs), survival proteins and pathways like mammalian target of rapamycin (mTOR) and protein kinase B (PKB) or AKT, and other regulatory factors in response to reactive oxygen species (ROS) and prostaglandin synthesis. In addition, inhibition of AKR1B1 has been shown to mostly have anti‐cancer effects. Several studies have also suggested that AKR1B1 inhibition as an adjuvant therapy could render tumour cells more sensitive to anti‐cancer therapy or alleviate the adverse effects of therapy. AKR1B1 could also be considered as a potential cancer diagnostic biomarker since its promoter has shown high levels of methylation. Although pre‐clinical investigations on the role of AKR1B1 in cancer and the application of its inhibitors have shown promising results, the lack of clinical studies on AKR1B1 inhibitors has hampered the use of these drugs to treat cancer. Thus, there is a need to conduct more clinical studies on the application of AKR1B1 inhibitors as adjuvant therapy on different cancers.

The Expression and Clinical Significance of Aldo-Keto Reductase 1 Member B1 in Gastric Carcinoma

To study the expression of aldo-keto reductase 1 member B1 (AKR1B1) in gastric carcinoma (GC), the correlation between AKR1B1 and the clinicopathological characteristics of GC patients, and provide reference for the diagnosis and prognosis of GC patients. One hundred thirty-six patients with GC were collected, and the expression level of AKR1B1 in GC and adjacent tissues was detected by immunohistochemistry assays. The clinicopathological features and prognosis of GC patients were collected to analyze the relationship with AKR1B1 expression. The positive expression of AKR1B1 in GC tissues was significantly higher than that of adjacent nontumor tissues. The difference of AKR1B1 expression between GC tissues and paired adjacent nontumor tissues was statistically significant (p < 0.001). AKR1B1 was closely related to tumor size, regional lymph node (N), metastases (M), and tumor-node-metastasis (TNM) stage (p < 0.05). The overall survival of patients with low expression of AKR1B1 was significantly better than that of patients with high expression of AKR1B1 by Kaplan-Meier survival analysis (p < 0.001). AKR1B1 plays an important role in the occurrence and development of GC, and it has a certain reference value for the prognosis of GC patients.

β adrenergic receptor modulated signaling in glioma models: promoting β adrenergic receptor-β arrestin scaffold-mediated activation of extracellular-regulated kinase 1/2 may prove to be a panacea in the treatment of intracranial and spinal malignancy and extra-neuraxial carcinoma

Neoplastically transformed astrocytes express functionally active cell surface β adrenergic receptors (βARs). Treatment of glioma models in vitro and in vivo with β adrenergic agonists variably amplifies or attenuates cellular proliferation. In the majority of in vivo models, β adrenergic agonists generally reduce cellular proliferation. However, treatment with β adrenergic agonists consistently reduces tumor cell invasive potential, angiogenesis, and metastasis. β adrenergic agonists induced decreases of invasive potential are chiefly mediated through reductions in the expression of matrix metalloproteinases types 2 and 9. Treatment with β adrenergic agonists also clearly reduce tumoral neoangiogenesis, which may represent a putatively useful mechanism to adjuvantly amplify the effects of bevacizumab. Bevacizumab is a monoclonal antibody targeting the vascular endothelial growth factor receptor. We may accordingly designate βagonists to represent an enhancer of bevacizumab. The antiangiogenic effects of β adrenergic agonists may thus effectively render an otherwise borderline effective therapy to generate significant enhancement in clinical outcomes. β adrenergic agonists upregulate expression of the major histocompatibility class II DR alpha gene, effectively potentiating the immunogenicity of tumor cells to tumor surveillance mechanisms. Authors have also demonstrated crossmodal modulation of signaling events downstream from the β adrenergic cell surface receptor and microtubular polymerization and depolymerization. Complex effects and desensitization mechanisms of the β adrenergic signaling may putatively represent promising therapeutic targets. Constant stimulation of the β adrenergic receptor induces its phosphorylation by β adrenergic receptor kinase (βARK), rendering it a suitable substrate for alternate binding by β arrestins 1 or 2. The binding of a β arrestin to βARK phosphorylated βAR promotes receptor mediated internalization and downregulation of cell surface receptor and contemporaneously generates a cell surface scaffold at the βAR. The scaffold mediated activation of extracellular regulated kinase 1/2, compared with protein kinase A mediated activation, preferentially favors cytosolic retention of ERK1/2 and blunting of nuclear translocation and ensuant pro-transcriptional activity. Thus, βAR desensitization and consequent scaffold assembly effectively retains the cytosolic homeostatic functions of ERK1/2 while inhibiting its pro-proliferative effects. We suggest these mechanisms specifically will prove quite promising in developing primary and adjuvant therapies mitigating glioma growth, angiogenesis, invasive potential, and angiogenesis. We suggest generating compounds and targeted mutations of the β adrenergic receptor favoring β arrestin binding and scaffold facilitated activation of ERK1/2 may hold potential promise and therapeutic benefit in adjuvantly treating most or all cancers. We hope our discussion will generate fruitful research endeavors seeking to exploit these mechanisms.