Phosphorylation Regulates CAP1 (Cyclase-Associated Protein 1) Functions in the Motility and Invasion of Pancreatic Cancer Cells

Targeting protein modification: a new direction for immunotherapy of pancreatic cancer

Post-translational modifications (PTMs) alter protein conformation by covalently attaching functional groups to substrates, influencing their biological activity, mechanisms of action, and functional performance. PTMs and their interactions are essential to many critical signal transduction processes, including tumor transformation, cancer progression, and metastasis in pancreatic cancer. Additionally, advancements in tumor immunotherapy indicate that PTMs are essential in immune cell activation, transport, and energy metabolism. This study aimed to investigate the effects of different PTMs on immunotherapy for pancreatic cancer, providing new perspectives and suggesting directions for future research.

Small molecule protein assembly modulators with pan-cancer therapeutic efficacy

Two structurally unrelated small molecule chemotypes, represented by compounds PAV-617 and PAV-951, with antiviral activity in cell culture against Mpox virus (formerly known as monkeypox virus) and human immunodeficiency virus (HIV) respectively, were studied for anti-cancer efficacy. Each exhibited apparent pan-cancer cytotoxicity with reasonable pharmacokinetics. Non-toxicity is demonstrated in a non-cancer cell line and in mice at doses achieving drug exposure at active concentrations. Anti-tumour properties of both chemotypes were validated in mouse xenografts against A549 human lung cancer and, for one of the chemotypes, against HT-29 colorectal cancer. The targets of these compounds are unconventional: each binds to a different transient, energy-dependent multi-protein complex. Treatment with these compounds alters the target multi-protein complexes in a manner that appears to remove a block, crucial for cancer survival and progression, on a homeostatic linkage between uncontrolled proliferation and apoptosis. These compounds provide starting points for development of novel, next-generation, non-toxic, pan-cancer therapeutics.

Exosome and lipid metabolism-related genes in pancreatic adenocarcinoma: a prognosis analysis

OBJECTIVE

The purpose of the study was to investigate the role of exosome and lipid metabolism-related genes (EALMRGs) mRNA levels in the diagnosis and prognosis of Pancreatic Adenocarcinoma (PAAD).

METHODS

The mRNA expression pattern of PAAD and pan-cancers with prognostic data were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. EALMRGs were acquired from GeneCards and MSigDB database after merging and deduplication. Prognostic EALMRGs were screened through univariate COX regression analysis, and a prognostic model was constructed based on these genes by least absolute shrinkage and selection operator (LASSO) regression. The prognostic value of EALMRGs was then validated in pan-cancer data. The time characteristics ROC curve analysis was performed to evaluate the effectiveness of the prognostic genes.

RESULTS

We identified 5 hub genes (ABCB1, CAP1, EGFR, PPARG, SNCA) according to high and low-risk groups of prognoses. The risk formula was verified in three other cohort of pancreatic cancer patients and was explored in pan-cancer data. Additionally, T cell and dendritic cell infiltration was significantly increased in low-risk group. The expression of the 5 hub genes was also identified in single-cell sequencing data of pancreatic cancer with pivotal pathways. Additionally, functional enrichment analysis based on pancreatic cancer data in pancreatic cancer showed that protein serine/threonine kinase activity, focal adhesion, actin binding, cell-substrate junction, organic acid transport, and regulation of transporter activity were significant related to the expression of genes in EALMRGs.

CONCLUSIONS

Our risk formula shows potential prognostic value in multiple cancers and manifest pivotal alterations in immune infiltration and biological pathway in pancreatic cancer.

CAP1 (cyclase-associated protein 1) mediates the cyclic AMP signals that activate Rap1 in stimulating matrix adhesion of colon cancer cells

We previously reported that CAP1 (Cyclase-Associated Protein 1) regulates matrix adhesion in mammalian cells through FAK (Focal Adhesion Kinase). More recently, we discovered a phosphor-regulation mechanism for CAP1 through the Ser307/Ser309 tandem site that is of critical importance for all CAP1 functions. However, molecular mechanisms underlying the CAP1 function in adhesion and its regulation remain largely unknown. Here we report that Rap1 also facilitates the CAP1 function in adhesion, and more importantly, we identify a novel signaling pathway where CAP1 mediates the cAMP signals, through the cAMP effectors Epac (Exchange proteins directly activated by cAMP) and PKA (Protein Kinase A), to activate Rap1 in stimulating matrix adhesion in colon cancer cells. Knockdown of CAP1 led to opposite adhesion phenotypes in SW480 and HCT116 colon cancer cells, with reduced matrix adhesion and reduced FAK and Rap1 activities in SW480 cells while it stimulated matrix adhesion as well as FAK and Rap1 activities in HCT116 cells. Importantly, depletion of CAP1 abolished the stimulatory effects of the cAMP activators forskolin and isoproterenol, as well as that of Epac and PKA, on matrix adhesion in both cell types. Our results consistently support a required role for CAP1 in the cAMP activation of Rap1. Identification of the key role for CAP1 in linking the major second messenger cAMP to activation of Rap1 in stimulating adhesion, which may potentially also regulate proliferation in other cell types, not only vertically extends our knowledge on CAP biology, but also carries important translational potential for targeting CAP1 in cancer therapeutics.

Glycogen Synthase Kinase 3β: A True Foe in Pancreatic Cancer

Glycogen synthase kinase 3 beta (GSK-3β) is a serine/threonine protein kinase involved in multiple normal and pathological cell functions, including cell signalling and metabolism. GSK-3β is highly expressed in the onset and progression of multiple cancers with strong involvement in the regulation of proliferation, apoptosis, and chemoresistance. Multiple studies showed pro- and anti-cancer roles of GSK-3β creating confusion about the benefit of targeting GSK-3β for treating cancer. In this mini-review, we focus on the role of GSK-3β in pancreatic cancer. We demonstrate that the proposed anti-cancer roles of GSK-3β are not relevant to pancreatic cancer, and we argue why GSK-3β is, indeed, a very promising therapeutic target in pancreatic cancer.

Chromenopyrimidinone exhibit antitumor effects through inhibition of CAP1 (Adenylyl cyclase-associated protein 1) expression in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most malignant human cancers, with a high mortality rate worldwide. Within an HCC tumor, cancer stem cells (CSCs) are responsible for tumor maintenance and progression and may contribute to resistance to standard HCC treatments. Previously, we characterized CD133⁺ cells as CSCs in primary HCC and identified chromenopyrimidinone (CPO) as a novel therapeutic for the effective treatment of CD133⁺ HCC. However, the biological function and molecular mechanism of CD133 remain unclear. Epigenetic alterations of CSCs have impacts on tumor initiation, progression, and therapeutic response. Here, we found that pharmacological and genetic depletion of CD133 in HCC attenuated the activity of DNA methyltransferases via control of DNMT3B stabilization. Genes were ranked by degree of promoter hypo/hyper methylation and significantly differential expression to create an "epigenetically activated by CPO" ranked genes list. Through this epigenetic analysis, we found that CPO treatment altered DNA methylation-mediated oncogenic signaling in HCCs. Specifically, CPO treatment inhibited Adenylyl cyclase-associated protein 1 (CAP1) expression, thereby reducing FAK/ERK activity and EMT-related proteins in HCC. Moreover, CPO improved the efficacy of sorafenib by inhibiting CAP1 expression and FAK/ERK activation in sorafenib-resistant HCC. These novel mechanistic insights may ultimately open up avenues for strategies targeting DNA methylation in liver cancer stem cells and provides novel therapeutic function of CPO for the effective treatment of sorafenib-resistant HCC.

BRCA1 mutations in high-grade serous ovarian cancer are associated with proteomic changes in DNA repair, splicing, transcription regulation and signaling

Despite recent advances in the management of BRCA1 mutated high-grade serous ovarian cancer (HGSC), the physiology of these tumors remains poorly understood. Here we provide a comprehensive molecular understanding of the signaling processes that drive HGSC pathogenesis with the addition of valuable ubiquitination profiling, and their dependency on BRCA1 mutation-state directly in patient-derived tissues. Using a multilayered proteomic approach, we show the tight coordination between the ubiquitination and phosphorylation regulatory layers and their role in key cellular processes related to BRCA1-dependent HGSC pathogenesis. In addition, we identify key bridging proteins, kinase activity, and post-translational modifications responsible for molding distinct cancer phenotypes, thus providing new opportunities for therapeutic intervention, and ultimately advance towards a more personalized patient care.

Fluorescent reflector and image-processing-based D2D beam-steering system for V2V applications

Device-to-device (D2D) communication that delivers a dedicated channel with low latency and high spectral efficiency has been considered an essential solution for vehicle-to-vehicle (V2V) communication. To achieve such D2D-V2V communication, the beam-steering technique using optical wavelengths can be an attractive candidate due to the advanced optical wireless technologies for point-to-point applications. Recently, there has been research on high-performance optical beam-steering techniques based on microelectromechanical systems mirrors and spatial light modulators in quasi-static indoor environments. Due to the optomechanical complexity, size, and cost, however, their suitability for D2D-V2V applications is problematic. In this work, a cost-effective optical beam-steering system based on a fluorescent reflector and stereo vision for D2D-V2V is introduced. Proof-of-concept demonstration using off-the-shelf devices and components shows that the proposed system can support +-30-deg field of view with a data rate of 300 Mb/s.

AdipoRon: A Novel Insulin Sensitizer in Various Complications and the Underlying Mechanisms: A Review

BACKGROUND

AdipoRon is the first synthetic analog of endogenous adiponectin, an adipose tissue-derived hormone. AdipoRon possesses pharmacological properties similar to adiponectin and its ability to bind and activate the adipoR1 and adipoR2 receptors makes it a suitable candidate for the treatment of a multitude of disorders.

OBJECTIVE

In the present review, an attempt was made to compile and discuss the efficacy of adipoRon against various disorders.

RESULTS

AdipoRon is a drug that acts not only in metabolic diseases but in other conditions unrelated to energy metabolism. It is well- reported that adipoRon exhibits strong anti-obesity, anti-diabetic, anticancer, anti-depressant, anti-ischemic, anti-hypertrophic properties and also improves conditions like post-traumatic stress disorder, anxiety, and systemic sclerosis.

CONCLUSION

A lot is known about its effects in experimental systems, but the translation of this knowledge to the clinic requires studies which, for many of the potential target conditions, have yet to be carried out. The beneficial effects of AdipoRon in novel clinical conditions will suggest an underlying pathophysiological role of adiponectin and its receptors in previously unsuspected settings.

CAPt'n of Actin Dynamics: Recent Advances in the Molecular, Developmental and Physiological Functions of Cyclase-Associated Protein (CAP)

Cyclase-associated protein (CAP) has been discovered three decades ago in budding yeast as a protein that associates with the cyclic adenosine monophosphate (cAMP)-producing adenylyl cyclase and that suppresses a hyperactive RAS2 variant. Since that time, CAP has been identified in all eukaryotic species examined and it became evident that the activity in RAS-cAMP signaling is restricted to a limited number of species. Instead, its actin binding activity is conserved among eukaryotes and actin cytoskeleton regulation emerged as its primary function. However, for many years, the molecular functions as well as the developmental and physiological relevance of CAP remained unknown. In the present article, we will compile important recent progress on its molecular functions that identified CAP as a novel key regulator of actin dynamics, i.e., the spatiotemporally controlled assembly and disassembly of actin filaments (F-actin). These studies unraveled a cooperation with ADF/Cofilin and Twinfilin in F-actin disassembly, a nucleotide exchange activity on globular actin monomers (G-actin) that is required for F-actin assembly and an inhibitory function towards the F-actin assembly factor INF2. Moreover, by focusing on selected model organisms, we will review current literature on its developmental and physiological functions, and we will present studies implicating CAP in human pathologies. Together, this review article summarizes and discusses recent achievements in understanding the molecular, developmental and physiological functions of CAP, which led this protein emerge as a novel CAPt'n of actin dynamics.

Dynamic Phosphorylation and Dephosphorylation of Cyclase-Associated Protein 1 by Antagonistic Signaling through Cyclin-Dependent Kinase 5 and cAMP Are Critical for the Protein Functions in Actin Filament Disassembly and Cell Adhesion

Cyclase-associated protein 1 (CAP1) is a conserved actin-regulating protein that enhances actin filament dynamics and also regulates adhesion in mammalian cells. We previously found that phosphorylation at the Ser307/Ser309 tandem site controls its association with cofilin and actin and is important for CAP1 to regulate the actin cytoskeleton. Here, we report that transient Ser307/Ser309 phosphorylation is required for CAP1 function in both actin filament disassembly and cell adhesion. Both the phosphomimetic and the nonphosphorylatable CAP1 mutant, which resist transition between phosphorylated and dephosphorylated forms, had defects in rescuing the reduced rate of actin filament disassembly in the CAP1 knockdown HeLa cells. The phosphorylation mutants also had defects in alleviating the elevated focal adhesion kinase (FAK) activity and the enhanced focal adhesions in the knockdown cells. In dissecting further phosphoregulatory cell signals for CAP1, we found that cyclin-dependent kinase 5 (CDK5) phosphorylates both Ser307 and Ser309 residues, whereas cAMP signaling induces dephosphorylation at the tandem site, through its effectors protein kinase A (PKA) and exchange proteins directly activated by cAMP (Epac). No evidence supports an involvement of activated protein phosphatase in executing the dephosphorylation downstream from cAMP, whereas preventing CAP1 from accessing its kinase CDK5 appears to underlie CAP1 dephosphorylation induced by cAMP. Therefore, this study provides direct cellular evidence that transient phosphorylation is required for CAP1 functions in both actin filament turnover and adhesion, and the novel mechanistic insights substantially extend our knowledge of the cell signals that function in concert to regulate CAP1 by facilitating its transient phosphorylation.

Mechanism of synergistic actin filament pointed end depolymerization by cyclase-associated protein and cofilin

The ability of cells to generate forces through actin filament turnover was an early adaptation in evolution. While much is known about how actin filaments grow, mechanisms of their disassembly are incompletely understood. The best-characterized actin disassembly factors are the cofilin family proteins, which increase cytoskeletal dynamics by severing actin filaments. However, the mechanism by which severed actin filaments are recycled back to monomeric form has remained enigmatic. We report that cyclase-associated-protein (CAP) works in synergy with cofilin to accelerate actin filament depolymerization by nearly 100-fold. Structural work uncovers the molecular mechanism by which CAP interacts with actin filament pointed end to destabilize the interface between terminal actin subunits, and subsequently recycles the newly-depolymerized actin monomer for the next round of filament assembly. These findings establish CAP as a molecular machine promoting rapid actin filament depolymerization and monomer recycling, and explain why CAP is critical for actin-dependent processes in all eukaryotes.

The cofilin family proteins are actin disassembly factors but the disassembly mechanism is poorly understood. Here authors show that cyclase-associated-protein (CAP) works in synergy with cofilin to accelerate actin filament depolymerization by nearly 100-fold and reveal how CAP destabilizes the interface between terminal actin subunits.

The Cytoskeletal Protein Cyclase-Associated Protein 1 (CAP1) in Breast Cancer: Context-Dependent Roles in Both the Invasiveness and Proliferation of Cancer Cells and Underlying Cell Signals

As a conserved actin-regulating protein, CAP (adenylyl Cyclase-Associated Protein) functions to facilitate the rearrangement of the actin cytoskeleton. The ubiquitously expressed isoform CAP1 drives mammalian cell migration, and accordingly, most studies on the involvement of CAP1 in human cancers have largely been based on the rationale that up-regulated CAP1 will stimulate cancer cell migration and invasiveness. While findings from some studies reported so far support this case, lines of evidence largely from our recent studies point to a more complex and profound role for CAP1 in the invasiveness of cancer cells, where the potential activation of cell adhesion signaling is believed to play a key role. Moreover, CAP1 was also found to control proliferation in breast cancer cells, through the regulation of ERK (External signal-Regulated Kinase). Alterations in the activities of FAK (Focal Adhesion Kinase) and ERK from CAP1 depletion that are consistent to the opposite adhesion and proliferation phenotypes were detected in the metastatic and non-metastatic breast cancer cells. In this review, we begin with the overview of the literature on CAP, by highlighting the molecular functions of mammalian CAP1 in regulating the actin cytoskeleton and cell adhesion. We will next discuss the role of the FAK/ERK axis, and possibly Rap1, in mediating CAP1 signals to control breast cancer cell adhesion, invasiveness, and proliferation, largely based on our latest findings. Finally, we will discuss the relevance of these novel mechanistic insights to ultimately realizing the translational potential of CAP1 in targeted therapeutics for breast cancer.