Reviewing the role of P2Y receptors in specific gastrointestinal cancers

Role and recent progress of P2Y12 receptor in cancer development

P2Y12 receptor (P2Y12R) is an adenosine-activated G protein-coupled receptor (GPCR) that plays a central role in platelet function, hemostasis, and thrombosis. P2Y12R activation can promote platelet aggregation and adhesion to cancer cells, promote tumor angiogenesis, and affect the tumor immune microenvironment (TIME) and tumor drug resistance, which is conducive to the progression of cancers. Meanwhile, P2Y12R inhibitors can inhibit this effect, suggesting that P2Y12R may be a potential therapeutic target for cancer. P2Y12R is involved in cancer development and metastasis, while P2Y12R inhibitors are effective in inhibiting cancer. However, a new study suggests that long-term use of P2Y12R inhibitors may increase the risk of cancer and the mechanism remains to be explored. In this paper, we reviewed the structural and functional characteristics of P2Y12R and its role in cancer. We explored the role of P2Y12R inhibitors in different tumors and the latest advances by summarizing the basic and clinical studies on the effects of P2Y12R inhibitors on tumors.

The functional role of P2 purinergic receptors in the progression of gastric cancer

Studies have confirmed that P2 purinergic receptors (P2X receptors and P2Y receptors) expressed in gastric cancer (GC) cells and GC tissues and correlates with their function. Endogenous nucleotides including ATP, ADP, UTP, and UDP, as P2 purinergic receptors activators, participate in P2 purinergic signal transduction pathway. These activated P2 purinergic receptors regulate the progression of GC mainly by mediating ion channels and intracellular signal cascades. It is worth noting that there is a difference in the expression of P2 purinergic receptors in GC, which may play different roles in the progression of GC as a tumor promoting factor or a tumor suppressor factor. Among them, P2 × 7, P2Y2 and P2Y6 receptors have certain clinical significance in patients with GC and may be used as biological molecular markers for the prediction of patients with GC. Therefore, in this paper, we discuss the functional role of nucleotide / P2 purinergic receptors signal axis in regulating the progression of GC and that these P2 purinergic receptors may be used as potential molecular targets for the prevention and treatment of GC.

P2 purinergic receptors regulate the progression of colorectal cancer

More and more studies have revealed that P2 purinergic receptors play a key role in the progression of colorectal cancer (CRC). P2X and P2Y purinergic receptors can be used as promoters and regulators of CRC and play a dual role in the progression of CRC. CRC microenvironment is rich in ATP and its cleavage products (ADP, AMP, Ado), which act as activators of P2X and P2Y purinergic receptors. The activation of P2X and P2Y purinergic receptors regulates the progression of CRC mainly by regulating the function of immune cells and mediating different signal pathways. In this paper, we focus on the specific mechanisms and functional roles of P2X7, P2Y12, and P2Y2 receptors in the growth and progression of CRC. The antagonistic effects of these selective antagonists of P2X purinergic receptors on the growth, invasion, and metastasis of CRC were further discussed. Moreover, different studies have reported that P2X7 receptor can be used as an effective predictor of patients with CRC. All these indicate that P2 purinergic receptors are a key regulator of CRC. Therefore, antagonizing P2 purinergic receptors may be an innovative treatment for CRC.

Nucleotide metabolism in the regulation of tumor microenvironment and immune cell function

Nucleotide metabolism plays a crucial role in the regulation of the tumor microenvironment (TME) and immune cell function. In the TME, limited availability of nucleotide precursors due to increased consumption by tumor cells and T cells affects both tumor development and immune function. Metabolic reprogramming in tumor cells favors pathways supporting growth and proliferation, including nucleotide synthesis. Additionally, extracellular nucleotides, such as ATP and adenosine, exhibit dual roles in modulating immune function and tumor cell survival. ATP stimulates antitumor immunity by activating purinergic receptors, while adenosine acts as a potent immunosuppressor. Targeting nucleotide metabolism in the TME holds immense promise for cancer therapy. Understanding the intricate relationship between nucleotide metabolism, the TME, and immune responses will pave the way for innovative therapeutic interventions.

Ligand-dependent intracellular trafficking of the G protein-coupled P2Y6 receptor

Endosomal trafficking is intricately linked to G protein-coupled receptors (GPCR) fate and signaling. Extracellular uridine diphosphate (UDP) acts as a signaling molecule by selectively activating the GPCR P2Y₆. Despite the recent interest for this receptor in pathologies, such as gastrointestinal and neurological diseases, there is sparse information on the endosomal trafficking of P2Y₆ receptors in response to its endogenous agonist UDP and synthetic selective agonist 5-iodo-UDP (MRS2693). Confocal microscopy and cell surface ELISA revealed delayed internalization kinetics in response to MRS2693 vs. UDP stimulation in AD293 and HCT116 cells expressing human P2Y₆. Interestingly, UDP induced clathrin-dependent P2Y₆ internalization, whereas receptor stimulation by MRS2693 endocytosis appeared to be associated with a caveolin-dependent mechanism. Internalized P2Y₆ was associated with Rab4, 5, and 7 positive vesicles independent of the agonist. We have measured a higher frequency of receptor expression co-occurrence with Rab11-vesicles, the trans-Golgi network, and lysosomes in response to MRS2693. Interestingly, a higher agonist concentration reversed the delayed P2Y₆ internalization and recycling kinetics in the presence of MRS2693 stimulation without changing its caveolin-dependent internalization. This work showed a ligand-dependent effect affecting the P2Y₆ receptor internalization and endosomal trafficking. These findings could guide the development of bias ligands that could influence P2Y₆ signaling.

Activation of hypermethylated P2RY1 mitigates gastric cancer by promoting apoptosis and inhibiting proliferation

The P2RY1 receptor is known to cause cancer by activating the ERK signal pathway, and its DNA methylation status and corresponding regulatory mechanism remain unknown. This study used the DNA methylation chip to profile the genome-wide DNA methylation level in gastric cancer tissues. The proliferation and apoptosis of the SGC7901 gastric cancer cell line were determined after treatment with a selective P2RY1 receptor agonist, MRS2365. The promoter region of P2RY1 was found to be highly methylated with four hypermethylated sites (|Δβ value| > 0.2) in diffuse gastric cancer and was validated by bioinformatics analysis in the TCGA database. Also, immunohistochemical staining data obtained from the HPA database demonstrated the downregulated expression of proteins encoded by P2RY1 in stomach cancer tissue. The analysis of MRS2365-treated cells by annexin V/propidium iodide staining and caspase-3 activity assays indicated the induction of apoptosis in SGC7901 cells. The P2RY1 receptor activation in human SGC7901 gastric cancer cells via the MRS2365 agonist induced apoptosis and reduced cell growth. High DNA methylation in the promoter region of P2RY1 might have contributed to the reduced expression of P2RY1's mRNA, which was likely responsible for the "aggressive" nature of the diffuse gastric cancer.

The P2 purinoceptors in prostate cancer

P2 purinoceptors are composed of ligand-gated ion channel type (P2X receptor) and G protein-coupled metabolite type (P2Y receptor). Both these receptors have played important roles in the prostate cancer microenvironment in recent years. P2X and P2Y receptors can contribute to prostate cancer's growth and invasiveness. However, the comprehensive mechanisms have yet to be identified. By summarizing the relevant studies, we believe that P2X and P2Y receptors play a dual role in cancer cell growth depending on the prostate cancer microenvironment and different downstream signalling pathways. We also summarized how different signalling pathways contribute to tumor invasiveness and metastasis through P2X and P2Y receptors, focusing on understanding the specific mechanisms led by P2X4, P2X7, and P2Y2. Statins may reduce and prevent tumor progression through P2X7 so that P2X purinergic receptors may have clinical implications in the management of prostate cancer. Furthermore, P2X7 receptors can aid in the early detection of prostate cancer. We hope that this review will provide new insights for future mechanistic and clinical investigations into the role of P2 purinergic receptors in prostate cancer.

An Update of G-Protein-Coupled Receptor Signaling and Its Deregulation in Gastric Carcinogenesis

G-protein-coupled receptors (GPCRs) belong to a cell surface receptor superfamily responding to a wide range of external signals. The binding of extracellular ligands to GPCRs activates a heterotrimeric G protein and triggers the production of numerous secondary messengers, which transduce the extracellular signals into cellular responses. GPCR signaling is crucial and imperative for maintaining normal tissue homeostasis. High-throughput sequencing analyses revealed the occurrence of the genetic aberrations of GPCRs and G proteins in multiple malignancies. The altered GPCRs/G proteins serve as valuable biomarkers for early diagnosis, prognostic prediction, and pharmacological targets. Furthermore, the dysregulation of GPCR signaling contributes to tumor initiation and development. In this review, we have summarized the research progress of GPCRs and highlighted their mechanisms in gastric cancer (GC). The aberrant activation of GPCRs promotes GC cell proliferation and metastasis, remodels the tumor microenvironment, and boosts immune escape. Through deep investigation, novel therapeutic strategies for targeting GPCR activation have been developed, and the final aim is to eliminate GPCR-driven gastric carcinogenesis.

P2RY13 Exacerbates Intestinal Inflammation by Damaging the Intestinal Mucosal Barrier via Activating IL-6/STAT3 Pathway

The pathogenesis of ulcerative colitis (UC) is unclear, while genetic factors have been confirmed to play an important role in its development. P2RY13 is a G protein-coupled receptor (GPCRs), which are involved in the pathogenesis of inflammation and immune disorders. According to GEO database analysis, we first observed that the expression of P2Y13 was increased in UC patients. Therefore, we sought to determine the role of P2Y13 in the development of colitis. Our data showed that P2RY13 was highly expressed in the inflamed intestinal tissues of UC patients. In mice, pharmacological antagonism of P2Y13 can significantly attenuate the intestinal mucosal barrier disruption. In LPS-induced NCM460 cell, knockdown or pharmacological inhibition of P2RY13 increased the expression of intestinal tight junction protein and reduced apoptosis. In addition, we found that the effect of P2Y13 on colitis is related to the activation of the IL-6/STAT3 pathway. Activation of P2Y13 increases IL-6 expression and promotes STAT3 phosphorylation and nuclear transport. Deletion of the STAT3 gene in the intestinal epithelial cells of mice significantly mitigated the exacerbation of colitis due to P2Y13 activation. Thus, P2Y13 can aggravate intestinal mucosal barrier destruction by activating the IL-6/STAT3 pathway. P2Y13 might be a potential drug target for UC.

GPCR genes as a predictor of glioma severity and clinical outcome

OBJECTIVE

To undertake a comprehensive analysis of the differential expression of the G protein-coupled receptor (GPCR) genes in order to construct a GPCR gene signature for human glioma prognosis.

METHODS

This current study investigated several glioma transcriptomic datasets and identified the GPCR genes potentially associated with glioma severity.

RESULTS

A gene signature comprising 13 GPCR genes (nine upregulated and four downregulated genes in high-grade glioma) was developed. The predictive power of the 13-gene signature was tested in two validation cohorts and a strong positive correlation (Spearman's rank correlation test: ρ = 0.649 for the Validation1 cohort; ρ = 0.693 for the Validation2 cohort) was observed between the glioma grade and 13-gene based severity score in both cohorts. The 13-gene signature was also predictive of glioma prognosis based on Kaplan-Meier survival curve analyses and Cox proportional hazard regression analysis in four cohorts of patients with glioma.

CONCLUSIONS

Knowledge of GPCR gene expression in glioma may help researchers gain a better understanding of the pathogenesis of high-grade glioma. Further studies are needed to validate the association between these GPCR genes and glioma pathogenesis.

Novel possibility for cutaneous melanoma treatment by means of rosmarinic acid action on purinergic signaling

Cancer cases have increased significantly in Brazil and worldwide, with cutaneous melanoma (CM) being responsible for nearly 57,000 deaths in the world. Thus, this review article aims at exploring and proposed hypotheses with respect to the possibility that RA can be a promising and alternative compound to be used as an adjuvant in melanoma treatment, acting on purinergic signaling. The scarcity of articles evidencing the action of this compound in this signaling pathway requires further studies. Considering diverse evidence found in the literature, we hypothesize that RA can be an effective candidate for the treatment of CM acting as a modulating molecule of purinergic cellular pathway through P2X7 blocking, mitigating the Warburg effect, and as antagonic molecule of the P2Y12 receptor, reducing the formation of adhesive molecules that prevent adherence in tumor cells. In this way, our proposals for CM treatment based on targeting purinergic signaling permeate the integral practice, going from intracell to extracell. Undoubtedly, much is still to be discovered and elucidated about this promising compound, this paper being an interesting work baseline to support more research studies.

Extracellular ATP Induced S-Phase Cell Cycle Arrest via P2Y Receptor-Activated ERK Signaling in Poorly Differentiated Oral Squamous Cell Carcinoma SAS Cells

Extracellular ATP in the tumor microenvironment exhibits either pro- or antitumor effect via interaction with P2Y receptors, but the intracellular signaling and functional roles of P2Y receptors in oral squamous cell carcinoma (OSCC) are unclear. We aimed to study the effect of ATP on OSCC cell lines and the potential mechanisms involved. Through GEPIA dataset analysis, high expression levels of mRNA encoding P2Y receptors, the ATP-induced G protein-coupled receptors, were associated with better overall patient survival in head and neck squamous cell carcinoma. qPCR analysis showed that the poorly differentiated OSCC SAS cell line, had higher P2RY1 expression level compared to the well-differentiated H103 and H376 cell lines. Western blotting and flow cytometry analyses revealed that ATP phosphorylated ERK and elevated intracellular calcium signaling in all tested cell lines. A significant S-phase cell cycle arrest was observed in SAS, and preincubation with the MEK inhibitor PD0325901 reversed the ATP-induced S-phase arrest. We further demonstrated that ATP induced a slight reduction in cell count and colony formation yet significant apoptosis in SAS. Overall, we postulate that the ATP-induced S-phase arrest effect in SAS cells may be regulated through P2Y receptor-mediated ERK signaling, thus suggesting a potential antitumor effect of ATP via interaction with its distinct profile of P2Y receptors.

Expression Pattern of Purinergic Signaling Components in Colorectal Cancer Cells and Differential Cellular Outcomes Induced by Extracellular ATP and Adenosine

The purine nucleotide adenosine triphosphate (ATP) is known for its fundamental role in cellular bioenergetics. However, in the last decades, different works have described emerging functions for ATP, such as that of a danger signaling molecule acting in the extracellular space on both tumor and stromal compartments. Beside its role in immune cell signaling, several studies have shown that high concentrations of extracellular ATP can directly or indirectly act on cancer cells. Accordingly, it has been reported that purinergic receptors are widely expressed in tumor cells. However, their expression pattern is often associated with contradictory cellular outcomes. In this work, we first investigated gene expression profiles through "RNA-Sequencing" (RNA Seq) technology in four colorectal cancer (CRC) cell lines (HT29, LS513, LS174T, HCT116). Our results demonstrate that CRC cells mostly express the A2B, P2X4, P2Y1, P2Y2 and P2Y11 purinergic receptors. Among these, the P2Y1 and P2Y2 coding genes are markedly overexpressed in all CRC cells compared to the HCEC-1CT normal-like colonic cells. We then explored the cellular outcomes induced by extracellular ATP and adenosine. Our results show that in terms of cell death induction extracellular ATP is consistently more active than adenosine against CRC, while neither compound affected normal-like colonic cell survival. Intriguingly, while for the P2Y2 receptor pharmacological inhibition completely abolished the rise in cytoplasmic Ca²⁺ observed after ATP exposure in all CRC cell lines, Ca²⁺ mobilization only impacted the cellular outcome for HT29. In contrast, non-selective phosphodiesterase inhibition completely abolished the effects of extracellular ATP on CRC cells, suggesting that cAMP and/or cGMP levels might determine cellular outcome. Altogether, our study provides novel insights into the characterization of purinergic signaling in CRC.

P2RY12-Inhibitors Reduce Cancer-Associated Thrombosis and Tumor Growth in Pancreatic Cancers

Platelet function can be modified by cancer cells to support tumor growth, causing alterations in the delicate hemostatic equilibrium. Cancer-cell and platelet interactions are one of the main pillars of Trousseau’s syndrome: a paraneoplastic syndrome with recurring and migrating episodes of thrombophlebitis. Altogether, this leads to a four-fold risk of thrombotic events in cancer patients, which in turn, portend a poor prognosis. We previously demonstrated that anti-P2RY12 drugs inhibit cancer-associated-thrombosis and formation of tumor metastasis in pancreatic cancer models. Here, we aimed to (1) compare the effects of aspirin and clopidogrel on pancreatic cancer prevention, (2) characterize the effects of clopidogrel (platelet P2RY12 inhibitor) on cancer-associated thrombosis and cancer growth in vivo, (3) determine the effect of P2RY12 across different digestive-tract cancers in vitro, and (4) analyze the expression pattern of P2RY12 in two different cancer types affecting the digestive system. Clopidogrel treatment resulted in better survival rates with smaller primary tumors and less metastasis than aspirin treatment. Clopidogrel was also more effective than aspirin at dissolving spontaneous endogenous thrombi in our orthotopic advanced cancer mouse model. P2RY12 expression gives pancreatic adenocarcinomas proliferative advantages. In conclusion, we propose the hypothesis that clopidogrel should be further studied to target and prevent Trousseau’s syndrome; as well as diminish cancer growth and spread. However, more studies are required to determine the implicated pathways and effects of these drugs on cancer development.

Evaluation of tumor microenvironmental immune regulation and prognostic in lung adenocarcinoma from the perspective of purinergic receptor P2Y13

Tumor-infiltrating immune cells (TICs) can serve as an important indicator to evaluate the prognosis and therapeutic response in lung adenocarcinoma (LUAD). The identification of mutated genes that can affect the abundance of TICs and prognosis has practical implications. In the presented study, tumor microenvironment (TME) scoring was performed by the ESTIMATE scoring system on 598 RNA transcripts selected from the TCGA database to determine the proportions of immune cells and stromal cells. The infiltration difference of TICs in LUAD samples was obtained by CIBERSORT. The 'immuneeconv' R software package, which integrates six latest algorithms, including TIMER, xCell, MCP-counter, CIBERSORT, EPIC and quanTIseq were used to verify the correlation between purinergic receptor P2Y13 (P2RY13) and immune cells. Based on RNA sequencing analysis of the Lewis lung cancer-bearing model in C57BL/6 mice and immunohistochemistry (IHC) of human LUAD tissues, the expression of P2RY13 and associated pathways were verified. It was shown that differentially expressed genes (DEGs) obtained by interactive analysis based on Immunescore and Stromalscore were significantly enriched in immune-related pathways. The expression of P2RY13 was significantly associated with prognosis and clinicopathological characteristics of LUAD patients. More importantly, this gene played an important role in maintaining the immune dominant environment and changing the regulation of TICs. P2RY13 expression was positively correlated with the infiltration of dendritic cells (DCs) in various of tumor tissues as validated by the PanglaoDB scRNA-seq database. Therefore, P2RY13 is expected to be a potential biomarker for predicting TME and the prognosis of LUAD after verification.

Purinergic P2Y2 and P2X4 Receptors Are Involved in the Epithelial-Mesenchymal Transition and Metastatic Potential of Gastric Cancer Derived Cell Lines

Gastric cancer (GC) is a major health concern worldwide, presenting a complex pathophysiology that has hindered many therapeutic efforts so far. In this context, purinergic signaling emerges as a promising pathway for intervention due to its known role in cancer cell proliferation and migration. In this work, we explored in more detail the role of purinergic signaling in GC with several experimental approaches. First, we measured extracellular ATP concentrations on GC-derived cell lines (AGS, MKN-45, and MKN-74), finding higher levels of extracellular ATP than those obtained for the non-tumoral gastric cell line GES-1. Next, we established the P2Y2 and P2X4 receptors (P2Y2R and P2X4R) expression profile on these cells and evaluated their role on cell proliferation and migration after applying overexpression and knockdown strategies. In general, a P2Y2R overexpression and P2X4R downregulation pattern were observed on GC cell lines, and when these patterns were modified, concomitant changes in cell viability were observed. These modifications on gene expression also modified transepithelial electrical resistance (TEER), showing that higher P2Y2R levels decreased TEER, and high P2X4R expression had the opposite effect, suggesting that P2Y2R and P2X4R activation could promote and suppress epithelial-mesenchymal transition (EMT), respectively. These effects were confirmed after treating AGS cells with UTP, a P2Y2R-agonist that modified the expression patterns towards mesenchymal markers. To further characterize the effects of P2Y2R activation on EMT, we used cDNA microarrays and observed that UTP induced important transcriptional changes on several cell processes like cell proliferation induction, apoptosis inhibition, cell differentiation induction, and cell adhesion reduction. These results suggest that purinergic signaling plays a complex role in GC pathophysiology, and changes in purinergic balance can trigger tumorigenesis in non-tumoral gastric cells.

From purines to purinergic signalling: molecular functions and human diseases

Purines and their derivatives, most notably adenosine and ATP, are the key molecules controlling intracellular energy homoeostasis and nucleotide synthesis. Besides, these purines support, as chemical messengers, purinergic transmission throughout tissues and species. Purines act as endogenous ligands that bind to and activate plasmalemmal purinoceptors, which mediate extracellular communication referred to as "purinergic signalling". Purinergic signalling is cross-linked with other transmitter networks to coordinate numerous aspects of cell behaviour such as proliferation, differentiation, migration, apoptosis and other physiological processes critical for the proper function of organisms. Pathological deregulation of purinergic signalling contributes to various diseases including neurodegeneration, rheumatic immune diseases, inflammation, and cancer. Particularly, gout is one of the most prevalent purine-related disease caused by purine metabolism disorder and consequent hyperuricemia. Compelling evidence indicates that purinoceptors are potential therapeutic targets, with specific purinergic agonists and antagonists demonstrating prominent therapeutic potential. Furthermore, dietary and herbal interventions help to restore and balance purine metabolism, thus addressing the importance of a healthy lifestyle in the prevention and relief of human disorders. Profound understanding of molecular mechanisms of purinergic signalling provides new and exciting insights into the treatment of human diseases.

[A Review of the State of Purinergic Signaling and Psychological Stress]

Purinergic signaling is involved in multiple physiological and pathological processes. Psychological stress, as an inharmonious state in response to stressors, is closely related to the function or dysfunction of purinergic signaling. Abnormal expression of ATP interceptors caused by stress leads to psychological stress-related diseases, such as anxiety, depression, post-traumatic stress disorder and schizophrenia. Recent studies demonstrate that a complex network of purinergic signaling (such as ATP, adenosine and P2X2R, P2X3R, P2X4R, P2X7R, A1R, A2AR) plays a key role in psychological stress, but the specific mechanism remains to be further studied. And few studies focus on the application of ATP real-time detecting to psychological stress animal models, so the specific biological role of ATP in the process of stress is still unknown. This review will summarize the relationship between purinergic signaling and psychological stress and propose to apply the duplicate ATP real-time detection technology and purinergic compounds on psychological stress research in order to provide novel potential targets for the treatment of stress-related diseases.

P2Y12 shRNA normalizes inflammatory dysfunctional hepatic glucokinase activity in type 2 diabetic rats

The celiac ganglion projects its postganglionic (including purinergic) fibers to the liver. P2Y12 receptor is one of the P2Y family members. We found that the expression levels of P2Y12 receptor in both celiac ganglia and liver were increased in type 2 diabetes mellitus (T2DM) rats which also displayed an enhanced activity of celiac sympathetic nerve discharge (SND). In addition, a marked decrease of hepatic glucokinase (GK) expression was accompanied by reduced hepatic glycogen synthesis in T2DM rats, whereas meanwhile the levels of NLRP3, active caspase-1, NF-κB, and interleukin-1β were elevated. All these abnormal alterations could be largely reversed after treatment of short hairpin RNA (shRNA) targeting P2Y12. Our results indicate that the silence of P2Y12 by shRNA may effectively correct the anomalous activity of celiac SND and improve the dysfunctional hepatic glucokinase by counteracting hepatocyte inflammation and likely pyroptosis due to activated NLRP3 inflammasome and caspase-1 signaling, thereby attenuating hyperglycemia in T2DM rats.

The P2Y6 receptor signals through Gαq /Ca2+ /PKCα and Gα13 /ROCK pathways to drive the formation of membrane protrusions and dictate cell migration

Cell migration is a ubiquitous process necessary to maintain and restore tissue functions. However, in cancer, cell migration leads to metastasis development and thus worsens the prognosis. Although the mechanism of cell migration is well understood, the identification of new targets modulating cell migration and deciphering their signaling events could lead to new therapies to restore tissue functions in diseases, such as inflammatory bowel disease, or to block metastatic development in different forms of cancer. Previous research has identified the G-protein-coupled P2Y₆ receptor as an innovative target that could dictate cell migration under normal and pathological conditions. Surprisingly, there is little information on the cellular events triggered by activated P2Y₆ during cell migration. Here, we demonstrated that P2Y₆ activation stimulated A549 human lung cancer cells and Caco-2 colorectal cancer cell migration. Activated P2Y₆ increased the number of filopodia and focal adhesions; two migratory structures required for cell migration. The generation of these structures involved Gα_q /calcium/protein kinases C (PKC) and Gα₁₃ /RHO-associated protein kinase-dependent pathways that dictate the formation of the migratory structures. These pathways led to the stabilization of the actin cytoskeleton through a PKC-dependent phosphorylation of cofilin. These results support the idea that the P2Y₆ receptor represents a target of interest to modulate cell migration and revealed an intricate dialogue between two Gα-protein signaling pathways.

Quinolinate Phosphoribosyltransferase Promotes Invasiveness of Breast Cancer Through Myosin Light Chain Phosphorylation

Perturbed Nicotinamide adenine dinucleotide (NAD⁺) homeostasis is involved in cancer progression and metastasis. Quinolinate phosphoribosyltransferase (QPRT) is the rate-limiting enzyme in the kynurenine pathway participating in NAD⁺ generation. In this study, we demonstrated that QPRT expression was upregulated in invasive breast cancer and spontaneous mammary tumors from MMTV-PyVT transgenic mice. Knockdown of QPRT expression inhibited breast cancer cell migration and invasion. Consistently, ectopic expression of QPRT promoted cell migration and invasion in breast cancer cells. Treatment with QPRT inhibitor (phthalic acid) or P2Y₁₁ antagonist (NF340) could reverse the QPRT-induced invasiveness and phosphorylation of myosin light chain. Similar reversibility could be observed following treatment with Rho inhibitor (Y16), ROCK inhibitor (Y27632), PLC inhibitor (U73122), or MLCK inhibitor (ML7). Altogether, these results indicate that QPRT enhanced breast cancer invasiveness probably through purinergic signaling and might be a potential prognostic indicator and therapeutic target in breast cancer.