P2X7 receptor: a critical regulator and potential target for breast cancer

Functional role of P2X7 purinergic receptor in cancer and cancer-related pain

Numerous studies have revealed that the ATP-gated ion channel purinergic 2X7 receptor (P2X7R) plays an important role in tumor progression and the pathogenesis of cancer pain. P2X7R requires activation by extracellular ATP to perform its regulatory role functions. During tumor development or cancer-induced pain, ATP is released from tumor cells or other cells in the tumor microenvironment (such as tumor-associated immune cells), which activates P2X7R, opens ion channels on the cell membrane, affects intracellular molecular metabolism, and regulates the activity of tumor cells. Furthermore, peripheral organs and receptors can be damaged during tumor progression, and P2X7R expression in nerve cells (such as microglia) is significantly upregulated, enhancing sensory afferent information, sensitizing the central nervous system, and inducing or exacerbating pain. These findings reveal that the ATP-P2X7R signaling axis plays a key regulatory role in the pathogenesis of tumors and cancer pain and also has a therapeutic role. Accordingly, in this study, we explored the role of P2X7R in tumors and cancer pain, discussed the pharmacological properties of inhibiting P2X7R activity (such as the use of antagonists) or blocking its expression in the treatment of tumor and cancer pain, and provided an important evidence for the treatment of both in the future.

The impact of the P2X7 receptor on the tumor immune microenvironment and its effects on tumor progression

Cancer is a significant global health concern, and finding effective methods to treat it has been a focus of scientific research. It has been discovered that the growth, invasion, and metastasis of tumors are closely related to the environment in which they exist, known as the tumor microenvironment (TME). The immune response interacting with the tumor occurring within the TME constitutes the tumor immune microenvironment, and the immune response can lead to anti-tumor and pro-tumor outcomes and has shown tremendous potential in immunotherapy. A channel called the P2X7 receptor (P2X7R) has been identified within the TME. It is an ion channel present in various immune cells and tumor cells, and its activation can lead to inflammation, immune responses, angiogenesis, immunogenic cell death, and promotion of tumor development. This article provides an overview of the structure, function, and pharmacological characteristics of P2X7R. We described the concept and components of tumor immune microenvironment and the influence immune components has on tumors. We also outlined the impact of P2X7R regulation and how it affects the development of tumors and summarized the effects of drugs targeting P2X7R on tumor progression, both past and current, assisting researchers in treating tumors using P2X7R as a target.

Low-energy shock waves promote the cisplatin chemosensitivity of human osteosarcoma MNNG/HOS cells via the P2X7/Akt/mTOR pathway

Background

The current dilemma of osteosarcoma treatment is the resistance of chemotherapeutic drugs after long-term usage, which also introduces life-threatening side effects.

Methods and results

To minimize chemoresistance in osteosarcoma patients, the authors applied shock waves (SWs) to human osteosarcoma MNNG/HOS cells, then evaluated the cell viability and extracellular ATP levels, and further investigated the effect of SWs on cisplatin (DDP) cytotoxicity in MNNG/HOS cells. The authors' results showed that 400 SW pulses at 0.21 mJ/mm2 exhibited little influence on the MNNG/HOS cell viability. In addition, this SW condition significantly promoted the extracellular ATP release in MNNG/HOS cells. Importantly, low-energy SWs obviously increased Akt and mammalian target of rapamycin (mTOR) phosphorylation and activation in MNNG/HOS cells, which could be partially reversed in the presence of P2X7 siRNA. The authors also found that low-energy SWs strongly increased the DDP sensitivity of MNNG/HOS cells in the absence of P2X7.

Conclusions

For the first time, the authors found that SW therapy reduced the DDP resistance of MNNG/HOS osteosarcoma cells when the ATP receptor P2X7 was downregulated. SW therapy may provide a novel treatment strategy for chemoresistant human osteosarcoma.

The role of the purinergic ligand-gated ion channel 7 receptor in common digestive system cancers

The incidence of digestive malignancies has increased in recent years, including colorectal cancer (CRC), hepatocellular carcinoma (HCC) and pancreatic cancer. Advanced stages of these cancers are prone to metastasis, which seriously reduce the standard of living of patients and lead to decline in the survival rate of patients. So far there are no good specific drugs to stop this phenomenon. It is very important and urgent to find new biomarkers and therapeutic targets. Purinergic ligand-gated ion channel 7 receptor (P2X7R) is ATP-gated and nonselective ion channel receptor involved in many inflammatory processes and cancer progression. P2X7R is present in many cancer cells and promotes or inhibits cancer development through signal transduction. Studies have presented that P2X7R plays a role in the proliferation and migration of digestive system cancers, such as CRC, HCC and pancreatic cancer. Therefore, P2X7R may serve as a biomarker or therapeutic target for digestive system cancers. This paper describes the structure and function of P2X7R, and mainly reviews the research progress on the role of P2X7R in CRC, HCC and pancreatic cancer.

Novel synthesized ionizable lipid for LNP-mediated P2X7siRNA to inhibit migration and induce apoptosis of breast cancer cells

The development of ionizable lipid (IL) was necessary to enable the effective formulation of small interfering RNA (siRNA) to inhibit P2X7 receptors (P2X7R), a key player in tumor proliferation, apoptosis, and metastasis. In this way, the synthesis and utility of IL for enhancing cellular uptake of lipid nanoparticles (LNP) improve the proper delivery of siRNA-LNPs for knockdown overexpression of P2X7R. Therefore, to evaluate the impact of P2X7 knockdown on breast cancer (BC) migration and apoptosis, a branched and synthesized ionizable lipid (SIL) was performed for efficient transfection of LNP with siRNA for targeting P2X7 receptors (siP2X7) in mouse 4T-1 cells. Following synthesis and structural analysis of SIL, excellent characterization of the LNP was achieved (Z-average 126.8 nm, zeta-potential - 12.33, PDI 0.16, and encapsulation efficiency 85.35%). Afterward, the stability of the LNP was evaluated through an analysis of the leftover composition, and toxic concentration values for SIL and siP2X7 were determined. Furthermore, siP2X7-LNP cellular uptake in the formulation was assessed via confocal microscopy. Following determining the optimal dose (45 pmol), wound healing analysis was assessed using scratch assay microscopy, and apoptosis was evaluated using flow cytometry. The use of the innovative branched SIL in the formulation of siP2X7-LNP resulted in significant inhibition of migration and induction of apoptosis in 4T-1 cells due to improved cellular uptake. Subsequently, the innovative SIL represents a critical role in efficiently delivering siRNA against murine triple-negative breast cancer cells (TNBC) using LNP formulation, resulting in significant efficacy.

Elucidating the molecular basis of ATP-induced cell death in breast cancer: Construction of a robust prognostic model

BACKGROUND

Breast cancer is a multifaceted and formidable disease with profound public health implications. Cell demise mechanisms play a pivotal role in breast cancer pathogenesis, with ATP-triggered cell death attracting mounting interest for its unique specificity and potential therapeutic pertinence.

AIM

To investigate the impact of ATP-induced cell death (AICD) on breast cancer, enhancing our understanding of its mechanism.

METHODS

The foundational genes orchestrating AICD mechanisms were extracted from the literature, underpinning the establishment of a prognostic model. Simultaneously, a microRNA (miRNA) prognostic model was constructed that mirrored the gene-based prognostic model. Distinctions between high- and low-risk cohorts within mRNA and miRNA characteristic models were scrutinized, with the aim of delineating common influence mechanisms, substantiated through enrichment analysis and immune infiltration assessment.

RESULTS

The mRNA prognostic model in this study encompassed four specific mRNAs: P2X purinoceptor 4, pannexin 1, caspase 7, and cyclin 2. The miRNA prognostic model integrated four pivotal miRNAs: hsa-miR-615-3p, hsa-miR-519b-3p, hsa-miR-342-3p, and hsa-miR-324-3p. B cells, CD4+ T cells, CD8+ T cells, endothelial cells, and macrophages exhibited inverse correlations with risk scores across all breast cancer subtypes. Furthermore, Kyoto Encyclopedia of Genes and Genomes analysis revealed that genes differentially expressed in response to mRNA risk scores significantly enriched 25 signaling pathways, while miRNA risk scores significantly enriched 29 signaling pathways, with 16 pathways being jointly enriched.

CONCLUSION

Of paramount significance, distinct mRNA and miRNA signature models were devised tailored to AICD, both potentially autonomous prognostic factors. This study's elucidation of the molecular underpinnings of AICD in breast cancer enhances the arsenal of potential therapeutic tools, offering an unparalleled window for innovative interventions. Essentially, this paper reveals the hitherto enigmatic link between AICD and breast cancer, potentially leading to revolutionary progress in personalized oncology.

Ion channel P2X7 receptor in the progression of cancer

P2X7 receptor (P2X7) is a non-selective and ATP-sensitive ligand-gated cation channel. Studies have confirmed that it is expressed in a variety of cells and correlates with their function, frequently in immune cells and tumor cells. We found increased expression of this receptor in many tumor cells, and it has a role in tumor survival and progression. In immune cells, upregulation of the receptor has a double effect on tumor suppression as well as tumor promotion. This review describes the structure of P2X7 and its role in the tumor microenvironment and presents possible mechanisms of P2X7 in tumor invasion and metastasis. Understanding the potential of P2X7 for tumor treatment, we also present several therapeutic agents targeting P2X7 and their mechanisms of action. In conclusion, the study of P2X7 is an important guideline for the use of clinical tumor therapy and may be able to provide a new idea for tumor treatment, but considering the complexity of the biological effects of P2X7, the drugs should be used with caution in clinical practice.

Adenosine triphosphate induced cell death: Mechanisms and implications in cancer biology and therapy

Adenosine triphosphate (ATP) induced cell death (AICD) is a critical cellular process that has garnered substantial scientific interest for its profound relevance to cancer biology and to therapeutic interventions. This comprehensive review unveils the intricate web of AICD mechanisms and their intricate connections with cancer biology. This review offers a comprehensive framework for comprehending the multifaceted role of AICD in the context of cancer. This is achieved by elucidating the dynamic interplay between systemic and cellular ATP homeostasis, deciphering the intricate mechanisms governing AICD, elucidating its intricate involvement in cancer signaling pathways, and scrutinizing validated key genes. Moreover, the exploration of AICD as a potential avenue for cancer treatment underscores its essential role in shaping the future landscape of cancer therapeutics.

PAICS as a potential target for cancer therapy linking purine biosynthesis to cancer progression

Tumor cells are required to undergo metabolic reprogramming for rapid development and progression, and one of the metabolic characteristics of cancer cells is the excessive synthesis and utilization of nucleotides. Abnormally increased nucleotides and their metabolites not only directly accelerate tumor cell progression but also indirectly act on stromal cells in the tumor microenvironment (TME) via a paracrine manner to regulate tumor progression. Purine nucleotides are mainly produced via de novo nucleotide synthesis in tumor cells; therefore, intervening in their synthesis has emerged as a promising strategy in anti-tumor therapy. De novo purine synthesis is a 10-step reaction catalyzed by six enzymes to synthesize inosine 5-monophosphate (IMP) and subsequently synthesize AMP and GMP. Phosphoribosylaminoimidazole carboxylase/phosphori-bosylaminoimidazole succinocarboxamide synthetase (PAICS) is a bifunctional enzyme that catalyzes de novo purine synthesis. Aberrantly elevated PAICS expression in various tumors is associated with poor prognosis. Evidence suggests that PAICS and its catalytic product, N-succinylcarboxamide-5-aminoimidazole ribonucleotide (SAICAR), could inhibit tumor cell apoptosis and promote the growth, epithelial-mesenchymal transition (EMT), invasion, and metastasis by regulating signaling pathways such as pyruvate kinase M2 (PKM2), extracellular signal-related kinases 1 and 2 (ERK1/2), focal adhesion kinase (FAK) and so on. This review summarizes the structure, biological functions and the molecular mechanisms of PAICS in cancer development and discusses its potential to be a target for tumor therapy.

Purine and purinergic receptors in health and disease

Purines and purinergic receptors are widely distributed throughout the human body. Purine molecules within cells play crucial roles in regulating energy metabolism and other cellular processes, while extracellular purines transmit signals through specific purinergic receptors. The ubiquitous purinergic signaling maintains normal neural excitability, digestion and absorption, respiratory movement, and other complex physiological activities, and participates in cell proliferation, differentiation, migration, and death. Pathological dysregulation of purinergic signaling can result in the development of various diseases, including neurodegeneration, inflammatory reactions, and malignant tumors. The dysregulation or dysfunction of purines and purinergic receptors has been demonstrated to be closely associated with tumor progression. Compared with other subtypes of purinergic receptors, the P2X7 receptor (P2X7R) exhibits distinct characteristics (i.e., a low affinity for ATP, dual functionality upon activation, the mediation of ion channels, and nonselective pores formation) and is considered a promising target for antitumor therapy, particularly in patients with poor response to immunotherapy This review summarizes the physiological and pathological significance of purinergic signaling and purinergic receptors, analyzes their complex relationship with tumors, and proposes potential antitumor immunotherapy strategies from tumor P2X7R inhibition, tumor P2X7R overactivation, and host P2X7R activation. This review provides a reference for clinical immunotherapy and mechanism investigation.

The P2X7 Receptor in Oncogenesis and Metastatic Dissemination: New Insights on Vesicular Release and Adenosinergic Crosstalk

The tumor niche is an environment rich in extracellular ATP (eATP) where purinergic receptors have essential roles in different cell subtypes, including cancer, immune, and stromal cells. Here, we give an overview of recent discoveries regarding the role of probably the best-characterized purinergic receptor in the tumor microenvironment: P2X7. We cover the activities of the P2X7 receptor and its human splice variants in solid and liquid cancer proliferation, dissemination, and crosstalk with immune and endothelial cells. Particular attention is paid to the P2X7-dependent release of microvesicles and exosomes, their content, including ATP and miRNAs, and, in general, P2X7-activated mechanisms favoring metastatic spread and niche conditioning. Moreover, the emerging role of P2X7 in influencing the adenosinergic axis, formed by the ectonucleotidases CD39 and CD73 and the adenosine receptor A2A in cancer, is analyzed. Finally, we cover how antitumor therapy responses can be influenced by or can change P2X7 expression and function. This converging evidence suggests that P2X7 is an attractive therapeutic target for oncological conditions.

P2X7 receptor involved in antitumor activity of atractylenolide I in human cervical cancer cells

Atractylenolide I (Atr-I) was found to sensitize a variety of human cancer cells in previous studies. Purinergic P2X7R plays important role in different cancers. However, whether Atr-I could generate antitumor activity in human cervical cancer cells and P2X7R get involved in this effect remain unclear. In this study, Hela (HPV 18 +) and SiHa (HPV 16 +) cells were treated with different doses of Atr-I. The results indicated that agonist and antagonist of P2X7 receptors, BzATP and JNJ-47965567 (JNJ), could suppress the proliferation of Hela and SiHa cells. Atr-I demonstrated a considerable antitumor effect in both human cervical cancer cells in vitro. Atr-I combined with P2X7R agonist, BzATP, restored Atr-I-induced growth inhibition in Hela cells but not in SiHa cells. However, the combinatorial treatment of P2X7R antagonist JNJ and Atr-I has an additive effect on cell growth inhibition in SiHa cells rather than in Hela cells. It implied that P2X7R would get involved in the anti-human cervical cancer cells effect of Atr-I.

Research Progress in the Relationship Between P2X7R and Cervical Cancer

Cervical cancer is one of the most common and serious tumors in women. Finding new biomarkers and therapeutic targets plays an important role in the diagnosis, prognosis, and treatment of cervical cancer. Purinergic ligand-gated ion channel 7 receptor (P2X7R) is a purine ligand cation channel, activated by adenosine triphosphate (ATP). Studies have shown that P2X7R plays an important role in a variety of diseases and cancers. More and more studies have shown that P2X7R is also closely related to cervical cancer; therefore, the role of P2X7R in the development of cervical cancer deserves further discussion. The expression level of P2X7R in uterine epithelial cancer tissues was lower than that of the corresponding normal tissues. P2X7R plays an important role in the apoptotic process of cervical cancer through various mechanisms of action, and both antagonists and agonists of P2X7R can inhibit the proliferation of cervical cancer cells, while P2X7R is involved in the antitumor effect of Atr-I on cervical cancer cells. This review evaluates the current role of P2X7R in cervical cancer in order to develop more specific therapies for cervical cancer. In conclusion, P2X7R may become a biomarker for cervical cancer screening, and even a new target for clinical treatment of cervical cancer.

P2RX7 promotes osteosarcoma progression and glucose metabolism by enhancing c-Myc stabilization

BACKGROUND

Osteosarcoma is the most common malignant tumor in bone and its prognosis has reached a plateau in the past few decades. Recently, metabolic reprogramming has attracted increasing attention in the field of cancer research. In our previous study, P2RX7 has been identified as an oncogene in osteosarcoma. However, whether and how P2RX7 promotes osteosarcoma growth and metastasis through metabolic reprogramming remains unexplored.

METHODS

We used CRISPR/Cas9 genome editing technology to establish P2RX7 knockout cell lines. Transcriptomics and metabolomics were performed to explore metabolic reprogramming in osteosarcoma. RT-PCR, western blot and immunofluorescence analyses were used to determine gene expression related to glucose metabolism. Cell cycle and apoptosis were examined by flowcytometry. The capacity of glycolysis and oxidative phosphorylation were assessed by seahorse experiments. PET/CT was carried out to assess glucose uptake in vivo.

RESULTS

We demonstrated that P2RX7 significantly promotes glucose metabolism in osteosarcoma via upregulating the expression of genes related to glucose metabolism. Inhibition of glucose metabolism largely abolishes the ability of P2RX7 to promote osteosarcoma progression. Mechanistically, P2RX7 enhances c-Myc stabilization by facilitating nuclear retention and reducing ubiquitination-dependent degradation. Furthermore, P2RX7 promotes osteosarcoma growth and metastasis through metabolic reprogramming in a predominantly c-Myc-dependent manner.

CONCLUSIONS

P2RX7 plays a key role in metabolic reprogramming and osteosarcoma progression via increasing c-Myc stability. These findings provide new evidence that P2RX7 might be a potential diagnostic and/or therapeutic target for osteosarcoma. Novel therapeutic strategies targeting metabolic reprogramming appear to hold promise for a breakthrough in the treatment of osteosarcoma.

Spotlight on P2X7 Receptor PET Imaging: A Bright Target or a Failing Star?

The homotrimeric P2X7 receptor (P2X7R) is expressed by virtually all cells of the innate and adaptive immune system and plays a crucial role in various pathophysiological processes such as autoimmune and neurodegenerative diseases, inflammation, neuropathic pain and cancer. Consequently, the P2X7R is considered a promising target for therapy and diagnosis. As the development of tracers comes hand-in-hand with the development of potent and selective receptor ligands, there is a rising number of PET tracers available in preclinical and clinical studies. This review analyzes the development of P2X7R positron emission tomography (PET) tracers and their potential in various PET imaging applications.

Origin, distribution, and function of three frequent coding polymorphisms in the gene for the human P2X7 ion channel

P2X7, an ion channel gated by extracellular ATP, is widely expressed on the plasma membrane of immune cells and plays important roles in inflammation and apoptosis. Several single nucleotide polymorphisms have been identified in the human P2RX7 gene. In contrast to other members of the P2X family, non-synonymous polymorphisms in P2X7 are common. Three of these occur at overall frequencies of more than 25% and affect residues in the extracellular “head”-domain of P2X7 (155 Y/H), its “lower body” (270 R/H), and its “tail” in the second transmembrane domain (348 T/A). Comparison of the P2X7 orthologues of human and other great apes indicates that the ancestral allele is Y—R—T (at 155–270–348). Interestingly, each single amino acid variant displays lower ATP-sensitivity than the ancestral allele. The originally published reference sequence of human P2X7, often referred to as “wildtype,” differs from the ancestral allele at all three positions, i.e. H—H—A. The 1,000 Genome Project determined the sequences of both alleles of 2,500 human individuals, including roughly 500 persons from each of the five major continental regions. This rich resource shows that the ancestral alleles Y155, R270, and T348 occur in all analyzed human populations, albeit at strikingly different frequencies in various subpopulations (e.g., 25%–59% for Y155, 59%–77% for R270, and 13%–47% for T348). BLAST analyses of ancient human genome sequences uncovered several homozygous carriers of variant P2X7 alleles, possibly reflecting a high degree of inbreeding, e.g., H—R—T for a 50.000 year old Neanderthal, H—R—A for a 24.000 year old Siberian, and Y—R—A for a 7,000 year old mesolithic European. In contrast, most present-day individuals co-express two copies of P2X7 that differ in one or more amino acids at positions 155, 270, and 348. Our results improve the understanding of how P2X7 structure affects its function and suggest the importance of considering P2X7 variants of participants when designing clinical trials targeting P2X7.

P2X7 receptor as the regulator of T-cell function in intestinal barrier disruption

The intestinal mucosa is a highly compartmentalized structure that forms a direct barrier between the host intestine and the environment, and its dysfunction could result in a serious disease. As T cells, which are important components of the mucosal immune system, interact with gut microbiota and maintain intestinal homeostasis, they may be involved in the process of intestinal barrier dysfunction. P2X7 receptor (P2X7R), a member of the P2X receptors family, mediates the effects of extracellular adenosine triphosphate and is expressed by most innate or adaptive immune cells, including T cells. Current evidence has demonstrated that P2X7R is involved in inflammation and mediates the survival and differentiation of T lymphocytes, indicating its potential role in the regulation of T cell function. In this review, we summarize the available research about the regulatory role and mechanism of P2X7R on the intestinal mucosa-derived T cells in the setting of intestinal barrier dysfunction.

Regulating the Expression of HIF-1α or lncRNA: Potential Directions for Cancer Therapy

Previous studies have shown that tumors under a hypoxic environment can induce an important hypoxia-responsive element, hypoxia-induced factor-1α (HIF-1α), which can increase tumor migration, invasion, and metastatic ability by promoting epithelial-to-mesenchymal transition (EMT) in tumor cells. Currently, with the deeper knowledge of long noncoding RNAs (lncRNAs), more and more functions of lncRNAs have been discovered. HIF-1α can regulate hypoxia-responsive lncRNAs under hypoxic conditions, and changes in the expression level of lncRNAs can regulate the production of EMT transcription factors and signaling pathway transduction, thus promoting EMT progress. In conclusion, this review summarizes the regulation of the EMT process by HIF-1α and lncRNAs and discusses their relationship with tumorigenesis. Since HIF-1α plays an important role in tumor progression, we also summarize the current drugs that inhibit tumor progression by modulating HIF-1α.

ATP-gated P2X7 receptor as a potential target for prostate cancer

Prostate cancer is the most common malignancy of the male genitourinary system and is one of the leading causes of male cancer death. The P2X7 receptor is an important member of purine receptor family. It is a gated ion channel with adenosine triphosphate (ATP) as the ligand, which exists in a variety of immune tissues and cells and can be involved in tumorigenesis and tumor progression. Studies have shown that the P2X7 receptor is abnormally expressed in prostate cancer, and is related to the level of prostate-specific antigen, P2X7 receptor may be an early biomarker of prostate cancer. The P2X7 receptor is essential in the occurrence and development of prostate cancer. The P2X7 receptor mainly affects the invasion and metastasis of prostate cancer cells through epithelial mesenchymal transition/invasion-related genes and the PI3K/AKT and ERK1/2 signaling pathways. The P2X7 receptor could be a promising therapeutic target for prostate cancer.

A loss-of-function polymorphism in ATG16L1 compromises therapeutic outcome in head and neck carcinoma patients

The anticancer immune response is shaped by immunogenic cell stress and death pathways. Thus, cancer cells can release danger-associated molecular patterns that act on pattern recognition receptors expressed by dendritic cells and their precursors to elicit an antitumor immune response. Here, we investigated the impact of single nucleotide polymorphisms (SNPs) in genes affecting this cancer-immunity dialogue in the context of head and neck squamous cell carcinoma (HNSCC). We observed that homozygosity for a loss-of-function SNP (rs2241880, leading to the substitution of a threonine residue in position 300 by an alanine) affecting autophagy related 16 like 1 (ATG16L1) is coupled to poor progression-free survival in platinum-treated HNSCC patients. This result was obtained on a cohort of patients enrolled at the Gustave Roussy Cancer Campus and was validated on an independent cohort of The Cancer Genome Atlas (TCGA). Homozygosity in rs2241880 is well known to predispose to Crohn’s disease, and epidemiological associations between Crohn’s disease and HNSCC have been reported at the levels of cancer incidence and prognosis. We speculate that rs2241880 might be partially responsible for this association.

Effect of Regorafenib on P2X7 Receptor Expression and Different Oncogenic Signaling Pathways in a Human Breast Cancer Cell Line: A Potential of New Insight of the Antitumor Effects of Regorafenib

BACKGROUND

Breast cancer is the most common malignancy in women worldwide. P2X7 is a transmembrane receptor expressed in breast cancer and activated by the ATP tumor microenvironment, driving cell proliferation, angiogenesis, and metastasis via different signaling pathways. The role of the P2X7 receptor, hypoxia, and autophagy in regulating tumor progression is controversial. The multikinase inhibitor regorafenib prevents the activation of numerous kinases involved in angiogenesis, proliferation, and metastasis. The present study aimed to evaluate the modulatory effect of regorafenib on the hypoxia/angiogenesis/P2X7R/autophagy axis on the MCF7 breast cancer cell line and its impact on different signaling pathways involved in breast cancer pathogenesis.

METHODS

The levels of VEGF, VEGFR, PI3K, NF-κB, HIF-1α, and LC3-II were analyzed using ELISA, and caspase-3 activity was also assessed colorimetrically. Phosphorylated (p)-p38 MAPK and purinergic ligand-gated ion channel 7 (P2X7) receptor protein expression levels were analyzed via Western blotting. Reverse transcription-quantitative PCR was used to determine the mRNA expression levels of Beclin 1 (BECN1), LC3-II, and sequestosome 1 (p62).

RESULTS

Regorafenib reduced MCF7 cell viability in a dose-dependent manner. Furthermore, regorafenib significantly reduced levels of PI3K, NF-κB, VEGF, VEGFR, P2X7 receptor, and p-p38 MAPK protein expression, and markedly reduced p62 mRNA expression levels. However, regorafenib significantly increased caspase-3 activity, as well as BECN1 and LC3-II mRNA expression levels.

CONCLUSIONS

Regorafenib was demonstrated to possibly exhibit antitumor activity on the breast cancer cell line via modulation of the P2X7/HIF-1α/VEGF, P2X7/P38, P2X7/ERK/NF-κB, and P2X7/beclin 1 pathways.

Current and Future Therapies for Immunogenic Cell Death and Related Molecules to Potentially Cure Primary Breast Cancer

Simple Summary

How a cure for primary breast cancer after (neo)adjuvant therapy can be achieved at the molecular level remains unclear. Immune activation by anticancer drugs may contribute to the eradication of residual tumor cells by postoperative (neo)adjuvant chemotherapy. In addition, chemotherapy-induced immunogenic cell death (ICD) may result in long-term immune activation by memory effector T cells, leading to the curing of primary breast cancer. In this review, we discuss the molecular mechanisms by which anticancer drugs induce ICD and immunogenic modifications for antitumor immunity and targeted therapy against damage-associated molecular patterns. Our aim was to gain a better understanding of how to eradicate residual tumor cells treated with anticancer drugs and cure primary breast cancer by enhancing antitumor immunity with immune checkpoint inhibitors and vaccines.

Abstract

How primary breast cancer can be cured after (neo)adjuvant therapy remains unclear at the molecular level. Immune activation by anticancer agents may contribute to residual tumor cell eradication with postsurgical (neo)adjuvant chemotherapy. Chemotherapy-induced immunogenic cell death (ICD) may result in long-term immune activation with memory effector T cells, leading to a primary breast cancer cure. Anthracycline and taxane treatments cause ICD and immunogenic modulations, resulting in the activation of antitumor immunity through damage-associated molecular patterns (DAMPs), such as adenosine triphosphate, calreticulin, high mobility group box 1, heat shock proteins 70/90, and annexin A1. This response may eradicate residual tumor cells after surgical treatment. Although DAMP release is also implicated in tumor progression, metastasis, and drug resistance, thereby representing a double-edged sword, robust immune activation by anticancer agents and the subsequent acquisition of long-term antitumor immune memory can be essential components of the primary breast cancer cure. This review discusses the molecular mechanisms by which anticancer drugs induce ICD and immunogenic modifications for antitumor immunity and targeted anti-DAMP therapy. Our aim was to improve the understanding of how to eradicate residual tumor cells treated with anticancer drugs and cure primary breast cancer by enhancing antitumor immunity with immune checkpoint inhibitors and vaccines.

Mechanosensitive ion channels in cell migration

Cellular processes are initiated and regulated by different stimuli, including mechanical forces. Cell membrane mechanosensors represent the first step towards the conversion of mechanical stimuli to a biochemical or electrical response. Mechanosensitive (MS) ion channels form a growing family of ion gating channels that respond to direct physical force or plasma membrane deformations. A number of calcium (Ca2+) permeable MS channels are known to regulate the initiation, direction, and persistence of cell migration during development and tumour progression. While the evidence that links individual MS ion channels to cell migration is growing, a unified analysis of the molecular mechanisms regulated downstream of MS ion channel activation is lacking. In this review, we describe the MS ion channel families known to regulate cell migration. We discuss the molecular mechanisms that act downstream of MS ion channels with an emphasis on Ca2+ mediated processes. Finally, we propose the future directions and impact of MS ion channel activity in the field of cell migration.