Mutant TP53 modulates metastasis of triple negative breast cancer through adenosine A2b receptor signaling

Adenosine receptors in breast cancer

Adenosine receptors are important in the normal physiological function of cells and the pathogenesis of various cancer cells, including breast cancer cells. The activity of adenosine receptors in cancer cells is related to cell proliferation, angiogenesis, metastasis, immune system evasion, and interference with apoptosis. Considering the different roles of adenosine receptors in cancer cells, we intend to investigate the function of adenosine receptors and their biological pathways in breast cancer to improve understanding of therapeutically relevant signaling pathways.

Facts and prospects of peptide in targeted therapy and immune regulation against triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer. Due to the lack of specific therapeutic targets, treatment options are limited, and the recurrence and metastasis rate is high, the overall survival of patients is poor. However, with the discovery of some new targets and the corresponding immune regulation after targeting these targets, TNBC has a new hope in treatment. The peptide has a simple structure, strong binding affinity, and high stability, and has great potential in targeted therapy and immune regulation against TNBC. This review will discuss how single peptides and peptide combinations target triple-negative breast cancer to exert immunomodulatory effects. Among them, single peptides target specific receptors on TNBC cells, act as decoys to target key ligands in the regulatory pathway, and target TME-related cells. The combinations of peptides work in the form of cancer vaccines, engineered exosomes, microRNAs and other immune-related molecular pathways, immune checkpoint inhibitors, chimeric antigen receptor T cells, and drug-peptide conjugates. This article is mainly dedicated to exploring new treatment methods for TNBC to improve the curative effect and prolong the survival time of patients.

Adenosine Receptor A2B Antagonist Inhibits the Metastasis of Gastric Cancer Cells and Enhances the Efficacy of Cisplatin

Adenosine receptors play a key role in cancer progression. This study investigated the effect of the adenosine A2B receptor (ADORA2B) on epithelial-mesenchymal transition (EMT) markers and cell metastasis of gastric cancer (GC) cells. Public databases were used to investigate the specificity of ADORA2B expression in GC tissue. We used immunohistochemistry and immunofluorescence to detect ADORA2B expression in GC tissue, paracancerous tissue, and metastatic greater omental tissue. AGS and HGC-27 GC cells were selected. The effect of ADORA2B on the invasion and migration of GC cells was examined using cell scratch and transwell assays. The effect of ADORA2B on the expression of EMT marker proteins (β-catenin, N-cadherin, and vimentin) in GC cells was measured by cellular immunohistochemistry, immunofluorescence, and Western blot. The effects of an ADORA2B inhibitor combined with cisplatin on EMT markers in GC cells were further explored. The expression levels of ADORA2B in GC tissue, metastatic greater omental tissue, and lymphatic metastasis tissue were significantly higher than those in paracancerous tissue, and ADORA2B was associated with lymph node metastasis and invasion. ADORA2B significantly regulated the invasion and migration ability of GC cells and the expression levels of EMT marker proteins. The combination of an ADORA2B antagonist (PSB-603) and cisplatin had a more significant effect on reversing the expression of EMT marker proteins. ADORA2B was overexpressed in GC tissue, metastatic greater omental tissue, and metastatic lymph node tissue. ADORA2B regulated the expression of EMT marker proteins in GC cells and affected GC cell metastasis. Antagonizing ADORA2B expression increased the efficacy of cisplatin treatment.

Role of p53 in breast cancer progression: An insight into p53 targeted therapy

The transcription factor p53 is an important regulator of a multitude of cellular processes. In the presence of genotoxic stress, p53 is activated to facilitate DNA repair, cell cycle arrest, and apoptosis. In breast cancer, the tumor suppressive activities of p53 are frequently inactivated by either the overexpression of its negative regulator MDM2, or mutation which is present in 30-35% of all breast cancer cases. Notably, the frequency of p53 mutation is highly subtype dependent in breast cancers, with majority of hormone receptor-positive or luminal subtypes retaining the wild-type p53 status while hormone receptor-negative patients predominantly carry p53 mutations with gain-of-function oncogenic activities that contribute to poorer prognosis. Thus, a two-pronged strategy of targeting wild-type and mutant p53 in different subtypes of breast cancer can have clinical relevance. The development of p53-based therapies has rapidly progressed in recent years, and include unique small molecule chemical inhibitors, stapled peptides, PROTACs, as well as several genetic-based approaches using vectors and engineered antibodies. In this review, we highlight the therapeutic strategies that are in pre-clinical and clinical development to overcome p53 inactivation in both wild-type and mutant p53-bearing breast tumors, and discuss their efficacies and limitations in pre-clinical and clinical settings.

MALAT-1/p53/miR-155/miR-146a ceRNA circuit tuned by methoxylated quercitin glycoside alters immunogenic and oncogenic profiles of breast cancer

Triple-Negative Breast Cancer (TNBC) is one of the most aggressive and hot BC subtypes. Our research group has recently shed the light on the utility of natural compounds as effective immunotherapeutic agents. The aim of this study is to investigate the role of a methoxylated quercetin glycoside (MQG) isolated from Cleome droserifolia in harnessing TNBC progression and tuning the tumor microenvironment and natural killer cells cytotoxicity. Results showed that MQG showed the highest potency (IC₅₀ = 12 µM) in repressing cellular proliferation, colony-forming ability, migration, and invasion capacities. Mechanistically, MQG was found to modulate a circuit of competing endogenous RNAs where it was found to reduce the oncogenic MALAT-1 lncRNA and induce TP53 and its downstream miRNAs; miR-155 and miR-146a. Accordingly, this leads to alteration in several downstream signaling pathways such as nitric oxide synthesizing machinery, natural killer cells' cytotoxicity through inducing the expression of its activating ligands such as MICA/B, ULBP2, CD155, and ICAM-1 and trimming of the immune-suppressive cytokines such as TNF-α and IL-10. In conclusion, this study shows that MQG act as a compelling anti-cancer agent repressing TNBC hallmarks, activating immune cell recognition, and alleviating the immune-suppressive tumor microenvironment experienced by TNBC patients.

Cancer driver gene and non-coding RNA alterations as biomarkers of brain metastasis in lung cancer: A review of the literature

Brain metastasis (BM) is the most common event in patients with lung cancer. Despite multimodal treatments and advances in systemic therapies, development of BM remains one of the main factors associated with poor prognosis and mortality in patients with lung cancer. Therefore, better understanding of mechanisms involved in lung cancer brain metastasis (LCBM) is of great importance to suppress cancer cells and to improve the overall survival of patients. Several cancer-related genes such as EGFR and KRAS have been proposed as potential predictors of LCBM. In addition, there is ample evidence supporting crucial roles of non-coding RNAs (ncRNAs) in mediating LCBM. In this review, we provide comprehensive information on risk assessment, predictive, and prognostic panels for early detection of BM in patients with lung cancer. Moreover, we present an overview of LCBM molecular mechanisms, cancer driver genes, and ncRNAs which may predict the risk of BM in lung cancer patients. Recent clinical studies have focused on determining mechanisms involved in LCBM and their association with diagnosis, prognosis, and treatment outcomes. These studies have shown that alterations in EGFR, KRAS, BRAF, and ALK, as the most frequent coding gene alterations, and dysregulation of ncRNAs such as miR-423, miR-330-3p, miR-145, piR-651, and MALAT1 can be considered as potential biomarkers of LCBM.

Molecular Targeting of RRM2, NF-κB, and Mutant TP53 for the Treatment of Triple-Negative Breast Cancer

Doxorubicin and other anthracycline derivatives are frequently used as part of the adjuvant chemotherapy regimen for triple-negative breast cancer (TNBC). Although effective, doxorubicin is known for its off-target and toxic side effect profile, particularly with respect to the myocardium, often resulting in left ventricular (LV) dysfunction and congestive heart failure when used at cumulative doses exceeding 400 mg/m² Previously, we have observed that the ribonucleotide reductase subunit M2 (RRM2) is significantly overexpressed in estrogen receptor (ER)-negative cells as compared with ER-positive breast cancer cells. Here, we inhibited RRM2 in ER-negative breast cancer cells as a target for therapy in this difficult-to-treat population. We observed that through the use of didox, a ribonucleotide reductase inhibitor, the reduction in RRM2 was accompanied by reduced NF-κB activity in vitro When didox was used in combination with doxorubicin, we observed significant downregulation of NF-κB proteins accompanied by reduced TNBC cell proliferation. As well, we observed that protein levels of mutant p53 were significantly reduced by didox or combination therapy in vitro Xenograft studies showed that combination therapy was found to be synergistic in vivo, resulting in a significantly reduced tumor volume as compared with doxorubicin monotherapy. In addition, the use of didox was also found to ameliorate the toxic myocardial effects of doxorubicin in vivo as measured by heart mass, LV diameter, and serum troponin T levels. The data present a novel and promising approach for the treatment of TNBC that merits further clinical evaluation in humans.

The PI3K/mTOR dual inhibitor NVP-BEZ235 stimulates mutant p53 degradation to exert anti-tumor effects on triple-negative breast cancer cells

Nearly half of human cancers harbor p53 mutations, and mutant p53 (mutp53) promotes carcinogenesis, metastasis, tumor recurrence and chemoresistance. mutp53 is observed in 30% of breast carcinomas, including triple-negative breast cancer (TNBC), and thus mutp53 is a promising target for treatment of TNBC. In this study, we investigated the effect of a phosphatidylinositide 3 kinase/mammalian target of rapamycin dual inhibitor, NVP-BEZ235 (BEZ235), on two TNBC cell lines with mutp53: MDA-MB-231 and MDA-MB-468. Cell growth, migration and colony-formation abilities were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide, scratch assay, transwell and soft agar assay, revealing that BEZ235 can inhibit the growth, migration and colony-formation abilities of TNBC cells. In addition, BEZ235 caused degradation of mutp53 in these cells. We investigated the underlying mechanism by inhibiting proteasome function using MG132 and inhibiting autophagy using 3-methyladenine and shRNAs. We observed that BEZ235 may induce autophagy through repression of the Akt/mammalian target of rapamycin signaling pathway. The observed interplay between mutp53 and autophagy in TNBC cells was examined further by knockdown of ATG5 and ATG7, revealing that degradation of mutp53 induced by BEZ235 may be independent of the ubiquitin-proteasome pathway and autophagy mediated by ATG5 and ATG7. Moreover, we found evidence of positive feedback between mutp53 and autophagy in TNBC cells. In conclusion, BEZ235 may exert antitumor effects against TNBC cells by targeting mutp53, and this may have implications for the development of future therapies.

High-Throughput RNA Interference Screen Targeting Synthetic-Lethal Gain-of-Function of Oncogenic Mutant TP53 in Triple-Negative Breast Cancer

TNBC is an aggressive and metastatic subtype of breast cancer in which TP53 mutation occurs frequently and is associated with particularly poor outcome. Mutations in TP53 can disrupt the intrinsic function of the tumor suppressor as well as acquire oncogenic gain-of-function (GOF) activities. However, little is known about its oncogenic GOF mediators and functions. Targeted therapy for TNBC patients is thus one of the most urgent needs in breast cancer therapeutics, and identifying genes that have synthetic lethal interactions with mutant TP53 may be a promising approach. In this chapter, we present procedures on sequential analysis of RNA-seq followed by high-throughput RNA interference screening (HTS-RNAi screening). This approach has been utilized to identify genes with synthetic lethality of mutant TP53, providing a promising strategy for the treatment of mutant TP53 in TNBC and determining its impact on tumorigenesis.

Expression of Adenosine Receptors in Rodent Pancreas

Adenosine regulates exocrine and endocrine secretions in the pancreas. Adenosine is considered to play a role in acini-to-duct signaling in the exocrine pancreas. To identify the molecular basis of functional adenosine receptors in the exocrine pancreas, immunohistochemical analysis was performed in the rat, mouse, and guinea pig pancreas, and the secretory rate and concentration of HCO₃⁻ in pancreatic juice from the rat pancreas were measured. The A_2A adenosine receptor colocalized with ezrin, an A-kinase anchoring protein, in the luminal membrane of duct cells in the mouse and guinea pig pancreas. However, a strong signal ascribed to A_2B adenosine receptors was detected in insulin-positive β cells in islets of Langerhans. The A_2A adenosine receptor agonist 4-[2-[[6-Amino-9-(N-ethyl-β-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzenepropanoic acid (CGS 21680) stimulated HCO₃⁻-rich fluid secretion from the rat pancreas. These results indicate that A_2A adenosine receptors may be, at least in part, involved in the exocrine secretion of pancreatic duct cells via acini-to-duct signaling. The adenosine receptors may be a potential therapeutic target for cancer as well as exocrine dysfunctions of the pancreas.

A2B Adenosine Receptor and Cancer

There are four subtypes of adenosine receptors (ARs), named A₁, A_2A, A_2B and A₃, all of which are G protein-coupled receptors (GPCRs). Locally produced adenosine is a suppressant in anti-tumor immune surveillance. The A_2BAR, coupled to both Gαs and Gαi G proteins, is one of the several GPCRs that are expressed in a significantly higher level in certain cancer tissues, in comparison to adjacent normal tissues. There is growing evidence that the A_2BAR plays an important role in tumor cell proliferation, angiogenesis, metastasis, and immune suppression. Thus, A_2BAR antagonists are novel, potentially attractive anticancer agents. Several antagonists targeting A_2BAR are currently in clinical trials for various types of cancers. In this review, we first describe the signaling, agonists, and antagonists of the A_2BAR. We further discuss the role of the A_2BAR in the progression of various cancers, and the rationale of using A_2BAR antagonists in cancer therapy.