p53 is an important regulator of CCL2 gene expression

AT2R Activation Improves Wound Healing in a Preclinical Mouse Model

Abnormal skin healing resulting in chronic wounds or hypertrophic scarring remains a major healthcare burden. Here, the antifibrotic angiotensin II type 2 receptor (AT2R) signaling pathway was modulated to determine its impact on cutaneous wound healing. Balb/c mice received two splinted full-thickness wounds. Topical treatments with the selective AT2R agonist compound 21 (C21) and/or selective antagonist PD123319 or saline vehicle were administered until sacrifice on post-wounding days 7 or 10. The rate of wound re-epithelialization was accelerated by PD123319 and combination treatments. In vitro, C21 significantly reduced human fibroblast migration. C21 increased both collagen and vascular densities at days 7 and 10 post-wounding and collagen I:III ratio at day 10, while PD123319 and combination treatments decreased them. Genes associated with regeneration and repair were upregulated by C21, while PD123319 treatment increased the expression of genes associated with inflammation and immune cell chemotaxis. C21 treatment reduced wound total leukocyte and neutrophil staining densities, while PD123319 increased these and macrophage densities. Overall, AT2R activation with C21 yields wounds that mature more quickly with structural, cellular, and gene expression profiles more closely approximating unwounded skin. These findings support AT2R signal modulation as a potential therapeutic target to improve skin quality during wound healing.

The role of p53 in anti-tumor immunity and response to immunotherapy

p53 is a transcription factor that regulates the expression of genes involved in tumor suppression. p53 mutations mediate tumorigenesis and occur in approximately 50% of human cancers. p53 regulates hundreds of target genes that induce various cell fates including apoptosis, cell cycle arrest, and DNA damage repair. p53 also plays an important role in anti-tumor immunity by regulating TRAIL, DR5, TLRs, Fas, PKR, ULBP1/2, and CCL2; T-cell inhibitory ligand PD-L1; pro-inflammatory cytokines; immune cell activation state; and antigen presentation. Genetic alteration of p53 can contribute to immune evasion by influencing immune cell recruitment to the tumor, cytokine secretion in the TME, and inflammatory signaling pathways. In some contexts, p53 mutations increase neoantigen load which improves response to immune checkpoint inhibition. Therapeutic restoration of mutated p53 can restore anti-cancer immune cell infiltration and ameliorate pro-tumor signaling to induce tumor regression. Indeed, there is clinical evidence to suggest that restoring p53 can induce an anti-cancer immune response in immunologically cold tumors. Clinical trials investigating the combination of p53-restoring compounds or p53-based vaccines with immunotherapy have demonstrated anti-tumor immune activation and tumor regression with heterogeneity across cancer type. In this Review, we discuss the impact of wild-type and mutant p53 on the anti-tumor immune response, outline clinical progress as far as activating p53 to induce an immune response across a variety of cancer types, and highlight open questions limiting effective clinical translation.

Understanding the characteristics of the host genome and microbiome interaction in oral squamous cell carcinoma: a narrative review

Background

Oral health status is directly associated with microbes present within it. The abundance of microbes at the OSCC site is more than at its control site, representing its possible role in the progression of OSCC development. Dysbiosis of oral microbiota could be a crucial etiological risk factor in the elevation of OSCC. This study aimed to analyze and assess: a) positive regulator microbes of oral cancer and their abundance at the cancer site, b) pathways involved in positive regulator microbes, and c) identification of the most virulent oral oncogenic microbe.

Main body

It is obtained from several studies that microbes belonging to Prevotella, Fusobacterium, Alloprevotella, Capnocytophaga, Porphyromonas, Campylobacter, and Aggregatibacter are detected to be more in number contrast to healthy sites. Fusobacterium nucleatum, Porphyromonas gingivalis, and Candida albicans show molecular pathways linked with OSCC development. Genes encoding for virulent factors like FimA, Gingipains, lipopolysaccharide (P. gingivalis), FadA, Fap2 (F. nucleatum), and zymosan (C. Albicans) are directly involved in elevating oral cancer.

Conclusion

Mostly, the genes that are involved in promoting oral cancer are the genes that generally encode cell wall proteins. The cell wall proteins that is FadA, Fap, and FimA interact with the host's cell and hamper the normal regulation pathway, which leads to activation of cell proliferating pathways, down-regulates apoptotic pathways, cytoskeleton rearrangement, and upregulates the cell cycle checkpoint regulators; as a result, progression of oral cancer occurs.

The Key Network of mRNAs and miRNAs Regulated by HIF1A in Hypoxic Hepatocellular Carcinoma Cells

Purpose: Hypoxia plays an essential role in the progression of hepatocellular carcinoma (HCC), whereas hypoxia inducible factor-1 (HIF-1) is the key transcription factor allowing HCC to survive hypoxia. The aim of this study was to define the essential mRNAs and miRNAs regulated by HIF1A and dissect their functions, interactions, and tumor-infiltrating immune cells in HCC. Methods: A human HCC cell line HepG2 was used as a cell model of HCC. The CRISPR/Cas9 system was used to knock out HIF1A in HepG2 cells, and RNA sequencing was utilized to characterize differentially expressed mRNAs and miRNAs in the HIF1A-knockout HepG2 cells; the identified candidates were then analyzed by GO annotation and KEGG pathway enrichment to study their function and establish a PPI network. Quantitative (q) PCR was used to verify if there were significant differences in the expression of mRNAs, and the association of the selected mRNAs expression with immune cell infiltration levels was further analyzed using The Cancer Genome Atlas (TCGA) pan-cancer data. Results: Using RNA-sequencing, we discovered that there were 1535 mRNAs differentially expressed (adjusted p < 0.05, |fold change|>1.5) in the HIF1A-knockout HepG2 cells, among which there were 644 mRNAs upregulated and 891 mRNAs downregulated. GO annotation and KEGG pathway enrichment showed that these mRNAs were involved in glycolysis/gluconeogenesis, PI3K-Akt signaling pathways, and HIF-1 signaling pathways. In addition, we found that there were 309 miRNAs differentially expressed (adjusted p < 0.05, |fold change|>1.5) in the HIF1A-knockout HepG2 cells, of which there were 213 miRNAs upregulated and 96 miRNAs downregulated. Our further analyses uncovered that these miRNA putative targets were involved in the hippo signaling pathway, axon guidance, and tight junction. Moreover, the construction and analysis of the PPI network showed that OASL, IL6, and TAF1 were recognized as hub genes with the highest connectivity degrees. Importantly, in the HIF1A-knockout HepG2 cells, our qRT-PCR data confirmed the selected mRNA changes revealed by RNA-sequencing, and with TCGA pan-cancer data, we revealed that the expressional levels of these three genes, LUM, SCOC, and CCL2, were associated with immune cell infiltration levels. Conclusion: The identified potential key network of mRNAs and miRNAs regulated by HIF1A in the HCC cells suggests a key role of HIF1A in the tumorigenesis of HCC.

Porphyromonas gingivalis upregulates calbindin 1 and thus promotes the proliferation of gingival epithelial cells

OBJECTIVES

This study aims to investigate the effect of calbindin 1 on the proliferation and apoptosis of gingival epithelial cells affected by Porphyromonas gingivalis (P. gingivalis)invitro.

METHODS

A model of P. gingivalis infecting CA9-22 was established in vitro. At 24 h after infection, the expression of calbindin 1 (CALB1) was detected by real-time fluorescent quantitative polymerase chain reaction, Western blot, and immunofluorescence analyses. The expression of CALB1 was further inhibited by RNA interference. Cell proliferation was detected by BrdU analysis, and cell apoptosis was detected by caspase 3 activity. The expression of MDM2 and p53 was detected by Western blot analysis.

RESULTS

P. gingivalis infection upregulated the expression of CALB1 in CA9-22 cells with multiplicity-dependent manner. CALB1 promoted the proliferation of CA9-22 cells, increased the expression of MDM2, and inhibited the expression of p53. Inhibiting CALB1 expression did not affect the inhibitory effect of P. gingivalis infection on CA9-22 apoptosis.

CONCLUSIONS

P. gingivalis infection can promote the proliferation of CA9-22 cells by increasing CALB1 expression. The related mechanism may be associated with MDM2-p53.

P53 in the impaired lungs

Our laboratory is focused on investigating the supportive role of P53 towards the maintenance of lung homeostasis. Acute lung injury, acute respiratory distress syndrome, chronic obstructive pulmonary disease, pulmonary fibrosis, bronchial asthma, pulmonary arterial hypertension, pneumonia and tuberculosis are respiratory pathologies, associated with dysfunctions of this endothelium defender (P53). Herein we review the evolving role of P53 towards the aforementioned inflammatory disorders, to potentially reveal new therapeutic possibilities in pulmonary disease.

Deficiency of miR-208a Exacerbates CCl4-Induced Acute Liver Injury in Mice by Activating Cell Death Pathways

Acute liver injury (ALI) is associated with multiple cellular events such as necrosis, apoptosis, oxidative stress and inflammation, which can lead to liver failure. In this study, we demonstrate a new role of microRNA (miR)‐208a in ALI. ALI was induced in wild‐type (WT) and miR‐208a knockout (KO) mice by CCl₄ administration. Increased alanine aminotransferase and decreased hepatic miR‐208a levels were found in WT mice after acute CCl₄ treatment. Histopathological evaluations revealed increased necrosis and decreased inflammation in miR‐208a KO compared with WT mice after CCl₄ treatment. CCl₄ treatment induced a higher alanine aminotransferase elevation and increased numbers of circulating extracellular vesicles (exosomes and microvesicles) in miR‐208a KO compared with WT mice. We found increased CCl₄‐induced nuclear factor kappa B activation and tumor necrosis factor‐α induction and decreased monocyte chemoattractant protein 1 levels in miR‐208a KO compared with WT mice. Terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick‐end labeling assay indicated aggravated hepatic apoptosis and necrosis in CCl₄‐treated miR‐208a KO compared with WT mice. CCl₄ treatment induced a greater increase in cleaved caspase‐8, p18, and caspase‐3 in miR‐208a KO compared with WT mice. p53 is involved in various cell death pathways, including necrosis and apoptosis. Our in silico analysis revealed p53 as a predicted miR‐208a target, and we found enhanced p53 and cyclophilin D protein expressions in miR‐208a KO mice after CCl₄ treatment. Increased liver injury in miR‐208a KO mice was further associated with increased Bax (B cell lymphoma 2–associated X protein) and p21 expression. Our in vitro results indicated a role of miR‐208a in cell death. We found that CCl₄‐induced cytotoxicity was partially rescued by miR‐208a overexpression in RAW macrophages. Altogether, our results revealed a role of miR‐208a in ALI in mice and suggest a role for miR‐208a in regulating cell death.

RETRACTED: Endogenous production of C-C motif chemokine ligand 2 by nasopharyngeal carcinoma cells drives radioresistance-associated metastasis

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Following the publication of the above article, the Editor was notified by a concerned reader that the authors supplied duplicated images. Specifically, overlap in Figures 1C, 4A, 4B, 4D, and 5C. These concerns were also reported at PubPeer https://pubpeer.com/publications/CAC11E726E1C3E261A1F8BB90FF173. After review, the Editor found that duplication did occur and therefore the decision was made to retract the article. After re-examination of the entire paper, raw data and lab records, the authors have found that “pictures between different experiments were carelessly mixed. We want to apologize for all the inconvenience it caused to the editorial board, and to all our peers and to all the readers of our paper.”

The Link between Regional Tidal Stretch and Lung Injury during Mechanical Ventilation

The aim of this study was to assess the association between regional tidal volume (Vt), regional functional residual capacity (FRC), and the expression of genes linked with ventilator-induced lung injury. Two groups of BALB/c mice (n = 8 per group) were ventilated for 2 hours using a protective or injurious ventilation strategy, with free-breathing mice used as control animals. Regional Vt and FRC of the ventilated mice was determined by analysis of high-resolution four-dimensional computed tomographic images taken at baseline and after 2 hours of ventilation and corrected for the volume of the region (i.e., specific [s]Vt and specific [s]FRC). RNA concentrations of 21 genes in 10 different lung regions were quantified using a quantitative PCR array. sFRC at baseline varied regionally, independent of ventilation strategy, whereas sVt varied regionally depending on ventilation strategy. The expression of IL-6 (P = 0.04), Ccl2 (P < 0.01), and Ang-2 (P < 0.05) was associated with sVt but not sFRC. The expression of seven other genes varied regionally (IL-1β and RAGE [receptor for advanced glycation end products]) or depended on ventilation strategy (Nfe2l2 [nuclear factor erythroid-derived 2 factor 2], c-fos, and Wnt1) or both (TNF-α and Cxcl2), but it was not associated with regional sFRC or sVt. These observations suggest that regional inflammatory responses to mechanical ventilation are driven primarily by tidal stretch.

The Photomodulation Activity of Metformin Against Oral Microbiome

Periodontitis is one of the most common inflammatory diseases of the periodontium, which results in the inflammatory destruction of supporting structures around teeth and is closely associated with the development of systemic disease. Due to a wide variety of antibiotic resistance periodontopathic bacteria, photodynamic therapy (PDT) is a non-invasive adjunctive therapeutic modality that is capable of destroying the whole range of microbes. Metformin (Metf) is an antidiabetic drug, and recent studies suggest that cancer patients who receive Metf and are exposed to radiotherapy and chemotherapy show better outcomes. Our surveys in this review introduce Metf as a potent stimulus in increasing the efficacy of PDT in the induction of destruction in microbial cells.

Serological Markers Associated With Response to Immune Checkpoint Blockade in Metastatic Gastrointestinal Tract Cancer

IMPORTANCE

There are a limited number of predictive biomarkers for hyperprogressive disease (HPD), which is induced by immune checkpoint blockade (ICB) therapy.

OBJECTIVE

To evaluate the association of biomarkers in serum with the response to ICB therapy in patients with metastatic gastrointestinal tract cancer.

DESIGN, SETTING, AND PARTICIPANTS

Cohort study in which patients with metastatic gastrointestinal tract cancer treated with ICB were enrolled at the Department of Gastrointestinal Oncology, Peking University Cancer Hospital and Institute, Beijing, China, from August 1, 2015, to July 31, 2017, with the last follow-up date on January 1, 2018. Serum samples were collected at baseline and during the first visit to the clinic after starting treatment. Data analysis was conducted from January 16, 2018, to September 1, 2018.

EXPOSURES

A total of 59 factors, including cytokines/chemokines, growth factors, and soluble checkpoint-related proteins in serum, were examined by multiplexed bead immunoassays.

MAIN OUTCOMES AND MEASURES

Tree-based estimators were used to evaluate the importance of serum protein levels to ICB treatment response. Progression-free survival and overall survival analyses were conducted with the Kaplan-Meier method and log-rank test.

RESULTS

In total, 56 patients were examined. All patients with HPD (5 [8.9%]) had significantly lower mean (SD) levels of serum monocyte chemoattractant protein 1 than patients without HPD at baseline (53.4 [17.3] pg/mL vs 106.4 [48.4] pg/mL; P = .02). All patients with HPD were also identified by lower leukemia inhibitory factor levels (<13.28 pg/mL) and higher cluster of differentiation 152 levels (≥31.81 pg/mL). Among the remaining 51 patients, responders with esophageal squamous cell carcinoma (ESCC) or colorectal cancer (CRC) showed larger decreases in interleukin 1 receptor antagonist levels than nonresponders (ESCC: -55.02% [95% CI, -86.52% to -23.51%] vs 43.44% [95% CI, 11.93% to 74.96%]; P < .001; CRC: -35.82% [95% CI, -67.38% to -4.26%] vs 59.14% [95% CI, -72.34% to 190.6%]; P = .04). Responders with gastric cancer (GC) had larger increases in brain-derived neurotrophic factor levels than nonresponders (44.77% [95% CI, 10.76% to 78.79%] vs -26.2% [95% CI, -58.53% to 6.12%]; P = .003). Furthermore, early decreases in serum interleukin 1 receptor antagonist in patients with metastatic ESCC and CRC were associated with longer progression-free survival (ESCC: not reached vs 2.1 months; hazard ratio, 0.19; 95% CI, 0.04 to 0.95; P = .04; CRC: not reached vs 2.1 months; hazard ratio, 0.06; 95% CI, 0.01 to 0.38; P < .001). Early increases in brain-derived neurotrophic factor levels in patients with metastatic GC were associated with longer progression-free survival (not reached vs 4.2 months; hazard ratio, 0.15; 95% CI, 0.03 to 0.84; P = .03).

CONCLUSIONS AND RELEVANCE

In this study, baseline serum levels of monocyte chemoattractant protein 1, leukemia inhibitory factor, and cluster of differentiation 152 were associated with hyperprogressive metastatic gastrointestinal cancer among patients receiving ICB. An early decrease in serum interleukin 1 receptor antagonist levels in patients with metastatic ESCC or CRC and an early increase in serum brain-derived neurotrophic factor levels in patients with metastatic GC were better able to identify who would respond to ICB compared with microsatellite stability status or programmed cell death ligand 1 expression.

TP53 gain-of-function mutation promotes inflammation in glioblastoma

Glioblastoma (GBM), the most severe and common brain tumor in adults, is characterized by multiple somatic mutations and aberrant activation of inflammatory responses. Immune cell infiltration and subsequent inflammation cause tumor growth and resistance to therapy. Somatic loss-of-function mutations in the gene encoding tumor suppressor protein p53 (TP53) are frequently observed in various cancers. However, numerous studies suggest that TP53 regulates malignant phenotypes by gain-of-function (GOF) mutations. Here we demonstrate that a TP53 GOF mutation promotes inflammation in GBM. Ectopic expression of a TP53 GOF mutant induced transcriptomic changes, which resulted in enrichment of gene signatures related to inflammation and chemotaxis. Bioinformatics analyses revealed that a gene signature, upregulated by the TP53 GOF mutation, is associated with progression and shorter overall survival in GBM. We also observed significant correlations between the TP53 GOF mutation signature and inflammation in the clinical database of GBM and other cancers. The TP53 GOF mutant showed upregulated C-C motif chemokine ligand 2 (CCL2) and tumor necrosis factor alpha (TNFA) expression via nuclear factor kappa B (NFκB) signaling, consequently increasing microglia and monocyte-derived immune cell infiltration. Additionally, TP53 GOF mutation and CCL2 and TNFA expression correlated positively with tumor-associated immunity in patients with GBM. Taken together, our findings suggest that the TP53 GOF mutation plays a crucial role in inflammatory responses, thereby deteriorating prognostic outcomes in patients with GBM.

CRISPR/Cas9-Mediated Trp53 and Brca2 Knockout to Generate Improved Murine Models of Ovarian High-Grade Serous Carcinoma

There is a need for transplantable murine models of ovarian high-grade serous carcinoma (HGSC) with regard to mutations in the human disease to assist investigations of the relationships between tumor genotype, chemotherapy response, and immune microenvironment. In addressing this need, we performed whole-exome sequencing of ID8, the most widely used transplantable model of ovarian cancer, covering 194,000 exomes at a mean depth of 400× with 90% exons sequenced >50×. We found no functional mutations in genes characteristic of HGSC (Trp53, Brca1, Brca2, Nf1, and Rb1), and p53 remained transcriptionally active. Homologous recombination in ID8 remained intact in functional assays. Further, we found no mutations typical of clear cell carcinoma (Arid1a, Pik3ca), low-grade serous carcinoma (Braf), endometrioid (Ctnnb1), or mucinous (Kras) carcinomas. Using CRISPR/Cas9 gene editing, we modeled HGSC by generating novel ID8 derivatives that harbored single (Trp53-/-) or double (Trp53-/-;Brca2-/-) suppressor gene deletions. In these mutants, loss of p53 alone was sufficient to increase the growth rate of orthotopic tumors with significant effects observed on the immune microenvironment. Specifically, p53 loss increased expression of the myeloid attractant CCL2 and promoted the infiltration of immunosuppressive myeloid cell populations into primary tumors and their ascites. In Trp53-/-;Brca2-/- mutant cells, we documented a relative increase in sensitivity to the PARP inhibitor rucaparib and slower orthotopic tumor growth compared with Trp53-/- cells, with an appearance of intratumoral tertiary lymphoid structures rich in CD3+ T cells. This work validates new CRISPR-generated models of HGSC to investigate its biology and promote mechanism-based therapeutics discovery. Cancer Res; 76(20); 6118-29. ©2016 AACR.

Agmatine Ameliorates High Glucose-Induced Neuronal Cell Senescence by Regulating the p21 and p53 Signaling

Neuronal senescence caused by diabetic neuropathy is considered a common complication of diabetes mellitus. Neuronal senescence leads to the secretion of pro-inflammatory cytokines, the production of reactive oxygen species, and the alteration of cellular homeostasis. Agmatine, which is biosynthesized by arginine decarboxylation, has been reported in previous in vitro to exert a protective effect against various stresses. In present study, agmatine attenuated the cell death and the expression of pro-inflammatory cytokines such as IL-6, TNF-alpha and CCL2 in high glucose in vitro conditions. Moreover, the senescence associated-β-galatosidase's activity in high glucose exposed neuronal cells was reduced by agmatine. Increased p21 and reduced p53 in high glucose conditioned cells were changed by agmatine. Ultimately, agmatine inhibits the neuronal cell senescence through the activation of p53 and the inhibition of p21. Here, we propose that agmatine may ameliorate neuronal cell senescence in hyperglycemia.

p53/PUMA expression in human pulmonary fibroblasts mediates cell activation and migration in silicosis

Phagocytosis of SiO₂ into the lung causes an inflammatory cascade that results in fibroblast proliferation and migration, followed by fibrosis. Clinical evidence has indicated that the activation of alveolar macrophages by SiO₂ produces rapid and sustained inflammation characterized by the generation of monocyte chemotactic protein 1, which, in turn, induces fibrosis. However, the details of events downstream of monocyte chemotactic protein 1 activity in pulmonary fibroblasts remain unclear. Here, to elucidate the role of p53 in fibrosis induced by silica, both the upstream molecular mechanisms and the functional effects on cell proliferation and migration were investigated. Experiments using primary cultured adult human pulmonary fibroblasts led to the following results: 1) SiO₂ treatment resulted in a rapid and sustained increase in p53 and PUMA protein levels; 2) the MAPK and PI3K pathways were involved in the SiO₂-induced alteration of p53 and PUMA expression; and 3) RNA interference targeting p53 and PUMA prevented the SiO₂-induced increases in fibroblast activation and migration. Our study elucidated a link between SiO₂-induced p53/PUMA expression in fibroblasts and cell migration, thereby providing novel insight into the potential use of p53/PUMA in the development of novel therapeutic strategies for silicosis treatment.

Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: focus on the cancer hallmark of tumor angiogenesis

One of the important 'hallmarks' of cancer is angiogenesis, which is the process of formation of new blood vessels that are necessary for tumor expansion, invasion and metastasis. Under normal physiological conditions, angiogenesis is well balanced and controlled by endogenous proangiogenic factors and antiangiogenic factors. However, factors produced by cancer cells, cancer stem cells and other cell types in the tumor stroma can disrupt the balance so that the tumor microenvironment favors tumor angiogenesis. These factors include vascular endothelial growth factor, endothelial tissue factor and other membrane bound receptors that mediate multiple intracellular signaling pathways that contribute to tumor angiogenesis. Though environmental exposures to certain chemicals have been found to initiate and promote tumor development, the role of these exposures (particularly to low doses of multiple substances), is largely unknown in relation to tumor angiogenesis. This review summarizes the evidence of the role of environmental chemical bioactivity and exposure in tumor angiogenesis and carcinogenesis. We identify a number of ubiquitous (prototypical) chemicals with disruptive potential that may warrant further investigation given their selectivity for high-throughput screening assay targets associated with proangiogenic pathways. We also consider the cross-hallmark relationships of a number of important angiogenic pathway targets with other cancer hallmarks and we make recommendations for future research. Understanding of the role of low-dose exposure of chemicals with disruptive potential could help us refine our approach to cancer risk assessment, and may ultimately aid in preventing cancer by reducing or eliminating exposures to synergistic mixtures of chemicals with carcinogenic potential.

Brown D, Calaf GM, Castellino RC, Cohen-Solal KA, Colacci A, Cruickshanks N, Dent P, Di Fiore R, Forte S, Goldberg GS, Hamid RA, Krishnan H, Laird DW, Lasfar A, Marignani PA, Memeo L, Mondello C, Naus CC, Ponce-Cusi R, Raju J, Roy D, Roy R, P. Ryan E, Salem HK, Scovassi AI, Singh N, Vaccari M, Vento R, Vondráček J, Wade M, Woodrick J, Bisson WH. Mechanisms of environmental chemicals that enable the cancer hallmark of evasion of growth suppression

As part of the Halifax Project, this review brings attention to the potential effects of environmental chemicals on important molecular and cellular regulators of the cancer hallmark of evading growth suppression. Specifically, we review the mechanisms by which cancer cells escape the growth-inhibitory signals of p53, retinoblastoma protein, transforming growth factor-beta, gap junctions and contact inhibition. We discuss the effects of selected environmental chemicals on these mechanisms of growth inhibition and cross-reference the effects of these chemicals in other classical cancer hallmarks.

p53 suppresses CCL2-induced subcutaneous tumor xenograft

Chemokine (C-C motif) ligand 2 (CCL2) has recently been found to be a key player in the pathology of many human glomerular and tubulointerstitial diseases. CCL2 has also been found to be expressed in various cancers, including human hepatoma cells, human cancer progression, and human multiple myeloma cells. Thus, the inhibition of elevated CCL2 production may provide a new avenue for therapeutic intervention in CCL2-mediated cancer diseases. A previous study has indicated that knockdown of human p53 has a strong negative impact on CCL2 induction. We therefore are interested in how p53 regulates CCL2 gene expression. In the following study, our findings indicate that p53 binds to CCL2, consequently significantly downregulating CCL2 promoter activity. Furthermore, injection of CCL2-promoting cancer cells (CCL2/A549) in p53-deficient mice for 3 weeks strongly induced subcutaneous xenograft tumor growth compared with the control. Overall, the research results support the novel role of p53 in suppression of chemokine (such as CCL2)-mediated cancer diseases.

Total adiponectin, but not inflammatory markers C-reactive protein, tumor necrosis factor-α, interluekin-6 and monocyte chemoattractant protein-1, correlates with increasing glucose intolerance in pregnant Chinese-Americans

BACKGROUND

Elevated insulin, C-reactive protein (CRP), tumor necrosis factor (TNF)-α, interleukin (IL)-6, and monocyte chemoattractant protein (MCP)-1 levels and decreased high molecular weight adiponectin (HMW-APN) levels have been reported in Caucasians with gestational diabetes mellitus (GDM). No similar studies have been performed in Chinese women.

METHODS

Serum samples were obtained 1 h after a 50-g glucose challenge test (1HGCT) from Chinese-American women at 24-28 gestational weeks and total adiponectin (T-APN), HMW-APN, CRP, TNF-α, IL-6, and MCP-1 concentrations were measured. Correlation coefficients for glucose (1HGCT), HbA1c, insulin, and body mass index (BMI) were calculated against T-APN, HMW-APN, CRP, TNF-α, IL-6, and MCP-1. Significant P-values were determined using Bonferroni adjustments.

RESULTS

Women with GDM had higher insulin and 1HGCT and lower T-APN. In addition, T-APN was lower in non-GDM subjects who had 1HGCT ≥135 mg/dL with no abnormal or one abnormal glucose value on the 3-h oral glucose tolerance test. There were no significant differences in HMW-APN and inflammatory marker levels between non-GDM and GDM groups. There were negative correlations between T-APN and 1HGCT, insulin, BMI, and HbA1c, as well as between HMW-APN and 1HGCT, insulin, and BMI. No significant correlations were observed between 1HGCT, HbA1c, insulin, or BMI and CRP, TNF-α, IL-6, or MCP-1.

CONCLUSIONS

T-APN is reduced in Chinese women with GDM and those without GDM but with evidence of glucose intolerance. Unlike results reported for Caucasians, Chinese-American women with GDM do not exhibit elevated levels of CRP, TNF-α, IL-6, or MCP-1, possibly because Chinese women are relatively leaner compared with Caucasians.

The inflammatory cytokine TNFα cooperates with Ras in elevating metastasis and turns WT-Ras to a tumor-promoting entity in MCF-7 cells

Background

In the present study we determined the relative contribution of two processes to breast cancer progression: (1) Intrinsic events, such as activation of the Ras pathway and down-regulation of p53; (2) The inflammatory cytokines TNFα and IL-1β, shown in our published studies to be highly expressed in tumors of >80% of breast cancer patients with recurrent disease.

Methods

Using MCF-7 human breast tumor cells originally expressing WT-Ras and WT-p53, we determined the impact of the above-mentioned elements and cooperativity between them on the expression of CXCL8 (ELISA, qRT-PCR), a member of a “cancer-related chemokine cluster” that we have previously identified. Then, we determined the mechanisms involved (Ras-binding-domain assays, Western blot, luciferase), and tested the impact of Ras + TNFα on angiogenicity (chorioallantoic membrane assays) and on tumor growth at the mammary fat pad of mice and on metastasis, in vivo.

Results

Using Ras^G12V that recapitulates multiple stimulations induced by receptor tyrosine kinases, we found that Ras^G12V alone induced CXCL8 expression at the mRNA and protein levels, whereas down-regulation of p53 did not. TNFα and IL-1β potently induced CXCL8 expression and synergized with Ras^G12V, together leading to amplified CXCL8 expression. Testing the impact of WT-Ras, which is the common form in breast cancer patients, we found that WT-Ras was not active in promoting CXCL8; however, TNFα has induced the activation of WT-Ras: joining these two elements has led to cooperative induction of CXCL8 expression, via the activation of MEK, NF-κB and AP-1. Importantly, TNFα has led to increased expression of WT-Ras in an active GTP-bound form, with properties similar to those of Ras^G12V. Jointly, TNFα + Ras activities have given rise to increased angiogenesis and to elevated tumor cell dissemination to lymph nodes.

Conclusions

TNFα cooperates with Ras in promoting the metastatic phenotype of MCF-7 breast tumor cells, and turns WT-Ras into a tumor-supporting entity. Thus, in breast cancer patients the cytokine may rescue the pro-cancerous potential of WT-Ras, and together these two elements may lead to a more aggressive disease. These findings have clinical relevance, suggesting that we need to consider new therapeutic regimens that inhibit Ras and TNFα, in breast cancer patients.

Immune surveillance of unhealthy cells by natural killer cells

Pathogenic and oncogenic insults result in the induction of intrinsic defense mechanisms such as cell-death pathways and senescence, and extrinsic pathways that mobilize immune responses to destroy unhealthy cells. Both protective mechanisms presumably evolved to limit the damage these insults could inflict on the host. After viral infection or malignant transformation, unhealthy cells can be directly sensed by natural killer (NK) and some T cells via the activating receptor NKG2D. All NK cells and subsets of T cells express NKG2D. The NKG2D/ligand system represents a major recognition mechanism for detection and elimination of unhealthy cells. Here we discuss different pathways, including stress pathways, that are responsible for cell-surface display of ligands for NKG2D, which are self-proteins that are minimally expressed by normal cells. We also discuss new results indicating that efficient elimination of tumor cells that display NKG2D ligands depends on the recruitment of NK cells and other immune cells to the tumor, which can be regulated by distinct mechanisms, including the p53-dependent production of chemokines by senescent tumors. The cooperative effect of pathways that induce the display of NKG2D ligands and distinct pathways that mobilize immune cells provides a higher degree of specificity to the NK cell response.

p53-dependent chemokine production by senescent tumor cells supports NKG2D-dependent tumor elimination by natural killer cells

p53 induction regulates NK cell recruitment via CCL2, leading to NKG2D-dependent elimination of senescent tumors.

The induction of cellular senescence is an important mechanism by which p53 suppresses tumorigenesis. Using a mouse model of liver carcinoma, where cellular senescence is triggered in vivo by inducible p53 expression, we demonstrated that NK cells participate in the elimination of senescent tumors. The elimination of senescent tumor cells is dependent on NKG2D. Interestingly, p53 restoration neither increases ligand expression nor increases the sensitivity to lysis by NK cells. Instead, p53 restoration caused tumor cells to secrete various chemokines with the potential to recruit NK cells. Antibody-mediated neutralization of CCL2, but not CCL3, CCL4 or CCL5, prevented NK cell recruitment to the senescent tumors and reduced their elimination. Our findings suggest that elimination of senescent tumors by NK cells occurs as a result of the cooperation of signals associated with p53 expression or senescence, which regulate NK cell recruitment, and other signals that induce NKG2D ligand expression on tumor cells.