Tumorigenesis: cell defense against hypoxia?

AhR and HIF-1α Signaling Pathways in Benign Meningioma under Hypoxia

The role of hypoxia in benign meningiomas is less clear than that in the malignant meningiomas. Hypoxia-induced transcription factor 1 subunit alpha (HIF-1α) and its downstream signaling pathways play a central role in the mechanism of hypoxia. HIF-1α forms a complex with the aryl hydrocarbon receptor nuclear translocator (ARNT) protein and can compete for ARNT with aryl hydrocarbon receptor (AhR). In this work, the status of HIF-1α- and AhR-dependent signaling pathways was investigated in World Health Organization (WHO) grade 1 meningioma and patient-derived tumor primary cell culture under hypoxic conditions. mRNA levels of HIF-1α, AhR, and of their target genes as well as of ARNT and nuclear receptor coactivator NCOA2 were determined in tumor tissues from patients in whom the tumor was promptly removed either with or without prior endovascular embolization. Using the patient-derived nonembolized tumor primary cell culture, the effects of a hypoxia mimetic cobalt chloride (CoCl₂) and an activator of the AhR signaling pathway benzo(α)pyrene (B[a]P) on mRNA levels of HIF-1α, AhR, and their target genes were investigated. Our findings show active functioning of AhR signaling in meningioma tissue of patients with tumor embolization and crosstalk between HIF-1α and AhR signaling in meningeal cells under hypoxia.

Promises and Challenges of Predictive Blood Biomarkers for Locally Advanced Rectal Cancer Treated with Neoadjuvant Chemoradiotherapy

The treatment of locally advanced rectal cancer (LARC) requires a multimodal approach combining neoadjuvant radiotherapy or chemoradiotherapy (CRT) and surgery. Predicting tumor response to CRT can guide clinical decision making and improve patient care while avoiding unnecessary toxicity and morbidity. Circulating biomarkers offer both the advantage to be easily accessed and followed over time. In recent years, biomarkers such as proteins, blood cells, or nucleic acids have been investigated for their predictive value in oncology. We conducted a comprehensive literature review with the aim to summarize the status of circulating biomarkers predicting response to CRT in LARC. Forty-nine publications, of which forty-seven full-text articles, one review and one systematic review, were retrieved. These studies evaluated circulating markers (CEA and CA 19-9), inflammatory biomarkers (CRP, albumin, and lymphocytes), hematologic markers (hemoglobin and thrombocytes), lipids and circulating nucleic acids (cell-free DNA [cfDNA], circulating tumor DNA [ctDNA], and microRNA [miRNA]). Post-CRT CEA levels had the most consistent association with tumor response, while cfDNA integrity index, MGMT promoter methylation, ERCC-1, miRNAs, and miRNA-related SNPs were identified as potential predictive markers. Although circulating biomarkers hold great promise, inconsistent results, low statistical power, and low specificity and sensibility prevent them from reliably predicting tumor response following CRT. Validation and standardization of methods and technologies are further required to confirm results.

Exosomes: Small Vesicles with Important Roles in the Development, Metastasis and Treatment of Breast Cancer

Breast cancer (BC) has now overtaken lung cancer as the most common cancer, while no biopredictive marker isolated from biological fluids has yet emerged clinically. After traditional chemotherapy, with the huge side effects brought by drugs, patients also suffer from the double affliction of drugs to the body while fighting cancer, and they often quickly develop drug resistance after the drug, leading to a poor prognosis. And the treatment of some breast cancer subtypes, such as triple negative breast cancer (TNBC), is even more difficult. Exosomes (Exos), which are naturally occurring extracellular vesicles (EVs) with nanoscale acellular structures ranging in diameter from 40 to 160 nm, can be isolated from various biological fluids and have been widely studied because they are derived from the cell membrane, have extremely small diameter, and are widely involved in various biological activities of the body. It can be used directly or modified to make derivatives or to make some analogs for the treatment of breast cancer. This review will focus on the involvement of exosomes in breast cancer initiation, progression, invasion as well as metastasis and the therapeutic role of exosomes in breast cancer.

Immunotherapy Using Oxygenated Water and Tumor-Derived Exosomes Potentiates Antitumor Immune Response and Attenuates Malignancy Tendency in Mice Model of Breast Cancer

Breast cancer is one of the most common type of tumor and the leading cause of death in the world's female population. Various therapeutic approaches have been used to treat tumors but have not led to complete recovery and have even damaged normal cells in the body. Moreover, metastatic tumors such as breast cancer are much more resistant to treatment, and current treatments have not been very successful in treating them and remain a challenge. Therefore, new approaches should be applied to overcome this problem. Given the importance of hypoxia in tumor survival, we aimed to test the antitumor effects of oxygenated water to decrease hypoxia along with tumor-derived exosomes to target tumor. The purpose of administering oxygenated water and tumor exosomes was to reduce hypoxia and establish an effective immune response against tumor antigens, respectively. For this purpose, the breast cancer mice model was induced using the 4T1 cell line in Balb/c mice and treated with oxygenated water via an intratumoral (IT) and/or intraperitoneal (IP) route and/or exosome (TEX). Oxygenation via the IT+IP route was more efficient than oxygenation via the IT or IP route. The efficiency of oxygenation via the two routes along with TEX led to the best therapeutic outcome. Antitumor immune responses directed by TEX became optimized when systemic (IP) and local (IT) oxygenation was applied compared to administration of TEX alone. Results demonstrated a significant reduction in tumor size and the highest levels of IFN-γ and IL-17 and the lowest levels of IL-4 FoxP3, HIF-1α, VEGF, MMP-2, and MMP-9 in the IT+IP+TEX-treated group. Oxygenated water on the one hand could reduce tumor size, hypoxia, angiogenesis, and metastasis in the tumor microenvironment and on the other hand increases the effective immune response against the tumor systemically. This therapeutic approach is proposed as a new strategy for devising vaccines in a personalized approach.

The Effect of Proinflammatory Cytokines on the Proliferation, Migration and Secretory Activity of Mesenchymal Stem/Stromal Cells (WJ-MSCs) under 5% O2 and 21% O2 Culture Conditions

Treatment with Mesenchymal Stem/Stromal Cells (MSCs) in clinical trials is becoming one of the most-popular and fast-developing branches of modern regenerative medicine, as it is still in an experimental phase. The cross-section of diseases to which these cells are applied is very wide, ranging from degenerative diseases, through autoimmune processes and to acute inflammatory diseases, e.g., viral infections. Indeed, now that first clinical trials applying MSCs against COVID-19 have started, important questions concern not only the therapeutic properties of MSCs, but also the changes that might occur in the cell features as a response to the "cytokine storm" present in the acute phase of an infection and capable of posing a risk to a patient. The aim of our study was thus to assess changes potentially occurring in the biology of MSCs in the active inflammatory environment, e.g., in regards to the cell cycle, cell migration and secretory capacity. The study using MSCs derived from Wharton's jelly (WJ-MSCs) was conducted under two aerobic conditions: 21% O2 vs. 5% O2, since oxygen concentration is one of the key factors in inflammation. Under both oxygen conditions cells were exposed to proinflammatory cytokines involved significantly in acute inflammation, i.e., IFNγ, TNFα and IL-1β at different concentrations. Regardless of the aerobic conditions, WJ-MSCs in the inflammatory environment do not lose features typical for mesenchymal cells, and their proliferation dynamic remains unchanged. Sudden fluctuations in proliferation, the early indicator of potential genetic disturbance, were not observed, while the cells' migration activity increased. The presence of pro-inflammatory factors was also found to increase the secretion of such anti-inflammatory cytokines as IL-4 and IL-10. It is concluded that the inflammatory milieu in vitro does not cause phenotype changes or give rise to proliferation disruption of WJ-MSCs, and nor does it inhibit the secretory properties providing for their use against acute inflammation.

High altitude and cancer: An old controversy

Ecological studies have found that individuals that live at high altitude regions and in places where ultraviolet radiation is maximal, have lower rates of different types of cancer. However, there is evidence that in these same regions, genetic mutations that are prooncogenic, develop, as they are needed to increase human adaptability to hypoxic environments. Debate has arisen between researchers who consider high altitude environments as suitable for human longevity because of its protective effects against malignancies, and scientists that have reported an increased incidence of different type of cancers in these same regions. Evidence is presented that altitude is related to the development of genetic alterations in micro RNAs, p53 protein, lymphocyte activity, decrease in Fas Ligand and other proapoptotic molecules, as well as increase in prometastatic VGEF an HIF. Notwithstanding, higher vitamin D and ultraviolet B levels, and a better metabolic profile, taken together with lower pollution levels hves been related to lower incidence and mortality rates from malignancies in a series of epidemiological studies.

Macrophage M1/M2 polarization

Macrophages can be affected by a variety of factors to change their phenotype and thus affect their function. Activated macrophages are usually divided into two categories, M1-like macrophages and M2-like macrophages. Both M1 macrophages and M2 macrophages are closely related to inflammatory responses, among which M1 macrophages are mainly involved in pro-inflammatory responses and M2 macrophages are mainly involved in anti-inflammatory responses. Improving the inflammatory environment by modulating the activation state of macrophages is an effective method for the treatment of diseases. In this review, we analyzed the mechanism of macrophage polarization from the tumor microenvironment, nanocarriers, nuclear receptor PPARγ, phagocytosis, NF-κB signaling pathways, and other pathways.

Expression of MMP-14 and prognosis in digestive system carcinoma: a meta-analysis and databases validation

Background: The Matrix metalloproteinase-14 (MMP-14) expression has been shown to be overexpressed in different cancers. However, there is no comprehensive quantitative evaluation of the MMP-14 prognostic value in digestive system carcinoma (DSC). The aim of this study is to explore the correlation between the MMP-14 expression and DSC prognosis.

Methods: We conducted a meta-analysis to estimate the association strength between MMP-14 expression and prognosis. GEPIA and Kaplan Meier plotters were used to assess overall survival (OS), disease-free survival (DFS)/progression-free survival (PFS) in DSC patients and the differential expression of MMP-14 in DSC tissues and adjacent tissues.

Results: A total of 20 studies including 2,519 patients with OS and 438 patients with DFS/PFS data were analyzed in evidence synthesis. Overall, the combined hazard ratio (HR) with 95% confidence interval (95% CI) was 1.98 (95%Cl: 1.77-2.22, P<0.001) for OS and 3.61 (95%Cl: 2.39-5.43, P<0.001) for DFS/PFS. For subgroup analyses, significant correlations were revealed between increased MMP-14 expression and poor OS in patients with gastric cancer (HR=2.21, 95%CI: 1.76-2.77, P<0.001), esophageal carcinoma (HR=2.01, 95%CI: 1.58-2.57, P<0.001), oral cancer (HR = 1.69, 95% CI: 1.30-2.20, P < 0.001) (HR=2.14, 95%CI 1.35-2.19, P<0.001) and hepatocarcinoma. In database verification analyses, the MMP-14 expression levels in normal tissues were significantly higher than that in DSC tissues, and significant associations were observed between high MMP-14 expression levels and poor prognosis.

Conclusions: The high expression levels of MMP-14 might predict poor prognosis in DSC. Larger prospective clinical cohort studies are required to validate the prognostic role.

A review on the role of M2 macrophages in bladder cancer; pathophysiology and targeting

Tumor-associated macrophages (TAMs) which are often referred to as immunosuppressive cells (M2 macrophage), constitute a subset of tumor microenvironment cells and affect tumor progression in solid tumors. Recently, these cells have gained remarkable importance as therapeutic candidates for solid tumors. In bladder cancer, major studies have focused on evaluating TAMs in response to Bacillus Calmette-Guerin (BCG) therapy. M2 macrophages may directly impact the BCG-induced immune responses against tumor in bladder cancer. They are the main inhibitors of the tumor microenvironment that promotes growth and metastasis of the tumor. However, the clinical significance of M2 macrophages in bladder cancer is controversial. In this review, we will discuss the clinical significance of M2 macrophages in prognosis of bladder cancer as well as worth of their potential targeting in bladder cancer treatment. In the following, we will introduce important factors resulting in M2 macrophage promotion and also experimental therapeutic agents that may cause the inhibition of bladder cancer tumor growth.

The role of the hypoxia-Nrp-1 axis in the activation of M2-like tumor-associated macrophages in the tumor microenvironment of cervical cancer

To explore the mechanisms through which hypoxic tumor microenvironment (TME) modulates the transition of tumor-associated macrophages (TAMs). The migration ability of RAW264.7 macrophages was determined by transwell assay. Flow cytometric, western blot and immunofluorescence analyses of CD206 further validated the M2 polarization of macrophages. Immunofluorescence, western blot and qRT-PCR were performed to detect the expression of neuropilin-1 (Nrp-1) and carbonic anhydrase IX (CAIX). An intermittent hypobaric hypoxia (IH) animal model was established to evaluate the role of hypoxia in activating M2-like TAMs in vivo. We also used immunohistochemistry to analyze the association between CAIX, CD163+ macrophages and Nrp-1 in a series of 72 human cervical cancer specimens. We found that the hypoxic cervical TME educated the recruited macrophages to transform into the M2 phenotype. Nrp-1 expression was significantly increased in hypoxia-primed cervical cancer cells. Blocking Nrp-1 expression prevented hypoxic cells from recruiting and polarizing macrophages towards the M2 phenotype. Hypoxia exposure significantly increased the expression of Nrp-1 as well as the infiltration of macrophages in vivo. Consistently, immunochemical staining in serial tissue sections of cervical cancer revealed upregulated levels of Nrp-1 in CAIX-positive hypoxic regions along with a concurrent significant elevation of M2 macrophages. Nrp-1 and M2-like TAMs were related to the malignant properties of cervical cancer, such as the FIGO stage and lymph node metastasis. Nrp-1 plays critical roles in hypoxic TME-induced activation and pro-tumoral effects of TAMs in cervical cancer. Interfering with Nrp-1 may be a potential therapeutic strategy in treating cervical cancer.

Macrophages are recruited to hypoxic tumor areas and acquire a pro-angiogenic M2-polarized phenotype via hypoxic cancer cell derived cytokines Oncostatin M and Eotaxin

TAMs, a unique and distinct M2-skewed myeloid population of tumor stroma, exhibiting pro-tumor functions is fast emerging as a potential target for anti-cancer immunotherapy. Macrophage-recruitment and M2-polarization represent key TAMs-related phenomenon that are amenable to therapeutic intervention. However successful translation of these approaches into effective therapeutic regimen requires better characterization of tumor-microenvironment derived signals that regulate macrophage recruitment and their polarization. Owing to hypoxic milieu being a persistent feature of tumor-microenvironment and a major contributor to malignancy and treatment resistance, the current study was planned with an aim to decipher tumor cell responses to hypoxia vis-a-vis macrophage homing and phenotype switching. Here, we show that hypoxia-primed cancer cells chemoattract and polarize macrophages to pro-angiogenic M2-polarized subtype via Eotaxin and Oncostatin M. Concordantly, hypoxic regions of human breast-cancer specimen exhibited elevated Eotaxin and Oncostatin M levels with concurrently elevated M2-macrophage content. Blockade of Eotaxin/Oncostatin M not only prevented hypoxic breast-cancer cells from recruiting and polarizing macrophages towards an M2-polarized phenotype and retarded tumor progression in 4T1/BALB/c-syngenic-mice-model of breast-cancer but also enhanced the efficacy of anti-angiogenic Bevacizumab. The findings established these two cytokines as novel targets for devising effective anticancer therapy particularly for tumors that are refractory or develop resistance to anti-angiogenic therapeutics.