15-Deoxy-Δ12,14-prostaglandin J2 Upregulates VEGF Expression via NRF2 and Heme Oxygenase-1 in Human Breast Cancer Cells

Prostaglandin 15d-PGJ2 inhibits proliferation of lung adenocarcinoma cells by inducing ROS production and activation of apoptosis via sirtuin-1

Lung adenocarcinoma (LUADC) belongs to the most prevalent and lethal cancer types. As 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) displays anti-oxidative, -inflammatory, and -cancer properties, we investigated whether this cyclopentenone PG, a stable degradation end-product of cyclooxygenase-generated PGD2, exerts beneficial effects in three LUADC cell lines (A549, H1299, H23). We here report that 15d-PGJ2 had substantial cytotoxic effects in all three LUADC cell lines by promoting early apoptosis and inhibiting the cell cycle, proliferation, and migration. As indicators of cell malignancy, scratch closure and colony formation were significantly inhibited by 15d-PGJ2. 15d-PGJ2 induced generation of ROS and subsequent activation of MAPKs. Expression of Nrf-2, a well-known tumor driver, was markedly diminished by 15d-PGJ2 treatment. Although PPARγ, DP1, and DP2 are expressed in LUADC cells, blocking these receptors with specific inhibitors (SR16832 and BW245C) did not reverse 15d-PGJ2-mediated cytotoxicity, suggesting receptor-independent effects. 15d-PGJ2 decreased SIRT1 expression in LUADC cells and the knockdown of SIRT1 diminished the cytotoxic effects of 15d-PGJ2. Importantly, 15d-PGJ2 significantly reduced tumor growth using the chorioallantoic membrane (CAM) assay. The structural analog of 15d- PGJ2, 9,10-dihydro-15d-PGJ2 (lacking the α,β-unsaturated ketone structural element), did not show any toxic effects in LUADC cells. Altogether, our findings suggest that 15d-PGJ2 led to significantly reduced tumor growth and cell proliferation in three LUADC cell lines. The CAM assay results suggest that 15d-PGJ2 is a suitable endogenous compound to interfere with LUADC tumor progression. We show that SIRT1 modulates the effects of 15d-PGJ2 and may be used as a therapeutic target for LUADC.

Preliminary Comparison of Molecular Antioxidant and Inflammatory Mechanisms Determined in the Peripheral Blood Granulocytes of COVID-19 Patients

The aim of this study was to evaluate selected parameters of redox signaling and inflammation in the granulocytes of COVID-19 patients who recovered and those who died. Upon admission, the patients did not differ in terms of any relevant clinical parameter apart from the percentage of granulocytes, which was 6% higher on average in those patients who died. Granulocytes were isolated from the blood of 15 healthy people and survivors and 15 patients who died within a week, and who were selected post hoc for analysis according to their matching gender and age. They differed only in the lethal outcome, which could not be predicted upon arrival at the hospital. The proteins level (respective ELISA), antioxidant activity (spectrophotometry), and lipid mediators (UPUPLC-MS) were measured in the peripheral blood granulocytes obtained via gradient centrifugation. The levels of Nrf2, HO-1, NFκB, and IL-6 were higher in the granulocytes of COVID-19 patients who died within a week, while the activity of cytoplasmic Cu,Zn-SOD and mitochondrial Mn-SOD and IL-2/IL-10 were lower in comparison to the levels observed in survivors. Furthermore, in the granulocytes of those patients who died, an increase in pro-inflammatory eicosanoids (PGE2 and TXB2), together with elevated cannabinoid receptors 1 and 2 (associated with a decrease in the anti-inflammatory 15d-PGJ2), were found. Hence, this study suggests that by triggering transcription factors, granulocytes activate inflammatory and redox signaling, leading to the production of pro-inflammatory eicosanoids while reducing cellular antioxidant capacity through SOD, thus expressing an altered response to COVID-19, which may result in the onset of systemic oxidative stress, ARDS, and the death of the patient.

Docosahexaenoic Acid as Master Regulator of Cellular Antioxidant Defenses: A Systematic Review

Docosahexaenoic acid (DHA) is a polyunsaturated fatty acid that benefits the prevention of chronic diseases. Due to its high unsaturation, DHA is vulnerable to free radical oxidation, resulting in several unfavorable effects, including producing hazardous metabolites. However, in vitro and in vivo investigations suggest that the relationship between the chemical structure of DHA and its susceptibility to oxidation may not be as clear-cut as previously thought. Organisms have developed a balanced system of antioxidants to counteract the overproduction of oxidants, and the nuclear factor erythroid 2-related factor 2 (Nrf2) is the key transcription factor identified for transmitting the inducer signal to the antioxidant response element. Thus, DHA might preserve the cellular redox status promoting the transcriptional regulation of cellular antioxidants through Nrf2 activation. Here, we systematically summarize the research on the possible role of DHA in controlling cellular antioxidant enzymes. After the screening process, 43 records were selected and included in this review. Specifically, 29 studies related to the effects of DHA in cell cultures and 15 studies concerned the effects of consumption or treatment with DHA in animal. Despite DHA's promising and encouraging effects at modulating the cellular antioxidant response in vitro/in vivo, some differences observed among the reviewed studies may be accounted for by the different experimental conditions adopted, including the time of supplementation/treatment, DHA concentration, and cell culture/tissue model. Moreover, this review offers potential molecular explanations for how DHA controls cellular antioxidant defenses, including involvement of transcription factors and the redox signaling pathway.

Commelina benghalensis (Wandering Jew) Linn exhibits abortifacient potentials and hepatotoxicity in pregnant Wistar rats via elevating indicators of oxidative stress and activating proinflammatory cytokines

ETHNOPHARMACOLOGICAL RELEVANCE

Commelina benghalensis Linn is a perennial plant with upright stems reaching a height of 1 m. Its stem is commonly used to induce abortion in traditional medicine. However, there are insignificant scientific data to evaluate such a claim.

AIM OF THE STUDY

The study was conducted to determine the abortifacient and toxicological potential of ethanol extract of Commelina benghalensis Linn stem (EECBS) via selected proinflammatory and oxidative stress biomarkers in pregnant Wistar rats.

MATERIALS AND METHODS

To determine the phytochemicals responsible for EECBS's toxicity and abortifacient effects, high-performance liquid chromatography-photodiode array detection (HPLC-PDA) and gas chromatography-mass spectrometry (GC-MS) was used. The abortion rate was determined by monitoring the markers of reproductive system failure in the experimental model. To assess rat hepatotoxicity, biochemical markers and immunohistopathological parameters were used.

RESULTS

Results demonstrated the presence of isomeric benzene-mesitylene compounds in EECBS. Also, EECBS significantly altered the markers of liver function and oxidative damage while eliciting a significantly reduced (P < 0.05) number of live fetuses, number of corpora lutea, progesterone, estradiol, and luteinizing hormone, whereas the number of dead fetuses percentage vaginal opening, and post-implantation loss increased significantly (P < 0.05). Estrogenicity studies indicated a significant (P < 0.05) increase in uterine weight, uterine glucose, and ALP dose-dependently. Moreover, EECBS also caused a vaginal hemorrhage preceding the parturition. Also, EECBS treatment significantly increased levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and significantly elevated the expression of COX-2 protein in the liver.

CONCLUSION

The current investigation established Commelina benghalensis Linn stem's abortifacient activity. Continuous use, on the other hand, may cause liver damage in pregnant rats by disrupting antioxidant defense mechanisms, promoting the production of pro-inflammatory cytokines, and increasing COX-2 expression. Hence, caution should be excised while consuming this plant's stem for medication purposes, especially during the gestational period.

Gasotransmitter-Induced Therapeutic Angiogenesis: A Biomaterial Prospective

Gasotransmitters such as NO, H₂S, and CO have emerged as key players in the regulation of various pathophysiological functions, prompting the development of gas therapy for various pathogeneses. Deficient production of gasotransmitters has been linked to various diseases such as hypertension, endothelial dysfunction, myocardial infarction, ischemia, and impaired wound healing, as they are involved in the regulatory action of angiogenesis. A better understanding of the regulatory mechanisms has given new hope to address the vascular impairment caused by the breakthroughs in gasotransmitters as therapeutics. However, the unstable nature and poor target specificity of gas donors limit the full efficacy of drugs. In this regard, biomaterials that possess excellent biocompatibility and porosity are ideal drug carriers to deliver the gas transmitters in a tunable manner for therapeutic angiogenesis. This review article provides a comprehensive discussion of biomaterial-based gasotransmitter delivery approaches for therapeutic angiogenesis. The critical role of gasotransmitters in modulating angiogenesis during tissue repair as well as their challenges and future directions are demonstrated.

Mechanisms underlying Nrf2 nuclear translocation by non-lethal levels of hydrogen peroxide: p38 MAPK-dependent neutral sphingomyelinase2 membrane trafficking and ceramide/PKCζ/CK2 signaling

Hydrogen peroxide is an aerobic metabolite playing a central role in redox signaling and oxidative stress. H₂O₂ could activate redox sensitive transcription factors, such as Nrf2, AP-1 and NF-κB by different manners. In some cells, treatment with non-lethal levels of H₂O₂ induces rapid activation of Nrf2, which upregulates expression of a set of genes involved in glutathione (GSH) synthesis and defenses against oxidative damage. It depends on two steps, the rapid translational activation of Nrf2 and facilitation of Nrf2 nuclear translocation. We review the molecular mechanisms by which H₂O₂ induces nuclear translocation of Nrf2 in cultured cells by highlighting the role of neutral sphingomyelinase 2 (nSMase2), a GSH sensor. H₂O₂ enters cells through aquaporin channels in the plasma membrane and is rapidly reduced to H₂O by GSH peroxidases to consume cellular GSH, resulting in nSMase2 activation to generate ceramide. H₂O₂ also activates p38 MAP kinase, which enhances transfer of nSMase2 from perinuclear regions to plasma membrane lipid rafts to accelerate ceramide generation. Low levels of ceramide activate PKCζ, which then activates casein kinase 2 (CK2). These protein kinases are able to phosphorylate Nrf2 to stabilize and activate it. Notably, Nrf2 also binds to caveolin-1 (Cav1), which protects Nrf2 from Keap1-mediated degradation and limits Nrf2 nuclear translocation. We propose that Cav1serves as a signaling hub for the control of H₂O₂-mediated phosphorylation of Nrf2 by kinases, which results in release of Nrf2 from Cav1 to facilitate nuclear translocation. In summary, H₂O₂ induces GSH depletion which is recovered by Nrf2 activation dependent on p38/nSMase2/ceramide signaling.

Puzzling Out Iron Complications in Cancer Drug Resistance

Iron metabolism are frequently disrupted in cancer. Patients with cancer are prone to anemia and receive transfusions frequently; the condition which results in iron overload, contributing to serious therapeutic complications. Iron is introduced as a carcinogen that may increase tumor growth. However, investigations regarding its impact on response to chemotherapy, particularly the induction of drug resistance are still limited. Here, iron contribution to cell signaling and various molecular mechanisms underlying iron-mediated drug resistance are described. A dual role of this vital element in cancer treatment is also addressed. On one hand, the need to administer iron chelators to surmount iron overload and improve the sensitivity of tumor cells to chemotherapy is discussed. On the other hand, the necessary application of iron as a therapeutic option by iron-oxide nanoparticles or ferroptosis inducers is explained. Authors hope that this paper can help unravel the clinical complications related to iron in cancer therapy.

miR-140-5p Attenuates Hypoxia-Induced Breast Cancer Progression by Targeting Nrf2/HO-1 Axis in a Keap1-Independent Mechanism

Hypoxia and oxidative stress significantly contribute to breast cancer (BC) progression. Although hypoxia-inducible factor 1α (Hif-1α) is considered a key effector of the cellular response to hypoxia, nuclear factor erythroid 2-related factor 2 (Nrf2), a master antioxidant transcription factor, is a crucial factor essential for Hif-1α-mediated hypoxic responses. Hence, targeting Nrf2 could provide new treatment strategies for cancer therapy. miRNAs are potential regulators of hypoxia-responsive genes. In a quest to identify novel hypoxia-regulated miRNAs involved in the regulation of Nrf2, we found that miR-140-5p significantly affects the expression of Nrf2 under hypoxia. In our study, miR-140-5p expression is downregulated in BC cells under hypoxic conditions. We have identified Nrf2 as a direct target of miR-140-5p, as confirmed by the luciferase assay. Knockdown of miR-140-5p under normoxic conditions significantly enhanced Nrf2/HO-1 signaling and tumor growth, angiogenesis, migration, and invasion in BC. In contrast, overexpression of miR-140-5p under hypoxic conditions revealed opposite results. Further silencing Nrf2 expression mimicked the miR-140-5p-induced anti-tumor effects. Consistent with the knockdown of miR-140-5p in vitro, mice injected with miR-140-5p-KD cells exhibited dramatically reduced miR-140-5p levels, increased Nrf2 levels, and increased tumor growth. In contrast, tumor growth is potently suppressed in mice injected with miR-140-5p-OE cells. Collectively, the above results demonstrate the importance of the Nrf2/HO-1 axis in cancer progression and, thus, targeting Nrf2 by miR-140-5p could be a better strategy for the treatment of Nrf2-driven breast cancer progression.

15d-PGJ2 Promotes ROS-Dependent Activation of MAPK-Induced Early Apoptosis in Osteosarcoma Cell In Vitro and in an Ex Ovo CAM Assay

Osteosarcoma (OS) is the most common type of bone tumor, and has limited therapy options. 15-Deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂) has striking anti-tumor effects in various tumors. Here, we investigated molecular mechanisms that mediate anti-tumor effects of 15d-PGJ₂ in different OS cell lines. Human U2-OS and Saos-2 cells were treated with 15d-PGJ₂ and cell survival was measured by MTT assay. Cell proliferation and motility were investigated by scratch assay, the tumorigenic capacity by colony forming assay. Intracellular ROS was estimated by H₂DCFDA. Activation of MAPKs and cytoprotective proteins was detected by immunoblotting. Apoptosis was detected by immunoblotting and Annexin V/PI staining. The ex ovo CAM model was used to study growth capability of grafted 15d-PGJ₂-treated OS cells, followed by immunohistochemistry with hematoxylin/eosin and Ki-67. 15d-PGJ₂ substantially decreased cell viability, colony formation and wound closure capability of OS cells. Non-malignant human osteoblast was less affected by 15d-PGJ₂. 15d-PGJ₂ induced rapid intracellular ROS production and time-dependent activation of MAPKs (pERK1/2, pJNK and pp38). Tempol efficiently inhibited 15d-PGJ₂-induced ERK1/2 activation, while N-acetylcystein and pyrrolidine dithiocarbamate were less effective. Early but weak activation of cytoprotective proteins was overrun by induction of apoptosis. A structural analogue, 9,10-dihydro-15d-PGJ₂, did not show toxic effects in OS cells. In the CAM model, we grafted OS tumors with U2-OS, Saos-2 and MG-63 cells. 15d-PGJ₂ treatment resulted in significant growth inhibition, diminished tumor tissue density, and reduced tumor cell proliferation for all cell lines. Our in vitro and CAM data suggest 15d-PGJ₂ as a promising natural compound to interfere with OS tumor growth.

STAT3 as a Potential Target for Tumor Suppressive Effects of 15-Deoxy-Δ12,14-prostaglandin J2 in Triple Negative Breast Cancer

STAT3 plays a prominent role in proliferation and survival of tumor cells. Thus, STAT3 has been considered to be a prime target for development of anti-cancer therapeutics. The electrophilic cyclopentenone prostaglandin,15-deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂) has been well recognized for its capability to modulate intracellular signaling pathways involved in cancer cell growth and progression. We previously reported that 15d-PGJ₂ had potent cytotoxicity against harvey-ras transformed human mammary epithelial cells through direct interaction with STAT3. In this study, we have attempted to verify the inhibitory effects of 15d-PGJ₂ on STAT3 signaling in human breast tumor cells. The triple negative breast cancer cell lines, MDA-MB-231 and MDA-MB-468 displaying constitutive phosphorylation of STAT3 on the tyrosine 705 (Tyr705) residue, underwent apoptosis upon inhibition of STAT3 by 15d-PGJ₂. In contrast, estrogen receptor positive MCF-7 breast cancer cells that do not exhibit elevated STAT3 phosphorylation were much less susceptible to 15d-PGJ₂-induced apoptosis as assessed by PARP cleavage. Furthermore, 15d-PGJ₂ inhibited interleukin-6-induced tyrosine phosphorylation of STAT3 in LNCaP cells. According to molecular docking studies, 15d-PGJ₂ may preferentially bind to the cysteine 259 residue (Cys259) present in the coiled-coil domain of STAT3. Site-directed mutagenesis of STAT3 identified Cys259 to be the critical amino acid for the 15d-PGJ₂-induced apoptosis as well as epithelial-to-mesenchymal transition. Taken together, these findings suggest STAT3 inactivation through direct chemical modification of its Cys259 as a potential therapeutic approach for treatment of triple negative breast cancer treatment.

Role of Oxidative Stress and Nrf2/KEAP1 Signaling in Colorectal Cancer: Mechanisms and Therapeutic Perspectives with Phytochemicals

Colorectal cancer still has a high incidence and mortality rate, according to a report from the American Cancer Society. Colorectal cancer has a high prevalence in patients with inflammatory bowel disease. Oxidative stress, including reactive oxygen species (ROS) and lipid peroxidation, has been known to cause inflammatory diseases and malignant disorders. In particular, the nuclear factor erythroid 2-related factor 2 (Nrf2)/Kelch-like ECH-related protein 1 (KEAP1) pathway is well known to protect cells from oxidative stress and inflammation. Nrf2 was first found in the homolog of the hematopoietic transcription factor p45 NF-E2, and the transcription factor Nrf2 is a member of the Cap 'N' Collar family. KEAP1 is well known as a negative regulator that rapidly degrades Nrf2 through the proteasome system. A range of evidence has shown that consumption of phytochemicals has a preventive or inhibitory effect on cancer progression or proliferation, depending on the stage of colorectal cancer. Therefore, the discovery of phytochemicals regulating the Nrf2/KEAP1 axis and verification of their efficacy have attracted scientific attention. In this review, we summarize the role of oxidative stress and the Nrf2/KEAP1 signaling pathway in colorectal cancer, and the possible utility of phytochemicals with respect to the regulation of the Nrf2/KEAP1 axis in colorectal cancer.