Disruption of NF-κB signaling by fluoxetine attenuates MGMT expression in glioma cells

Fluoxetine as a Potential Therapeutic Agent for Inhibiting Melanoma Brain and Lung Metastasis: Induction of Apoptosis, G0/G1 Cell Cycle Arrest, and Disruption of Autophagy Flux

Brain metastases and lung metastases are major causes of treatment failure and related mortality in melanoma. Fluoxetine hydrochloride (FXT), a widely-used antidepressant, has emerged as a potential anticancer agent in preclinical studies. Previous research has shown its potential to inhibit melanoma. However, its efficacy and the underlying mechanisms in melanoma metastasis, especially concerning brain metastases and lung metastases, remain underexplored. This study investigates FXT's inhibitory effects on melanoma growth and metastasis to the lung and brain. Employing a combination of in vitro assays, we demonstrate FXT's potent suppression of melanoma growth through induction of intrinsic apoptosis, disruption of autophagic flux, and cell cycle arrest at the G0/G1 phase. In in vivo mouse models, we found that FXT exhibits strong inhibitory activity against melanoma brain metastases and lung metastases. Our findings provide a foundation for future clinical exploration of FXT as a novel treatment strategy for melanoma, underscoring its ability to target both primary and metastatic lesions.

[Antidepressants as additional drugs for human brain gliomas]

Glioblastoma (GB) is the most aggressive malignant brain tumor. To date, there is no optimal treatment approach for this disease. Antidepressants with antitumor effects are one of the new therapeutic directions. A distinctive feature of these drugs is their approval for clinical practice in the treatment of depressive disorders.

OBJECTIVE

To analyze available literature data on mechanisms of antitumor action and advisability of antidepressants for GB.

MATERIAL AND METHODS

We reviewed the databases using the keywords «glioma», «antidepressants», «drug repurposing».

RESULTS

According to numerous preclinical studies, activity of antidepressants at the cellular level is aimed at enhancing apoptosis and autophagy, inhibiting the cell cycle, differentiating and/or maintaining the stem cell status, as well as migrating tumor cells.

CONCLUSION

Available data can substantiate further experimental and clinical studies, as well as searching for therapeutic combinations using antidepressants for the treatment of human gliomas.

Fabrication and Assessment of Diosgenin Encapsulated Stearic Acid Solid Lipid Nanoparticles for Its Anticancer and Antidepressant Effects Using in vitro and in vivo Models

Inflammatory cascade plays a pivotal role in the onset and progression of major depressive disorder (MDD) and glioblastoma multiforme (GBM). Therefore, questing natural compounds with anti-inflammatory activity such as diosgenin can act as a double-edged sword targeting cancer and cancer-induced inflammation simultaneously. The blood–brain barrier limits the therapeutic efficiency of the drugs against intracranial pathologies including depression and brain cancers. Encapsulating a drug molecule in lipid nanoparticles can overcome this obstacle. The current study has thus investigated the anticancer and antidepressant effect of Tween 80 (P80) coated stearic acid solid lipid nanoparticles (SLNPs) encapsulating the diosgenin. Physio-chemical characterizations of SLNPs were performed to assess their stability, monodispersity, and entrapment efficiency. In vitro cytotoxic analysis of naked and drug encapsulated SLNPs on U-87 cell line indicated diosgenin IC₅₀ value to be 194.4 μM, while diosgenin encapsulation in nanoparticles slightly decreases the toxicity. Antidepressant effects of encapsulated and non-encapsulated diosgenin were comprehensively evaluated in the concanavalin-A–induced sickness behavior mouse model. Behavior test results indicate that diosgenin and diosgenin encapsulated nanoparticles significantly alleviated anxiety-like and depressive behavior. Diosgenin incorporated SLNPs also improved grooming behavior and social interaction as well as showed normal levels of neutrophils and leukocytes with no toxicity indication. In conclusion, diosgenin and diosgenin encapsulated solid lipid nanoparticles proved successful in decreasing in vitro cancer cell proliferation and improving sickness behavioral phenotype and thus merit further exploration.

Fluoxetine as an anti-inflammatory therapy in SARS-CoV-2 infection

Hyperinflammatory response caused by infections such as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) increases organ failure, intensive care unit admission, and mortality. Cytokine storm in patients with Coronavirus Disease 2019 (COVID-19) drives this pattern of poor clinical outcomes and is dependent upon the activity of the transcription factor complex nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappaB) and its downstream target gene interleukin 6 (IL6) which interacts with IL6 receptor (IL6R) and the IL6 signal transduction protein (IL6ST or gp130) to regulate intracellular inflammatory pathways. In this study, we compare transcriptomic signatures from a variety of drug-treated or genetically suppressed (i.e. knockdown) cell lines in order to identify a mechanism by which antidepressants such as fluoxetine demonstrate non-serotonergic, anti-inflammatory effects. Our results demonstrate a critical role for IL6ST and NF-kappaB Subunit 1 (NFKB1) in fluoxetine's ability to act as a potential therapy for hyperinflammatory states such as asthma, sepsis, and COVID-19.

Induction of apoptosis through extrinsic/intrinsic pathways and suppression of ERK/NF-κB signalling participate in anti-glioblastoma of imipramine

Glioblastomas are the most aggressive type of brain tumour, with poor prognosis even after standard treatment such as surgical resection, temozolomide and radiation therapy. The overexpression of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in glioblastomas is recognized as an important treatment target. Thus, an urgent need regarding glioblastomas is the development of a new, suitable agent that may show potential for the inhibition of extracellular signal-regulated kinase (ERK)/NF-κB-mediated glioblastoma progression. Imipramine, a tricyclic antidepressant, has anti-inflammatory actions against inflamed glial cells; additionally, imipramine can induce glioblastoma toxicity via the activation of autophagy. However, whether imipramine can suppress glioblastoma progression via the induction of apoptosis and blockage of ERK/NF-κB signalling remains unclear. The main purpose of this study was to investigate the effects of imipramine on apoptotic signalling and ERK/NF-κB-mediated glioblastoma progression by using cell proliferation (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide [MTT] assay), flow cytometry, Western blotting, and cell invasion/migration assay analysis in vitro. The ERK and NF-κB inhibitory capacity of imipramine is detected by NF-κB reporter gene assay and Western blotting. Additionally, a glioblastoma-bearing animal model was used to validate the therapeutic efficacy and general toxicity of imipramine. Our results demonstrated that imipramine successfully triggered apoptosis through extrinsic/intrinsic pathways and suppressed the invasion/migration ability of glioblastoma cells. Furthermore, imipramine effectively suppressed glioblastoma progression in vivo via the inhibition of the ERK/NF-κB pathway. In summary, imipramine is a potential anti-glioblastoma drug which induces apoptosis and has the capacity to inhibit ERK/NF-κB signalling.

Identification of a Tumor Microenvironment-Related Eight-Gene Signature for Predicting Prognosis in Lower-Grade Gliomas

Lower-grade gliomas (LrGG), characterized by invasiveness and heterogeneity, remain incurable with current therapies. Clinicopathological features provide insufficient information to guide optimal individual treatment and cannot predict prognosis completely. Recently, an increasing amount of studies indicate that the tumor microenvironment plays a pivotal role in tumor malignancy and treatment responses. However, studies focusing on the tumor microenvironment (TME) of LrGG are still limited. In this study, taking advantage of the currently popular computational methods for estimating the infiltration of tumor-associated normal cells in tumor samples and using weighted gene co-expression network analysis, we screened the co-expressed gene modules associated with the TME and further identified the prognostic hub genes in these modules. Furthermore, eight prognostic hub genes (ARHGDIB, CLIC1, OAS3, PDIA4, PARP9, STAT1, TAP2, and TAGLN2) were selected to construct a prognostic risk score model using the least absolute shrinkage and selection operator method. Univariate and multivariate Cox regression analysis demonstrated that the risk score was an independent prognostic factor for LrGG. Moreover, time-dependent ROC curves indicated that our model had favorable efficiency in predicting both short- and long-term prognosis in LrGG patients, and the stratified survival analysis demonstrated that our model had prognostic value for different subgroups of LrGG patients. Additionally, our model had potential value for predicting the sensitivity of LrGG patients to radio- and chemotherapy. Besides, differential expression analysis showed that the eight genes were aberrantly expressed in LrGG compared to normal brain tissue. Correlation analysis revealed that the expression of the eight genes was significantly associated with the infiltration levels of six types of immune cells in LrGG. In summary, the TME-related eight-gene signature was significantly associated with the prognosis of LrGG patients. They might act as potential prognostic biomarkers for LrGG patients, offer better stratification for future clinical trials, and be candidate targets for immunotherapy, thus deserving further investigation.

MGMT is down-regulated independently of promoter DNA methylation in rats with all-trans retinoic acid-induced spina bifida aperta

O6-methylguanine DNA methyltransferase (MGMT), a DNA repair enzyme, has been reported in some congenital malformations, but it is less frequently reported in neural tube defects. This study investigated MGMT mRNA expression and methylation levels in the early embryo and in different embryonic stages, as well as the relationship between MGMT and neural tube defects. Spina bifida aperta was induced in rats by a single intragastric administration of all-trans retinoic acid on embryonic day (E) 10, whereas normal control rats received the same amount of olive oil on the same embryonic day. DNA damage was assessed by detecting γ-H2A.X in spina bifida aperta rats. Real time-polymerase chain reaction was used to examine mRNA expression of MGMT in normal control and spina bifida aperta rats. In normal controls, the MGMT mRNA expression decreased with increasing embryonic days, and was remarkably reduced from E11 to E14, reaching a minimum at E18. In the spina bifida aperta model, γ-H2A.X protein expression was increased, and mRNA expression of MGMT was markedly decreased on E14, E16, and E18. Bisulfite sequencing polymerase chain reaction for MGMT promoter methylation demonstrated that almost all CpG sites in the MGMT promoter remained unmethylated in both spina bifida aperta rats and normal controls, and there was no significant difference in methylation level between the two groups on either E14 or E18. Our results show that DNA damage occurs in spina bifida aperta rats. The mRNA expression of MGMT is downregulated, and this downregulation is independent of promoter DNA methylation.

Down-regulation of ABCE1 inhibits temozolomide resistance in glioma through the PI3K/Akt/NF-κB signaling pathway

The ATP binding cassette (ABC) E1 (ABCE1), a member of the ABC family, was originally described as the RNase L inhibitor. Through forming a heterodimer with RNase L, ABCE1 participates in the negative regulation of the 2-5A/RNase L system and thus mediates a wide range of biological functions. Recent evidence has shown the new roles of ABCE1 in tumorigenesis. However, there have been no investigations on the specific effect of ABCE1 on glioma. In the present study, we examined the expression pattern and possible role of ABCE1 in glioma. Our study demonstrated that ABCE1 was up-regulated in glioma tissues and cell lines. Down-regulation of ABCE1 inhibited temozolomide (TMZ) resistance of glioma cells in vitro and in vivo In addition, we found that the PI3K/Akt/NF-κB pathway was involved in ABCE1-mediated chemoresistance of glioma cells. Taken together, our study suggested ABCE1 as a promising target for glioma chemotherapy.

Forkhead box K2 inhibits the proliferation, migration, and invasion of human glioma cells and predicts a favorable prognosis

Purpose

Forkhead box K2 (FOXK2) is a member of the forkhead box family of transcription factors. Recently, researchers discovered that overexpression of FOXK2 inhibits the proliferation and metastasis of breast cancer, non-small cell lung cancer, and colorectal cancer, and is related to the clinical prognosis. However, in hepatocellular carcinoma, FOXK2 results in the opposite phenotypes. Currently, the contribution of FOXK2 to glioma pathogenesis is not clear.

Patients and methods

We evaluated the expression of FOXK2 in 151 glioma patients using immunohistochemistry assays. The associations among the expression of FOXK2, clinicopathological parameters, and the prognosis of glioma patients were statistically analyzed. We downregulated and upregulated the level of FOXK2 in glioma cells by transfections with small interfering RNA and plasmids. Then, we investigated the effects on tumor cell behavior in vitro by Cell Counting Kit-8 assays, colony-formation assay, transwell assay, and the epithelial-to-mesenchymal transition (EMT) biomarker levels.

Results

The clinical data showed that expression of FOXK2 gradually decreased with increasing World Health Organization (WHO) grades and a low level of FOXK2 indicates a poor prognosis. FOXK2 expression is negatively correlated with Ki67 expression and the WHO degree but is not correlated with other clinicopathological parameters, including sex, age, Karnofsky Performance Status, tumor diameter, O-6-methylguanine-DNA methyltransferase, and glutathione S-transferase pi. FOXK2 knockdown enhances glioma cell proliferation, migration, invasion, and EMT process, and, in contrast, FOXK2 overexpression inhibits glioma cell proliferation, migration, invasion, and the EMT process.

Conclusion

Expression of FOXK2 gradually decreases with increasing WHO grades. FOXK2 inhibits tumor proliferation, migration, and invasion. FOXK2 is a critical mediator of the EMT process.

Pyrrolidine dithiocarbamate sensitizes U251 brain glioma cells to temozolomide via downregulation of MGMT and BCL-XL

The current study investigated the effect of pyrrolidine dithiocarbamate (PDTC) on the proliferation, apoptosis, cell cycle and sensitivity to temozolomide (TMZ) of the U251 glioma cell line. Proliferation, apoptosis and cell cycle analysis of U251 cells following treatment with PDTC and TMZ was determined by an MTT assay and flow cytometry, respectively. The mRNA and protein expression levels of O-6-methylguanine-DNA methyltransferase (MGMT), B-cell lymphoma extra-large (BCL-XL) and survivin were further determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting analysis. The results revealed that treatment with TMZ, PDTC and TMZ + PDTC significantly inhibited cell proliferation, induced apoptosis and contributed to cell cycle arrest in U251 cells. A combination of PDTC and TMZ induced the highest rates of proliferation inhibition and apoptosis. PDTC treatment markedly reduced the expression levels of MGMT, BCL-XL and survivin. The expression levels of MGMT and BCL-XL, were significantly upregulated by TMZ but not by combination treatment of TMZ and PDTC. The results of the present study suggest that treatment with PDTC inhibits cell proliferation, induces apoptosis and cell cycle arrest, and enhances sensitivity to TMZ in U251 cells, which is partly induced by downregulation of MGMT and BCL-XL.

Fluoxetine synergizes with temozolomide to induce the CHOP-dependent endoplasmic reticulum stress-related apoptosis pathway in glioma cells

Although temozolomide (TMZ) is the most effective chemotherapy agent for glioma, chemotherapy resistance has limited its clinical use. Fluoxetine (FLT), which is widely used in cancer-related depression, has exhibited potent anticancer properties in different cancer cell types. The aim of this study was i) to evaluate the antitumor mechanism of FLT, and ii) to further evaluate the effects of a combination of FLT and TMZ on glioma cells. Glioma cell lines were exposed to FLT and/or TMZ. Cell viability and apoptosis were examined by CCK-8 assay, flow cytometry and caspase-3 activity assay, respectively. The expression of endoplasmic reticulum-stress (ERS) apoptosis-related proteins was measured using real-time PCR and western blotting. Synergism between the two drugs was evaluated by the combination index (CI) through CompuSyn software. FLT significantly and dose-dependently inhibited the proliferation of various glioma cell lines, and rat glioma C6 cells had a highly sensitive response to the addition of FLT. FLT treatment increased the early apoptosis rate, induced typical apoptotic morphology in the C6 cells and activated caspase-3 with no change in the mitochondrial membrane potential. Further study showed that FLT activated the ERS marker, CHOP. This induction was associated with activation of the PERK-eIF2α-ATF4 and ATF6 cascade. Concomitantly, GADD34, a downstream molecule of CHOP, was also increased. Combined FLT and TMZ treatment showed a synergistic cytotoxic effect in the C6 glioma cells. Knockdown of CHOP expression abolished the synergistic effect of FLT and TMZ in the C6 cells, which suggests that FLT may sensitize glioma cells to TMZ through activation of the CHOP-dependent apoptosis pathway. These results revealed that FLT induced glioma cell apoptosis and sensitized glioma cells to TMZ through activation of the CHOP-dependent apoptosis pathway. The present study provides a primary basis for using the combination of these drugs in patients with advanced glioma.