IκB-α: At the crossroad between oncogenic and tumor-suppressive signals

The molecular mechanism of NF-κB dysregulation across different subtypes of renal cell carcinoma

BACKGROUND

The nuclear factor kappa B (NF-κB) is a critical pathway that regulates various cellular functions, including immune response, proliferation, growth, and apoptosis. Furthermore, this pathway is tightly regulated to ensure stability in the presence of immunogenic triggers or genotoxic stimuli. The lack of control of the NF-κB pathway can lead to the initiation of different diseases, mainly autoimmune diseases and cancer, including Renal cell carcinoma (RCC). RCC is the most common type of kidney cancer and is characterized by complex genetic composition and elusive molecular mechanisms.

AIM OF REVIEW

The current review summarizes the mechanism of NF-κB dysregulation in different subtypes of RCC and its impact on pathogenesis.

KEY SCIENTIFIC CONCEPT OF REVIEW

This review highlights the prominent role of NF-κB in RCC development and progression by driving the expression of multiple genes and interplaying with different pathways, including the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway. In silico analysis of RCC cohorts and molecular studies have revealed that multiple NF-κB members and target genes are dysregulated. The dysregulation includes receptors such as TLR2, signal-transmitting members including RelA, and target genes, for instance, HIF-1α. The lack of effective regulatory mechanisms results in a constitutively active NF-κB pathway, which promotes cancer growth, migration, and survival. In this review, we comprehensively summarize the role of dysregulated NF-κB-related genes in the most common subtypes of RCC, including clear cell RCC (ccRCC), chromophobe RCC (chRCC), and papillary RCC (PRCC).

Synbiotics containing sea buckthorn polysaccharides ameliorate DSS-induced colitis in mice via regulating Th17/Treg homeostasis through intestinal microbiota and their production of BA metabolites and SCFAs

Inflammatory Bowel Disease (IBD) is a chronic condition whose incidence has been rising globally. Synbiotic (SYN) is an effective means of preventing IBD. This study investigated the preventive effects and potential biological mechanisms of SYN (Bifidobacterium longum, Lactobacillus acidophilus, and sea buckthorn polysaccharides) on DSS-induced colitis in mice. The results indicated that dietary supplementation with SYN has a significant improvement effect on DSS mice. SYN ameliorated disease activity index (DAI), colon length, and intestinal barrier permeability in mice. In addition, RT-qPCR results indicated that after SYN intervention, the expression levels of pro-inflammatory factors (IL-6, IL-1β, TNF-α, and IL-17F) and transcription factor RORγt secreted by Th17 cells were significantly reduced, and the expression levels of anti-inflammatory factors (IL-10 and TGF-β) and transcription factor Foxp3 secreted by Treg cells were robustly increased. 16S rDNA sequencing analysis revealed that key intestinal microbiota related to Th17/Treg balance (Ligilactobacillus, Lactobacillus, Bacteroides, and Akkermansia) was significantly enriched. At the same time, a significant increase in microbial metabolites SCFAs and BAs was observed. We speculate that SYN may regulate the Th17/Treg balance by restructuring the structure and composition of the intestinal microbiota, thereby mitigating DSS-induced colitis.

Long-term exposure to ambient air pollution and risk of leukemia and lymphoma in a pooled European cohort

Leukemia and lymphoma are the two most common forms of hematologic malignancy, and their etiology is largely unknown. Pathophysiological mechanisms suggest a possible association with air pollution, but little empirical evidence is available. We aimed to investigate the association between long-term residential exposure to outdoor air pollution and risk of leukemia and lymphoma. We pooled data from four cohorts from three European countries as part of the "Effects of Low-level Air Pollution: a Study in Europe" (ELAPSE) collaboration. We used Europe-wide land use regression models to assess annual mean concentrations of fine particulate matter (PM2.5), nitrogen dioxide (NO2), black carbon (BC) and ozone (O3) at residences. We also estimated concentrations of PM2.5 elemental components: copper (Cu), iron (Fe), zinc (Zn); sulfur (S); nickel (Ni), vanadium (V), silicon (Si) and potassium (K). We applied Cox proportional hazards models to investigate the associations. Among the study population of 247,436 individuals, 760 leukemia and 1122 lymphoma cases were diagnosed during 4,656,140 person-years of follow-up. The results showed a leukemia hazard ratio (HR) of 1.13 (95% confidence intervals [CI]: 1.01-1.26) per 10 μg/m3 NO2, which was robust in two-pollutant models and consistent across the four cohorts and according to smoking status. Sex-specific analyses suggested that this association was confined to the male population. Further, the results showed increased lymphoma HRs for PM2.5 (HR = 1.16; 95% CI: 1.02-1.34) and potassium content of PM2.5, which were consistent in two-pollutant models and according to sex. Our results suggest that air pollution at the residence may be associated with adult leukemia and lymphoma.

Decreased TAX1BP1 participates in systemic lupus erythematosus by regulating monocyte/macrophage function

Systemic lupus erythematosus (SLE) involves disorders of innate and adaptive immune pathways. Tax1-binding protein 1 (TAX1BP1) modulates the production of antibodies in B cells and the T-cell cycle by regulating the NF-κB signaling pathway. However, the potential association of TAX1BP1 with SLE and its role in monocytes/macrophages have not been fully elucidated. In this study, we utilized whole-exome sequencing (WES) in combination with Sanger sequencing and identified 16 gene mutations, including in TAX1BP1, in an SLE family. TAX1BP1 protein expression with western blotting detection was reduced in SLE patients and correlated with disease activity negatively. Furthermore, RNA sequencing and 4D Label-Free Phosphoproteomic analysis were employed to characterize the transcriptome and phosphoproteome profiles in THP-1 and THP-1-differentiated M1 macrophages with TAX1BP1 knockdown. Silencing of TAX1BP1 in THP-1 and THP-1-differentiated M1 macrophages led to an increase in cluster of differentiation 80 (CD80) expression and differential changes in CD14 and CD16 expression, as assessed by flow cytometry. Additionally, western blot analysis showed that knockdown of TAX1BP1 led to a reduction in TRAF6 and p-p65 in THP-1-differentiated macrophages, with or without lipopolysaccharide (LPS) or tumor necrosis factor (TNF)-α stimulation. Taken together, our findings suggest that TAX1BP1 participates in SLE activity by regulating antigen presentation in monocytes and inflammatory responses in M1 macrophages.

Prediction of dual NF-κB/IκB inhibitors using an integrative in-silico approaches

Multiple lines of evidence indicate that the NF-κB signaling pathway plays a pivotal role in carcinogenesis; activation of NF-κB in cancer increases cell proliferation and suppresses apoptosis, both of which define tumor mass development. Inhibiting NF-κB leads to tumor suppression by blocking the IKK-α/β enzymes, thus inhibiting its translocation. Furthermore, protecting p65 from acetylation and phosphorylation inhibits NF-κB through its active site. Some small molecules are assumed to inhibit NF-κB and IκB function separately. This study took one of the previously reported NF-κB inhibitors (compound D4) as a promising lead and predicted some dual NF-κB and IκB inhibitors. We performed a virtual screening (VS) workflow on a library with 186,146 compounds with 75% similarity to compound D4 on both NF-κB and IκB proteins. A total of 186 compounds were extracted from three steps of VS 36 were common in both proteins. These compounds were subjected to the quantum polarized ligand docking to elect potent compounds with the highest binding affinity for NF-κB and IκB proteins. The MM-GBSA method calculates the lowest binding free energy for eight selected compounds. These analyses found three top-ranked compounds for each protein with suitable pharmacokinetics properties and higher in-silico inhibitory ability. In the last screening, compound CID_4969 was introduced to a molecular dynamics (MDs) simulation study as a common inhibitor for both proteins. The MDs confirmed the main interactions between the final elected compound and NF-κB/IκB proteins. Consequently, the presented computational approaches could be used for designing promising anti-cancer agents.Communicated by Ramaswamy H. Sarma.

Untapping the protective role of carotenoids against respiratory diseases

BACKGROUND

Recent studies revealed a substantial role of carotenoids to treat respiratory diseases. This review aimed to give an updated overview of the investigational evidence on the preventive properties of carotenoids against respiratory diseases both in vitro and in vivo along with their pathophysiology and mechanisms of action.

HYPOTHESIS

Carotenoids as a potential therapeutic class of bioactive compounds to treat respiratory diseases.

RESULTS

Carotenoids such as β-carotene, lycopene, crocin, bixin, lutein, and astaxanthin show beneficial effects against chronic lung diseases (e.g., asthma, emphysema, fibrosis, COPD, acute lung injury, and lung cancer). Moreover, in vitro and in vivo studies also supported the preventive role of carotenoids. These carotenoids showed a beneficial role by activation of the NRF2/HO-1 pathway and inhibition of the NF-кB, MAPK, JAK/STAT-3, and PI3K/AKT pathways. Additionally, epidemiological studies also showed that dietary intake of carotenoids lowers the risk of lung diseases.

CONCLUSION

Carotenoids may be used as drugs or can be given in combination with other drugs to prevent and treat respiratory diseases. Although in vitro and in vivo results are encouraging, further well-conducted randomized clinical trials are required to approve carotenoids as drug candidates.

Better Bioactivity, Cerebral Metabolism and Pharmacokinetics of Natural Medicine and Its Advanced Version

Currently, many people are afflicted by cerebral diseases that cause dysfunction in the brain and perturb normal daily life of people. Cerebral diseases are greatly affected by cerebral metabolism, including the anabolism and catabolism of neurotransmitters, hormones, neurotrophic molecules and other brain-specific chemicals. Natural medicines (NMs) have the advantages of low cost and low toxicity. NMs are potential treatments for cerebral diseases due to their ability to regulate cerebral metabolism. However, most NMs have low bioavailability due to their low solubility/permeability. The study is to summarize the better bioactivity, cerebral metabolism and pharmacokinetics of NMs and its advanced version. This study sums up research articles on the NMs to treat brain diseases. NMs affect cerebral metabolism and the related mechanisms are revealed. Nanotechnologies are applied to deliver NMs. Appropriate delivery systems (exosomes, nanoparticles, liposomes, lipid polymer hybrid nanoparticles, nanoemulsions, protein conjugation and nanosuspensions, etc.) provide better pharmacological and pharmacokinetic characteristics of NMs. The structure-based metabolic reactions and enzyme-modulated catalytic reactions related to advanced versions of NMs alter the pharmacological activities of NMs.

Shedding Light on NF-κB Functions in Cellular Organelles

NF-κB is diffusely recognized as a transcriptional factor able to modulate the expression of various genes involved in a broad spectrum of cellular functions, including proliferation, survival and migration. NF-κB is, however, also acting outside the nucleus and beyond its ability to binds to DNA. NF-κB is indeed found to localize inside different cellular organelles, such as mitochondria, endoplasmic reticulum, Golgi and nucleoli, where it acts through different partners in mediating various biological functions. Here, we discuss the relationship linking NF-κB to the cellular organelles, and how this crosstalk between cellular organelles and NF-κB signalling may be evaluated for anticancer therapies.

Transforming Growth Factor-Beta (TGF-β) Signaling in Cancer-A Betrayal Within

A ubiquitously expressed cytokine, transforming growth factor-beta (TGF-β) plays a significant role in various ongoing cellular mechanisms. The gain or loss-of-function of TGF-β and its downstream mediators could lead to a plethora of diseases includes tumorigenesis. Specifically, at the early onset of malignancy TGF-β act as tumour suppressor and plays a key role in clearing malignant cells by reducing the cellular proliferation and differentiation thus triggers the process of apoptosis. Subsequently, TGF-β at an advanced stage of malignancy promotes tumorigenesis by augmenting cellular transformation, epithelial-mesenchymal-transition invasion, and metastasis. Besides playing the dual roles, depending upon the stage of malignancy, TGF-β also regulates cell fate through immune and stroma components. This oscillatory role of TGF-β to fight against cancer or act as a traitor to collaborate and crosstalk with other tumorigenic signaling pathways and its betrayal within the cell depends upon the cellular context. Therefore, the current review highlights and understands the dual role of TGF-β under different cellular conditions and its crosstalk with other signaling pathways in modulating cell fate.

Anti-Cancer Effects of Zotarolimus Combined with 5-Fluorouracil Treatment in HCT-116 Colorectal Cancer-Bearing BALB/c Nude Mice

Zotarolimus is a semi-synthetic derivative of rapamycin and an inhibitor of mammalian target of rapamycin (mTOR) signaling. Currently, zotarolimus is used to prolong the survival time of organ grafts, but it is also a novel immunosuppressive agent with potent anti-proliferative activity. Here, we examine the anti-tumor effect of zotarolimus, alone and in combination with 5-fluorouracil, on HCT-116 colorectal adenocarcinoma cells implanted in BALB/c nude mice. Compared with the control mice, mice treated with zotarolimus or zotarolimus combined with 5-FU showed retarded tumor growth; increased tumor apoptosis through the enhanced expression of cleaved caspase 3 and extracellular signal-regulated kinase (ERK) phosphorylation; reduced inflammation-related factors such as IL-1β, TNF-α, and cyclooxygenase-2 (COX-2) protein; and inhibited metastasis-related factors such as CD44, epidermal growth factor receptor (EGFR), transforming growth factor β (TGF-β), and vascular endothelial growth factor (VEGF). Notably, mice treated with a combination of zotarolimus and 5-FU showed significantly retarded tumor growth, reduced tumor size, and increased tumor inhibition compared with mice treated with 5-FU or zotarolimus alone, indicating a strong synergistic effect. This in vivo study confirms that zotarolimus or zotarolimus combined with 5-FU can be used to retard colorectal adenocarcinoma growth and inhibit tumorigenesis. Our results suggest that zotarolimus may increase the chemo-sensitization of tumor cells. Therefore, zotarolimus alone and zotarolimus combined with 5-FU may be potential anti-tumor agents in the treatment of human colon adenocarcinoma. Future research on zotarolimus may lead to the development of new therapeutic strategies.

Long-term residential exposure to air pollution and Hodgkin lymphoma risk among adults in Denmark: a population-based case-control study

PURPOSE

The etiology of Hodgkin lymphoma (HL) is obscure. Research on air pollution and risk of HL provides inconsistent results. We aimed to investigate the association between long-term residential exposure to air pollution and risk of adult Hodgkin lymphoma in Denmark.

METHODS

We performed a nationwide register-based case-control study, including all (n = 2,681) Hodgkin lymphoma cases registered in the nationwide Danish Cancer Registry between 1989 and 2014. We randomly selected 8,853 age- and sex-matched controls from the entire Danish population using the Civil Registration System, and identified 20-year residential address history for all cases and controls. We modeled outdoor air pollution concentrations at all these addresses using the high-resolution multiscale air pollution model system DEHM/UBM/AirGIS. We used conditional logistic regression to estimate odds ratios adjusted for individual and neighborhood level sociodemographic variables.

RESULTS

There was no association between 1, 5, 10, and 20 years' time-weighted average exposure to fine particles (PM_2.5), O₃, SO_2, NO_2, or the PM_2.5 constituents OC, NH₄, NO₃, and SO₄ and risk of Hodgkin lymphoma.

CONCLUSION

Residential exposure to ambient air pollution does not seem to increase the risk of developing Hodgkin lymphoma.

Anti-tumor Activity of Propofol: A Focus on MicroRNAs

BACKGROUND

MicroRNAs are endogenous, short, non-coding RNAs with the length as low as 20 to 25 nucleotides. These RNAs are able to negatively affect the gene expression at the post-transcriptional level. It has been demonstrated that microRNAs play a significant role in cell proliferation, cell migration, cell death, cell differentiation, infection, immune response, and metabolism. Besides, the dysfunction of microRNAs has been observed in a variety of cancers. So, modulation of microRNAs is of interest in the treatment of disorders.

OBJECTIVE

The aim of the current review is to investigate the modulatory effect of propofol on microRNAs in cancer therapy.

METHODS

This review was performed at PubMed, SCOPUS and Web of Science data-bases using keywords "propofol', "microRNA", "cancer therapy", "propofol + microRNA" and "propofol + miR".

RESULTS

It was found that propofol dually down-regulates/upregulates microRNAs to exert its antitumor activity. In terms of oncogenesis microRNAs, propofol exert an inhibitory effect, while propofol significantly enhances the expression of oncosuppressor microRNAs.

CONCLUSION

It seems that propofol is a potential modulator of microRNAs and this capability can be used in the treatment of various cancers.

Hsa_circ_0056558 regulates cyclin-dependent kinase 6 by sponging microRNA-1290 to suppress the proliferation and differentiation in ankylosing spondylitis

The aims of this study was to investigate the influences of hsa_circ_0056558/miR-1290/CDK6 axis in ankylosing spondylitis (AS). The differentially expressed has_circ_0056558 and miR-1290 in AS tissue were analysed based on RNA-seq data and microarray data, respectively. qRT-PCR was performed for detection of relative expression levels of hsa_circ_0056558, miR-1290, CDK6, osteogenic differentiation markers (Runx2 and Osterix) and other inflammatory factors (TNF-α, IL-1β, and IL-6). Western blotting analysis was conducted to test the protein levels of CDK6, osteogenic differentiation markers (Runx2 and Osterix), and PI3K/AKT/NF-κB pathway-associated proteins. CCK8 assay and flow cytometry were conducted to determine cell proliferation and cell apoptotic ability, respectively. Targeted relationships were predicted by bioinformatic analysis and verified by dual-luciferase reporter assay. The differentiation of fibroblast cells was analysed by alkaline phosphatase (ALP) activity assay. Our findings revealed that the expression levels of both circ_0056558 and CDK6 in AS tissue were significantly higher than that in normal samples. Besides, hsa_circ_0056558 could suppress cell proliferation and differentiation by facilitating CDK6 expression and suppressing miR-1290 expression in AS. Over-expression of miR-1290 negatively regulated CDK6 expression to enhance cell proliferation. The protein levels of p-AKT, p-NF-κB p65, and p-IκBα were promoted by hsa_circ_0056558 or CDK6 over-expression while suppressed by miR-1290 up-regulation. In conclusion, our study demonstrated that hsa_circ_0056558 and CDK6 suppressed cell proliferation and differentiation while enhanced cell apoptosis by competitive binding to miR-1290 in AS, which might be possibly achieved by PI3K/AKT/NF-κB pathway, providing us novel therapeutic strategy for AS.

The Promising Effects of Astaxanthin on Lung Diseases

Astaxanthin (ASX) is a naturally occurring xanthophyll carotenoid. Both in vitro and in vivo studies have shown that it is a potent antioxidant with anti-inflammatory properties. Lung cancer is the leading cause of cancer death worldwide, whereas other lung diseases such as chronic obstructive pulmonary disease, emphysema, and asthma are of high prevalence. In the past decade, mounting evidence has suggested a protective role for ASX against lung diseases. This article reviews the potential role of ASX in protecting against lung diseases, including lung cancer. It also summarizes the underlying molecular mechanisms by which ASX protects against pulmonary diseases, including regulating the nuclear factor erythroid 2-related factor/heme oxygenase-1 pathway, NF-κB signaling, mitogen-activated protein kinase signaling, Janus kinase-signal transducers and activators of transcription-3 signaling, the phosphoinositide 3-kinase/Akt pathway, and modulating immune response. Several future directions are proposed in this review. However, most in vitro and in vivo studies have used ASX at concentrations that are not achievable by humans. Also, no clinical trials have been conducted and/or reported. Thus, preclinical studies with ASX treatment within physiological concentrations as well as human studies are required to examine the health benefits of ASX with respect to lung diseases.

Differential behavior of NF-κB, IκBα and EGFR during the renal carcinogenic process in an experimental model in vivo

Renal cell carcinoma (RCC) is the most common type of cancer of the adult kidney. It is generally asymptomatic even at advanced stages, so opportune diagnosis is rare, making it almost impossible to study this cancer at its early stages. RCC tumors induced by ferric nitrilotriacetate (FeNTA) in rats histologically correspond to the human clear cell RCC subtype (ccRCC) and the exposure to this carcinogen during either one or two months leads to different early stages of neoplastic development. High levels of nuclear factor kappa B (NF-κB) and epidermal growth factor receptor (EGFR) as well as low levels of NF-κB inhibitor alpha (IκBα) are frequent in human RCC, but their status in FeNTA-induced tumors and their evolution along renal carcinogenesis is unclear. On this basis, in the present study NF-κB, IκBα and EGFR behavior was analyzed at different stages of the experimental renal carcinogenesis model. Similar to patients with RCC, neoplastic tissue showed high levels of p65, one of the predominant subunits of NF-κB in ccRCC and of EGFR (protein and mRNA), as well as a decrease in the levels of NF-κB's main inhibitor, IκBα, resulting in a classic oncogenic combination. Conversely, different responses were observed at early stages of carcinogenesis. After one month of FeNTA-exposure, NF-κB activity and EGFR levels augmented; but unexpectedly, IκBα also did. While after two months, NF-κB activity diminished, but EGFR and IκBα levels remained elevated. In conclusion, FeNTA-induced tumors and RCC human neoplasms are analogues regarding to the classic NF-κB, IκBα and EGFR behavior, and distinctive non-conventional combination of changes is developed at each early stage studied. The results obtained suggest that the dysregulation of the analyzed molecules could be related to different signaling pathways and therefore, to particular effects depending on the phase of the carcinogenic process.

trans-Cinnamaldehyde Reverses Depressive-Like Behaviors in Chronic Unpredictable Mild Stress Rats by Inhibiting NF-κB/NLRP3 Inflammasome Pathway

trans-Cinnamaldehyde (TCA) is the main active component extracted from Cinnamomum cassia (C. cassia), which has many pharmacological effects, such as anti-inflammation, lowering blood glucose, and improving nerve function. However, there is no report of TCA in the treatment of depression. The purpose of this study was to investigate the antidepressant-like effect of TCA and the mechanism of NF kappa B (NF-κB) pathway and NLRP3 inflammasome inhibition by TCA. We divided 40 rats into the control group, CUMS group, FLU group, and the TCA group. The activation of the NF-κB pathway and NLRP3 inflammasome in prefrontal cortex and hippocampus of rats in each group was observed. After the treatments with FLU and TCA, the sucrose consumptions in rats increased significantly and the immobility time in forced swimming was decreased significantly compared to the CUMS group. The expression of TLR4, NF-κB-1, p-p65, TNF-α, NLRP3, ASC, caspase-1, IL-1β, and IL-18 proteins in prefrontal cortex and hippocampus was decreased, and the expression of IL-1β, IL-18, and TNF-α in serum was downregulated compared to the CUMS group. Similar to FLU, TCA reverses the depression-like behaviors in rats, which indicates that TCA has a significant antidepressant-like effect. The mechanism of the antidepressant property of TCA might be that it inhibits the activation of the NF-κB pathway and NLRP3 inflammasome in the prefrontal cortex and hippocampus of CUMS rats.

Transgelin-2 contributes to proliferation and progression of hepatocellular carcinoma via regulating Annexin A2

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors, but its pathogenesis is not clear. This study found that the expression of TAGLN2 mRNA and protein in HCC was higher than that in adjacent tissues. TCGA database analysis further confirmed this result, and found that the expression of TAGLN2 was positively correlated with the prognosis of HCC, suggesting that TAGLN2 may be a tumor promoter gene. Then the TAGLN2-Annexin A2 (ANXA2) interaction and NF-κB signaling pathway were further clarified during the invasion and metastasis of HCC. This mechanism provides a theoretical basis for further finding molecular targets and drug targets related to HCC metastasis.

Shikimic acid promotes estrogen receptor(ER)-positive breast cancer cells proliferation via activation of NF-κB signaling

Shikimic acid (SA), a widely-known hydroaromatic compound enriched in Bracken fern and Illicium verum (also known as Chinese star anise), increases the risk of gastric and esophageal carcinoma, nevertheless, the influence of SA on breast cancer remains indistinct. Herein we found that, with models in vitro, SA significantly promoted estrogen receptor(ER) positive cells proliferation and NF-κB activation was involved in it. Moreover, our data showed that IκBα, a critically endogenous inhibitor of NF-κB, was repressed. Subsequently, we found increase of miR-300 by SA treatment sand miR-300 could target IκBα mRNA. Additionally, inhibition of miR-300 abrogated the repression of IκBα by SA. As a result, miR-300 was also involved in NF-κB activation and breast cancer cells proliferation promotion due to SA exposure. Taken together, with ER-positive breast cancer cell models in vitro, MCF-7 and T47D, our results implied that SA promoted breast cancer cells proliferation via a miR-300-induced NF-κB dependent pathway controlling cell cycle proteins.

[Activation of nuclear factor-κB subunit p50/p65 enhances gefitinib resistance of lung adenocarcinoma H1650 cell line]

OBJECTIVE

To explore the intrinsic connection between activation of classical nuclear factor-κB (NF-κB) pathway and gefitinib resistance in human lung adenocarcinoma H1650 cells.

METHODS

Human lung adenocarcinoma H1650 cells were exposed to gefitinib continuously for 60 days to obtain resistant H1650 cells. The expressions of P-IκBα, P-p50 and P-p65 in the cytoplasm or nuclei were detected using Western blotting in human lung adenocarcinoma HCC827 cells, parental H1650 cells and gefitinib-resistant H1650 cells. The effects of gefitinib alone or in combination with PDTC on the survival rate and expressions of NF-κB P-p50 and P-p65 were compared among the 3 cell lines.

RESULTS

Gefitinib-resistant H1650 cells showed increased cytoplasmic and nuclear P-IκBα expressions. The expressions of P-p50 and P-p65 differed significantly among the 3 cell line, decreasing in the order of resistant H1650 cells, parental H1650 cells, and gefitinib sensitive HCC827 cell lines (P<0.05 or 0.01). Treatment with gefitinib alone resulted in a significantly lower cell inhibition rate in resistant H1650 cells than in the parental H1650 cells (P<0.05) and HCC827 cells (P<0.01). The resistant H1650 cells had a significantly higher expression of P-p50 and P-p65 than other two cell lines (P<0.05). In both the resistant and parental H1650 cells, gefitinib significantly lowered P-p50 and P-p65 expressions (P<0.05 or 0.01), and the combined treatment with gefitinib and PDTC significantly decreased the cell survival rate and further lowered the cytoplasmic and nuclear expressions of P-p50 and P-p65 (P<0.01 or 0.01).

CONCLUSION

The activation of classical NF-κB pathway is a key factor contributing to transformation of the parental H1650 cells into gefitinib-resistant cells. Gefitinib combined with PDTC can inhibit P-IκBα production and NF-κB P-p50 and P-p65 activation to suppress the survival of residual H1650 cells and the generation of gefitinib-resistant cells.