Clinical significance of the p53 pathway and associated gene therapy in non-small cell lung cancers

MDIG, a 2‑oxoglutarate‑dependent oxygenase, acts as an oncogene and predicts the prognosis of multiple types of cancer

Recent studies have indicated that mineral dust‑induced gene (MDIG) is an oncogene induced by environmental factors, which has a key role in the development and progression of various tumor types, through epigenetic modifications; however, there are no previous pan‑cancer analyses of MDIG. In the present study, a comprehensive pan‑cancer analysis of MDIG was performed using public databases. The results demonstrated that MDIG was upregulated in tumor tissue samples compared with normal tissue, that it was present in all cancer cell lines and it was closely associated with the prognosis of patients with different tumor types. Furthermore, MDIG expression was closely associated with the immunological characteristics of the tumor microenvironment (TME), such as the frequency of tumor‑infiltrating immune cells, TME‑relevant signatures, immunostimulatory genes, immune checkpoint genes, chemokine receptor genes, tumor mutational burden and microsatellite instability. In parallel, high expression of MDIG was associated with improved overall survival of patients and this was verified in a cohort of patients who had received anti‑programmed cell death 1 ligand 1 treatment. Furthermore, high expression of MDIG led to multiple drug resistance in The Cancer Genome Atlas‑lung adenocarcinoma cohort. In addition, gene set variant analysis and gene set enrichment analysis indicated that MDIG was involved in cell cycle regulation. In vitro experiments suggested that MDIG promoted cell proliferation through the mTOR complex 2/Akt and pyruvate dehydrogenase kinase 1/Akt signaling pathways. In summary, the present study suggests that MDIG may be a prognostic biomarker and therapeutic target for various cancer types.

Identification of key candidate tumor biomarkers in non-small-cell lung cancer by in silico analysis

Lung cancer is a common malignancy worldwide. The aim of the present study was to investigate differentially expressed genes (DEGs) between non-small-cell lung cancer (NSCLC) and normal lung tissue, and to reveal the potential molecular mechanism underlying NSCLC. The Gene Expression Omnibus database was used to obtain three gene expression profiles (GSE18842, GSE30219 and GSE33532). DEGs were obtained by GEO2R. Gene Ontology and pathway enrichment analyses were performed for DEGs in the Database for Annotation, Visualization and Integrated Discovery. A protein-protein interaction (PPI) network of DEGs was constructed and analyzed using the Search Tool for the Retrieval of Interacting Genes/Proteins database and Cytoscape software. A survival analysis was performed and protein expression levels of DEGs in human NSCLC were analyzed in order to determine clinical significance. A total of 764 DEGs were identified, consisting of 428 upregulated and 336 downregulated genes in NSCLC tissues compared with normal lung tissues, which were enriched in the 'cell cycle', 'cell adhesion molecules', 'p53 signaling pathway', 'DNA replication' and 'tight junction'. A PPI network of DEGs consisting of 51 nodes and 192 edges was constructed. The top 10 genes were identified as hub genes from the PPI network. High expression of 4 of the 10 hub genes was associated with worse overall survival rate in patients with NSCLC, including CDK1, PLK1, RAD51 and RFC4. In conclusion, the present study aids in improving the current understanding of aberrant gene expression between NSCLC tissues and normal lung tissues underlying tumorgenesis in NSCLC. Identified hub genes can be used as a tumor marker for diagnosis and prognosis or as a drug therapy target in NSCLC.

PTEN inhibits non-small cell lung cancer cell growth by promoting G0/G1 arrest and cell apoptosis

Non-small cell lung cancer (NSCLC) is a major type of human lung cancer and the primary cause of cancer-associated cases of mortality worldwide. Phosphatase and tensin homolog (PTEN) is a potent tumor suppressor gene in various human cancer types. The aim of the current study was to explore the role of PTEN and its associated regulatory mechanisms in NSCLC. Firstly, the expression of PTEN was detected using western blotting in a variety of NSCLC cell lines. The results revealed that compared with normal control cells, PTEN levels were significantly decreased in NSCLC cell lines (P<0.01). Short hairpin (sh)RNAs specific to PTEN were also used to knockdown endogenous PTEN in NSCLC cells. The results indicated that cell viability was significantly increased in PTEN-knockdown cells compared with those transfected with negative control shRNA (P<0.01). Conversely, overexpression of PTEN in A549 and SK-MES-1 cells significantly decreased the optical density of NSCLC cells (P<0.01). Flow cytometry was used to investigate the cell cycle; the results revealed that PTEN knockdown significantly increased the percentage of cells at G₀/G₁ phase (P<0.01) and decreased the number of cells at S phase (P<0.01). The molecular mechanism was further explored using western blotting and the results demonstrated that PTEN overexpression increased the levels of cleaved caspase-3 (P<0.01). These results suggest that PTEN may be a potential target gene for gene therapy in patients with NSCLCs.

Positioning of proteasome inhibitors in therapy of solid malignancies

Targeting of the protein degradation pathway, in particular, the ubiquitin-proteasome system, has emerged as an attractive novel cancer chemotherapeutic modality. Although proteasome inhibitors have been most successfully applied in the treatment of hematological malignancies, they also received continuing interest for the treatment of solid tumors. In this review, we summarize the current positioning of proteasome inhibitors in the treatment of common solid malignancies (e.g., lung, colon, pancreas, breast, and head and neck cancer), addressing topics of their mechanism(s) of action, predictive factors and molecular mechanisms of resistance.

Combined bortezomib-based chemotherapy and p53 gene therapy using hollow mesoporous silica nanospheres for p53 mutant non-small cell lung cancer treatment

Hollow mesoporous silica nanospheres (HMSN)-based co-delivery of bortezomib (BTZ) and the tumor suppressor gene p53 was developed for p53 signal impaired NSCLC therapy.

Dioscin suppresses hepatocellular carcinoma tumor growth by inducing apoptosis and regulation of TP53, BAX, BCL2 and cleaved CASP3

BACKGROUND

Hepatocellular carcinoma (HCC) is the most commonly diagnosed malignancy of the liver, occurs frequently in the setting of chronic liver injury. Although multiple therapeutic approaches are available, the prognosis of patients with HCC remains poor. Dioscin is a natural steroid saponin that presents in various plants. The anti-cancer and anti-fibrotic effects have been extensively reported. However, the effect of dioscin on HCC remains unclear. We aimed to investigate the anti-HCC properties of dioscin in vitro and in vivo.

METHODS

MTT (3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyl-tetrazolium bromide) assay was used to analyze the growth inhibition activity of Dioscin in human cell lines, Bel-7402, HepG2, Lovo, and EAhy926. Antitumor activity through induction of apoptosis was evaluated by flow cytometry using Annexin-V and propidium iodide (PI) staining, laser scanning confocal microscopy (LSCM) analysis with Hochest33342 and PI labeling, and DNA fragmentation analysis. The expression of apoptosis-related proteins tumor protein p53 (TP53), BCL2-associated X protein (BAX), B-Cell CLL/Lymphoma 2 (BCL2) and Caspase 3 (CASP3) was measured by Western blot. Nude mice bearing Bel-7402 were administered intraperitoneally at different doses of dioscin and 5-FU (5-Fluorouracil) treatment was used as a control. Tumor volume and tumor weight of each mouse were then measured.

RESULTS

We demonstrated that Dioscin inhibited proliferation of HCC cell lines in a dose-dependent manner. Dioscin also significantly induced morphological changes during death by apoptosis and increased DNA damage of Bel-7402 cells. Moreover, we demonstrated that Dioscin displayed anticancer activity via up-regulating expression of TP53, BAX and CASP3 protein, as well as down-regulating BCL2 in Bel-7402 cells. Notably, the in vivo anticancer activity of Dioscin was further assessed and achieved greater inhibition efficiency at the concentration increased to 24mg/kg/day than 5-FU at dose of 10mg/kg/day in nude mice bearing Bel-7402 cells.

CONCLUSIONS

Dioscin inhibited tumor growth via inducing apoptosis, which was accompanied by altered expression of apoptotic pathway proteins, such as TP53, BAX, BCL2 and CASP3. Our findings indicate that further evaluation of dioscin as a novel therapeutic approach for HCC is warranted.

Complex analysis of the p53 tumor suppressor in lung carcinoma

Lung cancer is the leading cause of cancer-related deaths worldwide. The p53 tumor suppressor is a transcription factor controlling expression of its target genes in response to various stress stimuli. Mutations of the TP53 gene occur very frequently in lung carcinomas and they play an important role in both oncogenic transformation of lung epithelial cells and lung carcinoma progression. We determined the TP53 status in 42 samples of squamous cell lung carcinoma (SQCC) and 56 samples of lung adenocarcinoma (AC) by the functional analysis FASAY and its variant called split assay. Altogether, we detected 64 TP53 mutations in 63 patients and analyzed them by cDNA and gDNA sequencing. The TP53 mutations were found in 76.2% (32/42) of SQCC cases, and 55.4% (31/56) of ACs. Immunoblotting revealed the p53 protein accumulation in 18 samples (42.9%) among SQCC cases and 19 samples (33.9%) among AC cases. Using fluorescence in situ hybridization we detected loss of the TP53-specific 17p13.3 locus in 23 from 41 analyzed SQCC samples (56.1%) and in 20 from 54 analyzed AC samples (37.0%). We did not find any statistically significant differences in overall and disease-free survival in relation to TP53 status.

Diallyl disulfide attenuated carbon ion irradiation-induced apoptosis in mouse testis through changing the ratio of Tap73/ΔNp73 via mitochondrial pathway

Diallyl disulfide (DADS), a major organosulfur compound derived from garlic, has various biological properties, including anti-cancer effects. However, the protective mechanism of DADS against radiation-induced mouse testis cell apoptosis has not been elucidated. In this study, the magnitude of radiation effects evoked by carbon ion irradiation was marked by morphology changes, significant rise in apoptotic cells, activation expression of p53, up regulation the ratio of pro-apoptotic Tap73/anti-apoptotic ΔNp73, as well as alterations of crucial mediator of the mitochondrial pathway. Interestingly, pretreatment with DADS attenuated carbon ion irradiation-induced morphology damages and apoptotic cells. Additionally, DADS elevated radiation-induced p53 and p21 expression, suggesting that p53 might be involved in the inhibition of cell cycle progression through up regulation of p21. Furthermore, administration with DADS prevented radiation-induced Tap73/ΔNp73 expression and consequently down regulated Bax/Bcl-2 ratio, cytochrome c release and caspase-3 expression, indicating that the balance between Tap73 and ΔNp73 had potential to activate p53 responsive genes. Thus, our results showed that radio protection effect of DADS on mouse testis is mediated by blocking apoptosis through changing the ratio of Tap73/ΔNp73 via mitochondrial pathway, suggesting that DADS could be used as a potential radio protection agent for the testis against heavy-ion radiation.

Synergistic cytotoxic effects of recombinant human adenovirus p53 and radiation at various time points in A549 lung adenocarcinoma cells

The aim of this study was to evaluate the effects of recombinant human adenovirus p53 (rAd-p53; Gendicine) transfection and radiation at various time points following transfection. Cytotoxic effects and p53 protein expression levels were analyzed. rAd-p53 containing the human wild-type p53 gene was introduced into the human lung adenocarcinoma cell line A549, and cells were irradiated with a single dose of 6 MeV 4 Gy β rays. According to the time interval between rAd-p53 transfection and radiotherapy (RT), A549-transfected rAd-p53 cells were divided into 5 groups: radiation administered immediately after transfection (0 h-RT) group, after 3 h group (3 h-RT), after 6 h group (6 h-RT), after 24 h group (24 h-RT) and after 48 h group (48 h-RT). Cells with rAd-p53 transfection alone (Ad-p53) and with empty adenovirus (Ad) were included as the two control groups. Following 72 h of transfection, cell viability and growth were analyzed using MTT assays and flow cytometry, and p53 protein expression was analyzed using western blot analysis. From 0 h-RT to 48 h-RT, cell viability gradually decreased, while percentage of apoptotic cells and p53 protein expression gradually increased. The cell viability suppression rates in the 6 h-RT, 24 h-RT and 48 h-RT groups were 56.7±5.4, 60.8±6.0 and 68.9±6.6, respectively, which were significantly greater compared to that of the Ad-p53 (40.8±4.7), 0 h-RT (45.0±3.5) and 3 h-RT groups (47.0±4.3). No statistically significant differences were observed in the cell viability suppression rates among the 6 h-RT, 24 h-RT and 48 h-RT groups (P>0.05). Similar changes were observed in the percentage of apoptotic cells. The p53 protein expression level in the 6 h-RT group (0.856±0.092) was higher compared to that in the 3 h-RT group (0.643±0.089) (t=2.882; P=0.045), but not significantly different from that of the 24 h-RT group (1.193±0.202). The cell viability suppression rate and percentage of apoptotic cells was positively correlated with p53 protein expression in the A549 cells (P<0.05). Radiation may inhibit or damage p53 protein expression at the early stage of rAd-p53 transfection. To sensitize tumor cells to irradiation and achieve maximal cytotoxic effects, it is recommended to conduct RT at least 6 h following transfection with rAd-p53.

The curcuminoid CLEFMA selectively induces cell death in H441 lung adenocarcinoma cells via oxidative stress

CLEFMA or 4-[3,5-bis(2-chlorobenzylidene-4-oxo-piperidine-1-yl)-4-oxo-2-butenoic acid] is a curcuminoid being developed as an anticancer drug. We recently reported that it potently inhibits proliferation of various cancer cells. In this project, we investigated the effect of CLEFMA on gene expression profile in H441 lung adenocarcinoma cells, and studied its mechanism of action. In microarray data, we observed a deregulation of genes involved in redox and glutamate metabolism. Based on the affected ontologies, we hypothesized that antiproliferative activity of CLEFMA could be a result of the induction of reactive oxygen species (ROS). We tested this hypothesis by determining the levels of glutathione (GSH) and ROS in H441 cells treated with CLEFMA. We observed a rapid depletion of intracellular GSH/GSSG ratio. Using a cell-permeable fluorogenic substrate, we found that CLEFMA significantly induced ROS in a time- and dose-dependent manner (p < 0.05). Flow-cytometry with a mitochondria-selective fluorescent reporter of ROS indicated that the CLEFMA-induced ROS was of mitochondrial origin. In contrast to the cancer cells, the normal lung fibroblasts (CCL-151) did not show any increase in ROS and were resistant to CLEFMA-induced cell death. Furthermore, the addition of antioxidants, such as catalase, superoxide dismutase and N-acetylcysteine, rescued cancer cells from CLEFMA-induced cell death. Gene expression pathway analysis suggested that a transcription factor regulator Nrf2 is a pivotal molecule in the CLEFMA-induced deregulation of redox pathways. The immunoblotting of Nrf2 showed that CLEFMA treatment resulted in phosphorylation and nuclear translocation of Nrf2 in a time-dependent fashion. Based on these results, we conclude that induction of ROS is critical for the antiproliferative activity of CLEFMA and the Nrf2-mediated oxidative stress response fails to salvage H441 cells.

CLEFMA-an anti-proliferative curcuminoid from structure-activity relationship studies on 3,5-bis(benzylidene)-4-piperidones

3,5-Bis(benzylidene)-4-piperidones are being advanced as synthetic analogs of curcumin for anti-cancer and anti-inflammatory properties. We performed structure-activity relationship studies, by testing several synthesized 3,5-bis(benzylidene)-4-piperidones for anti-proliferative activity in lung adenocarcinoma H441 cells. Compared to the lead compound 1, or 3,5-bis(2-fluorobenzylidene)-4-piperidone, five compounds were found to be more potent (IC(50) < 30 microM), and 16 compounds possessed reduced cell-killing efficacy (IC(50) > 50 microM). Based on the observations, we synthesized 4-[3,5-bis(2-chlorobenzylidene-4-oxo-piperidine-1-yl)-4-oxo-2-butenoic acid] (29 or CLEFMA) as a novel analog of 1. CLEFMA was evaluated for anti-proliferative activity in H441 cells, and was found to be several folds more potent than compound 1. We did not find apoptotic cell population in flow cytometry, and the absence of apoptosis was confirmed by the lack of caspase cleavage. The electron microscopy of H441cells indicated that CLEFMA and compound 1 induce autophagic cell death that was inhibited by specific autophagy inhibitor 3-methyladenine. The results suggest that the potent and novel curcuminoid, CLEFMA, offers an alternative mode of cell death in apoptosis-resistant cancers.

Not gene therapy, but genetic surgery-the right strategy to attack cancer

In this review, I will suggest to divide all the approaches united now under common term "gene therapy" into two broad strategies of which the first one uses the methodology of targeted therapy with all its characteristics, but with genes in the role of agents targeted at a certain molecular component(s) presumably crucial for cancer maintenance. In contrast, the techniques of the other strategy are aimed at the destruction of tumors as a whole using the features shared by all cancers, for example relatively fast mitotic cell division or active angiogenesis. While the first strategy is "true" gene therapy, the second one is more like genetic surgery when a surgeon just cuts off a tumor with his scalpel and has no interest in knowing delicate mechanisms of cancer emergence and progression. I will try to substantiate the idea that the last strategy is the only right one, and its simplicity is paradoxically adequate to the super-complexity of tumors that originates from general complexity of cell regulation, strongly disturbed in tumor cells, and especially from the complexity of tumors as evolving cell populations, affecting also their ecological niche formed by neighboring normal cells and tissues. An analysis of the most widely used for such a "surgery" suicide gene/prodrug combinations will be presented in some more details.

Rosiglitazone inhibits alpha4 nicotinic acetylcholine receptor expression in human lung carcinoma cells through peroxisome proliferator-activated receptor gamma-independent signals

We and others have shown previously that nicotine, a major component of tobacco, stimulates non-small cell lung carcinoma (NSCLC) proliferation through nicotinic acetylcholine receptor (nAChR)-mediated signals. Activation of peroxisome proliferator-activated receptor gamma (PPARgamma) has been shown to inhibit NSCLC cell growth, but the exact mechanisms responsible for this effect remain incompletely defined. Herein, we show that nicotine induces NSCLC cell proliferation in part through alpha4 nAChR, prompting us to explore the effects of rosiglitazone, a synthetic PPARgamma ligand, on the expression of this receptor. Rosiglitazone inhibited the expression of alpha4 nAChR, but this effect was through a PPARgamma-independent pathway, because GW9662, an antagonist of PPARgamma, and the transfection of cells with PPARgamma small interfering RNA failed to abolish the response. The inhibitory effect of rosiglitazone on alpha4 nAChR expression was accompanied by phosphorylation of p38 mitogen-activated protein kinase and extracellular signal-regulated kinase 1/2 and down-regulation of Akt phosphorylation. These signals mediated the inhibitory effects of rosiglitazone on alpha4 nAChR expression because chemical inhibitors prevented the effect. Rosiglitazone was also found to stimulate p53, a tumor suppressor known to mediate some of the effects of nicotine. Interestingly, p53 up-regulation was needed for rosiglitazone-induced inhibition of alpha4 nAChR. Thus, rosiglitazone inhibits alpha4 nAChR expression in NSCLC cells through activation of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase, which triggers induction of p53. Finally, like others, we found that nicotine stimulated the expression of alpha4 nAChR. This process was also inhibited by rosiglitazone through similar pathways.