Oxidative Stress-Induced Unscheduled CDK1-Cyclin B1 Activity Impairs ER-Mitochondria-Mediated Bioenergetic Metabolism.

Targeting the activities of endoplasmic reticulum (ER)-mitochondrial-dependent metabolic reprogramming is considered one of the most promising strategies for cancer treatment. Here, we present biochemical subcellular fractionation, coimmunoprecipitation, gene manipulation, and pharmacologic evidence that induction of mitochondria-localized phospho (p)-cyclin dependent kinase 1 (CDK1) (Thr 161)-cyclin B1 complexes by apigenin in nasopharyngeal carcinoma (NPC) cells impairs the ER-mitochondrial bioenergetics and redox regulation of calcium (Ca++) homeostasis through suppressing the B cell lymphoma 2 (BCL-2)/BCL-2/B-cell lymphoma-extra large (BCL-xL)-modulated anti-apoptotic and metabolic functions. Using a specific inducer, inhibitor, or short hairpin RNA for acid sphingomyelinase (ASM) demonstrated that enhanced lipid raft-associated ASM activity confers alteration of the lipid composition of lipid raft membranes, which leads to perturbation of protein trafficking, and induces formation of p110α free p85α-unphosphorylated phosphatase and tensin homolog deleted from chromosome 10 complexes in the lipid raft membranes, causing disruption of phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt)-GTP-ras-related C3 botulinum toxin substrate 1 (Rac1)-mediated signaling, thus triggering the p-CDK1 (Thr 161))-cyclin B1-mediated BCL-2 (Thr 69/Ser 87)/BCL-xL (Ser 62) phosphorylation and accompanying impairment of ER-mitochondria-regulated bioenergetic, redox, and Ca++ homeostasis. Inhibition of apigenin-induced reactive oxygen species (ROS) generation by a ROS scavenger N-acetyl-L-cysteine blocked the lipid raft membrane localization and activation of ASM and formation of ceramide-enriched lipid raft membranes, returned PI3K-Akt-GTP-Rac1-modulated CDK1-cyclin B1 activity, and subsequently restored the BCL-2/BCL-xL-regulated ER-mitochondrial bioenergetic activity. Thus, this study reveals a novel molecular mechanism of the pro-apoptotic activity of ASM controlled by oxidative stress to modulate the ER-mitochondrial bioenergetic metabolism, as well as suggests the disruption of CDK1-cyclin B1-mediated BCL-2/BCL-xL oncogenic activity by triggering oxidative stress-ASM-induced PI3K-Akt-GTP-Rac1 inactivation as a therapeutic approach for NPC.

Antrodia cinnamomea, a Treasured Medicinal Mushroom, Induces Growth Arrest in Breast Cancer Cells, T47D Cells: New Mechanisms Emerge.

Reported cases of breast cancer have skyrocketed in the last decades with recent advances in examination techniques. Brest cancer has become the second leading cause of mortality among women worldwide, urging the scientific community to develop or find new drugs from natural sources with potent activity and a reasonable safety profile to tackle this ailment. Antrodia cinnamomea (AC) is a treasured medicinal fungus which has attracted attention due to its potent hepatoprotective and cytotoxic activities. We evaluated the antiproliferative activity of the ethanol extract of artificially cultured AC (EEAC) on breast cancer cells (T47D cells) in vivo and in vitro. Ethanol extract of artificially cultured AC inhibited T47D cells' proliferation mediated by cell cycle arrest at G1 phase as well induced autophagy. Immunoblotting assay confirmed that EEAC not only decreased the expression of the cell-cycle-related proteins but also increased the expression of transcription factor FOXO1, autophagic marker LC3 II, and p62. Ethanol extract of artificially cultured AC mediated endoplasmic reticulum stress by promoting the expression of IRE1 (inositol-requiring enzyme 1α), GRP78/Bip (glucose regulating protein 78), and CHOP (C/EBP homologous protein). Apart from previous studies, HDACs (histone deacetylases) activity was inhibited as demonstrated by a cell-free system, immunoblotting, and immunofluorescence assays following EEAC treatment. The in vivo studies demonstrated that EEAC decreased tumor volume and inhibited tumor growth without any significant side effects. High performance liquid chromatography profile demonstrated similar triterpenoids compared to the profile of wild AC ethanol extract. The multiple targets of EEAC on breast cancer cells suggested that this extract may be developed as a potential dietary supplement targeting this debilitating disease.

Correlation of genomic alterations between tumor tissue and circulating tumor DNA by next-generation sequencing.

PURPOSE: Analysis of circulating tumor DNA (ctDNA) offers an unbiased and noninvasive way to assess the genetic profiles of tumors. This study aimed to analyze mutations in ctDNA and their correlation with tissue mutations in patients with a variety of cancers. METHODS: We included 21 cancer patients treated with surgical resection for whom we collected paired tissue and plasma samples. Next-generation sequencing (NGS) of all exons was performed in a targeted human comprehensive cancer panel consisting of 275 genes. RESULTS: Six patients had at least one mutation that was concordant between tissue and ctDNA sequencing. Among all mutations (n = 35) detected by tissue and blood sequencing, 20% (n = 7) were concordant at the gene level. Tissue and ctDNA sequencing identified driver mutations in 66.67% and 47.62% of the tested samples, respectively. Tissue and ctDNA NGS detected actionable alterations in 57.14% and 33.33% of patients, respectively. When somatic alterations identified by each test were combined, the total proportion of patients with actionable mutations increased to 71.43%. Moreover, variants of unknown significance that were judged likely pathogenic had a higher percentage in ctDNA exclusively. Across six representative genes (PIK3CA, CTNNB1, AKT1, KRAS, TP53, and MET), the sensitivity and specificity of detection using mutations in tissue sample as a reference were 25 and 96.74%, respectively. CONCLUSIONS: This study indicates that tissue NGS and ctDNA NGS are complementary rather than exclusive approaches; these data support the idea that ctDNA is a promising tool to interrogate cancer genetics.

Genetic alterations in endometrial cancer by targeted next-generation sequencing.

Many genetic factors play important roles in the development of endometrial cancer. The aim of this study was to investigate genetic alterations in the Taiwanese population with endometrial cancer. DNA was extracted from 10 cases of fresh-frozen endometrial cancer tissue. The exomes of cancer-related genes were captured using the NimbleGen Comprehensive Cancer Panel (578 cancer-related genes) and sequenced using the Illumina Genomic Sequencing Platform. Our results revealed 120 variants in 99 genes, 21 of which were included in the Oncomine Cancer Research Panel used in the National Cancer Institute Match Trial. The 21 genes comprised 8 tumor suppressor candidates (ATM, MSH2, PIK3R1, PTCH1, PTEN, TET2, TP53, and TSC1) and 13 oncogene candidates (ALK, BCL9, CTNNB1, ERBB2, FGFR2, FLT3, HNF1A, KIT, MTOR, PDGFRA, PPP2R1A, PTPN11, and SF3B1). We identified a high frequency of mutations in PTEN (50%) and genes involved in the endometrial cancer-related molecular pathway, which involves the IL-7 signaling pathway (PIK3R1, n=1; AKT2, n=1; FOXO1, n=1). We report the mutational landscape of endometrial cancer in the Taiwanese population. We believe that this study will shed new light on fundamental aspects for understanding the molecular pathogenesis of endometrial cancer and may aid in the development of new targeted therapies.

The small molecule calactin induces DNA damage and apoptosis in human leukemia cells.

We purified calactin from the roots of the Chinese herb Asclepias curassavica L. and analyzed its biologic effects in human leukemia cells. Our results showed that calactin treatment caused DNA damage and resulted in apoptosis. Increased phosphorylation levels of Chk2 and H2AX were observed and were reversed by the DNA damage inhibitor caffeine in calactin-treated cells. In addition, calactin treatment showed that a decrease in the expression of cell cycle regulatory proteins Cyclin B1, Cdk1, and Cdc25C was consistent with a G2/M phase arrest. Furthermore, calactin induced extracellular signal-regulated kinase (ERK) phosphorylation, activation of caspase-3, caspase-8, and caspase-9, and PARP cleavage. Pretreatment with the ERK inhibitor PD98059 significantly blocked the loss of viability in calactin-treated cells. It is indicated that calactin-induced apoptosis may occur through an ERK signaling pathway. Our data suggest that calactin is a potential anticancer compound.

Impact of short-duration administration of N-acetylcysteine, probucol and ascorbic acid on contrast-induced cytotoxicity.

BACKGROUND: The best pharmaceutical prevention of contrast-medium-induced nephropathy for emergency procedures remains unknown. The aim of this study was to examine the impact of short-duration antioxidant pretreatment on contrast-medium-induced cytotoxicity. METHODS: Human embryonic kidney cells were treated with three different contrast media: ionic ioxitalamate, non-ionic low-osmolar iopromide, and iso-osmolar iodixanol. The doses and durations of pretreatment with antioxidants were 2 mM/L N-acetylcysteine for 15 minutes, 40 µM/L probucol for 30 minutes, and 30 µM/L ascorbic acid for 30 minutes. A supplementary dose of 2 mM/L N-acetylcysteine was administered 12 hours after contrast medium treatment. Cell viability was determined by tetrazolium MTT assay. RESULTS: All three contrast media caused significant reduction of cell viability at 24 hours (p<0.001). In the groups receiving iopromide or iodixanol, N-acetylcysteine pretreatment significantly improved cell viability compared with no N-acetylcysteine pretreatment (p<0.001). In the group receiving ioxitalamate, N-acetylcysteine pretreatment followed by a supplementary dose of N-acetylcysteine at 12 hours rather than N-acetylcysteine pretreatment alone significantly improved cell viability compared with no N-acetylcysteine pretreatment (p=0.038). Probucol or ascorbic acid pretreatment was unable to reduce cell death caused by the three contrast media. CONCLUSIONS: Short-duration pretreatment with N-acetylcysteine significantly reduced contrast-medium-induced cytotoxicity. These findings provide new insight into the prevention of contrast-medium-induced nephropathy in clinical emergency scenarios.

Cytotoxic effects produced by arecoline correlated to epigenetic regulation in human K-562 cells.

Epigenetic effects are considered heritable but may also be modified by environmental factors. Arecoline (ARC), a major component of areca nut alkaloids, is an important environmental risk factor for oral cancer and hepatocellular carcinomain Taiwan. The aim of this study was to determine the influence of ARC on the epigenome. The mRNA expression of histone methyltransferases, acetyltransferases, and demethylases were assessed in K-562 cells following exposure to ARC. Results demonstrated that ARC produced changes in the expressions of several genes catalyzing histone methylation (Mll, Setdb1, and Suv39h2), acetylation (Atf2), and demethylation (JMJD6). Since H3K9 methylation is involved in maintaining the stability of heterochromatin structures and inactivating euchromatic gene expressions, data suggest that the ARC-induced epigenetic changes play a role in the mechanisms underlying chemical-mediated cytotoxicity and genotoxicity.

Squamocin modulates histone H3 phosphorylation levels and induces G1 phase arrest and apoptosis in cancer cells.

BACKGROUND: Histone modifications in tumorigenesis are increasingly recognized as important epigenetic factors leading to cancer. Increased phosphorylation levels of histone H3 as a result of aurora B and pMSK1 overexpression were observed in various tumors. We selected aurora B and MSK1 as representatives for testing various compounds and drugs, and found that squamocin, a bis-tetrahydrofuran annonaceous acetogenin, exerted a potent effect on histone H3 phosphorylation. METHODS: GBM8401, Huh-7, and SW620 cells were incubated with 15, 30, and 60 µM squamocin for 24 h. The expressions of mRNA and proteins were analyzed by qRT-PCR and Western blotting, respectively. The cell viability was determined by an MTT assay. Cell cycle distribution and apoptotic cells were analyzed by flow cytometry. RESULTS: Our results showed that squamocin inhibited the proliferation of GBM8401, Huh-7, and SW620 cells, arrested the cell cycle at the G1 phase, and activated both intrinsic and extrinsic pathways to apoptosis. In addition, we demonstrated that squamocin had the ability to modulate the phosphorylation levels of H3S10 (H3S10p) and H3S28 (H3S28p) in association with the downregulation of aurora B and pMSK1 expressions. CONCLUSIONS: This study is the first to show that squamocin affects epigenetic alterations by modulating histone H3 phosphorylation at S10 and S28, providing a novel view of the antitumor mechanism of squamocin.

Glutathione S-transferase M1 gene polymorphisms are associated with cardiac iron deposition in patients with beta-thalassemia major.

Patients with beta-thalassemia (thal) major are subject to peroxidative tissue injury by iron overload. Glutathione S-transferases work as antioxidants, and their activity is determined genetically. In this study, we used multiplex polymerase chain reaction (m-PCR) to analyze polymorphisms of two endogenous antioxidant agents, glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1), and to determine their roles in 41 patients with beta-thal major. Our results showed that the GSTM1 and GSTT1 null genotypes were not associated with any incidence of endocrine dysfunction (including diabetes mellitus, hypogonadism, hypothyroidism, and growth hormone deficiency), liver function, or impaired left ventricular ejection fraction (LVEF). The GSTM1 null genotype, but not the GSTT1 null genotype, was associated with a decreased signal intensity ratio on cardiac magnetic resonance imaging (MRI). Our results suggest that genetic variations of the GSTM1 enzyme are associated with cardiac iron deposition in patients with beta-thal major.

Disturbance of circadian gene expression in endometrial cancer: detection by real-time quantitative RT-PCR.

Circadian genes control the daily changes of the circadian rhythms in a variety of physiological processes, which in turn regulate many functions in the human body. Disruption of circadian rhythms can have a profound influence on our well-being. We established a set of PCR primers and fluorescent probes to analyze the mRNA levels of nine different circadian genes, and used immunohistochemical methods to study four important circadian proteins in 35 endometrial cancers and their paired non-cancerous tissues. Of these, 13 cases showed reduced expression in all nine circadian genes in the cancerous tissues relative to the paired non-cancerous tissues; the remaining cases showed similar reduced expression in 4-8 of the genes analyzed. Conversely, 3 non-cancerous tissues showed reduced expression in all nine circadian genes in comparison with their respective adjacent cancerous tissues, whereas 6 other non-cancerous tissues showed reduced expression in 6-8 of the circadian genes. These results were also confirmed by immunohistochemical study. Expression of the circadian genes is perturbed in endometrial cancer. Based on these results, we suggest that different circadian rhythms occur in endometrial cancer and non-cancerous tissues. Our results may provide the molecular basis for chronotherapy of endometrial cancer.

Deregulated expression of the PER1, PER2 and PER3 genes in breast cancers.

Disruption of circadian rhythm may be a risk factor in the development of breast cancer, but molecular changes in circadian rhythm controlled genes in breast cancer cells are still unexplored. We used immunohistochemical staining, methylation specific PCR and direct sequencing methods to analyze molecular changes in three most important genes, namely PER1, PER2 and PER3, in circadian rhythm in 55 cases of breast cancer of Taiwanese women. Our results reveal disturbances in the expression of the three period (PER) genes in most (>95%) of the breast cancerous cells in comparison with the nearby non-cancerous cells. The PER gene deregulation is not caused by genetic mutations but most probably by methylation of the PER1 or PER2 promoter. Methylation of the PER gene promoters has a strong correlation with c-erbB2 expression (P = 0.017). Since the circadian clock controls expression of cell-cycle related genes, we suggest that disturbances in PER gene expression may result in disruption of the control of the normal circadian clock, thus benefiting the survival of cancer cells and promoting carcinogenesis. Differential expression of circadian genes in non-cancerous and cancerous cells may provide a molecular basis for chronotherapy of breast cancer.