Apoptosis-Inducing Factor and Colon Cancer

Identification of key genes and biological processes contributing to colitis associated dysplasia in ulcerative colitis

Background

Ulcerative colitis-associated colorectal cancer (UC-CRC) is a life-threatening complication of ulcerative colitis (UC). The mechanisms underlying UC-CRC remain to be elucidated. The purpose of this study was to explore the key genes and biological processes contributing to colitis-associated dysplasia (CAD) or carcinogenesis in UC via database mining, thus offering opportunities for early prediction and intervention of UC-CRC.

Methods

Microarray datasets (GSE47908 and GSE87466) were downloaded from Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) between groups of GSE47908 were identified using the “limma” R package. Weighted gene co-expression network analysis (WGCNA) based on DEGs between the CAD and control groups was conducted subsequently. Functional enrichment analysis was performed, and hub genes of selected modules were identified using the “clusterProfiler” R package. Single-gene gene set enrichment analysis (GSEA) was conducted to predict significant biological processes and pathways associated with the specified gene.

Results

Six functional modules were identified based on 4929 DEGs. Green and blue modules were selected because of their consistent correlation with UC and CAD, and the highest correlation coefficient with the progress of UC-associated carcinogenesis. Functional enrichment analysis revealed that genes of these two modules were significantly enriched in biological processes, including mitochondrial dysfunction, cell-cell junction, and immune responses. However, GSEA based on differential expression analysis between sporadic colorectal cancer (CRC) and normal controls from The Cancer Genome Atlas (TCGA) indicated that mitochondrial dysfunction may not be the major carcinogenic mechanism underlying sporadic CRC. Thirteen hub genes (SLC25A3, ACO2, AIFM1, ATP5A1, DLD, TFE3, UQCRC1, ADIPOR2, SLC35D1, TOR1AIP1, PRR5L, ATOX1, and DTX3) were identified. Their expression trends were validated in UC patients of GSE87466, and their potential carcinogenic effects in UC were supported by their known functions and other relevant studies reported in the literature. Single-gene GSEA indicated that biological processes and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to angiogenesis and immune response were positively correlated with the upregulation of TFE3, whereas those related to mitochondrial function and energy metabolism were negatively correlated with the upregulation of TFE3.

Conclusions

Using WGCNA, this study found two gene modules that were significantly correlated with CAD, of which 13 hub genes were identified as the potential key genes. The critical biological processes in which the genes of these two modules were significantly enriched include mitochondrial dysfunction, cell-cell junction, and immune responses. TFE3, a transcription factor related to mitochondrial function and cancers, may play a central role in UC-associated carcinogenesis.

The apoptosis-inducing factor family: Moonlighting proteins in the crosstalk between mitochondria and nuclei

In Homo sapiens, the apoptosis-inducing factor (AIF) family is represented by three different proteins, known as AIF, AMID and AIFL, that have in common the mitochondrial localisation in healthy cells, the presence of FAD- and NADH-dependent domains involved in an -albeit yet not well understood- oxidoreductase function and their capability to induce programmed cell death. AIF is the best characterised family member, while the information about AMID and AIFL is much scarcer. Nonetheless, available data support different roles as well as mechanisms of action of their particular apoptogenic and redox domains regarding both pro-apoptotic and anti-apoptotic activities. Moreover, diverse cellular functions, to date far from fully clarified, are envisaged for the transcripts corresponding to these three proteins. Here, we review the so far available knowledge on the moonlighting human AIF family from their molecular properties to their relevance in health and disease, through the evaluation of their potential cell death and redox functions in their different subcellular locations. This picture emerging from the current knowledge of the AIF family envisages its contribution to regulate signalling and transcription machineries in the crosstalk among mitochondria, the cytoplasm and the nucleus.

Apoptosis-inducing factor plays a role in the pathogenesis of hepatic and renal injury during cholestasis

Cholestasis is a clinical complication with different etiologies. The liver is the primary organ influenced in cholestasis. Renal injury is also a severe clinical complication in cholestatic/cirrhotic patients. Several studies mentioned the importance of oxidative stress and mitochondrial impairment as two mechanistically interrelated events in cholestasis-induced organ injury. Apoptosis-inducing factor (AIF) is a flavoprotein located in the inner mitochondrial membrane. This molecule is involved in a distinct pathway of cell death. The current study aimed to evaluate the role of AIF in the pathophysiology of cholestasis-associated hepatic and renal injury. Bile duct ligation (BDL) was used as an animal model of cholestasis. Serum, urine, and tissue samples were collected at scheduled time intervals (3, 7, 14, and 28 days after BDL surgery). Tissues' AIF mRNA levels, as well as serum, urine, and tissue activity of AIF, were measured. Moreover, markers of DNA fragmentation and apoptosis were assessed in the liver and kidney of cholestatic animals. A significant increase in liver and kidney AIF mRNA levels, in addition to increased AIF activity in the liver, kidney, serum, and urine, was detected in BDL rats. DNA fragmentation and apoptosis were raised in the liver and kidney of cholestatic animals, especially at the early stage of the disease. The apoptotic mode of cell death in the liver and kidney was connected to a higher AIF level. These data mention the importance of AIF in the pathogenesis of cholestasis-induced organ injury, especially at the early stage of this disease. Mitochondrial release of apoptosis-inducing factor (AIF) seems to play a pathogenic role in cholestasis-associated hepatic and renal injury. AIF release is directly connected to oxidative stress and mitochondrial impairment in cholestatic animals.

Epoxycytochalasin H: An Endophytic Phomopsis Compound Induces Apoptosis in A2780 Cells Through Mitochondrial Damage and Endoplasmic Reticulum Stress

Background

Natural compounds extracted from plants have been reported to have antitumor activity. A fungal metabolite from Phomopsis, identified as epoxycytochalasin H and isolated from the flowering plant Polygonatum sibiricum, was found to have significant antitumor activity. In this study, we report the antitumor effects and mechanism of action of epoxycytochalasin H in the ovarian cancer cell line A2780. Our data suggest that epoxycytochalasin H markedly reduces cell proliferation and induces apoptosis in ovarian cancer cells.

Materials and Methods

The viability, apoptosis and colony formation of A2780 cells, treated with epoxycytochalasin H, were detected by MTT assay, nuclear staining, flow cytometry, and clone formation assay. MitoROS and mitochondrial membrane potentials were detected by MitoSOX staining and flow cytometry. The expression of proteins associated with apoptosis, autophagy, and endoplasmic reticulum stress, in A2780 cells treated with epoxycytochalasin H, was detected by Western blot. Effects of mitophagy were detected in Parkin-overexpressing 293T cells.

Results

Our data suggested that epoxycytochalasin H could strongly reduce cell proliferation and induce apoptosis in ovarian cancer cell line A2780. Epoxycytochalasin H induced apoptosis through mitochondrial injury, mitophagy, and endoplasmic reticulum stress. Specifically, epoxycytochalasin H increased ROS level in cells, and in mitochondria, it decreased mitochondrial membrane potential, caused mitochondrial injury, activated macroautophagy and mitophagy, and subsequently induced apoptosis via the mitochondrial pathway. Additionally, it was discovered that epoxycytochalasin H could induce apoptosis more significantly in 293T cells overexpressing Parkin than in the parental cells. Thus, the mitophagy activated by epoxycytochalasin H could promote apoptosis. In addition, epoxycytochalasin H mediated endoplasmic reticulum stress-related apoptosis.

Conclusion

Epoxycytochalasin H could promote apoptosis of human ovarian cancer A2780 cells by activating mitochondrial and endoplasmic reticulum stress-related apoptotic pathways.

Is visceral obesity associated with colorectal cancer? The first volumetric study using all CT slices

PURPOSE

We aimed to examine the possible relationship between abdominal adiposity parameters and the presence of colorectal cancer (CRC) and between these adiposity parameters and various histopathologic findings of the tumor.

METHODS

A total of 60 control subjects and 111 CRC patients, 63 with early-stage and 48 with advanced-stage disease, were enrolled. Medical data and abdominopelvic computed tomography (CT) examinations of each study group were retrospectively reviewed. Abdominal adiposity parameters, including visceral adipose tissue (VAT) volume, subcutaneous adipose tissue (SAT) volume, and total adipose tissue (TAT) volume, were calculated on all slices of the CT examinations with specialized software, and results for each study group were compared. Adiposity parameters were also compared with tumor histopathologic findings.

RESULTS

We found lower VAT and higher SAT volumes in advanced-stage CRC patients, compared with the early-stage group. However, this relationship was not statistically significant (P = 0.721 for VAT and P = 0.432 for SAT volumes). We detected significantly lower VAT and SAT volumes in the early-stage CRC group compared with the control group (P = 0.014 for both). There was no significant relationship between TAT volumes and the study groups (P = 0.06). No statistically significant relationship was detected between adipose tissue parameters and histopathologic features of the CRC group (P > 0.05).

CONCLUSION

We found statistically significant lower VAT and SAT volumes in patients with early-stage CRC compared with the control group. Volumetric adipose tissue measurements may be more accurate than area measurements and can easily be performed on abdominopelvic CT examination, which is the routine imaging modality for CRC patients.

Downregulation of AIF-2 Inhibits Proliferation, Migration, and Invasion of Human Glioma Cells via Mitochondrial Dysfunction

Glioma remains the leading cause of brain tumor-related death worldwide. Apoptosis inducing factor (AIF) is a family of mitochondrial oxidoreductases that play important roles in mitochondrial metabolism and redox control. AIF-1 has been demonstrated to exert cell-killing effect via apoptosis in cancer cells, whereas the role of AIF-2 in cancer cells has not been determined. This study aimed to investigate the role of AIF-2 in human glioma cells. We found that AIF-2 was upregulated in human glioma tissues and cell lines, especially in U251 cells. Downregulation of AIF-2 using specific siRNA (Si-AIF-2) significantly reduced cell proliferation, induced G1 cell cycle arrest and differently regulated the expression of cell cycle regulator proteins in U251 cells. In addition, the results of Matrigel invasion assay and live-cell tracking assay showed that knockdown of AIF-2 inhibited cell invasion and migration. The results of immunocytochemistry indicated that knockdown of AIF-2 significantly attenuated the nuclear translocation of AIF-1, which was confirmed by western blot analysis. Furthermore, downregulation of AIF-2 resulted in mitochondrial dysfunction in U251 cells, as evidenced by reduced mitochondrial membrane potential (MMP), mitochondrial complex I activity, and mitochondrial Ca2+ buffering capacity. In conclusion, we found that AIF-2 plays a key role in promoting cell proliferation, invasion, and migration via regulating AIF-1-related mitochondrial cascades. Downregulation of the candidate oncogene AIF-2 might constitute a strategy to kill human glioma cells.

Combinatorial Electrophoresis and Mass Spectrometry-Based Proteomics in Breast Milk for Breast Cancer Biomarker Discovery

Innovations in approaches for early detection and individual risk assessment of different cancers, including breast cancer (BC), are needed to reduce cancer morbidity and associated mortality. The assessment of potential cancer biomarkers in accessible bodily fluids provides a novel approach to identify the risk and/or onset of cancer. Biomarkers are biomolecules, such as proteins, that are indicative of an abnormality or a disease. Human milk is vastly underutilized biospecimen that offers the opportunity to investigate potential protein BC-biomarkers in young, reproductively active women. As a first step, we have examined the entire protein pattern in human milk samples from breastfeeding mothers with cancer, who were diagnosed either before or after milk donation, and from women without cancer, using mass spectrometry (MS)-based proteomics.

Tohid SF. Dicranopteris linearis extract inhibits the proliferation of human breast cancer cell line (MDA-MB-231) via induction of S-phase arrest and apoptosis

CONTEXT

Dicranopteris linearis (Burm.f.) Underw. (Gleicheniaceae) has been scientifically proven to exert various pharmacological activities. Nevertheless, its anti-proliferative potential has not been extensively investigated.

OBJECTIVE

To investigate the anti-proliferative potential of D. linearis leaves and determine possible mechanistic pathways.

MATERIALS AND METHODS

MTT assay was used to determine the cytotoxic effects of D. linearis methanol (MEDL) and petroleum ether (PEEDL) extracts at concentrations of 100, 50, 25, 12.5, 6.25 and 3.125 µg/mL against a panel of cancer cell lines (breast [MCF-7 and MDA-MB-231], cervical [HeLa], colon [HT-29], hepatocellular [HepG2] and lung [A549]), as compared to negative (untreated) and positive [5-fluorouracil (5-FU)-treated] control groups. Mouse fibroblast cells (3T3) were used as normal cells. The mode of cell death was examined using morphological analysis via acridine orange (AO) and propidium iodide (PI) double staining. Cell cycle arrest was determined using flow cytometer, followed by annexin V-PI apoptosis detection kit.

RESULTS

MEDL demonstrated the most significant growth inhibition against MDA-MB-231 cells (IC₅₀ 22.4 µg/mL). PEEDL showed no cytotoxic effect. Induction of apoptosis by MEDL was evidenced via morphological analysis and acridine orange propidium iodide staining. MEDL could induce S phase cell cycle arrest after 72 h of incubation. Early apoptosis induction in MDA-MB-231 cells was confirmed by annexin V-FITC and PI staining. Significant increase in apoptotic cells were detected after 24 h of treatment with 15.07% cells underwent apoptosis, and the amount escalated to 18.24% with prolonged 48 h incubation.

CONCLUSIONS

MEDL has potential as a potent cytotoxic agent against MDA-MB-231 adenocarcinoma.

Chemopreventive Potential of Cereal Polyphenols

It has been identified that diet is one of the major contributing factors associated with the development of cancer and other chronic pathologies. In the recent years, supplementing regular diet with food and/or its components that contain chemopreventive properties has been considered an effective approach in reducing the incidence of cancer and other lifestyle associated diseases. This systematic review provides an exhaustive summary of the chemopreventive properties exhibited by everyday dietary ingredients such as rice, barley, oats, and sorghum. The studies both in vitro and in vivo reviewed have highlighted the potential role of their polyphenolic content as chemopreventive agents. Polyphenolic compounds including anthocyanins, tricin, protocatechualdehyde, avenanthramide, and 3-deoxyanthocyanins found in rice, barley, oats, and sorghum, respectively, were identified as compounds with potent bioactivity. Studies demonstrated that cereal polyphenols are likely to have chemopreventive activities, particularly those found in pigmented varieties. In conclusion, findings suggest that the consumption of pigmented cereals could potentially have an important role as a natural complementary cancer preventive therapeutic. However, further studies to develop a complete understanding of the mechanisms by which phenolic compounds inhibit cancerous cell proliferation are warranted.

AIF promotes a JNK1-mediated cadherin switch independently of respiratory chain stabilization

Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein occasionally involved in cell death that primarily regulates mitochondrial energy metabolism under normal cellular conditions. AIF catalyzes the oxidation of NADH in vitro, yet the significance of this redox activity in cells remains unclear. Here, we show that through its enzymatic activity AIF is a critical factor for oxidative stress-induced activation of the mitogen-activated protein kinases JNK1 (c-Jun N-terminal kinase), p38, and ERK (extracellular signal-regulated kinase). AIF-dependent JNK1 signaling culminates in the cadherin switch, and genetic reversal of this switch leads to apoptosis when AIF is suppressed. Notably, this widespread ability of AIF to promote JNK signaling can be uncoupled from its more limited role in respiratory chain stabilization. Thus, AIF is a transmitter of extra-mitochondrial signaling cues with important implications for human development and disease.

Anti-tumor properties of anthocyanins from Lonicera caerulea 'Beilei' fruit on human hepatocellular carcinoma: In vitro and in vivo study

In this study, the anthocyanin from Lonicera caerulea 'Beilei' fruit (ABL) was extracted and purified. The purified component (ABL-2) was then evaluated for its anti-tumor properties on human hepatoma cells (SMMC-7721) in vitro and the murine hepatoma cells (H22) in vivo. In vitro, ABL-2 not only significantly inhibited the growth of SMMC-7721 cells, but also remarkably blocked the cells' cycle in G2/M phase, inducing DNA damage and eventually leading to apoptosis. In vivo, ABL also killed tumor cells, inhibited tumor growth, and improved the survival status of H22 tumor-bearing mice. These effects were associated with an increase in the activities of antioxidase and a decrease in the level of lipid peroxidation, as evidenced by changes in SOD, GSH-Px, GSH, and MDA levels. In addition, ABL-2 also regulated the levels of immune cytokines including IL-2, IFN-γ, and TNF-α. These results revealed that ABL-2 exerts an effective anti-tumor effect by dynamically adjusting the REDOX balance and improving the immunoregulatory activity of H22 tumor-bearing mice. High performance liquid chromatography (HPLC) analysis revealed that cyanidin-3,5-diglucoside (8.16 mg/g), cyanidin-3-glucoside (387.60 mg/g), cyanidin-3-rutinoside (23.62 mg/g), and peonidin-3-glucoside (22.20 mg/g) were the main components in ABL-2, which may contribute to its anti-tumor activity.

Comparative two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) of human milk to identify dysregulated proteins in breast cancer

Breast cancer (BC) remains a major cause of mortality, and early detection is considered important for reducing BC-associated deaths. Early detection of BC is challenging in young women, due to the limitations of mammography on the dense breast tissue of young women. We recently reported results of a pilot proteomics study, using one-dimensional polyacrylamide gel electrophoresis (1D-PAGE) and mass spectrometry (MS) to investigate differences in milk proteins from women with and without BC. Here, we applied two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and MS to compare the protein pattern in milk from the breasts of a single woman who was diagnosed with BC in one breast 24 months after donating her milk. Statistically different gel spots were picked for protein digestion followed by nanoliquid chromatography tandem MS (nanoLC-MS/MS) analysis. The upregulated proteins in BC versus control are alpha-amylase, gelsolin isoform a precursor, alpha-2-glycoprotein 1 zinc isoform CRA_b partial, apoptosis-inducing factor 2 and vitronectin. Several proteins were downregulated in the milk of the breast later diagnosed with cancer as compared to the milk from the healthy breast, including different isoforms of albumin, cholesterol esterase, different isoforms of lactoferrin, different proteins from the casein family and different isoforms of lysozyme. Results warrant further studies to determine the usefulness of these milk proteins for assessing risk and detecting occult disease. MS data is available via ProteomeXchange with identifier PXD009860.

In vitro Cytotoxicity and Apoptotic Assay in HT-29 Cell Line Using Ficus hispida Linn: Leaves Extract

Background:

Ficus hispida Linn. (Family Moraceae), well-known beneficial medicinal shrub, has been traditionally used for the treatment of various diseases such as leukoderma.

Objective:

The aim of the present study is to investigate the efficacy of F. hispida ethanolic leaves extract for antiproliferative, apoptotic, cell cycle blockade, and wound healing.

Materials and Methods:

F. hispida leaves extract was treated with colorectal adenocarcinoma cancer cell line HT29 for 24 h with control. The cells were treated at varying concentration ranges of 15, 31, 62, 125, and 250 μg/ml each The cytotoxicity effect of leaves extract was studied by 3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyltetrazolium bromide assay and their anticancer activity was further evaluated using cell cycle analysis and wound scratch assay.

Results:

The end antiproliferative result showed that HT-29 cell viability decreases in a concentration-dependent manner and the growth inhibitory effect (IC50) values are obtained at a concentration of 125 μg. The increase in number of apoptotic cell was observed after treating HT-29 cells with the sample in double-staining methods. G0/G1 phase of the cell cycle was significantly blocked by the test sample followed by the G2/M phase in a negligible manner. In vitro cell wound closure or contracture was not significant when compared the sample against control group.

Conclusion:

F. hispida Linn. ethanolic leaves extract had shown to possess excellent cytotoxic effect through inducing apoptosis, especially causing cell cycle arrest at the G0/G1 phase.

SUMMARY

The experiment tries to evaluate the effectiveness of F. hispida leaves extract as an antiproliferative, apoptotic, cell cycle inhibitor and wound healing agent. Results showed that F. hispida Linn extract own cytotoxic property by inducing apoptosis through cell cycle arrest.

Abbreviations used: HT 29: Human adenocarcinoma colorectal cell line; PBS: Phosphate Buffered Saline; FBS: Fetal Bovine Serum; DMEM: Dulbecco's Modified Eagles Medium; MTT: 3 [4, 5 dimethylthiazol 2 yl] 2, 5 diphenyltetrazolium bromide; NCCS: National Centre for Cell Sciences; DMSO: DiMethyl SulfOxide; PI: Propidium Iodide; AO: Acridine Orange;EB: Ethidium Bromide; IC: Inhibitory Concentration.

miR-19b-3p promotes colon cancer proliferation and oxaliplatin-based chemoresistance by targeting SMAD4: validation by bioinformatics and experimental analyses

Background

As a disease with extremely complex molecular mechanisms, many deregulated miRNAs have been identified in colon cancer. Few studies have been performed by using Ingenuity Pathways Analysis (IPA) to predict miRNAs specifically expressed in colon cancer.

Methods

A characteristic microRNA-target network of colon cancer was explored using IPA. Then the clinical significance of miR-19b-3p was evaluated in 211 colon cancer patients. The roles of miR-19b-3p and its candidate target gene, SMAD4, in colon cancer progression were examined both in vitro and in vivo.

Results

Bioinformatics analysis showed that 15 microRNAs screened by IPA were significantly correlated with malignant biological behaviors of colon cancer. miR-19b-3p was the most significantly upregulated candidate based on the validation experiment using 211 colon cancer samples. High expression of miR-19b-3p was significantly associated with high N stage (P < 0.001), high AJCC stage (P < 0.001), poor histologic grade (P = 0.032), frequent venous and lymphatic invasion (P = 0.027), and liver metastasis (P < 0.001). Survival analysis revealed that miR-19b-3p was an independent prognostic factor associated with colon cancer patient’s overall survival (OS) and disease-free survival (DFS). miR-19b-3p promoted proliferation and chemoresistance of colon cancer cells, but had no effect on invasion in vitro, along with tumorigenesis in vivo. In addition, we confirmed that miR-19b-3p mediates resistance to oxaliplatin-based chemotherapy via SMAD4.

Conclusions

Our findings demonstrate the role of miR-19b-3p-SMAD4 axis in colon cancer progression, which may become a potential therapeutic target against chemotherapy resistance.

Electronic supplementary material

The online version of this article (10.1186/s13046-017-0602-5) contains supplementary material, which is available to authorized users.

Schiff base derived from thiosemicarbazone and anthracene showed high potential in overcoming multidrug resistance in vitro with low drug resistance index

Multidrug resistance (MDR) is a huge obstacle in cancer chemotherapeutics. Overcoming MDR is a great challenge for anticancer drug discovery. Here, DNA binding and cytotoxicity of Schiff base L1 and L2 were explored to assess their efficiency in fighting cancer and overcoming the MDR. L1 and L2 could treat extremely chemoresistant MCF-7/ADR cell as drug-sensitive cell, with drug resistance index (DRI) <2.13, showing high potential in overcoming the MDR. The apoptotic ratio induced by L1 and L2 was low for both MCF-7 and MCF-7/ADR cells. L1 and L2 induced an impairment of cell cycle progression of MCF-7 and MCF-7/ADR cell lines and suppressed cell growth by perturbing progress through the G0/G1 phase, with L2 causing more profound effect, which might account for lower drug resistance after L2 treatment. The molecular docking revealed weak interaction between L1/L2 and P-glycoprotein (P-gp), the most important drug efflux pump and intracellular Rhodamine 123 accumulation indicated that the activity of P-gp was not inhibited by L1 and L2. Combined with the cellular uptake results, it implied that L1 and L2 could bypass P-gp efflux to exert anticancer activity.

Preliminary evaluation for Bit1 as a potential biomarker for squamous cell carcinoma and adenocarcinoma of esophagus

Mounting evidence has demonstrated that Bit1 has been investigated as an etiological factor for certain cancers, including esophageal squamous cell carcinoma reported in our previous study, but data regarding possible roles of Bit1 in esophageal squamous cell carcinoma and esophageal adenocarcinoma remain to be elucidated. The purpose of this study was to examine whether Bit1 can be a novel diagnostic marker for the patients with esophageal squamous cell carcinoma and esophageal adenocarcinoma. The results revealed that Bit1 level in esophageal squamous cell carcinoma was significantly higher than that in esophageal adenocarcinoma tissues ( p < 0.05); notably, Bit1 level in esophageal adenocarcinoma tissues was lower than that in paired normal tissues but no difference was found ( p > 0.05). Bit1 expression patterns were completely in accordance with matrix metalloproteinase 2 and Bcl-2 in esophageal squamous cell carcinoma and esophageal adenocarcinoma. In addition, Bit1, Bcl-2, and matrix metalloproteinase 2 expression patterns in different differentiated esophageal squamous cell carcinoma were higher than those in corresponding normal esophageal tissues. Bit1 expression in poorly differentiated esophageal squamous cell carcinoma was significantly higher than that in normal esophageal tissues ( p < 0.05) but not in moderately and well-differentiated esophageal squamous cell carcinoma. Matrix metalloproteinase 2 expression patterns in poorly and moderately differentiated esophageal squamous cell carcinoma were significantly higher than those in corresponding normal esophageal tissues ( p < 0.01) but not in well-differentiated esophageal squamous cell carcinoma tissue ( p > 0.05). Bcl-2 expression patterns in various differentiated esophageal squamous cell carcinoma were higher than those in corresponding normal esophageal tissues with no statistical differences ( p > 0.05). Importantly, Bit1 expression was positively correlated with both matrix metalloproteinase 2 and Bcl-2 expression in esophageal squamous cell carcinoma and esophageal adenocarcinoma tissues ( p < 0.05). Collectively, these preliminary data support further investigation of Bit1 as an important diagnostic factor for esophageal squamous cell carcinoma and esophageal adenocarcinoma.

Perfluorooctanoic acid induces oxidative damage and mitochondrial dysfunction in pancreatic β-cells

Several environmental contaminants have been linked to the development of diabetes and increased diabetes‑associated mortality. Perfluorooctanoic acid (PFOA) is a widely used perfluoroalkane found in surfactants and lubricants, and in processing aids used in the production of polymers. Furthermore, PFOA has been detected in humans, wildlife and the environment. The present study investigated the toxic effects of PFOA on rat pancreatic β‑cell‑derived RIN‑m5F cells. Cell viability, apoptosis, reactive oxygen and nitrogen species, cytokine release and mitochondrial parameters, including membrane potential collapse, reduced adenosine triphosphate levels, cardiolipin peroxidation and cytochrome c release were assessed. PFOA significantly decreased RIN‑m5F cell viability and increased apoptosis. Exposure to PFOA increased the formation of reactive oxygen species, mitochondrial superoxide, nitric oxide and proinflammatory cytokines. Furthermore, PFOA induced mitochondrial membrane potential collapse and reduced adenosine triphosphate levels, cardiolipin peroxidation and cytochrome c release. These results indicate that PFOA is associated with the induction of apoptosis in RIN-m5F cells, and induces cytotoxicity via increased oxidative stress and mitochondrial dysfunction.

Apoptotic pathways and stemness in the colorectal epithelium and lamina propria mucosae during the human embryogenesis and carcinogenesis

AIM

Programmed cell death is essential both during normal organ development and carcinogenesis. In this study we immunohistochemically analyzed different pathways of cell death in 11 human conceptuses 5th-10th-weeks old, 10 low and high grade colorectal carcinomas (CRC), and 10 normal colon samples by using markers for apoptosis (caspase-3, AIF, TUNEL), proliferation (Ki-67) and stemness (Oct-4).

RESULTS

Between the 5th and 10th week of development, caspase-3 and AIF showed moderate-to-strong expression in the developing gut wall. During development, number of caspase-3-reactive cells decreased, while AIF increased. While healthy colorectal control and low grade CRC showed moderate expression of caspase-3 and AIF, in high grade CRC their expression was strong. Tumor tissues displayed significantly higher number of positive cells than controls. Occasionally, co-expressing of both markers characterized dying cells. In developing colon, Oct-4 and Ki-67 showed moderate-to-strong expression, while some cells co-expressed both markers. Their number decreased in the epithelium and increased in the connective tissue in later development. Healthy colorectal control displayed moderate Ki-67 and mild Oct-4 reactivity. While in low-grade CRC expression Oct-4 and Ki-67 was moderate, in high-grade CRC their expression was strong. Although Oct-4 and TUNEL occasionally co-expressed in all samples, both grades of CRC contained cells that were Oct-4 positive only.

CONCLUSION

Our study revealed two different parallel pathways of cell death, with characteristic increase of AIF-mediated apoptosis when compared to caspase-3, and presence of stemness cells both during colon development and carcinogenesis. These finding might be considered as important diagnostic, survival and CRC therapy predictors.

Basal metabolic state governs AIF-dependent growth support in pancreatic cancer cells

Background

Apoptosis-inducing factor (AIF), named for its involvement in cell death pathways, is a mitochondrial protein that regulates metabolic homeostasis. In addition to supporting the survival of healthy cells, AIF also plays a contributory role to the development of cancer through its enzymatic activity, and we have previously shown that AIF preferentially supports advanced-stage prostate cancer cells. Here we further evaluated the role of AIF in tumorigenesis by exploring its function in pancreatic cancer, a disease setting that most often presents at an advanced stage by the time of diagnosis.

Methods

A bioinformatics approach was first employed to investigate AIF mRNA transcript levels in pancreatic tumor specimens vs. normal tissues. AIF-deficient pancreatic cancer cell lines were then established via lentiviral infection. Immunoblot analysis was used to determine relative protein quantities within cells. Cell viability was measured by flow cytometry; in vitro and Matrigel™ growth/survival using Coulter™ counting and phase contrast microscopy; and glucose consumption in the absence and presence of Matrigel™ using spectrophotometric methods.

Results

Archival gene expression data revealed a modest elevation of AIF transcript levels in subsets of pancreatic tumor specimens, suggesting a possible role in disease progression. AIF expression was then suppressed in a panel of five pancreatic cancer cell lines that display diverse metabolic phenotypes. AIF ablation selectively crippled the growth of cells in vitro in a manner that directly correlated with the loss of mitochondrial respiratory chain subunits and altered glucose metabolism, and these effects were exacerbated in the presence of Matrigel™ substrate. This suggests a critical metabolic role for AIF to pancreatic tumorigenesis, while the spectrum of sensitivities to AIF ablation depends on basal cellular metabolic phenotypes.

Conclusions

Altogether these data indicate that AIF supports the growth and survival of metabolically defined pancreatic cancer cells and that this metabolic function may derive from a novel mechanism so far undocumented in other cancer types.

Quince peel polyphenolic extract blocks human colon adenocarcinoma LS174 cell growth and potentiates 5-fluorouracil efficacy

Background

Development of alternative cancer-specific drugs would be of paramount importance to overcome toxicity toward normal tissues and tumor resistance. Here, we investigated the potential anti-tumoral effect of peel (Peph) and pulp polyphenolic extracts from the Tunisian quince Cydonia oblonga Miller on both no-tumorigenic cells NIH 3T3 Fibroblasts and HEK 293 cells and human colon adenocarcinoma LS174 cells.

Methods

Cell proliferation and cytotoxicity were measured with MTT and LDH assays respectively. Cell cycle distribution and the apoptosis levels were assessed by flow cytometry. Intracellular reactive oxygen species (ROS) levels were determined using the fluorescent probe CM-H2DCFDA. Western blot was used to further characterize cell death and analyze the signaling pathways affected by Peph treatment. The expression level of VEGF-A was evaluated by real time quantitative PCR and further verified by quantifying the secreted cytokines by enzyme-linked immunosorbent assay.

Results

We found that Peph extract displayed the highest anti-proliferative effect specifically on LS174 cells. However, each Peph phenolic compound alone did not exhibit any anti-proliferative activity, suggesting a synergistic effect of phenolic molecules. Such effect was associated with a cell cycle arrest in the G1/S phase, a caspase-independent apoptosis and an increase of the ROS production. Peph extract inhibited the pro-survival signaling pathway NFκB and suppressed the expression of various cellular markers known to be involved in cell cycling (cyclin D1) and angiogenesis (Vascular Endothelial Growth Factor, VEGF). Interestingly, the combination Peph extract and 5-FU exerted synergistic inhibitory effect on cell viability.

Conclusion

These data propose the quince Peph extract as a promising cost effective non toxic drug to employ alone or in combination with conventional anti-colorectal cancer. Moreover, quince rich regimen may prevent the development and the progress of colon cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-016-0276-7) contains supplementary material, which is available to authorized users.

Lebein, a snake venom disintegrin, suppresses human colon cancer cells proliferation and tumor-induced angiogenesis through cell cycle arrest, apoptosis induction and inhibition of VEGF expression

Lebein, is an heterodimeric disintegrin isolated from Macrovipera lebetina snake venom that was previously characterized as an inhibitor of ADP-induced platelet aggregation. In this study, we investigated the effect of Lebein on the p53-dependent growth of human colon adenocarcinoma cell lines. We found that Lebein significantly inhibited LS174 (p53wt), HCT116 (p53wt), and HT29 (p53mut) colon cancer cell viability by inducing cell cycle arrest through the modulation of expression levels of the tumor suppression factor p53, cell cycle regulating proteins cyclin D1, CDK2, CDK4, retinoblastoma (Rb), CDK1, and cyclin-dependent kinase inhibitors p21 and p27. Interestingly, Lebein-induced apoptosis of colon cancer cells was dependent on their p53 status. Thus, in LS174 cells, cell death was associated with PARP cleavage and the activation of caspases 3 and 8 while in HCT116 cells, Lebein induced caspase-independent apoptosis through increased expression of apoptosis inducing factor (AIF). In LS174 cells, Lebein triggers the activation of the MAPK ERK1/2 pathway through induction of reactive oxygen species (ROS). It also decreased cell adhesion and migration to fibronectin through down regulation of α5β1 integrin. Moreover, Lebein significantly reduced the expression of two angiogenesis stimulators, Vascular Endothelial Growth Factor (VEGF) and Neuropilin 1 (NRP1). It inhibited the VEGF-induced neovascularization process in the quail embryonic CAM system and blocked the development of human colon adenocarcinoma in nude mice. Overall, our work indicates that Lebein may be useful to design a new therapy against colon cancer. © 2016 Wiley Periodicals, Inc.

Mycosynthesis of silver nanoparticles from Beauveria bassiana and its larvicidal, antibacterial, and cytotoxic effect on human cervical cancer (HeLa) cells

This paper deals with the synthesis, characterization and biological activities (mosquitocidal, antibacterial and cytotoxicity of cancer cells) of silver nanoparticles from the native entomopathogenic fungusBeauveria bassiana.

The beneficial effect of Zinc(II) on low-dose chemotherapeutic sensitivity involves p53 activation in wild-type p53-carrying colorectal cancer cells

BACKGROUND

Activation of wild-type p53 in response to genotoxic stress occurs through different mechanisms including protein conformation, posttranslational modifications, and nuclear localization, leading to DNA binding to sequence-specific promoters. Zinc ion plays a crucial role in stabilizing p53/DNA binding to induce canonical target genes. Mutant p53 proteins undergo protein misfolding that can be counteracted by zinc. However, whether zinc supplementation might have a beneficial antitumor effect in wild-type p53-carrying cells in combination with drugs, has not been addressed so far.

METHODS

In this study we compared the effect of two antitumor treatments: on the one hand wild-type p53-carrying colon cancer cells were treated with low and high doses of chemotherapeutic agent Adriamycin and, on the other hand, Adriamycin was used in combination with ZnCl2. Biochemical and molecular analyses were applied to evaluate p53 activity and biological outcomes in this setting. Finally, the effect of the different combination treatments were applied to assess tumor growth in vivo in tumor xenografts.

RESULTS

We found that low-dose Adriamycin did not induce p53 activation in wtp53-carrying colon cancer cells, unless in combination with ZnCl2. Mechanistically, ZnCl2 was a key determinant in inducing wtp53/DNA binding and transactivation of target genes in response to low-dose Adriamycin that used alone did not achieve such effects. Finally, in vivo studies, in a model of wtp53 colon cancer xenograft, show that low-dose Adriamycin did not induce tumor regression unless in combination with ZnCl2 that activated endogenous wtp53.

CONCLUSIONS

These results provide evidence that ZnCl2 might be a valuable adjuvant in chemotherapeutic regimens of colorectal cancer harboring wild-type p53, able to both activate p53 and reduce the amount of drugs for antitumor purposes.

Antiproliferative and Apoptosis Inducing Effects of Non-Polar Fractions from Lawsonia inermis L. in Cervical (HeLa) Cancer Cells

Two non-polar fractions viz. hexane (Hex-LI) and chloroform fraction (CHCl3-LI) of Lawsonia inermis were studied for their antiproliferative potential in various cancer cell lines viz. HeLa, MCF-7, A549 and C6 glioma cells. Both the fractions showed more than 60 % of growth inhibition in all the tested cell lines at highest tested concentration. In clonogenic assay, different concentrations of Hex-LI and CHCl3-LI decreased the number and size of colonies as compared to control in HeLa cells. The apoptotic effects as nuclear condensation, fragmentation were visualized with Hoechst-33342 staining of HeLa cells using confocal microscope. Both fractions induced apoptotic cell death in human cervical carcinoma (HeLa) cells as evident from flow cytometric analysis carried out using Annexin V-FITC and propidium iodide dyes. CHCl3-LI treated cells significantly induced apoptosis (25.43 %) in comparison to control. Results from Neutral Comet assay demonstrated that both fractions induced double stranded breaks (DSB's) in HeLa cells. Our data indicated that Hex-LI and CHCl3-LI treated cells showed significant increase of 32.2 and 18.56 % reactive oxygen species (ROS) levels in DCFH-DA assay respectively. Further, experimental studies to decipher exact pathway via which these fractions induce cell death are in progress.

The novel heterocyclic trioxirane [(1,3,5-tris oxiran-2-yl)methyl)-1,3,5-triazinane-2,4,6-trione (TATT)] exhibits a better anticancer effect than platinum-based chemotherapy by induction of apoptosis and curcumin further enhances its chemosensitivity

The heterocyclic trioxirane compound [1,3,5-tris((oxiran-2-yl)methyl)-1,3,5-triazinane-2,4,6-trione (TATT)] is a synthetic compound which has been used as an experimental anticancer agent in human clinical trials. Curcumin, an active natural compound in turmeric and curry, is an ingredient commonly used in the traditional diet of many Asian countries. In the present study, we observed that TATT exhibited a better anticancer effect on chemoresistant human colorectal cancer HT-29 cells and displayed less cytotoxicity on normal human umbilical vein endothelial cells, compared with FDA-approved anticancer drugs (cisplatin, carboplatin, or oxaliplatin) using MTT assay. TATT also induced a stronger apoptotic effect than that seen with the three studied anticancer drugs, as characterized by externalization of phosphatidylserine using flow cytometry. Administration of caspase 8-specific inhibitor (z-IETD-fmk) and mitochondrial permeability transition pore inhibitor (cyclosporin A) demonstrated that TATT-induced apoptosis proceeded via both extrinsic and intrinsic signaling pathways. It is noteworthy that coadministration of curcumin further significantly increased TATT-induced cytotoxicity, externalization of phosphatidylserine (representing early apoptosis), and the percentages of cells at the sub-G1 phase (representing late apoptosis), producing an additivity and/or synergistic effect, and vice versa. Suppression of nuclear NF-κB was involved in curcumin-enhanced chemosensitivity of TATT. Overall, our data indicate that TATT exerts a chemotherapeutic effect on colorectal cancer cells and coadministration of curcumin enhances the treatment effect of TATT.

Ellagic acid inhibits proliferation and induced apoptosis via the Akt signaling pathway in HCT-15 colon adenocarcinoma cells

Chemoprevention is regarded as one of the most promising and realistic approaches in the prevention of human cancer. Ellagic acid (EA) has been known for its chemopreventive activity against various cancers and numerous investigations have shown its apoptotic activity both in vivo and in vitro. The present study was focused to elucidate the anticancerous effect and the mode of action of EA against HCT-15 colon adenocarcinoma cells. Cell viability was assessed using trypan blue assay at different concentrations. EA also promoted cell cycle arrest substantially at G2/M phase in HCT-15 cells. The activities of alkaline phosphatase and lactate dehydrogenase were decreased upon EA treatment, which shows the antiproliferative and the cytotoxic effects, respectively. The production of reactive oxygen intermediates, which were examined by 2,7-dichlorodihydrofluorescein diacetate (H2DCF-DA), increased with time, after treatment with EA. In further studies, EA inhibited proliferation-associated markers proliferating cell nuclear antigen and cyclin D1. The induction of apoptosis was accompanied by a strong inactivation of phosphatidylinositol 3-kinase (PI3K)/Akt pathway by EA. The expression of PI3K and pAkt was down-regulated in EA-treated cells, compared to normal cells. Further, EA promoted the expression of Bax, caspase-3, and cytochrome c, and suppression of Bcl-2 activity in HCT-15 cells that was determined by western blot analysis. Increased annexin V apoptotic cells and DNA fragmentation also accompanied EA-induced apoptosis. In conclusion, EA increased the production of ROS, decreased cell proliferation, and induced apoptosis in HCT-15 cells, and thus can be used as an agent against colon cancer.

Genotypic characteristics of resistant tumors to pre-operative ionizing radiation in rectal cancer

Due to a wide range of clinical response in patients undergoing neo-adjuvant chemoradiation for rectal cancer it is essential to understand molecular factors that lead to the broad response observed in patients receiving the same form of treatment. Despite extensive research in this field, the exact mechanisms still remain elusive. Data raging from DNA-repair to specific molecules leading to cell survival as well as resistance to apoptosis have been investigated. Individually, or in combination, there is no single pathway that has become clinically applicable to date. In the following review, we describe the current status of various pathways that might lead to resistance to the therapeutic applications of ionizing radiation in rectal cancer.

The pro-apoptotic role of the regulatory feedback loop between miR-124 and PKM1/HNF4α in colorectal cancer cells

Accumulating evidence indicates that miRNA regulatory circuits play important roles in tumorigenesis. We previously reported that miR-124 is correlated with prognosis of colorectal cancer due to PKM-dependent regulation of glycolysis. However, the mechanism by which miR-124 regulates apoptosis in colorectal cancer remains largely elusive. Here, we show that miR-124 induced significant apoptosis in a panel of colorectal cancer cell lines. The mitochondrial apoptosis pathway was activated by miR-124. Furthermore, the pro-apoptotic role of miR-124 was dependent on the status of PKM1/2 level. PKM1 was required for miR-124-induced apoptosis. Via direct protein-protein interaction, PKM1 promoted HNF4α binding to the promoter region of miR-124 and transcribing miR-124. Moreover, HNF4α or PKM1 had a more dramatic effect on colorectal cancer cell apoptosis in the presence of miR-124. However, inhibition of miR-124 blocked cell apoptosis induced by HNF4α or PKM1. These data indicate that miR-124 not only alters the expression of genes involved in glucose metabolism but also stimulates cancer cell apoptosis. In addition, the positive feedback loop between miR-124 and PKM1/HNF4α plays an important role in colorectal cancer cell apoptosis; it suggests that disrupting this regulatory circuit might be a potential therapeutic tool for colorectal cancer treatment.

Polyamidoamine dendrimer liposome-mediated survivin antisense oligonucleotide inhibits hepatic cancer cell proliferation by inducing apoptosis

Polyamidoamine dendrimer (PAMAM) is a new nanometer material, which can transfer the target genes to cells with high efficiency and lower toxicity. This study aims to evaluate antitumor effects of survivin antisense oligonucleotide (survivin-asODN) (carried by polyamidoamine dendrimer liposome) on hepatic cancer in nude mice. Hepatic cancer model was established by injecting SMMC-7721 cells subcutaneously into flanks of nude mice. Polyamidoamine dendrimer and liposome were mixed with survivin-asODN, respectively. The shape and size of complex were observed by transmission electron microscope, and zeta potential was measured by an analytical tool. Encapsulation efficiency and DNA loading level were determined by an ultraviolet spectrophotometer in centrifuging method. Expression of survivin in transplant tumor was measured by Western blotting. No significant difference appeared for diameter and envelopment ratio between PAMAM liposome-survivin-asODN and PAMAM-survivin-asODN (P > 0.05). Both zeta potential and transfection efficiency in PAMAM liposome-survivin-asODN were higher than that in PAMAM-survivin-asODN complex (P < 0.05). Expression of survivin protein and weight of tumors in transplanted tumors in PAMAM liposome-survivin-asODN group was less than that in PAMAM-survivin-asODN group (P < 0.05). Cell apoptosis rate in PAMAM liposome-survivin-asODN group was higher than that of PAMAM-survivin-asODN group (P < 0.05). In conclusion, polyamidoamine dendrimer liposome can deliver survivin-asODN into hepatic transplanted tumor cells effectively. Ployamidoamine dendrimer liposome-mediated survivin-asODN can inhibit hepatic cell proliferation by inducing apoptosis.

Association of visceral obesity and early colorectal neoplasia

AIM: To examine whether visceral adipose tissue (VAT) serves as a risk factor for colorectal adenoma-early colorectal cancer (CRC) sequence.

METHODS: A retrospective case-control study was conducted with 153 patients with stage I CRC, age/sex-matched 554 patients with colorectal adenoma and 557 normal controls. All subjects underwent various laboratory tests, abdominal fat computed tomography (CT), and colonoscopy. VAT was defined as an intra-abdominal adipose tissue area measured by CT scan. Adipose tissue area was measured at the level of the umbilicus from CT scan. We used the lowest quartile of VAT and subcutaneous adipose tissue area as a reference group.

RESULTS: The body mass index (BMI), total cholesterol, fasting glucose and VAT areas were significantly different among normal, adenoma and CRC groups. The VAT area was 120.6 ± 49.0 cm² in normal controls, 130.6 ± 58.4 cm² in adenoma group and 117.6 ± 51.6 cm² in CRC group (P = 0.002). In univariate analysis, increased BMI was a risk factor for CRC compared to control (P = 0.025). However, VAT area was not a risk factor for CRC compared to control. In multivariate analysis that adjusted for smoking, alcohol consumption and subcutaneous adipose tissue area, VAT area was inversely related to CRC, compared to the adenoma (OR = 0.53, 95%CI: 0.31-0.92, highest quartile vs lowest quartile).

CONCLUSION: Our study shows that visceral obesity is not a risk factor for early CRC. Visceral obesity might influence the normal-adenoma sequence but not the adenoma-early carcinoma sequence.

Implications of Bit1 and AIF overexpressions in esophageal squamous cell carcinoma

Overwhelming evidence has demonstrated that Bit1 and AIF as mitochondrial proteins are implicated in the development and progression of a variety of tumors. However, their expressions and biological functions in esophageal squamous cell carcinoma (ESCC) remain to be delineated. In the present study, we found that Bit1, AIF, and Bcl-2 levels in ESCC tissues were significantly higher than those in normal esophageal epithelial tissues and dysplasia tissues (P < 0.05). Stepwise investigation demonstrated that Bit1 and Bcl-2 levels were both tightly associated with lymphatic metastasis and TNM staging (P < 0.05), and the levels of Bit1 mRNA as well as AIF and Bcl-2 proteins were both closely related to tumor differentiation (P < 0.05), but not related to the patients' age and gender (P > 0.05). Importantly, Bit1 mRNA and protein levels in ESCC with lymphatic metastasis and TNM staging in III and IV were markedly higher than that without lymphatic metastasis and TMN staging in I and II. Further analysis showed that expression of Bit1 protein was both positively correlated with expressions of AIF and Bcl-2 proteins (r = 0.408 and 0.405, respectively; P < 0.05). Correctively, our data cited earlier suggest that Bit1 plays pivotal roles in the development and progression of ESCC, and its biological functions in ESCC may be closely associated with AIF and Bcl-2 levels.

Cytotoxic Activity of Kenaf Seed Oils from Supercritical Carbon Dioxide Fluid Extraction towards Human Colorectal Cancer (HT29) Cell Lines

Kenaf (Hibiscus cannabinus) from the family Malvaceae, is a valuable fiber plant native to India and Africa and is currently planted as the fourth commercial crop in Malaysia. Kenaf seed oil contains alpha-linolenic acid, phytosterol such as β-sitosterol, vitamin E, and other antioxidants with chemopreventive properties. Kenaf seeds oil (KSO) was from supercritical carbon dioxide extraction fluid (SFE) at 9 different permutations of parameters based on range of pressures from 200 to 600 bars and temperature from 40 to 80°C. They were 200/40, 200/60, 200/80, 400/40, 400/60, 400/80, 600/40, 600/60, and 600/80. Extraction from 9 parameters of KSO-SFE was screened for cytotoxicity towards human colorectal cancer cell lines (HT29) and mouse embryonic fibroblast (NIH/3T3) cell lines using MTS assay. KSO-SFE at 600/40 showed the strongest cytotoxicity towards HT29 with IC₅₀ of 200 µg/mL. The IC₅₀ for NIH/3T3 was not detected even at highest concentration employed. Cell cycle analysis showed a significant increase in the accumulation of KSO-SFE-treated cells at sub-G1 phase, indicating the induction of apoptosis by KSO-SFE. Further apoptosis induction was confirmed by Annexin V/PI and AO/PI staining.

Anacardic acid induces mitochondrial-mediated apoptosis in the A549 human lung adenocarcinoma cells

Anacardic acid (AA) is a constituent of the cashew nut shell and is known as an inhibitor of nuclear factor-κB (NF-κB). We investigated the cytotoxicity of AA on cancer cells and more experiments to reveal the cell death mechanism focused on A549 lung adenocarcinoma cells for our interest in lung cancer. To examine the molecular mechanism of cell death in AA treated A549 cells, we performed experiments such as transmission electron microscopy (TEM), western blot analysis, fluorescence-activated cell sorting (FACS), genomic DNA extraction and staining with 4',6-diamidino-2-phenylindole (DAPI). For the first time we revealed that AA induces caspase-independent apoptosis with no inhibition of cytotoxicity by pan-caspase inhibitor, Z-VAD-fmk, in A549 cells. Our results showed the possibility of mitochondrial-mediated apoptosis through the activation of apoptosis-inducing factor (AIF) and an intrinsic pathway executioner such as cytochrome c. This study will be helpful in revealing the cell death mechanisms and in developing potential drugs for lung cancer using AA.

The enzymatic activity of apoptosis-inducing factor supports energy metabolism benefiting the growth and invasiveness of advanced prostate cancer cells

Apoptosis-inducing factor (AIF) promotes cell death yet also controls mitochondrial homeostasis and energy metabolism. It is unclear how these activities are coordinated, and the impact of AIF upon human disease, in particular cancer, is not well documented. In this study we have explored the contribution of AIF to the progression of prostate cancer. Analysis of archival gene expression data demonstrated that AIF transcript levels are elevated in human prostate cancer, and we found that AIF protein is increased in prostate tumors. Suppression of AIF expression in the prostate cancer cell lines LNCaP, DU145, and PC3 demonstrated that AIF does not contribute to cell toxicity via a variety of chemical death triggers, and growth under nutrient-rich conditions is largely unaffected by AIF ablation. However, under growth stress conditions, AIF depletion from DU145 and PC3 cell lines led to significant reductions in cell survival and growth that were not observed in LNCaP cells. Moreover AIF-deficient PC3 cells exhibited substantial reduction of tumorigenic growth in vivo. This reduced survival correlated with decreased expression of mitochondrial complex I protein subunits and concomitant changes in glucose metabolism. Finally, restoration of AIF-deficient PC3 cells with AIF variants demonstrated that the enzymatic activity of AIF is required for aggressive growth. Overall these studies show that AIF is an important factor for advanced prostate cancer cells and that through control of energy metabolism and redox balance, the enzymatic activity of AIF is critical for this support.

Role of apoptosis-inducing factor, proline dehydrogenase, and NADPH oxidase in apoptosis and oxidative stress

Flavoproteins catalyze a variety of reactions utilizing flavin mononucleotide or flavin adenine dinucleotide as cofactors. The oxidoreductase properties of flavoenzymes implicate them in redox homeostasis, oxidative stress, and various cellular processes, including programmed cell death. Here we explore three critical flavoproteins involved in apoptosis and redox signaling, ie, apoptosis-inducing factor (AIF), proline dehydrogenase, and NADPH oxidase. These proteins have diverse biochemical functions and influence apoptotic signaling by unique mechanisms. The role of AIF in apoptotic signaling is two-fold, with AIF changing intracellular location from the inner mitochondrial membrane space to the nucleus upon exposure of cells to apoptotic stimuli. In the mitochondria, AIF enhances mitochondrial bioenergetics and complex I activity/assembly to help maintain proper cellular redox homeostasis. After translocating to the nucleus, AIF forms a chromatin degrading complex with other proteins, such as cyclophilin A. AIF translocation from the mitochondria to the nucleus is triggered by oxidative stress, implicating AIF as a mitochondrial redox sensor. Proline dehydrogenase is a membrane-associated flavoenzyme in the mitochondrion that catalyzes the rate-limiting step of proline oxidation. Upregulation of proline dehydrogenase by the tumor suppressor, p53, leads to enhanced mitochondrial reactive oxygen species that induce the intrinsic apoptotic pathway. NADPH oxidases are a group of enzymes that generate reactive oxygen species for oxidative stress and signaling purposes. Upon activation, NADPH oxidase 2 generates a burst of superoxide in neutrophils that leads to killing of microbes during phagocytosis. NADPH oxidases also participate in redox signaling that involves hydrogen peroxide-mediated activation of different pathways regulating cell proliferation and cell death. Potential therapeutic strategies for each enzyme are also highlighted.

5-Fluorouracil-loaded poly(ε-caprolactone) nanoparticles combined with phage E gene therapy as a new strategy against colon cancer

This work aimed to develop a new therapeutic approach to increase the efficacy of 5-fluorouracil (5-FU) in the treatment of advanced or recurrent colon cancer. 5-FU-loaded biodegradable poly(ε-caprolactone) nanoparticles (PCL NPs) were combined with the cytotoxic suicide gene E (combined therapy). The SW480 human cancer cell line was used to assay the combined therapeutic strategy. This cell line was established from a primary adenocarcinoma of the colon and is characterized by an intrinsically high resistance to apoptosis that correlates with its resistance to 5-FU. 5-FU was absorbed into the matrix of the PCL NPs during synthesis using the interfacial polymer disposition method. The antitumor activity of gene E from the phage ϕX174 was tested by generating a stable clone (SW480/12/E). In addition, the localization of E protein and its activity in mitochondria were analyzed. We found that the incorporation of 5-FU into PCL NPs (which show no cytotoxicity alone), significantly improved the drug's anticancer activity, reducing the proliferation rate of colon cancer cells by up to 40-fold when compared with the nonincorporated drug alone. Furthermore, E gene expression sensitized colon cancer cells to the cytotoxic action of the 5-FU-based nanomedicine. Our findings demonstrate that despite the inherent resistance of SW480 to apoptosis, E gene activity is mediated by an apoptotic phenomenon that includes modulation of caspase-9 and caspase-3 expression and intense mitochondrial damage. Finally, a strongly synergistic antiproliferative effect was observed in colon cancer cells when E gene expression was combined with the activity of the 5-FU-loaded PCL NPs, thereby indicating the potential therapeutic value of the combined therapy.

Effect of extracts from Phyllanthus watsonii Airy Shaw on cell apoptosis in cultured human breast cancer MCF-7 cells

Species of Phyllanthus have traditionally been used for hundreds of years for treating many ailments including diabetes, anemia, bronchitis and hepatitis. The present study aims to investigate the cytotoxic and apoptotic effects of methanol (PWM), hexane (PWH) and ethyl acetate (PWE) extracts from the leaves of the endemic plant Phyllanthus watsonii Airy Shaw (Phyllanthaceae) on MCF-7 human breast cancer cells. We observed that the PWM, PWH and PWE extracts were cytotoxic and selectively inhibited the growth and proliferation of MCF-7 cells compared to untreated control in a dose dependent manner with an IC(50) of 12.7 ± 4.65, 7.9 ± 0.60 and 7.7 ± 0.29 μg/ml, respectively. However, the extracts were not toxic at these concentrations to normal human lung fibroblast MRC-5 cells. Cell death induced by PWM, PWH and PWE extracts were mainly due to apoptosis which was characterized by apoptotic morphological changes and a nuclear DNA fragmentation. Caspase-3 activation following P. watsonii extracts treatment was also evident for apoptotic cell death which was preceded by an S phase cell cycle perturbation. The results suggested that the cytotoxic activity of P. watsonii extracts was related to an early event of cell cycle perturbation and a later event of apoptosis. Hence, P. watsonii displays potential to be further exploited in the discovery and development of new anticancer agents.

Isoegomaketone induces apoptosis through caspase-dependent and caspase-independent pathways in human DLD1 cells

Isoegomaketone (IK) is an essential oil component of Perilla frutescens (L.), but the mechanism by which IK induces apoptosis has never been studied. The purpose of this study was to elucidate the IK-induced apoptotic pathway in DLD1 human colon cancer cells. We observed that IK treatment over 24 h significantly inhibited cell viability in a dose-dependent manner. We also found that IK triggered cleavage of PARP. Moreover, IK treatment resulted in cleavage of caspase-8, -9, and -3 in a dose- and time-dependent manner. IK treatment also resulted in cleavage of Bid and translocation of Bax, and triggered the release of cytochrome c from the mitochondria to the cytoplasm. Furthermore, it resulted in the translocation of apoptosis inducing factor (AIF), a caspase-independent mitochondrial apoptosis factor, from the mitochondria into the nucleus. Overall, these results suggest that IK induces apoptosis through caspase-dependent and capase-independent pathways in DLD1 cells.

Modulation of Bcl-2-related protein expression in pancreatic beta cells by pro-inflammatory cytokines and its dependence on the antioxidative defense status

Pro-inflammatory cytokines are key mediators in the selective and progressive destruction of insulin-producing beta cells during type 1 diabetes development. However, the mechanisms of cytokine-induced beta cell apoptosis are not fully understood. This study demonstrates that pro-inflammatory cytokines strongly modified the expression of the anti-apoptotic protein Bcl-2 and the pro-apoptotic BH3-only proteins Bad, Bim, and Bid in primary rat islets and insulin-producing RINm5F cells. Overexpression of mitochondrially located catalase (MitoCatalase) specifically increased basal Bcl-2 and decreased basal Bax expression, suppressed cytokine-mediated reduction of Bcl-2, and thereby prevented the release of cytochrome c, Smac/DIABLO and the activation of caspase-9 and -3. Thus, cytokine-mediated decrease of Bcl-2 expression and the sequentially changed Bax/Bcl-2 ratio are responsible for the release of pro-apoptotic mitochondrial factors, activation of caspase-9, and ultimately caspase-3. These results indicate that activation of the intrinsic/mitochondrial apoptosis pathway is essential for cytokine-induced beta cell death and the mitochondrial generation of reactive oxygen species, in particular mitochondrial hydrogen peroxide, differentially regulates the Bax/Bcl-2 ratio.