Folic acid-mediated inhibition of serum-induced activation of EGFR promoter in colon cancer cells

Evaluation of Methylation Profiles of An Epidermal Growth Factor Receptor Gene in a Head and Neck Squamous Cell Carcinoma Patient Group

Upregulation of the epidermal growth factor receptor (EGFR) gene has shown an important impact on the development of head and neck cancers due to its important regulation role on multiple cell signaling pathways. The aim of this study was to investigate the methylation pattern of the promoter region of the EGFR gene between head and neck squamous cell carcinoma (HNSCC) patients and a control group. Forty-seven unrelated HNSCC patients, clinically diagnosed at the Department of Otorhinolaryngology, Dışkapı Yıldırım Beyazıt Training and Research Hospital, Ankara, Turkey, and 48 unrelated healthy volunteers from different geographic regions of Turkey, were included in this study. Methylation status of the promoter region of the EGFR gene was detected by methylation-specific-polymerase chain reaction (MS-PCR). The correlation between EGFR gene promoter methylation profiles and clinical characteristics were examined using the χ² test. Methylation was observed in 79.0% of HNSCC patients, whereas this ratio was 90.0% in healthy individuals. The results show that promoter region methylation of the EGFR gene was not associated with HNSCC development in the studied Turkish patient group. In addition, the methylation status of the EGFR gene promoter was not found to be related to age, gender or tumor stage.

The role of primary tumour sidedness, EGFR gene copy number and EGFR promoter methylation in RAS/BRAF wild-type colorectal cancer patients receiving irinotecan/cetuximab

BACKGROUND

The data from randomised trials suggested that primary tumour sidedness could represent a prognostic and predictive factor in colorectal cancer (CRC) patients, particularly during treatment with anti-epidermal growth factor receptor (EGFR) therapy. However, an in-deep molecular selection might overcome the predictive role of primary tumour location in this setting.

METHODS

We conducted a retrospective analysis in which tumour samples from RAS/BRAF wild-type (WT) metastatic CRC patients treated with second-third-line irinotecan/cetuximab were analysed for EGFR gene copy number (GCN) and promoter methylation. Study objective was to evaluate the correlation of tumour sidedness, EGFR promoter methylation and EGFR GCN with clinical outcome. Median follow-up duration was 14.3 months.

RESULTS

Eighty-eight patients were included in the study, 27.3% had right-sided CRC, 72.7% had left-sided CRC; 36.4% had EGFR GCN<2.12 tumour, 63.6% had EGFR GCN⩾2.12 tumour; 50% had EGFR promoter-methylated tumour. Right-sided colorectal cancer (RSCRC) were associated with reduced overall response rate (ORR) (4.2% for RSCRC vs 35.9% for left sided colorectal cancer (LSCRC), P=0.0030), shorter progression-free survival (PFS) (3.0 vs 6.75 months, P<0.0001) and shorter overall survival (OS) (8 vs 13.6 months, P<0.0001). EGFR GCN<2.12 tumours were associated with reduced ORR (6.2% for EGFR GCN<2.12 vs 39.3% for EGFR GCN⩾2.12 tumours, P=0.0009), shorter PFS (3.5 vs 6.5 months, P=0.0006) and shorter OS (8.5 vs 14.0 months, P<0.0001). Epidermal growth factor receptor-methylated tumours were associated with reduced ORR (9.1% for methylated vs 45.5% for unmethylated, P=0.0001), shorter PFS (3 vs 7.67 months, P<0.0001) and shorter OS (8 vs 17 months, P<0.0001). At multivariate analysis, EGFR GCN and EGFR promoter methylation maintained their independent role for ORR (respectively P=0.0082 and 0.0025), PFS (respectively P=0.0048 and<0.0001) and OS (respectively P=0.0001 and<0.0001).

CONCLUSIONS

In our study, an accurate molecular selection based on an all RAS and BRAF analysis along with EGFR GCN and EGFR promoter methylation status seems to be more relevant than primary tumour sidedness in the prediction of clinical outcome during cetuximab/irinotecan therapy. However, these data need to be validated with future prospective and translational studies.

Loss of EGF-dependent cell proliferation ability on radioresistant cell HepG2-8960-R

Acquired radioresistance of cancer cells interferes with radiotherapy and increases the probability of cancer recurrence. HepG2-8960-R, which is one of several clinically relevant radioresistant (CRR) cell lines, has a high tolerance to the repeated clinically relevant doses of X-ray radiation. In this study, HepG2-8960-R had slightly lower cell proliferation ability than HepG2 in the presence of FBS. In particular, epidermal growth factor (EGF) hardly enhanced cell proliferation and DNA synthesis in HepG2-8960-R. Additionally, EGF could not induce the activation of Erk1/2, because the expression of EGF receptor (EGFR) protein decreased in HepG2-8960-R in accordance with the methylation of the EGFR promoter region. Therefore, cetuximab did not inhibit HepG2-8960-R cell proliferation. Our study showed that HepG2-8960-R had radioresistant and cetuximab-resistant abilities.

Blockade of DNA methylation enhances the therapeutic effect of gefitinib in non-small cell lung cancer cells

The sensitivity of lung cancer to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) has been found to be associated with mutations in the tyrosine kinase domain of EGFR. However, not all mutations are sensitive to gefitinib. While CpG island methylation in the promoter region of the EGFR gene and transcriptional silencing are common in solid tumors, the role of the EGFR gene promoter methylation in affecting resistance to TKIs in non-small cell lung cancer (NSCLC) remains unknown. In this study, we examined the correlation between EGFR gene promoter methylation and the therapeutic effect of gefitinib in NSCLC cells. Three NSCLC cell lines with different EGFR mutation statuses and levels of sensitivity to EGFR-TKIs were used in this study: H1650 (del E746-A750), H1299 (wild-type EGFR) and PC-9 (del E746-A750). Cells were treated with gefitinib or 5-aza-2'-deoxy cytidine (5-aza-CdR), a methylation inhibitor, alone or in combination. Subsequently, the methylation status of the EGFR gene promoter was examined by methylation-specific PCR (MSP). Cell survival and apoptosis assays were performed using the Cell Counting Kit-8 (CCK-8) and flow cytometry. In addition, western blot analysis and quantitative real-time PCR were used to examine the expression levels of EGFR protein and mRNA. Our study showed that the promoter region of the EGFR gene in PC-9 cells was unmethylated, and that the cells were sensitive to gefitinib. By contrast, the promoter region of the EGFR gene in the H1650 and H1299 cells was methylated, and the cells were resistant to gefitinib. Of note, the combination treatment with 5-aza-CdR and gefitinib further enhanced the growth inhibitory effects and led to the induction of apoptosis, while a significant reduction in the expression of EGFR protein and mRNA was observed in the H1650 and H1299 cells. These results suggest that blockade of DNA methylation may enhance the antitumor effects of EGFR-TKIs and gefitinib in NSCLC cells. Thus, EGFR gene promoter methylation may be a potential mechanism for acquired resistance to gefitinib.

Elimination of Colon Cancer Stem-Like Cells by the Combination of Curcumin and FOLFOX

5-Fluorouracil (5-FU) or 5-FU plus oxaliplatin (FOLFOX) remains the backbone of colorectal cancer chemotherapeutics but with limited success. This could partly be due to the enrichment of cancer stem cells (CSCs) that are resistant to conventional chemotherapy. Therefore, validation of a nontoxic agent that can either cause reversal of chemoresistance or promote the killing of CSCs would be highly desirable. The current study examines whether curcumin, the major active ingredient of turmeric, either alone or together with FOLFOX, would be an effective strategy to eliminate colon CSCs. Exposure of colon cancer HCT-116 or HT-29 cells to FOLFOX that inhibited their growth led to the enrichment of CSC phenotype as evidenced by increased proportion of CD133-, CD44-, and/or CD166-positive cells and epidermal growth factor receptor (EGFR) levels. Treatment of FOLFOX-surviving colon cancer cells with either curcumin alone or together with FOLFOX resulted in a marked reduction in CSCs, as evidenced by the decreased expression of CD44 and CD166 as well as EGFR and by their ability to form anchorage-dependent colonies. They also caused disintegration of colonospheres. Increased expression of EGFR in FOLFOX-surviving cells could be attributed to hypomethylation of the EGFR promoter, whereas an opposite phenomenon was observed when the FOLFOX-surviving cells were treated with curcumin and/or FOLFOX. These changes were accompanied by parallel alterations in the levels of DNA methyltransferase 1. In conclusion, our data suggest that curcumin by itself or together with the conventional chemotherapeutic could be an effective treatment strategy for preventing the emergence of chemoresistant colon cancer cells by reducing/eliminating CSCs.

Epidermal growth factor receptor (EGFR) gene promoter methylation and cetuximab treatment in colorectal cancer patients

Background:

Epidermal growth factor receptor (EGFR) promoter methylation may be responsible for the loss of EGFR expression in neoplastic cells. The primary aim of our study was to verify a possible correlation between EGFR gene promoter methylation and clinical outcome in metastatic colorectal cancer patients receiving chemotherapy with irinotecan and cetuximab.

Methods:

Colorectal samples from patients treated with irinotecan–cetuximab were analysed for EGFR promoter methylation and EGFR immunohistochemistry.

Results:

Fifty-two patients were analysed. Thirty patients (58%) showed EGFR promoter hypermethylation. In EGFR promoter methylated and EGFR promoter unmethylated patients, we observed a partial response in 3 (10%) and 13 (59%) patients, respectively (P=0.03), progressive disease was obtained in 19 (63%) and 2 (9%) patients, respectively, with EGFR promoter methylated and EGFR promoter unmethylated tumours (P=0.0001). Median progression-free survival was 2.4 months in patients showing EGFR promoter methylated tumours and 7.4 months for those who had EGFR promoter unmethylated tumours (P<0.0001; Figure 1). Median overall survival was 6.1 months in patients showing EGFR promoter methylated tumours and 17.8 months for those who had EGFR promoter unmethylated tumours (P<0.0001; Figure 2). CONCLUSION:EGFR promoter hypermethylation, after confirmation in larger data set, may represent a valuable asset in further studies investigating EGFR as a therapeutic target in colorectal cancer.

Fooling mother nature: epigenetics and novel treatments for psychiatric disorders

Modern formulations of psychiatric disorders hypothesize that mother nature goes awry, causing both genetic and epigenetic disease actions. Genetic disease actions are the consequences of naturally inherited risk genes that have an altered sequence of DNA. This altered DNA sequence theoretically leads to the production of altered gene products in neurons, causing inefficient information processing in various brain circuits, and biasing those circuits towards developing symptoms of a mental illness. Epigenetic disease actions are theorized either to activate risk genes to make an altered gene product or to activate normal genes to make normal gene products but at the wrong time. Epigenetic disease mechanisms theoretically turn normal genes into risk genes by causing normal genes to be expressed in neurons when these genes should be silenced or by causing normal genes to be silenced when they should be expressed.

Methylated spirits: epigenetic hypotheses of psychiatric disorders

Our spirits may be regulated by the methylation of our genes. Methylation, acetylation, and other biochemical processes are the molecular switches for turning genes on and off. There is evidence now that certain behaviors, feelings, and psychiatric symptoms may be modified by turning various genes on or off. If classical genetics is the sequence of DNA that is inherited, then epigenetics is a parallel process determining whether a given gene (ie, a sequence of DNA coding for transcription) is expressed into its RNA or is silenced. Epigenetics is now entering psychiatry with the hypothesis that normal genes as well as risk genes can both contribute to a mental disorder. That is, it has long been hypothesized that when “abnormal” genes with an altered sequence of DNA are inherited as risk genes for a mental illness, these risk genes will make an abnormal gene product in neurons, contributing to inefficient information processing in various brain circuits and creating risk for developing a symptom of a mental illness. Now comes the role of epigenetic actions in mental illnesses.

Folic acid supplementation inhibits recurrence of colorectal adenomas: A randomized chemoprevention trial

AIM: To determine whether folic acid supplementation will reduce the recurrence of colorectal adenomas, the precursors of colorectal cancer, we performed a double-blind placebo-controlled trial in patients with adenomatous polyps.

METHODS: In the current double-blind, placebo-controlled trial at this VA Medical Center, patients with colorectal adenomas were randomly assigned to receive either a daily 5 mg dose of folic acid or a matched identical placebo for 3 years. All polyps were removed at baseline colonoscopy and each patient had a follow up colonoscopy at 3 years. The primary endpoint was a reduction in the number of recurrent adenomas at 3 years.

RESULTS: Of 137 subjects, who were eligible after confirmation of polyp histology and run-in period to conform compliance, 94 completed the study; 49 in folic acid group and 45 in placebo group. Recurrence of adenomas at 3-year was compared between the two groups. The mean number of recurrent polyps at 3-year was 0.36 (SD, 0.69) for folic acid treated patients compared to 0.82 (SD, 1.17) for placebo treated subjects, resulting in a 3-fold increase in polyp recurrence in the placebo group. Patients below 70 years of age and those with left-sided colonic adenomas or advanced adenomas responded better to folic acid supplementation.

CONCLUSION: High dose folic acid supplementation is associated with a significant reduction in the recurrence of colonic adenomas suggesting that folic acid may be an effective chemopreventive agent for colorectal neoplasia.

Cell cycle and apoptosis regulatory protein-1: a novel regulator of apoptosis in the colonic mucosa during aging

Although the regulatory mechanisms for the age-related rise in proliferation and reduction in apoptosis in the colonic mucosa are yet to be fully delineated, we have demonstrated that these events are associated with increased expression and activation of epithelial growth factor receptor (EGFR)/ErbB-1 and some of its receptor family members (EGFRs), indicating their involvement in these processes. However, the downstream signaling events of EGFR and/or its family members regulating age-related changes in mucosal proliferation and apoptosis remain to be delineated. Cell cycle and apoptosis regulatory protein-1 (CARP-1), a novel growth signaling regulator that we isolated, participates in EGFR-dependent signaling. In the current investigation, we examined the involvement of CARP-1 in colonic mucosal growth-related processes during aging. We report that the age-related reduction in apoptosis in the colonic mucosa is associated with increased expression and tyrosine phosphorylation of not only EGFR but also ErbB-2 and ErbB-3. In contrast, protein and mRNA levels of CARP-1 as well as tyrosine phosphorylation of CARP-1 are decreased. Additionally, we have observed that administration of wortmannin, an inhibitor of phosphatidylinositol 3-kinase activity that accelerates apoptosis in the colonic mucosa of aged rats, causes a marked increase in expression and tyrosine phosphorylation of CARP-1. The age-related decline in CARP-1 expression could partly be attributed to increased methylation of the CARP-1 promoter. Taken together, our data suggest that not only EGFR but also its other members are involved in regulating colonic mucosal growth during aging and that CARP-1 may play a crucial role in transducing EGFRs signals.

Transactivator of transcription-tagged cell cycle and apoptosis regulatory protein-1 peptides suppress the growth of human breast cancer cells in vitro and in vivo

Deregulated signaling by the epidermal growth factor receptor family of proteins is encountered in human malignancies including breast cancer. Cell cycle and apoptosis-regulatory protein-1 (CARP-1), a novel, perinuclear phosphoprotein, is a regulator of apoptosis signaling by epidermal growth factor receptors. CARP-1 expression is diminished in human breast cancers, and correlates inversely with human breast cancer grades which could be attributed to increased methylation. The expression of CARP-1, on the other hand, interferes with the ability of human breast cancer cells to invade through the matrigel-coated membranes, to form colonies in the soft agar, and to grow as s.c. tumors in severe combined immunodeficiency (SCID) mice. To test whether CARP-1 is a suppressor of human breast cancer growth, we generated transactivator of transcription (TAT)-tagged CARP-1 peptides. Treatment of human breast cancer cells with affinity purified, TAT-CARP-1 1-198, 197-454, and 896-1150 peptides caused inhibition of human breast cancer cell proliferation and elevated apoptosis. In contrast, TAT-tagged enhanced green fluorescent protein or CARP-1 (1-198(Y192/F)) peptide failed to inhibit cell proliferation or induce apoptosis. Apoptosis by CARP-1 peptides, with the exception of CARP-1 (1-198(Y192/F)), involves the activation of p38 stress-activated protein kinase and caspase-9. Moreover, administration of TAT-CARP-1 (1-198), but not TAT-tagged enhanced green fluorescent protein or TAT-CARP-1 (1-198(Y192/F)), inhibits growth of human breast cancer cell-derived tumor xenografts in SCID mice. We conclude that CARP-1 is a suppressor of human breast cancer growth, and its expression is diminished in tumors, in part, by methylation-dependent silencing.

The Wnt-dependent signaling pathways as target in oncology drug discovery

Our current understanding of the Wnt-dependent signaling pathways is mainly based on studies performed in a number of model organisms including, Xenopus, Drosophila melanogaster, Caenorhabditis elegans and mammals. These studies clearly indicate that the Wnt-dependent signaling pathways are conserved through evolution and control many events during embryonic development. Wnt pathways have been shown to regulate cell proliferation, morphology, motility as well as cell fate. The increasing interest of the scientific community, over the last decade, in the Wnt-dependent signaling pathways is supported by the documented importance of these pathways in a broad range of physiological conditions and disease states. For instance, it has been shown that inappropriate regulation and activation of these pathways is associated with several pathological disorders including cancer, retinopathy, tetra-amelia and bone and cartilage disease such as arthritis. In addition, several components of the Wnt-dependent signaling pathways appear to play important roles in diseases such as Alzheimer’s disease, schizophrenia, bipolar disorder and in the emerging field of stem cell research. In this review, we wish to present a focused overview of the function of the Wnt-dependent signaling pathways and their role in oncogenesis and cancer development. We also want to provide information on a selection of potential drug targets within these pathways for oncology drug discovery, and summarize current data on approaches, including the development of small-molecule inhibitors, that have shown relevant effects on the Wnt-dependent signaling pathways.

Interleukin-6 contributes to growth in cholangiocarcinoma cells by aberrant promoter methylation and gene expression

The association between chronic inflammation and the development and progression of malignancy is exemplified in the biliary tract where persistent inflammation strongly predisposes to cholangiocarcinoma. The inflammatory cytokine interleukin-6 (IL-6) enhances tumor growth in cholangiocarcinoma by altered gene expression via autocrine mechanisms. IL-6 can regulate the activity of DNA methyltransferases, and moreover, aberrant DNA methylation can contribute to carcinogenesis. We therefore investigated the effect of chronic exposure to IL-6 on methylation-dependent gene expression and transformed cell growth in human cholangiocarcinoma. The relationship between autocrine IL-6 pathways, DNA methylation, and transformed cell growth was assessed using malignant cholangiocytes stably transfected to overexpress IL-6. Treatment with the DNA methylation inhibitor 5-aza-2'-deoxycytidine decreased cell proliferation, growth in soft agar, and methylcytosine content of malignant cholangiocytes. However, this effect was not observed in IL-6-overexpressing cells. IL-6 overexpression resulted in the altered expression and promoter methylation of several genes, including the epidermal growth factor receptor (EGFR). EGFR promoter methylation was decreased and gene and protein expression was increased by IL-6. Thus, epigenetic regulation of gene expression by IL-6 can contribute to tumor progression by altering promoter methylation and gene expression of growth-regulatory pathways, such as those involving EGFR. Moreover, enhanced IL-6 expression may decrease the sensitivity of tumor cells to therapeutic treatments using methylation inhibitors. These observations have important implications for cancer treatment and provide a mechanism by which persistent cytokine stimulation can promote tumor growth.

Epidermal growth factor receptor–related peptide inhibits growth of PC-3 prostate cancer cells

Interference with the activation of growth factor receptors, specifically epidermal growth factor receptor (EGFR), represents a promising strategy for the development of novel and selective anticancer therapies. We reported that EGFR-related peptide (ERRP), a recently isolated negative regulator of EGFR, could be a potential therapeutic agent for colorectal cancer. To determine whether ERRP could potentially be a therapeutic agent for prostate carcinoma, we examined the effect of recombinant ERRP on the growth of the prostate cancer cell line PC-3 in vitro. Events of the EGFR signal transduction pathways were also examined. ERRP caused a marked inhibition of cell growth in a dose- and time-dependent manner and also induced apoptosis. The latter was evidenced by increased number of apoptotic cells, activation of caspase-3, and cleavage of poly(ADP-ribose)polymerase. The transforming growth factor-α–induced stimulation of cell growth and activation of EGFR was also inhibited by ERRP. These changes were accompanied by a concomitant attenuation of activation of Akt and mitogen-activated protein kinases as well as basal and transforming growth factor-α–induced activation of nuclear factor-κB. Inhibition of EGFR activation by ERRP could be partly attributed to increased sequestration of EGFR ligands. In summary, our data show that ERRP inhibits the growth of prostate cancer cells by attenuating EGFR signaling processes. ERRP could potentially be an effective therapeutic agent for prostate cancer.