Human Papillomavirus E6 Oncogenes Research Articles

Identification and characterization of HPV-independent cervical cancers.

BackgroundHuman papillomavirus (HPV) initiates cervical cancer, and continuous expression of HPV oncogenes E6 and E7 is thought to be necessary to maintain malignant growth. Current therapies target proliferating cells, rather than specific pathways, and most experimental therapies specifically target E6/E7. We investigated the presence and expression of HPV in cervical cancer, to correlate HPV oncogene expression with clinical and molecular features of these tumors that may be relevant to new targeted therapies.ResultsWhile virtually all cervical cancers contained HPV DNA, and most expressed E6/E7 (HPV-active), a subset (8%) of HPV DNA-positive cervical cancers did not express HPV transcripts (HPV-inactive). HPV-inactive tumors occurred in older women (median 54 vs. 45 years, p = 0.02) and were associated with poorer survival (median 715 vs 3046 days, p = 0.0003). Gene expression profiles of HPV-active and -inactive tumors were distinct. HPV-active tumors expressed E2F target genes and increased AKT/MTOR signaling. HPV-inactive tumors had increased WNT/β-catenin and Sonic Hedgehog signaling. Substantial genome-wide differences in DNA methylation were observed. HPV-inactive tumors had a global decrease in DNA methylation; however, many promoter-associated CpGs were hypermethylated. Many inflammatory response genes showed promoter methylation and decreased expression. The somatic mutation landscapes were significantly different. HPV-active tumors carried few somatic mutations in driver genes, whereas HPV-inactive tumors were enriched for non-synonymous somatic mutations (p-value < 0.0000001) specifically targeting TP53, ARID, WNT, and PI3K pathways.Materials and MethodsThe Cancer Genome Atlas (TCGA) cervical cancer data were analyzed.ConclusionsMany of the gene expression changes and somatic mutations found in HPV-inactive tumors alter pathways for which targeted therapeutics are available. Treatment strategies focused on WNT, PI3K, or TP53 mutations may be effective against HPV-inactive tumors and could improve survival for these cervical cancer patients.

Subtypes of HPV-Positive Head and Neck Cancers Are Associated with HPV Characteristics, Copy Number Alterations, PIK3CA Mutation, and Pathway Signatures.

There is substantial heterogeneity within human papillomavirus (HPV)-associated head and neck cancer (HNC) tumors that predispose them to different outcomes; however, the molecular heterogeneity in this subgroup is poorly characterized due to various historical reasons. We performed unsupervised gene expression clustering on deeply annotated (transcriptome and genome) HPV(+) HNC samples from two cohorts (84 total primary tumors), including 18 HPV(-) HNC samples, to discover subtypes and characterize the differences between subgroups in terms of their HPV characteristics, pathway activity, whole-genome somatic copy number alterations, and mutation frequencies. We identified two distinct HPV(+) subtypes (namely HPV-KRT and HPV-IMU). HPV-KRT is characterized by elevated expression of genes in keratinocyte differentiation and oxidation-reduction process, whereas HPV-IMU has strong immune response and mesenchymal differentiation. The differences in expression are likely connected to the differences in HPV characteristics and genomic changes. HPV-KRT has more genic viral integration, lower E2/E4/E5 expression levels, and higher ratio of spliced to full-length HPV oncogene E6 than HPV-IMU; the subgroups also show differences in copy number alterations and mutations, in particular the loss of chr16q in HPV-IMU and gain of chr3q and PIK3CA mutation in HPV-KRT. Our characterization of two subtypes of HPV(+) HNC tumors provides valuable molecular level information that point to two main carcinogenic paths. Together, these results shed light on stratifications of the HPV(+) HNCs and will help to guide personalized care for HPV(+) HNC patients. Clin Cancer Res; 22(18); 4735-45. ©2016 AACR.

Anticancer and Cytotoxic Potential of Turmeric (Curcuma longa), Neem (Azadirachta indica), Tulasi (Ocimum sanctum) and Ginger (Zingiber officinale) Extracts on HeLa cell line

Anticancer and Cytotoxic Potential of Turmeric (Curcuma longa), Neem (Azadirachta indica), Tulasi (Ocimum sanctum) and Ginger (Zingiber officinale) Extracts on HeLa cell line

Role of Cdc6 in re-replication in cells expressing human papillomavirus E7 oncogene.

The E7 oncoprotein of high-risk human papillomavirus (HPV) types induces DNA re-replication that contributes to carcinogenesis; however, the mechanism is not fully understood. To better understand the mechanism by which E7 induces re-replication, we investigated the expression and function of cell division cycle 6 (Cdc6) in E7-expressing cells. Cdc6 is a DNA replication initiation factor and exhibits oncogenic activities when overexpressed. We found that in E7-expressing cells, the steady-state level of Cdc6 protein was upregulated and its half-life was increased. Cdc6 was localized to the nucleus and associated with chromatin, especially upon DNA damage. Importantly, downregulation of Cdc6 reduced E7-induced re-replication. Interestingly, the level of Cdc6 phosphorylation at serine 54 (S54P) was increased in E7-expressing cells. S54P was associated with an increase in the total amount of Cdc6 and chromatin-bound Cdc6. DNA damage-enhanced upregulation and chromatin binding of Cdc6 appeared to be due to downregulation of cyclin-dependent kinase 1 (Cdk1) as Cdk1 knockdown increased Cdc6 levels. Furthermore, Cdk1 knockdown or inhibition led to re-replication. These findings shed light on the mechanism by which HPV induces genomic instability and may help identify potential targets for drug development.

The Effect of Lactobacillus crispatus and Lactobacillus rhamnosusCulture Supernatants on Expression of Autophagy Genes and HPV E6 and E7 Oncogenes in The HeLa Cell Line.

The aim of this study was to clarify the mechanism by which lactobacilli exert their cytotoxic effects on cervical cancer cells. In addition, we aimed to evalu- ate the effect of lactobacilli on the expression of human papilloma virus (HPV) onco- genes. In this experimental study, using quantitative real-time polymer- ase chain reaction (PCR), we analyzed the expression of CASP3 and three autophagy genes [ATG14, BECN1 and alpha 2 catalytic subunit of AMPK (PRKAA2)] along with HPV18 E6 and E7 genes in HeLa cells before and after treatment with Lactobacillus crispatus and Lactobacillus rhamnosus culture supernatants. The expression of CASP3 and autophagy genes in HeLa cells was de- creased after treatment with lactobacilli culture supernatants. However, this de- crease was not significant for PRKAA2 when compared with controls. In addition, expression of HPV E6 was significantly decreased after treatment with lactobacilli culture supernatants. Lactobacilli culture supernatants can decrease expression of ATG14 and BECN1 as well as the HPV E6 oncogene. It has been demonstrated that the main changes occurring during cervical carcinogenesis in cell machinery can be reversed by suppression of HPV oncogenes. Therefore, downregulation of HPV E6 by lacto- bacilli may have therapeutic potential for cervical cancer. As the role of autophagy in cancer is complicated, further work is required to clarify the link between downregula- tion of autophagy genes and antiproliferative effects exerted by lactobacilli.

Computational prediction of linear B-cell epitopes in the E5 oncoprotein of the human papillomavirus type 16 using several bioinformatics tools

Human papillomavirus (HPV), one of the most common sexually transmitted infections worldwide, affects around 300 million new individuals each year. The HPV E5 gen appear to have coevolved with the major HPV oncogenes E6 and E7, and their presence in the viral genome correlates with risk of cancer. HPV-16 E5 is an oncoprotein with many functions during HPV-16 infection. The development of computational methods for epitope finding becomes an alternative to the wet experimental techniques, in order to save time and cost. In this work the bioinformatic tools: Predict Protein, BCPREDS (AAP, BCpreds and FBCPred), ABCpred, BepiPred, SVMTriP, LBtope, IEDB and LEPS were used in order to elucidate B-cell epitopes on HPV-16 E5. The HPV-16 E5 secondary structure was used to mapping the B-cell epitopes obtained in this study. A total of 202 B-cell epitopes and 44 B-cell epitopes with tumor activity were obtained with all together bioinformatics tools. Differences in ratio of these epitopes with the three α-helices of the secondary structure determined by Predict Protein were observed. The predicted epitopes in this study could facilitate the design of future therapeutic vaccines and the understanding of the immunological mechanisms of HPV-16.

Loss of E2F1 Extends Survival and Accelerates Oral Tumor Growth in HPV-Positive Mice.

The Human Papillomavirus (HPV) is associated with several human cancers, including head and neck squamous cell carcinomas (HNSCCs). HPV expresses the viral oncogene E7 that binds to the retinoblastoma protein (RB1) in order to activate the E2F pathway. RB1 can mediate contradictory pathways—cell growth and cell death via E2F family members. Here, we assessed the extent to which E2F1 mediates lethality of HPV oncogenes. Ubiquitous expression of the HPV oncogenes E6 and E7 caused lethality in mice that was associated with focal necrosis in hepatocytes and pancreatic tissues. Furthermore, all organs expressing HPV oncogenes displayed up-regulation of several E2F1 target genes. The E2F1 pathway mediated lethality in HPV-positive mice because deletion of E2F1 increased survival of mice ubiquitously expressing HPV oncogenes. E2F1 similarly functioned as a tumor suppressor in HPV-positive oral tumors as tumors grew faster with homozygous loss of E2F1 compared to tumors with heterozygous loss of E2F1. Re-expression of E2F1 caused decreased clonogenicity in HPV-positive cancer cells. Our results indicate that HPV oncogenes activated the E2F1 pathway to cause lethality in normal mice and to suppress oral tumor growth. These results suggest that selective modulation of the E2F1 pathway, which is activated in HPV tumors, may facilitate tumor regression.

E3 ligase EDD1/UBR5 is utilized by the HPV E6 oncogene to destabilize tumor suppressor TIP60.

Tat-interacting protein of 60 kDa (TIP60) is an essential lysine acetyltransferase implicated in transcription, DNA damage response and apoptosis. TIP60 protein expression is reduced in cancers. In cervical cancers, human papillomavirus (HPV) E6 oncogene targets cellular p53, Bak and some of the PDZ domain-containing proteins for proteasome-mediated degradation through E6AP ligase. Recently, E6 oncogene from high-risk and low-risk categories was also shown to target TIP60. However, the molecular mechanisms and whether destabilization of TIP60 contributes to HPV E6-mediated transformation remain unanswered. Our proteomic analyses revealed EDD1 (E3 identified by differential display), an E3 ligase generally overexpressed in cancers as a novel interacting partner of TIP60. By investigating protein turnover and ubiquitination assays, we show that EDD1 negatively regulates TIP60's stability through the proteasome pathway. Strikingly, HPV E6 uses this function of EDD1 to destabilize TIP60. Colony-formation assays and soft agar assays show that gain of function of TIP60 or depletion of EDD1 in HPV-positive cervical cancer cells significantly inhibits cell growth in vitro. This phenotype is strongly supported by the in-vivo studies where re-activation of TIP60 in cervical cancer cells dramatically reduces tumor formation. In summary, we have discovered a novel ligase through which E6 destabilizes TIP60. Currently, in the absence of an effective therapeutic vaccine for malignant cervical cancers, cervical cancer still remains to be a major disease burden. Hence, our studies implying a distinct tumor suppressor role for TIP60 in cervical cancers show that reactivation of TIP60 could be of therapeutic value.

Abstract 813: Human papillomavirus 16 oncoprotein E6 upregulates c-Met partially through p53 in squamous cell carcinoma of the head and neck

Abstract Background: Human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) carries a distinct clinical behavior. The c-Met oncogene is an important driver for tumorigenesis, however, its relationship with HPV oncoproteins remains unclear. The present study aims to uncover the role of HPV in regulation of c-Met in OPSCC. Methods: We first knocked down the HPV oncogene E6 by siRNA to check alteration of c-Met expression through western blot and qRT-PCR in several HPV-positive HNSCC cell lines and the cervical cancer cell line CaSki. Next, we tested if E6 regulated c-Met expression is p53 dependent. Simultaneous knockdown of p53 and E6 was compared to E6 knockdown alone for the impact of p53 on c-Met expression using western blot analysis. In addition, the effects of c-Met inhibition by both siRNA and a c-Met specific inhibitor SU11274 on cell proliferation, migration, and colony formation were tested by sulforhodamine B colorimetric assay (SRB), wound healing assay, and colony formation assay, respectively, in HPV-positive cancer cell lines. Using retrospectively collected tissue specimens from 78 patients with OPSCC (N = 58 for HPV-positive vs. N = 20 for HPV-negative), we stained for c-Met and p53 by immunohistochemistry and correlated their expression with HPV status determined by HPV DNA in situ hybridization as well as other clinical characteristics. Results: E6 knockdown significantly decreased c-Met protein and mRNA expression in HPV-associated HNSCC and CaSki cell lines. E6 regulated c-Met expression was partially blocked by the elimination of p53. c-Met inhibition significantly decreased cell proliferation, migration, and colony formation. In patient samples, multivariate analysis revealed a significant association of c-Met expression with HPV status (positive vs. negative, OR = 4.11, 95%CI: 1.16-14.55, P = 0.028) as well as tumor stage (T1/2 vs. T3/4, OR = 0.27, 95%CI: 0.08-0.93, P = 0.039). In T3/T4 stage patients (N = 21), c-Met expression was significantly higher in HPV-positive patients and inversely related with p53 levels, supporting an axis of E6-p53-c-Met regulation. Conclusion: Our results show that c-Met expression is upregulated by HPV E6, which is partially mediated by p53. The data suggest that targeting c-Met may serve as a novel approach for treating HPV-associated OPSCC. (This study was supported by grants from Small Business Innovation Research (SBIR) Program (HHSN261201200097C), National Institutes of Health (R33 CA161873), and National Cancer Institute (NCI P50 CA 128613, Head and Neck SPORE). Citation Format: Guoqing Qian, Dongsheng Wang, Kelly R. Magliocca, Praveen Duggal, Sreenivas Nannapaneni, Sungjin Kim, Zhengjia Chen, Dong M. Shin, Nabil F. Saba, Zhuo G. Chen. Human papillomavirus 16 oncoprotein E6 upregulates c-Met partially through p53 in squamous cell carcinoma of the head and neck. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 813. doi:10.1158/1538-7445.AM2015-813

Codon Optimization of the Human Papillomavirus E7 Oncogene Induces a CD8+ T Cell Response to a Cryptic Epitope Not Harbored by Wild-Type E7

Codon optimization of nucleotide sequences is a widely used method to achieve high levels of transgene expression for basic and clinical research. Until now, immunological side effects have not been described. To trigger T cell responses against human papillomavirus, we incubated T cells with dendritic cells that were pulsed with RNA encoding the codon-optimized E7 oncogene. All T cell receptors isolated from responding T cell clones recognized target cells expressing the codon-optimized E7 gene but not the wild type E7 sequence. Epitope mapping revealed recognition of a cryptic epitope from the +3 alternative reading frame of codon-optimized E7, which is not encoded by the wild type E7 sequence. The introduction of a stop codon into the +3 alternative reading frame protected the transgene product from recognition by T cell receptor gene-modified T cells. This is the first experimental study demonstrating that codon optimization can render a transgene artificially immunogenic through generation of a dominant cryptic epitope. This finding may be of great importance for the clinical field of gene therapy to avoid rejection of gene-corrected cells and for the design of DNA- and RNA-based vaccines, where codon optimization may artificially add a strong immunogenic component to the vaccine.

Human Papilloma Virus (HPV) Infection and Non-Cervical Oncogenic Disease States

Human papillomavirus (HPV) infection is causative for cervical cancer and has been implicated in cancers at other sites. We review the English language literature in regard to the epidemiology of HPV infection as a risk for non-cervical cancer with a focus on the molecular evidence to support HPV having an etiologic role at each anatomic site. HPV DNA is detected in and/or serology provides evidence that HPV is associated with 35-50% of penile cancers, 80-95% of anal cancers, and ~35% of oropharyngeal cancers. HPV has also been implicated for cancer of the larynx, esophagus, lung, and urinary bladder with varying levels of linkage. Molecular studies at the respective anatomic sites provide evidence of HPV integration, E6 and E7 oncogene expression coupled with tumor suppressor down-regulation consistent with a role in the pathogenesis of tumor formation. HPV-associated cancer may represent a distinct disease entity relative to non HPV-associated cancers based upon natural history and outcome studies. Thus, the disease burden of HPV associated non-cervical cancers may be significant and justifies a comprehensive investigation of the utility of global prophylactic vaccination strategies.

Bioluminescent Imaging of HPV-Positive Oral Tumor Growth and Its Response to Image-Guided Radiotherapy

The treatment paradigms for head and neck squamous cell cancer (HNSCC) are changing due to the emergence of human papillomavirus (HPV)-associated tumors possessing distinct molecular profiles and responses to therapy. Although patients with HNSCCs are often treated with radiotherapy, preclinical models are limited by the ability to deliver precise radiation to orthotopic tumors and to monitor treatment responses accordingly. To better model this clinical scenario, we developed a novel autochthonous HPV-positive oral tumor model to track responses to small molecules and image-guided radiation. We used a tamoxifen-regulated Cre recombinase system to conditionally express the HPV oncogenes E6 and E7 as well as a luciferase reporter (iHPV-Luc) in the epithelial cells of transgenic mice. In the presence of activated Cre recombinase, luciferase activity, and by proxy, HPV oncogenes were induced to 11-fold higher levels. In triple transgenic mice containing the iHPV-Luc, K14-CreER(tam), and LSL-Kras transgenes, tamoxifen treatment resulted in oral tumor development with increased bioluminescent activity within 6 days that reached a maximum of 74.8-fold higher bioluminescence compared with uninduced mice. Oral tumors expressed p16 and MCM7, two biomarkers associated with HPV-positive tumors. After treatment with rapamycin or image-guided radiotherapy, tumors regressed and possessed decreased bioluminescence. Thus, this novel system enables us to rapidly visualize HPV-positive tumor growth to model existing and new interventions using clinically relevant drugs and radiotherapy techniques.

Genome-wide analysis of HPV integration in human cancers reveals recurrent, focal genomic instability

Genomic instability is a hallmark of human cancers, including the 5% caused by human papillomavirus (HPV). Here we report a striking association between HPV integration and adjacent host genomic structural variation in human cancer cell lines and primary tumors. Whole-genome sequencing revealed HPV integrants flanking and bridging extensive host genomic amplifications and rearrangements, including deletions, inversions, and chromosomal translocations. We present a model of “looping” by which HPV integrant-mediated DNA replication and recombination may result in viral–host DNA concatemers, frequently disrupting genes involved in oncogenesis and amplifying HPV oncogenes E6 and E7. Our high-resolution results shed new light on a catastrophic process, distinct from chromothripsis and other mutational processes, by which HPV directly promotes genomic instability.

Autocorrelation method for fractal analysis in nonrectangular image domains

We report an autocorrelation-based approach that accurately measures fractal organization within arbitrarily shaped (nonrectangular) regions of interest of gray-scale images. It extends fractal analysis beyond what is possible using fast Fourier transforms and improves on a previous autocorrelation algorithm. We illustrate its use in detecting subtle changes in mitochondrial organization within murine fibroblasts expressing the human papillomavirus E7 oncogene.

HPV16 E5 peptide vaccine in treatment of cervical cancer in vitro and in vivo

Human papillomavirus (HPV)-induced cervical cancer is the second most common cancer among women worldwide. Despite the encouraging development of the preventive vaccine for HPV, a vaccine for both prevention and therapy or pre-cancerous lesions remains in high priority. Thus far, most of the HPV therapeutic vaccines are focused on HPV E6 and E7 oncogene. However these vaccines could not completely eradicate the lesions. Recently, HPV E5, which is considered as an oncogene, is getting more and more attention. In this study, we predicted the epitopes of HPV16 E5 by bioinformatics as candidate peptide, then, evaluated the efficacy and chose an effective one to do the further test. To evaluate the effect of vaccine, rTC-1 (TC-1 cells infected by rAAV-HPV16E5) served as cell tumor model and rTC-1 loading mice as an ectopic tumor model. We prepared vaccine by muscle injection. The vaccine effects were determined by evaluating the function of tumor-specific T cells by cell proliferation assay and ELISPOT, calculating the tumor volume in mice and estimating the survival time of mice. Our in vitro and in vivo studies revealed that injection of E5 peptide+CpG resulted in strong cell-mediated immunity (CMI) and protected mice from tumor growth, meanwhile, prolonged the survival time after tumor cell loading. This study provides new insights into HPV16 E5 as a possible target on the therapeutic strategies about cervical cancer.

Identification of miRNAs dysregulated in human foreskin keratinocytes (HFKs) expressing the human papillomavirus (HPV) Type 16 E6 and E7 oncoproteins.

Human papillomaviruses (HPVs) are associated with the pathogenesis of a variety of human cancers, including cervical and oropharyngeal cancers. The HPV E6 and E7 oncogenes are usually expressed to high levels in these cancers. Previous studies have shown dysregulation of cellular microRNAs (miRNAs) in HPV-positive cell lines and cancer tissues and recent studies have identified a few miRNAs whose levels are altered in the presence of the viral E6 and E7 proteins. In order to identify all the cellular miRNAs whose expression may be affected by these oncoproteins, we carried out microarray analysis using human foreskin keratinocytes (HFKs) expressing either or both of these two proteins. These studies showed that 90 and 60 miRNAs were dysregulated in the presence of the E6 or the E7 protein, respectively. Of these, 43 miRNAs were similarly affected in HFK-E6 and/or HFK-E7 when compared to control cells. The joint expression of E6 and E7 proteins in HFKs caused changes in the levels of 64 miRNAs, of which 24 were similarly affected in HFK-E6 and/or HFK-E7 cells relative to controls. The microarray experiments were validated by quantitative real-time RT-PCR analysis of several differentially expressed miRNAs. Several miRNAs dysregulated by the E6 and/or E7 proteins are known to be altered in a variety of human cancers. Furthermore, previously known cellular targets of these miRNAs are involved in processes such as cell cycle regulation, apoptosis, cell-cell adhesion, cell mobility and proliferation, and alterations in their levels may contribute to HPV-associated carcinogenesis. Taken together, the results of our studies suggest that high risk HPV E6 and E7 proteins share the ability to regulate a subset of cellular miRNAs.

Crucial Role of TSC-22 in Preventing the Proteasomal Degradation of p53 in Cervical Cancer

The p53 tumor suppressor function can be compromised in many tumors by the cellular antagonist HDM2 and human papillomavirus oncogene E6 that induce p53 degradation. Restoration of p53 activity has strong therapeutic potential. Here, we identified TSC-22 as a novel p53-interacting protein and show its novel function as a positive regulator of p53. We found that TSC-22 level was significantly down-regulated in cervical cancer tissues. Moreover, over-expression of TSC-22 was sufficient to inhibit cell proliferation, promote cellular apoptosis in cervical cancer cells and suppress growth of xenograft tumors in mice. Expression of also TSC-22 enhanced the protein level of p53 by protecting it from poly-ubiquitination. When bound to the motif between amino acids 100 and 200 of p53, TSC-22 inhibited the HDM2- and E6-mediated p53 poly-ubiquitination and degradation. Consequently, ectopic over-expression of TSC-22 activated the function of p53, followed by increased expression of p21Waf1/Cip1 and PUMA in human cervical cancer cell lines. Interestingly, TSC-22 did not affect the interaction between p53 and HDM2. Knock-down of TSC-22 by small interfering RNA clearly enhanced the poly-ubiquitination of p53, leading to the degradation of p53. These results suggest that TSC-22 acts as a tumor suppressor by safeguarding p53 from poly-ubiquitination mediated-degradation.

New Developments in Therapeutic HPV Vaccines

Human papillomavirus (HPV) infection is the central causal factor in cervical cancer. For years efforts were undertaken to control HPV-associated disease by the development of HPV vaccines. While prophylactic HPV vaccination represents a major public health breakthrough, it is limited to new infection by certain HPV types and does not have therapeutic effects or prevent progression of pre-existing HPV infections to malignancy. Thus, there is an urgent need for therapeutic HPV vaccines. Therapeutic vaccines aim to induce cytotoxic T cells, facilitating clearance of HPV high-grade lesions and cancers. HPV E6 and E7 oncogenes represent ideal antigens for therapeutic HPV vaccination because of their constitutive expression in HPV-containing carcinomas and their critical role in the induction and maintenance of HPV-associated disease. This review discusses the most recent advances in HPV therapeutic vaccines and summarizes effects of new basic immunology findings and vaccine delivery technologies.

Abstract 2882: Therapeutic effects of ormeloxifene on cervical cancer

Abstract Background: Cervical cancer is one of the most common and deadly cancers among women worldwide and is strongly associated with persistent Human Papillomavirus (HPV) infection. HPV E6/E7 oncoproteins are well known to interfere with p53 and retinoblastoma (Rb) proteins and drive the development of cervical cancer. While screening for cervical cancer can reduce the incidence and mortality, treatment of advanced stage cervical cancer is difficult and often unsuccessful. Therefore, there is an urgent need for the development of additional treatment modalities. Ormeloxifene is a non-hormonal anti-estrogen oral contraceptive for human use and it effectively suppresses the highly proliferative decidual cells in the endometrium to inhibit egg implantation. Considering its strong anti-proliferative effect, we hypothesized that ormeloxifene may inhibit the growth of cervical cancer cells and may suppress the expression of HPV oncoproteins E6/E7. Methods: The effect of ormeloxifene on the proliferation of various cervical cancer cell lines (Caski, SiHa, C33A, and HT3) was determined by MTS and colony formation assay. Annexin V/7AAD and propidium iodide (PI) staining was analyzed by flow cytometry to determine ormeloxifene's effect on apoptosis and cell cycle inhibition, respectively. The expression of apoptotic proteins such as poly (ADP-ribose) polymerase (PARP), Caspase 3 and Caspase 9 was determined by immunoblotting. The potential of ormeloxifene to repress the expression of HPV E6/E7 oncogenes was determined by quantitative RT-PCR and immunoblotting analyses. Further, the efficacy of ormeloxifene to restore tumor suppressor proteins, such as p53 and Rb, was also determined by immunoblotting. Results: In all 4 cell lines, ormeloxifene effectively inhibited cervical cancer cell growth. Ormeloxifene treatment induced apoptosis in cervical cancer cells as determined by staining for Annexin V/7AAD and immunoblotting for cleaved PARP, Caspase 3, and Caspase 9. PI staining also clearly revealed that ormeloxifene treatment arrests Caski cells in the G0-G1 phase. Additionally, ormeloxifene treatment caused a marked decrease in the levels of HPV E6 and E7 oncogenes and restored the levels of p53 and Rb proteins in Caski cells. Conclusion: Our findings show that ormeloxifene significantly inhibits cervical cancer cell growth and down-regulates HPV E6/E7 oncogenes, therefore; ormeloxifene may be novel chemo-preventive and treatment method for the management of cervical cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2882. doi:1538-7445.AM2012-2882

MicroRNAs and senescence

MicroRNAs and senescence