Oscar Peralta-Zaragoza

MicroRNAs transported by exosomes in body fluids as mediators of intercellular communication in cancer

Cancer-cell communication is an important and complex process, achieved through a diversity of mechanisms that allows tumor cells to mold and influence their environment. In recent years, evidence has accumulated indicating that cells communicate via the release and delivery of microRNAs (miRNAs) packed into tumor-released (TR) exosomes. Understanding the role and mode of action of miRNAs from TR exosomes is of paramount importance in the field of cancer biomarker discovery and for the development of new biomedical applications for cancer therapeutics. In this review, we focus on miRNAs secreted via TR exosomes, which by acting in a paracrine or endocrine manner, facilitate a diversity of signaling mechanisms between cancer cells. We address their contribution as signaling molecules, to the establishment, maintenance, and enhancement of the tumor microenvironment and the metastatic niche in cancer. Finally, we address the potential role of these molecules as biomarkers in cancer diagnosis and prognosis and their impact as a biomedical tool in cancer therapeutics.

Targeted treatments for cervical cancer: a review.

Cervical cancer is the second most common cause of cancer death in women worldwide and the development of new diagnosis, prognostic, and treatment strategies merits special attention. Although surgery and chemoradiotherapy can cure 80%–95% of women with early stage cancer, the recurrent and metastatic disease remains a major cause of cancer death. Many efforts have been made to design new drugs and develop gene therapies to treat cervical cancer. In recent decades, research on treatment strategies has proposed several options, including the role of HPV E6 and E7 oncogenes, which are retained and expressed in most cervical cancers and whose respective oncoproteins are critical to the induction and maintenance of the malignant phenotype. Other efforts have been focused on antitumor immunotherapy strategies. It is known that during the development of cervical cancer, a cascade of abnormal events is induced, including disruption of cellular cycle control, perturbation of antitumor immune response, alteration of gene expression, and deregulation of microRNA expression. Thus, in this review article we discuss potential targets for the treatment of cervical cancer associated with HPV infection, with special attention to immunotherapy approaches, clinical trials, siRNA molecules, and their implications as gene therapy strategies against cervical cancer development.

Human papilloma virus, DNA methylation and microRNA expression in cervical cancer (Review).

Cancer is a complex disease caused by genetic and epigenetic abnormalities that affect gene expression. The progression from precursor lesions to invasive cervical cancer is influenced by persistent human papilloma virus (HPV) infection, which induces changes in the host genome and epigenome. Epigenetic alterations, such as aberrant miRNA expression and changes in DNA methylation status, favor the expression of oncogenes and the silencing of tumor-suppressor genes. Given that some miRNA genes can be regulated through epigenetic mechanisms, it has been proposed that alterations in the methylation status of miRNA promoters could be the driving mechanism behind their aberrant expression in cervical cancer. For these reasons, we assessed the relationship among HPV infection, cellular DNA methylation and miRNA expression. We conclude that alterations in the methylation status of protein-coding genes and various miRNA genes are influenced by HPV infection, the viral genotype, the physical state of the viral DNA, and viral oncogenic risk. Furthermore, HPV induces deregulation of miRNA expression, particularly at loci near fragile sites. This deregulation occurs through the E6 and E7 proteins, which target miRNA transcription factors such as p53.

Role of IL-10 and TGF-β1 in local immunosuppression in HPV-associated cervical neoplasia.

Cervical cancer is a worldwide disease that constitutes a significant public health problem, especially in developing countries, not only due to its high incidence but also because the most affected population comprises women who belong to marginalized socio-economic classes. Clinical and molecular research has identified immunological impairment in squamous intraepithelial cervical lesions and cervical cancer patients. Human Papillomavirus (HPV) has several mechanisms for avoiding the immune system: it down-regulates the expression of interferon and upregulates interleukin (IL)-10 and transforming growth factor (TGF)-β1 to produce a local immunosuppressive environment, which, along with altered tumor surface antigens, forms an immunosuppressive network that inhibits the antitumor immune response. In this review we analyzed the available data on several deregulated cellular immune functions in patients with NIC I, NIC II and NIC III and cervical cancer. The effects of immunosuppressive cytokines on innate immune response, T-cell activation and cellular factors that promote tumor cell proliferation in cervical cancer patients are summarized. We discuss the functional consequences of HPV E2, E6, and E7 protein interactions with IL-10 and TGF-β1 promoters in the induction of these cytokines and postulate its effect on the cellular immune response in squamous intraepithelial cervical lesions and cervical cancer patients. This review provides a comprehensive picture of the immunological functions of IL-10 and TGF-β1 in response to HPV in humans.

MicroRNAs in cervical cancer: evidences for a miRNA profile deregulated by HPV and its impact on radio-resistance.

Cervical carcinoma (CC) is one of the most common cancers and a leading cause of mortality in women worldwide. Epidemiologic and experimental data have clearly demonstrated a causal role of high-risk Human Papillomavirus (HR-HPV) types in CC initiation and progression, affecting the cellular processes by targeting and inactivating p53 and pRB host proteins. HR-HPV E5, E6 and E7 oncoproteins have the ability to deregulate several cellular processes, mostly apoptosis, cell cycle control, migration, immune evasion, and induction of genetic instability, which promote the accumulation of mutations and aneuploidy. In this scenario, genomic profiles have shown that aberrant expression of cellular oncogenic and tumor suppressive miRNAs have an important role in CC carcinogenesis. It has been stated that HPV infection and E6/E7 expression are essential but not sufficient to lead to CC development; hence other genetic and epigenetic factors have to be involved in this complex disease. Recent evidence suggests an important level of interaction among E6/E7 viral proteins and cellular miRNA, and other noncoding RNAs. The aim of the current review is to analyze recent data that mainly describe the interaction between HR-HPV established infections and specific cellular miRNAs; moreover, to understand how those interactions could affect radio-therapeutic response in tumor cells.

Relevance of miR-21 in regulation of tumor suppressor gene PTEN in human cervical cancer cells

BackgroundExpression of the microRNA miR-21 has been found to be altered in almost all types of cancers and it has been classified as an oncogenic microRNA or oncomir. Due to the critical functions of its target proteins in various signaling pathways, miR-21 is an attractive target for genetic and pharmacological modulation in various cancers. Cervical cancer is the second most common cause of death from cancer in women worldwide and persistent HPV infection is the main etiologic agent. This malignancy merits special attention for the development of new treatment strategies. In the present study we analyze the role of miR-21 in cervical cancer cells.MethodsTo identify the downstream cellular target genes of upstream miR-21, we silenced endogenous miR-21 expression in a cervical intraepithelial neoplasia-derived cell lines using siRNAs. The effect of miR-21 on gene expression was assessed in cervical cancer cells transfected with the siRNA expression plasmid pSIMIR21. We identified the tumor suppressor gene PTEN as a target of miR-21 and determined the mechanism of its regulation throughout reporter construct plasmids. Using this model, we analyzed the expression of miR-21 and PTEN as well as functional effects such as autophagy and apoptosis induction.ResultsIn SiHa cells, there was an inverse correlation between miR-21 expression and PTEN mRNA level as well as PTEN protein expression in cervical cancer cells. Transfection with the pSIMIR21 plasmid increased luciferase reporter activity in construct plasmids containing the PTEN-3′-UTR microRNA response elements MRE21-1 and MRE21-2. The role of miR-21 in cell proliferation was also analyzed in SiHa and HeLa cells transfected with the pSIMIR21 plasmid, and tumor cells exhibited markedly reduced cell proliferation along with autophagy and apoptosis induction.ConclusionsWe conclude that miR-21 post-transcriptionally down-regulates the expression of PTEN to promote cell proliferation and cervical cancer cell survival. Therefore, it may be a potential therapeutic target in gene therapy for cervical cancer.

Urinary microRNA-based signature improves accuracy of detection of clinically relevant prostate cancer within the prostate-specific antigen grey zone

At present, prostate-specific antigen (PSA) is used as a clinical biomarker for prostate cancer (PCa) diagnosis; however, a large number of patients with benign prostate hyperplasia (BPH) with PSA levels in the ʻgray areaʼ (4–10 ng/ml) are currently subjected to unnecessary biopsy due to overdiagnosis. Certain microRNAs (miRs) have been proven to be useful biomarkers, several of which are detectable in bodily fluids. The present study identified and validated a urinary miR-based signature to enhance the specificity of PCa diagnosis and to reduce the number of patients with benign conditions undergoing biopsy. Seventy-three urine samples from Mexican patients with diagnosis of PCa with a Gleason score ≥7 and 70 patients diagnosed with BPH were collected after digital rectal examination (DRE) of the prostate. miR expression profiles were determined using TaqMan Low Density Array experiments, and normalized Ct values for the miRs were compared between PCa and BPH groups. Receiver operating characteristic (ROC) curve analysis was performed to evaluate whether miR detection in urine is suitable for distinguishing patients with PCa from those with BPH. The identified miR-100/200b signature was significantly correlated with PCa. Using a multivariable logistic regression approach, a base model including the clinical variables age, prostate-specific antigen (PSA), the percentage of free PSA and DRE was generated, and a second base model additionally contained the miR-100/200b signature. ROC analysis demonstrated that the combined model significantly outperformed the capacity of PSA (P<0.001) and the base model (P=0.01) to discriminate between PCa and BPH patients. In terms of evaluation of the sub-group of patients in the gray zone of PSA levels, the performance of the combined model for predicting PCa cases was significantly superior to PSA level determination (P<0.001) and the base model (P=0.009). In addition, decision curve analysis demonstrated that the use of the combined model increased the clinical benefit for patients and produced a substantial reduction in unnecessary biopsies across a range of reasonable threshold probabilities (10–50%). Detection of the urinary miR signature identified in the present study as part of clinical diagnostic procedures will enhance the accuracy of PCa diagnosis and provide a clinical benefit for patients with BPH by sparing them from undergoing invasive biopsy. To the best of our knowledge, the present study was the first to describe the profiling of urinary miR100 and miR-200b levels for the clinical diagnosis of PCa.

The EPIYA-ABCC motif pattern in CagA of Helicobacter pylori is associated with peptic ulcer and gastric cancer in Mexican population

BackgroundHelicobacter pylori chronic infection is associated with chronic gastritis, peptic ulcer, and gastric cancer. Cytotoxin-associated gene A (cagA)-positive H. pylori strains increase the risk of gastric pathology. The carcinogenic potential of CagA is linked to its polymorphic EPIYA motif variants. The goals of this study were to investigate the frequency of cagA-positive Helicobacter pylori in Mexican patients with gastric pathologies and to assess the association of cagA EPIYA motif patterns with peptic ulcer and gastric cancer.MethodsA total of 499 patients were studied; of these, 402 had chronic gastritis, 77 had peptic ulcer, and 20 had gastric cancer. H. pylori DNA, cagA, and the EPIYA motifs were detected in total DNA from gastric biopsies by PCR. The type and number of EPIYA segments were determined by the electrophoretic patterns. To confirm the PCR results, 20 amplicons of the cagA 3′ variable region were sequenced, and analyzed in silico, and the amino acid sequence was predicted with MEGA software, version 5. The odds ratio (OR) was calculated to determine the associations between the EPIYA motif type and gastric pathology and between the number of EPIYA-C segments and peptic ulcers and gastric cancer.ResultsH. pylori DNA was found in 287 (57.5%) of the 499 patients, and 214 (74%) of these patients were cagA-positive. The frequency of cagA-positive H. pylori was 74.6% (164/220) in chronic gastritis patients, 73.6% (39/53) in peptic ulcer patients, and 78.6% (11/14) in gastric cancer patients. The EPIYA-ABC pattern was more frequently observed in chronic gastritis patients (79.3%, 130/164), while the EPIYA-ABCC sequence was more frequently observed in peptic ulcer (64.1%, 25/39) and gastric cancer patients (54.5%, 6/11). However, the risks of peptic ulcer (OR = 7.0, 95% CI = 3.3–15.1; p < 0.001) and gastric cancer (OR = 5.9, 95% CI = 1.5–22.1) were significantly increased in individuals who harbored the EPIYA-ABCC cagA gene pattern.ConclusionscagA-positive H. pylori is highly prevalent in southern Mexico, and all CagA variants were of the western type. The cagA alleles that code for EPIYA-ABCC motif patterns are associated with peptic ulcers and gastric cancer.

Terapia génica con citocinas contra cáncer cervicouterino

Bermudez-Morales VH, Peralta-Zaragoza O, Madrid-Marina V. Gene therapy with cytokines against cervical cancer. Salud Publica Mex 2005;47:458-468. Abstract Gene therapy is an excellent alternative for treatment of many diseases. Capacity to manipulate the DNA has allowed direct the gene therapy to correct the function of an altered gene, to increase the expression of a gene and to favour the activation of the immune response. This way, it can intend the use of the DNA like medication able to control, to correct or to cure many diseases. Gene therapy against cancer has an enormous potential, and actually the use of the DNA has increased to control diverse cancer in animal models, with very encoura- ging results that have allowed its applications in experimental protocols in human. This work concentrates a review of the foundations of the gene therapy and its application on cervical cancer, from the point of view of the alterations of the immune system focused on the tumour micro-environment, and the use of the cytokines as immunomodulators.

HPV-Based Screening, Triage, Treatment, and Followup Strategies in the Management of Cervical Intraepithelial Neoplasia.

Cervical cancer is the second most common cause of death from cancer in women worldwide, and the development of new diagnostic, prognostic, and treatment strategies merits special attention. Many efforts have been made to design new drugs and develop immunotherapy and gene therapy strategies to treat cervical cancer. HPV genotyping has potentially valuable applications in triage of low-grade abnormal cervical cytology, assessment of prognosis and followup of cervical intraepithelial neoplasia, and in treatment strategies for invasive cervical cancer. It is known that during the development of cervical cancer associated with HPV infection, a cascade of abnormal events is induced, including disruption of cellular cycle control, alteration of gene expression, and deregulation of microRNA expression. Thus, the identification and subsequent functional evaluation of host proteins associated with HPV E6 and E7 oncoproteins may provide useful information in understanding cervical carcinogenesis, identifying cervical cancer molecular markers, and developing specific targeting strategies against tumor cells. Therefore, in this paper, we discuss the main diagnostic methods, management strategies, and followup of HPV-associated cervical lesions and review clinical trials applying gene therapy strategies against the development of cervical cancer.