Leticia Rocha-Zavaleta

Human papillomavirus infection and cervical ectopy

Objectives: To investigate the prevalence of human papillomavirus (HPV), and HPV type 16 (HPV16) infection in cervical ectopy, and the presence of anti‐HPV16 secretory IgA (sIgA) antibodies. Methods: DNA from patients with cervical ectopy (n=218), HPV‐associated lesions (n=111), and controls without evidence of cervical ectopy or HPV infection (n=93) were analyzed by PCR for the presence of HPV and HPV16. The presence of mucosal sIgA antibodies against HPV16 capsid antigens (VLP) was assayed in cervical mucus by ELISA. Results: Prevalence of HPV DNA was higher in cervical ectopy than in controls (P=0.04; OR=2.06; 95% CI 0.99–4.33). HPV16 was 6.3 times more prevalent in cervical ectopy than in controls. Anti‐HPV16 sIgA were detected more frequently in cervical ectopy patients than in controls (P=0.0004). Conclusions: Cervical ectopy correlates with HPV infection. HPV16 is highly prevalent in cervical ectopy. sIgA antibodies against HPV16 capsids are generated in patients with cervical ectopy.

The Role of Signaling Pathways in Cervical Cancer and Molecular Therapeutic Targets

Cervical cancer is a public health issue in developing countries. Although the Pap smear and colposcopy remain the major strategies for detection, most cases are diagnosed in the late stages. Therefore, a major concern has been to develop early diagnostic approaches and more effective treatments. Molecular pathways that participate in cervical malignant transformation have emerged as promising directed therapeutic targets. In this review, we explore some of the major pathways implicated in cervical cancer development, including RAF/MEK/ERK, phosphatidylinositol-3 kinase (PI3K/AKT), Wnt/b-catenin, apoptosis and coupled membrane receptor signaling. We focus on the role of these pathways in cervical carcinogenesis, their alterations and the consequences of these abnormalities. In addition, the most recent preclinical and clinical data on the rationally designed target-based agents that are currently being tested against elements of these pathways are reviewed.

Autocrine/paracrine erythropoietin signalling promotes JAK/STAT-dependent proliferation of human cervical cancer cells.

Erythropoietin (Epo) regulates erythropoiesis by binding to its receptor (EpoR) and promoting cell proliferation, differentiation and inhibition of apoptosis. Epo is widely used to treat cervical cancer‐related anaemia. However, there are data suggesting that administration of Epo is associated with an increment in recurrence rate, and decreased disease‐free and overall survival. In the present study, we investigated the expression of Epo and EpoR on cervical cancer cell lines. We observed that both EpoR and extracellular Epo are constitutively expressed in cervical cancer cells. Inhibition of either Epo or EpoR expression with siRNA attenuated cell proliferation, whereas addition of exogenous Epo led to a significant increase in cell growth, both in vitro and in vivo. Epo‐induced proliferation was associated with the activation of JAK2, JAK3, STAT3 and STAT5 but not JAK1 and STAT1. Our results are consistent with the existence of a functional, endogenous Epo/EpoR system in cervical cancer with the capacity to activate the transduction of signals resulting in an increased proliferation potential.

Hypoxia inducible factor-1α induces chemoresistance phenotype in non-Hodgkin lymphoma cell line via up-regulation of Bcl-xL

Abstract Non-Hodgkin lymphoma (NHL) is one of the most common cancers in childhood. The development of chemoresistance in tumor cells is one of the principal causes of treatment failure. This resistance has been associated with different mechanisms, one being the overexpression of anti-apoptotic proteins such as Bcl-xL. It has been shown that this protein is regulated by the transcription factor hypoxia inducible factor-1α (HIF-1α), which is overexpressed in several tumors including NHL, and the overexpression of both proteins may result in resistance to chemotherapy. We investigated the role of HIF-1α in resistance to chemotherapy via the induction of Bcl-xL expression in NHL cell lines, using a pharmacological modulation of HIF-1α. Our data showed that treating Ramos cells with ethyl 3,4-dihydroxybenzoate, an inhibitor of prolyl hydroxylase, induces accumulation of HIF-1α and this correlates with an increase of Bcl-xL as well as resistance to apoptosis after exposure to chemotherapeutics drugs. In contrast, the treatment of Ramos cells with 2-methoxyestradiol, an inhibitor of HIF-1α activity, induced down-regulation of Bcl-xL expression, and this correlated with the sensitization of tumor cells to chemotherapeutic drugs. These data demonstrate that up-regulation of the anti-apoptotic protein Bcl-xL in NHL cells correlates with HIF-1α expression and activity, through which a phenotype of chemoresistance is induced.

Prevalence of human papillomavirus genotypes, and mucosal IgA anti-viral responses in women with cervical ectopy.

BACKGROUND Data on the prevalence of different human papillomavirus (HPV) genotypes and the associated mucosal immune response in women with cervical ectopy are scarce. OBJECTIVE To assess the prevalence of different HPV genotypes and the mucosal anti-viral immune response in cervical ectopy. STUDY DESIGN Detection and typing of HPV DNA was determined in 141 women with cervical ectopy, 272 cytologically normal controls and 98 low-grade squamous intraepithelial lesions (LSIL) by PCR and direct sequencing. Mucosal IgA antibodies to HPV16 and HPV18 were evaluated in cervical mucus by ELISA. RESULTS The prevalence of HPV in cervical ectopy was higher (73.7%) than that observed in control samples (30.5% in endocervix, and 1.8% in exocervix), but similar to the prevalence in LSIL (62.2%). Typing showed that the overall distribution frequency concerned 14 different genotypes, with HPV18 being the most prevalent in cervical ectopy (53.9%), whereas HPV16 predominated in LSIL (38.7%). High-risk HPV genotypes were 2.2 times more frequent in cervical ectopy than in the normal endocervix (p<0.0001). HPV infection in cervical ectopy patients was accompanied by a mucosal IgA-antibody response. Antibody reactivity to HPV18 was significantly higher than the response to HPV16. CONCLUSION Cervical ectopy is a risk factor for infection with high-risk HPV genotypes, in particular HPV18. Our results emphasize the need of further studies to clarify the oncogenic potential of this virus in cervical ectopy.

Adjuvants in tuberculosis vaccine development

Tuberculosis remains a major public health problem around the world. Because the Mycobacterium bovis Bacilli-Calmette-Guerin (BCG) vaccine fails to protect adults from pulmonary tuberculosis, there is an urgent need for improved vaccine formulations. Unlike BCG, recombinant vaccines purified from bacterial expression vectors, as well as naked DNA, require an additional adjuvant. Recent improvements in our understanding of disease immunopathology, together with advances in biochemical and molecular techniques, have permitted the successful development of promising tuberculosis vaccine delivery and adjuvant combinations for human use. Here, we summarize the current state of adjuvant development and its impact on tuberculosis vaccine progress.

Nucleo-cytoplasmic transport of estrogen receptor alpha in breast cancer cells

Approximately 70% cases of breast cancers exhibit high expression and activity levels of estrogen receptor alpha (ERα), a transcription regulator that induces the expression of genes associated with cellular proliferation and survival. These nuclear functions of the receptor are associated with the development of breast cancer. However, ERα localization is not static, but rather, dynamic with continuous shuttling between the nucleus and the cytoplasm. Interestingly, both the nuclear import and export of ERα are modulated by several stimuli that include estradiol, antiestrogens, and growth factors. As ERα nuclear accumulation is critical to the regulation of gene expression, nuclear export of this receptor modulates the intensity and duration of its transcriptional activity. Thus, the subcellular spatial distribution of ERα ensures tight modulation of its concentration in cellular compartments, as well as of its nuclear and extranuclear functions. In this review, we will discuss current findings regarding the biological importance of molecular mechanisms of, and proteins responsible for, the nuclear import and export of ERα in breast cancer cells.

IL-2 Enhances Cervical Cancer Cells Proliferation and JAK3/STAT5 Phosphorylation at Low Doses, While at High Doses IL-2 Has Opposite Effects

The IL-2R signaling is critical for normal lymphocyte proliferation. However, the role of the IL-2 signaling in cervical cancer is not yet fully understood. We show that in IL-2R-expressing cervical cancer cells, JAK1 molecules are not phosphorylated. At low doses of IL-2, the constitutive phosphorylation of JAK3 and STAT5 increases in the tumor cells and decreases in lymphocytes, whereas the opposite occurs at high doses of IL-2. Using AG-490, the activation of JAK3 and the proliferation of cervical cancer cells were inhibited. We describe differences in the response of molecules downstream the IL-2R in lymphocytes and tumor cells.

Peripheral blood lymphocytes from low-grade squamous intraepithelial lesions patients recognize vaccine antigens in the presence of activated dendritic cells, and produced high levels of CD8+IFNγ+T cells and low levels of IL-2 when induced to proliferate

BackgroundMost infections with human papillomavirus (HPV) are resolved without clinical intervention, but a minority evolves into chronic lesions of distinct grades, including cervical-uterine cancer. It is known that in most cases the immune system mediates elimination of HPV infection. However, the mechanism of immune evasion leading to HPV persistence and development of early cervical lesions is not fully understood. The aim of the present work was to evaluate the potential of peripheral blood leukocytes (PBL) from low-grade squamous intraepithelial lesions (LSIL) patients to be activated ex-vivo by vaccine antigens, the participation of cytotoxic lymphocytes and regulatory T cells, and to determine the secretion of Th1 and Th2 cytokines mediated by stimulation of T cell receptors.ResultsWe found that PBL from LSIL patients showed a significantly lower proliferation rate to vaccine antigens as compared to that of healthy donors, even though there was not a difference in the presence of antibodies to those antigens in sera from both groups. We did not find differences in either the frequency of CD4 + CD25 + FoxP3+ in PBL, or the levels of IL-4, IL-5 and IL-10 in plasma or conditioned media from PBL incubated with TcR agonists in vitro, between the two groups. However, we detected a lower production of IL-2 and a higher proportion of CD8 + IFNγ + cells in PBL from LSIL patients as compared with PBL from normal donors. We also observed that PBL from patients infected by HPV-16 and −18 were not able to proliferate in the presence of soluble HPV antigens added to the culture; however, a high level of proliferation was attained when these antigens were presented by activated dendritic cells.ConclusionsOur results suggest that the immunodeficiency reported in LSIL patients could be due to the inability of specific cytotoxic T lymphocytes that for some unknown reason are present but unable to mount a response when challenged with their antigens, probably related to an in situ IL-2 production deficiency.

Dehydroepiandrosterone Inhibits Events Related with the Metastatic Process in Breast Tumor Cell Lines

ABSTRACT Dehydroepiandrosterone (DHEA), an adrenal hormone, has a protective role against cancer. We previously shown that DHEA inhibits the proliferation and migration of cell lines derived from breast cancer; however, the role of DHEA in others events related with these effects are unknown. We hypothesized that DHEA inhibits the expression of proteins and some events related with cell migration and metastasis. We determined the migration in Boyden chambers, the invasion in matrigel, anchorage-independent growth and the formation of spheroids in 3 cell lines (MCF-7, MDA-MB-231, ZR-75-30) derived from breast cancer exposed to DHEA. The secretion of metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), and several pro-inflammatory molecules in the secretome of these cells was also evaluated.  DHEA inhibited the migration in transwells and the invasion in matrigel of MCF-7 and MDA-MB-231 cells. Besides, DHEA inhibited the anchorage-independent growth on agar and decreased the size of spheroids, and also reduced the secretion of IL-1α, IL-6, IL-8, and TNF-α in all cell lines. Metalloproteinase-1 (MMP-1) secretion was slightly decreased by DHEA treatment in MDA-MB-231 cells. Our results also showed that inhibition of migration and invasion induced by DHEA in breast cancer cells is correlated with the decrease of cytokine/chemokine secretion and the diminution of tumor cells growth.  MCF-7 cells were the most responsive to the exposure to DHEA, whereas ZR-75-30 cells responded less to this hormone, suggesting that DHEA could be used in the treatment of breast cancer in early stages.