Anticancer Activity of HER2-targeting CPP-PTEN-THP Chimeric Proteins.

BACKGROUND/AIM: Protein phosphatase and tensin homolog (PTEN) is a tumor suppressor protein with potential to be a new biotechnological drug for PTEN-deficient cancer treatment. This study aimed to develop PTEN-based chimeric proteins (CPP-PTEN-THP) for human epidermal growth factor receptor 2 (HER2)-positive breast cancer treatment, addressing current limitations like inadequate delivery, poor tumor penetration, and low selectivity, while assessing their potential HER2-specific anticancer effects. MATERIALS AND METHODS: pCEFL-EGFP vector was used for both TAT-PTEN-LTV and KLA-PTEN-LTV construction. Non-contact co-cultures were employed using HEK-293T cells for protein expression, and HCC-1954 and MCF-7 cell lines for cytotoxicity testing. Protein detection was analyzed by western blotting and a docking prediction analysis was performed to infer the interactions. RESULTS: Endogenous and recombinant PTEN protein expression was confirmed in cell lysates. A 54-kDa signal matching the theoretical size of PTEN was detected, showing a greater level in TAT-PTEN-LTV (215.1±26.45%) and KLA-PTEN-LTV (129.2±1.44%) compared to endogenous PTEN. After the noncontact co-culture method, cytotoxic studies showed HCC-1954 preferential cell inhibition growth, with 25.95±0.9% and 12.25±1.29% inhibition by KLA-PTEN-LTV and TAT-PTEN-LTV respectively, compared to MCF-7 cells. An LTV-HER2 interaction model was proposed, inferring that LTV interactions are mainly due to the Pro, Trp, and Tyr residues that target HER2. CONCLUSION: The developed PTEN-based chimeric proteins have HER2-specific anticancer activity against HCC-1954 cells.

Long-term antigen-specific immune response by an oncolytic adenovirus encoding SP-SA-E7-4-1BBL in HPV-16 cancer model.

BACKGROUND: To describe an oncolytic adenovirus (OAd) encoding SP-SA-E7-4-1BBL that is capable of inducing tumor regression in therapeutic assays. Herein, we tested whether the antitumor effect is given by the induction of a tumor-specific immune response, as well as the minimum dose needed to elicit antitumor protection and monitor the OAd biodistribution over time. METHODS AND RESULTS: C57BL/6 mice (n = 5) per group were immunized twice with OAds encoding SP-SA-E7-4-1BBL, SA-E7-4-1BBL, or SP-SA-4-1BBL and challenged with TC-1 cancer cells. The DNA construct SP-SA-E7-4-1BBL was employed as a control via biolistic or PBS injection. Groups without tumor development at 47 days were rechallenged with TC-1 cells, and follow-up lasted until day 90. The minimum dose of OAd to induce the antitumor effect was established by immunization using serial dilution doses. The cytometry bead assay and the ELISpot assay were used to evaluate cytokine release in response to ex vivo antigenic stimulation. The distribution profile of the OAd vaccine was evaluated in the different organs by histological, immunohistochemical and qPCR analyses. The OAd SP-SA-E7-4-1BBL-immunized mice did not develop tumors even in a rechallenge. A protective antitumor effect was observed from a dose that is one hundredth of most reports of adenoviral vaccines. Immunization with OAd increases Interferon-gamma-producing cells in response to antigen stimulation. OAd was detected in tumors over time, with significant morphological changes, contrary to nontumor tissues. CONCLUSIONS: The OAd SP-SA-E7-4-1BBL vaccine confers a prophylactic, safe, long-lasting, and antigen-dependent antitumor effect mediated by a Th1 antitumor immune response.

Análisis crítico del programa de la asignatura Genética Médica de la disciplina Investigaciones Diagnósticas / A Critical Analysis of the Syllabus for the Subject Medical Genetics of the Discipline Diagnostic Research

Introducción: El programa de estudio es una formulación hipotética de los aprendizajes que se pretenden lograr en el educando. Constituye una herramienta fundamental de trabajo docente. Objetivo: Exponer un análisis crítico del programa de estudio de la asignatura Genética Médica en la carrera de medicina, a partir de lo normado en el reglamento vigente para el trabajo docente-metodológico. Métodos: Se realizó una revisión bibliográfica para desarrollar un análisis crítico del programa de la asignatura genética médica, en la que se consideraron artículos publicados entre 2012 y 2022. La búsqueda fue realizada en Google académico, Dialnet, SciELO y Redalyc en septiembre de 2022. Las palabras clave utilizadas fueron: programas, genética, asignatura, disciplina y proceso docente-educativo. Dentro de este marco se incluyeron todos los artículos cubanos publicados; no hubo restricción en cuanto al idioma. Se consultaron 50 artículos, de estos 11 fueron seleccionados. Se excluyeron aquellos no relacionados con la educación médica superior. Resultados: Se orientó metodológicamente la inclusión de aspectos encaminados a la promoción de salud; fomentar las habilidades comunicativas; reformular los objetivos, incluyendo en su estructura los elementos esenciales; realizar un cambio en el orden de impartir el contenido, con modificaciones, además, en el nivel de profundidad y con aporte de un enfoque preventive; y declarar adecuadamente los valores, la rectificación de la cantidad de horas del fondo de tiempo y la actualización de la bibliografía. Conclusiones: Las insuficiencias encontradas en el análisis efectuado identificaron las áreas vulnerables hacia donde deben dirigirse las principales acciones encaminadas a aumentar la calidad del proceso docente educativo y reflejaron la necesidad de su reevaluación(AU)

Introduction: The syllabus is a hypothetical formulation of the learning aspects intended to be achieved in the student. It is a fundamental tool for teaching. Objective: To present a critical analysis of the syllabus for subject Medical Genetics in the medical major, based on the current regulations for the teaching-methodological work. Methods: A literature review was carried out to develop a critical analysis of the syllabus of the subject Medical Genetics, considering articles published between 2012 and 2022. The search was performed in Google Scholar, Dialnet, SciELO and Redalyc in September 2022. The keywords used were programas [syllabuses], genética [genetics], asignatura [subject], disciplina [discipline] and proceso docente-educativo [teaching-educational process]. This framework included all published Cuban articles; there were not any language-related restrictions. Fifty articles were consulted, 11 of which were selected. Those not related to higher medical education were excluded. Results: The methodological orientation was to include aspects aimed at health promotion, to encourage communicative skills, to reformulate the objectives (including the essential elements in their structure), to make a change in the order of teaching (with modifications also in the level of depth and contributing with a preventive approach), as well as to state the values adequately, to rectify the number of hours within the available time fund, to update the bibliography. Conclusions: The insufficiencies found through the performed analysis permitted to identify the vulnerable areas towards the main actions should be directed if aimed at increasing the quality of the educational teaching process, apart from reflecting their need to be reassessed(AU)

Enhanced antitumor activity induced by a DNA vaccine encoding E7 antigen fused to an ERAD-targeting sequence.

The endoplasmic reticulum (ER) is a key organelle in cell homeostasis and cell health through antigen presentation to immune cells. Thus, the ER has become a therapeutic target to induce cellular immune responses. We previously reported the antitumor effect of a DNA vaccine that expresses the E7 antigen fused to the cyclooxygenase-2 (COX-2) protein. This inflammation-related enzyme contains a degradation cassette associated with the endoplasmic reticulum-associated degradation (ERAD) pathway. To avoid the use of full-length COX-2 and any risk of adverse effects due to the activity of its catalytic site, we designed new versions of the fusion protein. These new constructs encode the E7 antigen fused to the signal peptide and the ERAD sequence of COX-2 with or without the membrane-binding domain (MBD) as well as deletion of the catalytic site. We evaluated the antigen-specific antitumor effect of these DNA constructs in murine prophylactic and therapeutic cancer models. These assays showed that the ERAD cassette is the minimum sequence in the COX-2 protein that induces an antitumor effect when fused to the E7 antigen with the advantage of eliminating any potential adverse effects from the use of full-length COX-2.

Chronic diseases: Origin and cell mechanisms involved.

Chronic diseases are a worldwide health problem directly related to society, lifestyle, and the development of unhealthy habits over time. Cardiovascular disease, cancer, chronic respiratory disease, and diabetes are the main causes of death. Environmental factors, such as air pollutants, poor diet, genetic predisposition, or a combination of these, are related to the development of these diseases. These factors activate cell mechanisms, such as DNA damage, oxidative stress, endoplasmic reticulum stress, autophagy, inflammation, and cell death. Depending on the dose and duration of exposure to causative agents, this cell damage can be acute or chronic. Activating these cell mechanisms can rescue normal cell function and cause permanent damage, unleashing the degeneration of tissues and organs over time. A wide variety of treatments help control chronic diseases; however, they cannot be cured completely. This fact leads to complications, dysfunctions, and disabilities. Herein, we discuss some of the principal mechanisms involved and how cellular stress can lead to these diseases when they persist for a long time.

Cerebrolysin induces hair repigmentation associated to MART-1/Melan-A reactivation.

Hair graying, a prototypical sign of human aging, is a progressive loss of pigmentation from growing hair shafts caused by disease and as a side effect of medications. Cerebrolysin is a neuropeptide preparation that mimics the effect of endogenous neurotrophic factors. Cerebrolysin has been widely used in neurologic conditions, such as cerebral stroke, Alzheimer's disease, and dementia, among others. Cerebrolysin treatment has achieved to regain or maintain the cognitive ability of affected patients; however, up to date, there are no reports about the reactivation of hair pigmentation. We describe a previously not described effect occurring on patients receiving Cerebrolysin treatment for neurologic diseases and whether this effect is associated in reactivation of melanocytes and melanin expression. Here, we report five patients (mean age, 70.6 years), who also had age-related hair graying and scalp hair repigmentation during Cerebrolysin treatment. Macroscopic analysis revealed hair repigmentation consisted in diffuse darkening of the scalp hair. Impregnation and immunostaining analysis were performed on scalp biopsies taken before and after Cerebrolysin treatment; the results showed greater melanin and melanocyte marker MART-1/Melan-A staining following Cerebrolysin treatment. We present, to our knowledge, the first report on hair repigmentation is a previously not described effect occurring following Cerebrolysin treatment.

Plasmid DNA for Therapeutic Applications in Cancer.

Recently, the interest in using nucleic acids for therapeutic applications has been increasing. DNA molecules can be manipulated to express a gene of interest for gene therapy applications or vaccine development. Plasmid DNA can be developed to treat different diseases, such as infections and cancer. In most cancers, the immune system is limited or suppressed, allowing cancer cells to grow. DNA vaccination has demonstrated its capacity to stimulate the immune system to fight against cancer cells. Furthermore, plasmids for cancer gene therapy can direct the expression of proteins with different functions, such as enzymes, toxins, and cytotoxic or proapoptotic proteins, to directly kill cancer cells. The progress and promising results reported in animal models in recent years have led to interesting clinical results. These DNA strategies are expected to be approved for cancer treatment in the near future. This review discusses the main strategies, challenges, and future perspectives of using plasmid DNA for cancer treatment.

Effect of Diameter and Fenestration Area of the Liposuction Cannula on the Viability of the Adipocytes.

BACKGROUND: Loss of volume is perhaps the most frustrating problem of fat grafting. The process of fat grafting depends on different variables such as harvesting, processing, and injection techniques. Results between studies that evaluate the effect of the cannula size on fat graft survival have been controversial. However, the role of the fenestration area of the cannula has not been described. METHODS: Four custom-made cannulas with a single fenestration were used for this study. Cannulas vary in diameter and area of the fenestration. Healthy patients seeking primary liposuction of the abdomen for aesthetic reasons were included. Lipoaspiration was performed in a clockwise pattern, and the order of the cannulas was rotated. Negative pressure was maintained at 0.8 atm at all times. Ten ml of fat, obtained from the suction tube, was poured into 20-ml conical centrifugal tubes for further processing. One gram of lipoaspirate was extracted from each sample, and acridine orange stain was added. Adipocytes were extracted, extended in a frotis, and observed by a histologist (masked fashion) under fluorescence microscopy. Viability was reported in percentages per sample. RESULTS: The overall viability was 64.75% ± 18.58. The viability of the obtained samples ranged from 66.51± 20.66 % to 62.83 ± 18.1. In further analysis, comparing the viability according to the shaft diameter and fenestration area, there was no significant difference among groups. CONCLUSIONS: Neither the diameter of the cannula nor the size of the fenestrations are determining factors to affect the viability of the adipocytes. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

4-1BBL as a Mediator of Cross-Talk between Innate, Adaptive, and Regulatory Immunity against Cancer.

The ability of tumor cells to evade the immune system is one of the main challenges we confront in the fight against cancer. Multiple strategies have been developed to counteract this situation, including the use of immunostimulant molecules that play a key role in the anti-tumor immune response. Such a response needs to be tumor-specific to cause as little damage as possible to healthy cells and also to track and eliminate disseminated tumor cells. Therefore, the combination of immunostimulant molecules and tumor-associated antigens has been implemented as an anti-tumor therapy strategy to eliminate the main obstacles confronted in conventional therapies. The immunostimulant 4-1BBL belongs to the tumor necrosis factor (TNF) family and it has been widely reported as the most effective member for activating lymphocytes. Hence, we will review the molecular, pre-clinical, and clinical applications in conjunction with tumor-associated antigens in antitumor immunotherapy, as well as the main molecular pathways involved in this association.

Prevalence of IgG antibodies induced by the SARS-COV-2 virus in asymptomatic adults in Nuevo Leon, Mexico.

Population-based immunoglobulin G (IgG) seroprevalence studies in asymptomatic individuals in Latin America are scarce. The objective of the study was to estimate the prevalence and geographic distribution of IgG antibodies induced by natural SARS-CoV-2 infection in asymptomatic adults, 5-8 months after the first case was reported in a northeastern state of Mexico. This was a population-based cross-sectional study carried out in Nuevo Leon during August-November 2020. Individuals ≥18 years with no previous diagnosis or symptoms suggestive of COVID-19 were consecutively screened in one of the busiest subway stations. Also, a search for eligible individuals was done from house-to-house, after selecting densely populated geographic sectors of each of the municipalities of the metropolitan area (n = 4495). The IgG antibodies to SARS-CoV-2 nucleocapsid protein were analyzed. The IgG antibody positivity rate was 27.1% (95% confidence interval [CI]: 25.8, 28.4); there were no differences by sex or age (p > 0.05). Analysis by month showed a gradual increase from 11.9% (August) to 31.9% (November); Week 39 had the highest positivity rate (42.2%, 95% CI: 34.2, 50.7). Most people did not have evidence of previous SARS-CoV-2 infection. Preventive measures and promotion of the COVID-19 vaccine should be strengthened.

Targeting E7 antigen to the endoplasmic reticulum degradation pathway promotes a potent therapeutic antitumor effect.

It has been previously reported that targeting and retaining antigens in the endoplasmic reticulum (ER) can induce an ER stress response. In this study, we evaluated the antitumor effect of E7 antigen fused to an ERresident protein, cyclooxygenase-2, which possesses a 19-aminoacid cassette that directs it to the endoplasmic reticulum-associated protein degradation (ERAD) pathway. The featured DNA constructs, COX2-E7 and COX2-E7ΔERAD, with a deletion in the 19-aminoacid cassette, were used to evaluate the importance of this sequence. In vitro analysis of protein expression and ER localisation were verified. We observed that both constructs induced an ER stress response. This finding correlated with the antitumor effect in mice injected with TC-1 cells and treated with different DNA constructs by biolistic vaccination. Immunisation with COX2-E7 and COX2-E7ΔERAD DNA constructs induced a significant antitumor effect in mice, without a significant difference between them, although the COX2-E7 construct induced a significant E7-specific immune response. These results demonstrate that targeting the E7 antigen to the ERAD pathway promotes a potent therapeutic antitumor effect. This strategy could be useful for the design of other antigen-specific therapies.

An Oncolytic Adenovirus Encoding SA-4-1BBL Adjuvant Fused to HPV-16 E7 Antigen Produces a Specific Antitumor Effect in a Cancer Mouse Model.

Human papillomaviruses (HPVs) are responsible for about 25% of cancer cases worldwide. HPV-16 E7 antigen is a tumor-associated antigen (TAA) commonly expressed in HPV-induced tumors; however, it has low immunogenicity. The interaction of 4-1BBL with its receptor induces pleiotropic effects on innate, adaptive, and regulatory immunity and, if fused to TAAs in DNA vaccines, can improve the antitumor response; however, there is low transfection and antitumor efficiency. Oncolytic virotherapy is promising for antitumor gene therapy as it can be selectively replicated in tumor cells, inducing cell lysis, and furthermore, tumor cell debris can be taken in by immune cells to potentiate antitumor responses. In this study, we expressed the immunomodulatory molecule SA-4-1BBL fused to E7 on an oncolytic adenovirus (OAd) system. In vitro infection of TC-1 tumor cells and NIH-3T3 non-tumor cells with SA/E7/4-1BBL OAd demonstrated that only tumor cells are selectively destroyed. Moreover, protein expression is targeted to the endoplasmic reticulum in both cell lines when a signal peptide (SP) is added. Finally, in an HPV-induced cancer murine model, the therapeutic oncolytic activity of OAd can be detected, and this can be improved when fused to E7 and SP.

In vitro antitumor, pro-inflammatory, and pro-coagulant activities of Megalopyge opercularis J.E. Smith hemolymph and spine venom.

Contact with stinging spines venom from several Lepidoptera larvae may result in skin lesions. In Mexico, envenomation outbreaks caused by Megalopyge opercularis were reported between 2015 and 2016. The aim of this study was to identify the venomous caterpillars in Nuevo Leon, Mexico and evaluate several biological activities of their hemolymph (HEV) and spine setae (SSV) venoms. M. opercularis was identified by cytochrome oxidase subunit (COI) designed primers. HEV and SSV extracts cytotoxic activity was assessed on the L5178Y-R lymphoma cell line. For apoptotic cells number and apoptosis, cells were stained with acridine orange/ethidium bromide and validated by DNA fragmentation. Human peripheral blood mononuclear cells (hPBMC) cytokine response to the extracts was measured by the cytometric bead array assay. Extracts effect on pro-coagulation activity on human plasma was also evaluated. HEV and SSV extracts significantly inhibited (p < 0.01) up to 63% L5178Y-R tumor cell growth at 125-500 µg/mL, as compared with 43% of Vincristine. About 79% extracts-treated tumor cells death was caused by apoptosis. Extracts stimulated (p < 0.01) up to 60% proliferation of resident murine lymphocytes, upregulated IL-1ß, IL-6, IL-8, and TNF-α production by hPBMC, and showed potent pro-coagulant effects. The pharmacological relevance of these venoms is discussed.

Antitumor effect of adenoviruses expressing mutant non-oncogenic E7 versions from HPV-16 fused to calreticulin.

PURPOSE: To compare the antitumor effect of adenoviruses that express mutant variants of the protein E7 from HPV-16 fused to calreticulin. METHODS: Recombinant adenoviruses were generated to express calreticulin fused to mutant versions of E7 (CRT/E7m and CRT/E7dm). Western blot and immunofluorescence assays were made to demonstrate protein expression. Antitumor assays were performed in C57BL6 mice injected with TC-1 cell line. RESULTS: When HEK293 cells were infected with these adenoviruses, we detected that all the recombinant proteins were expressed at endoplasmic reticulum, as expected. Next, the antitumor effect was tested on a murine tumor model established by inoculation of TC-1 cell line. We detected that both Ad CRT/E7m and Ad CRT/E7dm were capable of reducing the antitumor volume when compared to Ad LacZ, which was used as negative control. No significant difference was observed when compared to Ad CRT/E7, a positive control. CONCLUSIONS: Here we demonstrated that the mutant versions of E7 HPV-16 fused to calreticulin generate similar antitumor effect than the wild type version.

Determination of the Ratio of the Decantation Time and the Separation of Components in Lipoaspirate.

Decantation of the lipoaspirate is one of the most common techniques used to prepare the fat graft. The aim of the study was to determine the ideal time of decantation that provides the best separation of the components without compromising the viability of the adipocytes. METHODS: Thirty milliliters of fat were obtained from 11 healthy adults and decanted at room temperature for 0, 30, and 60 minutes. After decantation, the infiltration liquid and the remnant fat were measured with a volumetric pipette. Once the solution was removed, the remnant fat was centrifuged at 3000 rpm for 5 minutes to separate any residual solution, to measure the amount of actual fat obtained at that time point. Viability was determined with trypan blue staining for all the samples. RESULTS: After decantation, 9.4 ± 0.79 mL of fat was obtained at time 0, whereas 7.7 ± 1.56 mL was obtained at 30 minutes and 6.9 ± 0.92 mL at 60 minutes. Actual fat volume was 6.6 ± 1.56 mL, 5.5 ± 1.39, and 5.26 ± 1.3 mL, respectively. Viability at time 0 was 73.33 ± 0.06%, 72.57 ± 0.1% at 30 minutes, and 59.3 ± 0.09% at 60 minutes (P = 0.004). RESULTS: The fat grafting, processed by decantation, will have the best performance within a period of 30 minutes after harvesting, where the best rate of viability and separation of components will be achieved.

Neurodegeneration, demyelination, and astrogliosis in rat spinal cord by chronic lead treatment.

Early exposure to lead (Pb) has been associated with an elevated risk of developing neurodegenerative diseases. There is evidence that neuronal damage in chronic Pb exposure can be caused by the convergence of glial damage. Apoptosis may be a possible mechanism of Pb-induced cell death in the central nervous system. We tested cellular damage and apoptosis in the spinal cord of Wistar rats treated with Pb. Twelve rats were divided into two groups (n = 6): the control group was treated with only drinking water and the other group received 500 ppm of Pb acetate. After 3 months of Pb treatment, all animals were euthanized and spinal cords were extracted. Morphology was evaluated by Nissl and Kluver-Barrera stainings. Apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Specific antibodies were used to evaluate Pb damage in oligodendrocytes, astrocytes, and microglia. A large number of apoptotic bodies was observed in the white matter of the Pb-treated group. The Pb-treated group also showed a reduced number of neurons and oligodendrocytes but had an increased number of astrocytes compared with the nontreated group. Our results demonstrate that chronic Pb treatment induces neurodegeneration, demyelination, and astrogliosis in the rat spinal cord.

A DNA Vaccine Encoding SA-4-1BBL Fused to HPV-16 E7 Antigen Has Prophylactic and Therapeutic Efficacy in a Cervical Cancer Mouse Model.

The SA-4-1BBL, an oligomeric novel form of the natural ligand for the 4-1BB co-stimulatory receptor of the tumor necrosis factor (TNF) superfamily, as a recombinant protein has potent pleiotropic effects on cells of innate, adaptive, and regulatory immunity with demonstrated therapeutic efficacy in several tumor models. However, the production of soluble form of SA-4-1BBL protein and quality control is time and resource intensive and face various issues pertinent to clinical development of biologics. The present study sought to take advantage of the simplicity and translatability of DNA-based vaccines for the production and delivery of SA-4-1BBL for cancer immune prevention and therapy. A chimeric HPV-16 E7 DNA vaccine (SP-SA-E7-4-1BBL) was constructed that contains the signal peptide (SP) of calreticulin (CRT), streptavidin (SA) domain of SA-4-1BBL, HPV-16 E7 double mutant gene, and the extracellular domain of mouse 4-1BBL. Immunization by gene gun with SP-SA-E7-4-1BBL induced greater prophylactic as well as therapeutic effects in C57BL/6 mice against TC-1 tumor model compared with immunization with E7wt, SP-SA-4-1BBL or reference-positive control CRT-E7wt. The therapeutic efficacy of the DNA vaccine was associated with increased frequency of E7-specific T cells producing interferon (IFN)-γ. Overall, our data suggest that this DNA-based vaccine strategy might represent a translational approach because it provides a simpler and versatile alternative to a subunit vaccine based on SA-4-1BBL and E7 proteins.

Targeting HPV-16 antigens to the endoplasmic reticulum induces an endoplasmic reticulum stress response.

Very promising results have been observed with a deoxyribonucleic acid (DNA) vaccine based on human papillomavirus type-16 (HPV-16) antigen retention and delivery system in the endoplasmic reticulum (ER). However, the mechanism by which these antigens are processed once they reach this organelle is still unknown. Therefore, we evaluated whether this system awakens a stress response in the ER. Different DNA constructs based on E6 and E7 mutant antigens fused to an ER signal peptide (SP), a signal for retention in the ER (KDEL), or both signals (SPK), were transfected into HEK-293 cells. Overexpression of E6 and E7 antigens targeted to the ER (SP, and SPK constructs) induced ER stress, which was indicated by an increase of the ER-stress markers GRP78/BiP and CHOP. Additionally, the ER stress response was mediated by the ATF4 transcription factor, which was translocated into the nucleus. Besides, the overexpressed antigens were degraded by the proteasome. Through a cycloheximide-chase assay, we demonstrated that when both protein synthesis and proteasome were inhibited, the overexpressed antigens were degraded. Interestingly, when proteasome was blocked autophagy was increased and the ER stress response decreased. Taken together, these results indicate that the antigens are initially degraded by the ERAD pathway, and autophagy degradation pathway can be induced to compensate the proteasome inhibition. Therefore, we provided a new insight into the mechanism by which E6 and E7 mutant antigens are processed once they reach the ER, which will help to improve the development of more effective vaccines against cancer.

Antitumor Response by Endoplasmic Reticulum-Targeting DNA Vaccine Is Improved by Adding a KDEL Retention Signal.

Directing an antigen to the endoplasmic reticulum (ER) improves the antigen-specific immune response, revealing a potentially useful strategy in cancer immunotherapy using tumor-associated antigens (TAAs). This can be achieved by fusing the antigen to an ER chaperone protein, such as calreticulin (CRT). We previously reported the antitumor response by fusing the CRT signal peptide (SP) and its ER retention sequence (KDEL) to full-length human papillomavirus type 16 (HPV-16) E6 and E7 antigens, obtaining a potent antitumoral effect. In this article, we compare the antitumor response due to the use of each signal (SP and/or KDEL) fused to HPV16 E6 and E7 antigens in a DNA vaccination model. Using both SP and KDEL signals promotes higher interferon (IFN)-γ production and a faster antitumor response than using only the SP, resulting in better tumor growth restraint and higher survival, indicating that the KDEL addition to an ER-directed antigen helps by shortening the time to response. Meanwhile, antigens without signals or only the KDEL signal showed no induction of antigen-specific IFN-γ or antitumor response. Our results indicate that directing the E6E7m antigen to the ER by the SP signal is sufficient to promote an efficient antitumor response. Importantly, this effect is stronger and faster when the antigen also has an ER retention sequence, such as the KDEL signal.