Expression of MICA, MICB and NKG2D in human leukemic myelomonocytic and cervical cancer cells

<p>Abstract</p> <p>Background</p> <p>Cancer cells are known to secrete the stress molecules MICA and MICB that activate cytotoxicity by lymphocytes and NK cells through their NKG2D receptor as a mechanism of immunological defense. This work was undertaken to evaluate if cancer cells can also express this receptor as a possible mechanisms of depletion of MIC molecules and thus interfere with their immune recognition.</p> <p>Methods</p> <p>Myelomonocytic leukemic (TPH-1 and U-937) and cervical cancer (CALO and INBL) cell lines were evaluated by Western Blot, ELISA, flow cytometry and immunocytochemistry to evaluate their capacity to express and secrete MICA and MICB and to be induced to proliferate by these molecules as well as to express their receptor NKG2D. Statistical analysis was performed by two-way ANOVA for time course analysis and Student's t-test for comparison between groups. Values were considered significantly different if p < 0.05.</p> <p>Results</p> <p>THP-1 and U-937 produce and secrete the stress MICA and MICB as shown by Western Blot of lysed cells and by ELISA of their conditioned media. By Western Blot and flow cytometry we found that these cells also express the receptor NKG2D. When THP-1 and U-937 were cultured with recombinant MICA and MICB they exhibited a dose dependent induction for their proliferation. CALO and INBL also produce MICA and MICB and were induced to proliferate by these stress molecules. By Western Blot, flow cytometry and immunocytochemistry we also found that these cells express NKG2D.</p> <p>Conclusions</p> <p>Our novel results that tumor cells can simultaneously secrete MIC molecules and express their receptor, and to be induced for proliferation by these stress molecules, and that tumor epithelial cells can also express the NKG2D receptor that was thought to be exclusive of NK and cytotoxic lymphocytes is discussed as a possible mechanism of immunological escape and of tumor growth induction.</p

El caseinato de sodio y la caseína α inhiben la proliferación de la línea celular mieloide de ratón 32D clone 3 (32Dcl3) mediante el TNF-α

Introduction: Sodium caseinate (CS) and its components (alpha-casein, beta-casein, and kappa-casein) have been shown to inhibit the proliferation of the mouse hematopoietic 32D clone 3 (32Dcl3) cell line and induce its differentiation into macrophages. It is well-known that alpha-casein induces IL-1β production and that this cytokine inhibits the proliferation via the production of tumor necrosis factor alpha (TNF-alpha), but it is not known if CS and the caseins inhibit the proliferation via TNF-alpha production.Objective: To evaluate if CS and alpha-casein, beta-casein and kappa-casein inhibit the proliferation on 32Dcl3 cell line via TNF-alpha.Materials and methods: We used different concentrations of CS, alpha-casein, betacasein and kappa-casein in 32Dcl3 cells to evaluate cell proliferation. We assessed cell viability by MTT, induction to apoptosis by flow cytometry, and TNF-alpha synthesis by ELISA. Additionally, we performed anti-TNF-alpha neutralization assays on 32Dcl3 cells treated with CS and alpha-casein and we evaluated proliferation.Results: The results showed that CS, alpha-casein, beta-casein, and kappa-casein reduced proliferation of the 32Dcl3 cell line without affecting the viability and that only CS and alpha-casein induced apoptosis and the release of TNF-alpha. The 32Dcl3 cells treated with CS and alpha-casein reestablished their proliferation by using anti-TNF-alpha antibodies.Conclusion: TNF-alpha was the main responsible for the inhibition of proliferation in 32Dcl3 cells treated with CS or alpha-casein.Introducción. Se ha demostrado que el caseinato de sodio y sus componentes (caseínas α, β y κ) inhiben la proliferación de la línea celular hematopoyética de ratón 32D clone 3 (32Dcl3) e inducen su diferenciación hacia macrófagos. Se sabe que la caseína α induce la producción de IL-1β y que esta última citocina inhibe la proliferación celular mediante la producción del factor de necrosis tumoral alfa (TNF-α), pero se desconoce si el caseinato de sodio y las caseínas inducen la producción de TNF y si este es el responsable de la inhibición de la proliferación.Objetivo. Evaluar si el caseinato de sodio y las caseínas α, β y κ inhiben la proliferación de la línea celular 32Dcl3 mediante la producción de TNF-α.Materiales y métodos. Se usaron diferentes concentraciones de caseinato de sodio y de las caseínas α, β y κ en las células 32Dcl3. Posteriormente, se evaluaron la viabilidad celular mediante una prueba con el MTT [3-(4,5-dimetiltiazol-2-ilo)-2,5-difeniltetrazol], la inducción de apoptosis con la citometría de flujo y la síntesis del TNF-α con el ELISA. Además, se hicieron pruebas de neutralización con anti-TNF-α en células 32Dcl3 tratadas con caseinato de sodio y caseína α, y se evaluó la proliferación celular.Resultados. Se encontró que el caseinato de sodio y las caseínas α, β y κ reducían la proliferación de la línea celular 32Dcl3 sin afectar la viabilidad, y que solo el caseinato y la caseína α inducían la apoptosis y la liberación al medio de TNF-α. La proliferación de células 32Dcl3 tratadas con caseinato y caseína α se restableció al usar anticuerpos anti-TNF-α. Conclusión. El TNF-α fue el principal responsable de la inhibición de la proliferación en las células 32Dcl3 tratadas con caseinato de sodio o caseína α

An HPV 16 L1-based chimeric human papilloma virus-like particles containing a string of epitopes produced in plants is able to elicit humoral and cytotoxic T-cell activity in mice

<p>Abstract</p> <p>Background</p> <p>Even though two prophylactic vaccines against HPV are currently licensed, infections by the virus continue to be a major health problem mainly in developing countries. The cost of the vaccines limits wide-scale application in poor countries. A promising strategy for producing affordable and efficient vaccines involves the expression of recombinant immunogens in plants. Several HPV genes have been expressed in plants, including L1, which can self-assemble into virus-like particles. A plant-based, dual prophylactic/therapeutic vaccine remains an attractive possibility.</p> <p>Results</p> <p>We sought to express in tomato plants chimeric HPV 16 VLPs containing L1 fused to a string of epitopes from HPV 16 E6 and E7 proteins. The L1 employed had been modified to eliminate a strong inhibitory region at the 5' end of the molecule to increase expression levels. Several tomato lines were obtained expressing either L1 alone or L1-E6/E7 from 0.05% to 0.1% of total soluble protein. Stable integration of the transgenes was verified by Southern blot. Northern and western blot revealed successful expression of the transgenes at the mRNA and protein level. The chimeric VLPs were able to assemble adequately in tomato cells. Intraperitoneal administration in mice was able to elicit both neutralizing antibodies against the viral particle and cytotoxic T-lymphocytes activity against the epitopes.</p> <p>Conclusion</p> <p>In this work, we report for the first time the expression in plants of a chimeric particle containing the HPV 16 L1 sequence and a string of T-cell epitopes from HPV 16 E6 and E7 fused to the C-terminus. The particles were able to induce a significant antibody and cytotoxic T-lymphocytes response. Experiments <it>in vivo </it>are in progress to determine whether the chimeric particles are able to induce regression of disease and resolution of viral infection in mice. Chimeric particles of the type described in this work may potentially be the basis for developing prophylactic/therapeutic vaccines. The fact that they are produced in plants, may lower production costs considerably.</p

A novel HPV 16 L1-based chimeric virus-like particle containing E6 and E7 seroreactive epitopes permits highly specific detection of antibodies in patients with CIN 1 and HPV-16 infection

<p>Abstract</p> <p>Background</p> <p>The presence of IgG antibodies to HPV-16 L1-virus like particles (VLPs) in serum has been reported as a result of persistent exposure to the virus and as a marker of disease progression. However, detection of VLP-specific antibodies in sera does not always indicate a malignant lesion as positive results may also be due to a nonmalignant viral infection. Furthermore, malignant lesions are associated with an increased antibody titer for E6 and E7 proteins. The aim of this study was to develop an ELISA using a novel chimeric virus-like particle (cVLP) encoding an L1 protein fused with a string of HPV-16 E6 and E7 seroreactive epitopes to its C-terminus to be used for detection of HPV-16 specific antibodies in patients with cervical intraepithelial lesion grade 1 (CIN 1).</p> <p>Results</p> <p>The sera of 30 patients with CIN 1 who also tested positive for HPV-16 DNA and of 30 age-matched normal donors negative for HPV infection were tested for the presence of IgG antibodies specific for either VLP-L1 (HPV-16 L1), gVLP (derived from Gardasil), or cVLP by ELISA. The cVLP-reactive sera yielded two distinct groups of results: (H) reactivity levels that presented very strong cVLP-specific titers, and (L) reactivity levels with significantly lower titers similar to those obtained with VLP-L1 and gVLP antigens. Additionally, the sera that presented the higher cVLP titers closely matched those that had significantly stronger reactivity to E6 and E7 epitopes. Interestingly, the samples with the highest titers corresponded to patients with the higher numbers of sexual partners and pregnancies. On the other hand only 4 out of the 12 sera that harbored antibodies with VLP neutralizing ability corresponded to the group with high cVLP antibody titers.</p> <p>Conclusion</p> <p>We report for the first time that chimeric particles containing HPV-16 L1 protein fused with E6 and E7 seroreactive epitopes enable much better detection of IgG antibodies in the sera of CIN 1 patients positive for HPV-16 infection than those obtained with VLPs containing only the HPV-16 L1 protein. We also found that the sera with higher cVLP antibody titers corresponded to patients with more sexual partners and pregnancies, and not always with to those with a high neutralizing activity. This novel assay could help in the development of a tool to evaluate cervical cancer risk.</p

Pleiotropic Effects of IL-2 on Cancer: Its Role in Cervical Cancer

IL-2 receptor (IL-2R) signalling is critical for normal lymphocyte proliferation, but its role in cervical cancer is not fully understood. The receptor is composed of three chains: IL-2α, IL-2β, and IL-2γ. Intracellular signalling is initiated by ligand-induced heterodimerization of the IL-2β and IL-2γ chains, resulting in the activation of multiple intracellular kinases. Recently, IL-2R was shown to be expressed on nonhaematopoietic cells, especially on several types of tumour cells. However, the function of this receptor on malignant cells has not been clearly defined. The expression of IL-2R and the production of IL-2 in cervical cancer cells have been documented as well as expression of molecules of the JAK-STAT pathway. In the current review we have highlighted the differences in the responses of molecules downstream from the IL-2R in normal lymphocytes and tumour cells that could explain the presence of tumour cells in an environment in which cytotoxic lymphocytes also exist and compete and also the effect of different concentrations of IL-2 that could activate effector cells of the immune system cells, which favour the elimination of tumour cells, or concentrations that may promote a regulatory microenvironment in which tumour cells can easily grow

Cervical Cancer Cells Express Markers Associated with Immunosurveillance

Cervical cancer is the second most frequent cancer in women in Mexico, and its development depends on the presence of human papillomaviruses in the uterine cervix. These oncogenic viruses transform cells where the control over cell cycle disappears, and the capacity to induce apoptosis is absent. On the other hand, some mutations confer to the transformed cells the ability to evade recognition by the immune system. The expression of markers of the immune system such as CD95, MICA/B, CD39, CD73, NKp30, NKp46, CD44, CD24, NKG2A, and CTLA-4 was analysed by flow cytometry on cervical cancer cells INBL (HPV 18, stage IVB), HeLa (HPV 18), CaSki (HPV 16), and C33A (HPV-). Our results showed the presence of atypical markers on cervical cancer cells; some of them are molecules involved in tumour cell recognition such as MICA/B and CD95. Other markers associated with immune system escape, such as CD39, CD73, and CTLA-4, were also present. Furthermore, we found that some cervical cancer cells expressed typical markers of NK cells like NKp30, NKp46, NKG2A, and KIR3DL1. It is not clear whether these molecules confer any gain to the tumour cells or if they represent a disadvantage, but we hypothesise that these molecules that are present in cervical cancer cells allow them to mimic in front of the immune system