Restoring Lost Anti-HER-2 Th1 Immunity in Breast Cancer: A Crucial Role for Th1 Cytokines in Therapy and Prevention

The ErbB/B2 (HER-2/neu) oncogene family plays a critical role in the development and metastatic spread of several tumor types including breast, ovarian and gastric cancer. In breast cancer, HER-2/neu is expressed in early disease development in a large percentage of DCIS lesions and its expression is associated with an increased risk of invasion and recurrence. Targeting HER-2 with antibodies such as trastuzumab or pertuzumab has improved survival, but patients with more extensive disease may develop resistance to therapy. Interestingly, response to HER-2 targeted therapies correlates with presence of immune response genes in the breast. Th1 cell production of the cytokines interferon gamma (IFNγ) and TNFα can enhance MHC class I expression, PD-L1 expression, augment apoptosis and tumor senescence, and enhances growth inhibition of many anti-breast cancer agents, including anti-estrogens and HER-2 targeted therapies. Recently, we have identified that a loss of anti-HER-2 CD4 Th1 in peripheral blood occurs during breast tumorigenesis and is dramatically diminished, even in Stage I breast cancers. The loss of anti-HER-2 Th1 response is specific and not readily reversed by standard therapies. In fact, this loss of anti-HER-2 Th1 response in peripheral blood correlates with lack of complete response to neoadjuvant therapy and diminished disease-free survival. This defect can be restored with HER-2 vaccinations in both DCIS and IBC. Correcting the anti-HER-2 Th1 response may have significant impact in improving response to HER-2 targeted therapies. Development of immune monitoring systems for anti-HER-2 Th1 to identify patients at risk for recurrence could be critical to improving outcomes, since the anti-HER-2 Th1 response can be restored by vaccination. Correction of the cellular immune response against HER-2 may prevent recurrence in high-risk patients with DCIS and IBC at risk of developing new or recurrent breast cancer.Fil: Nocera, Nadia F.. University of Pennsylvania; Estados UnidosFil: Lee, M. Catherine. H. Lee Moffitt Cancer Center; Estados UnidosFil: De La Cruz, Lucy M.. University of Pennsylvania; Estados UnidosFil: Rosemblit, Cinthia. University of Pennsylvania; Estados UnidosFil: Czerniecki, Brian J.. H. Lee Moffitt Cancer Center; Estados Unido

Oncodriver inhibition and CD4+ Th1 cytokines cooperate through Stat1 activation to induce tumor senescence and apoptosis in HER2+ and triple negative breast cancer: implications for combining immune and targeted therapies

In patients with HER2-expressing breast cancer many develop resistance to HER2 targeted therapies. We show that high and intermediate HER2-expressing cancer cell lines are driven toward apoptosis and tumor senescence when treated with either CD4+ Th1 cells, or Th1 cytokines TNF-α and IFN-γ, in a dose dependent manner. Depletion of HER2 activity by either siRNA or trastuzumab and pertuzumab, and subsequent treatment with either anti-HER2 Th1 cells or TNF-α and IFN-γ resulted in synergistic increased tumor senescence and apoptosis in cells both sensitive and cells resistant to trastuzumab which was inhibited by neutralizing anti-TNF-α and IFN-γ. Th1 cytokines induced minimal senescence or apoptosis in triple negative breast cancer cells (TNBC); however, inhibition of EGFR in combination with Th1 cytokines sensitized those cells causing both senescence and apoptosis. TNF-α and IFN-γ led to increased Stat1 phosphorylation through serine and tyrosine sites and a compensatory reduction in Stat3 activation. Single agent IFN-γ enhanced Stat1 phosphorylation on tyrosine 701 and similar effects were observed in combination with TNF-α and EGFR inhibition. These results demonstrate Th1 cytokines and antioncodriver blockade cooperate in causing tumor senescence and apoptosis in TNBC and HER2-expressing breast cancer, suggesting these combinations could be explored as non-cross-reactive therapy preventing recurrence in breast cancer.Fil: Rosemblit, Cinthia. H. Lee Moffitt Cancer Center; Estados Unidos. University of Pennsylvania; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Datta, Jashodeep. University of Pennsylvania; Estados UnidosFil: Lowenfeld, Lea. University of Pennsylvania; Estados UnidosFil: Xu, Shuwen. University of Pennsylvania; Estados UnidosFil: Basu, Amrita. H. Lee Moffitt Cancer Center; Estados UnidosFil: Kodumudi, Krithika. H. Lee Moffitt Cancer Center; Estados UnidosFil: Wiener, Doris. H. Lee Moffitt Cancer Center; Estados UnidosFil: Czerniecki, Brian J.. H. Lee Moffitt Cancer Center; Estados Unidos. University of Pennsylvania; Estados Unido

Progestins induce transcriptional activation of signal transducer and activator of transcription 3 (Stat3) via a Jak- and Src-dependent mechanism in breast cancer cells

Interactions between steroid hormone receptors and signal transducer and activator of transcription (Stat)-mediated signaling pathways have already been described. In the present study, we explored the capacity of progestins to modulate Stat3 transcriptional activation in an experimental model of hormonal carcinogenesis in which the synthetic progestin medroxyprogesterone acetate (MPA) induced mammary adenocarcinomas in BALB/c mice and in the human breast cancer cell line T47D. We found that C4HD epithelial cells, from the MPA-induced mammary tumor model, expressed Stat3 and that MPA treatment of C4HD cells up-regulated Stat3 protein expression. In addition, MPA induced rapid, nongenomic Stat3, Jak1, and Jak2 tyrosine phosphorylation in C4HD and T47D cells. MPA treatment of C4HD cells also resulted in rapid c-Src tyrosine phosphorylation. These effects were completely abolished by the progestin antagonist RU486. Abrogation of Jak1 and Jak2 activity by transient transfection of C4HD cells with dominant negative (DN) Jak1 or DN Jak2 vectors, or inhibition of Src activity by preincubation of cells with the Src family kinase inhibitor PP2, blocked the capacity of MPA to induce Stat3 phosphorylation. Treatment of C4HD cells with MPA induced Stat3 binding to DNA. In addition, MPA promoted strong Stat3 transcriptional activation in C4HD and T47D cells that was inhibited by RU486 and by blockage of Jak1, Jak2, and Src activities. To investigate the correlation between MPA-induced Stat3 activation and cell growth, C4HD cells were transiently transfected with a DN Stat3 expression vector, Stat3Y705-F, or with a constitutively activated Stat3 mutant, Stat3-C. While expression of Stat3Y705-F mutant had an inhibitory effect on MPA-induced growth of C4HD cells, transfection with the constitutively activated Stat3-C vector resulted in MPA-independent proliferation. Finally, we addressed the effect of targeting Stat3 in in vivo growth of C4HD breast tumors. Blockage of Stat3 activation by transfection of C4HD cells with the DN Stat3Y705-F expression vector significantly inhibited these cells' ability to form tumors in syngeneic mice. Our results have for the first time demonstrated that progestins are able to induce Stat3 transcriptional activation, which is in turn an obligatory requirement for progestin stimulation of both in vitro and in vivo breast cancer growth.Fil: Proietti Anastasi, Cecilia Jazmín. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Salatino, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Rosemblit, Cinthia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Carnevale, Romina Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Pecci, Adali. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Kornblihtt, Alberto Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Molinolo, Alfredo. National Institutes of Health; Estados UnidosFil: Frahm, Isabel. Sanatorio Mater Dei Hermanas de María de Schoenstatt; ArgentinaFil: Charreau, Eduardo Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Schillaci, Roxana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Elizalde, Patricia Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentin

Transcriptional regulation of oncogenic protein kinase Cε (PKCε) by STAT1 and Sp1 proteins

Overexpression of PKCε, a kinase associated with tumor aggressiveness and widely implicated in malignant transformation and metastasis, is a hallmark of multiple cancers, including mammary, prostate, and lung cancer. To characterize the mechanisms that control PKCε expression and its up-regulation in cancer, we cloned an ∼1.6-kb promoter segment of the human PKCε gene (PRKCE) that displays elevated transcriptional activity in cancer cells. A comprehensive deletional analysis established two regions rich in Sp1 and STAT1 sites located between -777 and-105 bp (region A) and-921 and-796 bp (region B), respectively, as responsible for the high transcriptional activity observed in cancer cells. A more detailed mutagenesis analysis followed by EMSA and ChIP identified Sp1 sites in positions -668/-659 and-269/-247 as well as STAT1 sites in positions -880/-869 and- 793/-782 as the elements responsible for elevated promoter activity in breast cancer cells relative to normal mammary epithelial cells. RNAi silencing of Sp1 and STAT1 in breast cancer cells reduced PKCε mRNA and protein expression, as well as PRKCE promoter activity. Moreover, a strong correlation was found between PKCε and phospho-Ser-727 (active) STAT1 levels in breast cancer cells. Our results may have significant implications for the development of approaches to target PKCε and its effectors in cancer therapeutics.Centro de Investigaciones Inmunológicas Básicas y AplicadasFacultad de Ciencias Médica

p42/p44 MAPK-mediated Stat3 Ser727 phosphorylation is required for progestin-induced full activation of Stat3 and breast cancer growth

Stat3 is a signaling node for multiple oncogenic pathways and is therefore frequently active in breast cancer. As experimental and clinical evidence reveals that progestins are key players in controlling mammary gland tumorigenesis, we studied Stat3 participation in this event. We have previously shown that progestins induce Stat3Tyr705 phosphorylation and its transcriptional activation in breast cancer cells. In this study, we demonstrate that progestins also induce Stat3 phosphorylation at Ser727 residue, which occurs via activation of c-Src/p42/p44 MAPK pathways in murine progestin-dependent C4HD cells and in T-47D cells. Expression of a Stat3S727A vector, which carries a serine-to-alanine substitution at codon 727, shows that Stat3Ser727 phosphorylation is required for full transcriptional activation of cyclin D1 gene expression by progestins and for in vivo Stat3 recruitment on cyclin D1 promoter. Transfection of Stat3S727A in murine and human breast cancer cells abolished progestin-induced in vitro and in vivo growth. Moreover, we found a positive correlation between progesterone receptor expression and nuclear localization of Stat3Ser727 phosphorylation in breast cancer biopsies. These data highlight Stat3 phosphorylation in Ser727 residue as a nongenomic action by progestins, necessary to promote breast cancer growth.Fil: Tkach, Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Rosemblit, Cinthia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Rivas, Martin Alfredo. Vall d; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Proietti Anastasi, Cecilia Jazmín. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Díaz Flaqué, María Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Mercogliano, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Beguelin, Wendy. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Maronna, Esteban. Sanatorio Mater Dei; ArgentinaFil: Guzman, Pablo. Universidad de la Frontera. Facultad de Medicina; ChileFil: Gercovich, Felipe G.. Instituto Oncológico Henry Moore; ArgentinaFil: Gil Deza, Ernesto. Instituto Oncológico Henry Moore; ArgentinaFil: Elizalde, Patricia Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); ArgentinaFil: Schillaci, Roxana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); Argentin

Inhibition diminishes cell viability via PKC alpha (PKCa) in thyroid cancer cells

Thyroid carcinoma (TC) is the most common endocrine neoplasia.Its incidence has increased in the last 40 years worldwide. It comprises a group of tumors of different lineage and biological behavior.About half of TC are driven by an acquired activating mutation inthe BRAF oncogene. While targeted therapies have improved outcomes in melanoma patients, most TC patients become resistant orrecur suggesting that new or additive non-cross-reactive therapiesare needed. We have previously shown that PKCa mediates TSHand thyroid hormones proliferative effects in TC. Recent evidenceindicates that together PKCa overexpression and BRAF mutationshould contribute to tumorigenesis and resistance to anticancertherapies. We found that by inhibiting BRAF expression with RNAi inanaplastic TC cells with BRAF mutation, PKCa expression decreases as well, suggesting that the latter is found downstream of BRAF.Furthermore, a decrease in the expression of the cell proliferationmarker PCNA was observed in BRAF-depleted cells by westernblot analysis. Also, TC cells were sensitive to increasing doses ofthe BRAF inhibitor widely used in the clinic vemurafenib/PLX4032in a dose-dependent manner (p<0.0001) by Cell Titer Blue (CTB)assay. To begin to study the combined inhibition of PKC and BRAF,CTB assays were performed with increasing doses of vemurafenibin presence or absence of the PKC inhibitor GF109203X at selective concentrations in follicular TC cells carrying BRAF mutation. Weconfirmed the dose-dependency of vemurafenib and found that thecombination leads to a significant decrease in cell viability (p<0.5).Our results establish that the effective dual PKCa and BRAF blockade can significantly drive tumor proliferation inhibition. The results obtained could provide new therapeutic targets and alternatives tothe treatments currently used for this disease. Despite its increasingincidence and mortality in many cases, TC constitutes a very poorlystudied area in our country.Fil: Campos Haedo, Mateo Nicolas. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Díaz Flaqué, María Celeste. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Díaz Albuja, Johanna Abigail. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Perona, Marina. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Debernardi, Maria Mercedes. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Cayrol, Maria Florencia. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Barreiro Arcos, María Laura. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Sterle, Helena Andrea. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Juvenal, Guillermo Juan. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cremaschi, Graciela Alicia. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Rosemblit, Cinthia. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaLXV Reunión Anual de la Sociedad Argentina de Investigación Clínica; LXVIII Reunión Anual de la Sociedad Argentina de Inmunología y Reunión Anual de la Sociedad Argentina de FisiologíaArgentinaSociedad Argentina de Investigación ClínicaSociedad Argentina de FisiologíaSociedad Argentina de Inmunologí

Transcriptional regulation of oncogenic protein kinase Cε (PKCε) by STAT1 and Sp1 proteins

Overexpression of PKCε, a kinase associated with tumor aggressiveness and widely implicated in malignant transformation and metastasis, is a hallmark of multiple cancers, including mammary, prostate, and lung cancer. To characterize the mechanisms that control PKCε expression and its up-regulation in cancer, we cloned an ∼1.6-kb promoter segment of the human PKCε gene (PRKCE) that displays elevated transcriptional activity in cancer cells. A comprehensive deletional analysis established two regions rich in Sp1 and STAT1 sites located between -777 and-105 bp (region A) and-921 and-796 bp (region B), respectively, as responsible for the high transcriptional activity observed in cancer cells. A more detailed mutagenesis analysis followed by EMSA and ChIP identified Sp1 sites in positions -668/-659 and-269/-247 as well as STAT1 sites in positions -880/-869 and- 793/-782 as the elements responsible for elevated promoter activity in breast cancer cells relative to normal mammary epithelial cells. RNAi silencing of Sp1 and STAT1 in breast cancer cells reduced PKCε mRNA and protein expression, as well as PRKCE promoter activity. Moreover, a strong correlation was found between PKCε and phospho-Ser-727 (active) STAT1 levels in breast cancer cells. Our results may have significant implications for the development of approaches to target PKCε and its effectors in cancer therapeutics.Centro de Investigaciones Inmunológicas Básicas y AplicadasFacultad de Ciencias Médica

Effect of human gonadotropins on spermiation and androgen biosynthesis in the testis of the toad Bufo arenarum (Amphibia, Anura)

This paper analyzes, in the toad Bufo arenarum, the effect on spermiation and androgen secretion of two human recombinant gonadotropins, human recombinant LH (hrLH) and human recombinant FSH (hrFSH) as well as the well-known spermiation-inducing hormone, human chorionic gonadotropin (hCG). For this purpose, testes were incubated with different concentrations of hrLH (0.01–2.5 µg/ml) and hrFSH (0.05–5 µg/ml), and results were compared with those obtained with 2.5 µg/ml hCG. Spermiation was most efficiently stimulated by hrFSH, which elicited a higher response than either hrLH or hCG. Both hrFSH and hrLH produced a bell-shaped dose–response curve, with a 50% inhibition on spermiation at a concentration twice higher than that necessary to get the highest response. However, none of the gonadotropins yielded a biphasic response on androgen secretion, hrLH producing the highest response at a concentration that evoked a 70% inhibition in the spermiation test. Regarding steroidogenesis, hrLH and hrFSH were more active than hCG. Taken together, the results described in this paper suggest that, in B. arenarum, spermiation and androgen secretion are mediated by different receptors. After comparing the effects of recombinant hormones, we conclude that hrFSH has a greater effect on spermiation than hCG or hrLH.Fil: Pozzi, Andrea Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Rosemblit, Cinthia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Ceballos, Nora Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentin

Abstract 1333: CD4 Th1 cytokines and HER-2/HER-3 blockade induces tumor apoptosis in breast cancer

Abstract Background: The therapeutic benefit of blocking HER2/HER3 signaling in breast cancer (BC) has been demonstrated by several studies. We have previously shown that the pleiotropic T-helper type 1 (Th1) cytokines IFN-γ and TNF-α induce senescence in BC cells and that all BC cell lines tested express IFN-γ and TNF-α receptors by western blot analysis. We have also demonstrated an inverse correlation between the HER2 expression level and the senescence induced by the treatment with both cytokines. Moreover, simultaneous HER-2/HER-3 blockade significantly enhanced cytokine-induced senescence. Here, we studied whether these Th1 cytokines induce apoptosis of HER-2 expressing BC cells and assessed the impact of IFN-γ and TNF-α with simultaneous HER-2 and HER-3 blockade on permanent tumor abrogation. Results: To determine the Th1-mediated effects on HER2high (SK-BR-3, BT-474), HER2intermediate (MCF-7, T-47D), and HER2low (MDA-MB-231) human BC cell lines in vitro, we performed co-culture of increasing number of HER2 Class II peptide-specific CD4+ T-cells (generated by priming CD4+ T cells with HER2 peptide loaded type-1 polarized DCs) with BC cells using a transwell culture system. This resulted in a cell number-dependent apoptosis of SK-BR-3 and MCF-7, but not MDA-MB-231 cells compared with CD4+ T cells primed either with immature dendritic cells (DC) or mature DC plus irrelevant (Class II BRAF) peptide. In addition, SK-BR-3 cells incubated with supernatants from the CD4+ T cells-immature DC or mature DC co-culture demonstrated similar results. Compared with controls, HER2-specific Th1 cells generated a 25-fold increase in SK-BR-3 apoptosis by DAPI staining. Neutralizing antibodies against IFN-γ and TNF-α significantly reduced apoptosis induction. Also, IFN-γ and TNF-α treatment resulted in significant apoptosis of SK-BR-3 and MCF-7, but not MDA-MB-231 cells. However, MDA-MB-231 cells transfected with a wild type HER2 plasmid, were highly susceptible to cytokine-induced apoptosis. Treatment of HER-2-depleted cells (by RNAi) with IFN-γ and TNF-α resulted in an increased apoptotic phenotype. Although the combined treatment of IFN-γ and TNF-α in HER3-depleted cells did not enhanced the apoptosis, the double knock down with HER2 and HER3 RNAi strongly increased apoptosis induction as observed by western blot analysis of active caspase-3 and flow cytometric analysis of Anexin V-PI staining. Interestingly, the double depleted cells treated with IFN-γ alone evidenced slightly higher cleaved caspase-3 levels than TNF-α alone but the combined treatment with both cytokines had a strong synergistic effect. Conclusions: Our results establish a role for IFN-γ and TNF-α in inducing tumor apoptosis in BC. An effective CD4 Th1 response, combined with HER-2 and HER-3 blockade can significantly drive tumor apoptosis that can be explored as treatment to effectively eliminate residual BC cells and prevent recurrence. Citation Format: Cinthia Rosemblit, Jashodeep Datta, Erik Berk, Brian J. Czerniecki. CD4 Th1 cytokines and HER-2/HER-3 blockade induces tumor apoptosis in breast cancer. [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 1333. doi:10.1158/1538-7445.AM2015-133

Rac signaling in breast cancer: A tale of GEFs and GAPs

Rac GTPases, small G-proteins widely implicated in tumorigenesis and metastasis, transduce signals from tyrosine-kinase, G-protein-coupled receptors (GPCRs), and integrins, and control a number of essential cellular functions including motility, adhesion, and proliferation. Deregulation of Rac signaling in cancer is generally a consequence of enhanced upstream inputs from tyrosine-kinase receptors, PI3K or Guanine nucleotide Exchange Factors (GEFs), or reduced Rac inactivation by GTPase Activating Proteins (GAPs). In breast cancer cells Rac1 is a downstream effector of ErbB receptors and mediates migratory responses by ErbB1/EGFR ligands such as EGF or TGFα and ErbB3 ligands such as heregulins. Recent advances in the field led to the identification of the Rac-GEF P-Rex1 as an essential mediator of Rac1 responses in breast cancer cells. P-Rex1 is activated by the PI3K product PIP3 and Gβγ subunits, and integrates signals from ErbB receptors and GPCRs. Most notably, P-Rex1 is highly overexpressed in human luminal breast tumors, particularly those expressing ErbB2 and estrogen receptor (ER). The P-Rex1/Rac signaling pathway may represent an attractive target for breast cancer therapy.Susan G. Komen for the Cure (M.G.K.)National Institutes of Health (NIH)Depto. de Bioquímica y Biología MolecularFac. de FarmaciaTRUEpu