Inhibition of tumor progression during allergic airway inflammation in a murine model: significant role of TGF-β

Introduction

TGF-β is an important mediator of pulmonary allergic inflammation, and it has been recently reported to be a potential inhibitor of lung tumor progression. The correlation between cancer and allergic inflammatory diseases remains controversial. Thus, the aim of the present study was to evaluate the effects of pulmonary allergic inflammation and in particular the role of TGF-β on cancer progression.

Methods

Cancer cells were implanted in a BALB/c mice model of allergic airway inflammation, and tumor growth was measured. Apoptosis was evaluated by TUNEL assay, and TGF-β was measured by ELISA. Expression of proliferating cell nuclear antigen, TGF-β, TGF-β receptors I and II, phospho-Smad2 and phospho-Smad4 was evaluated by immunohistochemistry and quantified using digital pathology. The effect of a TGF-β activity inhibitor and recombinant TGF-β on tumor growth was analyzed. The effect of exogenous TGF-β on cell proliferation and apoptosis was evaluated in vitro.

Results

Mice with allergic airway inflammation exhibited decreased tumor volumes due to cell proliferation inhibition and increased apoptosis. TGF-β was increased in the sera and tumor tissues of allergic mice. TGF-β activity inhibition increased tumor progression in allergic mice by enhancing proliferation and decreasing apoptosis of tumor cells. The administration of TGF-β resulted in reduced tumor growth.

Conclusion

This study is the first to establish an inverse relationship between allergic airway inflammation and tumor progression. This effect appears to be mediated by TGF-β, which is overexpressed in tumor cells during pulmonary allergic inflammation. This study indicates that TGF-β is a potential target for antitumor therapy.

Electronic supplementary material

The online version of this article (doi:10.1007/s00262-015-1722-4) contains supplementary material, which is available to authorized users.

Contribution of either YY1 or BclXL-induced inhibition by the NO-donor DETANONOate in the reversal of drug resistance, both in vitro and in vivo. YY1 and BclXL are overexpressed in prostate cancer

Nitric oxide (NO) donors have been shown to activate or inhibit constitutively-activated survival/anti-apoptotic pathways, such as NF-κB, in cancer cells. We report here that treatment of drug-resistant human prostate carcinoma cell lines with high levels (500-1000 μM) of the NO-donor DETANONOate sensitized the resistant tumor cells to apoptosis by CDDP and the combination was synergistic. We hypothesized that DETANONOate inhibits previously identified NF-κB-regulated resistant factors such as Yin Yang 1 (YY1) and Bcl-2/BclXL. Lysates from tumor cells treated with DETANONOate showed inhibition of YY1 and BclXL expressions. Transfection with either YY1 or BclXL siRNA resulted in the inhibition of both YY1 and BclXL expressions and sensitized the cells to CDDP apoptosis. Mice bearing PC-3 tumor xenografts and treated with the combination of DETANONOate and CDDP resulted in significant inhibition of tumor growth; treatment with single agent alone did not have any effect on tumor growth. Analysis of patients TMA tissues with prostatic cancer revealed higher expression of both YY1 and BclXL as a function of tumor grades and their levels were directly correlated. Thus, both YY1 and BclXL are potential prognostic biomarkers. Overall, the above findings suggest that one mechanism of DETANONOate-induced sensitization of resistant tumor cells to CDDP correlated with the inhibition of NF-κB and its targets YY1 and BclXL. The examination of the combination of NO donors and cytotoxic therapy in the treatment of resistant prostate cancer may be warranted.

Abstract 3374: BRAF and NRAS mutations in melanoma regulate the phosphorylation and inactivation of RKIP, the metastasis suppressor and immune surveillance cancer gene product

The Raf Kinase Inhibitor Protein (RKIP) is a member of the phosphatidylethanolamine binding protein family (PEBP). RKIP binds to Raf-1 and prevents the activation of the ERK 1/2 cascade. RKIP expression is diminished in many primary cancers and is absent in many metastases. RKIP overexpression inhibits experimental metastases, hence, termed a metastasis suppressor. In addition, overexpression of RKIP reverses tumor cell resistance to drug-induced apoptosis, hence, termed an immune surveillance cancer gene product. Phosphorylation of RKIP (pRKIP) at Ser 153 by PKCs dissociates RKIP from Raf-1 (inactivating RKIP) and pRKIP binds to G-protein coupled receptor kinase 2 (GRK2, a kinase that inhibits G-protein coupled receptors (GPCRs) and resulting in the inhibition of GRK2 activity and stimulation of the ERK 1/2 activity. Over 90% of melanoma express oncogene mutations in BRAF and also express mutations in NRAS. Most of the transforming activity of these mutations results from the activation of MAPK. The roles of such mutations in the regulation of oncogenes involved in metastasis and resistance are not clear. The objective of this study was to initiate investigations on the roles of above mutations on the expression of RKIP and inactive pRKIP. We hypothesized that BRAF and NRAS mutations, through their activation of PKCs, will result in the phosphorylation and inactivation of RKIP and potentiation of ERK 1/2 activation, metastasis and drug resistance. In this study, we have examined a large panel of melanoma cell lines with no mutations and with BRAF and/or NRAS mutations using a Tissue microarray technology. The expression of both RKIP and pRKIP was examined and the evaluation of protein expression was performed by IHC and analyzed by blinded observers under light microscopy. While anti-RKIP antibody detects both RKIP and pRKIP, anti-pRKIP was specific for pRKIP. The mean intensities for the expression of each protein were determined using the software Image-ProPlus 6.3. In brief, five random fields of each cell line were evaluated at 400-magnification. From the IHC staining, general density expressions of each protein in the cell lines were measured in pixels/200 μm2. The data revealed that the majority (75%) of RKIP expression was in its phosphorylated form in cell lines with BRAF and NRAS mutations. These studies suggest that in melanoma cell lines with mutations, GRK2 is inactivated through its association with pRKIP and, thus, maintaining the activating signals mediated by GPCRs. Further, pRKIP expression may potentiate the metastatic potential and drug resistance. We propose that selective inhibitors of PKCs may elevate the expression of RKIP and result in the inhibition of the metastatic potential as well as in the sensitization of the tumor cells to subtoxic therapeutic drugs. These studies are currently being examined in our laboratories.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3374.

Abstract 2242: Correlation between the overexpression of the metastasis-inducer transcription factors Snail and Yin Yang 1 and BRAF mutations in a large panel of melanoma cell lines

Over 90% of melanoma express oncogenic mutations in BRAF at the V600E position. Most of the transforming activity of the BRAF V600E is thought to result through the activation of the mitogen-activated protein kinase (MAPK) pathway. The discovery of BRAF mutations has alluded to targeted therapy. The role of BRAF mutations in the regulation of oncogenes involved in metastasis has not been fully explored. The metastasis-inducer gene product Snail regulates the EMT phenotype in the metastasis cascade. Snail is under the transcription regulation of NF-κB and is constitutively activated in tumors. Noteworthy, Snail negatively regulates the expression of the metastasis suppressor gene product, RKIP. Likewise, Yin-Yang 1 (YY1) regulates Snail and is downstream of NF-κB. The regulation of the YY1, Snail and RKIP expressions by BRAF mutations has been investigated. We hypothesized that the expression levels of YY1 will be correlated with the expression levels of Snail and inversely correlated with the expression levels of RKIP in melanoma and that the BRAF mutations may enhance these relationships due to its activation of the NF-κB pathway. In this study, we have analyzed a panel of 32 melanoma cell lines with BRAF mutations using a tissue microarray technology. The gene products YY1, Snail and RKIP were examined and, in addition, the inactive phosphorylated form of RKIP was also evaluated. Protein expressions were assessed by immunohistochemistry and were then analyzed by blinded observers under light microscopy. The mean intensities for the expression of each gene product were determined by using the software Image-ProPlus 6.3. The data revealed the following: (1) There was a correlation between the levels of YY1 and Snail expressions in the cell lines and (2) There was an inverse correlation between the levels of RKIP and both Snail and YY1 levels. The relationship between active RKIP and inactive phospho-RKIP demonstrated that the majority was in the inactivated phosphorylated form. These findings demonstrate that melanoma with BRAF mutations, which activate the NF-κB pathway, resulted in the upregulation of the metastasis inducer gene products YY1 and Snail and, consequently, inhibition and/or inactivation of the metastasis-suppressor RKIP. Thus, these studies revealed that BRAF mutations regulate the EMT metastatic phenotype through the activation of NF-κB, Snail, and YY1, while inhibiting and/or inhibiting the metastasis suppressor RKIP. We suggest that Snail, YY1, and RKIP are potential targets for therapeutic intervention in the inhibition of metastasis. In addition, we have shown that these same gene products regulate tumor cell resistance to cytotoxic therapeutics and, thereby, targeted therapeutic interventions may exert dual roles in the inhibition of metastasis and reversal of resistance.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2242.