Inflammation within the tumor microenvironment correlates with increased invasiveness and poor prognosis in many types of cancer, including breast cancer. The cytokines interleukin-6 (IL-6), tumor necrosis factor alpha (TNFalpha) and interleukin-1 beta (IL-1beta) are critical mediators of the inflammatory response. Numerous studies have also linked these cytokines to breast cancer progression. As a result, the mechanisms by which these cytokines promote breast cancer have been recently explored using both in vitro and in vivo models. The results from these studies have led to speculation regarding the possible usefulness of targeting these cytokines in breast cancer patients. This review summarizes the most recent studies pertaining to the mechanisms by which proinflammatory cytokines promote breast cancer. Furthermore, the possibilities of targeting these inflammatory mediators in breast cancer patients using inhibitors that are currently being used in the clinic for other inflammatory conditions are discussed. Understanding both the mechanisms by which inflammatory mediators promote breast cancer and the effectiveness of anti-inflammatory drugs in treating breast cancer will lead to novel therapeutic regimens to treat this devastating disease.

The recent discovery of a novel, membrane localized progestin receptor (mPR) unrelated to the classical progesterone receptor (PR) in fishes and its subsequent identification in mammals suggests a potential mediator of non-traditional progestin actions, particularly in tissues where PR is absent. While early studies on mPR focused on final oocyte maturation in fishes, more current studies have examined mPRs in multiple mammalian systems in both reproductive and nonreproductive tissues as well as in diseased tissues. Here we review the current data on mPR in mammalian systems including male and female reproductive tracts, liver, neuroendocrine tissues, the immune system and breast and ovarian cancer. We also provide new data demonstrating mPR expression in the RAW 264.7 immune cell line and bone marrow-derived macrophages as well as mPR expression and downstream gene regulation in ovarian cancer cells.

Aberrant activation of fibroblast growth factor receptors (FGFRs) contributes to breast cancer growth, progression and therapeutic resistance. Due to the complex nature of the FGF/FGFR axis, and the numerous effects of FGFR activation on tumor cells and the surrounding microenvironment, the specific mechanisms through which aberrant FGFR activity contributes to breast cancer are not completely understood. We show here that FGFR activation induces accumulation of hyaluronan (HA) within the extracellular matrix (ECM) and that blocking HA synthesis decreases proliferation, migration and therapeutic resistance. Furthermore, FGFR-mediated HA accumulation requires activation of the signal transducer and activator of transcription 3 (STAT3) pathway, which regulates expression of hyaluronan synthase 2 (HAS2) and subsequent HA synthesis. Using a novel in vivo model of FGFR-dependent tumor growth, we demonstrate that STAT3 inhibition decreases both FGFR-driven tumor growth and HA levels within the tumor. Finally, our results suggest that combinatorial therapies inhibiting both FGFR activity and HA synthesis is more effective than targeting either pathway alone and may be a relevant therapeutic approach for breast cancers associated with high levels of FGFR activity. In conclusion, these studies indicate a novel targetable mechanism through which FGFR activation in breast cancer cells induces a pro-tumorigenic microenvironment.

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S u m m a r ySynthetic peptides corresponding to sequences of HLA class I molecules have inhibitory effects on T cell function. The peptides investigated in this study have sequences corresponding to the relatively conserved region of the or1 helix of HLA class I molecules that overlaps the "public epitope" Bw4/Bw6. These HLA-derived peptides exhibit inhibitory effects on T lymphocytes and have beneficial effects on the survival ofallogeneic organ transplants in mice and rats. Peptides corresponding to the Bw4a epitope appear most potent as they inhibit the differentiation of T cell precursors into mature cytotoxic T lymphocytes (CTL) and target cell lysis by established CTL lines and clones. To elucidate the mechanism through which these peptides mediate their inhibitory effect on T lymphocytes, peptide binding proteins were isolated from T cell lysates. We show that the inhibitory Bw4a peptide binds two members of the heat-shock protein (HSP) 70 family, constitutively expressed HSC70 and heat-inducible HSP70. Peptide binding to HSC/HSP70 is sequence specific and follows the rules defined by the HSC70 binding motif. Most intriguing, however, is the strict correlation of peptide binding to HSC/ HSP70 and the functional effects such that only inhibitory peptides bind to HSC70 and HSP70 whereas noninhibitory peptides do not bind. This correlation suggests that small molecular weight HLA-derived peptides may modulate T cell responses by directly interacting with HSPs. In contrast to numerous reports of HSP70 expression at the surface of antigen-presenting cells and some tumor cells, we find no evidence that HSC/HSP70 are expressed at the surface of the affected T cells. Therefore, we believe that the peptides' immunomodulatory effects are not mediated through a signaling event initiated by interaction of peptide with surface HSP, but favor a model similar to the action of other immunomodulatory compounds, FK506 and cyclosporin A, with a role for HSC/HSP70 similar to that for immunophilins, FKBPs and CyP40. T cell responses triggered by polymorphic differences between MHC class I molecules of recipient and donor tissue are the major barrier to successful transplant engraftment. Despite advances in immunosuppressive therapy, acute graft rejection and failure to achieve long-lasting graft acceptance still persist. Thus, the ultimate goal in transplant biology is to achieve long-lasting, antigen-specific unresponsiveness (immunological tolerance). The beneficial effect of blood transfusion on the survival of organ allografts has been recognized for years (1-3). Although the mechanisms underlying the enhancing effect of blood transfusion are undoubtedly complex, the contribution of soluble HLA class I molecules to induce nonresponsiveness to some allografts is well documented (2, 4, 5). However, studies using soluble HLA have been hindered by the difficulties in purifying sufficient quantities of material. We and others began to investigate the immunomodulatory activities of soluble HLA using synthetic peptides correspo...

SummaryFibroblast growth factor receptor 1 (FGFR1) is an oncoprotein with known involvement in mammary tumorigenesis. To understand how FGFR1 signaling promotes mammary tumorigenesis, an inducible FGFR1 (iFGFR1) system was created previously. Previous studies have demonstrated that upon iFGFR1 activation in vivo, the epidermal growth factor (EGF) ligands amphiregulin (AREG) and epiregulin (EREG) are upregulated. Both AREG and EREG interact with the EGF receptor (EGFR). Here, we investigated whether the FGFR1-induced increase in AREG and EREG expression might coordinately increase EGFR signaling to promote mammary tumorigenesis. Treatment of mouse mammary epithelial cells with either AREG or EREG conferred a greater migratory potential, increased cellular proliferation and increased extracellular regulated kinase 1/2 (ERK1/2) activation. These effects could be blocked with the EGFR-specific inhibitor erlotinib, suggesting that they are EGFR-dependent. In transgenic mice with iFGFR1 under the control of the mouse mammary tumor virus (MMTV) promoter, iFGFR1 activation also led to increased mammary epithelial cell proliferation that was inhibited with erlotinib. Taken together, these data suggest that AREG and EREG mediate tumorigenic phenotypes by activating EGFR signaling, and that the oncogenic potential of FGFR1 requires EGFR activation to promote mammary tumorigenesis.

<p>PDF file - 45K, Supplemental Figure 3. HC-11 or HC-11/R1 cells were injected into the mammary fat pads of Balb/c mice. Mice were palpated to determine the % tumor free.</p>