BackgroundExtracellular human sulfatases modulate growth factor signaling by alteration of the heparin/heparan sulfate proteoglycan (HSPG) 6-O-sulfation state. HSPGs bind to numerous growth factor ligands including fibroblast growth factors (FGF), epidermal growth factors (EGF), and vascular endothelial growth factors (VEGF), and are critically important in the context of cancer cell growth, invasion, and metastasis. We hypothesized that sulfatase activity in the tumor microenvironment would regulate tumor growth in vivo.MethodsWe established a model of stable expression of sulfatases in the human breast cancer cell line MDA-MB-231 and purified recombinant human Sulfatase 2 (rhSulf2) for exogenous administration. In vitro studies were performed to measure effects on breast cancer cell invasion and proliferation, and groups were statistically compared using Student's t-test. The effects of hSulf2 on tumor progression were tested using in vivo xenografts with two methods. First, MDA-MB-231 cells stably expressing hSulf1, hSulf2, or both hSulf1/hSulf2 were grown as xenografts and the resulting tumor growth and vascularization was compared to controls. Secondly, wild type MDA-MB-231 xenografts were treated by short-term intratumoral injection with rhSulf2 or vehicle during tumor growth. Ultrasound analysis was also used to complement caliper measurement to monitor tumor growth. In vivo studies were statistically analyzed using Student's t test.ResultsIn vitro, stable expression of hSulf2 or administration of rhSulf2 in breast cancer cells decreased cell proliferation and invasion, corresponding to an inhibition of ERK activation. Stable expression of the sulfatases in xenografts significantly suppressed tumor growth, with complete regression of tumors expressing both hSulf1 and hSulf2 and significantly smaller tumor volumes in groups expressing hSulf1 or hSulf2 compared to control xenografts. Despite significant suppression of tumor volume, sulfatases did not affect vascular density within the tumors. By contrast, transient exogenous treatment of MDA-MB-231 xenografts with rhSulf2 was not sufficient to inhibit or reverse tumor growth.ConclusionThese data indicate that in vivo progression of human breast cancer xenografts can be inhibited with sulfatase expression, and therapeutic effect requires constant delivery at the tumor site. Our results support a direct effect of sulfatases on tumor growth or invasion, rather than an effect in the stromal compartment.

BackgroundComplement C2 deficiency is the most common genetically determined complete complement deficiency and is associated with a number of diseases. Most prominent are the associations with recurrent serious infections in young children and the development of systemic lupus erythematosus (SLE) in adults. The links with these diseases reflect the important role complement C2 plays in both innate immunity and immune tolerance. Infusions with normal fresh frozen plasma for the treatment of associated disease have demonstrated therapeutic effects but so far protein replacement therapy has not been evaluated.ResultsHuman complement C2 was cloned and expressed in a mammalian cell line. The purity of recombinant human C2 (rhC2) was greater than 95% and it was characterized for stability and activity. It was sensitive to C1s cleavage and restored classical complement pathway activity in C2-deficient serum both in a complement activation ELISA and a hemolytic assay. Furthermore, rhC2 could increase C3 fragment deposition on the human pathogen Streptococcus pneumoniae in C2-deficient serum to levels equal to those with normal serum.ConclusionsTaken together these data suggest that recombinant human C2 can restore classical complement pathway activity and may serve as a potential therapeutic for recurring bacterial infections or SLE in C2-deficient patients.

RON is a receptor tyrosine kinase of the MET family. Stimulation by its ligand, Macrophage Stimulating Protein (MSP), activates a signaling cascade leading to cell growth, migration, invasion and resistance to apoptosis. In animal models, RON overexpression in breast and lung results in tumor growth and metastasis. RON receptor activation in animal models also play a role in tumor-host interactions such as osteolytic bone destruction and tumor associated macrophage infiltration. RON overexpression has been demonstrated in several solid tumors including pancreatic, breast, ovarian and colon. RON overexpression is correlated with disease progression and shorter survival in ovarian and colon cancer. Several isoforms of RON have been reported, including a potentially oncogenic form, RON Δ160 in CRC. Given the strong evidence for the involvement of RON in numerous aspects of tumor biology, investigating an anti-RON antibody as cancer therapy is warranted. We have identified and characterized a panel of antagonistic murine anti-human RON antibodies. Humanization of two antibodies resulted in Superhumanized™ anti-RON antibodies that are capable of inhibiting MSP dependent RON downstream signaling, cell migration and invasion in vitro. The anti-RON antibodies have subnanomolar binding affinity to wildtype RON and RON Δ160 receptors. The lead antibody is capable of internalizing and degrading the receptor in vitro and in vivo. The antibodies are capable of inhibiting growth of engineered murine models that are driven by wildtype or RON Δ160 receptor, as well as traditional human cancer xenografts. Given the complex role of RON in tumor biology, identification of response biomarkers is crucial for identifying the patient populations most likely to benefit from treatment. A multi-gene biomarker potentially predictive of tumor response to RON antibody, the RON pathway index, was tested and validated using a panel of human cancer cell line xenografts. Current results demonstrate a statistically significant correlation between the degree of tumor growth inhibition by anti-RON antibody treatment and RON pathway index value. Thus, we have identified a biomarker of tumor response to anti-RON antibody that can potentially help us identify tumor types or tumor subtypes of interest in the clinic. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 644. doi:10.1158/1538-7445.AM2011-644

Human complement component C2 is a critical factor of the classical complement pathway. Here we provide a method for the production of recombinant human C2 (rhC2) protein for research purposes. The human complement component C2 (hC2) is cloned from a human cDNA library by polymerase chain reaction and inserted in a mammalian expression vector (Martini et al., BMC Immunol 11:43, 2010). Transient transfection is utilized to express hC2 in a mammalian cell line, and the expressed C2 is harvested from the conditioned media. rhC2 is purified from the conditioned media by sequential steps of cation exchange and affinity column chromatography. The purified hC2 is characterized for protein purity, stability, and enzymatic activity. The recombinant hC2 activity is tested in a complement activation ELISA assay that measures classical, alternative, and lectin complement pathway activity in C2-depleted serum.