Franz Paul Armbruster

Characterization of a rat model with site-specific bone metastasis induced by MDA-MB-231 breast cancer cells and its application to the effects of an antibody against bone sialoprotein

Metastasis into the skeleton is a serious complication of certain neoplastic diseases such as breast, prostate and lung cancer, but the reasons for this osteotropism are poorly understood. Our aim was to establish a physiologically relevant animal model that is characterized by osteolytic lesions confined to the hind leg of nude rats. For this purpose, we injected 1×105 MDA‐MB‐231 human breast cancer cells transfected with GFP into the superficial epigastric artery, which is an anastomosing vessel between the femoral and iliac arteries. As assessed with the aid of X‐rays, computed tomography and immunohistochemisty, osteolytic lesions occurred exclusively in the femur, tibia and fibula of the animals. The tumor take rate was 93% in a series of 96 rats and the increase in lesion size was observed up to 110 days after tumor cell inoculation. When applying this animal model to the effects of an antibody against bone sialoprotein (BSP), a significantly reduced osteolytic lesion size was observed after preincubation of cells (2 hr, 600 μg/ml anti‐BSP) prior to intra‐arterial tumor cell injection resulting in 19 T/C% at day 60 after tumor implantation (p < 0.05). In addition, the osteolytic lesion size was also significantly reduced after s.c. treatment of the animals with the antibody (20 mg/kg anti‐BSPx3 within 5 days after tumor implantation), resulting in 30 T/C% at day 60 after tumor cell implantation (p < 0.05). In conclusion, the novel rat model for site‐specific osteolytic lesions provides in vivo evidence that preincubation of MDA‐MB‐231GFP cells and treatment of rats after tumor implantation with an antibody against BSP significantly reduces the size of lytic lesions in bone.

Relaxin as an Additional Protective Substance in Preserving and Reperfusion Solution for Liver Transplantation, Shown in a Model of Isolated Perfused Rat Liver

Abstract: Reperfusion injury is a problem in organ transplantation. Relaxin causes vessel dilation and inhibition of platelet and mast cell activation. The study investigates the protective effect of relaxin on liver tissue against cell damage during organ preservation and reperfusion. Liver transplantation was simulated in a model of isolated perfused rat liver. Relaxin was applicated during reperfusion and/or preservation. To quantify cell damage, we examined the perfusate for malonyldialdehyde (MDA) and myeloperoxidase activity (MPO), and liver tissue underwent immunohistochemical study. Relaxin as an additional substance in preserving/reperfusion solution decreases MPO and MDA levels in the perfusate and immunohistochemical study. Relaxin seems to have a protective effect against cell damage in ischemia and reperfusion injury.

Relaxin as a protective substance in the preserving solution for liver transplantation: spectrophotometric in vivo imaging of local oxygen supply in an isolated perfused rat liver model.

Ischemia reperfusion injury (IRI) is a problem in organ transplantation. Relaxin is known to have a protective effect against liver injury caused by IRI. Using a model of isolated perfused rat liver, the local oxygen supply in liver tissue was investigated by spectrophotometric in vivo imaging and compared to the protective effect of relaxin shown by immunohistochemical measurement of myeloperoxidase and malonyldialdehyde activities as determinants of oxidative stress. In relaxin‐treated liver tissue, spectrophotometry showed a better oxygen supply and decreased myeloperoxidase and malonyldialdehyde activities. Our data suggest that relaxin can influence the oxygen distribution in liver tissue and reduce cell damage caused by IRI.

Thymic Peptides Differentially Modulate Human Hair Follicle Growth

Abbreviations: HF, hair follicle; IRS, inner root sheath; ORS, outer root sheath; PTMA, prothymosin alpha; TB4, thymosin β4; TP, thymic peptide; TYL, thymulin

Treatment of Breast Cancer Lytic Skeletal Metastasis Using a Model in Nude Rats

Cancer is a life-threatening disease, not as a result of the primary tumor that can be removed surgically in the vast majority of cases but from its metastatic spread to distant parts of the body. These metastases are often seen as a hopeless end-stage of the cancer disease and at this time only palliative treatments are applied. Some of the most prevalent solid tumors, such as breast-, lungand prostate cancers, metastasize into the skeleton and cause either osteolytic (destructive) or osteoblastic lesions. Both types are often accompanied by bone pain and increased bone fragility and thus are reason for extended suffering. In breast cancer, bone is the site of first distant relapse and the clinical course of these women is relatively long, with a median survival of 2-3 years (1, 2). Lytic skeletal metastases are present in over 90% of patients who die from breast cancer (3). Many factors are involved in the pathogenesis of lytic skeletal lesions among which the proteins osteopontin (OPN) and bone sialoprotein II (BSPII) are considered to play an important role. In patients with primary breast cancer, elevated serum BSPII was recognized as prognostic marker of subsequent bone metastasis and was associated with poor survival (4-8). BSPII is a noncollagenous protein of the extracellular bone matrix and a member of the SIBLING (Small Integrin-Binding Ligand, N-linked Glycoprotein) family. The SIBLINGs are mainly clustered on human chromosome 4, and include bone sialoprotein II, osteopontin, dentin matrix protein 1 (DMP1), matrix extracellular phosphoglycoprotein (MEPE) and dentin sialophosphoprotein (DSPP) (12). These proteins are normally expressed in mineralizing tissues of bone and teeth but are also found in different cancers (13). In normal bone, BSPII is expressed by osteoblasts, osteoclasts and other skeleton-associated cell types, especially at sites of new mineral formation (12, 14-16). In this case, BSPII is a potential nucleator of hydroxyapatite formation and a specific marker of osteoblast differentiation (14). The sialoprotein is involved in hydroxyapatite and collagen binding, as well as in the attachment of bone cells including fibroblasts, osteoblasts and osteoclasts to solid surfaces,

IDK1 is a rat monoclonal antibody against hypoglycosylated bone sialoprotein with application as biomarker and therapeutic agent in breast cancer skeletal metastasis

Changes in glycosylation are salient features of cancer cells. Here, we report on the diagnostic and therapeutic properties of IDK1, an antibody against tumour associated, hypoglycosylated bone sialoprotein (hypo‐BSP). The affinity of the rat monoclonal antibody IDK1 for hypo‐BSP, as determined by microscale thermophoresis, was three orders of magnitude higher than for mature BSP, whereas the mouse monoclonal antibody used had similar affinity for both BSP forms. IDK1 showed no activity against the proliferation or migration of normal or cancer cells growing in vitro. In vivo, however, IDK1 caused dose‐dependent regression of soft tissue and skeletal lesions in nude rats harbouring human MDA‐MB‐231 cells. At optimal dose, 80% of the treated rats showed complete remission of all tumour lesions. Analysis of BSP expression in vitro by fluorescence‐activated cell sorting (FACS) and immunocytochemistry showed basal levels of this protein, which were visible only in a fraction of these cells. Cells of the metastatic cell lines MDA‐MB‐231 and PC‐3 were more often positive for hypo‐BSP. In addition, there was co‐expression of both forms in some cells, but almost no co‐localization; rather, hypo‐BSP was present in the nucleus, and mature BSP was detected extra‐cellularly. Normal osteoblasts and osteoclasts were negative for hypo‐BSP. Breast cancer tissue, however, showed strong expression of mature BSP, which was present intra‐cellularly as well as in vesicles outside cells. Hypo‐BSP was present mainly in lesions from skeletal sites, thus explaining the antineoplastic activity of IDK1, which was high in lesions growing in the vicinity of the skeleton but low in lesions growing subcutaneously. Finally, hypo‐BSP was detected in specimens from breast cancer patients, with a significantly greater intensity in skeletal metastases as compared to the respective primary cancers. In conclusion, IDK‐1 is an antibody with diagnostic and therapeutic applications in skeletal metastases of breast cancer.