Growth and metastatic behavior of molecularly well-characterized human breast cancer cell lines in mice.

Breast cancer (BC) is a disease with intra- and inter-tumor heterogeneity, and models representing the complete variety of clinical BC phenotypes are not available. We explored the tumor growth potential and metastatic behavior of human BC cell lines and determined whether these cell lines can recapitulate subtype-related biological characteristics of tumors. Eighteen human BC cell lines were implanted under the mammary fat pad of nude mice.

Characterization of BCAR4, a novel oncogene causing endocrine resistance in human breast cancer cells.

Resistance to the antiestrogen tamoxifen remains a major problem in the management of estrogen receptor-positive breast cancer. Knowledge on the resistance mechanisms is needed to develop more effective therapies. Breast cancer antiestrogen resistance 4 (BCAR4) was identified in a functional screen for genes involved in tamoxifen resistance.

Inhibition of multiple vascular endothelial growth factor receptors (VEGFR) blocks lymph node metastases but inhibition of VEGFR-2 is sufficient to sensitize tumor cells to platinum-based chemotherapeutics.

Vascular endothelial growth factor receptors (VEGFR) have important roles in cancer, affecting blood and lymphatic vessel functionality as well as tumor cells themselves. We compared the efficacy of a VEGFR tyrosine kinase inhibitor, PTK787/ZK222584 (PTK/ZK), which targets the three VEGFRs, with blocking antibodies directed against VEGFR-2 (DC101) or VEGF-A (Pab85618) in a metastatic melanoma model. Although all inhibitors exerted comparable effects on primary tumor growth, only PTK/ZK significantly reduced lymph node metastasis formation.

Small, potent, and selective diaryl phosphonate inhibitors for urokinase-type plasminogen activator with in vivo antimetastatic properties.

A set of small nonpeptidic diaryl phosphonate inhibitors was prepared. Some of these inhibitors show potent and highly selective irreversible uPA inhibition. The biochemical and modeling data prove that the combination of a benzylguanidine moiety with a diaryl phosphonate ester results in optimized molecules for derivatizing the serine alcohol in the uPA active site.

Suppression of rat breast cancer metastasis and reduction of primary tumour growth by the small synthetic urokinase inhibitor WX-UK1.

The serine protease uPA (urokinase-type plasminogen activator) and its receptor uPAR (CD87) are often elevated in malignant tumours, hence, inhibition of this tumour-associated plasminogen activation system provides an attractive target for therapeutic strategies. WX-UK1, a derivative of 3-aminophenylalanine in the L-conformation with inhibitory antiproteolytic properties, was tested for its specificity spectrum using specific chromogenic paranitroanilide peptide substrates. The corresponding D-enantiomer of WX-UK1 was used as a control.

Progesterone antagonists and progesterone receptor modulators in the treatment of breast cancer.

Progesterone antagonists (PAs) (antiprogestins) or progesterone receptor modulators (PRMs) form an interesting category of new hormonal agents in the treatment of breast cancer. In vitro, antiproliferative effects of different PAs are mainly observed in estrogen-stimulated growth of PR-positive tumor cell lines. Both progestin agonist/antagonist actions on mammary tumor cells are dependent on the type of cell line, culture medium and concentrations of the PAs used, and type of biologic response measured.

Urokinase-type-plasminogen-activator (uPA) production by human breast (myo) fibroblasts in vitro: influence of transforming growth factor-beta(1) (TGF beta(1)) compared with factor(s) released by human epithelial-carcinoma cells.

The urokinase-type plasminogen activator (uPA) may be considered as a key enzyme in the processes of cancer cell invasion and metastasis. Evidence has been presented that, in breast stroma, uPA is expressed predominantly by myofibroblasts located at the invasive areas of the tumor. To examine whether transforming growth factor type-1 (TGF beta(1)) produced by breast-carcinoma cells is a candidate responsible for the induction of uPA-producing myofibroblasts, we studied in vitro the capacity of normal and tumor-derived human breast fibroblasts to express uPA and the myofibroblast marker alpha-smooth-muscle actin in response to TGF beta(1).

Novel endocrine therapies in breast cancer.

Endocrine therapy of breast cancer consists of a variety of both medical and surgical ablative treatment modalities, but ablative therapy is increasingly replaced by medical treatment. Most endocrine therapies have more than one endocrine effect, frequently together with direct growth inhibitory actions via receptors. Endocrine therapy can be effective in all phases of the disease, but curative only in early disease while in advanced cancer it can only prolong survival.

In vitro and in vivo studies of substance P receptor expression in rats with the new analog [indium-111-DTPA-Arg1]substance P.

Unlabelled: We evaluated the potential usefulness of a new radiolabeled substance P (SP) analog, [111In-DTPA-Arg1]SP, as a radiopharmaceutical for the in vivo detection of SP receptor-positive (SPR+) immunologic disorders (i.e., inflammatory bowel disease and arthritis) and tumors (i.

Evaluation in vitro and in rats of 161Tb-DTPA-octreotide, a somatostatin analogue with potential for intraoperative scanning and radiotherapy.

The characteristics of terbium-161 diethylene triamine penta-acetic acid (DTPA) labelled octreotide with respect to specific binding to somatostatin (octreotide) receptors on rat brain cortex membranes, biological activity, uptake and excretion by isolated perfused rat livers and metabolism in vivo in normal and tumour-bearing rats were determined and compared to those of indium-111 DTPA-octreotide. The results of the binding studies demonstrate that 161Tb-DTPA-octreotide is a high-affinity radioligand for somatostatin receptors, with an affinity comparable to that of 111In-DTPA-octreotide. Rat growth hormone secretion inhibition experiments showed that 161Tb-DTPA-octreotide has a similar potency to 111In-DTPA-octreotide.

Pre-clinical and clinical treatment of breast cancer with antiprogestins.

Antiprogestins form a new potential treatment modality for breast cancer and their mode of action has been assessed in vitro on several breast cancer cell lines, in vivo in rats with dimethylbenzanthracene (DMBA)-induced mammary tumours and in vivo in patients with metastatic breast cancer. In vitro in serum-free medium, the progestin Org 2058 and antiprogestins RU486 and Org 31710 caused a dose-dependently stimulated MCF7 cell growth. Both antiprogestins dose-dependently inhibited the oestrogen-stimulated proliferation of progesterone receptor (PgR)-rich T-47D cells in DCC medium.

A new radiolabelled somatostatin analogue [111In-DTPA-D-Phe1]RC-160: preparation, biological activity, receptor scintigraphy in rats and comparison with [111In-DTPA-D-Phe1]octreotide.

We have evaluated the potential usefulness of indium-111 labelled [DTPA-D-Phe1]RC-160, derived from the octapeptide somatostatin analogue RC-160, as a radiopharmaceutical for the in vivo detection of somatostatin receptor-positive tumours. For this purpose 111In-and 115In-labelled [DTPA-D-Phe1]RC-160 was tested for its biological activity, and applied for somatostatin receptor scintigraphy in vivo to rats bearing the transplantable rat pancreatic tumour CA20948, which expresses somatostatin receptors. We previously described the development of the 111In-labelled somatostatin analogue [DTPA-D-Phe1]octreotide and its use in the in vivo visualization of somatostatin receptor-positive tumours in rats and in humans.

Radioiodinated somatostatin analogue RC-160: preparation, biological activity, in vivo application in rats and comparison with [123I-Tyr3]octreotide.

We have evaluated the potential usefulness of the radioiodinated octapeptide RC-160, a somatostatin analogue, which might serve as a radiopharmaceutical for the in vivo detection of somatostatin receptor-positive tumours. For this purpose, iodine-123 and iodine-125 labelled RC-160 was tested for biological activity and applied in vivo in rats bearing the transplantable rat pancreatic tumour CA20948, which expresses somatostatin receptors. Our group has recently described the in vivo visualization of such tumours in rats and in humans with the radioiodinated somatostatin analogue [Tyr3]octreotide.

In vivo application of [111In-DTPA-D-Phe1]-octreotide for detection of somatostatin receptor-positive tumors in rats.

Radioiodinated somatostatin analogues are useful ligands for the in vitro and in vivo detection of somatostatin receptors. [111In-DTPA-D-Phe1]-octreotide, a somatostatin analogue labeled with a different radionuclide, also binds specifically to somatostatin receptors in vitro. In this study we investigated its in vivo application in the visualization of somatostatin receptor-positive tumors in rats.

Treatment of breast cancer with different antiprogestins: preclinical and clinical studies.

Unlabelled: Treatment with antiprogestins is a new treatment modality for breast cancer. Previously, in rats with DMBA-induced mammary tumors we observed significant growth inhibitory effects of chronic treatment with the antiprogestin mifepristone (RU486). In addition, in 11 postmenopausal breast cancer patients, we observed one objective response, six instances of short-term stable disease, and four instances of progressive disease.

Growth factor-receptor pathway interfering treatment by somatostatin analogs and suramin: preclinical and clinical studies.

Unlabelled: Interference in growth factor mediated pathways is a new strategy in the treatment of cancer. Somatostatin analogs can inhibit hormone and growth factor secretion, while suramin can block the binding of several growth factors to their receptors. In addition, somatostatin analogs can cause direct growth inhibitory effects after binding to tumoral somatostatin receptors.

The somatostatin analog Sandostatin (SMS201-995) in treatment of DMBA-induced rat mammary tumors.

The effects of treatment with a somatostatin analog (Sandostatin, SMS201-995) were investigated in female rats with dimethylbenzanthracene (DMBA)-induced rat mammary tumors. A 3-week treatment was performed using sandostatin, the LHRH-agonist buserelin alone, or buserelin in combination with sandostatin. Twice daily sandostatin treatment was performed with dosages of 0.

Endocrine and antitumor effects of combined treatment with an antiprogestin and antiestrogen or luteinizing hormone-releasing hormone agonist in female rats bearing mammary tumors.

Rats bearing mammary tumors induced with dimethylbenzanthracene were treated with the antiprogestin mifepristone (RU486; 10 mg/kg.day, sc), the antiestrogen tamoxifen (400 micrograms/kg.day, sc), LHRH agonists administered by either sc injections (buserelin; 40 micrograms/kg.

Comparison of the actions of the antiprogestin mifepristone (RU486), the progestin megestrol acetate, the LHRH analog buserelin, and ovariectomy in treatment of rat mammary tumors.

The effects of the synthetic antiprogestin mifepristone (RU486) on growth of dimethylbenzanthracene (DMBA)-induced mammary tumors in female rats were investigated. Prophylactic treatment with mifepristone (10 mg/kg/day) for 3 weeks starting from the day of first DMBA injection resulted in a doubling of the average tumor latency period (81 +/- 16 days, n = 17 treated, versus 39 +/- 5 days, n = 75 controls; P less than 0.005) and was accompanied by a significant growth retardation as shown by lower body weight increments.

Direct inhibitory effects of somatostatin (analogues) on the growth of human breast cancer cells.

Various hormones and growth factors are involved in the growth regulation of breast (tumor) cells. In this report we show for the first time that an analogue of the neuropeptide somatostatin (Sandostatin) can also influence the proliferation of human breast cancer cells (MCF-7), namely, in an inhibitory fashion. With respect to dose-response relationship a bell-shaped curve was observed with the maximal inhibition of tumor cell growth at a sharply defined amount of Sandostatin (10 nM).