Recurrent malignant Triton tumour: first report on a long time survivor.

Malignant Triton tumour represents an extremely rare mesenchymal malignancy exhibiting histopathologic patterns of peripheral nerve sheath tumours and rhabdomyoblastic components, the latter usually determining the mostly fatal outcome. We report on a 26-year old patient diagnosed with malignant Triton tumour who developed multiple recurrences despite repeated aggressive surgery, chemo- and radiotherapy during an 8-year period. After Northern blotting analysis of an excised in-transit metastasis had revealed expression of retinoic receptors alpha and gamma, the patient received experimental treatment with isotretinoin and interferon-alpha for one year and remains without any evidence of disease for more than three years. This is the first report on a long-term survivor of multiple recurrences of malignant Triton tumour.

Heregulin and retinoids synergistically induce branching morphogenesis of breast cancer cells cultivated in 3D collagen gels.

C-erbB and retinoid receptor signaling control mammary epithelial cell proliferation, differentiation, and morphology. Here, we examined the morphogenetic activities of c-erbB specific ligands such as heregulin and of retinoids on non-malignant (primary, MTSV1-7) and malignant (T47D, SKBR-3) human mammary epithelial cells (HMEC) cultivated in 3D collagen type I gels. These cells are positive for both c-erbB and retinoid receptors. Non-malignant primary HMEC spontaneously formed branched structures in collagen, whereas SV40 large T antigen-immortalized non-tumorigenic MTSV1-7 spontaneously formed balls and required heregulin or retinoid X receptor alpha-selective retinoid Ro 25-7386 for branching, which was further stimulated by combination of both types of agents. In malignant cells, heregulin alone induced ball formation and cooperated either with Ro 25-7386 (T47D) or with retinoic acid receptor alpha-selective AM580 (SKBR-3) for branching morphogenesis, which was accompanied by changes in the subcellular distribution of alpha(2)beta(1)-integrin and E-cadherin, and by down-regulation of c-erbB-2, -3, or -4. Heregulin and/or retinoids correspondingly increased the integrin-dependent adhesion of malignant cells to type I collagen. Our data demonstrate cooperative signaling of c-erbB and retinoid receptor pathways at the levels of morphogenesis and immunophenotypic differentiation.