BIPOLAR (NEURAL AND MYOBLASTIC) PHENOTYPE IN CELL-LINES DERIVED FROM HUMAN GERM-CELL TUMORS OF TESTIS

Non-seminomatous germ cell tumours of the testis (NSGCT) form a hetero geneous group of neoplasms. Cell lines derived from NSGCT may provide useful data concerning the biology of neoplasic precursor germ cells, differentiation of tumour stem cells and the relationship between vari ous tissue components of these rumours. Four NSGCT were studied, two m ixed rumours composed of teratocarcinoma, yolk sac and trophoblastic e lements, and two malignant teratomas with a massive neuroectodermal co mponent, equivalent to primary neuroectodermal tumours (PNET) of the t estis. The explanted rumours gave rise to various cell populations. in cluding epitheloid cells, flattened large cells, spindle cells and tea r drop cells of neuroblastic type. Ultrastructurally, cultured cells e xpressed various degrees of neural and muscular differentiation: neuro secretory granules, intermediate filaments of glial nature, and filame nts resembling Z-bands. Cultured cells showed the expression of severa l neural and muscular markers, including neurofilaments, cytokeratin, actin, desmin, neuron-specific enolase, glial fibrillary acidic protei n and HNK-1. In addition, three cases expressed HBA-71 antigen and two expressed MyoD1 protein. All cases were aneuploid, and an isochromoso me 12p, i(12p), was detected in three cases. Myoblastic and neural cel ls are the predominant tumour cells that grow in vitro, independent of the nature and composition of the primary germ cell tumour. A histoge netic relationship between germ cell tumours and small round cell rumo urs of childhood is suggested.