PUTRESCINE ACCUMULATION IN HUMAN PULMONARY TUMORS

Type II pneumocytes and Clara cells, both epithelial cells that posses s an active uptake system for polyamines, have been identified as poss ible precursor cells of at least some types of lung rumours. In this s tudy we have investigated whether human pulmonary tumours exhibit putr escine uptake. Lung slices From both tumoral tissue and non-tumoral ti ssue, obtained from patients undergoing surgery for lung cancer, were incubated with radiolabelled putrescine at both 37 degrees C and 4 deg rees C. The accumulation of putrescine was evaluated by its apparent k inetic parameters, in the presence or absence of cystamine, and by aut oradiography. The investigated tumoral tissue (six squamous carcinomas and five adenocarcinomas) did not show accumulation of putrescine abo ve that attributable to simple diffusion, except for one adenocarcinom a. In this specimen autoradiography showed that the accumulation was n ot specifically associated with any particular cell type, hut that pra ctically every cell accumulated putrescine, We conclude that human pul monary rumours do not accumulate polyamines in a manner similar to nor mal pulmonary epithelial cells.