Early differential expression of two glutaminase mRNAs in mouse spleen after tumor implantation

The influence of progressive tumor growth on phosphate-activated glutaminas e (PAG) expression in splenocytes from mice bearing Ehrlich ascites carcino ma cells was investigated. Implantation of Ehrlich ascites tumor cells in t he peritoneal cavity of mice led to a 2.3-fold stimulation of spleen FAG ac tivity 48 h later. Four days after tumor implantation the glutaminase activ ity had returned to nearly basal value and remained at this level throughou t the tumor development. Northern blot analysis indicated that two species of glutaminase mRNA were expressed in the spleen, which showed a differenti al expression pattern during the first 2 days after tumor implantation. The abundance of the transcript of higher electrophoretic mobility (similar to 3 kb) constantly increased over the first 2 days of tumor growth. The mRNA of lower electrophoretic mobility (similar to 6 kb) peaked at 12 h after t umor implantation and returned to control values at 48 h. These results dem onstrate that tumor has the capability of altering glutaminase expression i n the host spleen. (C) 1998 Elsevier Science Ireland Ltd. All rights reserv ed.