Table 4.

TDO2 and IDO1 expression in human tumor cell lines

 Tumor type TDO2 only IDO1 only TDO2 and IDO1 Total Colorectal carcinoma 5/11 1/11 0/11 6/11 Glioblastoma 1/8 3/8 1/8 5/8 Leukemia 1/4 0/4 0/4 1/4 Lymphoma 0/4 0/4 0/4 0/4 Melanoma 0/12 2/12 0/12 2/12 Mesothelioma 1/7 2/7 3/7 6/7 Myeloma 1/3 0/3 0/3 1/3 Head and neck carcinoma 1/11 2/11 5/11 8/11 Ovarian carcinoma 0/1 1/1 0/1 1/1 Pancreatic adenocarcinoma 0/5 3/5 1/5 4/5 NSCLC 5/7 0/7 1/7 6/7 SCLC 0/6 0/6 0/6 0/6 Sarcoma 0/6 0/6 2/6 2/6 Breast carcinoma 1/4 1/4 0/4 2/4 Bladder carcinoma 0/3 1/3 2/3 3/3 Hepatocarcinoma 0/2 0/2 0/2 0/2 Gall-bladder carcinoma 0/1 0/1 1/1 1/1 Renal cell carcinoma 4/9 1/9 0/9 5/9 Total 20/104 17/104 16/104 53/104
• Expression of TDO2 an IDO1 was evaluated by RT-PCR on RNA isolated from human tumor cell lines. NSCLC: non small cell lung carcinoma, SCLC: small cell lung carcinoma. In some tumor types, such as melanoma, the proportion of TDO2-expressing tumor lines is lower than the proportion of TDO2-expressing tumor samples (see Table 1). Two factors may explain this difference: (i) during establishment of the cell lines, TDO-expressing tumor cells may have been counterselected because of their tryptophan-depleting effect, as in most cases the cell lines were established in the absence of TDO inhibitor, and (ii) TDO might also be expressed by some stromal cells, such as activated macrophages, which are present in tumor samples and absent in tumor cell lines.