Expression of cell proliferating genes in patients with non-small cell lung cancer by immunohistochemistry and cDNA profiling.

Thymidine kinase 1 (TK1) is a key enzyme involved in the synthesis of DNA precursors and thus, cell proliferation-dependent. Antibodies against TK1 have provided attractive tools for cancer diagnosis. Expression of TK1 in 158 non-small cell lung cancer (NSCLC) patients with 59 adenocarcinoma (AC) and 99 squamous cell carcinoma (SCC) was determined by anti-TK1 monoclonal antibody (mAb) 1E3 (AC, n=50; SCC, n=70). Parallel tumor sections were stained for Ki-67 (MIB-1), and TK1 expression was also investigated with anti-TK1 chicken IgY Ab (AC, n=9; SCC, n=29; normal lung tissues, n=10). In one AC and one SCC patient, gene profiling was done by cDNA array. Using the mAb 1E3, a significantly higher TK1 labeling index (LI) of AC patients was found (68%) compared to the LI of Ki-67 (36%). This difference was due to a significantly higher TK1 LI of tumor stage II and grade 2. Although no difference in the LI of TK1 and Ki-67 of SCC patients was found (54 vs. 53%), significantly higher TK1 LI of SCC patients of tumor grade 1 was found. Using the anti-TK1 IgY Ab, a higher TK1 LI of AC patients (78%) and SCC patients (66%) was found compared to staining with mAb 1E3 (68 vs. 54%), but it was not significantly different. Samples stained only for TK1 represented mostly tumor stages I and II and grades 1 and 2 of both AC and SCC. AC patients whose samples stained only for Ki-67 were found to be in stage I and grade 1. cDNA profiling showed that the expression of BRCA1, cyclin B1 and cdc2p34 was higher in AC compared to SCC, while the expression of IGFBP-3 and EGFR was higher in SCC. TK1 is apparently a more reliable marker in AC patients than Ki-67. However, a combination of the two markers may help identify patients of different stages and grades more efficiently, and cyclin/kinase complexes and growth factors/receptors may be useful markers in distinguishing AC from SCC.

Cytosolic thymidine kinase is a specific histopathologic tumour marker for breast carcinomas.

Thymidine kinase 1 (TK1), an enzyme involved in the synthesis of precursors for DNA, and thus proliferation dependent, has been suggested as a good tumour marker. We have recently developed poly/monoclonal antibodies against TK1, which proved useful for diagnostics in both serum and immunohistochemistry of cancer patients. The anti-TK1 monoclonal antibodies (mAbs) 1D11 and 1E3 were characterized by Western blot, immunoprecipitation and flow cytometry. TK1 mAbs and Ki-67 mAb were then used for immunohistochemistry staining of tumour sections from 54 patients with ductal infiltrated breast carcinoma. Results showed the relative number of patients with positively stained tumours for TK1 (mAb 1D11) and for Ki-67 (mAb MIB-1) were 47 and 41%, respectively, significantly related (p=0.007). Combination of TK1 mAbs 1D11 and 1E3 increased this number to 56%, due to detection of a significantly higher number of patients with grade 2 tumours. Patients with stage II and grade 2 tumours showed significantly higher TK1 staining when compared to stage I and grade 1. Ki-67 staining was significantly higher in stage III and grade 3. The tumours only stained for TK1 represented higher stages and grades, while tumours staining only for Ki-67 were of lower stages and grades. Combining TK1 and Ki-67 increased the number of patients with positively stained tumours to 69%. In conclusion, TK1 is a reliable marker for identification of patients with grade 2 tumours. The highest number of patients with positively stained tumours were obtained when both TK1 and Ki-67 markers were used.