Differential Expression of SI9 Ribosomal Protein, Laminin-binding Protein, and Human Lymphocyte Antigen Class I Messenger RNAs Associated with Colon Carcinoma Progression and Differentiation1

Three complementary DNA encoding S19 ribosomal protein (S19), laminin-binding protein (LBP), and HLA class I (HLA-I) genes were isolated from a colon tumor-enriched subtraction library. To evaluate this mRNA expression, surgically removed colon tumors as well as matched normal tissue and human colon carcinoma cell lines showing various differentiation states, anchorage dependence, and proliferation states were examined by Northern blot analysis. The mRNA level of S19 mRNA (0.6 kilobase) was higher in primary colon carcinoma tissue than in matched normal colon tissue in 5 of 6 cases. In 2 of 4 cases, the expression of LBP mRNA (1.2 kilobases) was higher in carcinoma than in normal tissue. In 12 human colon cell lines, the level of LBP mRNA was higher in poorly differentiated cells. On the other hand, HLA-I mRNA (1.7 kilobases) was higher in well-differentiated cells. Although the S19 mRNA was expressed in both welland poorly differentiated cells, a concomitant increase with tumor progression was observed in two pairs of cell lines derived from the same patients (SW480 and SW620; COLO201 and COLO205). Anchorage dependence of Inn>rate-treat cd HT29 colon carcinoma cells was correlated with lower levels of S19 and LBP mRN As and higher levels of HLA-I mRNA expression compared with untreated cells. While the expression of S19 and LBP niRNAs was not changed due to cell growth states, HLA-I mRNA levels were found to be low in proliferating HT29 cells but highly induced in contactinhibited cells. In summary, therefore, high expression of S19 and LBP combined with low expression of HLA-I were well correlated with colon carcinoma cells of higher malignant potential.