Expression levels of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and focal adhesion kinase in patients with multiple myeloma and their relationship to clinical stage and extramedullary infiltration

We explored the expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and focal adhesion kinase (FAK) mRNA and protein, and analyzed the relationship between expression levels and clinical staging and extramedullary infiltration in patients with multiple myeloma (MM). The expression levels of mRNA and protein were measured by fluorescence quantitative polymerase chain reaction (FQ-PCR) and Western blotting. Expressions of PTEN and FAK mRNA were significantly different between patients with MM and controls. Spearman bivariate correlation analysis showed that PTEN mRNA was significantly negatively correlated with FAK mRNA. PTEN and FAK mRNA expressions were significantly different between patients with stage I+II MM and stage III MM. No difference was found in PTEN mRNA expression, whereas FAK mRNA expression was significantly different between patients with MM with and without extramedullary infiltration. PTEN protein was higher and total FAK (T-FAK) protein was significantly lower in six controls than in 12 patients with stage III MM. Phosphorylated FAK (p-FAK) protein was measured as 0.082 +/- 0.040 in 11 patients with MM, but not detected in six controls. No significant difference of PTEN and T-FAK protein was found, while p-FAK protein was significantly different between patients with MM with and without extramedullary infiltration. These results indicate that abnormal expression of PTEN and FAK in patients with MM may be associated with disease progression and extramedullary infiltration.