Phenotype of bone metastases of non-small cell lung cancer: epidermal growth factor receptor expression and K-RAS mutational status.

Bone metastasis is a frequent complication of lung cancer progression, however, studies on bone metastatic tissues are scanty. Here we have collected a small cohort of 11 non-small cell lung cancer cases where primary tumors and corresponding bone metastases were available for pathological analysis. We have tested two molecular markers: EGFR protein expression and K-RAS mutation at codon 12 using immunohistochemistry and RFLPPCR, respectively. We have shown that using improved protocols, EGFR protein (both the extracellular as well as the cytoplasmic domain) is readily detectable in decalcified bone tissue. We found that the EGFR expression status is highly similar in bone metastases compared to the primary tumors, although the expression levels may change. Individual comparison of corresponding primary and metastatic NSCLC tissues indicated that downregulation of EGFR was a rare event (2/11) compared to upregulation (4/11) in bone metastases. On the other hand, our data indicate that the K-RAS mutational status of the primary tumor does not predict the status of the bone metastatic tissue of NSCLC, since we have observed both emergence of mutant clones in metastases from wild-type (wt) primary tumors and loss of mutant clones in metastases from mutant primaries in addition to the maintained mutant status. Our data support that at least two progression models occur in NSCLC, the samegene as well as the clonal selection one. It is noteworthy that in NSCLC cases with wt- or mutant KRAS, downregulation of EGFR expression was a rare event although upregulation in bone metastases was observed more frequently in wt K-RAS cases.

EGFR and VEGFR2 protein expressions in bone metastases of clear cell renal cancer.

BACKGROUND: EGFR and VEGFR2 protein expressions are hallmarks of clear cell renal cancer (RCC) with questionable prognostic impact. The skeletal system is one of the most common metastatic sites of RCC. Unfortunately, there are no data for EGFR and VEGFR2 protein expression in such lesions. MATERIALS AND METHODS: Twenty cases of bone metastatic clear cell RCC were analyzed. EGFR and VEGFR2 proteins were detected by immunohistochemistry and analyzed by morphometry scoring both % positivity and the intensity. RESULTS: EGFR protein scores were significantly reduced in bone metastases of RCC due to the reduction of EGFR protein expression in about one third of the cases (7/20). The VEGFR2 protein-positive phenotype of clear cell RCC was relatively frequent (7/20, 35%), but was lost in bone metastases (2/20, 10%). CONCLUSION: These data suggest a phenotypic/genotypic change of clear cell RCC during the progression to bones and warrant further investigation.

Protocol modifications influence the result of EGF receptor immunodetection by EGFR pharmDx in paraffin-embedded cancer tissues.

EGF receptor (EGFR) became a useful target for several recently introduced therapies of various cancer types including colorectal, lung, head and neck cancers and glioblastoma. The successful clinical application of these novel molecularly targeted therapies requires the expression of their target, EGFR, determined by nucleic acid based or immunohistochemical techniques. However, until now, immunohistochemistry has not become a reliable diagnostic approach for this purpose. The golden standard for the determination of EGFR protein expression in paraffin-embedded cancer tissues is the EGFR pharmDxTM kit. Here we show that the recommended protocol may not be optimal for EGFR immunodetection. Microwave antigen retrieval and extended primary antibody incubation time converted four out of eight EGFR-negative tumors into EGFR-positive in a study of 50 lung adenocarcinoma cases. Accordingly, we recommend retesting cases negative for EGFR with EGFR pharmDxTM using protocol modifications optimizing antigen retrieval and the incubation periods.