Analyzing expression and phosphorylation of the EGF receptor in HNSCC.

Overexpression of the epidermal growth factor receptor (EGFR) in head and neck squamous cell carcinomas (HNSCC) is considered to cause increased EGFR activity, which adds to tumorigenicity and therapy resistance. Since it is still unclear, whether EGFR expression is indeed associated with increased activity in HNSCC, we analyzed the relationship between EGFR expression and auto-phosphorylation as a surrogate marker for activity. We used a tissue micro array, fresh frozen HNSCC tumor and corresponding normal tissue samples and a large panel of HNSCC cell lines. While we observed substantial overexpression only in approximately 20% of HNSCC, we also observed strong discrepancies between EGFR protein expression and auto-phosphorylation in HNSCC cell lines as well as in tumor specimens using Western blot and SH2-profiling; for the majority of HNSCC EGFR expression therefore seems not to be correlated with EGFR auto-phosphorylation. Blocking of EGFR activity by cetuximab and erlotinib points to increased EGFR activity in samples with increased basal auto-phosphorylation. However, we could also identify cells with low basal phosphorylation but relevant EGFR activity. In summary, our data demonstrate that EGFR expression and activity are not well correlated. Therefore EGFR positivity is no reliable surrogate marker for EGFR activity, arguing the need for alternative biomarkers or functional predictive tests.

Circulating serum miRNA (miR-367-3p, miR-371a-3p, miR-372-3p and miR-373-3p) as biomarkers in patients with testicular germ cell cancer.

PURPOSE: Classic serum tumor markers (human chorionic gonadotropin, α1-fetoprotein and lactate dehydrogenase) have an important role in managing testicular germ cell tumor. Since only 60% of all patients with testicular germ cell tumor have elevations of these markers, there is a need for new biomarkers with greater sensitivity/specificity. miRNAs are deregulated in cancer and could serve as noninvasive serum biomarkers. We explored the role of serum miRNAs as a novel biomarker in patients with testicular germ cell tumor. MATERIALS AND METHODS: Total RNA was isolated from serum. miRNA levels were quantified by quantitative real-time polymerase chain reaction. We assessed the miRNAs miR-302a-3p, 302b-3p, 302c-3p, 367-3p, 371a-3p, 372-3p and 373-3p in a subcohort of 30 patients with testicular germ cell tumor and 18 healthy subjects. Validation was performed in 76 patients treated with inguinal exploration due to suspicion of testicular germ cell tumor, of whom 59 had cancer and 17 had benign disease, and in 84 healthy male subjects. RESULTS: Serum miR-367-3p, 371a-3p, 372-3p and 373-3p levels were significantly increased in patients with testicular germ cell tumor compared to healthy individuals and patients with nonmalignant testicular disease. In particular miR-371a-3p allowed for sensitive (84.7%) and specific (99%) identification of patients with testicular germ cell tumor, thus, outperforming human chorionic gonadotropin or α1-fetoprotein testing. Furthermore, miR-367-3p was increased in nonseminoma compared to seminoma cases. Serum miRNA levels were increased in patients with advanced local stage and metastasis. In 9 patients with localized (clinical stage 1A) testicular germ cell tumor serum miR-371a-3p levels decreased postoperatively, indicating tumor specific release. CONCLUSIONS: miR-371a-3p allows for better identification of testicular germ cell tumor than α1-fetoprotein and human chorionic gonadotropin. It could be helpful for clinically managing testicular germ cell tumor, especially for monitoring surveillance therapy and residual disease after chemotherapy.