Prognostic value and in vitro biological relevance of Neuropilin 1 and Neuropilin 2 in osteosarcoma.

Neoadjuvant chemotherapy in osteosarcoma increased the long-term survival of patients with localized disease considerably but metastasizing osteosarcoma remained largely treatment resistant. Neuropilins, transmembrane glycoproteins, are important receptors for VEGF dependent hyper-vascularization in tumor angiogenesis and their aberrant expression promotes tumorigenesis and metastasis in many solid tumors. Our analysis of Neuropilin-1 (NRP1) and Neuropilin-2 (NRP2) immunostaining in a tissue microarray of 66 osteosarcoma patients identified NRP2 as an indicator of poor overall, metastasis-free and progression free survival while NRP1 had no predictive value. Patients with tumors that expressed NRP2 in the absence of NRP1 had a significantly worse prognosis than NRP1(-)/NRP2(-), NRP1(+) or NRP1(+)/NRP2(+) tumors. Moreover, patients with overt metastases and with NRP2-positive primary tumors had a significantly shorter survival rate than patients with metastases but NRP2-negative tumors. Furthermore, the expression of both NRP1 and NRP2 in osteosarcoma cell lines correlated to a variable degree with the metastatic potential of the respective cell line. To address the functional relevance of Neuropilins for VEGF signaling we used shRNA mediated down-regulation and blocking antibodies of NRP1 and NRP2 in the metastatic 143B and HuO9-M132 cell lines. In 143B cells, VEGFA signaling monitored by AKT phosphorylation was more inhibited by blocking of NRP1, whereas in HuO9-M132 cells NRP2 blocking was more effective indicating that NRP1 and NRP2 can substitute each other in the functional interaction with VEGFR1. Altogether, these data point to NRP2 as a powerful prognostic marker in osteosarcoma and together with NRP1 as a novel target for tumor-suppressive therapy.

Worse prognosis of osteosarcoma patients expressing IGF-1 on a tissue microarray.

BACKGROUND: It is hardly possible to define osteosarcoma (OS) patients at greatest risk for non-response to chemotherapy, metastasis and short survival times. Our goal was the investigation of local expression of insulin-like growth factor (IGF-1) with regard to survival time of OS patients using a tissue microarray (TMA). MATERIALS AND METHODS: Tumor tissue specimens from surgical primary tumor resections were collected from patients with OS. A TMA was composed, sections were stained with rabbit anti-IGF-1 and grading was performed. Statistics involved Kaplan-Meier curves and the log-rank test. RESULTS: We analyzed immunohistochemical expression of local IGF-1 on a TMA based on surgical primary tumor resections of 67 OS patients. The mean clinical follow-up time was 98 months. Twenty-two (33%) OS patients stained negatively and 44 (66%) OS patients stained positively for IGF-1. Significantly shorter survival was detected with expression of IGF-1 (p=0.007). The 5-year survival rate for patients expressing IGF-1 was 63% compared to 92% in patients without expression of IGF-1. Non-responders to chemotherapy and patients with metastasis, who also stained positively for IGF-1 manifested a significantly (p=0.002 and p<0.0001, respectively) shorter survival. CONCLUSION: Expression of local IGF-1 in primary tumor tissue appears to significantly affect the aggressiveness of OS, may predict survival time and, above all, may discriminate patients with non-response to chemotherapy and metastasis. This represents the basis for successful patient selection with regard to the decision process for or against chemotherapy and the choice of the most effective therapeutic drug. It may be a more important marker of tumor progression and indicator of prognosis than serum IGF-1. Novel tumor markers and therapeutic agents targeting the local IGF-1 pathway may increase the likelihood of therapeutic success.

Expression of MSH2 and MSH6 on a tissue microarray in patients with osteosarcoma.

BACKGROUND/AIM: Reliable prognostic factors for the outcome of patients with osteosarcoma (OS) remain elusive. We analyzed the relationship between immunohistochemical expression of deoxyribonucleic acid (DNA) mismatch repair (MMR) proteins, MutS protein homolog 2 (MSH2) and MSH6 using a tissue microarray (TMA) with respect to OS patient demographics and survival time. MATERIALS AND METHODS: We retrieved tumor tissue specimens from bone tissue originating from surgical primary tumor specimens of OS patients to generate a TMA and stained sections with antibodies against MSH2 and MSH6. RESULTS: Tumor resections of 67 patients with a mean follow-up of 98 months were evaluated. MSH2 was expressed in nine (13%), MSH6 in ten (15%) and combined MSH2 and MSH6 (MSH2/6) in six (9%) patients. Significantly shorter survival times were associated with expression of MSH6, MSH2/6, as well as simultaneous non-response to chemotherapy and presence of metastasis. CONCLUSION: The survival time of patients with OS may be predicted by local expression of MSH6 and MSH2/6 in surgical primary tumor resections. This study shows the prognostic value of the local expression of DNA MMR proteins, as markers for poor prognosis of OS patients.