Abstract 3293: Possible role of SERPINE2 in lymph node metastasis of testicular cancer

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Abstract Objective Testicular germ cell tumors (TGCTs) commonly metastasize to the lymph node or lung. However, it remains unclear which genes are associated with TGCT metastasis. The aim of this study was to identify gene(s) that promote TGCT metastasis. Methods JKT-1 cell-line derived from human testicular seminoma and JKT-HM cell-line, which is the sub-line of JKT-1 with highly metastatic potential, were used. We intraperitoneally administered PBS or conditioned medium (CM) from JKT-1 or JKT-HM into mice with JKT-1 xenografts for 16 days. Metastasis to lymph nodes were examined 5 weeks after JKT-1 inoculation. We performed MTS assay and transwell assay to clarify if CM from JKT-1 and JKT-HM cells promote a proliferation and a migration of JKT-1 in vitro. Then we analyzed RNA expression pattern of JKT-1 and JKT-HM cells using cDNA microarray. The gene of interest was silenced with siRNA or overexpressed using gene transfer technique and confirmed with mouse xenograft model administrated CM itnraperitoneally as we mentioned above. Results In the xenograft model, metastasis of lymph node metastases were identified in 2/5 (40%), 5/9 (56%) and 12/13 (92%) of mice treated with PBS, CM from JKT-1 and CM from JKT-HM, respectively. There was a significant difference in the frequency of lymph node metastasis between mice treated with CM from JKT-1 cells and those treated with CM from JKT-HM cells (p = 0.043). There was no difference in the in vitro proliferation or migration of JKT-1 cells cultured with CM from JKT-HM cells, compared to that with CM from JKT-1. A cDNA microarray analysis showed that JKT-HM cells highly expressed the Serpine peptidase inhibitor, clade E, member 2 (SERPINE2), which encodes a secreted protein. In the xenograft model, lymph nodes metastases were identified in 13/14 (93%), 14/15 (93%), and 8/14 (57%) of mice treated with CM from JKT-HM cells, CM from JKT-HM cells transfected with control siRNA, and CM from SERPINE2-silenced JKT-HM cells, respectively. There was a significant difference in lymph node metastasis between mice treated with CM from JKT-HM cells transfected with control siRNA and those treated with CM from SERPINE2-silenced JKT-HM cells (p = 0.023). Moreover, there was a significant difference in lymph node metastasis between mice treated with CM from JKT-1 cells(3/12, 23%) and those treated with CM from SERPINE2-over-expressing JKT-1 cells (10/12, 83%) (p = 0.0026). Lymph node metastasis occurred more frequently in CM from SERPINE2-over-expressing JKT-1 cells (83%) than in that from JKT-1 cells transfected control vector (8/12, 67%). However, the difference was not statistically significant (p = 0.3458). Conclusion We identified SERPINE2 as a possible promoter of TGCT metastasis. Although further study would be expected, SERPINE2, which is a secreted protein, may be a new target for the therapy against human TGCT. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3293.