Differential Proteome Analysis of Human Neuroblastoma Xenograft Primary Tumors and Matched Spontaneous Distant Metastases

Metastasis formation is the major cause for cancer-related deaths and the underlying mechanisms
remain poorly understood. In this study we describe spontaneous metastasis xenograft mouse models
of human neuroblastoma used for unbiased identification of metastasis-related proteins by applying an
infrared laser (IR) for sampling primary tumor and metastatic tissues, followed by mass spectrometric
proteome analysis. IR aerosol samples were obtained from ovarian and liver metastases, which were
indicated by bioluminescence imaging (BLI), and matched subcutaneous primary tumors. Corresponding
histology proved the human origin of metastatic lesions. Ovarian metastases were commonly larger
than liver metastases indicating differential outgrowth capacities. Among ~1,900 proteins identified at
each of the three sites, 55 proteins were differentially regulated in ovarian metastases while 312 proteins
were regulated in liver metastases. There was an overlap of 21 and 7 proteins up- and down-regulated at
both metastatic sites, respectively, most of which were so far not related to metastasis such as LYPLA2,
EIF4B, DPY30, LGALS7, PRPH, and NEFM. Moreover, we established in vitro sublines from primary
tumor and metastases and demonstrate differences in cellular protrusions, migratory/invasive potential
and glycosylation. Summarized, this work identified several novel putative drivers of metastasis
formation that are tempting candidates for future functional studies.