Genome-wide copy number analysis of cerebrospinal fluid tumor cells and their corresponding archival primary tumors.

A debilitating complication of breast cancer is the metastatic spread of tumor cells to the leptomeninges or cerebrospinal fluid (CSF). Patients diagnosed with this aggressive clinical syndrome, known as leptomeningeal carcinomatosis, have very poor prognosis. Despite improvements in detecting cerebrospinal fluid tumor cells (CSFTCs), information regarding their molecular biology is extremely limited. In our recent work, we utilized a protocol previously used for circulating tumor cell isolation to purify tumor cells from the CSF. We then performed genomic characterization of CSFTCs as well as archival tumors from the same patient. Here, we describe the microarray data and quality controls associated with our study published in the Cancer Research journal in 2013 [1]. We also provide an R script containing code for quality control of microarray data and assessment of copy number calls. The microarray data has been deposited into Gene Expression Omnibus under accession # GSE46068.

Molecular profiling of tumor cells in cerebrospinal fluid and matched primary tumors from metastatic breast cancer patients with leptomeningeal carcinomatosis.

Although leptomeningeal carcinomatosis is a well-established clinical syndrome, virtually nothing is known about the tumor cells responsible for this particularly aggressive metastatic process. To isolate cerebrospinal fluid-derived tumor cells (CSFTC) from 15 patients with metastatic breast cancer diagnosed with leptomeningeal carcinomatosis, CSF samples were subjected to a two-step method involving immunomagnetic enrichment and fluorescence-activated cell sorting (IE/FACS), a technique previously used for isolating circulating tumor cells (CTC) from blood. CSFTCs were subjected to genome-wide copy number analysis by array comparative genomic hybridization. Genomic profiling was successfully performed for 13 of 15 patients (87%). Copy number analysis in CSFTCs revealed genomic alterations commonly observed in primary breast cancer and CTCs, indicating their malignant origin. Interestingly, 12 (92%) harbored high-level gains on the 8q24 locus, which includes the MYC oncogene. Comparison of CSFTCs against corresponding archival primary tumors in six patients revealed clonal relationships with some divergence. Good concordance among serial samples attested to the reproducibility of the assay. Our approach for isolation and molecular analysis of CSFTCs yielded new insights into the molecular nature of these cells. Further genomic and functional analyses may help elucidate mechanisms by which tumor cells metastasize to the central nervous system.