Young Kyung Bae

A neural survival factor is a candidate oncogene in breast cancer

Using serial analysis of gene expression (SAGE), we identified a SAGE tag that was present only in invasive breast carcinomas and their lymph node metastases. The transcript corresponding to this SAGE tag, dermcidin (DCD), encodes a secreted protein normally expressed only in the pons of the brain and sweat glands. Array comparative genomic hybridization, fluorescence in situ hybridization, and immunohistochemical analyses determined that DCD is overexpressed in ≈10% of invasive breast carcinomas; in some cases its overexpression is coupled with a focal copy number gain of its locus at 12q13.1, and its expression is associated with advanced clinical stage and poor prognosis. Expression of DCD in breast cancer cells promotes cell growth and survival and reduces serum dependency. Putative high- and low-affinity receptors for DCD are present on the cell surface of breast carcinomas and neurons of the brain. Based on these data we hypothesize that DCD may play a role in tumorigenesis by means of enhancing cell growth and survival in a subset of breast carcinomas.

Gene Promoter Hypermethylation in Tumors and Plasma of Breast Cancer Patients

PURPOSE To measure the hypermethylation of four genes in primary tumors and paired plasma samples to determine the feasibility of gene promoter hypermethylation markers for detecting breast cancer in the plasma. MATERIALS AND METHODS DNA was extracted from the tumor tissues and peripheral blood plasma of 34 patients with invasive breast cancer, and the samples examined for aberrant hypermethylation in cyclin D2, retinoic acid receptor beta (RARbeta), twist and high in normal-1 (HIN-1) genes using methylation-specific PCR (MSP), and the results correlated with the clinicopathological parameters. RESULTS Promoter hypermethylation was detected at high frequency in the primary tumors for cyclin D2 (53%), RARbeta (56%), twist (41%) and HIN-1 (77%). Thirty-three of the 34 (97%) primary tumors displayed promoter hypermethylation in at least one of the genes examined. The corresponding plasma samples showed hypermethylation of the same genes, although at lower frequencies (6% for cyclin D2, 16% for RARbeta, 36% for twist, and 54% for HIN-1). Overall, 22 of the 33 (67%) primary tumors with hypermethylation of at least one of the four genes also had abnormally hypermethylated DNA in their matched plasma samples. No significant relationship was recognized between any of the clinical or pathological parameters (tumor size, axillary lymph node metastasis, stage, or Ki-67 labeling index) with the frequency of hypermethylated DNA in the primary tumor or plasma. CONCLUSION The detection of aberrant promoter hypermethylation of cancer-related genes in the plasma may be a useful tool for the detection of breast cancer.