Array-based comparative genomic hybridization of circulating esophageal tumor cells

Abstract

Esophageal squamous cell carcinoma (ESCC) shows a high frequency of lymphatic and/or systemic metastasis, even when the tumor invades only the submucosa. To investigate the genetic alterations in circulating esophageal tumor cells, we performed array-based comparative genomic hybridization (CGH) analysis of 8 DNA samples of xenografts, which were previously established from the thoracic duct lymph of 13 ESCC patients. A total of 5 loci (or genes), 10q21.3 (EGR2), 11q13.3 (CCND1/CyclinD1, FGF4, and EMS1), 11q14 (PAK1), and 22qtel (ARSA) were found to be candidate amplified loci in the xenograft. In contrast, a total of 24 loci including 9p21 (p16 and MTAP) were found to be homozygously deleted candidates in the xenograft. Both p16 homozygous deletion and CCND1 amplification were detected in 6 (75%) and 5 (62.5%) of the 8 xenografts. Furthermore, by quantitative Southern blot analysis, we found p16 homozygous deletion in 30.8% (8/26) of the primary tumors and in 50% (4/8) of the metastasized lymph nodes. The frequency of CCND1 amplification and p16 homozygous deletion is suggested to be associated with ESCC progression. Matrigel invasion assays of p16-deleted ESCC cells showed that restoring wild-type p16 activity into the cells significantly inhibits tumor-cell invasion, suggesting that p16 inactivation could be involved in ESCC invasion. This is the first report showing the genetic alteration of concealed tumor cells in the thoracic duct lymph. The present gene list should be helpful for identifying new amplified and deleted genes in primary ESCCs as well as in metastasized lymph nodes.

Tracing PAKs from GI inflammation to cancer

“…In order to identify genetic changes within oesophageal tumour cells, one study used an ESCC xenograft model 15 146. Lymph fluid collected from patients with ESCC was injected into nude mice, and analysed via array based comparative genomic hybridisation.…”

“…Overall, PAK1 and PAK4 are the most investigated of all PAKs, and have been brought into focus due to their association with various malignancies 1. PAK overexpression contributes to tumour invasiveness in uveal melanoma,7 8 neurofibromatosis,9 breast,10 11 cervical,12 colon,13 14 oesophageal,15 gastric,16 17 hepatic,18 lung,19 ovarian,20 prostate21 22 and thyroid cancer 23. PAKs were also correlated to inflammatory diseases such as rheumatoid arthritis24 and asthma 25.…”

Chromosomal and Genomic Variations in Esophageal Squamous Cell Carcinoma: A Review of Technologies, Applications, and Prospections

“…Southern blot, as a conventional method to detect specific DNA sequence, has its limitations such as the harmful radiation generated from radioisotopes, which is needed for detection of DNA sequence. Nowadays, this method used as a validation tool to demonstrate the accuracy of other methods, such as quantitative polymerase chain reaction (qPCR) 19 and array-based comparative genomic hybridization (CGH ) 20 , 21 .…”

Fluctuation of Rac1 activity is associated with the phenotypic and transcriptional heterogeneity of glioma cells

“…By contrast, knockdown of the four membrane-related invasion-associated genes or Elmo1 increased the expression of Egr2, which suggests that there are negative-feedback loops between the invasive phenotype and Egr2 expression. Microarray analyses have revealed upregulation of Egr2 in metastatic squamous cell carcinomas (Kim et al, 2006;Liu et al, 2008). Furthermore, in fibroblasts infected with Kaposi sarcoma-associated herpesvirus, Egr2 induces MMPs and extracellular matrix metalloproteinase inducer (Emmprin) (Dai et al, 2012).…”