Optimal Markers for Real-Time Quantitative Reverse Transcription PCR Detection of Circulating Tumor Cells from Melanoma, Breast, Colon, Esophageal, Head and Neck, and Lung Cancers

Abstract

Background:The detection of circulating tumor cells (CTCs) may prove useful for screening, prognostication, and monitoring of response to therapy. However, given the large background of circulating cells, it is probably necessary to detect 1 cancer cell in >10 6 leukocytes. Although reverse transcription (RT)-PCR is potentially sensitive and specific enough to achieve this goal, success will require the use of appropriate mRNA markers. The goal of this study was to identify optimal marker combinations for detection of CTCs. Methods: An extensive literature and internet database survey was conducted to identify potential markers. We then used real-time quantitative RT-PCR to test for expression of selected potential markers in tissue samples from primary tumors of breast, colon, esophagus, head and neck, lung, and melanoma and normal blood samples. Markers with high expression in tumors and a median 1000-fold lower expression in normal blood were considered potentially useful for CTC detection and were tested further in an expanded sample set. Results: A total of 52 potential markers were screened, and 3-8 potentially useful markers were identified for each tumor type. The mRNAs for all but 2 markers were found in normal blood. Marker combinations were identified for each tumor type that had a minimum

Molecular Markers in Peripheral Blood of Iranian Women with Breast Cancer

“…CK-19 has been successfully used as a marker for detection of certain tumor cells in blood [26]. In addition, it has been studied as potential marker for minimal residual disease in blood [27]. CEA mRNA is another marker which can be detected in almost all epithelial cells including breast cancer [28].…”

Real-time RT-PCR systems for CTC detection from blood samples of breast cancer and gynaecological tumour patients (Review)

“…As cancers often have a great heterogeneity in their gene expression many studies aim to find a suitable set of real-time PCR marker genes for the detection of CTCs. xi et al (149) for example screened a set of 52 potential marker genes to find a set of three to eight marker genes for a number of cancer entities. De Albuquerque et al (140) found a set of marker genes, which could be helpful for the detection of CTCs from blood of metastatic breast cancer patients, Lasa et al (150) described an increase in CTC-detection rate by use of a marker set in comparison to the use of a single gene.…”

Molecular characterization of circulating tumor cells in large quantities of contaminating leukocytes by a multiplex real-time PCR

“…Next, only candidate genes are selected by comparing the corresponding depleted and enriched fractions for minimal expression in the CTCdepleted fraction and significant expression in the CTCenriched fraction [21]. Also less sophisticated methods such as only selecting markers with high expression in tissue samples from primary tumors and a median 1,000-fold lower expression in normal blood [7] have been used. However, our data in Table 3 show that such approaches may not be accurate for EpCAM-enriched samples because the whole blood cell profile prior to CellSearch is not representative for the blood cell profile after CellSearch.…”

“…With the restriction of not using genes more dominantly expressed by CellSearch-enriched leukocytes, any gene set specific for any cancer type can be implemented in the method we described. These genes may represent markers to identify the tissue origin of the CTCs, for example by implementing the markers described by Xi et al [7], as well as more cancer-specific markers such as those useful for drug targeting. The resulting data can be used to further characterize cancer type specific CTCs, thereby potentially improving our insight into biological processes and ultimately patient management.…”

“…Circulating cells with the characteristics of tumor cells of epithelial origin have been demonstrated in blood and bone marrow of prostate, melanoma, colon, esophageal, head and neck, lung and breast cancer patients (reviewed in [1][2][3][4][5][6][7][8][9][10][11]). These cells have not only been shown in patients with metastatic disease, but also in those whose tumors are apparently localized [12,13].…”