Abstract
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Introduction: Recently, the discovery of tumor-related mRNA in the plasma of cancer patients has opened up an exciting era for research in order to pursue the goal of having a simple and cost-effective test for cancer detection and monitoring. However, there are only scanty reports on the effect of centrifugation to collect plasma for mRNA detection. Therefore we designed a study in detecting plasma β-catenin mRNA, a potential marker in colorectal cancer (CRC) detection as we demonstrated previously, with different centrifugation conditions in metastatic CRC patients. In addition, we also explored whether the same batch of plasma samples had carcinoma cells by using a magnetic labeling system for detection. Materials & Methods: We measured the concentration of plasma β-catenin mRNA using quantitative reverse-transcriptase polymerase chain reaction in 30 metastatic CRC patients with different centrifugation conditions which comprised of 400g 8 min, 400g 35 min and 4000g 35 min. Moreover, 2 ml plasma from each of the above centrifugation condition in the same patient cohort was subjected to magnetic sorting using cytokeratin microbeads to detect carcinoma cells. Results: Our results showed that β-catenin mRNA was detected in all plasma samples with 400g 8 min, 400g 35 min but only in 26 plasma samples with 4000g 35 min centrifugation. Besides, the concentration of β-catenin mRNA decreased 2.5 to 12.5 fold when centrifugation condition changed from 400g 8 min to 400g 35 min whereas it decreased 7.5 fold to undetectable level when centrifugation condition further changed from 400g 35 min to 4000g 35 min. Interestingly, carcinoma cells were found in 6 out of 30 plasma samples with 400g 8 min centrifugation whereas it was not detected in samples with other centrifugation conditions. (Figure 1) Conclusions: The sensitivity in plasma β-catenin mRNA detection is inversely correlated to centrifugation force or duration in plasma collection. Besides, higher concentration of plasma β-catenin mRNA was found in samples with 400g 8 min centrifugation and may be associated with the presence of carcinoma cells in the plasma of metastatic CRC patients with the same centrifugation condition. Figure 1 #
[Proc Amer Assoc Cancer Res, Volume 47, 2006]
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