Background: Gastric adenocarsinoma is the first leading fatal malignancy in Iran. Despite advances in novel therapeutics approaches for gastric cancer (GC) patient, tumor dissemination via blood stream to distant organ is still the major cause of death. Therefore, there is urgent need to establish sensitive methods for early detection of disseminated tumor cells in peripheral blood (PB) and bone marrow (BM) specimens of gastric cancer patients.
Methods: In the present study, we use Carcinoma Embryonic Antigen (CEA) as a tumor marker and Glyceraldehyde 3-Phosphate Dehydrogenase (GAPDH) as an internal control to detection and quantification of disseminated tumor cells in PB and BM specimens of affected individuals. Total RNA was extracted from AGS (gastric cancer) cell line and CEA and GAPDH fragments were generated by reverse transcription. The amplified fragments were cloned into pTZ57R/T vector separately. Double cloning of these genes has done into one pTZ57R/T vector. Serial dilution of this recombinant plasmid is used to construct standard curve, each containing a known amount of input copy number. Total RNA was extracted from BP and BM specimens of 35 GC patients. cDNA of the specimens were synthesized by reverse transcription and subjected to Quantitative Real-Time PCR (QRT-PCR).
Results: We developed a highly sensitive and specific quantitative PCR for CEA and GAPDH using Real-Time PCR based on TaqMan technology. CEA mRNA was detected in 23% of PB and 20% of BM specimens. There was no CEA mRNA detecting in control group.
Conclusions: The QRT-PCR for CEA can be a useful technique for detection of micrometastases in the PB and BM specimens of gastric cancer patients.