Correlation of sorcin overexpression to multidrug resistance of human gastric cancer cell line SGC7901

Objective: Vincristine (VCR)-resistant gastric cancer cell line SGC7901/VCR is a typical multidrug resistant (MDR) cell line with high expression of P-glycoprotein (P-gp). However, verapamil (VRP), the inhibitor of P-gp, can not totally reverse the drug resistance, indicating that additional mechanisms must contribute to the MDR phenotype. Our previous study showed that sorcin, a calcium-binding protein, is significantly up-regulated in SGC7901/VCR cells. This study was to explore the role of sorcin in the development of MDR in human gastric cancer cell line SGC7901.

Methods: The full length sorcin cDNA was isolated by reverse transcription-polymerase chain reaction (RT-PCR). The FLAG-sorsin-pcDNA3.1 plasmid was constructed and transfected into SGC7901 cells. The mRNA and protein levels of sorcin in stable clones were detected by RT-PCR and Western blot. The sensitivity of SGC7901 cells to chemotherapeutic drugs was detected using MTT assay. Then sorcin-transfected SGC7901 cells (SGC-F-Sor) were transfected with sorcin antisense oligonucleotides (ASO). The VCR-sensitivity of SGC7901 cells was determined by MTT assay.

Results: The full-length sorcin cDNA (616 bp) was amplified by RT-PCR. The FLAG-sorsin-pcDNA3.1 plasmid was constructed successfully. The mRNA and protein levels of sorcin were up-regulated in SGC-F-Sor cells. Overexpression of sorcin produced 8.87 folds of VCR-resistance, 6.13 folds of adriamycin (ADM)-resistance, 6.67 folds of taxol-resistance, and 2.80 folds of 5-fluorouracil (5-FU)-resistance. However, when SGC-F-Sor cells were transfected with sorcin ASO, down-regulation of sorcin expression and increased sensitivity to VCR were observed.

Conclusions: Overexpression of sorcin could induce low level of MDR in SGC7901 cells, indicating that sorcin is associated with MDR of SGC7901 cells. Sorcin maybe be a target of MDR reversal in gastric cancer cells.