Open AccessFoxp3 overexpression decreases sensitivity to chemotherapy in mouse Lewis lung cancer cells
Author(s) -
Chun Li,
Wei Yang,
Xiaowu Gai,
Yinglin Zhang,
Yang Li,
Haiying Fu
Publication year - 2012
Publication title -
molecular medicine reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.727
H-Index - 56
eISSN - 1791-3004
pISSN - 1791-2997
DOI - 10.3892/mmr.2012.1066
Subject(s) - foxp3 , lung cancer , cancer research , biology , oncogene , cancer , flow cytometry , chemotherapy , mtt assay , cell cycle , immunology , cell growth , immune system , pathology , medicine , genetics
Chemotherapy is the main strategy for the treatment of lung cancer. However,sensitivity to chemotherapy, one of the main factors affecting the survival rateof patients with lung cancer, is extremely poor. Forkhead box P3 (Foxp3) is thekey regulatory gene for the development and function of CD4+CD25+ regulatory Tcells (Tregs). Increased levels of Tregs and Foxp3 expression in the peripheralblood and tumour specimens of cancer patients are associated with tumour progressionand poor prognosis. In addition, certain studies have suggested that Tregs maybe resistant to conventional chemotherapy and thus, enhance tumour immune evasion.Previous studies have demonstrated that Foxp3 is also expressed within tumourcells and that it may mimic the function of Tregs. Currently, the correlationbetween the tumour cell expression of Foxp3 and sensitivity to chemotherapy isunclear. Therefore, it was hypothesised that Foxp3 causes resistance to chemotherapeuticagents in lung cancer cells and that it may consequently promote the progressionof lung cancer. In the current study, the expression of Foxp3 in mouse Lewis lungcancer (LLC) cells was detected using RT-PCR and immunocytochemistry. The overexpressionof Foxp3, which was accomplished by the transient transfection of recombinantpcDNA3.1-Foxp3 or empty plasmids into LLC cells, was confirmed by RT-PCR and westernblot analysis. The inhibition of cell proliferation was measured using MTT assay.The expression of multidrug resistance protein 1 (mdr1) mRNA and its protein product,P-glycoprotein (P-gp), were detected by RT-PCR and flow cytometry, respectively.The results revealed that Foxp3 was expressed by LLC cells. The inhibitory rateof cell proliferation in Foxp3-overexpressing LLC cells compared with those transfectedwith an empty plasmid was significantly decreased following adriamycin (ADM) andmitomycin C (MMC) treatment. The IC50 values of ADM and MMC in Foxp3-overexpressingLLC cells were increased. The expression levels of mdr1 mRNA and P-gp were significantlyupregulated in Foxp3 overexpressing LLC cells. These results suggest that Foxp3reduces the sensitivity of LLC cells to ADM and MMC, thus promoting tumour progression,by upregulating the expression of mdr1 mRNA and P-gp.