Identification of side population cells in human lung adenocarcinoma A549 cell line and elucidation of the underlying roles in lung cancer.

The present study aimed to isolate and characterize side population (SP) cells in the human lung cancer A549 cell line, and elucidate the molecular mechanism of SP cells underlying lung cancer. The SP and non-SP (NSP) cells in A549 cells were isolated and their differentiation was analyzed by fluorescence-activated cell sorting. An in vitro plate clone assay, Matrigel® Transwell assay and chemoresistance analysis of the sorted SP and NSP cells were performed. In addition, the sorted SP and NSP cells were injected into BALB/c nude mice to detect their tumorigenic potential in vivo. The expression of ATP-binding cassette sub-family G member 2 (ABCG2) in transplanted tumors was detected by immunohistochemistry. The SP and NSP cells were successfully isolated. The results demonstrated that SP cells accounted for 1.09% of live A549 cells. SP cells produced SP and NSP cells, while NSP cells only produced NSP cells. In addition, SP cells formed more colonies, exhibited improved invasive ability and increased levels of chemoresistance compared with NSP cells in vitro. SP cells demonstrated a higher tumorigenic potential in BALB/c nude mice, and the number of ABCG2-positive cells in the SP xenograft tumors were significantly increased compared with that in the NSP xenograft tumors. The present study indicated that SP cells isolated from the human lung cancer A549 cell line demonstrated increased tumorigenicity, and improved invasive ability and chemoresistance compared with NSP cells. In addition, detection of ABCG2 expression may assist in predicting the chemotherapeutic outcome of patients, and serve as a target for treating lung cancer.

Comparison of postoperative immune function in patients with thoracic esophageal cancer after video-assisted thoracoscopic surgery or conventional open esophagectomy.

AIM: The aim of the study was to compare postoperative immune function in patients with thoracic esophageal cancer (EC) after video-assisted thoracoscopic surgery (VATS) or conventional open esophagectomy. PATIENTS AND METHODS: Medical records were retrospectively analyzed for 228 patients with thoracic EC treated at a single hospital using VATS (n = 52) or conventional open esophagectomy (n = 176). Proportions of CD3(+), CD4(+), CD8(+), and natural kill (NK) cells, as well as the ratio of CD4(+) to CD8(+) cells, were measured in the two groups using flow cytometry on preoperative day (PrD) 1 and postoperative days (PoD) 1 and 7. RESULTS: Proportions of CD3(+), CD4(+), and NK cells as well as the CD4+/CD8+ ratio decreased significantly from PrD1 to PoD1 in both the VATS and open esophagectomy groups. In the VATS group, these parameters had returned to preoperative levels (PrD1) by PoD7. These parameters in open esophagectomy group increased from PoD1 to PoD7 but also lowered significantly to PrD1 by PoD7. The proportion of CD8(+) cells was similar between the two groups at all time points tested. CONCLUSION: Patients may experience less postoperative immune suppression after VATS than after conventional open esophagectomy, and they may recover preoperative immune function more quickly.

[Isolation and identification of side population cells in human lung adenocarcinoma cell line A549].

OBJECTIVE: To isolate and characterize the side population cells (SP cells) in the lung adenocarcinomas cell line A549. METHODS: The protein expression of ABCG2 in human lung adenocarcinoma cell line A549 was detected by immunohistochemistry. SP and NSP cells in the cell line A549 were isolated by FACS, and their differentiation was analysed. ABCG2 expression in the two cell subsets was detected by RT-PCR. The cell growth curves, cell division indexes, cell cycles, plate clone formation tests, migration and invasion assays, chemotherapeutic susceptibility tests, tests of the intracellular drug levels, and the tumor cell implantation experiments on nude mice were applied to study the biological properties of the two cell subsets. The expression of ABCG2 in the transplanted tumor in nude mice was detected by immunohistochemistry and RT-PCR. RESULTS: The positive rate of ABCG2 expression in the A549 cells by immunohistochemistry was 2.13%. SP and NSP cells were isolated by FACS. The SP cells could produce both SP and NSP cells, while NSP cells only produced NSP cells. SP cells expressed ABCG2, but NSP cells did not. The proliferation and migration abilities of the two cell subsets were similar, but the invasion and tumorigenic ability of SP cells was significantly higher than that of NSP cells. The susceptibilities to DDP and its intracellular levels of the two cell subsets were similar, but the susceptibilities to 5-FU, VP16, NVB and GEM and their intracellular levels of NSP cells were significantly higher than those of the SP cells. CONCLUSIONS: SP cells in the human lung adenocarcinomas cell line A549 is enriched with tumor stem cells. An effective way to get lung adenocarcinomas stem cells is to isolate SP cells by FACS.