Mechanism of SPARC-enhanced chemosensitivity of pancreatic cancer cells to gemcitabine / 中华肿瘤杂志

ABSTRACT

<p><b>OBJECTIVE</b>The aim of this study was to explore the effect of SPARC on the anti-cancer effect of gemcitabine and underlying mechanism in pancreatic cancer.</p><p><b>METHODS</b>After treating with gemcitabine, the proliferation rate of MIA PaCa2, MIA PaCa2/V and MIA PaCa2/SPARC69 cells was detected by MTT assay. The cell cycle distribution and cell apoptosis in each group were examined by flow cytometry, and the capability of clone formation was tested by adhesion-dependent clone formation assay. The apoptosis-related proteins were analyzed by Western blot.</p><p><b>RESULTS</b>The growth of pancreatic cancer cells was inhibited by gemcitabine in a time-dependent and dose-dependent manner. Its IC50 at 24, 48, and 72-h was (40.1 ± 2.5) µmol/L, (15.0 ± 0.5) µmol/L and (6.6 ± 0.1) µmol/L, respectively. The overexpression of SPARC increased the inhibitory effect of gemcitabine on growth of pancreatic cancer MIA PaCa2/SPARC69 cells, presenting a dose- and time- dependent manner. Its IC50 at 24, 48, 72 h was (24.3 ± 1.5) µmol/L, (7.7 ± 0.3) µmol/L and (4.8 ± 0.2) µmol/L, respectively. The clone formation assay showed that before gemcitabine treatment, the clone numbers of MIA PaCa2, MIA PaCa2/V and MIA PaCa2/SPARC69 cells were (2350 ± 125), (2130 ± 120) and (1567 ± 11), respectively. After gemcitabine treatment, the clone numbers of MIA PaCa2, MIA PaCa2/V and MIA PaCa2/SPARC69 cells were ( 1674 ± 79) , (1587 ± 94) and (557 ± 61), respectively. The overexpression of SPARC enhanced the chemosensitivity of MIA PaCa2 cells to gemcitabine chemotherapy. After treating with 10 µmol/L gemcitabine for 48 h, the ratio of G0/G1 cells in MIA PaCa2, MIA PaCa2/V and MIA PaCa2/SPARC69 cells were (56.0 ± 5.5)%, (55.0 ± 4.5)% and (68.0 ± 7.0)%, respectively. The cells arrested at G0/G1 phase were significantly increased in the MIA PaCa2/SPARC69 cells. The apoptosis rates of MIA PaCa2, MIA PaCa2/V and MIA PaCa2/SPARC69 cells were (22.4 ± 2.5)%, (19.9 ± 2.0)% and (37.7 ± 3.9)%, respectively, indicating that overexpression of SPARC enhanced the gemcitabine-induced apoptosis in MIA PaCa2 cells. The Western blot analysis showed that, compared with MIA PaCa2 and MIA PaCa2/V cells, the expression of caspase-2, -8, -9 and cleaved PARP protein was significantly increased, while the expression of Bcl-2 was not changed significantly in the MIA PaCa2/SPARC69 cells.</p><p><b>CONCLUSION</b>SPARC can enhance the chemosensitivity of pancreatic cancer cells to gemcitabine via regulating the expression of apoptosis-related proteins.</p>