Objective To investigate the role and mechanism of pancreatic stellate cells (PSCs) and pancreatic cancer cells (PCCs) in the angiogenesis of pancreatic cancer.

Methods The experimental study was conducted. The human PSCs and PCCs and human umbilical vein endothelial cells (HUVECs) were cultured in vitro. HUVECs was treated with PSCs/PCCs supernatants and matrix metalloproteinase (MMP) inhibitor of different types and concentrations. As controls, HUVECs treated with complete endoprime medium (C/E) and DMEM/Ham's F12 medium (D/F) were set as the C/E group and the D/F group, respectively. Observation indicators: (1) proliferation of HUVECs under different conditions; (2) tube formation of HUVECs under different conditions; (3) migration of HUVECs under different conditions; (4) expression of MMP‑2 in the supernatants of PSCs and PCCs; (5) effect of MMP inhibitor GM6001 on migration of HUVECs. Measurement data with normal distribution were represented as Mean±SD, comparison among groups was conducted using the one way ANOVA and comparison between groups was conducted using the LSD-t test.

Results (1) Proliferation of HUVECs under different conditions. Results of HUVECs proliferation assay using 5‑ethynyl‑2′‑deoxyuridine (EdU) labeling showed that the binding rate of EdU in the HUVECs of D/F group and HUVECs treated with supernatants of different concentration (25%, 50%, 75%, 95%) of PSCs was 12.4%±1.0%, 24.5%±2.9%, 25.3%±3.0%, 22.8%±2.0%, 22.9%±2.8%, respectively, showing a significant difference among them (F=8.60, P<0.05). There were significant differences in the binding rate of EdU between HUVECs in the D/F group and HUVECs treated with supernatants of different concentration (25%, 50%, 75%, 95%) of PSCs, respectively (P<0.05). The binding rate of EdU between HUVECs in the D/F group and HUVECs treated with supernatants of different concentration (25%, 50%, 75%, 95%) of PCCs was 12.4%±1.0%, 30.0%±3.2%, 32.1%±1.0%, 32.3%±3.5%, 26.2%±5.6%, respectively, showing a significant difference among them (F=11.93, P<0.05). There were significant differences in the binding rate of EdU between HUVECs in the D/F group and HUVECs treated with supernatants of different concentration (25%, 50%, 75%, 95%) of PSCs, respectively (P<0.05). (2) Tube formation of HUVECs under different conditions. Number of tube formation, length of tube in the HUVECs of D/F group and HUVECs treated with PSCs supernatants was 15.2±2.3, (12.1±1.5)mm and 49.7±3.2, (39.8±2.3)mm, respectively, showing significant differences between the two groups of HUVECs (P<0.05). (3) Migration of HUVECs under different conditions. Results of single cell tracing experiment showed that the migration rate of HUVECs treated with supernatants of different ratio of PSCs and PCCs was faster than that of HUVECs in the D/F group, and the enhancement effect of supernatants of PSCs and PCCs was dose‑dependent. The migration rate of HUVECs treated with mix supernatants of different concentration of PSCs and PCCs and supernatants of co‑cultured PSCs and PCCs was faster than that of HUVECs in the D/F group. The migration rate of HUVECs treated supernatants of co‑cultured PSCs and PCCs was faster than that of HUVECs treated with mix supernatants of different concentration of PSCs and PCCs, showing a synergistic effect in the HUVECs treated supernatants of co‑cultured PSCs and PCCs. (4) Expression of MMP‑2 in the supernatants of PSCs and PCCs. Results of gelatine zymography showed that the MMP‑2 expression levels decreased sequentially in super-natants of co‑cultured PSCs and PCCs, supernatants of PSCs, mix supernatants of PSCs and PCCs and supernatants PCCs. (5) Effect of MMP inhibitor GM6001 on migration of HUVECs. Results of single cell tracing experiment showed that the migration rate of HUVECs treated with PSCs supernatants combined with different concentration of GM6001 (0, 1, 10, 25 μmol/L) was (25.70±2.06)μm/h, (18.37±1.61)μm/h, (16.20±0.26)μm/h, (15.99±0.58)μm/h, respectively, showing a significant difference among them (F=11.39, P<0.05). There were significant differences in the migration rate between HUVECs treated with PSCs supernatants combined with 1, 10, 25 μmol/L GM6001 and HUVECs treated with PSCs supernatants (P<0.05). The migration rate of HUVECs treated with mix super-natants of PSCs and PCCs combined with different concentration of GM6001 (0, 1, 10, 25 μmol/L) was (30.06±3.70)μm/h, (22.76±1.56)μm/h, (23.87±2.84)μm/h, (22.10±2.35)μm/h, respectively, showing a significant difference among them (F=4.06, P<0.05). There were significant differences in the migration rate between HUVECs treated with mix supernatants of PSCs and PCCs combined with 1, 10, 25 μmol/L GM6001 and HUVECs treated with mix supernatants of PSCs and PCCs (P<0.05).

Conclusions Both PSCs and PCCs can promote the proliferation, migration and angiogenesis of HUVECs in vitro experiment. Releasing of MMP‑2 by interaction between PSCs and PCCs is an important factor to stimulate endothelial cell migration, which increases the stimulating activity of angiogenesis, especially the migration ability of HUVECs.