Background: Obesity is a risk factor for prostate cancer development, but the underlying mechanism is unknown. The present study tested the hypothesis that stromal cells of the adipose tissue might be recruited by cancer cells to help tumor growth.
Methods: PC3 prostate cancer cells were transplanted into the subcutaneous space of the right flank of athymic mice. One week later, adipose tissue-derived stromal or stem cells (ADSC) or phosphate-buffered saline (PBS, as control) was transplanted similarly to the left flank. Tumor size was monitored for the next 34 days; afterwards, the mice were sacrificed and their tumors harvested for histological examination. The ability of PC3 cells to attract ADSC was tested by migration assay. The involvement of the CXCL12/CXCR4 axis was tested by migration assay in the presence of a specific inhibitor AMD3100.
Results: Throughout the entire course, the average size of PC3 tumors in ADSC-treated mice was larger than in PBS-treated mice. ADSC were identified inside the tumors of ADSC-treated mice; CXCR4 expression was also detected. Migration assay indicated the involvement of the CXCL12/CXCR4 axis in the migration of ADSC toward PC3 cells. Capillary density was twice as high in the tumors of ADSC-treated mice than in the tumors of PBS-treated mice. VEGF expression was similar but FGF2 expression was significantly higher in tumors of ADSC-treated mice than in the tumors of PBS-tread mice.
Conclusion: Prostate cancer cells recruited ADSC by the CXCL12/CXCR4 axis. ADSC helps tumor growth by increasing tumor vascularity, and which was mediated by FGF2.