Abstract
Aim: To investigate Fusobacterium nucleatum (F. nucleatum) abundance in colorectal cancer (CRC) tissues and its association with CRC invasiveness in Chinese patients. Methods: The resected cancer and adjacent normal tissues (10 cm beyond cancer margins) from 101 consecutive patients with CRC were collected. Fluorescent quantitative polymerase chain reaction (FQ-PCR) was applied to detect F. nucleatum in CRC and normal tissues. The difference of F. nucleatum abundance between cancer and normal tissues and the relationship of F. nucleatum abundance with clinical variables were evaluated. Fluorescence in situ hybridization (FISH) analysis was performed on 22 CRC tissues with the highest F. nucleatum abundance by FQ-PCR testing to confirm FQ-PCR results. Results: The median abundance of F. nucleatum in CRC tissues [0.242 (0.178-0.276)] was significantly higher than that in normal controls [0.050 (0.023-0.067)] (P < 0.001). F. nucleatum was over-represented in 88/101 (87.1%) CRC samples. The abundance of F. nucleatum determined by 2(-ΔCT) was significantly greater in tumor samples [0.242 (0.178, 0.276)] than in normal controls [0.050 (0.023, 0.067)] (P < 0.001). The frequency of patients with lymph node metastases was higher in the over-abundance group [52/88 (59.1%)] than in the under-abundance group [0/13 (0%)] (P < 0.005). No significant association of F. nucleatum with other clinico-pathological variables was observed (P > 0.05). FISH analysis also found more F. nucleatum in CRC than in normal tissues (median number 6, 25(th) 3, 75(th) 10 vs 2, 25(th) 1, 75(th) 5) (P < 0.01). Conclusion: F. nucleatum was enriched in CRC tissues and associated with CRC development and metastasis.