IL6 and prostate cancer: PCA: prostate cancer, ROS: reactive oxygen species, SCFA: short-chain fatty acid, IL6: interleukin-6, STAT3: signal transducer and activator of the transcription-3, LPS: lipopolysaccharide, LNCaP: lymph node carcinoma of the prostate, LAPC4: Los Angeles prostate cancer 4, AR: androgen receptor