Loss of annexin A1 disrupts normal prostate glandular structure by inducing autocrine IL-6 signaling.
Annexin A1 (ANXA1) expression is commonly reduced in premalignant lesions and prostate cancer, but a causal relationship of ANAX1 loss with carcinogenesis has not been established. ANXA1 levels have been shown to inversely correlate with interleukin 6 (IL-6) expression in other cell types and IL-6 has been suggested to enhance prostate cancer initiation and promotion. To investigate whether loss of ANXA1 may contribute to prostate carcinogenesis, ANXA1 expression was reduced using RNA interference in non-tumorigenic human prostatic epithelial cells (RWPE-1/rA1). No effect on morphology, apoptosis, migration or anchorage-dependent or -independent growth was detected. However, IL-6 mRNA and secreted protein levels were elevated in RWPE-1/rA1 cells. In addition, re-expression of ANXA1 in these cells suppressed IL-6 secretion, and altering ANXA1 levels in prostate cancer cells had similar effects on IL-6. The effects of ANXA1 loss and increased IL-6 expression on prostate epithelium were examined using an assay of acinar morphogenesis in vitro. Acini formed by RWPE-1/rA1 cells had delayed luminal clearing and larger mean diameters than control cells. The RWPE-1/rA1 phenotype was recapitulated by treating control cells with recombinant IL-6 and was reversed in RWPE-1/rA1 cells by blocking IL-6 bioactivity. Taken together, these data support a direct role for decreased ANXA1 expression in prostate carcinogenesis and enhancing tumor aggressiveness via the upregulation of IL-6 expression and activity.
Inokuchi
Junichi
J
Department of Urology, University of California, Irvine, Orange, CA 92868, USA.
Lau
Alice
A
Tyson
Darren R
DR
Ornstein
David K
DK
D017305:Annexin A1 / Q000502:physiology*; D019898:Autocrine Communication; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000378:metabolism* / Q000473:pathology; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000502:physiology*; D008297:Male; D011467:Prostate / Q000378:metabolism / Q000473:pathology; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D015854:Up-Regulation
D017305:Annexin A1; D015850:Interleukin-6