Upregulation of TLRs and IL-6 as a marker in human colorectal cancer

Int J Mol Sci. 2014 Dec 24;16(1):159-77. doi: 10.3390/ijms16010159.

Abstract

Toll-like receptors (TLRs) not only form an important part of the innate immune system but also serve to activate the adaptive immune system in response to cancer. Real-time PCR; immunohistochemical stain and Western blotting analyses were performed to clarify molecular alterations in colorectal cancer (CRC) patients. We identified Toll-like receptor 1 (TLR1), TLR2, TLR4 and TLR8 gene expression levels and downstream gene, i.e., interleukin-6 (IL-6), IL-8, interferon-α (IFN-α) and myeloid differentiation primary-response protein-88 (MyD88), expression levels in CRC patients and in cancer cell lines. CRC tissues have higher TLR1, TLR2, TLR4, TLR8, IL-6 and IL-8 gene expression levels than do the normal colon mucosa (p < 0.05). TLR2 expression varied in different cell types (mucosa and lymphocytes). There was no difference in the MyD88 and IFN-α gene expression levels between cancerous and normal colon mucosa. CRC patients had higher levels of IL-6 (p = 0.002) and IL-8 (p = 0.038) expression than healthy volunteers did; and higher IL-6 and IL-8 expression was also found to signify a higher risk of recurrence. CL075 (3M002) treatments can reduce the production of IL-8 in different cancer cell lines. The signaling pathway of TLRs in cancer tissue is different from that in normal cells; and is MyD88-independent. Higher expression levels of TLR1, TLR2, TLR 4 and TLR 8 mRNA were related to upregulation inflammatory cytokines IL-6 and IL-8 gene expression in tissue and to the upregulation of IL-6 in blood. The concentration of IL-6 in serum can be used as an indicator of the possibility of CRC recurrence. Treatment with 3M002 can reduce IL-6 production in vitro and may prevent CRC recurrence. Our findings provide evidence that TLR1, TLR2, TLR4 and TLR8 gene expression induce downstream IL-6 and IL-8 gene expression; detection of these expression levels can serve as a CRC marker.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Biomarkers, Tumor / genetics
  • Biomarkers, Tumor / metabolism*
  • Case-Control Studies
  • Colorectal Neoplasms / metabolism*
  • Female
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Interleukin-6 / genetics
  • Interleukin-6 / metabolism*
  • Male
  • Middle Aged
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Toll-Like Receptors / genetics
  • Toll-Like Receptors / metabolism*
  • Up-Regulation*

Substances

  • Biomarkers, Tumor
  • IL6 protein, human
  • Interleukin-6
  • RNA, Messenger
  • Toll-Like Receptors