Calebin A Potentiates the Effect of 5-FU and TNF-β (Lymphotoxin α) against Human Colorectal Cancer Cells: Potential Role of NF-κB

Int J Mol Sci. 2020 Mar 31;21(7):2393. doi: 10.3390/ijms21072393.


Objective: The majority of chemotherapeutic agents stimulate NF-κB signaling that mediates cell survival, proliferation and metastasis. The natural turmeric non-curcuminoid derivate Calebin A has been shown to suppress cell growth, invasion and colony formation in colorectal cancer cells (CRC) by suppression of NF-κB signaling. Therefore, we hypothesized here that Calebin A might chemosensitize the TNF-β-treated tumor cells and potentiates the effect of 5-Fluorouracil (5-FU) in advanced CRC.

Materials and methods: CRC cells (HCT116) and their clonogenic 5-FU chemoresistant counterparts (HCT116R) were cultured in monolayer or alginate-based 3D tumor environment culture and were treated with/without Calebin A, TNF-β, 5-FU, BMS-345541 and DTT (dithiothreitol).

Results: The results showed that TNF-β increased proliferation, invasion and resistance to apoptosis in chemoresistant CRC cells. Pretreatment with Calebin A significantly chemosensitized HCT116R to 5-FU and inhibited the TNF-β-induced enhanced efforts for survival, invasion and anti-apoptotic effects. We found further that Calebin A significantly suppressed TNF-β-induced phosphorylation and nuclear translocation of p65-NF-κB, similar to BMS-345541 (specific IKK inhibitor) and NF-κB-induced tumor-promoting biomarkers (NF-κB, β1-Integrin, MMP-9, CXCR4, Ki67). This was associated with increased apoptosis in HCT116 and HCT116R cells. Furthermore, blocking of p65-NF-κB stimulation by Calebin A was imparted through the downmodulation of p65-NF-κB binding to the DNA and this suppression was turned by DTT.

Conclusion: Our findings indicate, for the first time, that Calebin A chemosensitizes human CRC cells to chemotherapy by targeting of the p65-NF-κB signaling pathway.

Keywords: 5-Fluorouracil; Calebin A; NF-κB; TNF-β (lymphotoxin); chemosensitization; colorectal cancer.

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Apoptosis / drug effects
  • Biomarkers, Tumor / metabolism
  • Cell Line
  • Cell Proliferation / drug effects
  • Cell Survival
  • Cinnamates / metabolism*
  • Cinnamates / pharmacology
  • Colonic Neoplasms / metabolism*
  • Colonic Neoplasms / pathology
  • Colorectal Neoplasms / metabolism*
  • Colorectal Neoplasms / pathology
  • Fluorouracil / metabolism*
  • Fluorouracil / pharmacology
  • Humans
  • Lymphotoxin-alpha / metabolism*
  • Lymphotoxin-alpha / pharmacology
  • Monoterpenes / metabolism*
  • NF-kappa B / metabolism
  • Phosphorylation
  • Signal Transduction / drug effects
  • Transcription Factor RelA / metabolism


  • Antineoplastic Agents
  • Biomarkers, Tumor
  • Cinnamates
  • Lymphotoxin-alpha
  • Monoterpenes
  • NF-kappa B
  • RELA protein, human
  • Transcription Factor RelA
  • calebin-A
  • Fluorouracil