An Olive Leaf Extract Rich in Polyphenols Promotes Apoptosis in Cervical Cancer Cells by Upregulating p21Cip/WAF1 Gene Expression

Nutr Cancer. 2019;71(2):320-333. doi: 10.1080/01635581.2018.1559934. Epub 2019 Jan 19.

Abstract

Most of the common drugs used to treat the cervical cancer, which main etiological factor is the HPV infection, cause side effects and intrinsic/acquired resistance to chemotherapy. In this study we investigated whether an olive leaf extract (OLE), rich in polyphenols, was able to exert anti-tumor effects in human cervical cancer cells (HeLa). MTT assay results showed a reduction of HeLa cells viability OLE-induced, concomitantly with a gene and protein down-regulation of Cyclin-D1 and an up-regulation of p21, triggering intrinsic apoptosis. OLE reduced NFkB nuclear translocation, which constitutive activation, stimulated by HPV-oncoproteins, promotes cancer progression and functional studies revealed that OLE activated p21Cip/WAF1 in a transcriptional-dependent-manner, by reducing the nuclear recruitment of NFkB on its responsive elements. Furthermore, OLE treatment counteracted epithelial-to-mesenchymal-transition and inhibited anchorage-dependent and -independent cell growth EGF-induced. Finally, MTT assay results revealed that OLE plus Cisplatin strengthened the reduction of cells viability Cisplatin-induced, as OLE inhibited NFkB, AkT and MAPK pathways, all involved in Cisplatin chemoresistance. In conclusion, we demonstrated that in HeLa cells OLE exerts pro-apoptotic effects, elucidating the molecular mechanism and that OLE could mitigate Cisplatin chemoresistance. Further studies are needed to explore the potential coadiuvant use of OLE for cervical cancer treatment.

MeSH terms

  • Antineoplastic Agents, Phytogenic / pharmacology*
  • Apoptosis / drug effects
  • Cell Proliferation / drug effects
  • Female
  • Gene Expression / drug effects
  • HeLa Cells
  • Humans
  • Olea / chemistry*
  • Plant Extracts / pharmacology*
  • Polyphenols / pharmacology*
  • Up-Regulation / drug effects
  • Uterine Cervical Neoplasms / drug therapy*
  • Uterine Cervical Neoplasms / genetics
  • Uterine Cervical Neoplasms / metabolism
  • Uterine Cervical Neoplasms / pathology
  • p21-Activated Kinases / metabolism*

Substances

  • Antineoplastic Agents, Phytogenic
  • Plant Extracts
  • Polyphenols
  • PAK2 protein, human
  • p21-Activated Kinases