Potential use of alexidine dihydrochloride as an apoptosis-promoting anticancer agent

Mol Cancer Ther. 2006 Sep;5(9):2234-40. doi: 10.1158/1535-7163.MCT-06-0134.


Despite advances in surgery, radiation, and chemotherapy, novel therapeutics are needed for head and neck cancer treatment. The objective of this current study was to evaluate alexidine dihydrochloride as a novel compound lead for head and neck cancers. Using a tetrazolium-based assay, the dose required to reduce cell viability by 50% (ED50) was found to be approximately 1.8 micromol/L in FaDu (human hypopharyngeal squamous cancer) and approximately 2.6 micromol/L in C666-1 (human undifferentiated nasopharyngeal cancer) cells. In contrast, the ED50 values were much higher in untransformed cells, specifically at approximately 8.8 micromol/L in GM05757 (primary normal human fibroblast), approximately 8.9 micromol/L in HNEpC (primary normal human nasal epithelial), and approximately 19.6 micromol/L in NIH/3T3 (mouse embryonic fibroblast) cells. Alexidine dihydrochloride did not interfere with the activities of cisplatin, 5-fluorouracil, or radiation, and interacted in a less-than-additive manner. DNA content analyses and Hoechst 33342 staining revealed that this compound induced apoptosis. Alexidine dihydrochloride-induced mitochondrial damage was visualized using transmission electron microscopy. Mitochondrial membrane potential (DeltaPsiM) depolarization was detectable after only 3 hours of treatment, and was followed by cytosolic Ca2+ increase along with loss of membrane integrity/cell death. Caspase-2 and caspase-9 activities were detectable at 12 hours, caspase-8 at 24 hours, and caspase-3 at 48 hours. FaDu cell clonogenic survival was reduced to < 5% with 1 micromol/L alexidine dihydrochloride, and, correspondingly, this compound decreased the in vivo tumor-forming potential of FaDu cells. Thus, we have identified alexidine dihydrochloride as the first bisbiguanide compound with anticancer specificity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology*
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology
  • Apoptosis / drug effects*
  • Biguanides / administration & dosage
  • Biguanides / pharmacology*
  • Carcinoma, Squamous Cell / drug therapy*
  • Carcinoma, Squamous Cell / pathology
  • Caspase 2 / metabolism
  • Caspase 9 / metabolism
  • Cisplatin / administration & dosage
  • Enzyme Activation / drug effects
  • Female
  • Fluorouracil / administration & dosage
  • Humans
  • Hypopharyngeal Neoplasms / drug therapy*
  • Hypopharyngeal Neoplasms / pathology
  • Membrane Potentials / drug effects
  • Mice
  • Mice, Inbred BALB C
  • Mice, SCID
  • Mitochondrial Membranes / drug effects
  • Mitochondrial Membranes / physiology
  • NIH 3T3 Cells
  • Xenograft Model Antitumor Assays


  • Antineoplastic Agents
  • Biguanides
  • Caspase 2
  • Caspase 9
  • alexidine
  • Cisplatin
  • Fluorouracil