Dendrimer conjugated estramustine nanocrystalline 'Dendot': An effective inhibitor of DMBA-TPA induced papilloma formation in mouse

Eur J Pharm Sci. 2017 Nov 15;109:316-323. doi: 10.1016/j.ejps.2017.08.026. Epub 2017 Aug 23.


Clinically approved anticancer drug estramustine mediates its function by impairing microtubule polymerization. However, the low aqueous solubility and high toxicity limit its anticancer activity via the oral route. Previously, efforts have been made to develop an enhanced water soluble form of estramustine as estramustine phosphate (EM) but acidic gastrointestinal pH breaks the phosphate derivative via oral administration. As an alternative approach, we have made an effort to enhance solubility and minimize toxicity in vivo by conjugating EM to a poly(amidoamine) (PAMAM) dendrimer, which generated the sustained release of dendrimer conjugate (DEM). To the best of our knowledge, for the first time, we report the direct proof of the nano-crystalline 'DenDot' of DEM on TEM image. The toxicity study showed that both EM and DEM were nontoxic up to 20mg/kg. A comparative anti-papilloma study was also performed with EM and dendrimer conjugates (DEM) using a two-stage mouse skin carcinogenesis model. We found that DEM was more effective in inhibiting skin tumor formation than EM. Histopathology and immunohistochemistry studies further indicated that DEM treatment increased cell apoptosis, and reduced epithelial hyperplasia, cell proliferation and inflammation in skin tissues of mice. In addition, the synthetic DEM conjugate inhibited skin tumor progression more effectively than EM.

Keywords: DMBA-TPA; Dendrimer-conjugates; Immunohistochemistry; Mouse model; ‘DenDot’.

MeSH terms

  • 9,10-Dimethyl-1,2-benzanthracene
  • Animals
  • Antineoplastic Agents / administration & dosage*
  • Antineoplastic Agents / chemistry
  • Apoptosis / drug effects
  • Carcinogens
  • Cell Proliferation / drug effects
  • Dendrimers / administration & dosage*
  • Dendrimers / chemistry
  • Estramustine / administration & dosage*
  • Estramustine / chemistry
  • Female
  • Intestines / anatomy & histology
  • Intestines / drug effects
  • Kidney / anatomy & histology
  • Kidney / drug effects
  • Liver / anatomy & histology
  • Liver / drug effects
  • Mice
  • Nanoparticles / administration & dosage*
  • Nanoparticles / chemistry
  • Papilloma / chemically induced
  • Papilloma / pathology
  • Papilloma / prevention & control*
  • Skin Neoplasms / chemically induced
  • Skin Neoplasms / pathology
  • Skin Neoplasms / prevention & control*
  • Stomach / anatomy & histology
  • Stomach / drug effects
  • Tetradecanoylphorbol Acetate


  • Antineoplastic Agents
  • Carcinogens
  • Dendrimers
  • PAMAM Starburst
  • Estramustine
  • 9,10-Dimethyl-1,2-benzanthracene
  • Tetradecanoylphorbol Acetate