Gallotannin (Penta-O-Galloyl-beta-D-glucose) against Breast Cancer

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>> Friday, September 10, 2010

Breast cancer awareness

Breast cancer (BCa) is one of the major causes of cancer-related deaths in women. Most of BCa express estrogen receptors (ER) and/or progesterone receptors, and some have amplified human epidermal growth factor receptor (HER-2) proto-oncogene and express high levels of the HER-2 protein. In some cases, BCa lacks all these expressions referred as “triple negative BCa”. This subtype is clinically characterized as more aggressive and less responsive to standard treatment and associated poorer overall patient prognosis.

Various drugs like BSI 201 and SN-38 are in clinical trials for the treatment of triple negative BCa.

Iniparib, SN-38BSI 201, also called as Iniparib is 4-iodo-3-nitrobenzamide. It inhibits the nuclear enzyme poly ADP ribose polymerase (PARP), which is involved in multiple cellular processes, including DNA repair. SN-38 is an active metabolite of irinotecan.

Penta-O-galloyl-beta-D-glucoseRecently, Penta-1, 2, 3, 4, 6-O-galloyl-beta-D-glucose (PGG), naturally occurring gallotannin polyphenolic compound found in oriental herbs was reported to have significant inhibitory activity on BCa cells especially triple negative BCa cells both in vitro and in vivo.
In this study, PGG treatment (in cell culture) caused P53-ser15 phosphorylation and caspase-mediated apoptosis in MCF-7 BCa cells. In P53-mutant MDA-MB231 triple negative BCa cells, PGG caused not only apoptosis, but also autophagic responses. Independent of P53 or ERĪ± status of the BCa cells, PGG induced S-arrest and G1 arrest. There was no induction of P21cip1 and P27kip1 expression. Downregulation of Cyclin D1 by PGG has been an important mediating event for the G1 arrest action.
In vivo study showed that PGG given by oral administration was quite safe to the host nude mice and had greater than 60% inhibition of a triple negative BCa (MDA-MB231) xenograft model.
MDA-MB231 was injected subcutaneously into the right flank of athymic nude mice. After 4 days, PGG was delivered by oral gavage at the dose of 20 mg/kg body weight.


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