Curcumin is widely used to impart color and flavor to food, but scientists have found that this yellow powder obtained from the roots of the turmeric plant (Curcuma longa) can also help prevent or combat stomach cancer.
The study of researchers at the Federal University of Sao Paulo (UNIFESP) and the Brazilian University of Parfum (UFPA) identified the possible therapeutic effects of this pigment and other bioactive compounds found in food on stomach cancer, the third and fifth most common cancer among Brazilian men and women, respectively.
The study is part of a Thematic Project supported by the Sao Paulo Research Foundation – FAPESP. His findings have been published in the journalEpigenomics,
"We have taken a comprehensive review of the scientific literature on all nutrients and bioactive compounds with the potential to prevent or treat stomach cancer and found that one of them is curcumin," Daniel Keirosh Kalkanho, UFPA professor and first author of the study, said.
According to Calcagno, who has conducted post-doctoral research at UNIFESP with a FAPESP scholarship, compounds such as cholecalciferol (vitamin D form), resveratrol (polyphenol) and quercetin may prevent or fight gastric cancer because they are natural regulators of histone activity.
Histones are proteins in cell nuclei that organize the double helix of DNA into structural units called nucleosomes. Each nucleosome is made of DNA wrapped around eight histone proteins (histone octamer) as a reel to compact the DNA so that it fits into the cell where it is packaged in a chromatin.
Post-translational chemical modification of the amino acid chain in these proteins, such as acetylation (methylation) or methylation (addition of the methyl group), may affect the compaction of chromatin and therefore of gene expression.
"If the histones are acetylated, for example, the chromatin will be less condensed, and a gene in the DNA segment within it will be available for expression." By contrast, if the histones are not acetylated, the chromatin will be "Condensed and the gene will not be expressed," Calgano said.
Studies carried out in recent years suggest that posttranslational modification of histones leads to changes in gene expression without affecting the DNA sequence. These epigenetic variations affect the development of various cancers.
To determine whether this hypothesis applies to stomach cancer, several groups of researchers co-ordinated by Maria de Aruda Cardoso Smith, a professor at UNIFESP, examine the models of acetylation of histones in gastric cell samples from healthy individuals and patients diagnosed with stomach cancer.
Researchers have found that cells from patients with gastric cancer show changes in the pattern of histone acetyltransferase (HATs) and histone deacetylase (HDACs) expression. These changes are epigenetic and affect the structure and integrity of the genome in many tumors, including stomach cancer.
Since recent studies also show that nutrients and bioactive compounds can regulate the activity of HATs and HDACs, scientists from UNIFESP and UFPA seek to find those that can affect the acetylation of histones and thus help prevent cancer the stomach or even treating the disease.
In addition to curcumin, other compounds found to play a key role in the modulation of histone activity are cholecalciferol, resveratrol (mainly in grape seed and red wine), quercetin (abundant in apples, broccoli and onions), garcinol (isolated from the kokum tree bark, Garcinia indica) and sodium butyrate (produced by intestinal bacteria by fermentation of dietary fiber).
"These compounds can favor activation or repression of genes involved in the development of gastric cancer by promoting or inhibiting histone acetylation," Calcagno said.
Curcumin, for example, affects histone modifications primarily by inhibiting HATs and HDACs in inhibiting cancer cell proliferation and inducing apoptosis (programmed cell death). Garcinol, whose chemical structure resembles that of curcumin, inhibits HATs and helps prevent stomach cancer by neutralizing free radicals.
"We are now planning to clarify the anti-cancer and epigenetic effects of bioactive compounds derived from Amazon plants such as acai [Euterpe oleracea] and bacon or reddish [Byrsonima crassifolia], with a view to their future use in the prevention and treatment of stomach cancer, "Calcagno said.