Dietary
polyphenols, including
anthocyanidins and their
glycosides anthocyanins, are suggested to be involved in the protective effects of fruits and vegetables against
cancer. Very few data are available concerning the effects of
anthocyanidins/
anthocyanins on cellular processes induced by
growth factors such as
neurotensin and
epidermal growth factor (
EGF), which are implicated in the pathophysiology of
colon cancer. Here, we show that
neurotensin and
EGF caused an increase in the extracellular acidification rate, which could reflect the activity of cellular metabolism, in the human
carcinoma cell line HT29 clone 19A.
Neurotensin and
EGF also caused a strong rise in the intracellular Ca2+ concentration, induced phosphorylation of
extracellular signal-regulated kinases (ERK1 and ERK2), and stimulated growth of human
carcinoma cells.
Cyanidin (10 microM), but not its
glycosides cyanin and idaein, was able to inhibit the
neurotensin- and
EGF-induced increased rate of extracellular acidification. In contrast to N-ethyl-N-isopropyl
amiloride, an inhibitor of Na+/H+ exchange,
cyanidin did not alter the rate of intracellular pH recovery of cells loaded by NH3/NH4+, indicating that
cyanidin inhibits cellular metabolism, rather than directly altering Na+/H+ exchange.
Cyanidin, but not cyanin and idaein, was able to inhibit an increase in intracellular Ca2+ concentration induced by
neurotensin.
Neurotensin- and
EGF-induced phosphorylation of ERKs was not affected by
cyanidin, cyanin, and idaein at < or = 100 microM. Only
cyanidin (100 microM), but not cyanin and idaein, was able to inhibit cellular growth induced by
EGF. Thus these findings suggest that a dietary
polyphenol cyanidin, but not its
glycosides, is a potent inhibitor of
mitogen-induced metabolic activity, increase in free intracellular Ca2+, and cellular growth of cultured colon
carcinoma cells.