The effect of different levels of dietary ß‐carotene on DMBA‐induced salivary gland tumors

Abstract

Different levels of beta-carotene (0, 5, 25, 125, and 250 mg/kg diet) were tested for their chemoprevention effects using 9,10-dimethyl-1,2-benzanthracene-induced salivary gland tumor model in rats. Tumor incidence and tumor weights were slightly lower in rats fed diets supplemented with 25 mg or more beta-carotene/kg diet. Hepatic vitamin A and beta-carotene levels were increased in a dose-dependent fashion, reaching a plateau at 125 mg beta-carotene/kg diet. In plasma, beta-carotene concentrations were also increased with an increase in dietary beta-carotene. Vitamin A levels in plasma were not affected. The normal salivary glands had higher concentrations of beta-carotene than did the tumors. The results suggest that the decreases in tumor incidence and tumor weight may be related to the increase in plasma and tissue levels of beta-carotene as a result of feeding high levels of beta-carotene.

The Transduction of Rat Submandibular Glands by an Adenoviral Vector Carrying the Human Growth Hormone Gene is Associated with Limited and Reversible Changes at the Infusion Site

“…There are reports of salivary gland neoplasms in rats, such as squamous cell carcinoma, that result from ionizing radiation (Glucksmann and Cherry, 1976) or by compounds such as potassium iodide (Takegawa et al, 1998) and 7,12-dimethlbenz[a]anthracene (DMBA) (Alam and Alam, 1987). Squamous metaplasia of the ductular epithelium, considered a preneoplastic condition, typically precedes salivary gland neoplasia.…”

Vitamin A Deficiency and Immunity.

“…Retinoids in vivo were shown to prevent induction or growth of chemically induced tumors [80][81][82]. Retinoic acid in mice stimulated cytotoxic T lymphocytes rather than natural killer (NK) cell activity [83,84].…”

Modulatory effects of snuff, retinoic acid, andß‐carotene on DMBA‐induced hamster cheek pouch carcinogenesis in relation to keratin expression

“…In rodents, normal hepatic vitamin A levels ranged between 50 and 70 /¿g/g, whereas in plasma the levels were from 50 to 60 fig/dl. /3-Carotene levels were not detected either in plasma or in liver (26,27). However, supplementation of the diet with ß-carotene results in an increase in plasma and tissue levels of vitamin A and /?-carotene, which decreased the tumor incidence (26,27).…”

“…/3-Carotene levels were not detected either in plasma or in liver (26,27). However, supplementation of the diet with ß-carotene results in an increase in plasma and tissue levels of vitamin A and /?-carotene, which decreased the tumor incidence (26,27). Recently, Schwartz and others (28) showed that /3-carotene could induce regression of well-established carcinomas of HCP when injected locally into the tumor-bearing cheek pouch.…”