Dietary phytoestrogens and cancer: in vitro and in vivo studies

Thirty postmenopausal women (11 omnivores, 10 vegetarians and 9 apparently healthy women with surgically removed breast cancer) were investigated with regard to the association of their urinary excretion of estrogens, lignans and isoflavonoids (all diphenols) with plasma sex hormone binding globulin (SHBG). A statistically significant positive correlation between urinary total diphenol excretion and plasma SHBG was found which remained statistically significant after elimination of the confounding effect of body mass determined by body mass index (BMI). Furthermore we found a statistically significant negative correlation between plasma SHBG and urinary excretion of 16α-hydroxyestrone and estriol which also remained significant after eliminating the effect of BMI. Furthermore we observed that enterolactone (Enl) stimulates the synthesis of SHBG by HepG2 liver cancer cells in culture acting synergistically with estradiol and at physiological concentrations. Enl was rapidly conjugated by the liver cells, mainly to its monosulfate. Several lignans and the isoflavonoids daidzein and equol were found to compete with estradiol for binding to the rat uterine type II estrogen binding site (the s.c. bioflavonoid receptor). It is suggested that lignans and isoflavonoids may affect uptake and metabolism of sex hormones by participating in the regulation of plasma SHBG levels and in this way influence their biological activity and that they may inhibit cancer cell growth like some flavonoids by competing with estradiol for the type II estrogen binding sites.     

Diet and urinary estrogen profile in premenopausal omnivorous and vegetarian women and in premenopausal women with breast cancer

The urinary estrogen profile was studied in the midfollicular phase twice, and diet four times during 1 yr in 10 premenopausal breast cancer (BC) patients consuming an omnivorous normal Finnish diet and in two control groups, one consuming an omnivorous (n = 12) and the other a lactovegetarian (n = 11) diet. Total fat intake in relation to caloric intake was almost identical in all three groups. Only with regard to grain fiber intake did the BC patients differ significantly from both other groups. No differences were found between the groups with regard to urinary excretion of 13 individual estrogens and total estrogens, with the exception of 4-hydroxyestrone (4-OH-E1), which was significantly lower (P less than 0.05) in the BC group than in the vegetarians. A high carbohydrate to protein ratio in the diet had a negative correlation with the excretion of 2-hydroxyestrogens and 2-hydroxyesterone (2-OH-E1) to 4-OH-E1 ratio. The BC group had significantly higher urinary 2-OH-E1 to E1 ratio (P less than 0.05) compared to the vegetarians. The 2-OH-E1 to 4-OH-E1 ratio was highest in the BC group (= 7.1) and differed significantly from that of the omnivores (= 4.3; P less than 0.02) and vegetarians (= 3.6; P less than 0.005). This ratio showed a negative correlation with intake of carbohydrates, starch, total and grain fiber. Urinary excretion of 4-OH-E1 correlated positively with total and grain fiber intake and plasma SHBG. Protein intake correlated positively with urinary 2-methoxy-E1 excretion, and retinol intake positively with catechol estrogen, E1 and E2 excretion. It is concluded that estrogen production and urinary estrogen profile in premenopausal breast cancer patients is normal with the exception of a low 4-OH-E1 excretion and high urinary 2-OH-E1 to 4-OH-E1 ratio. This ratio, which seems to depend on diet, is the only urinary estrogen parameter separating premenopausal BC patients from the control omnivorous and lactovegetarian women.     

Effect of spatial connectivity on host resistance in a highly fragmented natural pathosystem

Both theory and experimental evolution studies predict migration to influence the outcome of antagonistic coevolution between hosts and their parasites, with higher migration rates leading to increased diversity and evolutionary potential. Migration rates are expected to vary in spatially structured natural pathosystems, yet how spatial structure generates variation in coevolutionary trajectories across populations occupying the same landscape has not been tested. Here, we studied the effect of spatial connectivity on host evolutionary potential in a natural pathosystem characterized by a stable Plantago lanceolata host network and a highly dynamic Podosphaera plantaginis parasite metapopulation. We designed a large inoculation experiment to test resistance of five isolated and five well‐connected host populations against sympatric and allopatric pathogen strains, over 4 years. Contrary to our expectations, we did not find consistently higher resistance against sympatric pathogen strains in the well‐connected populations. Instead, host local adaptation varied considerably among populations and through time with greater fluctuations observed in the well‐connected populations. Jointly, our results suggest that in populations where pathogens have successfully established, they have the upper hand in the coevolutionary arms race, but hosts may be better able to respond to pathogen‐imposed selection in the well‐connected than in the isolated populations. Hence, the ongoing and extensive fragmentation of natural habitats may increase vulnerability to diseases.     

Effect of dietary components, including lignans and phytoestrogens, on enterohepatic circulation and liver metabolism of estrogens and on sex hormone binding globulin (SHBG)

A brief account of our present knowledge on the enterohepatic metabolism of estrogens and on the origin, metabolism and biological effects of mammalian lignans and phytoestrogens is undertaken. Furthermore, recently published results on the effects of dietary fiber, fat and carbohydrates on estrogen metabolism are reviewed. New preliminary results are presented on quantitative assays of lignans and phytoestrogens in urine of women belonging to various dietary and population groups and in a group of chimpanzees. The highest values of lignans and phytoestrogens were found in the non-human primates, and in macrobiotic, lactovegetarian and Japanese women, all groups considered having a low risk for the development of breast and other hormone-dependent cancer. New results on correlations between intake of various fibers, lignan and phytoestrogen excretion and plasma levels of estrogens, free testosterone and SHBG in women are presented. There is a significant positive correlation between the intake of fiber and urinary excretion of lignans and phytoestrogens, and the concentration of plasma SHBG. Fiber intake and urinary excretion of lignans and equol correlated negatively with plasma percentage free estradiol. Enterolactone excretion correlated negatively with plasma free testosterone. It is concluded that dietary macro- and micronutrients seem to play an important role in estrogen metabolism.     

Chlorpromazine and apigenin reduce adenovirus replication and decrease replication associated toxicity

BACKGROUND: Adenoviruses can cause severe toxicity in immunocompromised individuals. Although clinical trials have confirmed the potency and safety of selectively oncolytic adenoviruses for treatment of advanced cancers, increasingly effective agents could result in more toxicity and therefore it would be useful if replication could be abrogated if necessary. METHODS: We analyzed the effect of chlorpromazine, an inhibitor of clathrin-dependent endocytosis and apigenin, a cell cycle regulator, on adenovirus replication and toxicity. First, we evaluated the in vitro replication of a tumor targeted Rb-p16 pathway selective oncolytic adenovirus (Ad5/3-Delta24) and a wild-type adenovirus in normal cells, fresh liver samples and in ovarian cancer cell lines. Further, we analyzed the in vitro cell killing efficacy of adenoviruses in the presence and absence of the substances. Moreover, the effect on in vivo efficacy, replication and liver toxicity of the adenoviruses was evaluated. RESULTS: We demonstrate in vitro and in vivo reduction of adenovirus replication and associated toxicity with chlorpromazine and apigenin. Effective doses were well within what would be predicted safe in humans. CONCLUSIONS: Chlorpromazine and apigenin might reduce the replication of adenovirus, which could provide a safety switch in case replication-associated side effects are encountered in patients. In addition, these substances could be useful for the treatment of systemic adenoviral infections in immunosuppressed patients.     

Dietary phytoestrogens and cancer: in vitro and in vivo studies.

Thirty postmenopausal women (11 omnivores, 10 vegetarians and 9 apparently healthy women with surgically removed breast cancer) were investigated with regard to the association of their urinary excretion of estrogens, lignans and isoflavonoids (all diphenols) with plasma sex hormone binding globulin (SHBG). A statistically significant positive correlation between urinary total diphenol excretion and plasma SHBG was found which remained statistically significant after elimination of the confounding effect of body mass determined by body mass index (BMI). Furthermore we found a statistically significant negative correlation between plasma SHBG and urinary excretion of 16-hydroxyestrone and estriol which also remained significant after eliminating the effect of BMI. Furthermore we observed that enterolactone (Enl) stimulates the synthesis of SHBG by HepG2 liver cancer cells in culture acting synergistically with estradiol and at physiological concentrations. Enl was rapidly conjugated by the liver cells, mainly to its monosulfate. Several lignans and the isoflavonoids daidzein and equol were found to compete with estradiol for binding to the rat uterine type II estrogen binding site (the s.c. bioflavonoid receptor). It is suggested that lignans and isoflavonoids may affect uptake and metabolism of sex hormones by participating in the regulation of plasma SHBG levels and in this way influence their biological activity and that they may inhibit cancer cell growth like some flavonoids by competing with estradiol for the type II estrogen binding sites.     

LCAT facilitates transacylation of 17 beta-estradiol in the presence of HDL3 subfraction

It has been shown that estrogens need to be metabolized to their hydrophobic estrogen ester derivatives to act as antioxidants in lipoproteins. Data suggest that 17beta-estradiol (E(2)) becomes esterified in LCAT-induced reactions and the esters are transported from HDL particles to LDL and VLDL particles by a CETP-dependent mechanism. In the present study we have further investigated the regulation of E(2) esterification by LCAT and focused on the importance of HDL structure and composition in the esterification process. Isolated LDL, HDL(2), HDL(3), and reconstituted discoidal HDL (rHDL) were incubated with labeled E(2), with and without purified LCAT, at 37 degrees C for 24 h. After purification of the lipoprotein fractions, there was a significant peak of radioactivity representing esterified estradiol attached to HDL(3) and rHDL, but HDL(2) and LDL contained only trace amounts of labeled estradiol ester. TLC analysis confirmed that the radioactivity migrated in a position corresponding to that of 17beta-E(2) 17-monoester standard. The amount of radioactivity associated with HDL(3) and rHDL representing esterified E(2) was significantly increased by addition of purified LCAT. However, only limited increases of radioactivity were observed in HDL(2) and LDL. In conclusion, HDL subfractions differ in their potential to regulate estradiol esterification by LCAT.