Showing papers by "Roberto Fabiani published in 2016"

Anti-cancer properties of olive oil secoiridoid phenols: a systematic review of in vivo studies

Abstract: Epidemiological studies suggest that olive oil intake is associated to a reduced risk of cancer. Recently, the chemopreventive activity of olive oil has been attributed to its unique phenolic compounds represented by phenolic alcohols, hydroxytyrosol (3,4-dihydroxyphenylethanol: 3,4-DHPEA) and tyrosol (p-hydroxyphenylethanol: p-HPEA), and their secoiridoid derivatives 3,4-DHPEA-EA (oleuropein aglycon), p-HPEA-EA (ligstroside aglycon), 3,4-DHPEA-EDA, p-HPEA-EDA (oleocanthal), and oleuropein. Several studies have demonstrated that these compounds are able to inhibit proliferation and induce apoptosis in different tumor cell lines. These in vitro effects have been recently summarized in several reviews. The aim of this systematic review was to evaluate the in vivo anti-cancer activities of secoiridoid phenols as evidenced by either animal models of carcinogenesis or human intervention trials. From the literature research through “PubMed” and “Web of Science”, 16 animal studies and 5 human intervention trials were identified and included in the review. Most of the animal studies have confirmed the ability of these compounds to inhibit the carcinogenesis process at both initiation and promotion/progression phases. All human intervention trials have investigated the effects of olive oil phenols on DNA damage. Among the five selected studies, three have shown a significant preventive effect on oxidative DNA damage in terms of reduction of 8-oxo-7,8-dihydro-2′-deoxyguanosine in urine, in mitochondria DNA of mononuclear cells and in lymphocyte DNA. The other two studies failed to see an effect on the urinary excretion of either etheno–DNA adducts or oxidation products of guanine. Further investigations are necessary to clarify the real chemopreventive potential of olive oil secoiridoid phenols on humans performing intervention studies on populations at high cancer risk.

A Western Dietary Pattern Increases Prostate Cancer Risk: A Systematic Review and Meta-Analysis.

Abstract: Dietary patterns were recently applied to examine the relationship between eating habits and prostate cancer (PC) risk. While the associations between PC risk with the glycemic index and Mediterranean score have been reviewed, no meta-analysis is currently available on dietary patterns defined by “a posteriori” methods. A literature search was carried out (PubMed, Web of Science) to identify studies reporting the relationship between dietary patterns and PC risk. Relevant dietary patterns were selected and the risks estimated were calculated by a random-effect model. Multivariable-adjusted odds ratios (ORs), for a first-percentile increase in dietary pattern score, were combined by a dose-response meta-analysis. Twelve observational studies were included in the meta-analysis which identified a “Healthy pattern” and a “Western pattern”. The Healthy pattern was not related to PC risk (OR = 0.96; 95% confidence interval (CI): 0.88–1.04) while the Western pattern significantly increased it (OR = 1.34; 95% CI: 1.08–1.65). In addition, the “Carbohydrate pattern”, which was analyzed in four articles, was positively associated with a higher PC risk (OR = 1.64; 95% CI: 1.35–2.00). A significant linear trend between the Western (p = 0.011) pattern, the Carbohydrate (p = 0.005) pattern, and the increment of PC risk was observed. The small number of studies included in the meta-analysis suggests that further investigation is necessary to support these findings.

In vitro chemo-preventive activities of hydroxytyrosol: the main phenolic compound present in extra-virgin olive oil.

Abstract: The co-incubation in the culture medium with hydroxytyrosol [3,4-dihydroxyphenyl ethanol (3,4-DHPEA)], the main phenolic compound present in extra-virgin olive oil, and H2O2 reduces the oxidative DNA damage in peripheral blood mononuclear cells (PBMC). In this study we investigate, by the comet assay, the ability of 3,4-DHPEA to inhibit the H2O2 induced DNA damage when pre-incubated with PBMC and then removed before the exposure of cells to H2O2. Low doses of 3,4-DHPEA (10–100 μM) pre-incubated for 30 min with PBMC reduced the DNA damage induced by the treatment with H2O2 200 μM for 5 min at 4 °C. Prolonging the exposure time up to 6 h completely prevented the DNA damage. Furthermore we extensively analysed, by the MTT assay, the anti-proliferative activities of 3,4-DHPEA on breast (MDA and MCF-7), prostate (LNCap and PC3) and colon (SW480 and HCT116) cancer cell lines and correlated these effects with the H2O2 accumulation. The concentration of H2O2 in the culture medium was measured by the ferrous ion oxidation–xylenol orange method. The proliferation of all the cell lines was inhibited but at different levels: the prostate cancer cells were more resistant to the growth inhibition with respect to breast and colon cancer cells. The ability of the different cell lines to remove H2O2 from the culture medium was inversely correlated with their sensitivity to the anti-proliferative effect of 3,4-DHPEA. Therefore, 3,4-DHPEA may act as a chemopreventive agent acting on both initiation and promotion/progression phases of carcinogenesis.

Garlic consumption and colorectal cancer risk in man: a systematic review and meta-analysis.

Abstract: Objective Colorectal cancer shows large incidence variations worldwide that have been attributed to different dietary factors. We conducted a meta-analysis on the relationship between garlic consumption and colorectal cancer risk. Design We systematically reviewed publications obtained by searching ISI Web of Knowledge, MEDLINE and EMBASE literature databases. We extracted the risk estimate of the highest and the lowest reported categories of intake from each study and conducted meta-analysis using a random-effects model. Results The pooled analysis of all fourteen studies, seven cohort and seven case–control, indicated that garlic consumption was not associated with colorectal cancer risk (OR=0·93; 95 % CI 0·82, 1·06, P =0·281; I 2 =83·6 %, P ≤0·001). Separate analyses on the basis of cancer sites and sex also revealed no statistically significant effects on cancer risk. However, when separately analysed on the basis of study type, we found that garlic was associated with an approximately 37 % reduction in colorectal cancer risk in the case–control studies (combined risk estimate=0·63, 95 % CI 0·48, 0·82, P =0·001; I 2 =75·6 %, P ≤0·001). Conclusions Our results suggest that consumption of garlic is not associated with a reduced colorectal cancer risk. Further investigations are necessary to clarify the discrepancy between results obtained from different types of epidemiological studies.

Apple intake and cancer risk: a systematic review and meta-analysis of observational studies.

Abstract: Objective Conflicting results on the association between fruit consumption and cancer risk have been reported. Little is known about the cancer preventive effects of different fruit types. The present meta-analysis investigates whether an association exists between apple intake and cancer risk. Design Relevant observational studies were identified by literature search (PubMed, Web of Science and Embase). A random-effect model was used to estimate the cancer risk in different anatomical sites. Between-study heterogeneity and publication bias were assessed using adequate statistical tests. Results Twenty case–control (three on lung, five on colorectal, five on breast, two on oesophageal, three on oral cavity, two on prostate and one each on pancreas, bladder, larynx, ovary, kidney and brain cancer) and twenty-one cohort (seven on lung, two on colorectal, three on breast and one each on oesophageal, pancreas, bladder, kidney, endometrial, head–neck, urothelial and stomach cancer) studies met the inclusion criteria. Comparing the highest v. lowest level of apple consumption, the reduction of lung cancer risk was statistically highly significant in both case–control (OR=0·75; 95% CI 0·63, 0·88; P=0·001, I 2=0 %) and cohort studies (relative risk=0·89; 95% CI 0·84, 0·94; P<0·001, I 2=53 %). Instead, in the case of colorectal (OR=0·66; 95% CI 0·54, 0·81; P<0·001, I 2=55%), breast (OR=0·79; 95% CI 0·73, 0·87; P<0·001, I 2=1 %) and overall digestive tract (OR=0·50; 95% CI 0·36, 0·69; P<0·001, I 2=90 %) cancers a significant preventive effect of apples was found only in case–control studies while prospective studies indicated no effect. No evidence of publication bias could be detected for colorectal, oral cavity, oesophageal and breast cancer. However, some confounding effects may be present and related to the consumption of other fruit which have not been considered as adjusting factors. Conclusions The present meta-analysis indicates that consumption of apples is associated with a reduced risk of cancer in different anatomical sites.

Oleuropein Prevents Azoxymethane-Induced Colon Crypt Dysplasia and Leukocytes DNA Damage in A/J Mice.

Abstract: Previous studies have shown that the precursor of olive oil secoiridoids, Oleuropein (OL) has several in vitro chemopreventive properties. OL inhibits proliferation and induces apoptosis in breast, thyroid, prostate, and colorectal cancer (CRC) cells. Much less is known about the effects of OL on animal models of carcinogenesis. In this study, we investigated the ability of OL to prevent the azoxymethane (AOM)-induced colon cancer upset and DNA damage in mice. Animals, fed with a basal diet either enriched or not with OL (125 mg/kg), were injected with AOM (10 mg/kg, once a week for 6 weeks) and sacrificed after either 7 weeks for histological analysis of colon crypt dysplasia and evaluation of DNA damage in leukocytes or 17 weeks for counting the macroscopically observable colon tumors. An OL-enriched diet prevented the AOM-induced preneoplastic lesions in different colon segments, reducing the severity of crypt dysplasia and DNA damage in peripheral leukocytes. In addition, OL significantly red...

A Western Dietary Pattern Increases Prostate Cancer Risk: A Systematic Review and Meta-Analysis

Abstract: Dietary patterns were recently applied to examine the relationship between eating habits and prostate cancer (PC) risk. While the associations between PC risk with glycemic index and Mediterranean score have been reviewed, no meta-analysis is currently available on dietary patterns defined by “a posteriori” methods. Search was carried out (PubMed, Web of Science) to identify studies reporting the relationship between dietary patterns and PC risk. Relevant dietary patterns were selected and the risk estimated were calculated by a random-effect model. Multivariable-adjusted odds ratios (ORs) for a 1st-percentile increase in dietary pattern score were combined by a dose response meta-analysis. 12 observational studies were included in the meta-analysis which identified “Healthy pattern” and “Western pattern”. The Healthy pattern was not related to PC risk (OR=0.96; 95% CI: 0.88-1.04) while the Western pattern significantly increased it (OR=1.34; 95% CI: 1.08-1.65). In addition, a “Carbohydrate pattern”, identified in four articles, was positively associated with a higher PC risk (OR=1.64; 95% CI: 1.35-2.00). A significant linear trend between the Western (p=0.011) and the Carbohydrate (p=0.005) pattern and the increment of PC risk was observed. The small numbers of studies included suggest that further investigations are necessary to support these findings.