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The effects of varying dietary carbohydrate and fat content on survival in a murine LNCaP prostate cancer xenograft model.

ABSTRACT: Numerous dietary factors elevate serum levels of insulin and insulin-like growth factor I (IGF-I), both potent prostate cancer mitogens. We tested whether varying dietary carbohydrate and fat, without energy restriction relative to comparison diets, would slow tumor growth and reduce serum insulin, IGF-I, and other molecular mediators of prostate cancer in a xenograft model.Individually caged male severe combined immunodeficient mice (n = 130) were randomly assigned to one of three diets (described as percent total calories): very high-fat/no-carbohydrate ketogenic diet (NCKD: 83% fat, 0% carbohydrate, 17% protein), low-fat/high-carbohydrate diet (LFD: 12% fat, 71% carbohydrate, 17% protein), or high-fat/moderate-carbohydrate diet (MCD: 40% fat, 43% carbohydrate, 17% protein). Mice were fed to maintain similar average body weights among groups. Following a preliminary feeding period, mice were injected with 1 x 10(6) LNCaP cells (day 0) and sacrificed when tumors were >or=1,000 mm(3).Two days before tumor injection, median NCKD body weight was 2.4 g (10%) and 2.1 g (8%) greater than the LFD and MCD groups, respectively (P < 0.0001). Diet was significantly associated with overall survival (log-rank P = 0.004). Relative to MCD, survival was significantly prolonged for the LFD (hazard ratio, 0.49; 95% confidence interval, 0.29-0.79; P = 0.004) and NCKD groups (hazard ratio, 0.59; 95% confidence interval, 0.37-0.93; P = 0.02). Median serum insulin, IGF-I, IGF-I/IGF binding protein-1 ratio, and IGF-I/IGF binding protein-3 ratio were significantly reduced in NCKD relative to MCD mice. Phospho-AKT/total AKT ratio and pathways associated with antiapoptosis, inflammation, insulin resistance, and obesity were also significantly reduced in NCKD relative to MCD tumors.These results support further preclinical exploration of carbohydrate restriction in prostate cancer and possibly warrant pilot or feasibility testing in humans.

SUBMITTER: Mavropoulos JC

PROVIDER: S-EPMC3774034 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature

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The effects of varying dietary carbohydrate and fat content on survival in a murine LNCaP prostate cancer xenograft model.

Mavropoulos John C JC Buschemeyer W Cooper WC Tewari Alok K AK Rokhfeld Dmitriy D Pollak Michael M Zhao Yunhua Y Febbo Phillip G PG Cohen Pinchas P Hwang David D Devi Gayathri G Demark-Wahnefried Wendy W Westman Eric C EC Peterson Bercedis L BL Pizzo Salvatore V SV Freedland Stephen J SJ

Cancer prevention research (Philadelphia, Pa.) 20090526 6

<h4>Purpose</h4>Numerous dietary factors elevate serum levels of insulin and insulin-like growth factor I (IGF-I), both potent prostate cancer mitogens. We tested whether varying dietary carbohydrate and fat, without energy restriction relative to comparison diets, would slow tumor growth and reduce serum insulin, IGF-I, and other molecular mediators of prostate cancer in a xenograft model.<h4>Experimental design</h4>Individually caged male severe combined immunodeficient mice (n = 130) were ran ...[more]

PMID: 19470786

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Project description:PURPOSE: Previous mouse studies using corn oil (ω-6) as the dietary fat source suggest that decreasing dietary fat content can slow prostate cancer (PCa) growth. However, other studies, in which the diet was composed around saturated fat, showed no difference in outcomes between high-fat and low-fat diets. The relative effects of other fats, such as fish oil and olive oil, also remain unexplored. To our knowledge, no trial has yet compared the effect of various fats on prostate cancer progression. Therefore, we sought to systematically study the effect of fish oil, olive oil, corn oil, and saturated fat on prostate cancer progression. METHODS: A total of 96 male SCID mice were injected with LAPC-4 human PCa cells. Two weeks following injection, mice were singly-housed and randomized to either a fish oil, olive oil, corn oil, or saturated fat based diet. Animals were euthanized when tumors reached 1,000 mm3. Serum was collected at sacrifice and assayed for PSA, insulin, IGF-1, IGFBP-3, and PGE-2 levels. Tumors were also assayed for PGE-2, and COX-2 levels, and gene array analysis was performed. RESULTS: Mice weights and tumor volumes were equivalent across groups at randomization. Overall, fish-oil consumption was associated with improved survival, relative to all other dietary groups (Log-rank, all p<0.05). We did not detect any significant difference in serum PSA, insulin, IGF-1, IGFBP-3, and PGE-2 levels. Glucose at the time of sacrifice was statistically different between groups, with the fish-oil fed mice having the highest levels of serum glucose (Kruskal-Wallis, p=0.03). CONCLUSIONS: In this prostate cancer xenograft model, we found that consuming a diet in which fish-oil was the only fat source slowed tumor growth in improved survival, compared to mice consuming diets composed of olive oil, corn oil, or saturated fat sources. These results suggest that type of dietary fat consumed may be as important as amount of dietary fat consumed in the setting of prostate cancer.

Project description:PURPOSE: Previous mouse studies using corn oil (Ï?-6) as the dietary fat source suggest that decreasing dietary fat content can slow prostate cancer (PCa) growth. However, other studies, in which the diet was composed around saturated fat, showed no difference in outcomes between high-fat and low-fat diets. The relative effects of other fats, such as fish oil and olive oil, also remain unexplored. To our knowledge, no trial has yet compared the effect of various fats on prostate cancer progression. Therefore, we sought to systematically study the effect of fish oil, olive oil, corn oil, and saturated fat on prostate cancer progression. METHODS: A total of 96 male SCID mice were injected with LAPC-4 human PCa cells. Two weeks following injection, mice were singly-housed and randomized to either a fish oil, olive oil, corn oil, or saturated fat based diet. Animals were euthanized when tumors reached 1,000 mm3. Serum was collected at sacrifice and assayed for PSA, insulin, IGF-1, IGFBP-3, and PGE-2 levels. Tumors were also assayed for PGE-2, and COX-2 levels, and gene array analysis was performed. RESULTS: Mice weights and tumor volumes were equivalent across groups at randomization. Overall, fish-oil consumption was associated with improved survival, relative to all other dietary groups (Log-rank, all p<0.05). We did not detect any significant difference in serum PSA, insulin, IGF-1, IGFBP-3, and PGE-2 levels. Glucose at the time of sacrifice was statistically different between groups, with the fish-oil fed mice having the highest levels of serum glucose (Kruskal-Wallis, p=0.03). CONCLUSIONS: In this prostate cancer xenograft model, we found that consuming a diet in which fish-oil was the only fat source slowed tumor growth in improved survival, compared to mice consuming diets composed of olive oil, corn oil, or saturated fat sources. These results suggest that type of dietary fat consumed may be as important as amount of dietary fat consumed in the setting of prostate cancer. DESIGN: A total of 96 male SCID mice were injected with LAPC-4 human prostate cancer cells. After 2 weeks of tumor growth, the mice were randomized to one of four diets: corn oil, fish oil, olive oil, and saturated fat source diets. Animals were euthanized when tumor volumes exceeded 1000 mm^3. Sera and tissues from the median 6 surviving animals from each of the four dietary groups were analyzed.

Project description:Fetal programming refers to an intrauterine stimulus or insult that shapes growth, development and health outcomes. Dependent on the quality and quantity, dietary fats can be beneficial or detrimental for the growth of the fetus and can alter insulin signaling by regulating the expression of key factors. The effects of varying dietary fat content on the expression profiles of factors in the neonatal female and male rat heart were investigated and analyzed in control (10% fat), 20F (20% fat), 30F (30% fat) and 40F (40% fat which was a high fat diet used to induce high fat programming) neonatal rats. The whole neonatal heart was immunostained for insulin receptor, glucose transporter 4 (Glut4) and forkhead box protein 1 (FoxO1), followed by image analysis. The expression of 84 genes, commonly associated with the insulin signaling pathway, were then examined in 40F female and 40F male offspring. Maintenance on diets, varying in fat content during fetal life, altered the expression of cardiac factors, with changes induced from 20% fat in female neonates, but from 30% fat in male neonates. Further, CCAAT/enhancer-binding protein alpha (Cebpa) was upregulated in 40F female neonates. There was, however, differential expression of several insulin signaling genes in 40F (high fat programmed) offspring, with some tending to significance but most differences were in fold changes (≥1.5 fold). The increased immunoreactivity for insulin receptor, Glut4 and FoxO1 in 20F female and 30F male neonatal rats may reflect a compensatory response to programming to maintain cardiac physiology. Cebpa was upregulated in female offspring maintained on a high fat diet, with fold increases in other insulin signaling genes viz. Aebp1, Cfd (adipsin), Adra1d, Prkcg, Igfbp, Retn (resistin) and Ucp1. In female offspring maintained on a high fat diet, increased Cebpa gene expression (concomitant with fold increases in other insulin signaling genes) may reflect cardiac stress and an adaptative response to cardiac inflammation, stress and/or injury, after high fat programming. Diet and the sex are determinants of cardiac physiology and pathophysiology, reflecting divergent mechanisms that are sex-specific.

Project description:Purpose: Obesity is a global health issue. To investigate if protein and fat contents of the diets had effects on energy balance via the canonical hunger signaling pathways in the hypothalamus, RNAseq was performed on RNA extracted from the hypothalami of mice exposed to the different diets. A suggested mechanism by which animals may avoid obesity is by burning off excess energy via upregulation of white adipose tissue (WAT) browning. To investigate if protein and fat content of the diet had effects on energy balance via the browning related signaling pathways in the WAT, RNAseq was performed on RNA extracted from the subcutaneous WAT (sWAT) and epididymal WAT (eWAT) of mice exposed to the different diets. Methods: C57BL/6 male mice were used in this work. All mice were fed a standard diet with 10% fat and 20% protein (D12450B, Research Diets Ltd) for 2 weeks as the baseline period. Following 2 weeks of baseline monitoring (at age 12 weeks), all mice were randomly allocated to different groups and switched to the experimental diets for 12 weeks. After 12 weeks all mice were sacrificed and dissected. Methods: In total, mice were fed on 4 diet series, each series consisting of 6 different diets (total = 24 diets). In the first two series (Series 1: D14071601–D14071606 and series 2: D14071607 – D14071612) we fixed the level of fat by energy, and varied the protein content. The protein source was casein. The balance was made up by carbohydrate (roughly equal mix of corn starch and maltodextrose). The source of fat was a mix of cocoa butter, coconut oil, menhaden oil, palm oil and sunflower oil. This mix was designed to match the balance of saturated, mono-unsaturated and polyunsaturated fats (ratio 47.5: 36.8: 15.8) and the n-6: n-3 ratio (14.7: 1) in the typical western diet. The proportions of the different fat constituents and hence fatty acid distributions did not change as the total fat content changed. Sucrose and cellulose were both fixed 5% by energy and weight respectively, and all diets were supplemented with a standard vitamin and mineral mix. In the second two series of diets (series 3: D14071613 – D14071618 and series 4: D14071619 – D14071624) we fixed the level of protein by energy and then allowed the fat content to vary. In these diets the sucrose, cellulose and vitamin and mineral contents were the same as the diets in series 1 and 2. All these diets can be ordered direct from research diets (www.researchdiets.com) using the diet codes provided. Methods: From each diet group, the hypothalami of 8/20 individuals were collected. The left halves of two, and the right halves of another two, were pooled together as one sample, and the same was performed with the other 4 hypothalami, resulting in each diet group having 2 pooled samples of 4 hypothalami (n = 48 samples in total across 24 diets). From each diet group, the sWAT and eWAT of 12/20 individuals were also collected. A small piece from each of six sWAT collections were pooled together as one sample, and the same was performed with the other six eWAT collections. In this way each diet group had one pooled sWAT sample and one pooled eWAT sample (also n = 48 across 24 diets). Methods: The total RNA of the hypothalamus and WAT was isolated using the RNeasy Mini Kit (QIAGEN, 74104) according to manufacturer's protocol. All sequencing was carried out using the Illumina NextSeq 500 sequencer. RNA fragments were sequenced by 75 bp long reads from paired ends (PE 2 x 75 bp, 150 bp per fragment). Quality control checks for raw data FASTQ files were done by using FASTQC (a quality control tool for high throughput sequence data; http://www.bioinformatics.babraham.ac.uk/projects/fastqc/). Paired-end reads were mapped to the Mus musculus genome (GRCm38) using Bowtie 2-2.1.0, TopHat-2.0.10, and Samtools-0.1.19; uniquely mapped reads for each gene were counted against the GTF file of GRCm38 provided by Ensembl (release 83) using HTSeq-0.6.1p1 using the strand = reverse; after read count data were obtained from the TopHat-HTSeq pipeline, counts per million (CPM) value for each gene was calculated by using the R package ‘edgeR’ (version 3.12.0, R version 3.2.2) to normalize the count data by the size of the library of each sample. Genes with the CPM value ≥ 1 in at least one of the 24 diets group were retained (Anders et al., 2013). Generalized Linear Modelling (GLM) was applied by R (version 3.2.2). The GLM model used here was: ~p+f+p:f, which regresses gene expression (CPM) against the protein (p) and fat contents (f) of diets, as well as their interaction (p:f). However, when the effect of the interaction was not significant (p value ≥ 0.05), the interaction term was dropped and a revised model (~p+f) was utilized. Results: With TopHat-HTSeq pipeline, reads of each sample were mapped to 46,078 genes. In hypothalamus there were 15,371 genes with the counts per million (CPM) value ≥ 1 in at least one of the 24 diets group; in white adipose tissue there were 18,202 genes with the CPM value ≥ 1 in at least one of the 24 diets group. No major changes in hypothalamic gene expression levels were found in relation to different dietary protein levels at fixed fat contents, however hypothalamic gene expression showed increase in expression of genes in reward pathways in relation to dietary fat, while Agrp and Npy were both downregulated in relation to dietary fat levels. WAT gene expression showed decrease in expression of general thermogenic related genes and WAT browning related genes in relation to both dietary protein and dietary fat, while Tgfb1, Pdk4 and Fgf1 were all upregulated in relation to dietary fat levels. Conclusions: Significant positive associations were evident between the fat levels of the diet and the main hedonic signaling systems linked to food intake. Significant negative associations were found between both protein and fat levels of the diet and WAT browning or general thermogenic signalings linked to energy expenditure.

Dataset Information

The effects of varying dietary carbohydrate and fat content on survival in a murine LNCaP prostate cancer xenograft model.

Publications

The effects of varying dietary carbohydrate and fat content on survival in a murine LNCaP prostate cancer xenograft model.

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