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Normalizing body weight with a dietary strategy mitigates obesity-accelerated pancreatic carcinogenesis in mice

ABSTRACT: Although obesity is a modifiable risk factor for pancreatic cancer, the role of dietary changes that lead to weight loss in pancreatic carcinogenesis remains unknown. Thus, we determined the effects of weight normalization via dietary switch on pancreatic carcinogenesis and the associated mechanisms. Five-week-old male and female LSL-KrasG12D/+; p48Cre/+ (KC) mice (8-12/diet group/sex) were fed a high-fat, diet-induced obesity diet (DIO; 60 kCal% energy from fat) or a low-fat, control diet (CD; 11 kCal% energy from fat) for 21 weeks. A subset of mice was fed the DIO for 8 weeks, then switched to a CD for 13 additional weeks (DIO→CD). Cancer incidence was evaluated by histology. Lipidomics and RNAseq followed by bioinformatic analysis were conducted to identify possible mechanisms. The gut microbiome was characterized using 16s rRNA amplicon sequencing. After 21 weeks, DIO-fed mice had significantly higher body weight, fat mass, and pancreatic acinar-to-ductal metaplasia compared to the other 2 groups. While none of the 21 mice fed a CD developed cancer, 2 out of 21 DIO-fed mice did. Switching from a DIO to a CD normalized body weight and composition, reduced acinar-to-ductal metaplasia and prevented cancer incidence with no mice developing cancer. Mechanistically, the DIO affected the expression of genes regulating cellular metabolism, immune function, and cell-signaling, while CD and DIO→CD had similar global gene expression. Moreover, DIO increased epoxy metabolites of linoleic acid, which were mitigated by the dietary switch. Finally, compared to a CD, DIO altered the gut microbiome and switching from a DIO to a CD restored the gut microbiome profile to one close to the mice fed a CD. Body weight normalization mitigates obesity-accelerated pancreatic carcinogenesis, in part, by affecting inflammatory and cell signaling pathways, reducing epoxy metabolites, and modulating the gut microbiome.

ORGANISM(S): Mus musculus

PROVIDER: GSE293790 | GEO | 2025/08/30

REPOSITORIES: GEO

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Project description:Pancreatic cancer is the 3rd most prevalent cause of cancer related deaths in United states alone, with over 55000 patients being diagnosed in 2019 alone and nearly as many succumbing to it. Late detection, lack of effective therapy and poor understanding of pancreatic cancer systemically contributes to its poor survival statistics. Obesity and high caloric intake linked co-morbidities like type 2 diabetes (T2D) have been attributed as being risk factors for a number of cancers including pancreatic cancer. Studies on gut microbiome has shown that lifestyle factors as well as diet has a huge effect on the microbial flora of the gut. Further, modulation of gut microbiome has been seen to contribute to effects of intensive insulin therapy in mice on high fat diet. In another study, abnormal gut microbiota was reported to contribute to development of diabetes in Db/Db mice. Recent studies indicate that microbiome and microbial dysbiosis plays a role in not only the onset of disease but also in its outcome. In colorectal cancer, Fusobacterium has been reported to promote therapy resistance. Certain intra-tumoral bacteria have also been shown to elicit chemo-resistance by metabolizing anti-cancerous agents. In pancreatic cancer, studies on altered gut microbiome have been relatively recent. Microbial dysbiosis has been observed to be associated with pancreatic tumor progression. Modulation of microbiome has been shown to affect response to anti-PD1 therapy in this disease as well. However, most of the studies in pancreatic cancer and microbiome have remained focused om immune modulation. In the current study, we observed that in a T2D mouse model, the microbiome changed significantly as the hyperglycemia developed in these animals. Our results further showed that, tumors implanted in the T2D mice responded poorly to Gemcitabine/Paclitaxel (Gem/Pac) standard of care compared to those in the control group. A metabolomic reconstruction of the WGS of the gut microbiota further revealed that an enrichment of bacterial population involved in drug metabolism in the T2D group.

Project description:To profile the expression of circulating miRNAs in a mouse model of diet-induced obesity (DIO) with subsequent weight-reduction with low-fat diet (LFD), eighteen C57BL/6 male mice were grouped into three subgroups as: (1) Control: the mice fed with the standard AIN-76A (fat: 11.5 kcal%) diet for 12 wks; (2) DIO: the mice fed with 58 kcal% high-fat diet for 12 wks; (3) DIO+LFD: the mice fed with high-fat diet for 8 wks to induce obesity, then changed to 10.5 kcal% low-fat diet for subsequent 4 wks. C57BL/6 mice were purchased from BioLasco (Taipei, Taiwan). All housing conditions were maintained, and surgical procedures, including analgesia, were performed in an Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC)-accredited SPF facility according to national and institutional guidelines. In this experiment, eighteen C57BL/6 wild type male mice were randomly grouped into three subgroups (n=6 in each group): (1) Control: the control mice were fed ad libitum a standard AIN-76A (fat: 11.5 kcal%) diet for 12 wks; (2) DIO: the mice were fed ad libitum a 58 kcal% HFD (D12331; Research Diets Inc., New Brunswick, NJ) for 12 wks to induce obesity; (3) DIO+LFD: the mice fed ad libitum a 58 kcal% HFD (D12331) for 8 wks to induce obesity, then continued the feeding of 10.5 kcal% LFD (D 12329; Research Diets Inc.) for additional 4 wks. Weight measurements were performed on a weekly basis to for these three groups of mice. Evaluation of blood glucose levels was performed at the beginning and in the end of the experiment to confirm that the HFD-fed mice developed an obese and insulin resistant phenotype. After the end of experiment at 12w, all mice were killed. The abdominal WAT of each mice was removed and weighted. Paraffin-embedded abdominal WAT was sectioned at 5 M-NM-<m and stained with hematoxylin and eosin to measure mean adipocyte area. A volume of 1 mL of whole blood was collected into a plain tube and allowed to clot for 1 hour. The sera samples were aliquoted after centrifugation at 3,000 M-CM-^W g for 10 minutes and stored at M-bM-^HM-^R80M-BM-0C until further analysis.

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Normalizing body weight with a dietary strategy mitigates obesity-accelerated pancreatic carcinogenesis in mice

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