Fish Oil Enhances T Cell Function and Tumor Infiltration and Is Correlated With a Cancer Prevention Effect in HER-2/neu But Not PyMT Transgenic Mice

Effects of Polyunsaturated Fatty Acids on Colorectal Cancer Patients: A Meta-Analysis of Randomized Controlled Trials

This study aimed to investigate the effects of polyunsaturated fatty acids (PUFAs) on patients with colorectal cancer (CRC). Electronic databases such as PubMed and Web of Science were searched. Studies on the application of PUFAs in patients with CRC, published up to January 2022, were conducted. Twelve studies involving 702 CRC patients were included. For patients undergoing surgery, subgroup analyses indicated that preoperative supplementation with PUFAs improved total postoperative infectious complications (RR: 0.37, p = 0.02). Furthermore, the supplementation of PUFAs in preoperative (WMD: -2.27, p < 0.001) and postoperative (WMD: -2.66, p = 0.01) groups was effective in shortening the postoperative hospital stay for patients with CRC. Tumor necrosis factor-α (TNF-α) (SMD: -0.56, p = 0.007) and interleukin-6 (IL-6) (SMD: -0.54, p = 0.004) levels were lower in all CRC patients receiving PUFAs intervention than in the control group. Moreover, supplementation with PUFAs in chemotherapy patients significantly increased albumin (WMD: 0.48, p = 0.03) and decreased C-reactive protein (CRP) (WMD: -6.12, p = 0.02) compared to the control group. This study demonstrated that PUFAs intervention could diminish the total postoperative infection complications of CRC patients, shorten the postoperative hospital stay, and reduce inflammation.

Associations between omega-3 polyunsaturated fatty acids supplementation and surgical prognosis in patients with gastrointestinal cancer: A systematic review and meta-analysis

Background

Surgical resection remains the primary treatment for gastrointestinal (GI) cancer, omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been reported to improve the prognosis of patients undergoing gastrointestinal tumor surgery. This meta-analysis aims to explore the efficacy of n-3 PUFAs on GI cancer patients undergoing surgery.

Methods

A systematic search of PubMed, Cochrane Library databases, EMBASE (until December 2021) was conducted. PRISMA checklist was followed. The data were analyzed by RevMan v5.3.0.

Results

A total of ten RCTs articles including 663 patients were studied. The analysis demonstrated that the n-3 PUFAs group significantly reduced levels of interleukin-6 (IL-6) (P = 0.001), C-reactive protein (CRP) (P < 0.00001), tumor necrosis factor-ɑ (TNF-α) (P = 0.0003) compared with the control group. and higher levels of CD4⁺T cells (P = 0.03), CD8⁺T cells (P = 0.02) and CD4⁺/CD8⁺ratio (P = 0.03) compared with the control group. but there was no significant difference in infection complications rate (P = 0.50) and the level of prealbumin (P = 0.80), albumin (P = 0.21), retinol-binding protein(P = 0.80) between the two groups. In addition, the n-3 PUFAs group significantly reduced the length of hospital stay (P = 0.007).

Conclusion

Our meta-analysis shows that n-3 PUFAs can effectively improve the immune function of patients undergoing gastrointestinal cancer surgery, reduce inflammatory response and reduce the length of hospital stay, But it has no significant impact on the incidence of infectious-related complications and the level of nutrient protein.

Maternal fish oil consumption has a negative impact on mammary gland tumorigenesis in C3(1) Tag mice offspring

PURPOSE

Omega-3 fatty acids have been shown to reduce the incidence and slow the growth of mammary gland cancer in rodent models. Since exposure to dietary components during the critical developmental times of gestation and lactation may alter risk for mammary gland cancer in females, we tested whether exposure to increased levels of long-chain omega-3 fatty acids from fish oils would be preventive or promotional to mammary gland cancer in the offspring.

METHODS

Normal SV129 female mice were fed AIN 76 diets containing either 10% corn oil (control, 50% omega 6, n-6) or 5% of an omega-3 (n-3) fatty acid concentrate (fish oil 60% n-3) + 5% canola oil (10% n-3 + 20% n-6). Females were then mated with C(3)1 TAg transgenic mice. At weaning (3 weeks), pups were randomized to either the corn (C) or fish oil (F) diet, 15-17 mice per group. Four experimental groups were generated: FF, FC, CF and CC. Tumor incidence and multiplicity were assessed at the following time points 120, 130 and 140 days of age. A panel of genes encoding signal transduction proteins were analyzed in mammary glands at 130 days.

RESULTS

Mice never exposed to fish oil (CC group) had a significantly higher incidence and multiplicity of mammary gland tumors than mice exposed to fish oil throughout life (FF group). Mice exposed to fish oil during a portion of life (CF or FC) had intermediate tumor incidences and multiplicities. Results also indicate that maternal consumption of fish oil increased the expression of genes associated with immune system activation (Ccl20, Cd5, Il2, Lef1, Lta).

CONCLUSIONS

Adequate omega-3 fatty acids in the maternal diet may reduce the risk for mammary gland cancer in the offspring. If humans make dietary change by consuming more omega-3 fat instead of corn oil with 0% omega 3 fat, breast cancer may be reduced in the next generation.

Lipid Metabolism in Tumor-Infiltrating T Cells

T cells recognize "foreign" antigens and induce durable humoral and cellular immune responses, which are indispensable for defending pathogens, as well as maintaining the integrity and homeostasis of tissues and organs. T cells are the major immune cell population in the tumor microenvironment which play a critical role in the antitumor immune response and cancer immune surveillance. Defective immune response of tumor-infiltrating T cells is the main cause of cancer immune evasion. The antitumor response of T cells is affected by multiple factors in the tumor microenvironment, including immunosuppressive cells, immune inhibitory cytokines, tumor-derived suppressive signals like PD-L1, immnuogenicity of tumor cells, as well as metabolic factors like hypoxia and nutrient deprivation. Abundant studies in past decades have proved the metabolic regulations of the immune response of T cells and the tumor-infiltrating T cells. In this chapter, we will discuss the regulations of the antitumor response of tumor-infiltrating T cells by lipid metabolism, which is one of the main components of metabolic regulation.

Targeting the tumor immune microenvironment with "nutraceuticals": From bench to clinical trials

The occurrence of immune effector cells in the tissue microenvironment during neoplastic progression is critical in determining tumor growth outcomes. On the other hand, tumors may also avoid immune system-mediated elimination by recruiting immunosuppressive leukocytes and soluble factors, which coordinate a tumor microenvironment that counteracts the efficiency of the antitumor immune response. Checkpoint inhibitor therapy results have indicated a way forward via activation of the immune system against cancer. Widespread evidence has shown that different compounds in foods, when administered as purified substances, can act as immunomodulators in humans and animals. Although there is no universally accepted definition of nutraceuticals, the term identifies a wide category of natural compounds that may impact health and disease statuses and includes purified substances from natural sources, plant extracts, dietary supplements, vitamins, phytonutrients, and various products with combinations of functional ingredients. In this review, we summarize the current knowledge on the immunomodulatory effects of nutraceuticals with a special focus on the cancer microenvironment, highlighting the conceptual benefits or drawbacks and subtle cell-specific effects of nutraceuticals for envisioning future therapies employing nutraceuticals as chemoadjuvants.

Increased Adiposity Enhances the Accumulation of MDSCs in the Tumor Microenvironment and Adipose Tissue of Pancreatic Tumor-Bearing Mice and in Immune Organs of Tumor-Free Hosts

Obesity is associated with increased risk and reduced survival for many types of cancer. Increasing adiposity may affect the balance between immunosuppressive and antitumor mechanisms critical for dictating cancer progression or remission. The goal of the current study was to determine if increased adiposity altered tumor growth, survival, and myeloid-derived suppressor cell (MDSC) accumulation in a subcutaneous murine model of pancreatic cancer. C57BL/6 mice were placed on a 30% kcal calorie-restricted diet, 10% kcal from fat diet fed ad libitum, or 60% kcal from fat diet fed ad libitum for 16 weeks to generate lean, overweight, and obese mice, respectively; followed by subcutaneous injection with 1 × 10⁶ Panc.02 cells. We observed a significant linear relationship between increased adiposity and increased tumor growth and mortality; increased accumulation of Gr-1⁺CD11b⁺ MDSCs; and reduced CD8 T cell:MDSC ratio in multiple tissues, including tumor. Increased adiposity also increased the accumulation of MDSCs in the spleen and lymph node of tumor-free mice. These data suggest adiposity induces MDSC accumulation, which may contribute to an immunosuppressive environment promoting tumor growth. Overall, our findings provide a rationale to prevent or reverse increased body weight as a strategy to reduce the accumulation of immunosuppressive cell types.

Physical Activity Plus Energy Restriction Prevents 4T1.2 Mammary Tumor Progression, MDSC Accumulation, and an Immunosuppressive Tumor Microenvironment

Physical activity and the prevention of weight gain decrease breast cancer incidence and improve survival. Unraveling the biological mechanisms underlying these cancer prevention effects is difficult because activity and dietary restriction are often linked. The goal of this study was to determine whether physical activity (PA), preventing weight gain via energy restriction (ER), or the combination was most effective in delaying tumor growth, reducing metastatic progression, and improving survival in the 4T1.2 mammary tumor model. Furthermore, we determined whether any of these interventions prevented the expansion of protumor immunosuppressive cells and altered the tumor microenvironment (TME). Female BALB/c mice (n = 7-20/group) were randomized to sedentary (SED) or PA wheel cages and fed ad libitum (AL) or 90% of control food intake (ER). After 8 weeks on the interventions, mice were inoculated with 5 × 10⁴ 4T1.2^luc cells into the 4th mammary fat pad and continued on their respective intervention. PA+ER significantly delayed primary tumor growth (final tumor volume, 0.193 ± 0.042 vs. 0.369 ± 0.049 cm³, P < 0.001), reduced metastatic burden in the lungs (0.72 ± 0.36 vs. 16.27 ± 6.98, P = 0.054) and increased survival (median survival, 68 vs 40 days, P = 0.043) compared with SED+AL mice. PA+ER also reduced the expression level of metastatic and immunosuppressive genes and resulted in favorable changes in immune cell infiltrates in the tumor. These data suggest that both PA and ER are needed to reduce tumor growth, delay metastatic progression, and improve survival, and that this protection is associated with changes in immune-mediated mechanisms.

Effects of omega-3 fatty acids on patients undergoing surgery for gastrointestinal malignancy: a systematic review and meta-analysis

Background

Surgical resection remains the primary treatment for gastrointestinal (GI) malignancy including early-stage cancer. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been reported to have beneficial clinical and immune-modulating effects in the prognosis of GI cancer patients undergoing surgery.

Methods

We searched PubMed, Embase, EBSCO-Medline, Cochrane Central Register of Controlled Trials (CENTRAL), CNKI and Wanfang to identify primary research reporting the effects of n-3 PUFAs compared with isocaloric nutrition on GI cancer patients who underwent surgery up to the end of June 30, 2016. Two authors independently reviewed and selected eligible randomized controlled trials (RCTs).

Results

A total of 9 RCTs (623 participants) were included. The n-3 PUFAs regime resulted in lower levels of C-reactive protein (CRP) (P < 0.05), interleukin-6 (IL-6) (P < 0.01), and higher levels of albumin (ALB), CD3⁺ T cells, CD4⁺ T cells and CD4⁺/CD8⁺ ratio (P < 0.05) compared with the isocaloric nutrition regime. However, there was no significant difference in the level of tumor necrosis factor-α (TNF-α) between the n-3 PUFAs regime and the isocaloric nutrition regime (P = 0.17). And the level of CD8 ⁺ T cells decreased compared with the isocaloric nutrition regime (P < 0.0001).

Conclusions

Our meta-analysis revealed that n-3 PUFAs are effective in improving the nutritional status and immune function of GI cancer patients undergoing surgery as they effectively enhance immunity and attenuate the inflammatory response.