Obesity Programs Macrophages to Support Cancer Progression

Leptin Enhances M1 Macrophage Polarization and Impairs Tendon-Bone Healing in Rotator Cuff Repair: A Rat Model

BACKGROUND

Rotator cuff tears are common, affecting more than 60% of individuals older than 80 years, and they have been implicated in 70% of patients with shoulder pain. M1 polarization-related inflammation has been reported to be associated with poor healing outcomes of rotator cuff injury, and leptin, an adipokine, has been reported to be a potential activator of inflammation. However, whether leptin affects rotator cuff repair remains unknown.

QUESTIONS/PURPOSES

Using in vitro cell experiments and an in vivo rat rotator cuff tear model, we therefore asked: (1) Does leptin promote the M1 polarization of macrophages in vitro and in vivo? (2) Does leptin impair biomechanical strength, the histologic structure of the tendon-bone interface, bone mineral density (BMD), or gait in the rotator cuff tear scenario? (3) Does leptin promote M1 polarization by upregulating the tumor necrosis factor (TNF) pathway?

METHODS

The impact of leptin on M1 macrophage polarization in vitro was determined by reverse transcription-polymerase chain reaction (RT-PCR), the Western blot test, and immunofluorescence staining. The effect of leptin on tendon-bone healing was assessed in an in vivo rat rotator cuff tear model by comparing a leptin group with a suture group in terms of gait, biomechanical tensile strength, the histologic structure of the tendon-bone interface, and BMD. In the in vivo experiments, 8-week-old male Sprague Dawley rats were used, adapting a previously developed rat rotator cuff tear model. The supraspinatus tendon was resected from the greater tuberosity bilaterally, and then the tendon was secured to its anatomical footprint using the transosseous single-row technique. In total, 30 rats were randomized into two groups (suture, leptin) by drawing lots (15 rats in each group). They were assessed at 2, 4, and 8 weeks after the surgery. In the suture group, 100 µL of normal saline was injected into the subacromial space after the deltoid muscle was restitched to the original position. In the leptin group, 100 µL of leptin solution (200 ng/mL) was injected into the subacromial space after the deltoid muscle was restitched to the original position. Biomechanical properties including maximal failure load, stiffness, and tensile failure stress were determined to assess the biomechanical strength at 4 and 8 weeks after the surgery. Histologic staining was conducted to compare the structure of the tendon-bone interface between treatment groups. Micro-MRI and micro-CT assessments were conducted to compare the overall healing outcome and BMD between treatment groups. Gait analysis was conducted to compare the stride length and strength between treatment groups. M1 macrophage polarization in vivo at the tendon-bone interface was assessed by immunofluorescence staining. Finally, to explore the underlying mechanism of the effects of leptin, Necrostatin-1 (Nec-1) was used to block the TNF signaling pathway in the in vitro macrophage study, and RT-PCR and Western blot were used to explore the underlying mechanism.

RESULTS

Leptin enhanced LPS-induced M1 polarization of macrophages in vitro, showing increased gene expression of CD86, Nos2, and TNF-α as well as increased protein expression of CD86, TNF-α, interleukin-6 (IL-6), and inducible NO synthase (iNOS). The in vivo polarization showed that the M1 polarization of macrophages at the tendon-bone interface was promoted. At 2 weeks postoperatively, there were more M1 cells in the leptin group (53 ± 5 versus 77 ± 8, mean difference 24 [95% confidence interval (CI) 11 to 37]; p = 0.002), although the proportion of M1 cells (ratio of the number of M1 cells to the total number of macrophages) was not higher (18.6% ± 2.9% versus 21.5% ± 1.7%, mean difference 2.9% [95% CI -2.8% to 8.7%]; p = 0.36). At 4 weeks postoperatively, the leptin group exhibited more M1 cells (31 ± 4 versus 50 ± 6, mean difference 19 [95% CI 6 to 32]; p = 0.008) and at a higher proportion (16.4% ± 2.6% versus 23.0% ± 3.0%, mean difference 6.6% [95% CI 0.8% to 12.4%]; p = 0.03). The in vivo experiments showed that leptin impaired tendon-bone healing. At 4 weeks postoperatively, the biomechanical properties of both groups were not different in terms of maximal failure load (12.7 ± 1.6 N versus 12.4 ± 1.8 N, mean difference -0.3 N [95% CI -2.6 to 1.8]; p = 0.91), stiffness (5.1 ± 0.7 N/mm versus 4.6 ± 0.8 N/mm, mean difference -0.5 N/mm [95% CI -1.3 to 0.5]; p = 0.44), and tensile failure stress (2.0 ± 0.3 N/mm 2 versus 2.0 ± 0.3 N/mm 2 , mean difference 0.0 N/mm 2 [95% CI -0.4 to 0.4]; p = 0.99). At 8 weeks postoperatively, the leptin group showed worse maximal failure load (17.6 ± 1.4 N versus 14.1 ± 1.4 N, mean difference -3.5 N [95% CI -5.7 to -1.3]; p = 0.002), stiffness (7.0 ± 0.6 N/mm versus 5.2 ± 0.6 N/mm, mean difference -1.8 N/mm [95% CI -2.7 to -0.9]; p < 0.001), and tensile failure stress (3.4 ± 0.3 N/mm 2 versus 2.8 ± 0.4 N/mm 2 , mean difference -0.6 N/mm 2 [95% CI -1.0 to -0.2]; p = 0.007). Results of histologic staining, image assessments, and gait analysis also demonstrated that leptin impaired the healing process. In vitro experiments showed that leptin upregulated the gene expression of molecules in the TNF pathway, including CCL2 and receptor-interacting protein kinase 1 (RIPK1), and M1 markers, such as TNF-α, CD86, and Nos2; the addition of Nec-1 neutralized the effect of leptin on macrophage polarization, reducing the expression of M1 markers, including TNF-α, CD86, and Nos2, and blocking the TNF signaling pathway, including CCL2 and RIPK. The protein expression exhibited similar trends.

CONCLUSION

Based on the results of this study, leptin appears to impair tendon-bone healing in a rat model of rotator cuff tear, promote M1 macrophage polarization at the tendon-bone interface, and upregulate the TNF signaling pathway in macrophages to promote M1 polarization.

CLINICAL RELEVANCE

Obesity and fatty infiltration of the rotator cuff muscle are associated with poor healing of rotator cuff tears. In this study, the effect of leptin, an adipose factor, on tendon-bone healing and the underlying mechanism were explored. Future studies might focus on developing novel approaches to improve the tendon-bone healing in patients with obesity by targeting leptin or the TNF signaling pathway with the aid of biomaterials.

Adipokines: masterminds of metabolic inflammation

Adipose tissue is an immunologically active organ that controls host physiology, partly through the release of mediators termed adipokines. In obesity, adipocytes and infiltrating leukocytes produce adipokines, which include the hormones adiponectin and leptin and cytokines such as tumour necrosis factor and IL-1β. These adipokines orchestrate immune responses that are collectively referred to as metabolic inflammation. Consequently, metabolic inflammation characterizes metabolic disorders and promotes distinct disease aspects, such as insulin resistance, metabolic dysfunction-associated liver disease and cardiovascular complications. In this unifying concept, adipokines participate in the immunological cross-talk that occurs between metabolically active organs in metabolic diseases, highlighting the fundamental role of adipokines in obesity and their potential for therapeutic intervention. Here, we summarize how adipokines shape metabolic inflammation in mice and humans, focusing on their contribution to metabolic disorders in the setting of obesity and discussing their value as therapeutic targets.

THE GROWING EVIDENCE OF THE RELATIONSHIP BETWEEN OBESITY AND CANCER AND THE ROLE OF BARIATRIC SURGERY

Obesity is recognized as a significant risk factor for various types of cancer. Although the incidence of some types of cancer across various primary sites is decreasing due to specific prevention measures (screening programs, smoking cessation), the incidence of neoplasms in the young population shows a significant increase associated with obesity. There is sufficient evidence to say that bariatric surgery has been shown to significantly lower the risk of developing obesity-associated cancers, which are linked to metabolic dysregulation, chronic low-grade systemic inflammation, and hormonal alterations such as elevated levels of insulin and sex hormones.

Obesity-derived macrophages upregulate TNF-α to induce apoptosis in glial cell via the NF-κB/PHLPP1 axis

Macrophages in obese adipose tissue have been shown to damage nerve fibers, however, the mechanism underlying how macrophages cause glial cell damage remains unknown. This study aimed to characterize the mechanism by which macrophages induce apoptosis in glial cell during obesity formation in mice by single-nucleus RNA sequencing (snRNA-seq). Cells obtained from paraepididymal adipose tissue in obese mice underwent snRNA-seq. Eighteen different clusters were identified, and 12 cell types were annotated, including glial cells, macrophages, and fibroblasts. There was a negative correlation between the number of glial cells and macrophages in mouse adipose tissue during the formation of obesity. The pro-apoptotic factor PHLPP1 was identified in GO Terms. The interaction between adipose tissue glial cells and macrophages was revealed via in-depth analysis, and the cell-cell communication mechanism between the TNF-α and NF-KB/PHLPP1 axes was perfected. Apoptosis of glial cell by upregulation of TNF-α via obesity-derived macrophages and activation of the NF-κB/PHLPP1 axis. We further revealed how macrophages induce apoptosis in glial cells during obesity formation, as well as different changes in the two cell populations. This study provides valuable resources and foundations for understanding the mechanistic effects of macrophages and glial cells during obesity formation, as well as diseases and potential interventions.

Triglyceride-glucose index predicts postoperative overall survival in hepatocellular carcinoma: a retrospective cohort study

BACKGROUND

Insulin resistance is important in hepatocellular carcinoma (HCC) carcinogenesis and progression. The triglyceride-glucose (TyG) index, triglyceride to high-density lipoprotein cholesterol (TG/HDL-c) ratio or TyG-body mass index (TyG-BMI) are three non-invasive parameters for insulin resistance. However, their prognostic role in HCC patients undergoing hepatectomy remains unclear.

MATERIALS AND METHODS

HCC patients who underwent hepatectomy at the Meizhou People's Hospital from May 2011 to February 2023 were retrospectively explored. Patients were classified into high and low groups based on different TyG, TG/HDL-c, and TyG-BMI indices. The prognostic role of TyG, TG/HDL-c, and TyG-BMI was evaluated using Kaplan-Meier analysis and Cox regression models. A nomogram incorporating significant prognostic factors was constructed and validated.

RESULTS

A lower TyG, lower TG/HDL-c, and lower TyG-BMI were linked to worse overall survival (OS) in HCC patients. Multivariate analysis indicated the TyG index, but not the TG/HDL-c and TyG-BMI index, could independently predict HCC OS. The nomogram incorporating the TNM stage and TyG index demonstrated good calibration, discriminative ability, and clinical benefit for predicting OS in HCC patients.

CONCLUSIONS

The TyG index could independently predict HCC OS after hepatectomy in this cohort. The nomogram incorporating the TyG index may aid in the prognosis management of HCC.

Glucagon-like peptide-1 (GLP-1) receptor agonists for weight management: A review for the gynecologic oncologist

The use of glucagon-like peptide-1 receptor agonists (GLP-1RA) has experienced rapid growth amidst the obesity epidemic in the United States. While originally developed for glucose control in Type 2 Diabetes Mellitus, the scope of these agents now extends to encompass weight loss and cardiovascular risk reduction. GLP-1RAs have the potential to induce significant weight loss, in combination with lifestyle modifications, among adults who are overweight or obese. Furthermore, these agents demonstrate efficacy in ameliorating hyperglycemia, enhancing insulin sensitivity, regulating blood pressure, improving cardiometabolic parameters, mitigating kidney dysfunction, and potentially reducing the risk of several obesity-related cancers. Drug-related toxicity is primarily gastrointestinal and active management can prevent drug discontinuation. Obesity is associated both with an increased incidence of malignancy but also with decreased survival. More research is needed to evaluate the potential use of GLP-1RA to modify the endocrine function of adipocytes, regulate the chronic inflammatory state associated with obesity, and prospective applications in oncology. These agents can impact patients with gynecologic malignancies both through their direct mechanism of action as well as potential drug toxicity.

The acid-sensing receptor GPR65 on tumor macrophages drives tumor growth in obesity

Multiple cancers, including colorectal cancer (CRC), are more frequent and often more aggressive in individuals with obesity. Here, we showed that macrophages accumulated within tumors of patients with obesity and CRC and in obese CRC mice and that they promoted accelerated tumor growth. These changes were initiated by oleic acid accumulation and subsequent tumor cell-derived acid production and were driven by macrophage signaling through the acid-sensing receptor GPR65. We found a similar role for GPR65 in hepatocellular carcinoma (HCC) in obese mice. Tumors in patients with obesity and CRC or HCC also exhibited increased GPR65 expression, suggesting that the mechanism revealed here may contribute to tumor growth in a range of obesity-associated cancers and represent a potential therapeutic target.

ROS-triggered and macrophage-targeted micelles modulate mitochondria function and polarization in obesity

Inflammation involving adipose macrophages is an important inducer of obesity. Regulating macrophages polarization and improving the inflammatory microenvironment of adipose tissue is a new strategy for the treatment of obesity. An amphiphilic chondroitin sulfate phenylborate derivative (CS-PBE) was obtained by modifying the main chain of chondroitin sulfate with the hydrophobic small molecule phenylborate. Using CS-PBE self-assembly, macrophage targeting, reactive oxygen species (ROS) release and celastrol (CLT) encapsulation were achieved. The cytotoxicity, cellular uptake, internalization pathways and transmembrane transport efficiency of CS-PBE micelles were studied in Caco-2 and RAW264.7 cells. Hemolysis and organotoxicity tests were performed to assess the safety of the platform, while its therapeutic efficacy was investigated in high-fat diet-induced obese mice. Multifunctional micelles with macrophage targeting and ROS clearance capabilities were developed to improve the efficacy of CLT in treating obesity.In vitrostudies indicated that CS-PBE micelles had better ability to target M1 macrophages, better protective effects on mitochondrial function, better ability to reduce the number of LPS-stimulated M1 macrophages, better ability to reduce the number of M2 macrophages, and better ability to scavenge ROS in inflammatory macrophages.In vivostudies have shown that CS-PBE micelles improve inflammation and significantly reduce toxicity of CLT in the treatment of obesity. In summary, CS-PBE micelles could significantly improve the ability to target inflammatory macrophages and scavenge ROS in adipose tissue to alleviate inflammation, suggesting that CS-PBE micelles are a highly promising approach for the treatment of obesity.

Fat Phagocytosis Promotes Anti-Inflammatory Responses of Macrophages in a Mouse Model of Osteonecrosis

Osteonecrosis (ON) of the femoral head (ONFH) is a devastating bone disease affecting over 20 million people worldwide. ONFH is caused by a disruption of the blood supply, leading to necrotic cell death and increased inflammation. Macrophages are the key cells mediating the inflammatory responses in ON. It is unclear what the dynamic phenotypes of macrophages are and what mechanisms may affect macrophage polarization and, therefore, the healing process. In our preliminary study, we found that there is an invasion of macrophages into the repair tissue during ON healing. Interestingly, in both ONFH patients and a mouse ON model, fat was co-labeled within macrophages using immunofluorescence staining, indicating the phagocytosis of fat by macrophages. To study the effects of fat phagocytosis on the macrophage phenotype, we set up an in vitro macrophage and fat co-culture system. We found that fat phagocytosis significantly decreased M1 marker expression, such as IL1β and iNOS, in macrophages, whereas the expression of the M2 marker Arg1 was significantly increased with fat phagocytosis. To investigate whether the polarization change is indeed mediated by phagocytosis, we treated the cells with Latrunculin A (LA, which inhibits actin polymerization and phagocytosis). LA supplementation significantly reversed the polarization marker gene changes induced by fat phagocytosis. To provide an unbiased transcriptional gene analysis, we submitted the RNA for bulk RNA sequencing. Differential gene expression (DGE) analysis revealed that the top upregulated genes were related to anti-inflammatory responses, while proinflammatory genes were significantly downregulated. Additionally, using pathway enrichment and network analyses (Metascape), we confirmed that gene-enriched categories related to proinflammatory responses were significantly downregulated in macrophages with fat phagocytosis. Finally, we validated the similar macrophage phenotype changes in vivo. To summarize, we discovered that fat phagocytosis occurs in both ONFH patients and an ON mouse model, which inhibits proinflammatory responses with increased anabolic gene expression in macrophages. This fat-phagocytosis-induced macrophage phenotype is consistent with the in vivo changes shown in the ON mouse model. Our study reveals a novel phagocytosis-mediated macrophage polarization mechanism in ON, which fills in our knowledge gaps of macrophage functions and provides new concepts in macrophage immunomodulation as a promising treatment for ON.

A preliminary mechanistic exploration of the effect of leptin on the docetaxel sensitivity of MDA‑MB‑231 triple‑negative breast cancer cells

Breast cancer is a common tumor encountered in women, and triple-negative breast cancer (TNBC) has an extremely poor prognosis. The effect of leptin on the docetaxel sensitivity of MDA-MB-231 TNBC cells has not been investigated. The present study aimed to clarify the effect of leptin and M2 tumor-associated macrophages (TAMs) on the chemosensitivity of TNBC cell lines and its possible mechanisms. In the present study, the apoptosis of the MDA-MB-231 cell line was detected at 0, 24, 48 and 72 h using a Cell Counting Kit-8 assay to determine the appropriate concentration of docetaxel as well as the IC50 value. After determining the effect of leptin on TAMs, the conditioned medium with an appropriate concentration of docetaxel was collected to treat the breast cancer cells, and flow cytometry was used to detect the cell cycle distribution and apoptosis in different treatment groups. Interleukin 8 (IL-8) expression was detected using ELISA and western blot assay. The IL-8 antibody was used to neutralize IL-8, and invasion and scratch assays were used to detect changes in invasion and migration of breast cancer cells. Statistical analysis was performed using GraphPad Prism 9.0 and SPSS 22.0. It was revealed that the apoptotic rate of MDA-MB-231 cells in the leptin-treated TAMs group was lower than that in other groups. The expression of IL-8 was notably elevated in the group treated with leptin-activated TAMs compared with that in the other groups. The neutralization of IL-8 resulted in a significant reduction in the invasive migration of MDA-MB-231 cells compared with that in the non-neutralized group.

Lipocalin-2 promotes adipose-macrophage interactions to shape peripheral and central inflammatory responses in experimental autoimmune encephalomyelitis

OBJECTIVE

Accumulating evidence suggests that dysfunctional adipose tissue (AT) plays a major role in the risk of developing multiple sclerosis (MS), the most common immune-mediated and demyelinating disease of the central nervous system. However, the contribution of adipose tissue to the etiology and progression of MS is still obscure. This study aimed at deciphering the responses of AT in experimental autoimmune encephalomyelitis (EAE), the best characterized animal model of MS.

RESULTS AND METHODS

We observed a significant AT loss in EAE mice at the onset of disease, with a significant infiltration of M1-like macrophages and fibrosis in the AT, resembling a cachectic phenotype. Through an integrative and multilayered approach, we identified lipocalin2 (LCN2) as the key molecule released by dysfunctional adipocytes through redox-dependent mechanism. Adipose-derived LCN2 shapes the pro-inflammatory macrophage phenotype, and the genetic deficiency of LCN2 specifically in AT reduced weight loss as well as inflammatory macrophage infiltration in spinal cord in EAE mice. Mature adipocytes downregulating LCN2 reduced lipolytic response to inflammatory stimuli (e.g. TNFα) through an ATGL-mediated mechanism.

CONCLUSIONS

Overall data highlighted a role LCN2 in exacerbating inflammatory phenotype in EAE model, suggesting a pathogenic role of dysfunctional AT in MS.

Impact of intestinal microenvironments in obesity and bariatric surgery on shaping macrophages

Obesity is associated with alterations in tissue composition, systemic cellular metabolism, and low-grade chronic inflammation. Macrophages are heterogenous innate immune cells ubiquitously localized throughout the body and are key components of tissue homeostasis, inflammation, wound healing, and various disease states. Macrophages are highly plastic and can switch their phenotypic polarization and change function in response to their local environments. Here, we discuss how obesity alters the intestinal microenvironment and potential key factors that can influence intestinal macrophages as well as macrophages in other organs, including adipose tissue and hematopoietic organs. As bariatric surgery can induce metabolic adaptation systemically, we discuss the potential mechanisms through which bariatric surgery reshapes macrophages in obesity.

Functional polarization of tumor-associated macrophages dictated by metabolic reprogramming

Macrophages are highly plastic in different tissues and can differentiate into functional subpopulations under different stimuli. Tumor-associated macrophages (TAMs) are one of the most important innate immune cells implicated in the establishment of an immunosuppressive tumor microenvironment (TME). Recent evidence pinpoints the critical role of metabolic reprogramming in dictating pro-tumorigenic functions of TAMs. Both tumor cells and macrophages undergo metabolic reprogramming to meet energy demands in the TME. Understanding the metabolic rewiring in TAMs can shed light on immune escape mechanisms and provide insights into repolarizing TAMs towards anti-tumorigenic function. Here, we discuss how metabolism impinges on the functional divergence of macrophages and its relevance to macrophage polarization in the TME.

Host obesity alters the ovarian tumor immune microenvironment and impacts response to standard of care chemotherapy

BACKGROUND

The majority of women with epithelial ovarian cancer (OvCa) are diagnosed with metastatic disease, resulting in a poor 5-year survival of 31%. Obesity is a recognized non-infectious pandemic that increases OvCa incidence, enhances metastatic success and reduces survival. We have previously demonstrated a link between obesity and OvCa metastatic success in a diet-induced obesity mouse model wherein a significantly enhanced tumor burden was associated with a decreased M1/M2 tumor-associated macrophage ratio (Liu Y et al. Can, Res. 2015; 75:5046-57).

METHODS

The objective of this study was to use pre-clinical murine models of diet-induced obesity to evaluate the effect of a high fat diet (HFD) on response to standard of care chemotherapy and to assess obesity-associated changes in the tumor microenvironment. Archived tumor tissues from ovarian cancer patients of defined body mass index (BMI) were also evaluated using multiplexed immunofluorescence analysis of immune markers.

RESULTS

We observed a significantly diminished response to standard of care paclitaxel/carboplatin chemotherapy in HFD mice relative to low fat diet (LFD) controls. A corresponding decrease in the M1/M2 macrophage ratio and enhanced tumor fibrosis were observed both in murine DIO studies and in human tumors from women with BMI > 30.

CONCLUSIONS

Our data suggest that the reported negative impact of obesity on OvCa patient survival may be due in part to the effect of the altered M1/M2 tumor-associated macrophage ratio and enhanced fibrosis on chemosensitivity. These data demonstrate a contribution of host obesity to ovarian tumor progression and therapeutic response and support future combination strategies targeting macrophage polarization and/or fibrosis in the obese host.

Bariatric surgery in the prevention of obesity-associated cancers: mechanistic implications

Obesity is associated with an increased risk of at least 13 different cancers, as well as worse cancer outcomes and increased cancer mortality. As rates continue to rise both in the United States and worldwide, obesity is poised to become the leading lifestyle-related risk factor for cancer. Currently, the most effective treatment for patients with severe obesity is bariatric surgery. Multiple cohort studies have demonstrated a consistent >30% decreased risk of cancer incidence in women, but not men, following bariatric surgery. However, the physiologic mechanisms driving obesity-associated cancer and the cancer-protective effect of bariatric surgery are not clearly defined. In this review, we highlight emerging concepts in the mechanistic understanding of obesity-associated cancer. Evidence from both human studies and preclinical animal models suggest that obesity drives carcinogenesis through dysregulation of systemic metabolism, immune dysfunction, and an altered gut microbiome. Additionally, we present related findings to suggest that bariatric surgery may disrupt and even reverse many of these mechanisms. Finally, we discuss the use of preclinical bariatric surgery animal models in the study of cancer biology. The prevention of cancer is emerging as an important indication for bariatric surgery. Elucidating the mechanisms through which bariatric surgery limits carcinogenesis is critical to developing a variety of interventions that intercept obesity-driven cancer.

Outcomes in breast cancer-does ethnicity matter?

Ethnic or racial differences in breast cancer (BC) survival outcomes have been reported, but current data are largely restricted to comparisons between African Americans and non-Hispanic whites. Most analyses have traditionally been based on self-reported race which may not always be accurate, or are oversimplified in their classification. With increasing globalization, quantification of the genetic ancestry from genomic data may offer a solution to infer the complex makeup from admixture of races. Focusing on the larger and the latest studies, we will discuss recent findings on the differing host and tumor biology that may be driving these disparities, in addition to the extrinsic environmental or lifestyle factors. Socioeconomic disparities with lower cancer literacy may lead to late presentation, poorer adherence to treatment, and other lifestyle factors such as unhealthy diet, obesity, and inadequate physical activity. These hardships may also result in greater allostatic load, which is in turn associated with aggressive BC features in disadvantaged populations. Epigenetic reprogramming may mediate the effects of the environment or lifestyle factors on gene expression, with ensuing differences in BC characteristics and outcome. There is increasing evidence that germline genetics can influence somatic gene alterations or expression, as well as modulate the tumor or immune microenvironment. Although the precise mechanisms remain elusive, this may account for the varying distribution of different BC subtypes across ethnicities. These gaps in our knowledge highlight the need to interrogate the multiomics landscape of BC in diverse populations, ideally in large-scale collaborative settings with standardized methodology for the comparisons to be statistically robust. Together with improving BC awareness and access to good quality health care, a holistic approach with insights of the biological underpinnings is much needed to eradicate ethnic disparities in BC outcomes.

Knocking down GALNT6 promotes pyroptosis of pancreatic ductal adenocarcinoma cells through NF-κB/NLRP3/GSDMD and GSDME signaling pathway

Background

Pancreatic ductal adenocarcinoma (PDAC), the most prevalent type of pancreatic cancer, is a highly lethal malignancy with poor prognosis. Polypeptide N-acetylgalactosaminyltransferase-6 (GALNT6) is frequently overexpressed in PDAC. However, the role of GALNT6 in the PDAC remains unclear.

Methods

The expression of GALNT6 in pancreatic cancer and normal tissues were analyzed by bioinformatic analyses and immunohistochemistry. CCK8 and colony formation were used to detect cell proliferation. Flow cytometry was applied to detect cell cycle.The pyroptosis was detected by scanning electron microscopy. The mRNA expression was detected by qRT-PCR. The protein expression and localization were detected by western blot and immunofluorescence assay. ELISA was used to detect the levels of inflammatory factors.

Results

The expression of GALNT6 was associated with advanced tumor stage, and had an area under curve (AUC) value of 0.919 in pancreatic cancer based on the cancer genome atlas (TCGA) dataset. Knockdown of GALNT6 inhibited cell proliferation, migration, invasion and cell cycle arrest of PDAC cells. Meanwhile, knockdown of GALNT6 increased the expression levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin-18 (IL-18), the release of inflammasome and an increasing of Gasdermin D (GSDMD), N-terminal of GSDMD (GSDMD-N), Gasdermin E (GSDME) and N-terminal of GSDME (GSDME-N) in PDAC cells. GALNT6 suppressed the expression of NOD-like receptor thermal protein domain associated protein 3 (NLRP3) and GSDMD by glycosylation of NF-κB and inhibiting the nucleus localization of NF-κB. Additionally, GALNT6 promotes the degradation of GSDME by O-glycosylation.

Conclusion

We found that GALNT6 is highly expressed in pancreatic cancer and plays a carcinogenic role. The results suggested that GALNT6 regulates the pyroptosis of PDAC cells through NF-κB/NLRP3/GSDMD and GSDME signaling. Our study might provides novel insights into the roles of GALNT6 in PDAC progression.

Body mass index, C-reactive protein, and pancreatic cancer: A Mendelian randomization analysis to investigate causal pathways

Aim

To explore whether C-reactive protein (CRP) mediates the risk of body mass index (BMI) in pancreatic cancer (PC) and calculate the mediate proportion of CRP in this possible mechanism.

Methods

Based on two-sample Mendelian randomization (TSMR), a two-step Mendelian randomization (TM) model was conducted to determine whether CRP was a mediator of the causal relationship between BMI and PC. The multivariable Mendelian randomization (MVMR) study was designed for mediating analysis and to calculate the mediating proportion mediated by CRP.

Results

BMI has a positive causal relationship with PC (n = 393 SNPs, OR = 1.484, 95% CI: 1.021-2.157, p< 0.05). BMI has a positive causal relationship with CRP (n = 179 SNPs, OR = 1.393, 95% CI: 1.320-1.469, p< 0.05). CRP has a positive causal relationship with PC (n = 54 SNPs, OR = 1.348, 95% CI: 1.004-1.809, p< 0.05). After adjusting CRP, BMI has no causal relationship with PC (n = 334 SNPs, OR = 1.341, 95% CI: 0.884-2.037, p< 0.05). After adjusting BMI, there was still a positive causal relationship between CRP and PC (n = 334 SNPs, OR = 1.441, 95% CI: 1.064-1.950, p< 0.05). The mediating effect of CRP was 29%.

Conclusions

In clinical practice, while actively advocating for weight loss among obese patients, we should focus on chronic inflammation levels in obese patients as well. In addition, anti-inflammatory dietary patterns and appropriate physical activity are important in preventing PC.