FABP5 regulates lipid metabolism to facilitate pancreatic neuroendocrine neoplasms progression via FASN mediated Wnt/β-catenin pathway

Differences in proteomic profiles and immunomodulatory activity of goat and cow milk fat globule membrane

This study aimed to clarify the composition and bioactivity differences between goat and cow milk fat globule membrane (MFGM) protein by proteomic, and the immunomodulatory activity of MFGM proteins was further evaluated by using mouse splenic lymphocytes in vitro. A total of 257 MFGM proteins showed significant differences between goat and cow milk. The upregulated and unique MFGM proteins in goat milk were significantly enriched in the positive regulation of immune response, negative regulation of Interleukin-5 (IL-5) secretion, and involved in nucleotide-binding oligomerization domain (NOD)-like receptor signaling. The contents of IL-2 and Interferon-γ in the supernatant of spleen lymphocytes treated with goat MFGM proteins were much higher than those of IL-4 and IL-5, suggesting a Th1-skewed immune response. These results revealed that goat MFGM proteins could possess better immunomodulatory effects as compared to cow milk. Our findings may provide new insights to elucidate the physiological functions and nutritional of goat milk.

Exploring the therapeutic potential of simvastatin in pancreatic neuroendocrine neoplasms: insights into cell cycle regulation and apoptosis

Background

Pancreatic neuroendocrine neoplasm (pNEN) poses significant challenges in clinical management due to their heterogeneity and limited treatment options. In this study, we investigated the potential of simvastatin (SIM) as an anti-tumor agent in pNEN.

Methods

We conducted cell culture experiments using QGP-1 and BON-1 cell lines and assessed cell viability, proliferation, migration, and invasion following SIM treatment. To further validate our findings, we performed in vivo experiments using a mouse xenograft model. Additionally, we investigated the underlying molecular mechanisms by analyzing changes in cell cycle progression, apoptosis, and signaling pathways.

Results

SIM treatment suppresses pNEN growth both in vitro and in vivo, and led to G1 phase arrest in QGP-1 cells. In contrast, SIM affected both the G1-S and G2-M phase transitions in the BON-1 cell line and induced apoptosis, indicating diverse mechanisms of action. Furthermore, SIM treatment resulted in decreased expression of mutant p53 (mutp53) in BON-1 cells, suggesting a potential therapeutic strategy targeting mutp53. Modulation of the MAPK pathway was also implicated in QGP-1 cells.

Conclusions

Our study highlights SIM as a promising candidate for pNEN treatment by inducing cell cycle arrest or apoptosis, potentially through the p53 and MAPK pathways. Further research is warranted to fully elucidate SIM's mechanisms of action and evaluate its therapeutic potential in clinical settings.

SCG2 and CPE may be novel markers for the identification of pancreatic neuroendocrine tumors and solid pseudopapillary neoplasms

Background

Distinguishing pancreatic neuroendocrine tumors (pNETs) from solid pseudopapillary neoplasms (SPNs) is challenging, primarily due to their overlapping pathological characteristics. To address this, our study aims to identify and validate novel biomarkers that effectively differentiate between these two conditions. We focus on the exploration of new immunohistochemical markers to enhance this distinction.

Methods

In this study, we analyzed genetic variations in pNETs and SPNs using the GSE43795 dataset from the Gene Expression Omnibus (GEO) database. Our approach was to identify genes with higher expression in pNETs compared to SPNs and normal pancreatic tissues. We conducted enrichment analyses to understand the functions of these genes. Furthermore, protein-protein interaction (PPI) network analysis was utilized to identify key genes associated with pNETs. Our sample consisted of 163 pancreatic tumor specimens, comprising 78 pNETs and 85 SPNs. We also collected clinicopathological data and used immunohistochemistry to measure the expression levels of these key genes.

Results

The enrichment analysis revealed that genes overexpressed in pNETs were mainly involved in signal release, vesicle transport, and ion pathway activation, playing significant roles in endocrine processes like insulin secretion, dopamine synapses, and circadian rhythm regulation. The PPI analysis identified secretogranin II (SCG2), carboxypeptidase E (CPE), and chromogranin A (CgA, CHGA) as key markers for differentiating pNETs from SPNs. Immunohistochemical validation of these markers demonstrated high sensitivity (SCG2: 98.7%, CPE: 97.4%) and specificity (100%), indicating their superior discriminative power compared to traditional markers like CgA, β-catenin, lymphoid enhancer-binding factor 1 (LEF1), and vimentin.

Conclusions

Our study indicates that SCG2 and CPE are effective, novel immunohistochemical biomarkers for differentiating pNETs from SPNs.

Hypoxia exosome derived CEACAM5 promotes tumor-associated macrophages M2 polarization to accelerate pancreatic neuroendocrine tumors metastasis via MMP9

Exosomes play significant roles in the communications between tumor cells and tumor microenvironment. However, the specific mechanisms by which exosomes modulate tumor development under hypoxia in pancreatic neuroendocrine tumors (pNETs) are not well understood. This study aims to investigate these mechanisms and made several important discoveries. We found that hypoxic exosomes derived from pNETs cells can activate tumor-associated macrophages (TAM) to the M2 phenotype, in turn, the M2-polarized TAM, facilitate the migration and invasion of pNETs cells. Further investigation revealed that CEACAM5, a protein highly expressed in hypoxic pNETs cells, is enriched in hypoxic pNETs cell-derived exosomes. Hypoxic exosomal CEACAM5 was observed to induce M2 polarization of TAM through activation of the MAPK signaling pathway. Coculturing pNETs cells with TAM or treated with hypoxic exosomes enhanced the metastatic capacity of pNETs cells. In conclusion, these findings suggest that pNETs cells generate CEACAM5-rich exosomes in a hypoxic microenvironment, which in turn polarize TAM promote malignant invasion of pNETs cells. Targeting exosomal CEACAM5 could potentially serve as a diagnostic and therapeutic strategy for pNETs.

Hypoxic tumor-derived exosomal miR-4488 induces macrophage M2 polarization to promote liver metastasis of pancreatic neuroendocrine neoplasm through RTN3/FABP5 mediated fatty acid oxidation

Tumor-associated macrophages (TAMs) represent a predominant cellular component within the tumor microenvironment (TME) of pancreatic neuroendocrine neoplasms (pNENs). There is a growing body of evidence highlighting the critical role of exosomes in facilitating communication between tumor cells and TAMs, thereby contributing to the establishment of the premetastatic niche. Nonetheless, the specific mechanisms through which exosomes derived from tumor cells influence macrophage polarization under hypoxic conditions in pNENs, and the manner in which these interactions support cancer metastasis, remain largely unexplored. Recognizing the capacity of exosomes to transfer miRNAs that can modify cellular behaviors, our research identified a significant overexpression of miR-4488 in exosomes derived from hypoxic pNEN cells. Furthermore, we observed that macrophages that absorbed circulating exosomal miR-4488 underwent M2-like polarization. Our investigations revealed that miR-4488 promotes M2-like polarization by directly targeting and suppressing RTN3 in macrophages. This suppression of RTN3 enhances fatty acid oxidation and activates the PI3K/AKT/mTOR signaling pathway through the interaction and downregulation of FABP5. Additionally, M2 polarized macrophages contribute to the formation of the premetastatic niche and advance pNENs metastasis by releasing MMP2, thereby establishing a positive feedback loop involving miR-4488, RTN3, FABP5, and MMP2 in pNEN cells. Together, these findings shed light on the role of exosomal miRNAs from hypoxic pNEN cells in mediating interactions between pNEN cells and intrahepatic macrophages, suggesting that miR-4488 holds potential as a valuable biomarker and therapeutic target for pNENs.

TRIM45 facilitates NASH-progressed HCC by promoting fatty acid synthesis via catalyzing FABP5 ubiquitylation

Non-alcoholic steatohepatitis (NASH) is rapidly surpassing viral hepatitis as the primary cause of hepatocellular carcinoma (HCC). However, understanding of NASH-progressed HCC remains poor, which might impede HCC diagnosis and therapy. In this study, we aim to identify shared transcriptional changes between NASH and HCC, of which we focused on E3 ligase TRIM45. We found TRIM45 exacerbates HCC cells proliferation and metastasis in vitro and in vivo. Further transcriptome analysis revealed TRIM45 predominantly affects fatty acid metabolism and oleic acid restored impaired proliferation and metastasis of TRIM45-deficient HCC cells. IP-tandem mass spectrum and FABP5 depriving experiment indicated that TRIM45 enhance fatty acid synthesis depending on FABP5 presence. Interestingly, we found TRIM45 directly added K33-type and K63-type poly-ubiquitin chains to FABP5 NLS domain, which ultimately promoted FABP5 nuclear translocation. Nuclear FABP5 interacted with PPARγ to facilitate downstream lipid synthesis gene expression. We observed TRIM45 accelerated NASH-to-HCC transition and exacerbated both NASH and NASH-HCC with the enhanced fatty acid production in vivo. Moreover, high concentration of fatty acid increased TRIM45 expression. The established mechanism was substantiated by gene expression correlation in TCGA-LIHC. Collectively, our research revealed a common lipid reprograming process in NASH and HCC and identified the cyclical amplification of the TRIM45-FABP5-PPARγ-fatty acid axis. This signaling pathway offers potential therapeutic targets for therapeutic intervention in NASH and NASH-progressed HCC.

Hypoxia upregulating ACSS2 enhances lipid metabolism reprogramming through HMGCS1 mediated PI3K/AKT/mTOR pathway to promote the progression of pancreatic neuroendocrine neoplasms

BACKGROUND

Pancreatic neuroendocrine neoplasms (pNENs) are relatively rare. Hypoxia and lipid metabolism-related gene acetyl-CoA synthetase 2 (ACSS2) is involved in tumor progression, but its role in pNENs is not revealed. This study showed that hypoxia can upregulate ACSS2, which plays an important role in the occurrence and development of pNENs through lipid metabolism reprogramming. However, the precise role and mechanisms of ACSS2 in pNENs remain unknown.

METHODS

mRNA and protein levels of ACSS2 and 3-hydroxy-3-methylglutaryl-CoA synthase1 (HMGCS1) were detected using quantitative real-time PCR (qRT-PCR) and Western blotting (WB). The effects of ACSS2 and HMGCS1 on cell proliferation were examined using CCK-8, colony formation assay and EdU assay, and their effects on cell migration and invasion were examined using transwell assay. The interaction between ACSS2 and HMGCS1 was verified by Co-immunoprecipitation (Co-IP) experiments, and the functions of ACSS2 and HMGCS1 in vivo were determined by nude mouse xenografts.

RESULTS

We demonstrated that hypoxia can upregulate ACSS2 while hypoxia also promoted the progression of pNENs. ACSS2 was significantly upregulated in pNENs, and overexpression of ACSS2 promoted the progression of pNENs and knockdown of ACSS2 and ACSS2 inhibitor (ACSS2i) treatment inhibited the progression of pNENs. ACSS2 regulated lipid reprogramming and the PI3K/AKT/mTOR pathway in pNENs, and ACSS2 regulated lipid metabolism reprogramming through the PI3K/AKT/mTOR pathway. Co-IP experiments indicated that HMGCS1 interacted with ACSS2 in pNENs. Overexpression of HMGCS1 can reverse the enhanced lipid metabolism reprogramming and tumor-promoting effects of knockdown of ACSS2. Moreover, overexpression of HMGCS1 reversed the inhibitory effect of knockdown of ACSS2 on the PI3K/AKT/mTOR pathway.

CONCLUSION

Our study revealed that hypoxia can upregulate the lipid metabolism-related gene ACSS2, which plays a tumorigenic effect by regulating lipid metabolism through activating the PI3K/AKT/mTOR pathway. In addition, HMGCS1 can reverse the oncogenic effects of ACSS2, providing a new option for therapeutic strategy.