Brown adipocytes promote epithelial mesenchymal transition of neuroblastoma cells by inducing PPAR-γ/UCP2 expression

Roles of PPAR activation in cancer therapeutic resistance: Implications for combination therapy and drug development

Therapeutic resistance is a major obstacle to successful treatment or effective containment of cancer. Peroxisome proliferator-activated receptors (PPARs) play an essential role in regulating energy homeostasis and determining cell fate. Despite of the pleiotropic roles of PPARs in cancer, numerous studies have suggested their intricate relationship with therapeutic resistance in cancer. In this review, we provided an overview of the roles of excessively activated PPARs in promoting resistance to modern anti-cancer treatments, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy. The mechanisms through which activated PPARs contribute to therapeutic resistance in most cases include metabolic reprogramming, anti-oxidant defense, anti-apoptosis signaling, proliferation-promoting pathways, and induction of an immunosuppressive tumor microenvironment. In addition, we discussed the mechanisms through which activated PPARs lead to multidrug resistance in cancer, including drug efflux, epithelial-to-mesenchymal transition, and acquisition and maintenance of the cancer stem cell phenotype. Preliminary studies investigating the effect of combination therapies with PPAR antagonists have suggested the potential of these antagonists in reversing resistance and facilitating sustained cancer management. These findings will provide a valuable reference for further research on and clinical translation of PPAR-targeting treatment strategies.

Transmembrane serine protease 6, a novel target for inhibition of neuronal tumor growth

Transmembrane serine protease 6 (Tmprss6) has been correlated with the occurrence and progression of tumors, but any specific molecular mechanism linking the enzyme to oncogenesis has remained elusive thus far. In the present study, we found that Tmprss6 markedly inhibited mouse neuroblastoma N2a (neuro-2a) cell proliferation and tumor growth in nude mice. Tmprss6 inhibits Smad1/5/8 phosphorylation by cleaving the bone morphogenetic protein (BMP) co-receptor, hemojuvelin (HJV). Ordinarily, phosphorylated Smad1/5/8 binds to Smad4 for nuclear translocation, which stimulates the expression of hepcidin, ultimately decreasing the export of iron through ferroportin 1 (FPN1). The decrease in cellular iron levels in neuro-2a cells with elevated Tmprss6 expression limited the availability of the metal forribo nucleotide reductase activity, thereby arresting the cell cycle prior to S phase. Interestingly, Smad4 promoted nuclear translocation of activating transcription factor 3 (ATF3) to activate the p38 mitogen-activated protein kinases signaling pathway by binding to ATF3, inducing apoptosis of neuro-2a cells and inhibiting tumor growth. Disruption of ATF3 expression significantly decreased apoptosis in Tmprss6 overexpressed neuro-2a cells. Our study describes a mechanism whereby Tmprss6 regulates the cell cycle and apoptosis. Thus, we propose Tmprss6 as a candidate target for inhibiting neuronal tumor growth.

[Aumolertinib inhibits proliferation, invasion and migration and promotes apoptosis of neuroblastoma cells by downregulating MMP2 and MMP9 expression]

OBJECTIVE

To investigate the effects of aumolertinib, an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), on biological behaviors of neuroblastoma SH-SY5Y cells.

METHODS

CCK-8 assay, colony-forming assay, Transwell assay and flow cytometry were used to assess the effects of 2, 4 and 8 μmol/L aumolertinib on proliferation, survival, migration, invasion and apoptosis of SH-SY5Y cells, and the changes in ultrastructure of the cells were observed using transmission electron microscopy. The protein expressions of Bax, Bcl-2, E-cadherin, vimentin, MMP2, and MMP9 in the treated cells were detected using Western blotting. A nude mouse model bearing subcutaneous SH-SY5Y cell xenograft were treated with aumolertinib (15 mg/kg) or cyclophosphamide (20 mg/kg), and the tumor volume and body mass changes was measured. HE staining was used to observe adverse effects of the treatment on the heart, liver, spleen, lungs and kidneys.

RESULTS

Aumolertinib significantly inhibited the proliferation and viability of SH-SY5Y cells (P<0.05) with IC50 of 5.004, 3.728 and 3.228 µmol/L at 24, 48 and 72 h, respectively. Aumolertinib treatment induced obvious apoptosis of the cells, which showed characteristic morphological changes of apoptosis under transmission electron microscope. The treatment also inhibited the invasion and migration abilities of SH-SY5Y cells (P<0.01), up-regulated the expression levels of E-cadherin and Bax and lowered the expression levels of Bcl-2, vimentin, MMP2 and MMP9 (P<0.05). In the nude mouse models, treatment with aumolertinib effectively inhibited the growth of neuroblastoma without causing significant toxicity to the vital organs.

CONCLUSION

Aumolertinib inhibits proliferation, survival, invasion and migration and induces apoptosis in SH-SY5Y cells by downregulating MMP2 and MMP9 expression.

Metabolic crosstalk between thermogenic adipocyte and cancer cell: Dysfunction and therapeutics

As one of the largest endocrine organs with a wide distribution in organisms, adipose tissue secretes multiple adipokines, cytokines, metabolites, and exosomes to promote tumour development. Elaborating the crosstalk between cancer cells and adipocytes provides a tissue-level perspective of cancer progression, which reflects the heterogeneity and complexity of human tumours. Three main types of adipose tissues, white, brown, and beige adipose tissue, have been described. Thermogenic capacity is a prominent characteristic of brown and beige adipocytes. Most studies so far mainly focus on the contribution of white adipocytes to the tumour microenvironment. However, the role of thermogenic adipose tissue in malignant cancer behaviour has been largely overlooked. Recently, emerging evidence suggests that beige/brown adipocytes play a key role in the development and progression of various cancers. This review focuses on the bidirectional communication between tumour cells and thermogenic adipocytes and the therapeutic strategies to disrupt this interaction.