Adenosine receptor A2b confers ovarian cancer survival and PARP inhibitor resistance through IL-6-STAT3 signalling.

Ovarian cancer is the deadliest gynecologic cancer worldwide, and the therapeutic options are limited. PARP inhibitor (PARPi) represents an effective therapeutic strategy and has been approved for maintenance therapy. However, the intrinsic or acquired resistance to PARPi becomes a big challenge. To investigate the mechanisms for PARPi resistance, we analysed public databases and established Olaparib-resistant ovarian cancer cells for exploration. Our results showed that the inflammatory pathway and adenosine receptor A2b (Adora2b/A2B ) expression were significantly increased in Olaparib-resistant cells. A2B was highly expressed in recurrent ovarian tumours and negatively correlated with the clinical outcomes in cancer patients. Olaparib treatment enhanced A2B expression through NF-κB activation. The elevated A2B contributed to Olaparib resistance by sensing adenosine signal and promoting tumour cell survival, growth and migration via IL-6-STAT3 signalling. Therefore, inhibition of A2B -IL-6-STAT3 axis could overcome Olaparib resistance and synergize with Olaparib to reduce cancer cell growth and lead to cell death. Our findings reveal a critical role of A2B signalling in mediating PARPi resistance independent of DNA damage repair, providing insights into developing novel therapies in ovarian cancers.

IL-6/STAT3 axis dictates the PNPLA3-mediated susceptibility to non-alcoholic fatty liver disease.

BACKGROUND & AIMS: A number of genetic polymorphisms have been associated with susceptibility to or protection against non-alcoholic fatty liver disease (NAFLD), but the underlying mechanisms remain unknown. Here, we focused on the rs738409 C>G single nucleotide polymorphism (SNP), which produces the I148M variant of patatin-like phospholipase domain-containing protein 3 (PNPLA3) and is strongly associated with NAFLD. METHODS: To enable mechanistic dissection, we developed a human pluripotent stem cell (hPSC)-derived multicellular liver culture by incorporating hPSC-derived hepatocytes, hepatic stellate cells, and macrophages. We first applied this liver culture to model NAFLD by utilising a lipotoxic milieu reflecting the circulating levels of disease risk factors in affected individuals. We then created an isogenic pair of liver cultures differing only at rs738049 and compared NAFLD phenotype development. RESULTS: Our hPSC-derived liver culture recapitulated many key characteristics of NAFLD development and progression including lipid accumulation and oxidative stress, inflammatory response, and stellate cell activation. Under the lipotoxic conditions, the I148M variant caused the enhanced development of NAFLD phenotypes. These differences were associated with elevated IL-6/signal transducer and activator of transcription 3 (STAT3) activity in liver cultures, consistent with transcriptomic data of liver biopsies from individuals carrying the rs738409 SNP. Dampening IL-6/STAT3 activity alleviated the I148M-mediated susceptibility to NAFLD, whereas boosting it in wild-type liver cultures enhanced NAFLD development. Finally, we attributed this elevated IL-6/STAT3 activity in liver cultures carrying the rs738409 SNP to increased NF-κB activity. CONCLUSIONS: Our study thus reveals a potential causal link between elevated IL-6/STAT3 activity and 148M-mediated susceptibility to NAFLD. IMPACT AND IMPLICATIONS: An increasing number of genetic variants manifest in non-alcoholic fatty liver disease (NAFLD) development and progression; however, the underlying mechanisms remain elusive. To study these variants in human-relevant systems, we developed an induced pluripotent stem cell-derived multicellular liver culture and focused on a common genetic variant (i.e. rs738409 in PNPLA3). Our findings not only provide mechanistic insight, but also a potential therapeutic strategy for NAFLD driven by this genetic variant in PNPLA3. Our liver culture is therefore a useful platform for exploring genetic variants in NAFLD development.

LRP5 promotes cancer stem cell traits and chemoresistance in colorectal cancer.

The overactivation of canonical Wnt/ß-catenin pathway and the maintenance of cancer stem cells (CSCs) are essential for the onset and malignant progression of most human cancers. However, their regulatory mechanism in colorectal cancer (CRC) has not yet been well demonstrated. Low-density lipoprotein receptor-related protein 5 (LRP5) has been identified as an indispensable co-receptor with frizzled family members for the canonical Wnt/ß-catenin signal transduction. Herein, we show that activation of LRP5 gene promotes CSCs-like phenotypes, including tumorigenicity and drug resistance in CRC cells, through activating the canonical Wnt/ß-catenin and IL-6/STAT3 signalling pathways. Clinically, the expression of LRP5 is upregulated in human CRC tissues and closely associated with clinical stages of patients with CRC. Further analysis showed silencing of endogenous LRP5 gene is sufficient to suppress the CSCs-like phenotypes of CRC through inhibiting these two pathways. In conclusion, our findings not only reveal a regulatory cross-talk between canonical Wnt/ß-catenin signalling pathway, IL-6/STAT3 signalling pathway and CD133-related stemness that promote the malignant behaviour of CRC, but also provide a valuable target for the diagnosis and treatment of CRC.

Cytarabine-induced TNFα promotes the expansion and suppressive functions of myeloid-derived suppressor cells in acute myeloid leukaemia.

Acute myeloid leukaemia (AML) is very common haematopoietic malignancies with poor prognosis. Chemotherapy is still a mainstay therapy for AML patients. AML microenvironment plays critical roles in therapy response. However, the role of chemotherapy in AML microenvironment is poorly understood. In this study, we report that cytarabine (AraC)-triggered TNFα from AML cells expanded myeloid-derived suppressor cells (MDSCs) and enhanced MDSC functions and survival through activating IL-6/STAT3 and NFκB pathways. Blockade of TNFα in conditioned medium-derived AraC-treated AML cells (AraC_CM) impaired MDSC expansion and functions, reduced IL-6 secretion and the level of activated STAT3. Inhibiting IL6 or STAT3 abrogated AraC_CM-mediated MDSC suppressive function. Additionally, inhibiting TNFα also impaired AraC_CM-mediated NFκB activation. Blocking NFκB activation reduced MDSC viability induced by AraC_CM. Together, these results provided a role of AraC-induced TNFα in MDSC expansion and functions and suggest that targeting TNFα may benefit AML patients to current anticancer strategies by blocking MDSC-mediated immunosuppression.

Kartogenin mediates cartilage regeneration by stimulating the IL-6/Stat3-dependent proliferation of cartilage stem/progenitor cells.

A decrease in the number of endogenous stem cells in cartilage is regarded as the cause of cartilage degeneration. Kartogenin (KGN) is known to induce chondrogenesis of cartilage stem/progenitor cells (CSPCs). Using CSPCs isolated from rat cartilage, we analysed changes in the transcriptome after treatment with KGN in vitro. An animal model of destabilization of the medial meniscus (DMM) was then used to identify the effect of intra-articular (IA) KGN injection on CSPC proliferation in vivo. Here, we demonstrated that KGN promoted the proliferation of CSPCs isolated from cartilage. The percentage of G2-M phase cells in the KGN-treated group reached over 10%, nearly twice that in the control group. Transcriptomic profiling of rat CSPCs revealed significant changes in KGN-treated samples compared to control samples. The gene expression levels of IL-6 and its coreceptor Gp130 were much higher in the KGN-treated group than in the control group. Phosphorylation of the IL-6 downstream molecule Stat3 was enhanced via KGN stimulation. The DMM animal model showed increased articular cartilage thickness after IA KGN injection. IHC staining also demonstrated upregulation of Stat3 phosphorylation and enhanced distribution of CD44+/CD105+ cells in cartilage following IA KGN injection. Thus, our data suggested that KGN promoted cartilage regeneration at least partially by stimulating IL-6/Stat3-dependent proliferation.

The anti-inflammatory effects of Hedyotis diffusa Willd on SLE with STAT3 as a key target.

ETHNOPHARMACOLOGICAL RELEVANCE: Hedyotis diffusa Willd, also named Scleromitrion diffusum (Willd.) R.J. Wang, is one medical herb, which has been traditionally used by the She nationality in China. And H. diffusa represents a beneficial effect on Systemic lupus erythematosus (SLE) treatment in clinic. AIM OF THE STUDY: The underlying mechanisms of the protective effects of H. diffusa on SLE remain unclear. In this study, we treated MRL/lpr mice with H. diffusa water extract (HDW) to assess its therapeutic effects and verified its regulating signalling pathway through cytological experiments. MATERIALS AND METHODS: In the present study, the constituents of HDW were analysed through ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) and SCIEX OS software. The protective activity and underlying mechanisms were studied in a MRL/lpr lupus mouse model. The blood cells, autoantibodies, metabolites and the cytokines in serum were identified with a hematology analyzer, specific ELISA kit, GC/MS system and cytometric assays. The histological and immunohistochemical analysis were engaged in the morphologic, and the expression and translocation of the crucial protein observation. The dual luciferase reporter assay was applied to identifying the regulative activity of HDW. The transcription and translation expression of the protein was studied by real-time PCR and Western blot assays. The network pharmacology analysis was employed to predict the IL-6/STAT3 pathway regulators and the screen the STAT3 inhibitors in HDW. RESULTS: The results revealed the capability of HDW to attenuate the production of autoantibodies, secretion of inflammatory cytokines (IL-6 and IFN-γ), and suppressed the IgG and C3 deposition, the development of glomerular lesions in MRL/lpr mice. Serum metabolomics study showed the improvement in serum metabolites, especially aminoacyl-tRNA biosynthesis, by HDW. IL-6 was clarified to be highly associated with the significantly changed metabolites in network analysis. We further demonstrated the effects of HDW on the IL-6/STAT3 pathway in vivo and in vitro. CONCLUSIONS: This study suggested that HDW exerts a therapeutic effect in SLE model mice by suppressing the IL-6/STAT3 pathway.