Background: Chemoresistance is a significant obstacle to the effective treatment of breast cancer (BC), resulting in more aggressive behavior and worse clinical outcome. The molecular mechanisms underlying breast cancer chemoresistance remain unclear. Our microarray analysis had identified the overexpression of a small molecular glycoprotein serglycin (SRGN) in multidrug-resistant BC cells. Here, we aimed to investigate the role of SRGN in chemoresistance of breast cancer and elucidate the underlying mechanisms. Methods: SRNG overexpression was identified using microarray analysis and its clinical relevance was analyzed. To investigate the role of SRGN, we performed various in vitro and in vivo studies, as well as characterization of serum and tissue samples from BC patients. Chemosensitivity measurement, gene expression interference, immunofluorescence staining, mammosphere assay, flow cytometry analysis, luciferase reporter assay, ChIP-qPCR, coimmunoprecipitation, and immunohistochemistry were performed to explore the potential functions and mechanisms of SRGN. Results: We confirmed overexpression of SRGN in chemoresistant BC cells and in serum and tissue samples from BC patients with poor response to chemotherapy. SRGN specifically predicted poor prognosis in BC patients receiving chemotherapy. Mechanistically, SRGN promoted chemoresistance both in vitro and in vivo by cross-talking with the transcriptional coactivator YES-associated protein (YAP) to maintain stemness in BC cells. Ectopic YAP expression restored the effects of SRGN knockdown. Inversely, YAP knockdown rescued the effects of SRGN overexpression. The secreted SRGN triggered ITGA5/FAK/CREB signaling to enhance YAP transcription. Reciprocally, YAP promoted SRGN transcription in a TEAD1-dependent manner to form a feed-forward circuit. Moreover, the YAP/RUNX1 complex promoted HDAC2 transcription to induce chemoresistance and stemness in BC cells. Importantly, the SRGN levels were positively correlated with the YAP and HDAC2 levels in chemoresistant BC tissues. YAP and HDAC2 acted downstream of SRNG and correlated with poor outcomes of BC patients receiving chemotherapy. Conclusions: Our findings clarify the roles and mechanisms of SRGN in mediating chemoresistance in breast cancer and suggest its use a potential biomarker for chemotherapeutic response. We believe that novel therapeutic strategies for breast cancer can be designed by targeting the signaling mediated by the crosstalk between SRGN and YAP.

Rationale: Hepatocellular carcinoma (HCC) has been increasingly recognized in nonalcoholic steatohepatitis (NASH) patients. Fibroblast growth factor 21 (FGF21) is reported to prevent NASH and delay HCC development. In this study, the effects of FGF21 on NASH progression and NASH-HCC transition and the potential mechanism(s) were investigated. Methods: NASH models and NASH-HCC models were established in FGF21Knockout (KO) mice to evaluate NASH-HCC transition. IL-17A signaling was investigated in the isolated hepatic parenchymal cells, splenocytes, and hepatocyte and HCC cell lines. Results: Lack of FGF21 caused significant up-regulation of the hepatocyte-derived IL-17A via Toll-like receptor 4 (TLR4) and NF-κB signaling. Restoration of FGF21 alleviated the high NAFLD activity score (NAS) and attenuated the TLR4-triggered hepatocyte-IL-17A expression. The HCC nodule number and tumor size were significantly alleviated by treatments of anti-IL-17A antibody. Conclusion: This study revealed a novel anti-inflammatory mechanism of FGF21 via inhibiting the hepatocyte-TLR4-IL-17A signaling in NASH-HCC models. The negative feedback loop on the hepatocyte-TLR4-IL-17A axis could be a potential anti-carcinogenetic mechanism for FGF21 to prevent NASH-HCC transition.

Background: The reciprocal repressive loop between ZEB1 and miRNAs has been extensively reported to play an important role in tumor progression and metastasis of various human tumor types. The aim of this study was to elucidate the role and the underlying mechanism of the double-negative feedback loop between ZEB1and miR-33a-5p in bone metastasis of prostate cancer (PCa). Methods: miR-33a-5p expression was examined in 40 bone metastatic and 165 non-bone metastatic PCa tissues by real-time PCR. Statistical analysis was performed to evaluate the clinical correlation between miR-33a-5p expression and clinicopathological characteristics, and overall and bone metastasis-free survival in PCa patients. The biological roles of miR-33a-5p in bone metastasis of PCa were investigated both by EMT and the Transwell assay in vitro, and by a mouse model of left cardiac ventricle inoculation in vivo. siRNA library, real-time PCR and chromatin immunoprecipitation (ChIP) were used to identify the underlying mechanism responsible for the decreased expression of miR-33a-5p in PCa. Bioinformatics analysis, Western blotting and luciferase reporter analysis were employed to examine the relationship between miR-33a-5p and its potential targets. Clinical correlation of miR-33a-5p with its targets was examined in human PCa tissues and primary PCa cells. Results: miR-33a-5p expression was downregulated in PCa tissues with bone metastasis and bone-derived cells, and low expression of miR-33a-5p strongly and positively correlated with advanced clinicopathological characteristics, and shorter overall and bone metastasis-free survival in PCa patients. Upregulating miR-33a-5p inhibited, while silencing miR-33a-5p promoted EMT, invasion and migration of PCa cells. Importantly, upregulating miR-33a-5p significantly repressed bone metastasis of PC-3 cells in vivo. Our results further revealed that recurrent ZEB1 upregulation induced by copy number gains transcriptionally inhibited miR-33a-5p expression, contributing to the reduced expression of miR-33a-5p in bone metastatic PCa tissues. In turn, miR-33a-5p formed a double negative feedback loop with ZEB1 in target-independent manner, which was dependent on TGF-β signaling. Finally, the clinical negative correlations of miR-33a-5p with ZEB1 expression and TGF-β signaling activity were demonstrated in PCa tissues and primary PCa cells. Conclusion: Our findings elucidated that copy number gains of ZEB1-triggered a TGF-β signaling-dependent miR-33a-5p-mediated negative feedback loop was highly relevant to the bone metastasis of PCa.

Background: Immune cells have essential auxiliary functions and influence clinical outcomes in cancer, with high immune infiltration being associated with improved clinical outcomes and better response to treatment in breast cancer (BC). However, studies to date have not fully considered the tumor-infiltrating immune cell (TIIC) landscape in tumors. This study investigated potential biomarkers based on TIICs to improve prognosis and treatment effect in BC. Results: We enrolled 5112 patients for analysis and used cell type identification by estimating relative subsets of RNA transcripts (CIBERSORT), a new computational algorithm, to quantify 22 TIICs in primary BC. From the results of univariate Cox regression, 12 immune cells were determined to be significantly related to the overall survival (OS) of BC patients. Furthermore, least absolute shrinkage and selection operator (LASSO) and multivariate Cox regression analyses were applied to construct an immune prognostic model based on six potential biomarkers. By dividing patients into low- and high-risk groups, a significant distinction in OS was found in the training cohort, with 20-year survival rates of 42.6% and 26.3%, respectively. Applying a similar protocol to validation and test cohorts, we found that OS was significantly shorter in the high-risk group than in the low-risk group, regardless of the molecular subtype of BC. Using the immune score model to predict the effect of BC patients to chemotherapy, the survival advantage for the low-risk group was evident among those who received chemotherapy, regardless of the chemotherapy regimen. In evaluating the predictive value of the nomogram, a decision curve showed better predictive accuracy than the standard tumor-node-metastasis (TNM) staging system. Conclusion: The immune cell infiltration-based immune score model can be effectively and efficiently used to predict the prognosis of BC patients as well as the effect of chemotherapy.

Purpose: To determine the role of UCH-L1 in regulating ERα expression, and to evaluate whether therapeutic targeting of UCH-L1 can enhance the efficacy of anti-estrogen therapy against breast cancer with loss or reduction of ERα. Methods: Expressions of UCH-L1 and ERα were examined in breast cancer cells and patient specimens. The associations between UCH-L1 and ERα, therapeutic response and prognosis in breast cancer patients were analyzed using multiple databases. The molecular pathways by which UCH-L1 regulates ERα were analyzed using immunoblotting, qRT-PCR, immunoprecipitation, ubiquitination, luciferase and ChIP assays. The effects of UCH-L1 inhibition on the efficacy of tamoxifen in ERα (-) breast cancer cells were tested both in vivo and in vitro. Results: UCH-L1 expression was conversely correlated with ERα status in breast cancer, and the negative regulatory effect of UCH-L1 on ERα was mediated by the deubiquitinase-mediated stability of EGFR, which suppresses ERα transcription. High expression of UCH-L1 was associated with poor therapeutic response and prognosis in patients with breast cancer. Up-regulation of ERα caused by UCH-L1 inhibition could significantly enhance the efficacy of tamoxifen and fulvestrant in ERα (-) breast cancer both in vivo and in vitro. Conclusions: Our results reveal an important role of UCH-L1 in modulating ERα status and demonstrate the involvement of UCH-L1-EGFR signaling pathway, suggesting that UCH-L1 may serve as a novel adjuvant target for treatment of hormone therapy-insensitive breast cancers. Targeting UCH-L1 to sensitize ER negative breast cancer to anti-estrogen therapy might represent a new therapeutic strategy that warrants further exploration.

Repeated failures of "Aβ-lowering" therapies call for new targets and therapeutic approaches for Alzheimer's disease (AD). We propose to treat AD by halting neuronal death and repairing synapses using a BDNF-based therapy. To overcome the poor druggability of BDNF, we have developed an agonistic antibody AS86 to mimic the function of BDNF, and evaluate its therapeutic potential for AD. Method: Biochemical, electrophysiological and behavioral techniques were used to investigate the effects of AS86 in vitro and in vivo. Results: AS86 specifically activated the BDNF receptor TrkB and its downstream signaling, without affecting its other receptor p75NTR. It promoted neurite outgrowth, enhanced spine growth and prevented Aβ-induced cell death in cultured neurons, and facilitated Long-Term Potentiation (LTP) in hippocampal slices. A single-dose tail-vein injection of AS86 activated TrkB signaling in the brain, with a half-life of 6 days in the blood and brain. Bi-weekly peripheral administration of AS86 rescued the deficits in object-recognition memory in the APP/PS1 mouse model. AS86 also reversed spatial memory deficits in the 11-month, but not 14-month old AD mouse model. Conclusion: These results demonstrate the potential of AS86 in AD therapy, suggesting that neuronal and/or synaptic repair as an alternative therapeutic strategy for AD.

Rationale: Accumulating evidence shows that Rho-GTPase-activating proteins (RhoGAPs) exert suppressive roles in cancer cell proliferation and metastasis. However, no study has systematically investigated the clinical significance of RhoGAPs and analyzed the functions of ARHGAP24 in hepatocellular carcinoma (HCC). Methods: The relationship between RhoGAP expression and HCC prognosis was investigated via using The Cancer Genome Atlas and Gene Expression Omnibus databases. ARHGAP24 expression was detected by reverse transcription-polymerase chain reaction, western blot and immunohistochemistry staining assays. Moreover, in vitro assays including cell counting kit-8, colony formation, wound healing and Transwell assays, and in vivo tumor growth and pulmonary metastases evaluations were conducted to evaluate the biological function of ARHGAP24 in HCC. Liquid chromatography-tandem mass spectrometry, co-immunoprecipitation, GTPase activation, ubiquitination, and luciferase reporter assays and bioinformatics analysis were carried out to gain insights into the mechanisms underlying the tumor-suppressive function of ARHGAP24. Results: ARHGAP24 expression was dramatically decreased in HCC tissues, and low ARHGAP24 expression was an independent poor prognostic indicator for progression-free survival in HCC patients. ARHGAP24 overexpression significantly inhibited cell proliferation, migration and invasion, while knockdown of ARHGAP24 exerted the opposite effects. Through Gene Set Enrichment Analysis (GSEA), we found ARHGAP24 mainly suppressed HCC cell proliferation and invasion by attenuating β-catenin transactivation and blocking β-catenin signaling could effectively abolish the promotional effects of ARHGAP24 knockdown in HCC cells. Notably, GAP-deficient mutant of ARHGAP24 exerted similar inhibitory effects as the wild-type did, indicating suppressive function of ARHGAP24 was independent of its RhoGAP activity. Moreover, we identified pyruvate kinase M2 (PKM2) as a new binding partner of ARHGAP24, which recruited a novel E3 ligase (WWP1) and subsequently promoted PKM2 degradation. WWP1 knockdown significantly reduced the inhibitory function of ARHGAP24, and the C-terminal fragments of ARHGAP24 (amino acids 329 - 430 and 631 - 748) bound directly to WWP1 and PKM2 (amino acids 388 - 531), respectively. Conclusions: Our data indicate that ARHGAP24 may be an independent prognostic indicator for HCC. It is a critical suppressor of HCC that recruits WWP1 for PKM2 degradation. Targeting the ARHGAP24/WWP1/PKM2/β-catenin axis may provide new insights into HCC prevention and treatment.