AKT inhibitor Hu7691 induces differentiation of neuroblastoma cells

While neuroblastoma accounts for 15%of childhood tumor-related deaths,treatments against neuroblastoma remain scarce and mainly consist of cytotoxic chemotherapeutic drugs.Currently,maintenance therapy of differentiation induction is the standard of care for neuroblastoma patients in clinical,especially high-risk patients.However,differentiation therapy is not used as a first-line treatment for neuroblastoma due to low efficacy,unclear mechanism,and few drug options.Through compound library screening,we accidently found the potential differentiation-inducing effect of AKT inhibitor Hu7691.The protein kinase B(AKT)pathway is an important signaling pathway for regulating tumorigenesis and neural differentiation,yet the relation between the AKT pathway and neuroblastoma differentiation remains unclear.Here,we reveal the anti-proliferation and neurogenesis effect of Hu7691 on multiple neuroblastoma cell lines.Further evidence including neurites outgrowth,cell cycle arrest,and differentiation mRNA marker clarified the differentiation-inducing effect of Hu7691.Meanwhile,with the introduction of other AKT inhibitors,it is now clear that multiple AKT inhibitors can induce neuroblastoma differentiation.Furthermore,silencing AKT was found to have the effect of inducing neuroblastoma differentiation.Finally,confirmation of the therapeutic effects of Hu7691 is dependent on inducing differentiation in vivo,suggesting that Hu7691 is a potential molecule against neuroblastoma.Through this study,we not only define the key role of AKT in the progression of neuroblastoma differentiation but also provide potential drugs and key targets for the application of differentiation therapies for neuroblastoma clinically.

Upregulation of miR-489-3p and miR-630 inhibits oxaliplatin uptake in renal cell carcinoma by targeting OCT2

Renal cell carcinoma(RCC) is one of the most common malignant tumors affecting the urogenital system, accounting for 90% of renal malignancies. Traditional chemotherapy options are often the front-line choice of regimen in the treatment of patients with RCC, but responses may be modest or limited due to resistance of the tumor to anticarcinogen. Downregulated expression of organic cation transporter OCT2 is a possible mechanism underlying oxaliplatin resistance in RCC treatment. In this study, we observed that mi R-489-3 p and mi R-630 suppress OCT2 expression by directly binding to the OCT2 30-UTR. Meanwhile, via 786-O-OCT2-mi RNAs stable expression cell models, we found that mi RNAs could repress the classic substrate 1-methyl-4-phenylpyridinium(MPP+), fluorogenic substrate N,N-dimethyl-4-(2-pyridin-4-ylethenyl) aniline(ASP+), and oxaliplatin uptake by OCT2 both in vitro and in xenografts. In 33 clinical samples, mi R-489-3 p and mi R-630 were significantly upregulated in RCC, negatively correlating with the OCT2 expression level compared to that in adjacent normal tissues, using tissue microarray analysis and q PCR validation. The increased binding of c-Myc to the promoter of pri-mi R-630, responsible for the upregulation of mi R-630 in RCC, was further evidenced by chromatin immunoprecipitation and dual-luciferase reporter assay. Overall, this study indicated that mi R-489-3 p and mi R-630 function as oncotherapy-obstructing micro RNAs by directly targeting OCT2 in RCC.

ZDHHC12-mediated claudin-3 S-palmitoylation determines ovarian cancer progression

The membrane protein claudin-3(CLDN3) is critical for the formation and maintenance of tight junction and its high expression has been implicated in dictating malignant progression in various cancers. However, the post-translational modification of CLDN3 and its biological function remains poorly understood. Here, we report that CLDN3 is positively correlated with ovarian cancer progression both in vitro and in vivo. Of interest, CLDN3 undergoes S-palmitoylation on three juxtamembrane cysteine residues, which contribute to the accurate plasma membrane localization and protein stability of CLDN3. Moreover, the deprivation of S-palmitoylation in CLDN3 significantly abolishes its tumorigenic promotion effect in ovarian cancer cells. By utilizing the co-immunoprecipitation assay, we further identify ZDHHC12 as a CLDN3-targating palmitoyltransferase from 23 ZDHHC family proteins.Furthermore, the knockdown of ZDHHC12 also significantly inhibits CLDN3 accurate membrane localization, protein stability and ovarian cancer cells tumorigenesis. Thus, our work reveals S-palmitoylation as a novel regulatory mechanism that modulates CLDN3 function, which implies that targeting ZDHHC12-mediated CLDN3 S-palmitoylation might be a potential strategy for ovarian cancer therapy.

Targeting slug-mediated non-canonical activation of c-Met to overcome chemo-resistance in metastatic ovarian cancer cells

Metastasis-associated drug resistance accounts for high mortality in ovarian cancer and remains to be a major barrier for effective treatment. In this study, SKOV3/T4, a metastatic subpopulation of ovarian cancer SKOV3 cells, was enriched to explore potential interventions against metastaticassociated drug resistance. Quantitative genomic and functional analyses were performed and found that slug was significantly increased in the SKOV3/T4 subpopulation and contributed to the high resistance of SKOV3/T4. Further studies showed that slug activated c-Met in a ligand-independent manner due to elevated levels of fibronectin and provoked integrin α V function, which was confirmed by the significant correlation of slug and p-Met levels in 121 ovarian cancer patient samples. Intriguingly,c-Met inhibitor(s) exhibited greatly enhanced anti-cancer effects in slug-positive ovarian cancer models both in vitro and in vivo. Additionally, IHC analyses revealed that slug levels were highly correlated with reduced survival of ovarian cancer patients. Taken together, this study not only uncovers the critical roles of slug in drug resistance in ovarian cancer but also highlights a promising therapeutic strategy by targeting the noncanonical activation of c-Met in slug-positive ovarian cancer patients with poor prognosis.

Phosphorylation regulates cullin-based ubiquitination in tumorigenesis

Cullin-RING ligases(CRLs)recognize and interact with substrates for ubiquitination and degradation,and can be targeted for disease treatment when the abnormal expression of substrates involves pathologic processes.Phosphorylation,either of substrates or receptors of CRLs,can alter their interaction.Phosphorylation-dependent ubiquitination and proteasome degradation influence various cellular processes and can contribute to the occurrence of various diseases,most often tumorigenesis.These processes have the potential to be used for tumor intervention through the regulation of the activities of related kinases,along with the regulation of the stability of specific oncoproteins and tumor suppressors.This review describes the mechanisms and biological functions of crosstalk between phosphorylation and ubiquitination,and most importantly its influence on tumorigenesis,to provide new directions and strategies for tumor therapy.

Blockade of deubiquitinase YOD1 degrades oncogenic PML/RARα and eradicates acute promyelocytic leukemia cells

In most acute promyelocytic leukemia(APL)cells,promyelocytic leukemia(PML)fuses to retinoic acid receptor α (RARα)due to chromosomal translocation,thus generating PML/RARαoncoprotein,which is a relatively stable oncoprotein for degradation in APL.Elucidating the mechanism regulating the stability of PML/RARαmay help to degrade PML/RARαand eradicate APL cells.Here,we describe a deubiquitinase(DUB)-involved regulatory mechanism for the maintenance of PML/RARαstability and develop a novel pharmacological approach to degrading PML/RARαby inhibiting DUB.We utilized a DUB siRNA library to identify the ovarian tumor protease(OTU)family member deubiquitinase YOD1 as a critical DUB of PML/RARα.Suppression of YOD1 promoted the degradation of PML/RARα,thus inhibiting APL cells and prolonging the survival time of APL cell-bearing mice.Subsequent phenotypic screening of small molecules allowed us to identify ubiquitin isopeptidase inhibitor I(G5)as the first YOD1 pharmacological inhibitor.As expected,G5 notably degraded PML/RARαprotein and eradicated APL,particularly drug-resistant APL cells.Importantly,G5 also showed a strong killing effect on primary patient-derived APL blasts.Overall,our study not only reveals the DUB-involved regulatory mechanism on PML/RARαstability and validates YOD1 as a potential therapeutic target for APL,but also identifies G5 as a YOD1 inhibitor and a promising candidate for APL,particularly drug-resistant APL treatment.

WSB1 regulates c-Myc expression through β-catenin signaling and forms a feedforward circuit

The dysregulation of transcription factors is widely associated with tumorigenesis.As the most well-defined transcription factor in multiple types of cancer,c-Myc can transform cells by transactivating various downstream genes.Given that there is no effective way to directly inhibit c-Myc,c-Myc targeting strategies hold great potential for cancer therapy.In this study,we found that WSB1,which has a highly positive correlation with c-Myc in 10 cancer cell lines and clinical samples,is a direct target gene of c-Myc,and can positively regulate c-Myc expression,which forms a feedforward circuit promoting cancer development.RNA sequencing results from Bel-7402 cells confirmed that WSB1 promoted cMyc expression through theβ-catenin pathway.Mechanistically,WSB1 affectedβ-catenin destruction complex-PPP2CA assembly and E3 ubiquitin ligase adaptorβ-TRCP recruitment,which inhibited the ubiquitination ofβ-catenin and transactivated c-Myc.Of interest,the effect of WSB1 on c-Myc was independent of its E3 ligase activity.Moreover,overexpressing WSB1 in the Bel-7402 xenograft model could further strengthen the tumor-driven effect of c-Myc overexpression.Thus,our findings revealed a novel mechanism involved in tumorigenesis in which the WSB1/c-Myc feedforward circuit played an essential role,highlighting a potential c-Myc intervention strategy in cancer treatment.