snoRNAs: functions and mechanisms in biological processes, and roles in tumor pathophysiology.

Small nucleolar RNAs (snoRNAs), a type of non-coding RNA, are widely present in the nucleoli of eukaryotic cells and play an important role in rRNA modification. With the recent increase in research on snoRNAs, new evidence has emerged indicating that snoRNAs also participate in tRNA and mRNA modification. Studies suggest that numerous snoRNAs, including tumor-promoting and tumor-suppressing snoRNAs, are not only dysregulated in tumors but also show associations with clinical prognosis. In this review, we summarize the reported functions of snoRNAs and the possible mechanisms underlying their role in tumorigenesis and cancer development to guide the snoRNA-based clinical diagnosis and treatment of cancer in the future.

Insights into roles of METTL14 in tumors.

N6-Methyladenosine (m6A) is considered the most common and endogenous modification of eukaryotic RNAs. Highly conserved in many species, m6A regulates RNA metabolism, cell differentiation, cell circadian rhythm, and cell cycle; it also responds to endogenous and exogenous stimuli and is associated with the development of tumors. The m6A methyltransferase complex (MTC) regulates the m6A modification of transcripts and involves two components, methyltransferase-like enzyme 3 (METTL3) and methyltransferase-like enzyme 14 (METTL14), and other auxiliary regulatory distinct components. Though with no catalytic effect, METTL14 serves as an RNA-binding scaffold in MTC, promotes RNA substrate recognition, activates, and escalates the catalytic capability of METTL3, thus accounting for a pivotal member of the complex. It was reported that METTL14 regulates tumor proliferation, metastasis, and self-renewal, and plays a part in tumorigenesis, tumor progression, and other processes. The present work is a review of the role of METTL14 both as a tumor suppressor and a tumor promoter in the oncogenesis and progression of various tumors, as well as the potential molecular mechanisms.

CircCRIM1 promotes ovarian cancer progression by working as ceRNAs of CRIM1 and targeting miR-383-5p/ZEB2 axis.

BACKGROUND: Ovarian cancer is the leading cause of death in patients with gynecologic cancer, and circular RNAs (circRNAs) are involved in cancer progression. However, there are limited studies on the roles of circRNAs in ovarian cancer. METHODS: We designed divergent and convergent primers, used sanger sequencing and RNase R digestion to verify the source of circCRIM1. We detected the expression of circCRIM1 and its parental gene cysteine rich transmembrane BMP regulator 1 (CRIM1) in ovarian cancer and normal ovarian samples via qRT-PCR. MTT viability assay, apoptosis assay, wound healing assay and invasion assay were used to investigate the function of circCRIM1 and CRIM1 in ovarian cancer cell lines OVCAR3 and CAOV3. Mice xenografts experiment was performed. Bioinformatics predicted the microRNAs that bond with circCRIM1 and CRIM1, and dual luciferase reporter system confirmed it. Rescue experiments of microRNAs mimics transfection on the basis of circCRIM1 over-expression were carried out to uncover the mechanism by which circCRIM1 played cancer-promoting roles in ovarian cancer. RESULTS: CircCRIM1 was derived from CRIM1 by back-splicing. CircCRIM1 and CRIM1 had higher expression in ovarian cancer than in normal ovarian tissues, and both of them promoted ovarian cancer progression in vitro. In vivo circCRIM1 promoted the growth of tumors. CircCRIM1 and CRIM1 had a positive correlation relationship in the same cohort of ovarian cancer tissues. Bioinformatics predicted and dual luciferase assay confirmed circCRIM1 and CRIM1 bond with miR-145-5p, and circCRIM1 bond with miR-383-5p additionally. CircCRIM1 positively affected the expression of CRIM1. After circCRIM1 was over-expressed, miR-145-5p mimics transfection reversed the expression of CRIM1. Western blot discovered circCRIM1 positively affected the expression of zinc finger E-box binding homeobox 2 (ZEB2). Rescue experiments found miR-383-5p mimics reversed ZEB2 expression and the cancer-promoting effects of circCRIM1. CONCLUSIONS: CircCRIM1 bond with miR-145-5p to work as competing endogenous RNA (ceRNA) of CRIM1, and circCRIM1 bond with miR-383-5p to improve the expression of ZEB2 in ovarian cancer. CircCRIM1 and CRIM1 promoted the ovarian cancer progression and supplied a novel insight into the researches of ovarian cancer.

[Clinical analysis of the vascular pulsatile tinnitus associated with sigmoid sinus-mastoid].

Objective:To probe the clinical characteristics of diagnosis and therapy of vascular pulsatile tinnitus（PT） associated with sigmoid sinus-mastoid. Methods:Retrospectively analyzed the clinical data of the hospitalized 45 PT patients of an ear surgeon in one hospital between January 2013 to January 2020, and observed the effectiveness with surgery and non-surgery therapy. Surgical procedures include reconstruction the bone wall of sigmoid sinus by transmastoid approach and ligation of mastoid emissary vein. Non-surgery therapy includes anti-anemia therapy and observation. All patients have been followed-up in ENT outpatient. Results: Of 45 cases, female：male was 43：2, the mean age was 42.7 years old. The other PT patients were the subjective tinnitus except two females were the objective tinnitus. Of 40 cases, 38 patients underwent transmastoid approach to reconstructed sigmoid sinus bone wall, including 6 patients with the ligated mastoid emissary vein at the same period.The other 2 cases with the ligated mastoid emissary vein only.Five cases were treated by non-surgery therapies, including 2 cases anti-anemia therapy and 3 cases observation. The longest follow-up period was seven and a half years, the shortest was six months. One case was lost to follow up. The total cure rate was 80.0%（36/45），the surgery cure rate was 82.5%（33/40）, the non-surgery cure rate was 60.0% （3/5）. Conclusion:The pathophysiologic mechanism of the PT is still complex and unclear until now. However, the following conditions probably play an important role in the etiology: female, common features of anatomy anomalies, hemodynamic variations. It is a key point to confirm the responsible site or the main cause of the PT . Although the surgery is relatively simple, the effect is remarkable and no major postoperative complications，surgery could not be a only choice.

circRNA circFAT1(e2) Elevates the Development of Non-Small-Cell Lung Cancer by Regulating miR-30e-5p and USP22.

BACKGROUND: As a newly discovered regulatory RNA, circular RNA (circRNA) has become a hot spot in many tumor pieces of research. In recent years, it has been discovered that circRNAs have multiple biological effects in different stages of cancer. However, the expression pattern and mechanism of circFAT1(e2) in non-small-cell lung cancer (NSCLC) are still unclear. METHODS: The expressions of circFAT1(e2) in NSCLC tissues and cell lines were studied. Functionally, CCK-8 and transwell experiments were performed in A549 and H1299. In addition, we also performed a dual-luciferase report analysis to clarify the mechanism of action of circFAT1(e2). RESULTS: circFAT1(e2) was significantly upregulated in NSCLC tissues and cell lines. circFAT1(e2) gene knockdown could significantly inhibit the proliferation, migration, and invasion of NSCLC cells. Loss of function testing found that circFAT1(e2) functioned as an oncogene in NSCLC cells. In addition, circFAT1(e2) acted as a ceRNA to spongy miR-30e-5p, which led to the increase in USP22 and promoted cell growth. CONCLUSIONS: The circFAT1(e2)-miR-30e-5p-USP22 axis is a crucial part of the progression of NSCLC. This study suggests that circFAT1(e2) may be an important potential of prognostic prediction and treatment targets for NSCLC patients.

Circ-NOLC1 promotes epithelial ovarian cancer tumorigenesis and progression by binding ESRP1 and modulating CDK1 and RhoA expression.

Circular RNAs (circRNAs) play important roles in cancer tumorigenesis and progression, representing prognostic biomarkers and therapeutic targets. In this case, we demonstrated the role of circ-NOLC1 in epithelial ovarian cancer (EOC). Our results have shown that Circ-NOLC1 expression was higher in EOC tissues than in normal tissues, and was positively associated with FIGO stage, differentiation. Among ovarian cancer cell lines, circ-NOLC1 expression was the highest in A2780, and lowest in CAOV3. Overexpression of circ-NOLC1 in CAOV3 cells increased cell proliferation, migration, and invasion ability, whereas silencing of circ-NOLC1 in A2780 cells had the opposite effect: however, neither circ-NOLC1 downregulation nor overexpression influenced NOLC1 mRNA expression. In nude mice with subcutaneous tumors, circ-NOLC1 downregulation decreased tumor growth. Bioinformatic analysis and RNA-binding protein immunoprecipitation showed that circ-NOLC1 could bind to ESRP1. In addition, the overexpression of circ-NOLC1 significantly increased ESRP1, RhoA, and CDK1 protein and mRNA expression level; circ-NOLC1 downregulation had the opposite effects. The tumor-promoting effect of circ-NOLC1 was inhibited by knockdown of ESRP1, CDK1, or RhoA expression in circ-NOLC1-overexpressing cells, which might act by modulating RhoA and CDK1 expression. In conclusion, our study demonstrated that Circ-NOLC1 might promote EOC tumorigenesis and development by binding ESRP1 and modulating CDK1 and RhoA expression.

Loss of ZIP facilitates JAK2-STAT3 activation in tamoxifen-resistant breast cancer.

Tamoxifen, a widely used modulator of the estrogen receptor (ER), targets ER-positive breast cancer preferentially. We used a powerful validation-based insertion mutagenesis method to find that expression of a dominant-negative, truncated form of the histone deacetylase ZIP led to resistance to tamoxifen. Consistently, increased expression of full-length ZIP gives the opposite phenotype, inhibiting the expression of genes whose products mediate resistance. An important example is JAK2 By binding to two specific sequences in the promoter, ZIP suppresses JAK2 expression. Increased expression and activation of JAK2 when ZIP is inhibited lead to increased STAT3 phosphorylation and increased resistance to tamoxifen, both in cell culture experiments and in a mouse xenograft model. Furthermore, data from human tumors are consistent with the conclusion that decreased expression of ZIP leads to resistance to tamoxifen in ER-positive breast cancer.

Discovery and evaluation of Atopaxar hydrobromide, a novel JAK1 and JAK2 inhibitor, selectively induces apoptosis of cancer cells with constitutively activated STAT3.

The Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway plays a vital role in immunity, cell division, cell death and tumor formation. Disrupted JAK-STAT signaling may lead to various diseases, especially cancer and immune disorders. Because of its importance, this signaling pathway has received significant attention from the pharmaceutical and biotechnology industries as a therapeutic target for drug design. However, few JAK or STATs inhibitors have been developed for cancer treatment. We used an in vitro STAT3 luciferase reporter assay to find novel inhibitors that could effectively block the JAK-STAT pathway. In our study, we screened 16,081 drug-like chemicals and found that atopaxar hydrobromide (AHB) is a specific inhibitor of JAK-STAT3 signaling. Our results suggest that AHB not only blocks constitutively activated and cytokine-induced STAT3 phosphorylation but also inhibits JAK1 and JAK2 phosphorylation. Moreover, AHB induces G1 phase cell cycle arrest, which stops cancer cell growth and induces apoptosis. AHB also inhibited tumor cell growth in vivo. In conclusion, AHB is a potential inhibitor that could be developed as a JAK-STAT pathway drug.

CircWHSC1 promotes ovarian cancer progression by regulating MUC1 and hTERT through sponging miR-145 and miR-1182.

BACKGROUND: Circular RNAs are key regulators in human cancers, however, there is a lack of studies on circRNAs' specific functions in ovarian cancer. METHODS: Our study used qRT-PCR to detect the differentially expressed circRNAs between normal ovaries and ovarian cancer tissues. Cell function experiments were performed to verify the role of overexpression and silence of circWHSC1, including MTT assay, cell apoptosis assay, wound healing and Matrigel-coated Transwell assay. In vivo tumorigenesis model was constructed by subcutaneous injection in nude mice. Bioinformatics analysis predicted the possible binding sites of circWHSC1 with miRNAs, and confirmed with dual-luciferase reporter assay and RNA pull-down assay. The exosomes were extracted with ultracentrifugation. HE staining was also used to detect morphology of nude mice peritoneum. RESULTS: We found that circWHSC1 was up-regulated in ovarian cancer tissues, and circWHSC1 expression was higher in moderate & poor differentiation ovarian cancer tissues than in well differentiation ovarian cancer tissues. Overexpression of circWHSC1 increased cell proliferation, migration and invasion, and inhibited cell apoptosis. Silence of circWHSC1 exerted the opposite effects. Additionally, circWHSC1 could sponge miR-145 and miR-1182 and up-regulate the expression of downstream targets MUC1 and hTERT. Exosomal circWHSC1 can be transferred to peritoneal mesothelial cells and promotes peritoneal dissemination. CONCLUSIONS: Our study demonstrates the highly expressed circWHSC1 in ovarian cancer promotes tumorigenesis by sponging miR-145 and miR-1182, and its exosome forms induce tumor metastasis through acting on peritoneal mesothelium.

TGF-ß2 antagonizes IL-6-promoted cell survival.

Transforming growth factor beta is a key cytokine involved in the pathogenesis of fibrosis in many organs, whereas interleukin-6 plays an important role in the regulation of inflammation. They are both potent angiogenesis inducers with opposite effects on cell survival and apoptosis. TGF-ß2 induces apoptosis; in contrast, IL-6 protects cells from apoptosis. The possible interaction between these two cytokines is indicated in various disease states. In this study, we have assessed the effect of TGF-ß2 on IL-6 signaling and found that TGF-ß2 could strongly inhibit IL-6-induced STAT3 activation and synergy with IL-6 resulting in enhanced SOCS3 expression. Interestingly, IL-6 also slows down the decay of TGF-ß2 mRNA. Consistent with this mechanism, we found that TGF-ß2 could antagonize IL-6 effect on cell survival in both γ-irradiation and UV light-induced apoptosis. Taken together, the finding shows that TGF-ß2 serves as a negative regulator of IL-6 signaling and antagonizes the anti-apoptosis effect of IL-6.

circ-CSPP1 promotes proliferation, invasion and migration of ovarian cancer cells by acting as a miR-1236-3p sponge.

Circular RNAs are known to participate in tumorigenesis through a variety of pathways, and as such, have potential to serve as molecular markers in tumor diagnosis and treatment. Here, using quantitative reverse transcription (qRT)-PCR, we showed that circ-CSPP1 is highly expressed in ovarian cancer (OC) tissues. Particularly, we detected circ-CSPP1 expression in three OC cell lines; of which, OVCAR3 and A2780 demonstrated higher levels of circ-CSPP1 expression, and CAOV3 showed lower circ-CSPP1 expression level. Subsequent silencing of circ-CSPP1 in OVCAR3 and A2780 cell lines revealed decreased cell growth, migration and invasion, while overexpression of circ-CSPP1 caused opposite results We also found that miR-1236-3p is a target of circ-CSPP1. Circ-CSPP1 silencing increased the expression of miR-1236-3p, and circ-CSPP1 overexpression decreased miR-1236-3p expression. MiR-1236-3p reportedly plays a tumor-suppressor role in OC by targeting zinc finger E-box binding homeobox 1 (ZEB1). In agreement with this, we showed that silencing circ-CSPP1 significantly decreased ZEB1 expression at both RNA and protein levels, and epithelial-mesenchymal transition (EMT) related markers (E-cadherin and N-cadherin) varied with ZEB1 expression. Circ-CSPP1 silencing also caused decreased expression of matrix metalloproteinase-2 (MMP-2) and vascular endothelial growth factor A (VEGFA), both of which are related to tumorigenesis. Overexpression of circ-CSPP1 had opposite effects. In addition, we indicated that the tumor-promoting effect was inhibited after we transfected miR-1236-3p into circ-CSPP1 overexpressing OC cells. Altogether, our findings suggest that by acting as a miR-1236-3p sponge, circ-CSPP1 impairs the inhibitory effect of miR-1236-3p on ZEB1, which subsequently promotes EMT and OC development.

E2F is required for STAT3-mediated upregulation of cyclin B1 and Cdc2 expressions and contributes to G2-M phase transition.

Activation of transcription factor STAT3 is involved in cell proliferation, differentiation, and cell survival. Constitutive activation of STAT3 pathway has been associated with the oncogenesis of various types of cancers. It has been reported that STAT3 plays a key role in the G1 to S phase cell cycle transition induced by the cytokine receptor subunit gp130, through the upregulation of cyclins D1, D2, D3, A, and Cdc25A and the concomitant downregulation of p21 and p27. However, its role in mediating G2-M phase transition has not been studied. The cyclin B1/Cdc2 complex is widely accepted as the trigger of mitosis in all organisms and is believed to be necessary for progression through S phase and keep active during the G2-M transition and progression. In the present study, we found that activation of STAT3 stimulates cyclin B1 and Cdc2 expressions. Deletion and site-directed mutations on cyclin B1 and Cdc2 promoters indicated that E2F element mediates the upregulation of these two promoters in a STAT3-dependent manner. The findings reported here demonstrated that STAT3 participates in modulating G2-M phase checkpoint by regulating gene expressions of cyclin B1 and Cdc2 via E2F.

lncRNA DLEU1 contributes to tumorigenesis and development of endometrial carcinoma by targeting mTOR.

lncRNA DLEU1 as a non-coding gene, involves in the occurrence and development of multiple tumors. However, there is no related report in endometrial carcinoma. In order to focus on the role and mechanism of lncRNA DLEU1 in endometrial carcinoma, we used qRT-PCR to detect the expression of lncRNA DLEU1 and found that lncRNA DLEU1 was highly expressed in endometrial carcinoma compared to normal endometrium. Moreover, compared to Ishikawa and KLE, lncRNA DLEU1 was higher in HEC-1B. In addition, up-regulation of lncRNA DLEU1 promoted cell viability, migration, invasion, and reduced the proportion of apoptosis. Otherwise, down-regulation of lncRNA DLEU1 produced opposite results. Xenograft nude mice model assay showed that lncRNA DLEU1 can promote tumorigenesis in vivo. RiP confirmed that lncRNA DLEU1 could bind to mTOR. The rescue experiments revealed that silence of mTOR after up-regulation of lncRNA DLEU1 resulted in decrease of cell viability, migration, and invasion and increase of apoptosis. The expression changes of PI3K, AKT1, p70S6K, rpS6, GSK3ß, STAT3, and Bcl-xl were consistent with lncRNA DLEU1 and mTOR in Western blot. Thus, we suggest that lncRNA DLEU1 combines with mTOR and then increases the expression of PI3K/AKT/mTOR pathway to promote endometrial carcinoma tumorigenesis and progression. The present discovery has probability to provide a biomarker and lay the foundation for targeted therapy of endometrial carcinoma.

Inhibition of breast cancer cell survival by Xanthohumol via modulation of the Notch signaling pathway in vivo and in vitro.

Natural compounds derived from plants have been an important source of numerous clinically useful anticancer agents. Nevertheless, limited studies indicate that xanthohumol (XN), a major prenylated flavonoid in hop plants (Humulus lupulus), may possess anticarcinogenic properties. The purpose of the present study was to clarify the antitumorigenic effects and the underlying mechanism of XN on breast cancer in vivo and in vitro. A 4T1 breast tumor mouse model was used in the present study to investigate XN suppression of tumor growth as detected by tumorigenicity assays in vivo. In addition, in vitro studies revealed that XN significantly decreased cell viability, induced G0/G1 cell cycle arrest and apoptosis in MCF-7 and MDA-MB-231 cells, as confirmed by an MTT assay, flow cytometry and western blot analysis, indicating anticarcinogenic activity of XN against breast cancer. Furthermore, immunohistochemistry was performed to confirm the inactivation of the Notch signaling pathway, Notch 1 and Ki-67, in vivo; consistently, XN caused decreased activation of the Notch signaling pathway and apoptotic regulators B-cell lymphoma-2 (Bcl-2), Bcl-extra large and caspase 3, as determined by western blot analysis in vitro. This study suggests that XN may potentially be useful as a chemopreventive agent during breast hyperplasia and carcinogenesis, acting via the regulation of Notch associated apoptotic regulators in vivo and in vitro.

Astragaloside IV attenuates penicillin-induced epilepsy via inhibiting activation of the MAPK signaling pathway.

Astrocytes perform several functions in the brain and spinal cord. Penicillin is commonly used for establishment of experimental epilepsy models. Previous studies have demonstrated that astragaloside IV (3-o-ß-d-xylopyranosyl-6-o-ß-d-glucopyranosyl-cycloastragenol; AS­IV) has comprehensive pharmacological functions on the attenuation of inflammation. In the present study, primary astrocyte cell cultures were divided into three groups: Control group, penicillin (2,500 µM) treatment group (epilepsy model), and penicillin+AS­IV (20, 40, 80 and 160 µmol/l) treatment group. The expression levels of inflammatory factors, including interleukin­1ß and tumor necrosis factor­α, were determined in the groups using western blot and reverse transcription­quantitative polymerase chain reaction analyses. The levels of members of the phosphorylated­mitogen­activated protein kinase (p­MAPK) family, including p­c­Jun N­terminal kinase 1/2, p­extracellular signal­regulated protein kinase 1/2 and p­p38, were determined using western blot analysis. Cell viability of the astrocytes was detected using a 3­(4,5­dimethyl­2­thiazolyl)­2,5­diphenyl­2­H­tetrazolium bromide assay and cell proliferation was evaluated using a Cell Counting Kit­8 assay. The results revealed that AS­IV significantly suppressed the expression of penicillin­induced inflammatory factors in the astrocytes at the transcriptional and translational levels, and occurred in a dose­dependent manner. The penicillin­induced increase in the protein levels of the the p­MAPK family were notably decreased by AS­IV. In addition, the penicillin­induced downregulation of primary astrocyte viability/cell proliferation was significantly reversed by the administration of AS­IV. From these results, it was concluded that AS­IV suppressed the penicillin­induced upregulation of inflammatory factors and p­MAPK in astrocytes, ultimately attenuating epilepsy.

Effect of xanthohumol on Th1/Th2 balance in a breast cancer mouse model.

Xanthohumol (XN), a prenylflavonoid found in the hop plant, Humulus lupulus, exhibits a variety of biological activities. Numerous studies have reported that XN inhibits the growth of many types of cancer cells, but the effects of XN on tumor immunity have not yet been studied. We explored the effect of XN on Th1/Th2 balance and the underlying mechanism based on a BALB/c-4T1 breast cancer mouse model. The results showed that XN significantly slowed down tumor growth and inhibited expression of antitumor proliferation protein Ki-67 as well as breast cancer-specific marker cancer antigen 15-3 (CA15-3). Flow cytometric analysis revealed that XN enhanced the secretion of perforin, granzyme B and increased the ratio of CD8+/CD25+. ELISA analysis of cytokine results demonstrated that XN obviously upregulated Th1 cytokines, while downregulated Th2 cytokines. Th1/Th2 ratio analysis by flow cytometry illustrated that XN regulated the balance drift to Th1 polarization. Western blotting and immunohistochemistry (IHC) results manifested that XN induced expression of T-bet, a Th1-specific transcription factor. Furthermore, we found that XN significantly promoted the phosphorylation of signal transducer and activator of transcription (STAT)4. Our results demonstrated that XN promoted Th1/Th2 balance towards Th1 polarization, and STAT4 may play a positive role in the regulation of Th1/Th2 cytokines by XN.

ZIP restores estrogen receptor expression and response to Tamoxifen in estrogen receptor negative tumors.

As a component of NURD histone deacetylase complex, ZIP serves as a tumor suppressor gene in the development of breast tumors. However, whether it takes part in chemotherapy resistance remains poorly defined. In the present study, we reported that ZIP enhanced the response to SERM chemotherapy in ER-negative cells. Overexpression of ZIP suppressed EGFR expression level and restored ERalpha protein level in cells resistant to Tamoxifen. In vivo data confirmed those in vitro findings.

Dehydrocrenatidine is a novel janus kinase inhibitor.

Janus kinase (JAK) 2 plays a pivotal role in the tumorigenesis of signal transducers and activators of transcription (STAT) 3 constitutively activated solid tumors. JAK2 mutations are involved in the pathogenesis of various types of hematopoietic disorders, such as myeloproliferative disorders, polycythemia vera, essential thrombocythemia, and primary myelofibrosis. Thus, small-molecular inhibitors targeting JAK2 are potent for therapy of these diseases. In this study, we screened 1,062,608 drug-like molecules from the ZINC database and 2080 natural product chemicals. We identified a novel JAK family kinase inhibitor, dehydrocrenatidine, that inhibits JAK-STAT3-dependent DU145 and MDA-MB-468 cell survival and induces cell apoptosis. Dehydrocrenatidine represses constitutively activated JAK2 and STAT3, as well as interleukin-6-, interferon-α-, and interferon-γ-stimulated JAK activity, and STAT phosphorylation, and suppresses STAT3 and STAT1 downstream gene expression. Dehydrocrenatidine inhibits JAKs-JH1 domain overexpression-induced STAT3 and STAT1 phosphorylation. In addition, dehydrocrenatidine inhibits JAK2-JH1 kinase activity in vitro. Importantly, dehydrocrenatidine does not show significant effect on Src overexpression and epidermal growth factor-induced STAT3 activation. Our results indicate that dehydrocrenatidine is a JAK-specific inhibitor.

N6-substituted adenosine analogues, a novel class of JAK2 inhibitors, potently block STAT3 signaling in human cancer cells.

The JAK2/STAT3 signaling pathway plays a critical role in oncogenesis and malignancy, which makes it a promising anticancer target. We report four N(6)-substituted adenosine analogues (AAs) as potential JAK2/STAT3 inhibitors identified through a STAT3-based high-throughput drug screening system. These AAs exhibited selective anti-cancer activity on human cancer cells and xenograft tumors with constitutively activated STAT3. They rapidly and potently suppressed constitutive and IL-6/IFN-γ-induced JAK2/STAT3 signal activation. In addition, we finally proved that the STAT3 signal blockage by three of these AAs was dependent on specific JAK2 inhibition. These AAs may represent new targeted therapeutic agents for JAK2/STAT3 hyper-activated human cancers.

Activation of Akt protects cancer cells from growth inhibition induced by PKM2 knockdown.

BACKGROUND: PKM2 is an attractive target for cancer therapy, however, for many cancer cells, PKM2 knockdown only leads to a modest impairment of survival and proliferation. It is not known whether PKM2 knockdown rewires cell signaling pathways in these "PKM2 knockdown resistant" cells, and whether the rewired pathways are needed for their survival. FINDINGS: In present study, we investigated the effects of PKM2 knockdown on cellular signaling pathways in "PKM2 knockdown resistant" cancer cells. We found that knockdown of PKM2 leads to activation of Akt. Furthermore, we revealed that activation of Akt in PKM2 knockdown cells is a result of glycolysis disruption. Inhibiton of PI3K-Akt signaling pathway leads to significant growth inhibition and apoptosis in PKM2 knockdown cells. CONCLUSIONS: Overall, our results indicate that activation of Akt is necessary for the survival of PKM2 knockdown cells. Combing PKM2 knockdown with PI3K or Akt inhibitors may lead to a better chance to kill tumors. Our research may provide an unexpected opportunity for the development and implementation of drugs targeting cell metabolism and aberrant Akt signaling.