Phosphorylation of PPDPF via IL6-JAK2 activates the Wnt/ß-catenin pathway in colorectal cancer.

Inflammation plays an important role in the initiation and progression of colorectal cancer (CRC) and leads to ß-catenin accumulation in colitis-related CRC. However, the mechanism remains largely unknown. Here, pancreatic progenitor cell differentiation and proliferation factor (PPDPF) is found to be upregulated in CRC and significantly correlated with tumor-node-metastasis (TNM) stages and survival time. Knockout of PPDPF in the intestinal epithelium shortens crypts, decreases the number of stem cells, and inhibits the growth of organoids and the occurrence of azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced CRC. Mechanistically, PPDPF is found to interact with Casein kinase 1α (CK1α), thereby disrupting its binding to Axin, disassociating the ß-catenin destruction complex, decreasing the phosphorylation of ß-catenin, and activating the Wnt/ß-catenin pathway. Furthermore, interleukin 6 (IL6)/Janus kinase 2 (JAK2)-mediated inflammatory signals lead to phosphorylation of PPDPF at Tyr16 and Tyr17, stabilizing the protein. In summary, this study demonstrates that PPDPF is a key molecule in CRC carcinogenesis and progression that connects inflammatory signals to the Wnt/ß-catenin signaling pathway, providing a potential novel therapeutic target.

Combinational delivery of TLR4 and TLR7/8 agonist enhanced the therapeutic efficacy of immune checkpoint inhibitors to colon tumor.

Immunotherapy is regarded as a potent cancer treatment, with DC vaccines playing a crucial role. Although clinical trials have demonstrated the safety and efficacy of DC vaccines, loading antigens in vitro is challenging, and their therapeutic effects remain unpredictable. Moreover, the diverse subtypes and maturity states of DCs in the body could induce both immune responses and immune tolerance, potentially affecting the vaccine's efficacy. Hence, the optimization of DC vaccines remains imperative. Our study discovered a new therapeutic strategy by using CT26 and MC38 mouse colon cancer models, as well as LLC mouse lung cancer models. The strategy involved the synergistic activation of DCs through intertumoral administration of TLR4 agonist high-mobility group nucleosome binding protein 1 (HMGN1) and TLR7/8 agonist (R848/resiquimod), combined with intraperitoneal administration of TNFR2 immunosuppressant antibody. The experimental results indicated that the combined use of HMGN1, R848, and α-TNFR2 had no effect on LLC cold tumors. However, it was effective in eradicating CT26 and MC38 colon cancer and inducing long-term immune memory. The combination of these three drugs altered the TME and promoted an increase in anti-tumor immune components. This may provide a promising new treatment strategy for colon cancer.

Recruitment of phosphatase PP2A by RACK1 adaptor protein deactivates transcription factor IRF3 and limits type I interferon signaling.

The transcription factor IRF3 is a central regulator of type I interferon (IFN) signaling. The mechanisms underlying deactivation of IRF3 are poorly understood although many studies suggest that IRF3 activity is terminated through degradation after viral infection. Here we report that IRF3 is deactivated via dephosphorylation mediated by the serine and threonine phosphatase PP2A and its adaptor protein RACK1. The PP2A-RACK1 complex negatively regulated the IRF3 pathway after LPS or poly(I:C) stimulation or Sendai virus (SeV) infection. After challenge with LPS, poly(I:C), or low-titer SeV, activated IRF3 was dephosphorylated and returned to resting state without being degraded, although high-titer SeV infection triggered the degradation of IRF3. Furthermore, PP2A-deficient macrophages showed enhanced type I IFN signaling upon LPS, poly(I:C), and SeV challenge and protected mice from lethal vesicular stomatitis virus infection. Therefore, dephosphorylation of IRF3 is a deactivation mechanism that contributes to termination of IRF3-type I IFN signaling.

DIAPH3 promotes pancreatic cancer progression by activating selenoprotein TrxR1-mediated antioxidant effects.

Pancreatic cancer is a highly malignant tumour of the digestive tract which is difficult to diagnose and treat. Approximately 90% of cases arise from ductal adenocarcinoma of the glandular epithelium. The morbidity and mortality of the disease have increased significantly in recent years. Its 5-year survival rate is <1% and has one of the worst prognoses amongst malignant tumours. Pancreatic cancer has a low rate of early-stage diagnosis, high surgical mortality and low cure rate. Selenium compounds produced by selenoamino acid metabolism may promote a large amount of oxidative stress and subsequent unfolded reactions and endoplasmic reticulum stress by consuming the NADPH in cells, and eventually lead to apoptosis, necrosis or necrotic cell death. In this study, we first identified DIAPH3 as a highly expressed protein in the tissues of patients with pancreatic cancer, and confirmed that DIAPH3 promoted the proliferation, anchorage-independent growth and invasion of pancreatic cancer cells using overexpression and interference experiments. Secondly, bioinformatics data mining showed that the potential proteins interacted with DIAPH3 were involved in selenoamino acid metabolism regulation. Selenium may be incorporated into selenoprotein synthesis such as TrxR1 and GPX4, which direct reduction of hydroperoxides or resist ferroptosis, respectively. Our following validation confirmed that DIAPH3 promoted selenium content and interacted with the selenoprotein RPL6, a ribosome protein subunit involved in selenoamino acid metabolism. In addition, we verified that DIAPH3 could down-regulate cellular ROS level via up-regulating TrxR1 expression. Finally, nude mice xenograft model experimental results demonstrate DIAPH3 knock down could decrease tumour growth and TrxR1 expression and ROS levels in vivo. Collectively, our observations indicate DIAPH3 could promote pancreatic cancer progression by activating selenoprotein TrxR1-mediated antioxidant effects.

Chemerin suppresses hepatocellular carcinoma metastasis through CMKLR1-PTEN-Akt axis.

BACKGROUND: Chemerin, a known chemoattractant, participates in multiple biological events. However, its role in cancer remains largely unknown. METHODS: Chemerin expression was evaluated by real-time PCR, western blot and immunohistochemistry. Forced expression, RNAi, immunoprecipitation, etc. were used in function and mechanism study. Mouse models of extrahepatic and intrahepatic metastasis were employed to evaluate the therapeutic potential of chemerin. RESULTS: Chemerin expression was significantly downregulated in hepatocellular carcinoma, and associated with poor prognosis of HCC patients. Forced expression of chemerin inhibited in vitro migration, invasion and in vivo metastasis of HCC cells. Administration of chemerin effectively suppressed extrahepatic and intrahepatic metastases of HCC cells, resulting in prolonged survival of tumour-bearing nude mice. Chemerin upregulated expression and phosphatase activity of PTEN by interfering with PTEN-CMKLR1 interaction, leading to weakened ubiquitination of PTEN and decreased p-Akt (Ser473) level, which was responsible for suppressed migration, invasion and metastasis of HCC cells. Positive correlation between chemerin and PTEN, and reverse correlation between chemerin and p-Akt (Ser473) were also observed in HCC clinical samples and intrahepatic mouse model in vivo. CONCLUSIONS: Our study has revealed the suppressive role and therapeutic potential of chemerin in HCC metastasis, providing both a prognostic marker and drug candidate for HCC.

PRMT1 Promoted HCC Growth and Metastasis In Vitro and In Vivo via Activating the STAT3 Signalling Pathway.

BACKGROUND/AIMS: Although it has been widely accepted that protein arginine methyltransferase 1 (PRMT1) is a cancer-promoting gene in various cancers, the mechanism of PRMT1 in hepatocellular carcinoma (HCC) requires more exploration. This study aimed to investigate the role of PRMT1 in HCC growth and metastasis. METHODS: We compared PRMT1 expression and clinicopathological characteristics using paired HCC and adjacent noncancerous liver tissues from 210 patients and immunohistochemistry analyses. Cell proliferation, colony formation and migration were determined in HCC cell lines with PRMT1 overexpression or downregulation through MTT, crystal violet and Boyden chamber assays. Tumour growth was monitored in a xenograft model, and intrahepatic metastasis models were established. RESULTS: PRMT1 expression was greatly increased in clinical HCC samples and strongly associated with poor prognosis and recurrence; PRMT1 expression was also positively correlated with microvascular invasion (P = 0.024), tumour differentiation (P = 0.014), tumour size (P = 0.002), and portal vein tumour thrombus (PVTT) (P = 0.028). Cell proliferation, colony formation and migration in vitro were enhanced by PRMT1 upregulation and decreased by PRMT1 downregulation in HCC cell lines. Moreover, low PRMT1 expression resulted in slow tumour growth and decreased tumour weight in vivo, as well as tumour metastasis. These phenotypes were associated with STAT3 signalling pathway activation. Cryptotanshinone, a STAT3 inhibitor, inhibited STAT3 phosphorylation and reversed the HCC phenotype of PRMT1 expression. CONCLUSIONS: We revealed a significant role for PRMT1 in HCC progression and metastasis in vitro and in vivo via STAT3 signalling pathway activation. PRMT1 may be a potential novel prognostic biomarker and new therapeutic target for HCC.

SF3B4 is decreased in pancreatic cancer and inhibits the growth and migration of cancer cells.

Splicing factor 3b subunit 4, a critical component of pre-message RNA splicing complex, has been reported to play an important part in the tumorigenesis. However, the expression pattern and biological role of splicing factor 3b subunit 4 in pancreatic cancer have never been investigated. In this study, we found that both the messenger RNA ( p < 0.001) and protein level of splicing factor 3b subunit 4 were decreased significantly in pancreatic cancer specimens compared with their adjacent normal tissues. Overexpression of splicing factor 3b subunit 4 in pancreatic cancer cells inhibited cell growth and motility in vitro, while suppressing splicing factor 3b subunit 4 expression promoted the proliferation and migration of pancreatic cancer cells. In addition, splicing factor 3b subunit 4 was found to inhibit the activity of signal transducer and activator of transcription 3 signaling via downregulating the phosphorylation of signal transducer and activator of transcription 3 on a tyrosine residue at position 705. Taken together, these findings demonstrated that splicing factor 3b subunit 4 acted as a suppressive role in pancreatic cancer and indicated that restoring the function of splicing factor 3b subunit 4 might be a strategy for cancer therapy.

Iron overload in hereditary tyrosinemia type 1 induces liver injury through the Sp1/Tfr2/hepcidin axis.

BACKGROUND & AIMS: Iron is an essential metal for fundamental metabolic processes, but little is known regarding the involvement of iron in other nutritional disorders. In the present study, we investigated disordered iron metabolism in a murine model of hereditary tyrosinemia type I (HT1), a disease of the tyrosine degradation pathway. METHODS: We analysed the status of iron accumulation following NTBC withdrawal from Fah(-/-) mice, a murine model for HT1. Liver histology and serum parameters were used to assess the extent of liver injury and iron deposition. To determine the physiological significance of iron accumulation, mice were subjected to a low-iron food intake to reduce the iron accumulation. Mechanistic studies were performed on tissues and cells using immunoblotting, qRT-PCR, adenovirus transfection and other assays. RESULTS: Severe iron overload was observed in the murine model of HT1 with dramatically elevated hepatic and serum iron levels. Mechanistic studies revealed that downregulation and dysfunction of Tfr2 decreased hepcidin, leading to iron overload. The Fah(-/-) hepatocytes lost the ability of transferrin-sensitive induction of hepcidin. Forced expression of Tfr2 in the murine liver reduced the iron accumulation. Moreover, transcription factor Sp1 was downregulated and identified as a new regulator of Tfr2 here. Additionally, low-iron food intake effectively reduced the iron deposits, protected the liver and prolonged the survival in these mice. CONCLUSIONS: Iron was severely overloaded in the HT1 mice via the Sp1/Tfr2/Hepcidin axis. The iron overload induced liver injury in the HT1 mice, and reduction of the iron accumulation ameliorated liver injury. LAY SUMMARY: Primary and secondary iron overload is an abnormal status affecting millions of people worldwide. Here, we reported severe iron overload in a murine model of HT1, a disease of the tyrosine degradation pathway, and elucidated the mechanistic basis and the physiological significance of iron overload in HT1. These studies are of general interest not only with respect to secondary iron-induced liver injury in HT1 but also are important to elucidate the crosstalk between the two metabolic pathways.

Sorafenib enriches epithelial cell adhesion molecule-positive tumor initiating cells and exacerbates a subtype of hepatocellular carcinoma through TSC2-AKT cascade.

UNLABELLED: Sorafenib is a specific adenosine triphosphate-competitive RAF inhibitor used as a first-line treatment of advanced hepatocellular carcinoma (HCC). However, the responses are variable, reflecting heterogeneity of the disease, while the resistance mechanism remains poorly understood. Here, we report that sorafenib treatment can exacerbate disease progression in both patient-derived xenografts and cell line-derived xenografts and that the therapeutic effect of the drug inversely covaries to the ratio of epithelial cell adhesion molecule-positive cells, which may be tumor initiating cells in HCC. The TSC2-AKT cascade mediates this sorafenib resistance. In response to sorafenib treatment, formation of the TSC1/2 complex is enhanced, causing increased phosphorylation of AKT, which contributes to up-regulation of "stemness"-related genes in epithelial cell adhesion molecule-positive cells and enhancement of tumorigenicity. The expression of TSC2 negatively correlated with prognosis in clinical sorafenib therapy. Furthermore, all-trans retinoic acid decreased AKT activity, reduced the epithelial cell adhesion molecule-positive cell population enriched by sorafenib, and potentiated the therapeutic effect of sorafenib in the patient-derived xenograft model. CONCLUSION: Our findings suggest that a subtype of HCC is not suitable for sorafenib therapy; this resistance to sorafenib can be predicted by the status of TSC2, and agents inducing differentiation of tumor initiating cells (e.g., all-trans retinoic acid) should improve the prognosis of this subtype of HCC.

Tyrosine hydroxylase inhibits HCC progression by downregulating TGFß/Smad signaling.

The alteration of metabolic processes has been found to have significant impacts on the development of hepatocellular carcinoma (HCC). Nevertheless, the effects of dysfunction of tyrosine metabolism on the development of HCC remains to be discovered. This research demonstrated that tyrosine hydroxylase (TH), which responsible for the initial and limiting step in the bio-generation of the neuro-transmitters dopamine and adrenaline, et al. was shown to be reduced in HCC. Increased expression of TH was found facilitates the survival of HCC patients. In addition, decreased TH indicated larger tumor size, much more numbers of tumor, higher level of AFP, and the presence of cirrhosis. TH effectively impairs the growth and metastasis of HCC cells, a process dependent on the phosphorylation of serine residues (S19/S40). TH directly binds to Smad2 and hinders the cascade activation of TGFß/Smad signaling with the treatment of TGFß1. In summary, our study uncovered the non-metabolic functions of TH in the development of HCC and proposes that TH might be a promising biomarker for diagnosis as well as an innovative target for metastatic HCC.

RACK1 promotes non-small-cell lung cancer tumorigenicity through activating sonic hedgehog signaling pathway.

Non-small-cell lung cancer (NSCLC) is a deadly disease due to lack of effective diagnosis biomarker and therapeutic target. Much effort has been made in defining gene defects in NSCLC, but its full molecular pathogenesis remains unexplored. Here, we found RACK1 (receptor of activated kinase 1) was elevated in most NSCLC, and its expression level correlated with key pathological characteristics including tumor differentiation, stage, and metastasis. In addition, RACK1 activated sonic hedgehog signaling pathway by interacting with and activating Smoothened to mediate Gli1-dependent transcription in NSCLC cells. And silencing RACK1 dramatically inhibited in vivo tumor growth and metastasis by blocking the sonic hedgehog signaling pathway. These results suggest that RACK1 represents a new promising diagnosis biomarker and therapeutic target for NSCLC.

RACK1 suppresses gastric tumorigenesis by stabilizing the ß-catenin destruction complex.

BACKGROUND & AIMS: Dysregulation of Wnt signaling has been involved in gastric tumorigenesis by mechanisms that are not fully understood. The receptor for activated protein kinase C (RACK1, GNB2L1) is involved in development of different tumor types, but its expression and function have not been investigated in gastric tumors. METHODS: We analyzed expression of RACK1 in gastric tumor samples and their matched normal tissues from 116 patients using immunohistochemistry. Effects of knockdown with small interfering RNAs or overexpression of RACK1 in gastric cancer cell lines were evaluated in cell growth and tumor xenograft. RACK1 signaling pathways were investigated in cells and zebrafish embryos using immunoblot, immunoprecipitation, microinjection, and in situ hybridization assays. RESULTS: Expression of RACK1 was reduced in gastric tumor samples and correlated with depth of tumor infiltration and poor differentiation. Knockdown of RACK1 in gastric cancer cells accelerated their anchorage-independent proliferation in soft agar, whereas overexpression of RACK1 reduced their tumorigenicity in nude mice. RACK1 formed a complex with glycogen synthase kinase Gsk3ß and Axin to promote the interaction between Gsk3ß and ß-catenin and thereby stabilized the ß-catenin destruction complex. On stimulation of Wnt3a, RACK1 repressed Wnt signaling by inhibiting recruitment of Axin by Dishevelled 2 (Dvl2). Moreover, there was an inverse correlation between expression of RACK1 and localization of ß-catenin to the cytoplasm/nucleus in human gastric tumor samples. CONCLUSIONS: RACK1 negatively regulates Wnt signaling pathway by stabilizing the ß-catenin destruction complex and act as a tumor suppressor in gastric cancer cells.

Phosphorylation by IKKß Promotes the Degradation of HMGCL via NEDD4 in Lung Cancer.

Inflammation and metabolic reprogramming are hallmarks of cancer. How inflammation regulates cancer metabolism remains poorly understood. In this study, we found that 3-hydroxy-3-methylglutaryl-CoA lyase (HMGCL), the enzyme that catalyzes the catabolism of leucine and promotes the synthesis of ketone bodies, was downregulated in lung cancer. Downregulation of HMGCL was associated with a larger tumor size and a shorter overall survival time. In a functional study, overexpression of HMGCL increased the content of ß-hydroxybutyrate (ß-HB) and inhibited the tumorigenicity of lung cancer cells, and deletion of HMGCL promoted de novo tumorigenesis in KP (KrasG12D;P53f/f) mice. Mechanistically, tumor necrosis factor α (TNFα) treatment decreased the HMGCL protein level, and IKKß interacted with HMGCL and phosphorylated it at Ser258, which destabilized HMGCL. Moreover, NEDD4 was identified as the E3 ligase for HMGCL and promoted its degradation. In addition, mutation of Ser258 to alanine inhibited the ubiquitination of HMGCL by NEDD4 and thus inhibited the anchorage-independent growth of lung cancer cells more efficiently than did wild-type HMGCL. In summary, this study demonstrated a link between TNFα-mediated inflammation and cancer metabolism.

Nicotinamide adenine dinucleotide kinase promotes lymph node metastasis of NSCLC via activating ID1 expression through BMP pathway.

Metastasis is a significant cause of high mortality in lung cancer. Lymph node (LN) metastasis is the most common metastatic pathway in non-small cell lung cancer and the most crucial factor affecting the prognosis of NSCLC. Nevertheless, the molecular mechanism underlying metastasis is unknown. We demonstrated that higher NADK expression suggests worsened survival prognosis, and NADK expression positively correlates with the lymph node metastasis rate and TNM and AJCC stages in NSCLC patients. Moreover, patients with LN metastasis show higher NADK expression than those without LN metastasis. NADK can promote NSCLC progression by enhancing the migration, invasion, lymph node metastasis and growth of NSCLC cells. Mechanistically, NADK inhibits the ubiquitination and degradation of BMPR1A by interacting with Smurf1, further activating the BMPs signalling pathway and promoting ID1 transcription. In conclusion, NADK may be a potential diagnostic indicator and a novel therapeutic target for metastatic NSCLC.

Sorafenib suppresses postsurgical recurrence and metastasis of hepatocellular carcinoma in an orthotopic mouse model.

UNLABELLED: Surgical resection is the first-line treatment for hepatocellular carcinoma (HCC) patients with well-preserved liver function. Nevertheless, the rate of postoperative recurrence at 5 years is as high as 70%, and this gravely jeopardizes the therapeutic outcome. Clearly, new approaches are needed for preventing the relapse of this deadly disease. Taking advantage of a luciferase-labeled orthotopic xenograft model of HCC, we examined the role of sorafenib, the first systemic drug approved for advanced HCC patients, in the prevention of HCC recurrence. We found that sorafenib suppressed the development of postsurgical intrahepatic recurrence and abdominal metastasis and consequently led to prolonged postoperative survival of mice in this model. Furthermore, hyperactivity of extracellular signal-regulated kinase signaling caused by elevated levels of growth factors associated with postoperative liver regeneration enhanced the sensitivity of HCC cells to sorafenib; this provides a plausible explanation for the observation that recurrent tumors are more responsive to growth inhibition by sorafenib. CONCLUSION: Our results strongly suggest that by effectively reducing postoperative recurrence, sorafenib has a potential application in early-stage HCC patients who have undergone hepatectomy with curative intention.

IRF-2 is over-expressed in pancreatic cancer and promotes the growth of pancreatic cancer cells.

Pancreatic cancer is one of the most malignant diseases in the world. Interferon regulator factor 2 (IRF-2), an interferon regulatory factor, has been known to act as an oncogene in distinct types of cancer. In this study, we found that the expression of IRF-2 was up-regulated in primary pancreatic cancer samples and associated with tumor size, differentiation, tumor-node-metastasis stage, and survival of the patients. In pancreatic cancer cells, knockdown on the expression of IRF-2 inhibited cell growth in the liquid culture and on the soft agar. Mechanistically, IRF-2 modulated the growth of pancreatic cancer cells through regulating proliferation and apoptosis effectors, such as cyclin D1 and BAX. Collectively, these results suggest that IRF-2 plays an important role in the tumorigenesis of pancreatic cancer and down-regulation of IRF-2 would be a new treatment target for pancreatic cancer.

CCN1 promotes tumorigenicity through Rac1/Akt/NF-κB signaling pathway in pancreatic cancer.

Aberrant CCN1 expression has been reported to play an important role in the tumor development. However, the pattern and the role of CCN1 in pancreatic cancer remain largely unknown. Therefore, we further deciphered the role CCN1 played in pancreatic cancer. We first evaluated the CCN1 expression in human pancreatic cancer tissues and pancreatic cancer cells. Then we forced expression and silenced CCN1 expression in pancreatic cancer cell lines MIA PaCa2 and PANC-1 respectively, using lentivirus vectors. We characterized the stable cells in vitro and in vivo using a nude mouse xenograft model. In this study, we found that CCN1 expression was significantly higher in cancer specimens which positively correlated with the expression level of phosphorylated Akt and p65. and poorer outcome. Moreover, our results demonstrated that CCN1 positively regulated pancreatic cell growth in vitro and in vivo and helped cancer cells resist to tumor necrosis factor alpha-induced apoptosis. Furthermore, we disclosed that activation of CCN1/ras-related c3 botulinum toxin substrate 1 (Rac1)/V-akt murine thymoma viral oncogene homolog (Akt)/nuclear factor-kappa B pathway inhibited apoptosis in pancreatic cancer cells. CCN1 is upregulated in pancreatic cancer and promotes the survival of pancreatic cancer cells. Taken together, these results indicate that CCN1 may be a potential target for pancreatic cancer therapy.

VRK2 activates TNFα/NF-κB signaling by phosphorylating IKKß in pancreatic cancer.

NF-κB signaling is active in more than 50% of patients with pancreatic cancer and plays an important role in promoting the progression of pancreatic cancer. Revealing the activation mechanism of NF-κB signaling is important for the treatment of pancreatic cancer. In this study, the regulation of TNFα/NF-κB signaling by VRK2 (vaccinia-related kinase 2) was investigated. The levels of VRK2 protein were examined by immunohistochemistry (IHC). The functions of VRK2 in the progression of pancreatic cancer were examined using CCK8 assay, anchorage-independent assay, EdU assay and tumorigenesis assay. The regulation of VRK2 on the NF-κB signaling was investigated by immunoprecipitation and invitro kinase assay. It was discovered in this study that the expression of VRK2 was upregulated in pancreatic cancer and that the VRK2 expression level was significantly correlated with the pathological characteristics and the survival time of patients. VRK2 promoted the growth, sphere formation and subcutaneous tumorigenesis of pancreatic carcinoma cells as well as the organoid growth derived from the pancreatic cancer mouse model. Investigation of the molecular mechanism indicated that VRK2 interacts with IKKß, phosphorylating its Ser177 and Ser181 residues and thus activating the TNFα/NF-κB signaling pathway. An IKKß inhibitors abolished the promotive effect of VRK2 on the growth of organoids. The findings of this study indicate that VRK2 promotes the progression of pancreatic cancer by activating the TNFα/NF-κB signaling pathway, suggesting that VRK2 is a potential therapeutic target for pancreatic cancer.

Asparagine synthetase regulates lung-cancer metastasis by stabilizing the ß-catenin complex and modulating mitochondrial response.

The availability of asparagine is the limitation of cell growth and metastasis. Asparagine synthetase (ASNS) was an essential enzyme for endogenous asparagine products. In our study, ASNS-induced asparagine products were essential to maintain tumor growth and colony formations in vitro. But mutated ASNS which defected endogenous asparagine products still upregulated cell invasiveness, which indicated that ASNS promoted invasiveness by alternative pathways. Mechanically, ASNS modulated Wnt signal transduction by promoting GSK3ß phosphorylation on ser9 and stabilizing the ß-catenin complex, as result, ASNS could promote more ß-catenin translocation into nucleus independent of endogenous asparagine. At the same time, ASNS modulated mitochondrial response to Wnt stimuli with increased mitochondrial potential and membrane fusion. In summary, ASNS promoted metastasis depending on Wnt pathway and mitochondrial functions even without endogenous asparagine products.

Pantothenate Kinase 1 Inhibits the Progression of Hepatocellular Carcinoma by Negatively Regulating Wnt/ß-catenin Signaling.

Hyperactivation of Wnt/ß-catenin signaling has been reported in hepatocellular carcinoma (HCC). However, the mechanisms underlying the hyperactivation of Wnt/ß-catenin signaling are incompletely understood. In this study, Pantothenate kinase 1 (PANK1) is shown to be a negative regulator of Wnt/ß-catenin signaling. Downregulation of PANK1 in HCC correlates with clinical features. Knockdown of PANK1 promotes the proliferation, growth and invasion of HCC cells, while overexpression of PANK1 inhibits the proliferation, growth, invasion and tumorigenicity of HCC cells. Mechanistically, PANK1 binds to CK1α, exerts protein kinase activity and cooperates with CK1α to phosphorylate N-terminal serine and threonine residues in ß-catenin both in vitro and in vivo. Additionally, the expression levels of PANK1 and ß-catenin can be used to predict the prognosis of HCC. Collectively, the results of this study highlight the crucial roles of PANK1 protein kinase activity in inhibiting Wnt/ß-catenin signaling, suggesting that PANK1 is a potential therapeutic target for HCC.