The oncoprotein HBXIP up-regulates YAP through activation of transcription factor c-Myb to promote growth of liver cancer

Oncoprotein LAMTOR5-mediated CHOP silence via DNA hypermethylation and miR-182/miR-769 in promotion of liver cancer growth

C/EBP homologous protein (CHOP) triggers the death of multiple cancers via endoplasmic reticulum (ER) stress. However, the function and regulatory mechanism of CHOP in liver cancer remain elusive. We have reported that late endosomal/lysosomal adapter, mitogen-activated protein kinase and mTOR activator 5 (LAMTOR5) suppresses apoptosis in various cancers. Here, we show that the transcriptional and posttranscriptional inactivation of CHOP mediated by LAMTOR5 accelerates liver cancer growth. Clinical bioinformatic analysis revealed that the expression of CHOP was low in liver cancer tissues and that its increased expression predicted a good prognosis. Elevated CHOP contributed to destruction of LAMTOR5-induced apoptotic suppression and proliferation. Mechanistically, LAMTOR5-recruited DNA methyltransferase 1 (DNMT1) to the CpG3 region (-559/-429) of the CHOP promoter and potentiated its hypermethylation to block its interaction with general transcription factor IIi (TFII-I), resulting in its inactivation. Moreover, LAMTOR5-enhanced miR-182/miR-769 reduced CHOP expression by targeting its 3'UTR. Notably, lenvatinib, a first-line targeted therapy for liver cancer, could target the LAMTOR5/CHOP axis to prevent liver cancer progression. Accordingly, LAMTOR5-mediated silencing of CHOP via the regulation of ER stress-related apoptosis promotes liver cancer growth, providing a theoretical basis for the use of lenvatinib for the treatment of liver cancer.

HBXIP induces PARP1 via WTAP-mediated m6A modification and CEBPA-activated transcription in cisplatin resistance to hepatoma

Poly (ADP-ribose) polymerase 1 (PARP1) is a DNA-binding protein that is involved in various biological functions, including DNA damage repair and transcription regulation. It plays a crucial role in cisplatin resistance. Nevertheless, the exact regulatory pathways governing PARP1 have not yet been fully elucidated. In this study, we present evidence suggesting that the hepatitis B X-interacting protein (HBXIP) may exert regulatory control over PARP1. HBXIP functions as a transcriptional coactivator and is positively associated with PARP1 expression in tissues obtained from hepatoma patients in clinical settings, and its high expression promotes cisplatin resistance in hepatoma. We discovered that the oncogene HBXIP increases the level of PARP1 m6A modification by upregulating the RNA methyltransferase WTAP, leading to the accumulation of the PARP1 protein. In this process, on the one hand, HBXIP jointly activates the transcription factor ETV5, promoting the activation of the WTAP promoter and further facilitating the promotion of the m6A modification of PARP1 by WTAP methyltransferase, enhancing the RNA stability of PARP1. On the other hand, HBXIP can also jointly activate the transcription factor CEBPA, enhance the activity of the PARP1 promoter, and promote the upregulation of PARP1 expression, ultimately leading to enhanced DNA damage repair capability and promoting cisplatin resistance in hepatoma. Notably, aspirin inhibits HBXIP, thereby reducing the expression of PARP1. Overall, our research revealed a novel mechanism for increasing PARP1 abundance, and aspirin therapy could overcome cisplatin resistance in hepatoma.

Role of CELF2 in ferroptosis: Potential targets for cancer therapy (Review)

Ferroptosis is a novel form of regulated cellular necrosis that plays a critical role in promoting cancer progression and developing drug resistance. The main characteristic of ferroptosis is iron‑dependent lipid peroxidation caused by excess intracellular levels of reactive oxygen species. CUGBP ELAV‑like family number 2 (CELF2) is an RNA‑binding protein that is downregulated in various types of cancer and is associated with poor patient prognoses. CELF2 can directly bind mRNA to a variety of ferroptosis control factors; however, direct evidence of the regulatory role of CELF2 in ferroptosis is currently limited. The aim of the present review was to summarise the findings of previous studies on CELF2 and its role in regulating cellular redox homeostasis. The present review may provide insight into the possible mechanisms through which CELF2 affects ferroptosis and to provide recommendations for future studies.

Sorafenib triggers ferroptosis via inhibition of HBXIP/SCD axis in hepatocellular carcinoma

Sorafenib, which inhibits multiple kinases, is an effective frontline therapy for hepatocellular carcinoma (HCC). Ferroptosis is a form of iron-dependent programmed cell death regulated by lipid peroxidation, which can be induced by sorafenib treatment. Oncoprotein hepatitis B X-interacting protein (HBXIP) participates in multiple biological pro-tumor processes, including growth, metastasis, drug resistance, and metabolic reprogramming. However, the role of HBXIP in sorafenib-induced ferroptotic cell death remains unclear. In this study, we demonstrated that HBXIP prevents sorafenib-induced ferroptosis in HCC cells. Sorafenib decreased HBXIP expression, and overexpression of HBXIP blocked sorafenib-induced HCC cell death. Interestingly, suppression of HBXIP increased malondialdehyde (MDA) production and glutathione (GSH) depletion to promote sorafenib-mediated ferroptosis and cell death. Ferrostatin-1, a ferroptosis inhibitor, reversed the enhanced anticancer effect of sorafenib caused by HBXIP silencing in HCC cells. Regarding the molecular mechanism, HBXIP transcriptionally induced the expression of stearoyl-CoA desaturase (SCD) via coactivating the transcriptional factor ZNF263, resulting in the accumulation of free fatty acids and suppression of ferroptosis. Functionally, activation of the HBXIP/SCD axis reduced the anticancer activity of sorafenib and suppressed ferroptotic cell death in vivo and in vitro. HBXIP/SCD axis-mediated ferroptosis can serve as a novel downstream effector of sorafenib. Our results provide new evidence for clinical decisions in HCC therapy.

HBXIP blocks myosin-IIA assembly by phosphorylating and interacting with NMHC-IIA in breast cancer metastasis

Tumor metastasis depends on the dynamic balance of the actomyosin cytoskeleton. As a key component of actomyosin filaments, non-muscle myosin-IIA disassembly contributes to tumor cell spreading and migration. However, its regulatory mechanism in tumor migration and invasion is poorly understood. Here, we found that oncoprotein hepatitis B X-interacting protein (HBXIP) blocked the myosin-IIA assemble state promoting breast cancer cell migration. Mechanistically, mass spectrometry analysis, co-immunoprecipitation assay and GST-pull down assay proved that HBXIP directly interacted with the assembly-competent domain (ACD) of non-muscle heavy chain myosin-IIA (NMHC-IIA). The interaction was enhanced by NMHC-IIA S1916 phosphorylation via HBXIP-recruited protein kinase PKCβII. Moreover, HBXIP induced the transcription of PRKCB, encoding PKCβII, by coactivating Sp1, and triggered PKCβII kinase activity. Interestingly, RNA sequencing and mouse metastasis model indicated that the anti-hyperlipidemic drug bezafibrate (BZF) suppressed breast cancer metastasis via inhibiting PKCβII-mediated NMHC-IIA phosphorylation in vitro and in vivo. We reveal a novel mechanism by which HBXIP promotes myosin-IIA disassembly via interacting and phosphorylating NMHC-IIA, and BZF can serve as an effective anti-metastatic drug in breast cancer.

Advances in prognostic and therapeutic targets for hepatocellular carcinoma and intrahepatic cholangiocarcinoma: The hippo signaling pathway

Primary liver cancer is the sixth most frequently diagnosed cancer worldwide and the third leading cause of cancer-related death. The majority of the primary liver cancer cases are hepatocellular carcinoma and intrahepatic cholangiocarcinoma. Worldwide, there is an increasing incidence of primary liver cancer cases due to multiple risk factors ranging from parasites and viruses to metabolic diseases and lifestyles. Often, patients are diagnosed at advanced stages, depriving them of surgical curability benefits. Moreover, the efficacy of the available chemotherapeutics is limited in advanced stages. Furthermore, tumor metastases and recurrence make primary liver cancer management exceptionally challenging. Thus, exploring the molecular mechanisms for the development and progression of primary liver cancer is critical in improving diagnostic, treatment, prognostication, and surveillance modalities. These mechanisms facilitate the discovery of specific targets that are critical for novel and more efficient treatments. Consequently, the Hippo signaling pathway executing a pivotal role in organogenesis, hemostasis, and regeneration of tissues, regulates liver cells proliferation, and apoptosis. Cell polarity or adhesion molecules and cellular metabolic status are some of the biological activators of the pathway. Thus, understanding the mechanisms exhibited by the Hippo pathway is critical to the development of novel targeted therapies. This study reviews the advances in identifying therapeutic targets and prognostic markers of the Hippo pathway for primary liver cancer in the past six years.

Hbxip is essential for murine embryogenesis and regulates embryonic stem cell differentiation through activating mTORC1

HBXIP, also named LAMTOR5, has been well characterized as a transcriptional co-activator in various cancers. However, the role of Hbxip in normal development remains unexplored. Here, we demonstrated that homozygous knockout of Hbxip leads to embryonic lethality, with retarded growth around E7.5, and that depletion of Hbxip compromises the self-renewal of embryonic stem cells (ESCs), with reduced expression of pluripotency genes, reduced cell proliferation and decreased colony-forming capacity. In addition, both Hbxip−/− ESCs and E7.5 embryos displayed defects in ectodermal and mesodermal differentiation. Mechanistically, Hbxip interacts with other components of the Ragulator complex, which is required for mTORC1 activation by amino acids. Importantly, ESCs depleted of Ragulator subunits, Lamtor3 or Lamtor4, displayed differentiation defects similar to those of Hbxip−/− ESCs. Moreover, Hbxip−/−, p14−/− and p18−/− mice, lacking subunits of the Ragulator complex, also shared similar phenotypes, embryonic lethality and retarded growth around E7-E8. Thus, we conclude that Hbxip plays a pivotal role in the development and differentiation of the epiblast, as well as the self-renewal and differentiation of ESCs, through activating mTORC1 signaling.

Methyl 6-O-cinnamoyl-α-d-glucopyranoside Ameliorates Acute Liver Injury by Inhibiting Oxidative Stress Through the Activation of Nrf2 Signaling Pathway

Excessive stimulation of hepatotoxins and drugs often lead to acute liver injury, while treatment strategies for acute liver injury have been limited. Methyl 6-O-cinnamoyl-α-d-glucopyranoside (MCGP) is a structure modified compound from cinnamic acid, a key chemical found in plants with significant antioxidant, anti-inflammatory, and antidiabetic effects. In this study, we investigated the effects and underlying mechanisms of MCGP on acetaminophen (APAP)- or carbon tetrachloride (CCl₄)-induced acute liver injury. As a result, MCGP inhibited cell death and apoptosis induced by APAP or CCl₄, and suppressed the reactive oxygen species (ROS) generation stimulated by H₂O₂ in liver AML12 cells. In vivo, MCGP alleviated APAP/CCl₄-induced hepatic necrosis and resumed abnormal aminotransferase activities and liver antioxidase activities. In addition, MCGP depressed APAP- or CCl₄-induced oxidative stress through the suppression of CYP2E1 and activation of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. MCGP also enhanced the number of PCNA-positive hepatocytes, increased hepatic PCNA and Bcl-XL, and decreased BAX expression in APAP-/CCl₄-intoxicated mice. Furthermore, MCGP activated the GSDMD-N/cleaved caspase 1 pathway. In summary, MCGP might act as a potential therapeutic drug against drug-induced and chemical-induced acute liver injuries, and its underlying mechanisms might engage on the pressing of oxidative stress, refraining of hepatocyte apoptosis, and facilitating of liver regeneration.

HTLV-1 activates YAP via NF-κB/p65 to promote oncogenesis

The Hippo pathway plays critical roles in controlling cell proliferation, and its dysregulation is widely implicated in numerous human cancers. YAP, a Hippo signaling effector, often acts as a nexus and integrator for multiple prominent signaling networks. In this study, we discover NF-κB cross talk with the Hippo pathway and identify p65 as a critical regulator for YAP nuclear retention and transcriptional activity. Furthermore, we find that p65-induced YAP activation is essential for maintaining the proliferation of ATL cells in vitro and in vivo. Our findings unravel the functional interplay between NF-κB and YAP signaling and provide mechanistic insights into the YAP-dependent growth control pathway and tumorigenesis.

Adult T-cell leukemia/lymphoma (ATL) is an aggressive malignancy caused by human T-cell leukemia virus type 1 (HTLV-1) infection. HTLV-1 exerts its oncogenic functions by interacting with signaling pathways involved in cell proliferation and transformation. Dysregulation of the Hippo/YAP pathway is associated with multiple cancers, including virus-induced malignancies. In the present study, we observe that expression of YAP, which is the key effector of Hippo signaling, is elevated in ATL cells by the action of the HTLV-1 Tax protein. YAP transcriptional activity is remarkably enhanced in HTLV-1–infected cells and ATL patients. In addition, Tax activates the YAP protein via a mechanism involving the NF-κB/p65 pathway. As a mechanism for this cross talk between the Hippo and NF-κB pathways, we found that p65 abrogates the interaction between YAP and LATS1, leading to suppression of YAP phosphorylation, inhibition of ubiquitination-dependent degradation of YAP, and YAP nuclear accumulation. Finally, knockdown of YAP suppresses the proliferation of ATL cells in vitro and tumor formation in ATL-engrafted mice. Taken together, our results suggest that p65-induced YAP activation is essential for ATL pathogenesis and implicate YAP as a potential therapeutic target for ATL treatment.

The modulation of PD-L1 induced by the oncogenic HBXIP for breast cancer growth

Programmed death ligand-1 (PD-L1)/PD-1 checkpoint extensively serves as a central mediator of immunosuppression. A tumor-promoting role for abundant PD-L1 in several cancers is revealed. However, the importance of PD-L1 and how the PD-L1 expression is controlled in breast cancer remains obscure. Here, the mechanisms of controlling PD-L1 at the transcription and protein acetylation levels in promoting breast cancer growth are presented. Overexpressed PD-L1 accelerates breast cancer growth in vitro and in vivo. RNA-seq uncovers that PD-L1 can induce some target genes affecting many cellular processes, especially cancer development. In clinical breast cancer tissues and cells, PD-L1 and HBXIP are both increased, and their expressions are positively correlated. Mechanistic exploration identifies that HBXIP stimulates the transcription of PD-L1 through co-activating ETS2. Specifically, HBXIP induces PD-L1 acetylation at K270 site through interacting with acetyltransferase p300, leading to the stability of PD-L1 protein. Functionally, depletion of HBXIP attenuates PD-L1-accelerated breast tumor growth. Aspirin alleviates breast cancer via targeting PD-L1 and HBXIP. Collectively, the findings display new light into the mechanisms of controlling tumor PD-L1 and broaden the utility for PD-L1 as a target in breast cancer therapy.

The JAK2 inhibitor TG101209 exhibits anti-tumor and chemotherapeutic sensitizing effects on Burkitt lymphoma cells by inhibiting the JAK2/STAT3/c-MYB signaling axis

Constitutive activation of JAK2/STAT3 is a major oncogenic signaling event involved in the development of Burkitt lymphoma (BL). In the present study, we investigated the antilymphoma activity of TG101209, a specific JAK2 inhibitor, on EBV-positive and EBV-negative Burkitt lymphoma cell lines and primary BL cells. The results showed that TG101209 had a significant antilymphoma effect by inhibiting BL cell growth and inducing apoptosis along with cell differentiation toward mature B cells in vitro. We also found that TG101209 displayed significant synergistic action and a sensitizing effect on the anti-Burkitt lymphoma activity of doxorubicin. In vivo experiments indicated that TG101209 could suppress tumor growth and prolong the overall survival of BL cell-bearing mice. The mechanistic study indicated that TG101209, by suppressing the JAK2/STAT3/c-MYB signaling axis and crosstalk between the downstream signaling pathways, plays an antilymphoma role. These data suggested that TG101209 may be a promising agent or alternative choice for the treatment of BL.

HBXIP accelerates glycolysis and promotes cancer angiogenesis via AKT/mTOR pathway in bladder cancer

Abnormal metabolism and uncontrolled angiogenesis are two important characteristics of malignant tumors. Although HBXIP is known to be associated with a poor prognosis for bladder cancer (BC), its effects on glycolysis and angiogenesis in BC have not been investigated. BC prognosis and relative gene expression of HBXIP were analyzed using the GEPIA, UALCAN, and STRING databases. BC cell angiogenesis and glycolysis were assessed by vasculogenic mimicry and glycolysis assay. Human umbilical vein endothelial cell (HUVEC) viability, migration, and angiogenesis were assessed by CCK8, transwell, wound healing, and tube formation assays. The results showed that HBXIP was highly expressed in BC tissues and cells. Knockdown of HBXIP expression decreased the levels of glucose uptake, lactate production, and glycolytic enzyme expression in BC cells, and decreased cell viability and migration of HUVECs. Additionally, silencing HBXIP reduced the total length of tubes and number of intersections, and EPO and VEGF protein expression in BC cells and HUVECs. Furthermore, knockdown of HBXIP expression reversed cell viability, migration, tube formation, and vasculogenic mimicry under high glucose and lactate conditions. Mechanistically, silencing of HBXIP reduced the protein expression levels of pAKT-ser473 and pmTOR, and inhibition of HBXIP, AKT, and mTOR expression decreased glycolytic enzyme protein expression. Our findings suggest that HBXIP reduces glycolysis in BC cells via regulation of AKT/mTOR signaling, thereby blocking BC angiogenesis. Collectively, this study provides a potential strategy to target HBXIP and AKT/mTOR for regulating glycolysis progression concurrently with anti-angiogenesis effects, and thereby develop novel therapeutics for the treatment of BC.

lncRNA LOC102724169 plus cisplatin exhibit the synergistic anti-tumor effect in ovarian cancer with chronic stress

Chronic stress has been proven to accelerate the development and progression of ovarian cancer, but the underlying molecular mechanisms have not been fully elucidated. In a combination survey of ovarian cancer with chronic stress (OCCS) mouse models and high-throughput sequencing, a key lncRNA named LOC102724169 on chromosome 6q27 has been identified, which functions as a dominant tumor suppressor in OCCS. Transcriptionally regulated by CCAAT enhancer binding protein (CEBP) beta (CEBPB), LOC102724169 shows low expression and correlates with poor progression-free survival (PFS) in OCCS patients. LOC102724169 is an instructive molecular inhibitor of malignancy of ovarian cancer cells, which is necessary to improve the curative effect of cisplatin therapy on ovarian cancer. This function stems from the inactivation of molecules in phosphatidylinositol 3-kinase (PI3K)/AKT signaling, repressing MYB expression and retaining the responsiveness of cancer cells to cisplatin. These findings provide a mechanistic understanding of the synergistic anti-tumor purpose of LOC102724169 as a bona fide tumor suppressor, enhancing the therapeutic effect of cisplatin. The new regulatory model of “lncRNA-MYB” provides new perspectives for LOC102724169 as a chronic stress-related molecule and also provides mechanistic insight into exploring the cancer-promoting mechanism of MYB in OCCS, which may be a promising therapeutic strategy for ovarian cancer.

Oncoprotein HBXIP promotes tumorigenesis through MAPK/ERK pathway activation in non-small cell lung cancer

Objective:

The oncoprotein, hepatitis B X-interacting protein (HBXIP), has been reported to play an important role in human malignancies. However, its functions in non-small cell lung cancer (NSCLC) are poorly understood. The goal of the present study was to identify the role of HBXIP in the regulation of NSCLC development.

Methods:

The level of HBXIP expression in NSCLC tissue was assessed by immunohistochemical and Western blot analyses, and its relationships with clinicopathological features and outcomes were statistically evaluated. The effects of HBXIP on NSCLC cell progression were assessed through cell viability, colony formation, and flow cytometry analyses in vitro. The mechanism by which HBXIP regulated the MAPK pathway was studied by Western blot, immunofluorescence, and immunoprecipitation assays. In addition, in vivo experiments were performed to evaluate the progression of NSCLC and ERK signaling pathway activation after HBXIP knockdown.

Results:

HBXIP was overexpressed in human NSCLC and was correlated with the invasiveness of NSCLC. The high expression of HBXIP in NSCLC was significantly correlated with gender (P = 0.033), N stage (P = 0.002), and tumor-node-metastasis stage (P = 0.008). In vitro experiments using an NSCLC cell line revealed that HBXIP knockdown resulted in the suppression of cell proliferation and colony formation, which was consistent with the enhanced cell cycle arrest in G1 phase. The results of a mechanistic investigation suggested that binding of HBXIP to MEK1 protein promoted MAPK/ERK signaling pathway activation in NSCLC by preventing the proteasome-mediated degradation of MEK1. In addition, the results obtained using in vivo subcutaneous tumor xenografts confirmed that HBXIP deficiency decreased MEK1 protein levels and NSCLC tumor growth.

Conclusions:

Taken together, our results showed that the HBXIP-MEK interaction promoted oncogenesis via the MAPK/ERK pathway, which may serve as a novel therapeutic target for cancers in which MAPK/ERK signaling is a dominant feature.

Intra-platelet serotonin and YAP contributed to poor prognosis of hepatocellular carcinoma

AIMS

Intra-platelet 5-HT (IP 5-HT) and YAP exhibit an important role in hepatocellular carcinoma (HCC). The aim of the study was to investigate whether IP 5-HT and YAP could affect the progression and prognosis of HCC.

METHODS

5-HT level and YAP expression were measured and were compared between HCC patients and control patients. By grouping HCC patients, we analyzed clinical indicators and survival. The predictive nomogram was established by R software according to the risk factors obtained from multivariate analysis.

RESULTS

Higher IP 5-HT level and higher YAP expression were associated with poorer prognosis. In addition, they were also associated with BCLC stages. Higher IP 5-HT was found to be related with higher international normalized ratio (INR) (p = 0.040), more death (p = 0.015) and higher YAP expression (p < 0.001). Similarly, higher YAP expression was proved to be associated with lower platelet counts (PLT) (p = 0.032), smaller tumor size (p = 0.017), more death (p < 0.001) and higher IP 5-HT (p < 0.001). In addition, alkaline phosphatase (ALP), YAP and tumor size were proved to be independent risk factors. By using risk factors, we have established a prognostic prediction nomogram for HCC patients. In the prognostic prediction nomogram, patients with higher scores would have poorer prognosis.

CONCLUSIONS

IP 5-HT and YAP might affect the progression and prognosis of HCC through synergistic effect. Moreover, IP 5-HT might affect HCC by regulating YAP expression. Thus, both of them might be potential therapeutic targets. By establishing the prognostic prediction nomogram, we could improve the prediction system.

HBXIP drives metabolic reprogramming in hepatocellular carcinoma cells via METTL3-mediated m6A modification of HIF-1α

Cancer cells sustain high levels of glycolysis and glutaminolysis via reprogramming of intracellular metabolism, which represents a driver of hepatocellular carcinoma (HCC) progression. Understanding the mechanisms of cell metabolic reprogramming may present a new basis for liver cancer treatment. Herein, we collected HCC tissues and noncancerous liver tissues and found hepatitis B virus X-interacting protein (HBXIP) was found to be upregulated in HCC tissues and associated with poor prognosis. The N6-methyladenosine (m6A) level of hypoxia-inducible factor-1α (HIF-1α) in HCC cells was evaluated after the intervention of METTL3. The possible m6A site of HIF-1α was queried and the binding relationship between METTL3 and HIF-1α was verified. The interference of HBXIP suppressed HCC malignant behaviors and inhibited the Warburg effect in HCC cells. METTL3 was upregulated in HCC tissues and positively regulated by HBXIP. Overexpression of METTL3 restored cell metabolic reprogramming in HCC cells with partial loss of HBXIP. HBXIP mediated METTL3 to promote the metabolic reprogramming and malignant biological behaviors of HCC cells. The levels of total m6A in HCC cells and m6A in HIF-1α were increased. METTL3 had a binding relationship with HIF-1α and mediated the m6A modification of HIF-1α. In conclusion, HBXIP drives metabolic reprogramming in HCC cells via METTL3-mediated m6A modification of HIF-1α.

The oncogenic role of HBXIP

Hepatitis B X-interacting protein (HBXIP) is a conserved protein of 19 kDa that was originally identified as a binding partner of hepatitis B virus X protein. Emerging evidence indicates that HBXIP is highly expressed in a variety of cancers and is correlated with poor clinical outcomes in cancer patients. HBXIP plays a critical role in cancer progression, but the underlying mechanisms are still unclear. In this review, we primarily focus on publications investigating HBXIP in cancer research, including its expression and clinical significance in cancer patients, its role as a coactivator of transcription factors in cancer cells, its inhibitory effects on the mitochondrial cytochrome c-caspase apoptotic pathway, as well as its roles in promoting mitosis and drug resistance in cancer cells, its regulatory effects on cancer metabolism, and its relationships with other signaling pathways or microRNAs in cancer. This review aims to compile and summarize existing knowledge of the functions of HBXIP in cancer, which provides a comprehensive reference for future studies on the oncogenic mechanisms of HBXIP.

YAP1 Promotes Tumor Invasion and Metastasis in Nasopharyngeal Carcinoma with Hepatitis B Virus Infection

INTRODUCTION

Nasopharyngeal carcinoma (NPC) patients with HBsAg (+) commonly present with high frequencies of distant metastasis and poor survival rate; however, the mechanism has not been elucidated.

MATERIALS AND METHODS

We analyzed the yes-associated protein 1 (YAP1) expression between HBsAg (+) and HBsAg (-) of NPC patients, then analyzed the relationship of YAP1 with survival. We further explored the anti-tumor role in NPC cell lines using YAP1 siRNA technique, and checked whether YAP1 regulatesepithelial-mesenchymal transition ( EMT). The relationship between HBV X protein (HBx) and YAP1 was also tested using Dual-Luciferase reporter assay. Finally, we explored anti-YAP1 to inhibit tumor metastasis using the xenograft mice model.

RESULTS

In the current study, we found that YAP1 expression was higher in HBsAg (+) samples than in the HBsAg (-) samples, as a clinical signature, suggesting that YAP1 could be used as a prognostic factor for NPC. Our results showed that the HBx could regulate YAP1, further promoting cellular invasiveness through EMT. Anti-YAP1 can also decrease metastasis in vivo.

CONCLUSION

Our findings suggest that YAP1 is a promising prognostic factor in NPC and could be used as a potential treatment target for NPC with HBV infection.

HBXIP Regulates Gastric Cancer Glucose Metabolism and Malignancy Through PI3K/AKT and p53 Signaling

Introduction

Hepatitis B X-interacting protein (HBXIP) overexpression is related to the progression of multiple cancers. However, its role in gastric cancer (GC) remains unclear.

Materials and Methods

HBXIP expression was determined in human GC specimens and cell lines by quantitative polymerase chain reaction (qRT-PCR) and Western blot. The effects of HBXIP depletion or ectopic expression on GC proliferation were evaluated in vitro using the cell counting kit-8 (CCK-8), 5-ethynyl-2ʹ-deoxyuridine (EdU) incorporation, colony formation, and cell cycle assays. The in vivo effects were investigated using a mouse xenograft model. Apoptosis was evaluated by flow cytometry (in vitro) and immunohistochemistry (IHC; in vivo). Cell migration and invasion were evaluated in vitro using wound healing, transwell migration, and matrigel invasion assays; and in vivo by quantifying distant metastases from injection of GC cells in the lateral tail vein.

Results

Herein, we reported that HBXIP expression was higher in GC than in normal tissues, and this high expression indicated a poorer prognosis. Gain- and loss-of-function assays showed that HBXIP promoted GC proliferation, migration, and invasion, and inhibited apoptosis. High-performance liquid chromatography (HPLC) quantification of glycolytic metabolites revealed that HBXIP promoted glucose metabolic reprogramming. Investigation of the PI3K/AKT and p53 pathways highlighted their role in this HBXIP-mediated metabolic reprogramming.

Conclusion

Our results indicate that the up-regulation of HBXIP leads to GC progression by positively regulating glucose metabolism. Therefore, HBXIP is a potential target for the treatment of GC.

A novel lncRNA PLK4 up-regulated by talazoparib represses hepatocellular carcinoma progression by promoting YAP-mediated cell senescence

A growing number of studies recognize that long non‐coding RNAs (lncRNAs) are essential to mediate multiple tumorigenic processes, including hepatic tumorigenesis. However, the pathological mechanism of lncRNA‐regulated liver cancer cell growth remains poorly understood. In this study, we identified a novel function lncRNA, named polo‐like kinase 4 associated lncRNA (lncRNA PLK4, GenBank Accession No. RP11‐50D9.3), whose expression was dramatically down‐regulated in hepatocellular carcinoma (HCC) tissues and cells. Interestingly, talazoparib, a novel and highly potent poly‐ADP‐ribose polymerase 1/2 (PARP1/2) inhibitor, could increase lncRNA PLK4 expression in HepG2 cells. Importantly, we showed that talazoparib‐induced lncRNA PLK4 could function as a tumour suppressor gene by Yes‐associated protein (YAP) inactivation and induction of cellular senescence to inhibit liver cancer cell viability and growth. In summary, our findings reveal the molecular mechanism of talazoparib‐induced anti‐tumor effect, and suggest a potential clinical use of talazoparib‐targeted lncRNA PLK4/YAP‐dependent cellular senescence for the treatment of HCC.

HBXIP: a potential prognosis biomarker of colorectal cancer which promotes invasion and migration via epithelial-mesenchymal transition

Hepatitis B X-interacting protein (HBXIP) is highly expressed in many cancers, but the correlation between the expression of HBXIP and the clinical significance and underlying molecular mechanisms in colorectal cancer (CRC) is still unclear. We selected 186 specimens from CRC patients for analyzing the relationship between the expression of HBXIP and the clinical-pathological features by immunohistochemistry. Migration and invasion experiments were performed to examine the effect of HBXIP on CRC cell metastasis. Besides, we also explored the possible molecular mechanism of HBXIP regulation of CRC cell metastasis by Western blot. Our data indicated that the HBXIP was overexpressed in CRC tissues. High HBXIP expression was correlated with metastasis and shorter survival times in patients with CRC and served as an independent factor for poor prognosis. Moreover, HBXIP promotes CRC metastasis by enhancing the epithelial-mesenchymal transition (EMT) process. Our findings provide the first evidence that HBXIP induces EMT to promote metastasis and predicts the poor prognosis of CRC. Therefore, HBXIP may become a new target for CRC treatment.

The Hippo Pathway and Viral Infections

The Hippo signaling pathway is a novel tumor suppressor pathway, initially found in Drosophila. Recent studies have discovered that the Hippo signaling pathway plays a critical role in a wide range of biological processes, including organ size control, cell proliferation, cancer development, and virus-induced diseases. In this review, we summarize the current understanding of the biological feature and pathological role of the Hippo pathway, focusing particularly on current findings in the function of the Hippo pathway in virus infection and pathogenesis.

c-Myb promotes growth and metastasis of colorectal cancer through c-fos-induced epithelial-mesenchymal transition

c-Myb is a crucial transcription factor that participates in various biological functions; however, its role in colorectal cancer (CRC) remains poorly investigated. We first analyzed the expression and clinical significance of c-Myb in a retrospective cohort enrolling 132 CRC patients. Then, the CRISPR/Cas9 technique was used to establish c-Myb gene KO CRC cell lines. Cellular functional assays in vitro and in vivo were used to evaluate the impact of c-Myb KO in CRC cells. Finally, RNA sequencing was used to investigate the potential oncogenic mechanisms regulated by c-Myb in CRC progression and related cellular validations were accordingly carried out. As a result, c-Myb is significantly overexpressed in CRC tissues as compared with adjacent normal tissues. High expression of c-Myb is positively correlated with lymph node metastasis and poor prognosis. Univariate analysis and multivariate analysis further identify c-Myb as an independent unfavorable prognostic factor for CRC patients. c-Myb KO inhibits the proliferation, apoptosis resistance, invasion, metastasis, colony formation and in vivo tumorigenesis of CRC cells. Also, the mechanism investigation indicates that c-Myb may promote CRC progression by regulating c-fos. c-fos overexpression can rescue the inhibitory effect of c-Myb KO on the malignant characteristics of CRC cells. Finally, we find that c-Myb KO inhibits the epithelial-mesenchymal transition (EMT) molecular phenotype in CRC cells, whereas c-fos overexpression can rescue this inhibitory effect. This study suggests that c-Myb promotes the malignant progression of CRC through c-fos-induced EMT and has the potential to be a promising prognostic biomarker and therapeutic target.

The oncoprotein HBXIP facilitates metastasis of hepatocellular carcinoma cells by activation of MMP15 expression

Background: Due to the high recurrence and metastasis rate, the clinical outcomes of patients with hepatocellular carcinoma (HCC) are still unsatisfactory. Hepatitis B virus X-interacting protein (HBXIP) has been reported to play crucial roles in carcinogenesis.

Purpose: We aimed to reveal the functional significance and underlying mechanism of HBXIP in HCC metastasis. Methods: Cell transwell assay, in vivo metastasis model, real-time PCR, western blot analysis, luciferase reporter and chromatin immunoprecipitation assays were applied.

Results: Here, we detected the HBXIP expression level and determined its clinical significance in HCC. We found that HBXIP was significantly upregulated in HCC tissues, and correlated with vascular invasion, tumor metastasis and worse prognosis of HCC patients. HBXIP enhanced cell migration and invasion in vitro, and promoted the metastasis of HCC in vivo. Furthermore, we confirmed that HBXIP increased MMP15 expression through association with proto-oncogene c-myc. Depletion of c-myc abolished HBXIP-mediated MMP-15 upregulation. We also observed a positive correlation between HBXIP and MMP15 expression in HCC tissues.

Conclusion: Our results establish a novel function for HBXIP-MMP15 regulation in HCC metastasis and suggest its candidacy as a new prognostic biomarker and therapeutic target for HCC metastasis.

lncRNA B4GALT1-AS1 promotes colon cancer cell stemness and migration by recruiting YAP to the nucleus and enhancing YAP transcriptional activity

Here, an RNA-sequencing assay revealed long noncoding RNAs (lncRNAs) with an ectopic expression between colon cancer (CC) and normal colon epithelial cells, in which lncRNA B4GALT1-AS1 exhibited the highest change. A 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay indicated that B4GALT1-AS1 knockdown had no effect on CC cell viability, however, cell clone formation analysis showed that B4GALT1-AS1 knockdown attenuated the capacity of cell clone formation. Additionally, gene set enrichment analysis of this data set revealed that positive enrichment of stem cell-differentiated signatures and negative embryonic stem cell function and adult tissue stem module were observed in CC cells with B4GALT1-AS1 knockdown. Furthermore, B4GALT1-AS1 knockdown suppressed the stemness-marker expression, the ability of cell spheroid formation, and ALDH1 activity in CC cells. Mechanistically, RNA-sequencing data found that the Hippo pathway in cancer was shown on pathways mostly upregulated by B4GALT1-AS1 knockdown, and B4GALT1-AS1 directly bound to the yes-associated protein (YAP), a downstream executor of the Hippo pathway, and B4GALT1-AS1 knockdown promoted the nuclear cytoplasm translocation of YAP and decreased YAP transcriptional activity. Notably, YAP overexpression attenuated the inhibitory effects mediated by B4GALT1-AS1 knockdown. Our results identify the direct binding of lncRNA B4GALT1-AS1 to YAP, which is responsible for CC cell stemness.

MiR-145-targeted HBXIP modulates human breast cancer cell proliferation

BACKGROUND

MiR-145 has been identified as a tumor suppressive microRNA in multiple cancers. In this current investigation, we searched for new direct targets of miR-145 and evaluated their effect on breast cancer development.

METHODS

Targetscan was used to predict the target genes of miR-145. The targeting of miR-145 on oncogenic HBXIP was verified by luciferase reporter gene analysis. The effect of miR-145 on the level of messenger RNA and protein of HBXIP was evaluated by quantitative real-time PCR and immunoblotting. Correlations between miR-145 and HBXIP, as well as miR-145 expression, were analyzed in 30 paired breast cancer and noncancerous tissues by quantitative real-time PCR. Methyl thiazol tetrazolium and colony formation assays were applied to determine the cell proliferation ability.

RESULTS

HBXIP was identified as a novel target gene of miR-145 in breast cancer. MiR-145 was found to dose-dependently decrease messenger RNA and protein expression of HBXIP in breast cancer MCF-7 cells. Notably, miR-145 expression was negatively related to HBXIP expression and was obviously reduced in breast cancer samples. Finally, miR-145 suppressed cell proliferation while its inhibitor, anti-miR-145, accelerated cell proliferation. Interestingly, silencing of HBXIP reversed the acceleration of cell proliferation induced by anti-miR-145 in breast cancer.

CONCLUSION

Oncogenic HBXIP is a new direct target of tumor suppressive miR-145. Our findings reveal that miR-145-targeting HBXIP could be a potential therapeutic target in breast cancer.

Ajuba inhibits hepatocellular carcinoma cell growth via targeting of β-catenin and YAP signaling and is regulated by E3 ligase Hakai through neddylation

BACKGROUND

Aberrant activation of β-catenin and Yes-associated protein (YAP) signaling pathways has been associated with hepatocellular carcinoma (HCC) progression. The LIM domain protein Ajuba regulates β-catenin and YAP signaling and is implicated in tumorigenesis. However, roles and mechanism of Ajuba expression in HCC cells remain unclear. The E3 ligase Hakai has been shown to interact with other Ajuba family members and whether Hakai interacts and regulates Ajuba is unknown.

METHODS

HCC cell lines stably depleted of Ajuba or Hakai were established using lentiviruses expressing shRNAs against Ajuba or Hakai. The effects of Ajuba on HCC cells were determined by a number of cell-based analyses including anchorage-independent growth, three dimension cultures and trans-well invasion assay. In vivo tumor growth was determined in a xenograft model and Ajuba expression in tumor sections was examined by immunohistochemistry. Co-immunoprecipitation, confocal microscopy and immunoblot assay were used to examine the expression and interaction between Ajuba and Hakai.

RESULTS

Depletion of Ajuba in HCC cells significantly enhanced anchorage-independent growth, invasion, the formation of spheroids and tumor growth in a xenograft model, suggesting a tumor suppressor function for Ajuba in HCC. Mechanistically, Ajuba depletion triggered E-cadherin loss and β-catenin translocation with increased Cyclin D1 levels. In addition, depletion of Ajuba upregulated the levels of YAP and its target gene CYR61. Furthermore, siRNA-mediated knockdown of either β-catenin or YAP attenuated the pro-tumor effects by Ajuba depletion on HCC cells. Notably, Ajuba stability in HCC cells was regulated by Hakai, an E3 ligase for E-cadherin. Hakai interacted with Ajuba via its HYB domain and induced Ajuba neddylation, which was antagonized by the neddylation inhibitor, MLN4924, but not MG132. We further show that overexpression of Hakai in HCC cells markedly increased anchorage-independent growth, spheroid-formation ability and tumor growth in xenografts whereas Hakai depletion resulted in these opposite effects, indicating an oncogenic role for Hakai in HCC. Hakai also induced β-catenin translocation with increased levels of Cyclin D1.

CONCLUSIONS

Our data suggest a role for Ajuba and Hakai in HCC, and uncover the mechanism underlying the regulation of Ajuba stability.

Oncoprotein HBXIP enhances HOXB13 acetylation and co-activates HOXB13 to confer tamoxifen resistance in breast cancer

Background

Resistance to tamoxifen (TAM) frequently occurs in the treatment of estrogen receptor positive (ER+) breast cancer. Accumulating evidences indicate that transcription factor HOXB13 is of great significance in TAM resistance. However, the regulation of HOXB13 in TAM-resistant breast cancer remains largely unexplored. Here, we were interested in the potential effect of HBXIP, an oncoprotein involved in the acceleration of cancer progression, on the modulation of HOXB13 in TAM resistance of breast cancer.

Methods

The Kaplan-Meier plotter cancer database and GEO dataset were used to analyze the association between HBXIP expression and relapse-free survival. The correlation of HBXIP and HOXB13 in ER+ breast cancer was assessed by human tissue microarray. Immunoblotting analysis, qRT-PCR assay, immunofluorescence staining, Co-IP assay, ChIP assay, luciferase reporter gene assay, cell viability assay, and colony formation assay were performed to explore the possible molecular mechanism by which HBXIP modulates HOXB13. Cell viability assay, xenograft assay, and immunohistochemistry staining analysis were utilized to evaluate the effect of the HBXIP/HOXB13 axis on the facilitation of TAM resistance in vitro and in vivo.

Results

The analysis of the Kaplan-Meier plotter and the GEO dataset showed that mono-TAM-treated breast cancer patients with higher HBXIP expression levels had shorter relapse-free survivals than patients with lower HBXIP expression levels. Overexpression of HBXIP induced TAM resistance in ER+ breast cancer cells. The tissue microarray analysis revealed a positive association between the expression levels of HBXIP and HOXB13 in ER+ breast cancer patients. HBXIP elevated HOXB13 protein level in breast cancer cells. Mechanistically, HBXIP prevented chaperone-mediated autophagy (CMA)-dependent degradation of HOXB13 via enhancement of HOXB13 acetylation at the lysine 277 residue, causing the accumulation of HOXB13. Moreover, HBXIP was able to act as a co-activator of HOXB13 to stimulate interleukin (IL)-6 transcription in the promotion of TAM resistance. Interestingly, aspirin (ASA) suppressed the HBXIP/HOXB13 axis by decreasing HBXIP expression, overcoming TAM resistance in vitro and in vivo.

Conclusions

Our study highlights that HBXIP enhances HOXB13 acetylation to prevent HOXB13 degradation and co-activates HOXB13 in the promotion of TAM resistance of breast cancer. Therapeutically, ASA can serve as a potential candidate for reversing TAM resistance by inhibiting HBXIP expression.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0577-5) contains supplementary material, which is available to authorized users.

HBXIP activates the PPARδ/NF-κB feedback loop resulting in cell proliferation

Hepatitis B X-interacting protein (HBXIP, also termed as LAMTOR5) plays a crucial role in regulation of cancer progression, while the mechanism is still unclear. Here we found that HBXIP increased the expression of PPARδ (peroxisome proliferator-activated receptor-δ) in gene and protein levels of SW480 or HT-29 colonic cancer cells. Chromatin immunoprecipitation and luciferase reporter assays showed that HBXIP occupied the core promoter (−1079/−239 nt) regions of PPARδ and that HBXIP activated the transcription activity of PPARδ in an NF-κB (p65)-dependent manner. Moreover, Co-immunoprecipitation and immunofluorescence analysis showed that HBXIP bound to NF-κB/p65 in the cells. Interestingly, we found that PPARδ could conversely increase the expression of NF-κB/p65 through activating its transcription activity. In addition, the clinical observations showed that both HBXIP and PPARδ were highly expressed in colonic carcinoma, and HBXIP expression was positively associated with that of PPARδ in the clinical specimen. Importantly, HBXIP expression levels were positively correlated with the clinical pathological parameters including lymph node metastasis and advanced TNM stage. These findings suggest that HBXIP served as a co-activator to activate the positive feedback regulations of NF-κB/PPARδ, which promoted the fast proliferation of the colonic cancer cells. Therapeutically, HBXIP may serve as a potential drug target of colonic cancer cells.

HBXIP-elevated methyltransferase METTL3 promotes the progression of breast cancer via inhibiting tumor suppressor let-7g

Methyltransferase-like 3 (METTL3) is involved in RNA metabolism through N6-methyladenosine (m⁶A) modification. However, whether METTL3 participates in the progression of breast cancer is unclear. Aberrant expression of Mammalian hepatitis B X-interacting protein (HBXIP) drives the aggressiveness of breast cancer. Here, we are interested in the potential links between HBXIP and METTL3 in breast cancer. We showed that the expression of METTL3 was positively related to that of HBXIP in clinical breast cancer tissues. Moreover, HBXIP could up-regulate METTL3 in breast cancer cells. Mechanistically, HBXIP modulated METTL3 by inhibiting miRNA let-7g, which down-regulated the expression of METTL3 by targeting its 3'UTR. Strikingly, we found that METTL3 promoted the expression of HBXIP through m⁶A modification. Furthermore, overexpressed HBXIP could rescue the inhibited-proliferation and enhanced-apoptosis induced by silencing of METTL3 in breast cancer cells. Thus, we conclude that HBXIP up-regulates METTL3 by suppressing let-7g, in which METTL3 increased HBXIP expression forming a positive feedback loop of HBXIP/let-7g/METTL3/HBXIP, leading to accelerated cell proliferation in breast cancer. Our finding provides new insights into the mechanism of the mutual regulation between HBXIP and METTL3 in the progression of breast cancer.

Yes-associated protein: A novel molecular target for the diagnosis, treatment and prognosis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common type of malignant tumor. The early-diagnosis and treatment options for HCC are limited, which is primarily due to an incomplete understanding of the underlying molecular mechanisms of the disease. Yes-associated protein (YAP) overexpression promotes proliferation and phenotypic transformation of HCC cells. Recently, elucidating the molecular mechanisms of the Hippo/YAP signaling pathway and investigating the interactions between the signaling molecules, as a potential strategy for the treatment of HCC, has become an area of interest. The present review will discuss the role of YAP in HCC pathogenesis, and the significance of YAP in diagnosis, treatment and determining the prognosis.