Extracellular signal-regulated kinase 1 and 2 in cancer therapy: a focus on hepatocellular carcinoma

Network Pharmacology-Based Exploration on the Intervention of Qinghao Biejia Decoction on the Inflammation-Carcinoma Transformation Process of Chronic Liver Disease via MAPK and PI3k/AKT Pathway

Chronic liver disease(CLD) is a slow-developing and long-term disease that can cause serious damage to the liver. Thus far, it has been associated with viral hepatitis, non-alcoholic fatty liver disease(NAFLD), alcoholic liver disease(ALD), hepatic fibrosis(HF), liver cirrhosis (LC), and liver cancer. Qinghao Biejia Decoction (QBD) is a classic ancient Chinese herbal prescription with strong immune-enhancing, anti-inflammatory, and anti-tumor effects. In this study, we used a network pharmacology approach to investigate the molecular mechanisms of QBD in the inflammation-carcinoma transformation process of chronic liver disease. Two key drug targets, MAPK1 and PIK3CA, were screened using network pharmacology and molecular docking techniques, revealing dihydroartemisinin, artesunate, 12-O-Nicotinoylisolineolone, caffeic acid, and diincarvilone A as active ingredients involved in QBD mechanisms. The main signaling pathways involved were the PI3K-AKT signaling pathway and MAPK signaling pathway. In summary, our results indicated that QBD affects the inflammatory transformation of chronic liver disease through MAPK1 and PIK3CA and signaling pathways MAPK and PI3K/AKT. These data provide research direction for investigating the mechanisms underlying the inflammation-carcinoma transformation process in QBD for chronic liver disease.

Predicting response to platinum and non-platinum drugs through bioluminescence resonance energy transfer (BRET) based bio-molecular interactions in platinum resistant epithelial ovarian cancer

Therapy induced rewiring of signalling networks often lead to acquirement of platinum-resistance, thereby necessitating the use of non-platinum agents as second-line treatment particularly for epithelial ovarian cancer (EOC). A prior subject-specific assessment can guide the choice of optimal non-platinum agent/s and possible targeted therapeutic/s. Assessment of protein-protein interactions are superior to simple cytotoxicity assays to determine therapeutic efficacy and associated molecular responses. Utilizing improved PIP3-AKT and ERK1/2 activation Bioluminescence Resonance Energy Transfer (BRET) sensors, we report chemotherapy-induced ERK1/2 activation predominantly in cisplatin-paclitaxel resistant EOC cells and increased activation of both ERK1/2 and AKT in malignant ascites derived cancer cells from platinum-resistant patients but not from treatment-naive or platinum-sensitive relapse patients. Further, majority of the non-platinum drugs except irinotecan increased ERK1/2 activation in platinum-taxol resistant cells as observed by live-cell BRET assessment which were associated with p90RSK1/2 and BAD activation along with upregulation of multidrug transporter gene ABCC1 and cell survival genes like cyclin D1 and Bcl2. Interestingly, only irinotecan was able to sensitize these resistant cells. Altogether, this first report of BRET based sensing of molecular pathway activations in platinum resistant cell lines and patient's derived cancer cells highlight the clinical potential of BRET sensors in management of therapy resistant cancer.

Antiangiogenic effects of the chemopreventive agent tributyrin, a butyric acid prodrug, during the promotion phase of hepatocarcinogenesis

Agents that inhibit angiogenic factors may prevent the development of hepatocellular carcinoma (HCC). Thus, the objective of this study was to kinetically evaluate the antiangiogenic activity of tributyrin (TB), a butyric acid prodrug, in the promotion stage of hepatocarcinogenesis. For this purpose, the resistant hepatocyte (RH) model was used for induction of preneoplastic lesions in Wistar rats. During the promotion phase, the animals received TB or maltodextrin (MD) as control daily. The rats were killed at three time-points (P1, P2 and P3). Increased expression of Vegfa and Vegfr2 was observed during promotion phase of hepatocarcinogenesis, which was not reversed by TB treatment. However, TB treatment reduced the expression of cluster of differentiation (CD) 34-positive vessels at P3 and α-smooth muscle actin (α-SMA)-positive vessels at P2 compared with MD. Enhanced levels of hypoxia inducible factor-1α (HIF-1α) and phosphorylated extracellular signal-regulated kinases (pERK) were detected at P3 when compared with P1 and P2 in the MD treatment. TB treatment reduced the levels of HIF-1α and pERK at P3 relative to the MD control. Experiments with human umbilical vein endothelial cells (HUVEC) showed that sodium butyrate (NaBu) inhibited cell migration and tube formation, confirming the antiangiogenic activity of its prodrug TB. In conclusion, antiangiogenic activity of TB is an early event that already occurs in preneoplastic livers, reinforcing its potential chemopreventive effects against HCC.

microRNA-95 knockdown inhibits epithelial-mesenchymal transition and cancer stem cell phenotype in gastric cancer cells through MAPK pathway by upregulating DUSP5

This study investigated the role of microRNA-95 (miR-95) in gastric cancer (GC) and to elucidate the underlying mechanism. Initially, bioinformatic prediction was used to predict the differentially expressed genes and related miRNAs in GC. miR-95 and DUSP5 expression was altered in GC cell line (MGC803) to evaluate their respective effects on the epithelial-mesenchymal transition (EMT) process, cellular processes (cell proliferation, migration, invasion, cell cycle, and apoptosis), cancer stem cell (CSC) phenotype, as well as tumor growth ability. It was further predicted in bioinformatic prediction and verified in GC tissue and cell line experiments that miR-95 was highly expressed in GC. miR-95 negatively regulated DUSP5, which resulted in the MAPK pathway activation. Inhibited miR-95 or overexpressed DUSP5 was observed to inhibit the levels of CSC markers (CD133, CD44, ALDH1, and Lgr5), highlighting the inhibitory role in the CSC phenotype. More important, evidence was obtained demonstrating that miR-95 knockdown or DUSP5 upregulation exerted an inhibitory effect on the EMT process, cellular processes, and tumor growth. Together these results, miR-95 knockdown inhibited GC development via DUSP5-dependent MAPK pathway.

Extracellular-Signal Regulated Kinase: A Central Molecule Driving Epithelial-Mesenchymal Transition in Cancer

Epithelial-mesenchymal transition (EMT) is a reversible cellular process, characterized by changes in gene expression and activation of proteins, favoring the trans-differentiation of the epithelial phenotype to a mesenchymal phenotype. This process increases cell migration and invasion of tumor cells, progression of the cell cycle, and resistance to apoptosis and chemotherapy, all of which support tumor progression. One of the signaling pathways involved in tumor progression is the MAPK pathway. Within this family, the ERK subfamily of proteins is known for its contributions to EMT. The ERK subfamily is divided into typical (ERK 1/2/5), and atypical (ERK 3/4/7/8) members. These kinases are overexpressed and hyperactive in various types of cancer. They regulate diverse cellular processes such as proliferation, migration, metastasis, resistance to chemotherapy, and EMT. In this context, in vitro and in vivo assays, as well as studies in human patients, have shown that ERK favors the expression, function, and subcellular relocalization of various proteins that regulate EMT, thus promoting tumor progression. In this review, we discuss the mechanistic roles of the ERK subfamily members in EMT and tumor progression in diverse biological systems.

The effect of topical voriconazole on conjunctiva in rats as revealed by histopathology and immunohistochemistry

The aim of this study was to evaluate the effects of topical voriconazole with histopathological and immunohistochemical analysis of the conjunctiva in rats. Twenty-eight Sprague Dawley rats were divided into four groups as two study (S1, S2) and two control (C1, C2). Voriconazole was instilled four times daily to S1, S2 rats. Physiologic saline (0.9%) was instilled four times daily in C1 and C2 rats. S1 and C1 were followed in a dark room; S2 and C2 were held in a room with sunlight. Impression cytology was performed at 0, 15, 30, 45 and 60th d after instillations. After 2 months of treatment conjunctival tissue was removed for histological and immunohistochemical analysis. In impression cytology evaluation, there was no difference between S1 and S2. At 60 d the difference between S1 and C1 was significant. In other comparisons, there was no difference between S1 and C1, C2. The scores of S2 was higher than C1 and C2 for all comparisons except 15th day scores of S2 and C2. In study groups, epithelial and gland degeneration were higher in S2, but inflammation scores were similar. The comparison of immunreactivity of ERK, TGFβ and E-cadherin were different in the study groups than the control groups for all comparisons. In conclusion, voriconazole has side effects due to phototoxicity including squamous cell carcinoma. Clinicians should particularly be careful with the long-term use of topical voriconazole and should follow-up patients strictly in terms of ocular surface alterations.

CovaDOTS: In Silico Chemistry-Driven Tool to Design Covalent Inhibitors Using a Linking Strategy

We recently reported an integrated fragment-based optimization strategy called DOTS (Diversity Oriented Target-focused Synthesis) that combines automated virtual screening (VS) with semirobotized organic synthesis coupled to in vitro evaluation. The molecular modeling part consists of hit-to-lead chemistry, based on the growing paradigm. Here, we have extended the applicability of the DOTS strategy by adding new functionalities, allowing a generic chemistry-driven linking approach with a particular emphasis on covalent drugs. Indeed, the covalent mode of action can be described as a specific case of linking, where suitable linkers are sought to fuse a bound organic compound with a nucleophilic protein side chain. The proof of concept is established using three retrospective study cases in which known noncovalent inhibitors have been converted to covalent inhibitors. Our method is able to automatically design reference covalent inhibitors (and/or analogs) from an initial activated substructure and predict their binding mode. More importantly, the reference compounds are ranked high among several hundred putative adducts, demonstrating the utility of the approach to design covalent inhibitors.

Interleukin-10 negatively modulates extracellular signal-regulated kinases 1 and 2 in aorta from hypertensive mouse induced by angiotensin II infusion

The activation of extracellular signal-regulated kinase 1 and 2 (ERK 1/2) pathway promotes increased vascular contractility in angiotensin II (Ang II)-induced hypertensive mice. Interleukin-10 (IL-10) is an immune-regulatory cytokine with the ability to prevent vascular hypercontractility during hypertension. We hypothesized that IL-10 would downregulate vascular ERK 1/2 activation during Ang II-induced hypertension. Wild-type (WT) or IL-10 knockout (IL-10-/- ) mice received Ang II infusion (90 ηg.min) or vehicle (saline), via osmotic mini-pumps (0.25 μL/h for 14 days), whereas another WT group were infused with exogenous IL-10 (0.5 ηg/min, 14 days) simultaneously, or not, with Ang II. Aortic rings were mounted in a myograph, and concentration-response curves to phenylephrine were evaluated, in the presence or absence of ERK 1/2 inhibitor (PD98059, 10 μm, 40 min). Protein expression of vascular ERK 1/2 was determined by Western blot. Ang II infusion increased the maximal contractile response in both WT and IL-10-/- mice. Concomitant infusion of IL-10 and Ang II prevented hypercontractility in the vasculature. Exogenous IL-10 infusion prevented ERK 1/2 activation and hypercontractility, induced by Ang II. These findings suggest that IL-10 negatively modulates ERK 1/2 activation and prevents hypercontractility during Ang II-induced hypertension.

Pinocembrin-Enriched Fractions of Elytranthe parasitica (L.) Danser Modulates Apoptotic and MAPK Cellular Signaling in HepG2 Cells

Background:

Hepatocellular carcinoma (HCC) is the fifth leading cause of cáncer mortality. Elytranthe parasitica (L.) Danser (EP), a hemiparasitic plant (Loranthaceae) has potent anti-cancer properties.

Objective:

In the study, we investigated the effect of EP fractions on the expression of apoptosis and mitogenactivated protein kinase (MAPK) markers deregulated in HCC. Bioactivity fractionation was performed to isolate the phytochemical(s) exerting anti-tumor activity in HepG2 cells.

Method:

Anti-proliferative, clonogenic and anti-metastatic effects of EP fractions were examined in hepatocellular carcinoma cell line, HepG2 by Sulphorhodamine B, colony formation and scratch wound assays respectively in hepatocellular cell line, HepG2. The effects of EP fractions on key markers of apoptosis and MAPK signaling pathways were explored. </P><P> Key findings: EP bioactive fractions showed significant anti-tumor potential, reduced clonogenicity and considerably inhibited cell migration in HepG2 cells in vitro. The fractions augmented annexin V binding and induced apoptosis by causing cell cycle arrest at G2/M and S phase checkpoints. The fractions increased expression levels of p53, bad, cleaved PARP (Poly ADP ribose polymerase) and cleaved Caspase-3. Expression levels of phosphorylated ERK1/2 (Extracellular signal-regulated kinase) were downregulated. Pinocembrin-7-O-ß-D-glucoside and chrysin were isolated and characterized for the first time from Elytranthe parasitica (L.) Danser.

Conclusion:

Our findings reveal that EP fractions induced cell cycle arrest and triggered apoptosis in HepG2 cells by upregulating apoptosis and deactivating MAPK pathway. It signifies that pinocembrin glycoside and chrysin are bioactive phytochemicals contributing to the potent anti-hepatocarcinoma effects on HepG2 cells. Hence, bioactive EP fractions could be used as a therapeutic agent for effective HCC therapy.

Involvement of N-glycan in Multiple Receptor Tyrosine Kinases Targeted by Ling-Zhi-8 for Suppressing HCC413 Tumor Progression

The poor prognosis of hepatocellular carcinoma (HCC) is resulted from tumor metastasis. Signaling pathways triggered by deregulated receptor tyrosine kinases (RTKs) were the promising therapeutic targets for prevention of HCC progression. However, RTK-based target therapy using conventional kinase-based inhibitors was often hampered by resistances due to compensatory RTKs signaling. Herein, we report that Ling-Zhi-8 (LZ-8), a medicinal peptide from Ganoderma lucidium, was effective in suppressing cell migration of HCC413, by decreasing the amount and activity of various RTKs. These led to the suppression of downstream signaling including phosphorylated JNK, ERK involved in HCC progression. The capability of LZ-8 in targeting multiple RTKs was ascribed to its simultaneous binding to these RTKs. LZ-8 may bind on the N-linked glycan motif of RTKs that is required for their maturation and function. Notably, pretreatment of the N-glycan trimming enzyme PNGase or inhibitors of the mannosidase (N-glycosylation processing enzyme), kifunensine (KIF) and swainsonine (SWN), prevented LZ-8 binding on the aforementioned RTKs and rescued the downstream signaling and cell migration suppressed by LZ-8. Moreover, pretreatment of KIF prevented LZ-8 triggered suppression of tumor growth of HCC413. Our study suggested that a specific type of N-glycan is the potential target for LZ-8 to bind on multiple RTKs for suppressing HCC progression.

Small interfering RNA-mediated gene suppression as a therapeutic intervention in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the lethal and difficult-to-cure cancers worldwide. Owing to the late diagnosis and drug resistance of malignant hepatocytes, treatment of this cancer by conventional chemotherapy agents is challenging, and researchers are seeking new alternative treatment options to overcome therapy resistance in this neoplasm. RNA interference (RNAi) is a potent and specific approach in targeting gene expression and has emerged as a novel therapeutic tool for many diseases, including cancers. Small interfering RNA (siRNA) is a type of RNAi that is produced intracellularly from exogenous synthetic oligonucleotides and can selectively knock down target gene expression in a sequence-specific manner. Various factors play roles in the initiation and progression of HCC and provide multiple candidate targets for siRNA intervention. In addition, due to the liver's unique architecture and availability of some hepatic siRNA delivery methods, this organ has received much more attention as a target tissue for such oligonucleotide action. Recent advances in designing nanoparticle systems for the in vivo delivery of siRNAs have markedly enhanced the potency of siRNA-mediated gene silencing under clinical development for HCC therapy. The utility of siRNAs as anti-HCC agents is the subject of the current review. siRNA-based gene therapies could be one of the main feasible approaches for HCC therapy in the future.

The role of mitogen-activated protein kinase-extracellular receptor kinase pathway in female fertility outcomes: a focus on pituitary gonadotropins regulation

Mammalian reproduction systems are largely regulated by the secretion of two gonadotropins, that is, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). The main action of LH and FSH on the ovary is to stimulate secretion of estradiol and progesterone, which play an important role in the ovarian function and reproductive cycle control. FSH and LH secretions are strictly controlled by the gonadotropin-releasing hormone (GnRH), which is secreted from the hypothalamus into the pituitary vascular system. Maintaining normal secretion of LH and FSH is dependent on pulsatile secretion of GnRH. Extracellular signal-regulated kinase (ERK) proteins, as the main components of mitogen-activated protein kinase (MAPK) signaling pathways, are involved in the primary regulation of GnRH-stimulated transcription of the gonadotropins' α subunit in the pituitary cells. However, GnRH-stimulated expression of the β subunit has not yet been reported. Furthermore, GnRH-mediated stimulation of ERK1 and ERK2 leads to several important events such as cell proliferation and differentiation. In this review, we briefly introduce the relationship between ERK signaling and gonadotropin secretion, and its importance in female infertility.

Benzo(a)pyrene promotes Hep-G2 cell migration and invasion by upregulating phosphorylated extracellular signal-regulated kinase expression

Benzo(a)pyrene (BaP), a carcinogenic component of cigarette smoke, has been reported to activate extracellular signal-regulated kinase (ERK) in cancer cells. Furthermore, activated ERK is associated with liver cancer cell invasion and metastasis. Therefore, the aim of the present study was to investigate the potential role of phosphorylated (p)-ERK in BaP-induced Hep-G2 cell migration and invasion. An MTT assay was used to determine the effects of BaP treatment on Hep-G2 cell proliferation. Wound-healing and Transwell invasion assays were employed to assess the migration and invasion abilities of Hep-G2 cells. Western blot analysis was applied to detect the expression of proteins. The results of the present study demonstrated that BaP treatment was able to increase the level of p-ERK protein expression in Hep-G2 cells. BaP treatment promoted Hep-G2 cell migration and invasion. The ERK inhibitor, U0126, was able to block the migration and invasion abilities of Hep-G2 cells induced by BaP. The results of the present study demonstrated that BaP treatment promoted the migration and invasion of Hep-G2 cells by upregulating p-ERK expression.

Candidate Biomarkers for Oral Squamous Cell Carcinoma: Differential Expression of Oxidative Stress-Related Genes

Background:

Alteration in the biotransformation of exogenous compounds can result in production of reactive oxygen species (ROS), which can predispose cells to malignant transformation in the head and neck. This study aimed to evaluate the expression of genes involved in antioxidant metabolism in the oral squamous cell carcinoma (OSCC).

Methods:

The expression of eighty-four genes was evaluated in OSCC and non-tumor tissues by quantitative real-time polymerase chain reaction using the TaqMan Gene Expression Array. The biological mechanisms related to the differentially expressed genes were investigated using Gene – NCBI, KEGG, UNIPROT and REACTOME databases.

Results:

Twenty-one genes encoding enzymes involved in antioxidant metabolism were differentially expressed in the OSCC case. Four genes (ATOX1, PRDX4, PRNP, and SOD2) were up-regulated, and seventeen (ALOX12, CAT, CSDE1, DHCR24, DUOX1, DUOX2, EPHX2, GLRX2, GPX3, GSR, GSTZ1, MGST3, PRDX1, OXR1, OXSR1, SOD1, and SOD3) were down-regulated. We identified 14 possible novel biomarkers for OSCC. The differentially expressed genes appeared related to important biological processes involved in carcinogenesis, such as inflammation, angiogenesis, apoptosis, genomic instability, invasion, survival, and cell proliferation.

Conclusions:

Our study identified novel biomarkers which might warrant further investigation regarding OSCC pathogenesis since the altered expression in the genes can modulate biological processes related to oxidative stress and predispose cells to malignant transformation in the oral cavity.

The standardized Korean Red Ginseng extract and its ingredient ginsenoside Rg3 inhibit manifestation of breast cancer stem cell-like properties through modulation of self-renewal signaling

Background

The ginsenoside Rg3, one of active components of red ginseng, has chemopreventive and anticancer potential. Cancer stem cells retain self-renewal properties which account for cancer recurrence and resistance to anticancer therapy. In our present study, we investigated whether the standardized Korean Red Ginseng extract (RGE) and Rg3 could modulate the manifestation of breast cancer stem cell–like features through regulation of self-renewal activity.

Methods

The effects of RGE and Rg3 on the proportion of CD44^high/CD24^low cells, as representative characteristics of stem-like breast cancer cells, were determined by flow cytometry. The mammosphere formation assay was performed to assess self-renewal capacities of breast cancer cells. Aldehyde dehydrogenase activity of MCF-7 mammospheres was measured by the ALDEFLUOR assay. The expression levels of Sox-2, Bmi-1, and P-Akt and the nuclear localization of hypoxia inducible factor-1α in MCF-7 mammospheres were verified by immunoblot analysis.

Results

Both RGE and Rg3 decreased the viability of breast cancer cells and significantly reduced the populations of CD44^high/CD24^low in MDA-MB-231 cells. RGE and Rg3 treatment attenuated the expression of Sox-2 and Bmi-1 by inhibiting the nuclear localization of hypoxia inducible factor-1α in MCF-7 mammospheres. Suppression of the manifestation of breast cancer stem cell–like properties by Rg3 was mediated through the blockade of Akt-mediated self-renewal signaling.

Conclusion

This study suggests that Rg3 has a therapeutic potential targeting breast cancer stem cells.

p53-independent Noxa induction by cisplatin is regulated by ATF3/ATF4 in head and neck squamous cell carcinoma cells

The platinum‐based DNA damaging agent cisplatin is used as a standard therapy for locally advanced head and neck squamous cell carcinoma (HNSCC). However, the mechanisms underpinning the cytotoxic effects of this compound are not entirely elucidated. Cisplatin produces anticancer effects primarily via activation of the DNA damage response, followed by inducing BCL‐2 family dependent mitochondrial apoptosis. We have previously demonstrated that cisplatin induces the expression of proapoptotic BCL‐2 family protein, Noxa, that can bind to the prosurvival BCL‐2 family protein, MCL‐1, to inactivate its function and induce cell death. Here, we show that the upregulation of Noxa is critical for cisplatin‐induced apoptosis in p53‐null HNSCC cells. This induction is regulated at the transcriptional level. With a series of Noxa promoter‐luciferase reporter assays, we find that the CRE (cAMP response element) in the promoter is critical for the Noxa induction by cisplatin treatment. Among the CREB/ATF transcription factors, ATF3 and ATF4 are induced by cisplatin, and downregulation of ATF3 or ATF4 reduced cisplatin‐induced Noxa. ATF3 and ATF4 bind to and cooperatively activate the Noxa promoter. Furthermore, ERK1 is involved in cisplatin‐induced ATF4 and Noxa induction. In conclusion, ATF3 and ATF4 are important regulators that induce Noxa by cisplatin treatment in a p53‐independent manner.

Liposome-mediated RNA interference delivery against Erk1 and Erk2 does not equally promote chemosensitivity in human hepatocellular carcinoma cell line HepG2

BACKGROUND

Extracellular signal-regulated kinase (Erk)1 and Erk2 are central mediators of mitogen-activated protein kinase signaling pathway, which plays a key role in proliferation and chemoresistance of cancer cells. However, the effect of Erk1 and Erk2 in these processes may not be the same. The aim of this study was to investigate differential effect of Erk1 and Erk2 down-regulation on chemoresistance in human hepatocellular carcinoma (HCC) cells. Expression level and relative expression analysis in HepG2 cells were performed using RT-PCR and qRT-PCR, respectively. Phosphorylated-Erk1/2 and apoptosis analysis was performed by flow-cytometry (FCM) technique.

RESULTS

The results showed a higher expression level of Erk2 relative to Erk1 in HepG2 cells (P < 0.01). A significant decrease in phosphorylated-Erk1/2 and a compensational response was observed after Erk1 and/or Erk2 silencing using specific small interfering ribonucleic acids (siRNAs) (P < 0.01). Furthermore, 5-fluorouracil (5-FU) chemotherapy following siRNA-mediated knockdown lead to a significant enhancement of chemosensitivity with a higher rate of early apoptosis in Erk2 silencing relative to that of Erk1) + 9%, P < 0.01). 5-FU treatment after dual knockdown of Erk1/2 showed higher rate of early apoptosis relative to single Erk1 silencing (+9.25%, P < 0.01) and also higher rate of late apoptosis compared to single Erk1 and Erk2 silencing (+4.96% and +4.66%, P < 0.01).

CONCLUSION

Our data show that liposomal siRNA-mediated down-regulation of Erk1/2 can lead to potent chemosensitizing effects in HepG2 cells. Moreover, a higher chemosensitivity following Erk2 down-regulation than Erk1 down-regulation may be associated with the higher expression of Erk2 in human HCC.

14-3-3η is a novel growth-promoting and angiogenic factor in hepatocellular carcinoma

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. The continued search for novel therapeutic strategies for HCC is urgently required. In this study, we aimed to investigate the functions and clinical significance of 14-3-3η protein in HCC.

METHODS

Expressions of genes and proteins were determined by quantitative reverse transcription polymerase chain reaction, Western blot, and immunohistochemistry. Their functions were assessed by endothelial cell recruitment, tube formation, wound healing, flow cytometry, immunostaining, immunoprecipitation, and xenograft assay. A tissue microarray followed by univariate and multivariate analyses was performed to indicate the clinical significance.

RESULTS

In HCC specimens, overexpression of 14-3-3η was observed not only in tumors but also in intratumoral vessels. In HCC and vascular endothelial cells, 14-3-3η stimulated proliferation and angiogenesis, but attenuated the functions of sorafenib. Briefly, 14-3-3η facilitated the phosphorylation of extracellular signal-regulated kinase1/2 (ERK1/2). Then, by binding to the phosphorylated-ERK1/2 (p-ERK1/2), formed a functional positive feed-back loop. A xenograft model showed that, blockage of either 14-3-3η or ERK1/2 inhibited the tumor growth. Finally, tissue microarray analyses showed that overexpression of 14-3-3η, either in tumors or intratumoral vessels, contributed to the poor survival.

CONCLUSIONS

The 14-3-3η-ERK1/2 feedback loop played a characteristic growth-promoting role in HCC, not only in tumors but also in intratumoral vessels. Further, 14-3-3η could be a potential therapeutic target for HCC and a biomarker for predicting sorafenib treatment response.

LAY SUMMARY

Here we found that, 14-3-3η protein exhibited a characteristic growth-promoting effect in both tumor and intratumoral vessels of hepatocellular carcinoma by interacting with ERK1/2 signaling.