SIN1 promotes invasion and metastasis of hepatocellular carcinoma by facilitating epithelial-mesenchymal transition

Unmasking the tumourigenic role of SIN1/MAPKAP1 in the mTOR complex 2

BACKGROUND

Although the PI3K/AKT/mTOR pathway is one of the most altered pathways in human tumours, therapies targeting this pathway have shown numerous adverse effects due to positive feedback paradoxically activating upstream signaling nodes. The somewhat limited clinical efficacy of these inhibitors calls for the development of novel and more effective approaches for targeting the PI3K pathway for therapeutic benefit in cancer.

MAIN BODY

Recent studies have shown the central role of mTOR complex 2 (mTORC2) as a pro-tumourigenic factor of the PI3K/AKT/mTOR pathway in a number of cancers. SIN1/MAPKAP1 is a major partner of mTORC2, acting as a scaffold and responsible for the substrate specificity of the mTOR catalytic subunit. Its overexpression promotes the proliferation, invasion and metastasis of certain cancers whereas its inhibition decreases tumour growth in vitro and in vivo. It is also involved in epithelial-mesenchymal transition, stress response and lipogenesis. Moreover, the numerous interactions of SIN1 inside or outside mTORC2 connect it with other signaling pathways, which are often disrupted in human tumours such as Hippo, WNT, Notch and MAPK.

CONCLUSION

Therefore, SIN1's fundamental characteristics and numerous connexions with oncogenic pathways make it a particularly interesting therapeutic target. This review is an opportunity to highlight the tumourigenic role of SIN1 across many solid cancers and demonstrates the importance of targeting SIN1 with a specific therapy.

KIAA1217 Promotes Epithelial-Mesenchymal Transition and Hepatocellular Carcinoma Metastasis by Interacting with and Activating STAT3

The survival and prognosis of hepatocellular carcinoma (HCC) are poor, mainly due to metastasis. Therefore, insights into the molecular mechanisms underlying HCC invasion and metastasis are urgently needed to develop a more effective antimetastatic therapy. Here, we report that KIAA1217, a functionally unknown macromolecular protein, plays a crucial role in HCC metastasis. KIAA1217 expression was frequently upregulated in HCC cell lines and tissues, and high KIAA1217 expression was closely associated with shorter survival of patients with HCC. Overexpression and knockdown experiments revealed that KIAA1217 significantly promoted cell migration and invasion by inducing epithelial-mesenchymal transition (EMT) in vitro. Consistently, HCC cells overexpressing KIAA1217 exhibited markedly enhanced lung metastasis in vivo. Mechanistically, KIAA1217 enhanced EMT and accordingly promoted HCC metastasis by interacting with and activating JAK1/2 and STAT3. Interestingly, KIAA1217-activated p-STAT3 was retained in the cytoplasm instead of translocating into the nucleus, where p-STAT3 subsequently activated the Notch and Wnt/β-catenin pathways to facilitate EMT induction and HCC metastasis. Collectively, KIAA1217 may function as an adaptor protein or scaffold protein in the cytoplasm and coordinate multiple pathways to promote EMT-induced HCC metastasis, indicating its potential as a therapeutic target for curbing HCC metastasis.

High Expression of PAMR1 Predicts Favorable Prognosis and Inhibits Proliferation, Invasion, and Migration in Cervical Cancer

Peptidase domain containing associated with muscle regeneration 1 (PAMR1) is frequently lost in breast cancer samples and is considered as a tumor suppressor. The roles and mechanisms of PAMR1 in other types of cancers are still unclear. In our present study, we identified PAMR1 as an invasion-related regulator in cervical cancer. Public database and immunohistochemical (IHC) analysis showed that the expression level of PAMR1 in cervical cancer tissues was lower than that in normal cervix tissues and was negatively related to clinicopathologic features. The high expression of PAMR1 also predicted a better prognosis of cervical cancer patients. CCK8, Transwell, and wound-healing assays demonstrated that knockdown of PAMR1 facilitated the proliferation, migration, and invasion of cervical cancer cells. Additionally, gene set enrichment analysis (GSEA) showed a variety of cancer-related pathways potentially activated or suppressed by PAMR1. Moreover, we verified that PAMR1 inhibited MYC target and mTORC1 signaling pathways. In conclusion, our study revealed the suppressor role of PAMR1 in cervical cancer, providing a new insight into the molecular mechanism of cervical cancer progression.

The Roles of Post-Translational Modifications on mTOR Signaling

The mechanistic target of rapamycin (mTOR) is a master regulator of cell growth, proliferation, and metabolism by integrating various environmental inputs including growth factors, nutrients, and energy, among others. mTOR signaling has been demonstrated to control almost all fundamental cellular processes, such as nucleotide, protein and lipid synthesis, autophagy, and apoptosis. Over the past fifteen years, mapping the network of the mTOR pathway has dramatically advanced our understanding of its upstream and downstream signaling. Dysregulation of the mTOR pathway is frequently associated with a variety of human diseases, such as cancers, metabolic diseases, and cardiovascular and neurodegenerative disorders. Besides genetic alterations, aberrancies in post-translational modifications (PTMs) of the mTOR components are the major causes of the aberrant mTOR signaling in a number of pathologies. In this review, we summarize current understanding of PTMs-mediated regulation of mTOR signaling, and also update the progress on targeting the mTOR pathway and PTM-related enzymes for treatment of human diseases.

ADAM17 promotes the invasion of hepatocellular carcinoma via upregulation MMP21

Background

The upregulation of ADAM17 has been reported to be associated with invasion and metastasis in various tumors, however the molecular mechanism of ADAM17 in the progression of hepatocellular carcinoma (HCC) remain to be clarified. Human matrix metalloproteinase 21 (MMP21), the newest member of the MMP gene family, has been suggested to play an important role in embryogenesis and tumor progression. So far, nothing is known about the relationship between ADAM17 and MMP21.

Methods

In this study, the expression level of ADAM17 and MMP21 in HCC tissues was measured by immunohistochemistry. The Scratch wounding assay and Transwell were used to identify the invasion and metastasis ability. ELISA was used to evaluate the production of MMP21. Coimmunoprecipitation experiments demonstrated a direct association between ADAM17 and MMP21. HPLC was used to confirmed that ADAM17 participated in the maturation of MMP21.

Results

Our present data indicated that ADAM17 and MMP21 was significantly upregulated in human HCC tissues. Knockdown of ADAM17 in HCC inhibited cell invasion and metastasis. Moreover, ADAM17 regulates the secretion and expression of MMP21. Furthermore we discovered a direct association between ADAM17 and MMP21, and we also found MMP21 prodomain could be cleaved by ADAM17.

Conclusion

Our data suggest that ADAM17 plays an important role in the development of HCC invasion and metastasis and this function may be implement by MMP21.

Study on the hepatocellular carcinoma model with metastasis

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death around the world due to advanced clinical stage at diagnosis, high incidence of recurrence and metastasis after surgical treatment. It is in urgent need to create appropriate animal models to explore the mechanism, patterns, risk factors, and therapeutic strategies of HCC metastasis and recurrence. However, most of the established models lack the phenotype of invasion and metastasis in patient, or have unstable phenotype. To establish HCC models with stable metastasis phenotype requires profound understanding in cancer metastasis biology and scientific methodology. Over the past 3 decades, HCC models with stable metastasis have been extensively studied. This paper reviewed the history and development of HCC animal models and cell models, focusing on the screening and maintaining of metastatic potential and phenotype. In-depth studies using these models vastly promote the understanding of cellular and molecular mechanisms and development of therapeutic strategies on HCC metastasis.

G-Protein-Coupled Estrogen Receptor 1 Promotes Gender Disparities in Hepatocellular Carcinoma via Modulation of SIN1 and mTOR Complex 2 Activity

Due to its intricate heterogeneity and limited treatment, hepatocellular carcinoma (HCC) has been considered a major cause of cancer-related mortality worldwide. Increasing evidence indicates that G-protein-coupled estrogen receptor 1 (GPER1) can promote estrogen-dependent hepatocellular proliferation by activating AKT signaling. The mTOR complex 2 (mTORC2), whose integrity and activity are modulated by its subunit Sin1, controls the activation of AKT by phosphorylation at position S473. In this study, we investigate the modulation of Sin1 and how estrogen signaling may influence the mTORC2-AKT cascade in HCC cells and a DEN-induced mouse model. We have found that estradiol-dependent Sin1 expression is transcriptionally modulated by GPER1 as well as ERα. GPER1 is able to regulate Sin1 stability via nuclear translocation, therefore increasing Sin1-mTORC2-AKT activation. Moreover, Sin1 interacts with ERα and further enhances its transcriptional activity. Sin1 is highly expressed in acute liver injury and in cases of HCC harboring high expression of GPER1 and constitutive activation of mTORC2-AKT signaling. GPER1 inhibition using the antagonist G-15 reverses DEN-induced acute liver injury by suppressing Sin1 expression and mTORC2-AKT activation. Notably, SIN1 expression varies between male and female mice in the context of both liver injury and liver cancer. In addition, high SIN1 expression is predictive of good prognosis in both male and female patients with HCC who are free from hepatitis virus infection and who report low alcohol consumption. Hence, here we demonstrate that Sin1 can be regulated by GPER1 both through nongenomic and indirect genomic signaling. IMPLICATIONS: This study suggests that Sin1 may be a novel HCC biomarker which is gender-dependent and sensitive to particular risk factor.

STAT3-mediated MLST8 gene expression regulates cap-dependent translation in cancer cells

Signal transducer and activator of transcription 3 (STAT3) regulates cell growth, cell survival, angiogenesis, metastasis of cancer cells, and cancer immune evasion by regulating gene expression as a transcription factor. However, the effect of STAT3 on translation is almost unknown. We demonstrated that STAT3 acts as a trans‐acting factor for MLST8 gene expression and the protein level of mLST8, a core component of mechanistic target of rapamycin complex 1 and 2 (mTORC1/2), positively regulates the mTORC1/2 downstream pathways. Suppression of STAT3 by siRNA attenuated 4E‐BP1 phosphorylation, cap‐dependent translation, and cell proliferation in a variety of cancer cells. In HCT116 cells, STAT3 knockdown‐induced decreases in 4E‐BP1 and AKT phosphorylation levels were further attenuated by MLST8 knockdown or recovered by mLST8 overexpression. STAT3 knockdown‐induced G2/M phase arrest was partially restored by co‐knockdown of 4EBP1, and the attenuation of cell proliferation was enhanced by the expression of an mTORC1‐mediated phosphorylation‐defective mutant of 4E‐BP1. ChIP and promoter mapping using a luciferase reporter assay showed that the −951 to −894 bp of MLST8 promoter seems to include STAT3‐binding site. Overall, these results suggest that STAT3‐driven MLST8 gene expression regulates cap‐dependent translation through 4E‐BP1 phosphorylation in cancer cells.

Sin1 promotes proliferation and invasion of prostate cancer cells by modulating mTORC2-AKT and AR signaling cascades

AIMS

Prostate cancer (PCa) is the most common type of cancer and a major cause of death in men worldwide. Aberrant Androgen receptor (AR) and PI3K-AKT signaling are very frequent in PCa patients and, therefore, considered as therapeutic targets in the clinic. Sin1 is an essential component of mTORC2 complex, which determines full AKT activation and PCa development in PTEN^-/- mice. Here we examined the role of Sin1 in human PCa cell lines and respective tumor samples.

MAIN METHODS

Western blotting and immunohistochemistry (IHC) were performed to analyze the expression of Sin1-mTORC2-AKT related proteins in human PCa cells, as well as prostate tumors and normal tissue counterparts. Cell viability and invasion assays were also pursued in the presence or not of Sin1 in PCa cells. Immunoprecipitation assays were additionally carried out to examine the interaction of Sin1 with AR.

KEY FINDINGS

We have presently demonstrated that high levels of Sin1 expression in human PCa tissues correlate with cancer progression. Sin1-mediated cell proliferation and invasion of PCa cells occurs by regulating mTORC2-AKT signaling, epithelial-mesenchymal transition and matrix metalloproteinases. Moreover, androgens are able to induce Sin1 expression, which is further translocated to the nucleus of PCa cells. Finally, Sin1 interacts with AR to suppress its transcriptional activity.

SIGNIFICANCE

Taken together, these data indicate that both Sin1-mediated mTORC2-AKT signaling and Sin1-AR interaction regulate PCa development. Hence, Sin1 may be considered a novel biomarker of PCa progression.

Genetic Predisposition to Glioma Mediated by a MAPKAP1 Enhancer Variant

Mitogen-activated protein kinase-associated protein 1 (MAPKAP1) is a unique component of the mechanistic target of rapamycin (MTOR) pathway which plays a pivotal role in carcinogenesis. The role of enhancer variant in carcinogenesis receives increased attentions. However, the significance of enhancer variants of MAPKAP1 in glioma has not yet been investigated. The associations of enhancer variants of MAPKAP1 with glioma susceptibility were evaluated in a cohort of 400 glioma patients and 651 controls. The function of glioma susceptibility locus was examined by a set of biochemical assays. We found that an enhancer variant of MAPKAP1 rs473426 was associated with a significantly increased risk of glioma in a dominant manner (OR 1.53, 95% CI 1.13-2.06; P = 0.006). The association for rs1339499 located in the same enhancer approached the borderline of significance after multiple testing correction (OR 0.74, 95% CI 0.56-0.98; P = 0.037). Furthermore, cumulative associations of rs473426 and rs1339499 with glioma risk were observed (P = 0.011). Functional analyses showed that the risk allele rs473426 C downregulated the regulatory activity of enhancer by reducing the binding affinity of a transcriptional activator NFΙC, which resulted in lower gene expression both in vitro and in vivo. These results demonstrate for the first time that enhancer variant of MAPKAP1 confers susceptibility to glioma by downregulation of MAPKAP1 expression, and provide further evidence highlighting MAPKAP1 as a cancer suppressor in glioma carcinogenesis.

Sin1-mediated mTOR signaling in cell growth, metabolism and immune response

The mammalian target of rapamycin (mTOR) is an evolutionarily conserved Ser/Thr protein kinase with essential cellular function via processing various extracellular and intracellular inputs. Two distinct multi-protein mTOR complexes (mTORC), mTORC1 and mTORC2, have been identified and well characterized in eukaryotic cells from yeast to human. Sin1, which stands for Sty1/Spc1-interacting protein1, also known as mitogen-activated protein kinase (MAPK) associated protein (MAPKAP)1, is an evolutionarily conserved adaptor protein. Mammalian Sin1 interacts with many cellular proteins, but it has been widely studied as an essential component of mTORC2, and it is crucial not only for the assembly of mTORC2 but also for the regulation of its substrate specificity. In this review, we summarize our current knowledge of the structure and functions of Sin1, focusing specifically on its protein interaction network and its roles in the mTOR pathway that could account for various cellular functions of mTOR in growth, metabolism, immunity and cancer.

Wnt7a, frequently silenced by CpG methylation, inhibits tumor growth and metastasis via suppressing epithelial-mesenchymal transition in gastric cancer

Wnt7a is a member of the Wnt family and has been reported to be involved in the carcinogenesis and progression of many types of human cancer. However, little is known about Wnt7a expression and function in gastric cancer (GC). In the present study, Wnt7a expression in GC tissues and cells was investigated, the correlation between Wnt7a expression and the prognosis was also examined. The effects of Wnt7a on proliferation, invasion, and metastasis were evaluated in vitro and in vivo. Furthermore, the expression of epithelial-mesenchymal transition (EMT) markers and hypermethylation of the Wnt7a promoter were both detected. Wnt7a was downregulated in GC and its expression was associated with poor prognosis of patients with GC. Moreover, upregulation of Wnt7a significantly suppressed the growth, invasion, and metastasis abilities of GC cells in vitro and in vivo. Mechanistically, Wnt7a was found to inhibit EMT process of GC cells. In addition, the reducing expression of Wnt7a was due to methylation of 5'-CpG island within the promoter. Furthermore, the tumor suppressor role of Wnt7a is independent of canonical Wnt/β-catenin signaling in GC cells. In conclusion, our findings demonstrated that Wnt7a could be used as a potential diagnostic marker and target for GC management.

Nitidine Chloride Inhibits SIN1 Expression in Osteosarcoma Cells

Nitidine chloride (NC) has been demonstrated to exert a tumor-suppressive function in various types of human cancers. However, the detailed mechanism of NC-mediated anti-tumor effects remains elusive. It has been reported that SIN1, a component of mTORC2 (mammalian target of rapamycin complex C2), plays an oncogenic role in a variety of human cancers. Therefore, the inhibition of SIN1 could be useful for the treatment of human cancers. In this study, we explored whether NC triggered an anti-cancer function via the inhibition of SIN1 in osteosarcoma (OS) cells. An MTT assay was performed to measure the effect of NC on the cell growth of osteosarcoma cells, and flow cytometry was used to detect the apoptotic rate of the cells after NC treatment. The expression of SIN1 was detected by western blotting. Wound-healing assay and Transwell chamber invasion assay were conducted to analyze the motility of osteosarcoma cells following NC exposure. We found that exposure to NC led to the inhibition of cell growth, migration, and invasion and the induction of apoptosis. Mechanistically, we found that NC inhibited the expression of SIN1 in osteosarcoma cells. Overexpression of SIN1 abrogated the inhibition of cell growth and motility induced by NC in osteosarcoma cells. Our results indicate that NC exhibits its tumor-suppressive activity via the inhibition of SIN1 in osteosarcoma cells, suggesting that NC could be a potential inhibitor of SIN1 in osteosarcoma.

c-Jun N-terminal kinase (JNK)-mediated induction of mSin1 expression and mTORC2 activation in mesenchymal cells during fibrosis

Mammalian target of rapamycin complex 2 (mTORC2) has been shown to regulate mTORC1/4E-BP1/eIF4E signaling and collagen I expression in mesenchymal cells (MCs) during fibrotic activation. Here we investigated the regulation of the mTORC2 binding partner mammalian stress-activated protein kinase-interacting protein 1 (mSin1) in MCs derived from human lung allografts and identified a novel role for mSin1 during fibrosis. mSin1 was identified as a common downstream target of key fibrotic pathways, and its expression was increased in MCs in response to pro-fibrotic mediators: lysophosphatidic acid (LPA), transforming growth factor β, and interleukin 13. Fibrotic MCs had higher mSin1 protein levels than nonfibrotic MCs, and siRNA-mediated silencing of mSIN1 inhibited collagen I expression and mTORC1/2 activity in these cells. Autocrine LPA signaling contributed to constitutive up-regulation of mSin1 in fibrotic MCs, and mSin1 was decreased because of LPA receptor 1 siRNA treatment. We identified c-Jun N-terminal kinase (JNK) as a key intermediary in mSin1 up-regulation by the pro-fibrotic mediators, as pharmacological and siRNA-mediated inhibition of JNK prevented the LPA-induced mSin1 increase. Proteasomal inhibition rescued mSin1 levels after JNK inhibition in LPA-treated MCs, and the decrease in mSin1 ubiquitination in response to LPA was counteracted by JNK inhibitors. Constitutive JNK1 overexpression induced mSin1 expression and could drive mTORC2 and mTORC1 activation and collagen I expression in nonfibrotic MCs, effects that were reversed by siRNA-mediated mSIN1 silencing. These results indicate that LPA stabilizes mSin1 protein expression via JNK signaling by blocking its proteasomal degradation and identify the LPA/JNK/mSin1/mTORC/collagen I pathway as critical for fibrotic activation of MCs.

IL-6/STAT3 pathway intermediates M1/M2 macrophage polarization during the development of hepatocellular carcinoma

Human cancers, including hepatocellular carcinoma (HCC), are characterized by a high degree of drug resistance in chemotherapy. However, the underlying molecular mechanism remains unknown. To the role of interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in the regulation of macrophage polarization, M1-type and M2-type macrophages were separately induced using lipopolysaccharide and interleukin-4 (IL-4), and we found that the IL-6/STAT3 signaling pathway was inhibited in M1-type macrophages but activated in M2-type macrophages. After anti-IL-6-treated macrophages were separately induced by lipopolysaccharide and IL-4, we found that the inhibition of IL-6/STAT3 signaling pathway turned macrophages into M1-type. Co-culture with M1-type macrophages reduced HCC cell viability, proliferation, invasion, migration, drug resistance, but increased apoptosis. Co-culture with M2-type macrophages yielded reciprocal results. The inhibition of IL-6/STAT3 signaling pathway mediated by anti-IL6 was shown to significantly enhance the effects of M1-type macrophages on HCC cells and rescue HCC cells from co-culture with M2-type macrophages. Tumor xenografts of co-cultured HCC cells were established in nude mice and the results showed that the inhibition of IL-6/STAT3 signaling pathway mediated by anti-IL6 was found to reduce tumor formation of HCC cells co-cultured with M1- or M2-type macrophages and lung metastases. The current study reveals a novel mechanism of IL-6/STAT3 signaling pathway in the regulation of macrophage polarization, thus contributing to HCC metastasis and drug resistance in chemotherapy.

YMO1 suppresses invasion and metastasis by inhibiting RhoC signaling and predicts favorable prognosis in hepatocellular carcinoma

Previous studies have shown that 4.1 proteins, which are deregulated in many cancers, contribute to cell adhesion and motility. Yurt/Mosaic eyes-like 1 (YMO1) is a member of 4.1 protein family but it is unclear whether YMO1 plays a role in tumor invasion. This study aimed to investigate the effects of YMO1 on hepatocellular carcinoma (HCC) and attempted to elucidate the underlying molecular mechanisms. YMO1 expression in HCC tissues and its correlation with clinicopathological features and postoperative prognosis was analyzed. The results showed that YMO1 was down-regulated in the highly metastatic HCC cell line and in human tumor tissues. Underexpression of YMO1 indicated poor prognosis of HCC patients. Restoration of YMO1 expression caused a significant decrease in cell migration and invasiveness in vitro. In vivo study showed that YMO1 reduced liver tumor invasion and metastasis in xenograft mice. YMO1 directly inhibited RhoC activation. YMO1 expression in HCC was regulated by PAX5. Analysis of YMO1 expression levels in human HCC patients revealed a significant correlation of YMO1 expression with PAX5 and RhoC. Our findings revealed that YMO1 predicts favorable prognosis and the data suggest that YMO1 suppresses tumor invasion and metastasis by inhibiting RhoC activity.

JARID2 promotes invasion and metastasis of hepatocellular carcinoma by facilitating epithelial-mesenchymal transition through PTEN/AKT signaling

JARID2 is crucial for maintenance of pluripotency and differentiation of embryonic stem cells. However, little is known about the role of JARID2 in metastasis of hepatocellular carcinoma (HCC). This study found that JARID2 expression was significantly higher in HCC tissues than that in adjacent non-tumor liver tissues (ANLTs), and its expression level correlated with HCC metastasis. High JARID2 expression was significantly correlated with multiple tumor nodules, high Edmondson-Steiner grade, microvascular invasion, advanced TNM stage and advanced BCLC stage (all P < 0.05) and indicated poor prognosis of HCC in training and validation cohorts (all P < 0.05) totaling 182 patients. High JARID2 expression was an independent and significant risk factor for disease-free survival (DFS; P = 0.017) and overall survival (OS; P = 0.041) after curative liver resection in training cohort, and also validated as an independent and significant risk factor for DFS (P = 0.033) and OS (P = 0.031) in validation cohort. Moreover, down-regulation of JARID2 dramatically inhibited HCC cell migration, invasion, proliferation in vitro and metastasis in vivo, whereas overexpression of JARID2 significantly increased migration, invasion, proliferation in vitro and metastasis in vivo. Mechanistically, the data showed that JARID2 exerted its function by repressing PTEN expression through increasing H3K27 trimethylation (H3K27me3) at PTEN promoter region, which subsequently resulted in activation of protein kinase B (AKT) and enhanced epithelial-mesenchymal transition (EMT). In conclusion, this study revealed that JARID2 promotes invasion and metastasis of HCC by facilitating EMT through PTEN/AKT signaling.

APPL1 promotes the migration of gastric cancer cells by regulating Akt2 phosphorylation

As a multifunctional adaptor protein, APPL1 (adaptor protein containing pleckstrin homology domain, phosphotyrosine binding domain and a leucine zipper motif 1) is overexpressed in many cancers, and has been implicated in tumorigenesis and tumor progression. The present study investigated the expression of APPL1 in gastric carcinoma and the function in regulating cell migration. We investigated the expression of APPL1 in gastric carcinoma based upon The Cancer Genome Atlas (TCGA) database. The expression of APPL1 in collected gastric carcinoma tissues and cultured cells was measured by qRT-PCR and western blot analysis. Transwell assay and wound healing assay were used to analyze the effects of APPL1 on tumor cell migration. The statistical results based upon TCGA database showed significantly higher expression of APPL1 in gastric carcinoma compared to adjacent normal tissues, and we confirmed these findings by measuring APPL1 expression in collected gastric carcinoma tissues and cultured cells. The results of transwell assay and wound healing assay showed that when APPL1 was silenced by siRNA, cell migration was inhibited and overexpression of APPL1 promoted migration. Western blot results demonstrated that changes in several mesenchymal markers were consistent with the observed reduction or enhancement of cell migration. Importantly, the expression of APPL1 significantly affected the phosphorylation of Akt2. In addition, MMP2 and MMP9, downstream effectors of Akt2 changed accordingly, which is a critical requirement for Akt2-mediated cell migration. The results demonstrate an important new function of APPL1 in regulating cell migration through a mechanism that depends on Akt2 phosphorylation.

Sorcin Predicts Poor Prognosis and Promotes Metastasis by Facilitating Epithelial-mesenchymal Transition in Hepatocellular Carcinoma

Metastasis-associated recurrence is the main cause for the poor prognosis of hepatocellular carcinoma (HCC). However, the detailed molecular mechanisms underlying HCC metastasis remain elusive. Though some data indicated the oncogenic role of Sorcin in tumors, the prognostic value and biological role of Sorcin in HCC is still unknown. In this study, it demonstrated that Sorcin expression levels were significantly upregulated in HCC tumor tissues compared with matched adjacent nontumorous liver tissues and normal liver tissues, and such expression level correlated with HCC metastasis. High Sorcin expression was significantly correlated with aggressive clinicopathological characteristics such as multiple tumor nodules, high Edmondson-Steiner grade, microvascular invasion, advanced TNM stage and advanced BCLC stage (all P < 0.05). HCC patients with high Sorcin expression had both shorter survival and higher recurrence than those with low Sorcin expression (all P < 0.05). Sorcin expression was an independent and significant risk factor for survival and recurrence of HCC patients. Results of functional experiments showed that Sorcin could promote HCC cell proliferation, migration, and invasion in vitro, and facilitate HCC growth and metastasis in vivo. Mechanistically, Sorcin exerted its role by activating extracellular signal-regulated kinase (ERK) pathway and promoted metastasis by facilitating epithelial-mesenchymal transition (EMT) in HCC.

Tumor suppressor Pdcd4 attenuates Sin1 translation to inhibit invasion in colon carcinoma

Programmed cell death 4 (Pdcd4), a tumor invasion suppressor, is frequently down-regulated in colorectal cancer and other cancers. In this study, we find that loss of Pdcd4 increases the activity of mammalian target of rapamycin complex 2 (mTORC2) and thereby upregulates Snail expression. Examining the components of mTORC2 showed that Pdcd4 knockdown increased the protein but not mRNA level of stress-activated-protein kinase interacting protein 1 (Sin1), which resulted from enhanced Sin1 translation. To understand how Pdcd4 regulates Sin1 translation, the SIN1 5’ untranslated region (5’UTR) was fused with luciferase reporter and named as 5’Sin1-Luc. Pdcd4 knockdown/knockout significantly increased the translation of 5’Sin1-Luc but not the control luciferase without the SIN1 5’UTR, suggesting that Sin1 5’UTR is necessary for Pdcd4 to inhibit Sin1 translation. Ectopic expression of wild type Pdcd4 and Pdcd4(157–469), a deletion mutant that binds to translation initiation factor 4A (eIF4A), sufficiently inhibited Sin1 translation, and thus suppressed mTORC2 kinase activity and invasion in colon tumor cells. By contrast, Pdcd4(157–469)(D253A,D418A), a mutant that does not bind to eIF4A, failed to inhibit Sin1 translation, and consequently failed to repress mTORC2 activity and invasion. In addition, directly inhibiting eIF4A with silvestrol significantly suppressed Sin1 translation and attenuated invasion. These results indicate that Pdcd4-inhibited Sin1 translation is through suppressing eIF4A, and functionally important for suppression of mTORC2 activity and invasion. Moreover, in colorectal cancer tissues, the Sin1 protein but not mRNA was significantly up-regulated while Pdcd4 protein was down-regulated, suggesting that loss of Pdcd4 might correlate with Sin1 protein level but not mRNA level in colorectal cancer patients. Taken together, our work reveals a novel mechanism by which Pdcd4 inhibits Sin1 translation to attenuatemTORC2 activity and thereby suppresses invasion.

Overexpression of TMPRSS4 promotes tumor proliferation and aggressiveness in breast cancer

Transmembrane protease serine 4 (TMPRSS4) is a novel type II transmembrane serine protease that is overexpressed in various types of human cancers and has an important function in cancer progression. However, there is a paucity of data available regarding the biological effects of TMPRSS4 on breast cancer (BC) cells and the underlying mechanisms. In this study, expression of TMPRSS4 in BC tissues was detected by immunohistochemistry. The relationship between TMPRSS4 expression and clinicopathological characteristics as well as prognosis was evaluated. The effects of TMPRSS4 on cell proliferation, migration and invasion were investigated in BC cell lines in vitro. Additionally, RT-qPCR and western blot analysis were used to determine the expressions of epithelial-mesenchymal transition (EMT) biomarkers and TMPRSS4 in BC cell lines. We found that TMPRSS4 was overexpressed in BC tissues and its expression level was closely correlated with tumor size, histological grade, lymph node metastasis, clinical stage as well as poor survival (all P<0.05) and could be recognized as an independent prognostic factor for BC patients. Overexpression of TMPRSS4 promoted the proliferation, migration and invasion of BC cells in vitro. Moreover, TMPRSS4 knockdown significantly enhanced the expression of E-cadherin and claudin-1 and inhibited the expression of vimentin and Slug, indicating suppression of EMT. Our results suggest that TMPRSS4 plays a crucial role in the progression of BC. Moreover, TMPRSS4 overexpression promoted the proliferation, invasion and migration of BC cells by possibly inducing EMT. To conclude, TMPRSS4 may be a potential therapeutic target for cancer treatment.

Epigenetic activation of SIN1 promotes NSCLC cell proliferation and metastasis by affecting the epithelial-mesenchymal transition

Stress-activated protein kinase (SAPK) interacting protein 1 (SIN1) is an essential component of mTORC2. Previous studies have shown that SIN1 is a key regulator of Akt pathway which plays an important role in various pathological conditions including cancer. While its effects and mechanisms on the progression of NSCLC remain unknown. In this study, we report that SIN1 is able to promote the growth and migration of NSCLC cells both in vitro and in vivo. Overexpression of SIN1 promoted A549 and H1299 cells proliferation by both MTT and colony formation assays. Consistently, knockdown of SIN1 inhibited the proliferation of these cells. In transwell assay, overexpression of SIN1 increased the migration of A549 and H1299 cells, while SIN1 knockdown reduced their migration. In a tumor xenograft model, overexpression of SIN1 promoted tumor growth of A549 cells in vivo, while SIN1 knockdown suppresses the tumor growth. We also found a mechanistic link between SIN1 and H3K4me3, H3K4me3 is involved in SIN1 upregulation. Moreover, SIN1 can significantly promote the in vitro migration and invasion of NSCLC cells via induction epithelial mesenchymal transition (EMT) process, which subsequently leads to transcriptional downregulation of epithelial marker E-cadherin and upregulation of mesenchymal markers N-cadherin and Vimentin expression. Together, our results reveal that SIN1 plays an important role in NSCLC and SIN1 is a potential biomarker and a promising target in the treatment of NSCLC.

SIN1 promotes the proliferation and migration of breast cancer cells by Akt activation

Stress-activated protein kinase (SAPK) interacting protein 1 (SIN1) is an essential TORC2 component and a key regulator of Akt pathway that plays an important role in various pathological conditions including cancer. Whereas its functional role in breast cancer has not been well characterized. In the present study, SIN1 is associated with the progression and survival of breast cancer patients, as well as human breast cancer cell proliferation and migration. SIN1 mRNA level was significantly up-regulated in human breast cancer samples compared with their corresponding paracancerous histological normal tissues. Furthermore, the expression levels of SIN1 were also increased in three human breast cancer cell lines compared with human breast epithelial cell MCF10A. Overexpression of SIN1 promoted cell proliferation, colony formation and migration of breast cancer cells. Knockdown of SIN1 in MDA-MB-468 cells inhibited cell proliferation, colony formation and migration. In addition, SIN1 overexpression increased phosphorylation of Akt and knockdown of SIN1 inhibited phosphorylation of Akt in MDA-MB-468 cells. In a tumour xenograft model, overexpression of SIN1 promoted tumour growth of MDA-MB-468 cells in vivo, whereas SIN1 knockdown inhibits the tumour growth. Taken together, our results reveal that SIN1 plays an important role in breast cancer and SIN1 is a potential biomarker and a promising target in the treatment of breast cancer.

Impact of Tight Junction Protein ZO-1 and TWIST Expression on Postoperative Survival of Patients with Hepatocellular Carcinoma

BACKGROUND

Epithelial-mesenchymal transition (EMT) is considered to play a critical role in cancer progression and metastasis. However, the impact of EMT on the prognosis of hepatocellular carcinoma (HCC) is still elusive. In this study, we examined the relationship between the expression of EMT markers and recurrence-free survival (RFS) and overall survival (OS) in HCC patients after hepatic resection.

SUMMARY

The mRNA expression of 15 genes related to EMT was assessed by quantitative real-time polymerase chain reaction in cancerous tissues from 72 patients who underwent hepatic resection of HCC between January 2005 and December 2010 at our hospital. The upregulation of TWIST and the downregulation of tight junction protein ZO-1 (TJP1) were significantly associated with shorter RFS as well as OS. Increased levels of TWIST and decreased levels of TJP1 should be predictive markers for poor prognosis in patients with HCC after hepatectomy; those could serve as potential biomarkers for the treatment of HCC. Key Messages: A low level of TJP1 and high level of TWIST expression were prognostic factors predicting HCC after hepatic resection.

Actin-like 6A predicts poor prognosis of hepatocellular carcinoma and promotes metastasis and epithelial-mesenchymal transition

Hepatocellular carcinoma (HCC) is one of the most lethal cancers worldwide because of metastasis. Epithelial-mesenchymal transition (EMT) is widely considered to be crucial to the invasion-metastasis cascade during cancer progression. Actin-like 6A (ACTL6A) is initially verified important for cell proliferation, differentiation, and migration. In this study, we find that ACTL6A plays an essential role in metastasis and EMT of HCC. ACTL6A expression is up-regulated in HCC cells and tissues. A high level of ACTL6A in HCCs is correlated with aggressive clinicopathological features and is an independent poor prognostic factor for overall and disease-free survival of HCC patients. Ectopic expression of ACTL6A markedly promotes HCC cells migration, invasion, as well as EMT in vitro and promotes tumor growth and metastasis in the mouse xenograft model. Opposite results are observed when ACTL6A is knocked down. Mechanistically, ACTL6A promotes metastasis and EMT through activating Notch signaling. ACTL6A knockdown has the equal blockage effect as the Notch signaling inhibitor, N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butylester, in HCC cells. Further studies indicate that ACTL6A might manipulate SRY (sex determining region Y)-box 2 (SOX2) expression and then activate Notch1 signaling.

CONCLUSIONS

ACTL6A promotes metastasis and EMT by SOX2/Notch1 signaling, indicating a prognostic biomarker candidate and a potential therapeutic target for HCC.

TMPRSS4 facilitates epithelial-mesenchymal transition of hepatocellular carcinoma and is a predictive marker for poor prognosis of patients after curative resection

TMPRSS4 (Transmembrane protease serine 4) is up-regulated in a broad spectrum of cancers. However, little is known about the biological effects of TMPRSS4 on hepatocellular carcinoma (HCC) and the related mechanisms. In the present study, we found that overexpression of TMPRSS4 significantly promoted the invasion, migration, adhesion and metastasis of HCC. Further more, TMPRSS4 induced EMT of HCC, which was mediated via snail and slug as a result of Raf/MEK/ERK1/2 activation, and inhibition of ERK1/2 activation by its inhibitor was associated with reduced cell invasion and reversion of EMT. In addition, we demonstrated that TMPRSS4 remarkably suppressed the expression of RECK, an inhibitor of angiogenesis, and drastically induced tumor angiogenesis and growth. More important, in clinical HCC specimens, TMPRSS4 expression was significantly correlated with tumor staging and was inversely correlated with E-cadherin and RECKS expression. Expression of TMPRSS4 is significantly associated with HCC progression and is an independent prognostic factor for postoperative worse survival and recurrence. In conclusion, TMPRSS4 functions as a positive regulator of Raf/MEK/ERK1/2 pathway and promotes HCC progression by inducing EMT and angiogenesis. The increase of TMPRSS4 expression may be a key event for HCC progression and may be regarded as a potential prognostic marker for HCC.

Ca(2+) and EGF induce the differentiation of human embryo mesenchymal stem cells into epithelial-like cells

The mesenchymal to epithelial transition (MET) occurs in organ development and anti-tumorigenesis. We have investigated the effects of calcium (Ca(2+)) and epidermal growth factor (EGF) on human mesenchymal stem cell (hMSCs) differentiation into epithelial-like cells. hMSCs lost their biological characteristics after EGF transfection, and MET was achieved by adding 0.4 mmol Ca(2+). Western blotting and immunofluorescence showed expression of EGF, keratin, keratin 19 (K19), β1-integrin, E-cadherin and phosphorylated focal adhesion kinase (p-FAK, Ser-910) increased in hMSCs infected with EGF and exposed to Ca(2+), although Smad3 activation was downregulated. hMSCs co-stimulated with EGF transfection and Ca(2+) can therefore differentiate into epithelial-like cells in vitro.

mLST8 Promotes mTOR-Mediated Tumor Progression

The activity of the mechanistic target of rapamycin (mTOR) is elevated in various types of human cancers, implicating a role in tumor progression. However, the molecular mechanisms underlying mTOR upregulation remain unclear. In this study, we found that the expression of mLST8, a required subunit of both mTOR complex 1 (mTORC1) and complex 2 (mTORC2), was upregulated in several human colon and prostate cancer cell lines and tissues. Knockdown of mLST8 significantly suppressed mTORC1 and mTORC2 complex formation, and it also inhibited tumor growth and invasiveness in human colon carcinoma (HCT116) and prostate cancer (LNCaP) cells. Overexpression of mLST8 induced anchorage-independent cell growth in normal epithelial cells (HaCaT), although mLST8 knockdown had no effect on normal cell growth. mLST8 knockdown reduced mTORC2-mediated phosphorylation of AKT in both cancer and normal cells, whereas it potently inhibited mTORC1-mediated phosphorylation of 4E-BP1 specifically in cancer cells. These results suggest that mLST8 plays distinct roles in normal and cancer cells, depending upon its expression level, and that mLST8 upregulation may contribute to tumor progression by constitutively activating both the mTORC1 and mTORC2 pathways.

9q33.3, a stress-related chromosome region, contributes to reducing lung squamous cell carcinoma risk

BACKGROUND

Human chromosome 9q33.3 is one of the most important loci for pathophysiological stresses with complex genetic traits. We hypothesized that the common single-nucleotide polymorphisms on this region may affect non-small-cell lung cancer risk.

METHODS

We genotyped 43 single-nucleotide polymorphisms that span 13 genes on 9q33.3 in two independent cohorts: the discovery study including 485 cases and 532 controls (North China) and the replicative study including 1063 cases and 1247 controls (South China). Both of the discovery cohort and the replicative cohort were included in the combined study.

RESULTS

In the discovery study, we identified a potential protective locus rs10118570 in mitogen-activated protein kinase associated protein 1 with a lower population attributable risk under logistical regression adjusted by age, gender, smoking, and drinking status (adjusted odds ratio [OR] 0.26, 95% confidence interval [CI] 0.10-0.71, p = 1.138 × 10 for genotype GG in lung squamous cell carcinoma). This protective quality increased in a dose-dependent manner as genotype GG decreased (ptrend = 9.675 × 10). Replicative and combined studies showed consistent association for this genotype (replicative: adjusted OR 0.36, 95% CI 0.20-0.66, p = 6.109 × 10, ptrend = 7.386 × 10; combined: adjusted OR 0.33, 95% CI 0.18-0.55, p = 1.259 × 10, ptrend = 7.725 × 10).

CONCLUSION

We concluded that mitogen-activated protein kinase associated protein 1 rs10118570 may be an important protective factor for developing better management strategies in lung squamous cell carcinoma.

Mesohepatectomy for centrally located large hepatocellular carcinoma: Indications, techniques, and outcomes

BACKGROUND

Whether mesohepatectomy should be performed for large hepatocellular carcinoma (HCC) located in the central part of the liver is controversial, and the safety and long-term survival after this operation remain to be investigated.

METHODS

Between January 2002 and December 2012, 696 patients with HCC located in the central part of the liver who received liver resection in our hospital were included in this study. These patients were divided into three groups: 158 patients with large HCC (tumor size >5.0 cm) and 192 patients with small HCC (tumor size ≤ 5.0 cm) who received mesohepatectomy were classified as the mesohepatectomy for large HCC (MHG-L) group and the mesohepatectomy for small HCC (MHG-S) groups, respectively, and 346 patients with large HCC who received hemihepatectomy or less were classified as the non-mesohepatectomy for large HCC (NMHG-L) group. The operative indications, techniques, and outcomes of the three groups were analyzed retrospectively.

RESULTS

There were no substantial differences among the three groups in in-hospital mortality or postoperative complication rates. The overall survival and disease-free survival were not different between the MHG-L group and the NMHG-L group or between the MHG-L group and the MHG-S group. Univariable and multivariable analyses of the MHG-L mesohepatectomy group indicated that cirrhosis, tumor number, and vascular invasion were independent risk factors of poor long-term survival of mesohepatectomy. In the MHG-L and NMHG-L groups, solitary large hepatocellular carcinoma had better long-term survival than nodular large hepatocellular carcinoma.

CONCLUSION

Mesohepatectomy is safe and efficacious for BCLC B/C patients who have centrally located large HCC, especially for solitary tumors, with good survival outcomes.

MicroRNA-331-3p promotes proliferation and metastasis of hepatocellular carcinoma by targeting PH domain and leucine-rich repeat protein phosphatase

Hepatocellular carcinoma (HCC) is a highly invasive tumor with frequent intrahepatic or pulmonary metastasis, which is the main reason for high recurrence and poor survival of HCC after liver resection. However, the mechanisms for metastasis remain incompletely clear. Given that microRNAs (miRNAs) are implicated in HCC progression, we explored a potential role of miRNAs in metastasis by performing miRNA expression profiling in three subtypes of HCC with different metastatic potentials. We discovered miR-331-3p as one of most significantly overexpressed miRNAs and highly associated with metastasis of HCC. Increased expression of miR-331-3p was correlated with poor long-term survival of HCC. We provided both in vivo and in vitro evidence demonstrating that miR-331-3p promoted proliferation and metastasis of HCC cells. Using an integrated approach, we uncovered that PH domain and leucine-rich repeat protein phosphatase (PHLPP) was a novel target of miR-331-3p. Indeed, the miR-331-3p-mediated effects were antagonized by reexpression of PHLPP or mimicked by silencing of PHLPP. We further showed that miR-331-3p-mediated inhibition of PHLPP resulted in stimulation of protein kinase B (AKT) and subsequent epithelial mesenchymal transition (EMT). Finally, inhibition of miR-331-3p through a jetPEI-mediated delivery of anti-miR-331-3p vector resulted in marked inhibition of proliferation and metastasis of HCC in xenograft mice.

CONCLUSION

miR-331-3p promotes proliferation and EMT-mediated metastasis of HCC through suppression of PHLPP-mediated dephosphorylation of AKT. Our work implicates miR-331-3p as a potential prognostic biomarker and a novel therapeutic target.