Therapeutic and prognostic importance of epithelial-mesenchymal transition in liver cancers: insights from experimental models

HMGA2 promotes nasopharyngeal carcinoma progression and is associated with tumor resistance and poor prognosis

Nasopharyngeal carcinoma (NPC), as one of the most prevalent malignancies in the head and neck region, still lacks a complete understanding of its pathogenesis. Presently, radiotherapy, concurrent chemoradiotherapy, and targeted therapy stand as the primary modalities for treating NPC. With advancements in medicine, the cure rates for nasopharyngeal carcinoma have been steadily increasing. Nevertheless, recurrence and metastasis persist as the primary reasons for treatment failure. Consequently, a profound exploration of the molecular mechanisms underlying the occurrence and progression of nasopharyngeal carcinoma, along with the exploration of corresponding therapeutic approaches, becomes particularly imperative in the quest for comprehensive solutions to combat this disease. High mobility group AT-hook 2 (HMGA2) is a pivotal protein capable of altering chromatin structure, regulating gene expression, and influencing transcriptional activity. In the realm of cancer research, HMGA2 exhibits widespread dysregulation, playing a crucial role in nearly all malignant tumors. It is implicated in various tumorigenic processes, including cell cycle regulation, cell proliferation, epithelial-mesenchymal transition, angiogenesis, tumor invasion, metastasis, and drug resistance. Additionally, HMGA2 serves as a molecular marker and an independent prognostic factor in certain malignancies. Recent studies have increasingly unveiled the critical role of HMGA2 in nasopharyngeal carcinoma (NPC), particularly in promoting malignant progression, correlating with tumor resistance, and serving as an independent adverse prognostic factor. This review focuses on elucidating the oncogenic role of HMGA2 in NPC, suggesting its potential association with chemotherapy resistance in NPC, and proposing its candidacy as an independent factor in nasopharyngeal carcinoma prognosis assessment.

Humanized disulfide-stabilized diabody against fibroblast growth factor-2 inhibits PD-L1 expression and epithelial-mesenchymal transition in hepatoma cells through STAT3

Fibroblast growth factor 2 (FGF2) plays an important role in tumor angiogenesis. Humanized disulfide-stable double-chain antibody against fibroblast growth factor-2 (anti-FGF2 ds-Diabody) is a small molecule antibody with good tissue permeability and low immunogenicity, which has potential in tumor-targeted therapy. This study intended to investigate the effect of anti-FGF2 ds-Diabody on the migration and expression of programmed death-ligand1 (PD-L1) in hepatocellular carcinoma (HCC) cells. The anti-FGF2 ds-Diabody was expressed under methanol induction and purified with Ni2+ -affinity chromatography. Anti-FGF2 ds-Diabody significantly inhibited cell viability and proliferation in SK-Hep1 and HepG2 cells as confirmed by CCK-8 assays and colony formation assays. Western blot assays indicated that the proliferation of SK-Hep1 and HepG2 cells was inhibited by anti-FGF2 ds-Diabody through inhibiting the phosphorylation activation of AKT and MAPK. The results of transwell and western blot assays showed that the migration and invasion of SK-Hep1 and HepG2 cells were suppressed by anti-FGF2 ds-Diabody by affecting the epithelial-mesenchymal transition (EMT) process. Meanwhile, anti-FGF2 ds-Diabody inhibited the expression of PD-L1, and STAT3 participated in this process. Analysis of RT-PCR and Western blot suggested that fibroblast growth factor receptor 4 inhibitor 1 (FGFR4-IN-1) suppressed the expression of PD-L1, while STAT3 overexpression reversed this inhibitory effect. In addition, overexpression of STAT3 promoted migration and invasion and restored the suppressive effect of anti-FGF2 ds-Diabody on EMT. In conclusion, anti-FGF2 ds-Diabody could inhibit the expression of PD-L1 and EMT of hepatoma cells through FGF2/FGFR4/STAT3 axis. These results suggested that anti-FGF2 ds-Diabody has potential clinical application in inhibiting metastasis and immune escape of hepatocellular carcinoma.

An Overview on the Role of miR-451 in Lung Cancer: Diagnosis, Therapy, and Prognosis

MicroRNAs (miRNAs) are highly conserved non-coding RNAs involved in many physiological processes such as cell proliferation, inhibition, development of apoptosis, differentiation, suppresses tumorigenicity, and regulating cell growth. The description of the alterations of miRNA expression patterns in cancers will be helpful to recognize biomarkers for early detection and possible therapeutic intervention in the treatment of cancers. Recent studies have shown that miR-451 is broadly dysregulated in lung cancer and is a crucial agent in lung tumor progression. This review summarizes recent advances of the potential role of miR-451 in lung cancer diagnosis, prognosis, and treatment and provides an insight into the potential use of miR-451 for the development of advanced therapeutic methods in lung cancer.

Investigation of the role of cullin 4A overexpression in human liver cancer

Cullin 4A (CUL4A) is the major component of cullin‑RING‑based E3 ubiquitin‑protein ligase complexes, which regulate the ubiquitination of target proteins. The overexpression of CUL4A has been associated with the development and progression of various cancer types. However, a detailed understanding of the role of CUL4A in human liver cancer has not been determined by previous studies. In the present study, the association between human liver cancer and CUL4A expression was investigated. The expression of CUL4A in liver cancer tissues and paracancerous tissues of patients was investigated by reverse transcription‑quantitative polymerase chain reaction, western blotting and immunohistochemical staining. Overexpression and knockdown of CUL4A were induced with an overexpression vector and small interfering RNA transfection, respectively, in human liver cancer cell lines, and the effects on cell proliferation were analyzed by a Cell Counting Kit‑8 assay to investigate the role of CUL4A in human liver cancer. Cell migration, invasion, apoptosis and the cell cycle were also analyzed following transfection. The results of the present study revealed that the mRNA and protein expression of CUL4A was increased in the liver cancer tissues compared with the paracancerous tissues of 3 patients. Additionally, the results demonstrated that downregulation of CUL4A expression inhibited cell proliferation, migration and invasion, and increased the percentage of cell apoptosis, in HEPG2 and MHCC97‑H cells, while CUL4A overexpression led to the opposite effects. Therefore, the results of the current study indicated that CUL4A may serve an important role in the development and progression of human liver cancer, and highlights the potential of CUL4A as a novel target in the diagnosis and treatment of human liver cancer and potentially other cancer types.

S100A11 promotes TGF-β1-induced epithelial-mesenchymal transition through SMAD2/3 signaling pathway in intrahepatic cholangiocarcinoma

AIM

Our previous study found S100A11 was significantly raised in intrahepatic cholangiocarcinoma cells, but the relationship between S100A11 and intrahepatic cholangiocarcinoma remains unclear.

METHODS

We investigated the effect of silencing S100A11 on TGF-β1-induced epithelial-mesenchymal transition (EMT), cell migration and invasion.

RESULTS

Our results demonstrated silencing S100A11 inhibited TGF-β1-induced cell migration, invasion and EMT, expression of EMT markers E-cadherin, N-cadherin, β-catenin, vimentin, Slug and Snail was reversed. Furthermore, TGF-β1-induced p-SMAD2 and 3 were also inhibited due to low S100A11 expression.

CONCLUSION

Our present study indicated that S100A11 promotes EMT through accumulation of TGF-β1 expression, and TGF-β1-induced upregulation of p-SMAD2 and 3.

Effect of high WDR5 expression on the hepatocellular carcinoma prognosis

WD repeat domain 5 (WDR5) serves an important role in various biological functions through the epigenetic regulation of gene transcription. Aberrant expression of WDR5 has been observed in various types of human cancer, including prostate cancer, breast cancer and leukemia. However, the role of WDR5 expression and its clinical implications in hepatocellular carcinoma (HCC) remain largely unknown. The present study investigated the WDR5 expression pattern in HCC. It was demonstrated that the mRNA and protein levels of WDR5 were upregulated in HCC cancer tissues compared with normal adjacent tissues using reverse transcription-quantitative polymerase chain reaction and western blotting. Furthermore, the elevated WDR5 protein level was significantly associated with the histological grade (P=0.038), tumor size (P=0.023), tumor-node-metastasis stage (P=0.035) and reduced long-term survival time. Additionally, it was demonstrated through the shRNA-mediated knockdown of WDR5 in HCC cells in vitro that WDR5 expression promotes cell proliferation using an MTT assay. Taken together, the results suggested that WDR5 overexpression may have an oncogenic effect in HCC, and may be a promising biomarker for the diagnosis and prognosis of HCC.

Nemopilema nomurai jellyfish venom exerts an anti-metastatic effect by inhibiting Smad- and NF-κB-mediated epithelial-mesenchymal transition in HepG2 cells

Epithelial-mesenchymal transition (EMT) is a key initial step in metastasis for malignant cancer cells to obtain invasive and motile properties. Inhibiting EMT has become a new strategy for cancer therapy. In our previous in vivo study, Nemopilema nomurai jellyfish venom (NnV) -treated HepG2 xenograft mice group showed that E-cadherin expression was strongly detected compared with non-treated groups. Therefore, this study aimed to determine whether NnV could inhibit the invasive and migratory abilities of HepG2 human hepatocellular carcinoma cells and to examine its effect on EMT. Our results revealed that transforming growth factor (TGF)-β1 induced cell morphological changes and downregulated E-cadherin and β-catenin expression, but upregulated N-cadherin and vimentin expression through the Smad and NF-κB pathways in HepG2 cells. Treatment of TGF-β1-stimulated HepG2 cells with NnV reversed the EMT-related marker expression, thereby inhibiting cell migration and invasion. NnV also significantly suppressed the activation of p-Smad3, Smad4, and p-NF-κB in a dose-dependent manner. These data indicated that NnV can significantly suppress cell migration and invasion by inhibiting EMT in HepG2 cells, and therefore might be a promising target for hepatocellular carcinoma therapeutics.

Knocking down MiR-15a expression promotes the occurrence and development and induces the EMT of NSCLC cells in vitro

Non-small cell lung cancer (NSCLC) is a major type of lung cancer, with the highest mortality rate in all cancers. For all stages of NSCLC, the five-year survival is less than fifteen percent. Epithelial-mesenchymal transition (EMT) is a significant process in tumor occurrence and development, in which microRNAs may play an important role. In many cancers, microRNA-15's family member can act as suppressors or oncogenes of tumors; however, the relation between these microRNAs and EMT in lung cancer remains unclear. According to our study, miR-15a expression decreased in tumor tissues compared with than that in adjacent tissue samples. Knocking down miR-15a expression in NSCLC cells inhibited apoptosis and facilitated cell proliferation and invasion, and. Moreover, down-regulating miR-15a decreased the expression of an EMT-associated protein, E-cadherin, while increased those of vimentin, N-cadherin, and slug.

Role of IQGAP3 in metastasis and epithelial-mesenchymal transition in human hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most lethal cancers worldwide owing to its high rates of metastasis and recurrence. The oncogene IQ motif-containing GTPase activating protein 3 (IQGAP3) is ubiquitously overexpressed in several human cancers, including liver, ovary, lung, large intestine, gastric, bone marrow, and breast malignancies and is involved in the invasion and metastasis of cancer cells. Therefore, we aimed to determine the biological role and molecular mechanism of IQGAP3 in HCC.

Methods

We used 120 archived clinical HCC samples, 9 snap-frozen HCC tumor tissues, and 4 normal liver tissues. Expression of IQGAP3 mRNA and protein in HCC cell lines (Hep3B, SMMC-7721, HCCC-9810, HepG2, BEL-7404, HCCLM3, QGY-7701, Huh7, and MHCC97H) and normal liver epithelial cells LO2 was examined by western blot, quantitative polymerase chain reaction, and immunohistochemistry. In addition, wound-healing and transwell matrix penetration assays were used to assess the migratory and invasive abilities of HCC cells, respectively.

Results

Expression of the IQGAP3 was robustly upregulated in HCC cells and tissues. High expression of IQGAP3 in HCC correlated with aggressive clinicopathological features and was an independent poor prognostic factor for overall survival. Furthermore, ectopic expression of IQGAP3 markedly enhanced HCC cell migration, invasion, and epithelial-to-mesenchymal transition (EMT) in vitro and promoted metastasis of orthotopic hepatic tumors in nude mice. Conversely, silencing endogenous IQGAP3 showed an opposite effect. Mechanistically, IQGAP3 promoted EMT and metastasis by activating TGF-β signaling.

Conclusions

IQGAP3 functions as an important regulator of metastasis and EMT by constitutively activating the TGF-β signaling pathway in HCC. Our findings present new evidence of the role of IQGAP3 in EMT and metastasis, indicating its potential as a prognostic biomarker candidate and a therapeutic target against HCC.

The regulation of proteins associated with the cytoskeleton by hepatitis B virus X protein during hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is a major malignant disease worldwide, and chronic hepatitis B virus (HBV) infection is one of the primary causes for this type of cancer. Hepatitis B virus X protein (HBx) is a non-structural protein encoded by the viral genome that has significant effects on the pathogenesis of HCC. With the development of high-throughput assays and technologies, the abnormal HBx-induced expression of certain cellular proteins with assorted biological functions has been investigated. These target proteins identified by various methods include specific proteins associated with the cellular cytoskeleton, which contribute to HBx-induced hepatocarcinogenesis. In addition, the cytoskeletal proteins deregulated by HBx are involved in cell morphogenesis, adhesion, migration and proliferation. This review aims to summarize the current understanding of the expression profiles of HBx-associated cytoskeletal proteins, as well as their complex functions and underlying mechanisms in hepatocarcinogenesis. Considering that the potential therapeutics for various types of tumors may function through the stabilization of cytoskeletal proteins in order to restrict cellular movement and limit intracellular processes, clarifying the mechanisms underlying protein-associated cytoskeleton dysregulation by HBx may provide novel possibilities and potent therapeutic targets for HBV-associated HCC.

Treatment with the herbal formula Songyou Yin inhibits epithelial-mesenchymal transition in hepatocellular carcinoma through downregulation of TGF-β1 expression and inhibition of the SMAD2/3 signaling pathway

It was previously reported that treatment with the herbal formula Songyou Yin (SYY) may serve a role in attenuating epithelial-mesenchymal transition (EMT). In the present study, the effect of treatment with SYY on transforming growth factor-β1 (TGF-β1)-induced EMT was investigated and the potential underlying molecular mechanisms were evaluated. MHCC97H cells were pretreated with SYY for 4 weeks and subsequently named MHCC97HSYY cells. Simultaneously, MHCC97H cells were cultured for 4 weeks without SYY and used as a negative control. Western blot analysis and enzyme-linked immunosorbent assays demonstrated that treatment with SYY inhibited EMT-associated changes and TGF-β1 expression in MHCC97H cells. MHCC97H and MHCC97HSYY cells were treated with 10 ng/ml TGF-β1 to induce EMT. The results of the present study demonstrated that pretreatment with SYY markedly inhibited TGF-β1-induced morphological changes, and reversed the expression of the EMT markers E-cadherin and N-cadherin. In addition, expression levels of the TGF-β1 downstream proteins, phosphorylated mothers against decapentaplegic homologs (p-SMAD)2 and 3, were reduced. Transwell assays indicated that pretreatment with SYY inhibited TGF-β1-induced cancer cell invasion and migration. The results of the present study indicate that SYY inhibited EMT through attenuation of TGF-β1 expression, and downregulation of p-SMAD2 and 3.

Transforming Growth Factor β1 Promotes Migration and Invasion of Human Hepatocellular Carcinoma Cells Via Up-Regulation of Connective Tissue Growth Factor

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors with a poor patient survival. Expression of TGF-β1 is up-regulated in HCC and is thought to play a crucial role in the occurrence and development of HCC. However, the mechanism of TGF-β1-mediated facilitation of malignant growth and invasion remains unclear, although some previous studies highlighted a potential involvement of the connective tissue growth factor (CTGF). Here we demonstrate that the in vitro migration of the HCC cell line SMMC-7721 is increased in the presence of recombinant TGF-β1, and that this effect is reversed by the specific inhibitor SB431542. Furthermore, TGF-β1 treatment up-regulated the expression of its own mRNA as well as the expression of CTGF mRNA. The TGF-β1-stimulated migration of SMMC-7721 cells was diminished by siRNA silencing of CTGF. These in vitro observations were validated in a murine xenograft model. In particular, silencing of CTFG diminished the TGF-β1-induced tumorigenesis in experimental animals. In conclusion, TGF-β1 plays a critical role in HCC migration and invasion, and this effect is dependent on CTGF.

FCN2 inhibits epithelial-mesenchymal transition-induced metastasis of hepatocellular carcinoma via TGF-β/Smad signaling

Hepatocellular carcinoma (HCC) is currently still a major cause of cancer-related deaths. Identifying early metastatic biomarkers and therapeutic targets for HCC is of great importance. Emerging evidence suggest that epithelial-mesenchymal transitions (EMTs) play important roles in tumor metastasis and recurrence. Understanding molecular mechanisms that regulate the EMT process is crucial for improving HCC. In this study, we find Ficolin-2 (FCN2) plays an essential role in metastasis and EMT of HCC. FCN2 expression is downregulated in HCC cells and tissues. Low level of FCN2 in HCCs is correlated with aggressive metastatic features, and would be a prognostic factor for overall disease-free survival of HCC patients. Ectopic expression of FCN2 markedly inhibits HCC cells migration, invasion as well as EMT in vitro and in vivo. Moreover, TGF-β is found contribute to the function of FCN2 in suppressing metastasis and EMT of HCC. Collectively, our data suggest that FCN2 may have prognostic value in HCC metastasis. Additionally, the FCN2/ TGF-β/EMT axis identified in this study provides novel insight into the mechanisms of HCC metastasis, which may facilitate the development of new therapeutics against HCC.

miR‑205 suppresses cell proliferation, invasion, and metastasis via regulation of the PTEN/AKT pathway in renal cell carcinoma

The present study aimed to determine the importance of microRNA‑205 (miR‑205) in the proliferation, apoptosis, invasion and metastasis of renal cell carcinoma (RCC) cells and the underlying molecular mechanisms. Reverse transcription‑polymerase chain reaction was used to quantify the expression levels of miR‑205 in RCC tissue, normal tissue adjacent to carcinoma, RCC cells and normal renal cells. It was determined that the expression levels of miR‑205 in RCC tissue and cells were reduced compared with those in normal tissue and renal cells. miR‑205 mimics and the negative control were prepared and transfected into RCC cells. Cell viability and apoptosis were investigated using methyl thiazolyl tetrazolium assay and Annexin V‑fluorescein isothiocyanate/propidium iodide staining, respectively. Cell migration and invasion were evaluated with Transwell assays. The protein expression levels of E2F transcription factor 1 (E2F1), B‑cell lymphoma‑2 (Bcl‑2), E‑cadherin, vimentin, phosphatase and tensin homolog (PTEN) and phosphorylated AKT serine/threonine kinase 1 (p‑AKT) were determined with western blot analysis. It was revealed that miR‑205 promoted the apoptosis of RCC cells and suppressed their proliferation, metastasis and invasion compared with the negative control. The expression levels of E2F1, Bcl‑2, vimentin and p‑AKT were downregulated compared with the negative control. The expression levels of E‑cadherin and PTEN were upregulated in the cells transfected with miR‑205 mimics compared with the negative control group. Therefore, it was concluded that miR‑205 suppressed cell proliferation, invasion, and metastasis in RCC cells via regulation of the PTEN/AKT signaling pathway. The present study may contribute to future miRNA‑based RCC therapy.

MicroRNA-451: epithelial-mesenchymal transition inhibitor and prognostic biomarker of hepatocelluar carcinoma

Increasing evidence indicates that dysregulation of microRNAs (miRNAs) plays critical roles in malignant transformation and tumor progression. Previously, we have shown that microRNA-451 (miR-451) inhibits growth, increases chemo- or radiosensitivity and reverses epithelial to mesenchymal transition (EMT) in lung cancer. However, the roles of miR-451 in hepatocelluar carcinoma (HCC) progression and metastasis are still largely unknown. Reduced miR-451 in HCC tissues was observed to be significantly correlated with advanced clinical stage, metastasis and worse disease-free or overall survival. Through gain- and loss-of function experiments, we demonstrated that miR-451 inhibited cell growth, induced G0/G1 arrest and promoted apoptosis in HCC cells. Importantly, miR-451 could inhibit the migration and invasion in vitro, as well as in vivo metastasis of HCC cells through regulating EMT process. Moreover, the oncogene c-Myc was identified as a direct and functional target of miR-451 in HCC cells. Knockdown of c-Myc phenocopied the effects of miR-451 on EMT and metastasis of HCC cells, whereas overexpression of c-Myc partially attenuated the functions of miR-451 restoration. Furthermore, miR-451 downregulation-induced c-Myc overexpression leads to the activation of Erk1/2 signaling, which induces acquisition of EMT phenotype through regulation of GSK-3β/snail/E-cadherin and the increased expression of MMPs family members in HCC cells. Collectively, these data demonstrated that miR-451 is a novel prognostic biomarker for HCC patients and that function as a potential metastasis inhibitor in HCC cells through activation of the Erk1/2 signaling, at least partially by targeting c-Myc. Thus, targeting miR-451/c-Myc/Erk1/2 axis may be a potential strategy for the treatment of metastatic HCC.

Overexpression of CTNND1 in hepatocellular carcinoma promotes carcinous characters through activation of Wnt/β-catenin signaling

Background

Increasing evidence supports the association of CTNND1 with tumor development and progression. However, the mechanism and clinical significance of CTNND1 deregulation in hepatocellular carcinoma (HCC) remains unknown. In this study, we aim to investigate the role of CTNND1 in HCC.

Methods

qRT-PCR and immunohistochemical analyses were used to measure the levels of CTNND1 in HCC specimens and HCC cell lines. CTNND1 and shCTNND1 were transfected into HCC cell lines to investigate its role in HCC. Cell migration and invasion were measured by Transwell and Matrigel analyses in vitro. In vivo metastasis assays were performed in SCID mice.

Results

In clinical HCC samples, we found that CTNND1 expression was significantly up-regulated in cancer lesions compared with paired normal liver tissues. By silencing or overexpressing CTNND1 in HCC cells, we found that CTNND1 could promote cell proliferation, migration, and invasion in vitro. An in-vivo assay showed that CTNND1 dramatically promoted HCC cell tumor formation and metastasis. Moreover, CTNND1 promoted HCC metastasis, at least in part, by indirectly enhancing Wnt/β-catenin signaling. Consistent with these results, the expression of CTNND1 was positively correlated with β-catenin, WNT11, Cyclin D1, and BMP7 expression in human HCC specimens.

Conclusions

Our study provides evidence that CTNND1 functions as a novel tumor oncogene in HCC, and may be a potential therapeutic target for HCC management.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0344-9) contains supplementary material, which is available to authorized users.

Long non-coding RNA TUSC7 acts a molecular sponge for miR-10a and suppresses EMT in hepatocellular carcinoma

Despite advances in the roles of long non-coding RNA (lncRNA) tumor suppressor candidate 7 (TUSC7) in cancer biology, which has been identified as a tumor suppressor by regulating cell proliferation, apoptosis, migration, invasion, cell cycle, and tumor growth, the function of TUSC7 in hepatocellular carcinoma (HCC) remains unknown. In this study, we observed that the expression of TUSC7 was immensely decreased in HCC. Clinically, the lower expression of TUSC7 predicted poorer survival and may be an independent risk factor for HCC patients. Moreover, TUSC7 inhibited cell metastasis, invasion, and epithelial-to-mesenchymal transformation (EMT) through competitively binding miR-10a. Furthermore, we found that TUSC7 could decrease the expression of Eph tyrosine kinase receptor A4 (EphA4), a downstream target of miR-10a as well as an EMT suppressor, through TUSC7-miR-10a-EphA4 axis. Taken together, we demonstrate that TUSC7 suppresses EMT through the TUSC7-miR-10a-EphA4 axis, which may be a potential target for therapeutic intervention in HCC.

Epithelial-to-mesenchymal transition and hepatolithiasis

Epithelial-to-mesenchymal transition (EMT) is a complex physiological and pathological process in which epithelial cells acquire mesenchymal characteristics. EMT occurs during embryogenesis and organ development, wound healing and organ regeneration, tumor migration and invasion. In recent years, cholangiocytes have been shown to undergo EMT in different cholangiopathies including hepatolithiasis. Transforming growth factor-β/Smads signaling is considered the master regulator. The purpose of this article is to introduce the concept and type of EMT, summarize recent advances that support or refute the concept that cholangiocytes are capable of phenotype transition of hepaticlithiasis and discuss the probable mechanism.

Translating epithelial mesenchymal transition markers into the clinic: Novel insights from proteomics

The growing understanding of the molecular mechanisms underlying epithelial-to-mesenchymal transition (EMT) may represent a potential source of clinical markers. Despite EMT drivers have not yet emerged as candidate markers in the clinical setting, their association with established clinical markers may improve their specificity and sensitivity. Mass spectrometry-based platforms allow analyzing multiple samples for the expression of EMT candidate markers, and may help to diagnose diseases or monitor treatment efficiently. This review highlights proteomic approaches applied to elucidate the differences between epithelial and mesenchymal tumors and describes how these can be used for target discovery and validation.

CUL4A facilitates hepatocarcinogenesis by promoting cell cycle progression and epithelial-mesenchymal transition

CUL4A, a member of the CULLIN family, functions as a scaffold protein for an E3 ubiquitin ligase. It was reported that the CUL4A gene showed amplification in some human primary hepatocellular carcinomas (HCC). However, the exact role of CUL4A in HCC remains unknown. Here, we aimed to investigate the expression and function of CUL4A in HCC development. Through immunohistochemistry study, we showed increased CUL4A expression in HCC tissues. Statistical analysis disclosed an inverse correlation between CUL4A expression and tumor differentiation grade, and patient survival, but a positive correlation with hepatocyte proliferation as well as lymphatic and venous invasion. CUL4A expression in HCC tissues was associated with HBeAg status in patients and upregulated by HBV in HCC cell lines. Further functional assay showed that CUL4A overexpression significantly promoted growth of H22 tumor homografts in BALB/c mice. Consistently, CUL4A knockdown inhibited the proliferation of established HCC cells, accompanied by S-phase reduction and Cyclin A and Cyclin B1 repression. Furthermore, CUL4A siRNA ameliorated the motility of HCC cell lines with altered expression of epithelial-mesenchymal transition (EMT)-associated molecules. Taken together, our findings indicate that CUL4A plays a pivotal role in HCC progression and may serve as a potential marker for clinical diagnosis and target for therapy.

A "Patient-Like" Orthotopic Syngeneic Mouse Model of Hepatocellular Carcinoma Metastasis

The majority of cancer-related deaths are caused by the metastasis of the cancer rather than the primary tumor itself. Yet, the underlying mechanisms of cancer metastasis are still unclear. Animal models are essential for elucidating the mechanisms and for evaluating novel strategies for the treatment of metastatic cancers. Here, an in-depth description of a "patient-like" orthotopic syngeneic mouse model for exploring the mechanisms of metastasis of solid organ tumors is provided. The survival surgical implantation of BNL 1ME A.7R.1 mouse hepatocellular carcinoma cells directly into the liver (the organ of origin) of the inbred wild-type immune competent laboratory mouse strain, BALB/c is described. The success and reproducibility of this methodology recommends it for widespread use in elucidating the biological mechanisms of solid organ cancer metastasis.

Suppressive effects of microRNA-16 on the proliferation, invasion and metastasis of hepatocellular carcinoma cells

miR-16 is known to be abnormally expressed in hepatocellular carcinoma (HCC) cells, and the overexpression of miR-16 inhibits the proliferation, invasion and metastasis of various cancer cells. MicroRNAs (miRNAs or miRs) are closely related to the proliferation, invasion and metastasis of HCC. The present study aimed to explore the effects of miR-16 on the proliferation, invasion and metastasis of HCC cells, and to elucidate the mechanisms involved. A cell line with moderate levels of miR‑16 expression was selected from the SMMC-7721, HepG2, SK-Hep-1 and Huh‑7 HCC cells and validated by reverse transcription-PCR (RT-PCR). The effects of miR‑16 on HCC cell viability were determined by MTT assay; cell migration and invasion were determined by Transwell cell invasion assay, and apoptosis was determined by flow cytometery (FCM). Western blot analysis was used to measure the expression levels of the apoptosis-related proteins, Bax, Bcl-2, matrix metalloproteinase (MMP)-2, MMP-9, as well as to examine epithelial-mesenchymal transition (EMT), and E-cadherin, vimentin, and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway-related protein expression. The mRNA expression levels of miR‑16 were highest in the SMMC-7721 cells and lowest in the SK-Hep‑1 and Huh‑7 cells; moderate levels were observed in the HepG2 cells. The HepG2 cell line was selected as the cell line for use in the follow-up experiments, where we measured cell viability, and the expression of PI3k/Akt, Bax, Bcl-2, MMP-2 and MMP-9, and E-cadherin and vimentin. miR‑16 overexpression significantly inhibited the proliferation, invasion and metastasis of the HepG2 cells, as shown by western blot analysis. This was achieved through the upregulation of Bax expression, the downregulation of Bcl-2 expression and the decrease in the expression of MMP-2 and MMP-9. In addition the expression of E-cadherin increased and vimentin expression decreased. miR‑16 overexpression inhibited PI3K expression and Akt phosphorylation. The results of this study suggest that the overexpression of miR‑16 inhibits the proliferation, invasion and metastasis of HepG2 HCC cells, and that these effects are associated with the PI3K/Akt signaling pathway.

Adipocytes can induce epithelial-mesenchymal transition in breast cancer cells

Adipocytes are known to be involved in epithelial-mesenchymal transition (EMT) in several cancers. However, the role of adipocytes in the EMT of breast cancer cells is poorly understood. The purpose of this study was to investigate the involvement of adipocytes in the EMT in breast cancer. Breast cancer cell lines MCF-7, MDA-MB-453, MDA-MB-435S, MDA-MB-231, and MDA-MB-468 were co-cultured with adipocytes and analyzed for morphological changes, proliferation activity, EMT markers, migration, and invasion. In addition, 296 human breast cancer specimens were classified according to the presence of the fibrous or adipose stroma and analyzed by immunohistochemistry for the expression of estrogen and progesterone receptors, human epidermal growth factor receptor 2, antigen Ki-67, N-cadherin, Twist-related protein 1 (TWIST1), high-mobility group AT-hook 2, TGFβ, and S100 calcium-binding protein A4 using tissue microarray. After co-culture with adipocytes, MCF-7, MDA-MB-435S, and MDA-MB-231 cells exhibited elongated spindle-like morphology and increased proliferation; MDA-MB-435S and MDA-MB-231 cells also showed increased dispersion. In all tested breast cancer cells, adipocytes induced migration and invasion. The EMT-like phenotypic changes and increased cell migration and invasion were accompanied by the upregulation of matrix metallopeptidase 9 and TWIST1. Consistently, breast cancer tumors with the adipose stroma showed higher TWIST1 expression than those with the adipose stroma; however, no difference was observed in the levels of other EMT-related proteins. Adipocytes stimulate breast cancer cells to acquire aggressive tumor phenotype by inducing EMT-associated traits, and breast cancer with the adipose stroma expresses EMT markers as breast cancer with the fibrous stroma.

Liver-Tumor Hybrid Organoids for Modeling Tumor Growth and Drug Response In Vitro

Current in vitro models for tumor growth and metastasis are poor facsimiles of in vivo cancer physiology and thus, are not optimal for anti-cancer drug development. Three dimensional (3D) tissue organoid systems, which utilize human cells in a tailored microenvironment, have the potential to recapitulate in vivo conditions and address the drawbacks of current tissue culture dish 2D models. In this study, we created liver-based cell organoids in a rotating wall vessel bioreactor. The organoids were further inoculated with colon carcinoma cells in order to create liver-tumor organoids for in vitro modeling of liver metastasis. Immunofluorescent staining revealed notable phenotypic differences between tumor cells in 2D and inside the organoids. In 2D they displayed an epithelial phenotype, and only after transition to the organoids did the cells present with a mesenchymal phenotype. The cell surface marker expression results suggested that WNT pathway might be involved in the phenotypic changes observed between cells in 2D and organoid conditions, and may lead to changes in cell proliferation. Manipulating the WNT pathway with an agonist and antagonist showed significant changes in sensitivity to the anti-proliferative drug 5-fluoruracil. Collectively, the results show the potential of in vitro 3D liver-tumor organoids to serve as a model for metastasis growth and for testing the response of tumor cells to current and newly discovered drugs.

Cytotoxic activity of the novel small molecule AKT inhibitor SC66 in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is characterized by limited response to current drug therapies. Here, we report that SC66, a novel AKT inhibitor, reduced cell viability in a dose- and time-dependent manner, inhibited colony formation and induced apoptosis in HCC cells. SC66 treatment led to a reduction in total and phospho-AKT levels. This was associated with alterations in cytoskeleton organization, a reduction in expression levels of E-cadherin, β-catenin and phospho-FAK, together with up-regulation of Snail protein levels. All these alterations were coupled with anoikis cell death induction. In addition, SC66 induced the production of reactive oxygen species (ROS) and DNA damage. Pre-treatment with the ROS scavenger N-Acetyl-cysteine (NAC) prevented SC66-induced cell growth inhibition and anoikis. SC66 significantly potentiated the effects of both conventional chemotherapeutic and targeted agents, doxorubicin and everolimus, respectively. In vivo, SC66 inhibited tumor growth of Hep3B cells in xenograft models, with a similar mechanism observed in the in vitro model. Taken together, these data indicate that the AKT inhibitor SC66 had antitumor effects on HCC cells. This was mediated by ROS production, induction of anoikis-mediated cell death and inhibition of the AKT cell survival pathway. Our results provide a rational basis for the use of SC66 in HCC treatment.

Influence of preoperative transcatheter arterial chemoembolization on gene expression in the HIF-1α pathway in patients with hepatocellular carcinoma

PURPOSE

Although transcatheter arterial chemoembolization (TACE) is the most common treatment option in patients with hepatocellular carcinoma (HCC), its clinical benefits remain still controversial. Since TACE induces hypoxic necrosis in tumors, hypoxia-inducible factor 1α (HIF-1α) could critically affect biology in residual tumors after TACE treatment and subsequent prognosis. However, HIF-1α and its prognostic relevance in TACE have rarely been examined in human specimens. In the current study, we investigated the prognosis and expression of genes regulated by HIF-1α in HCC patients receiving preoperative TACE for the first time.

METHODS

In total, 35 patients with HCC (10 patients undergoing preoperative TACE) were retrospectively studied. The prognostic significance of TACE was analyzed using Kaplan-Meier and Cox regression models. Protein levels of HIF-1α and mRNA levels of HIF-1α-associated genes were examined using immunohistochemistry (IHC) and real-time RT-PCR, respectively.

RESULTS

Preoperative TACE was significantly associated with increased 2-year recurrence rate (80 vs. 36 %, P = 0.00402) and shorter disease-free survival (DFS) time (11.9 vs. 35.7 months, P = 0.0182). TACE was an independent prognostic factor for recurrence (P = 0.007) and poor DFS (P = 0.010) in a multivariate analysis. Immunohistochemical staining revealed in vivo activation of HIF-1α in human specimens treated with TACE. Notably, protein levels of HIF-1α were significantly increased in TACE tissues demonstrated by IHC. Transcriptional targets of HIF-1α showed mRNA expression patterns consistent with activation of HIF-1α in TACE tissues.

CONCLUSIONS

Our findings collectively demonstrate that preoperative TACE confers poor prognosis in HCC patients through activation of HIF-1α.

Evidence for and against epithelial-to-mesenchymal transition in the liver

The outcome of liver injury is determined by the success of repair. Liver repair involves replacement of damaged liver tissue with healthy liver epithelial cells (including both hepatocytes and cholangiocytes) and reconstruction of normal liver structure and function. Current dogma posits that replication of surviving mature hepatocytes and cholangiocytes drives the regeneration of liver epithelium after injury, whereas failure of liver repair commonly leads to fibrosis, a scarring condition in which hepatic stellate cells, the main liver-resident mesenchymal cells, play the major role. The present review discusses other mechanisms that might be responsible for the regeneration of new liver epithelial cells and outgrowth of matrix-producing mesenchymal cells during hepatic injury. This theory proposes that, during liver injury, some epithelial cells undergo epithelial-to-mesenchymal transition (EMT), acquire myofibroblastic phenotypes/features, and contribute to fibrogenesis, whereas certain mesenchymal cells (namely hepatic stellate cells and stellate cell-derived myofibroblasts) undergo mesenchymal-to-epithelial transition (MET), revert to epithelial cells, and ultimately differentiate into either hepatocytes or cholangiocytes. Although this theory is highly controversial, it suggests that the balance between EMT and MET modulates the outcome of liver injury. This review summarizes recent advances that support or refute the concept that certain types of liver cells are capable of phenotype transition (i.e., EMT and MET) during both culture conditions and chronic liver injury.

Essentials of circulating tumor cells for clinical research and practice

The major cause of death due to cancer is its metastatic deposit in numerous tissues and organs. The metastatic process requires the migration of malignant cells from primary sites to distant environments. Even for tumors initially spreading through lymphatic vessels, hematogenous transport is the most common metastatic pathway. The detachment of cancer cells from a primary tumor into the blood stream is called epithelial-mesenchymal transition (EMT). As these cells circulate further in the bloodstream they are known as circulating tumor cells (CTCs). The CTC population is highly resilient, enabling the cells to colonize a foreign microenvironment. Alternatively, cancer stem cells (CSCs) may arise from differentiated cancer cells through EMT and an embryonic transdifferentiation process. The presence of CTCs/CSCs in blood seems to be a determining factor of metastasis. This paper reviews various methods of clinical cancer detection as well as the biology and molecular characterization of CTCs/CSCs. Our goal was to summarize clinical studies which used CTC/CSCs for prognosis in patients with breast, colorectal, prostate, lung, ovarian, and bladder cancer.

Connective tissue growth factor is overexpressed in human hepatocellular carcinoma and promotes cell invasion and growth

AIM: To determine the expression characteristics of connective tissue growth factor (CTGF/CCN2) in human hepatocellular carcinoma (HCC) in histology and to elucidate the roles of CCN2 on hepatoma cell cycle progression and metastasis in vitro.

METHODS: Liver samples from 36 patients (who underwent hepatic resection for the first HCC between 2006 and 2011) and 6 normal individuals were examined for transforming growth factor β1 (TGF-β1) or CCN2 mRNA by in situ hybridization. Computer image analysis was performed to measure integrated optimal density of CCN2 mRNA-positive cells in carcinoma foci and the surrounding stroma. Fibroblast-specific protein-1 (FSP-1) and E-cadherin were examined to evaluate the process of epithelial to mesenchymal transition, α-smooth muscle actin and FSP-1 were detected to identify hepatic stellate cells, and CD34 was measured to evaluate the extent of vascularization in liver tissues by immunohistochemical staining. CCN2 was assessed for its stimulation of HepG2 cell migration and invasion using commercial kits while flow cytometry was used to determine CCN2 effects on HepG2 cell-cycle.

RESULTS: In situ hybridization analysis showed that TGF-β1 mRNA was mainly detected in connective tissues and vasculature around carcinoma foci. In comparison to normal controls, CCN2 mRNA was enhanced 1.9-fold in carcinoma foci (12.36 ± 6.08 vs 6.42 ± 2.35) or 9.4-fold in the surrounding stroma (60.27 ± 28.71 vs 6.42 ± 2.35), with concomitant expression of CCN2 and TGF-β1 mRNA in those areas. Epithelial-mesenchymal transition phenotype related with CCN2 was detected in 12/36 (33.3%) of HCC liver samples at the edges between carcinoma foci and vasculature. Incubation of HepG2 cells with CCN2 (100 ng/mL) resulted in more of the cells transitioning into S phase (23.85 ± 2.35 vs 10.94 ± 0.23), and induced a significant migratory (4.0-fold) and invasive (5.7-fold) effect. TGF-β1-induced cell invasion was abrogated by a neutralizing CCN2 antibody showing that CCN2 is a downstream mediator of TGF-β1-induced hepatoma cell invasion.

CONCLUSION: These data support a role for CCN2 in the growth and metastasis of HCC and highlight CCN2 as a potential novel therapeutic target.