Gankyrin is frequently overexpressed in breast cancer and is associated with ErbB2 expression

Synthesis and evaluation of 2,5-substituted pyrimidines as small-molecule gankyrin binders

Background: Gankyrin is an ankyrin-repeat protein that promotes cell proliferation, tumor development and cancer progression when overexpressed. Aim: To design and synthesize a novel series of gankyrin-binding small molecules predicated on a 2,5-pyrimidine scaffold. Materials & methods: The synthesized compounds were evaluated for their antiproliferative activity, ability to bind gankyrin and effects on cell cycle progression and the proteasomal degradation pathway. Results: Compounds 188 and 193 demonstrated the most potent antiproliferative activity against MCF7 and A549 cells, respectively. Both compounds also demonstrated the ability to effectively bind gankyrin, disrupt proteasomal degradation and inhibit cell cycle progression. Conclusion: The 2,5-pyrimidine scaffold exhibits a novel and promising strategy for binding gankyrin and inhibiting cancer cell proliferation.

Gankyrin inhibits ferroptosis through the p53/SLC7A11/GPX4 axis in triple-negative breast cancer cells

Gankyrin is found in high levels in triple-negative breast cancer (TNBC) and has been established to form a complex with the E3 ubiquitin ligase MDM2 and p53, resulting in the degradation of p53 in hepatocarcinoma cells. Therefore, this study sought to determine whether gankyrin could inhibit ferroptosis through this mechanism in TNBC cells. The expression of gankyrin was investigated in relation to the prognosis of TNBC using bioinformatics. Co-immunoprecipitation and GST pull-down assays were then conducted to determine the presence of a gankyrin and MDM2 complex. RT-qPCR and immunoblotting were used to examine molecules related to ferroptosis, such as gankyrin, p53, MDM2, SLC7A11, and GPX4. Additionally, cell death was evaluated using flow cytometry detection of 7-AAD and a lactate dehydrogenase release assay, as well as lipid peroxide C11-BODIPY. Results showed that the expression of gankyrin is significantly higher in TNBC tissues and cell lines, and is associated with a poor prognosis for patients. Subsequent studies revealed that inhibiting gankyrin activity triggered ferroptosis in TNBC cells. Additionally, silencing gankyrin caused an increase in the expression of the p53 protein, without altering its mRNA expression. Co-immunoprecipitation and GST pull-down experiments indicated that gankyrin and MDM2 form a complex. In mouse embryonic fibroblasts lacking both MDM2 and p53, this gankyrin/MDM2 complex was observed to ubiquitinate p53, thus raising the expression of molecules inhibited by ferroptosis, such as SLC7A11 and GPX4. Furthermore, silencing gankyrin in TNBC cells disrupted the formation of the gankyrin/MDM2 complex, hindered the degradation of p53, increased SLC7A11 expression, impeded cysteine uptake, and decreased GPX4 production. Our findings suggest that TNBC cells are able to prevent cell ferroptosis through the gankyrin/p53/SLC7A11/GPX4 signaling pathway, indicating that gankyrin may be a useful biomarker for predicting TNBC prognosis or a potential therapeutic target.

Small-Molecule Gankyrin Inhibition as a Therapeutic Strategy for Breast and Lung Cancer

Gankyrin is an oncoprotein responsible for the development of numerous cancer types. It regulates the expression levels of multiple tumor suppressor proteins (TSPs) in liver cancer; however, gankyrin's regulation of these TSPs in breast and lung cancers has not been thoroughly investigated. Additionally, no small-molecule gankyrin inhibitor has been developed which demonstrates potent anti-proliferative activity against gankyrin overexpressing breast and lung cancers. Herein, we are reporting the structure-based design of gankyrin-binding small molecules which potently inhibited the proliferation of gankyrin overexpressing A549 and MDA-MB-231 cancer cells, reduced colony formation, and inhibited the growth of 3D spheroids in an in vitro tumor simulation model. Investigations demonstrated that gankyrin inhibition occurs through either stabilization or destabilization of its 3D structure. These studies shed light on the mechanism of small-molecule inhibition of gankyrin and demonstrate that gankyrin is a viable therapeutic target for the treatment of breast and lung cancer.

Biological effects and regulation of IGFBP5 in breast cancer

The insulin-like growth factor receptor (IGF1R) pathway plays an important role in cancer progression. In breast cancer, the IGF1R pathway is linked to estrogen-dependent signaling. Regulation of IGF1R activity is complex and involves the actions of its ligands IGF1 and IGF2 and those of IGF-binding proteins (IGFBPs). Six IGFBPs are known that share the ability to form complexes with the IGFs, by which they control the bioavailability of these ligands. Besides, each of the IGFBPs have specific features. In this review, the focus lies on the biological effects and regulation of IGFBP5 in breast cancer. In breast cancer, estrogen is a critical regulator of IGFBP5 transcription. It exerts its effect through an intergenic enhancer loop that is part of the chromosomal breast cancer susceptibility region 2q35. The biological effects of IGFBP5 depend upon the cellular context. By inhibiting or promoting IGF1R signaling, IGFBP5 can either act as a tumor suppressor or promoter. Additionally, IGFBP5 possesses IGF-independent activities, which contribute to the complexity by which IGFBP5 interferes with cancer cell behavior.

Optimizing the aryl-triazole of cjoc42 for enhanced gankyrin binding and anti-cancer activity

Gankyrin is an oncoprotein overexpressed in numerous cancer types and appears to play a key role in regulating cell proliferation, cell growth, and cell migration. These roles are largely due to gankyrin's protein-protein interaction with the 26S proteasome. We previously published a study exploring the aryl sulfonate ester of cjoc42 in an effort to enhance gankyrin binding and inhibit cancer cell proliferation. In order to further improve the gankyrin binding ability of the cjoc42 scaffold, an extensive SAR for the aryl-triazole moiety of cjoc42 was developed. Our cjoc42 derivatives exhibited enhanced gankyrin binding, as well as enhanced antiproliferative activity against Hep3B, HepG2, A549, and MDA-MB-231 cancer cell lines.

POTEE promotes colorectal carcinoma progression via activating the Rac1/Cdc42 pathway

Current studies have shown that POTE ankyrin domain family members have high expressions as tumor antigens in malignant tumors, such as prostate cancer, ovarian cancer, breast cancer and the like. POTEE is a member of the POTE anchor protein family E. However, its role in colorectal carcinoma (CRC) has not been studied. In this study, the function of POTEE in CRC was examined for the first time and its correlation with CRC cell biological behaviors was analyzed. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blotting, and immunohistochemistry revealed that POTEE was remarkably overexpressed in CRC and associated with an aggressive phenotype. We also found that POTEE was localized in the cytoplasm. In addition, downregulation of POTEE expression can notably inhibit the proliferation, migration, and invasion of CRC cell in vitro, and repressed tumor growth and metastasis in vivo. In contrast, overexpression of POTEE could promote the aggressive behaviors of CRC cells. Mechanistically, POTEE promoted CRC migration, invasion and epithelial-mesenchymal transition (EMT) by increasing the activation of Rac1 and Cdc42. To summarize, these results suggested that POTEE might serve as an oncogene for CRC tumorigenesis and progression, and may become a novel molecular marker for clinical diagnosis and treatment.

Increased Expression of Gankyrin and Stemness Factor Oct-4 are Associated with Unfavorable Clinical Outcomes and Poor Benefit of Tamoxifen in Breast Carcinoma Patients

Tamoxifen is the most important treatment component in estrogen receptor positive (ER+) breast carcinoma patients. Tamoxifen resistance incidence presents an important obstacle in clinical treatment. Mechanisms underlying tamoxifen refractory are not completely understood. Although elevated expression of Gankyrin (P28GANK) and stem cell markers Nanog, Oct-4 and Sox-2 have been reported in breast carcinoma, their role in tamoxifen resistance progression has not been explored. In the present study, P28GANK and stem cell markers Nanog, Oct-4 and Sox-2 expression were evaluated using quantitative RT-PCR and immunohistochemical technology in 72 breast carcinoma patients who received tamoxifen as adjuvant anti-hormone treatment. Expression data were correlated with the clinical outcome and survival of patients. Data analysis showed that P28GANK, Oct-4 and Sox-2 transcripts were significantly overexpressed in tamoxifen resistance patients. Immunohistochemical staining indicated that protein expression of P28GANK and Oct-4 were also significantly higher in tamoxifen resistance patients. We have shown a positive correlation between mRNA and protein expression of P28GANK, Oct-4 and Sox-2. Multivariate logistic regression analysis indicated that P28GANK (P = 0.002) and Oct-4 (P = 0.013) overexpression could be negative independent factors of disease outcome. Additionally, in the whole study group, multivariate Cox regression analysis revealed that high expression of P28GANK and Oct-4 remained significant and unfavorable predictive factors for patients' survival. These findings suggest that Gankyrin and Oct-4 overexpression could promote tamoxifen refractory in breast cancer patients. More studies are warranted to clarify the predictive role of these potential biomarkers for patients who don't benefit from tamoxifen treatment and their possible application as prognostic markers in ER⁺ tamoxifen-treated breast carcinoma patients.

The oncogene Gankyrin is expressed in testicular cancer and contributes to cisplatin sensitivity in embryonal carcinoma cells

BACKGROUND

Testicular germ cell cancer (TGCC) develops from pre-malignant germ neoplasia in situ (GCNIS) cells. GCNIS originates from fetal gonocytes (POU5F1+/MAGE-A4-), which fail to differentiate to pre-spermatogonia (POU5F1-/MAGE-A4+) and undergo malignant transformation. Gankyrin is an oncogene which has been shown to prevent POU5F1 degradation and specifically interact with MAGE-A4 in hepatocellular carcinoma (HCC) cells. We aimed to investigate the role of Gankyrin in progression from gonocyte to pre-invasive GCNIS and subsequent invasive TGCC.

METHODS

We determined Gankyrin expression in human fetal testicular tissue (gestational weeks 9-20; n = 38), human adult testicular tissue with active spermatogenesis (n = 9), human testicular tissue with germ cell maturation delay (n = 4), testicular tissue from patients with pre-invasive GCNIS (n = 6), and invasive TGCC including seminoma (n = 6) and teratoma (n = 7). Functional analysis was performed in-vitro by siRNA knock-down of Gankyrin in the NTera2 cells (derived from embryonal carcinoma).

RESULTS

Germ cell expression of Gankyrin was restricted to a sub-population of prespermatogonia in human fetal testes. Nuclear Gankyrin was also expressed in GCNIS cells of childhood and adult pre-invasive TGCC patients, and in GCNIS from seminoma and non-seminoma patients. Cytoplasmic expression was observed in seminoma tumour cells and NTera2 cells. Gankyrin knock-down in NTera2 cells resulted in an increase in apoptosis mediated via the TP53 pathway, whilst POU5F1 expression was unaffected. Furthermore, Gankyrin knock-down in NTera2 cells increased cisplatin sensitivity with an increase in cell death (13%, p < 0.05) following Gankyrin knock-down, when compared to cisplatin treatment alone, likely via BAX and FAS. Our results demonstrate that Gankyrin expression changes in germ cells during normal transition from gonocyte to prespermatogonia. In addition, changes in Gankyrin localisation are associated with progression of pre-invasive GCNIS to invasive TGCC. Furthermore, we found that Gankyrin is involved in the regulation of NTera2 cell survival and that a reduction in Gankyrin expression can modulate cisplatin sensitivity.

CONCLUSIONS

These results suggest that manipulation of Gankyrin expression may reduce the cisplatin dose required for the treatment of TGCC, with benefits in reducing dose-dependent side effects of chemotherapy. Further studies are required in order to assess the effects of modulating Gankyrin on GCNIS/TGCC using in vivo models.

Gankyrin drives metabolic reprogramming to promote tumorigenesis, metastasis and drug resistance through activating β-catenin/c-Myc signaling in human hepatocellular carcinoma

Gankyrin plays important roles in tumorigenicity and metastasis of hepatocellular carcinoma (HCC). We have for the first time investigated the effects of Gankyrin on glycolysis and glutaminolysis both in vitro and in vivo, including in patient-derived xenografts. We reported Gankyrin increases glucose consumption, lactate production, glutamine consumption and glutamate production in HCC through upregulating the expression of the transporters and enzymes involved in glycolysis and glutaminolysis, including HK2, GLUT1, LDHA, PKM2, ASCT2 and GLS1. We further demonstrated that Gankyrin drives glycolysis and glutaminolysis through upregulating c-Myc via activating β-catenin signaling. Importantly, we found c-Myc mediated metabolic reprogramming might contribute to the tumorigenicity, metastasis and drug resistance induced by Gankyrin. c-Myc inhibitor synergizes with Sorafenib or Regorafenib to suppress HCC PDX tumors with high Gankyrin levels. We detected a significant correlation between Gankyrin and β-catenin expression levels in a cohort of HCC biopsies, and combination of these two parameters is a more powerful predictor of poor prognosis. Collectively, our results uncovered that Gankyrin functions as an essential regulator in glycolysis and glutaminolysis via activation of β-catenin/c-Myc to promotes tumorigenesis, metastasis and drug resistance in human HCC.

Gankyrin Drives Malignant Transformation of Gastric Cancer and Alleviates Oxidative Stress via mTORC1 Activation

Gastric cancer, as a malignant epithelial tumor, is a major health threat leading to poor overall survival and death. It is usually diagnosed at an advanced stage due to asymptomatic or only nonspecific early symptoms. The present study demonstrated that gankyrin contributes to the early malignant transformation of gastric cancer and can be selected to predict the risk of gastric cancer in those patients harboring the precancerous lesions (dysplasia and intestinal metaplasia). In addition, a new insight into gastric cancer was provided, which stated that gankyrin alleviates oxidative stress via mTORC1 pathway activation. It can potentiate the mTORC1 by PGK1-AKT signaling that promotes the tumor process, and this phenomenon is not completely consistent with the previous report describing colorectal cancer.

Gankyrin promotes epithelial-mesenchymal transition and metastasis in NSCLC through forming a closed circle with IL-6/ STAT3 and TGF-β/SMAD3 signaling pathway

Our previous research showed that Gankyrin was overexpressed in NSCLC and significantly associated with clinicopathologic features and poor prognosis. In this study, we will explore potential effect of Gankyrin on EMT and metastasis in NSCLC. The ectopic higher expression of Gankyrin markedly increased the migration and invasion in NSCLC cells. In contrast, silencing Gankyrin inhibit this aggressive behavior in NSCLC cells. Further study demonstrated that overexpression of Gankyrin could decrease E-cadherin expression and increase expression of Vimentin and Twist1 at mRNA and protein levels. These data indicated that Gankyrin could facilitate occurrence and development of EMT. Also IHC analysis showed that Gankyrin expression was negatively correlated with E-cadherin expression, while positively correlated with Vimentin and Twist1 expression in NSCLC tissues. The mechanism study finally suggested that the Gankyrin-driven EMT was partially due to IL-6/p-STAT3 and TGF-β/p-SMAD3 pathways activation. Taken together, our data provided a novel mechanism of Gankyrin promoting EMT and metastasis in NSCLC through forming a closed circle with IL-6/p-STAT3 and TGF-β/p-SMAD3 signaling pathway.

Unexpected Lower Expression of Oncoprotein Gankyrin in Drug Resistant ABCG2 Overexpressing Breast Cancer Cell Lines

Background: Development of a multidrug resistance (MDR) phenotype to chemotherapy remains a major barrier in the treatment of cancer. Gankyrin (p28, p28GANK or PSMD10) is an oncoprotein overexpressed in different carcinoma cell lines. The aim of this study was to compare Gankyrin expression level in MDR cells (MCF-7/ADR and MCF-7/ MX) and non-MDR counterparts (MCF-7). Methods: Gankyrin, MDR1 (also known as ABCB1; the ATP-binding cassette sub-family B member 1) and ABCG2 (also known as BCRP; the human breast cancer resistance protein) mRNA levels were analyzed by real-time RT-PCR. Western blot analysis was used to detect the protein expression levels of Gankyrin. Results: The PCR results showed that the expression of Gankyrin was significantly lower in the ABCG2 overexpressing cell line MCF-7/MX than in non-resistanct MCF-7 cells. In contrast, there were no significant differences in mRNA expression of Gankyrin in the MDR1 overexpressing cell line MCF-7/ADR in comparison with MCF-7 cells. Similarly, Western blot analysis confirmed lower expression of Gankyrin protein in the MCF-7/MX cell line (26% compared to controls) but not in MCF-7/ADR cells. Conclusion: These findings showed that there may be a relation between down-regulation of Gankyrin and overexpression of ABCG2 but without any clear relationship with MDR1 expression in breast cancer cell lines.

Gankyrin: a novel promising therapeutic target for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is known as fifth common malignancies and third common cause of cancer-related death worldwide. The identification of various mechanisms which are involved in hepatocarcinogenesis contributes in finding a variety of cellular and molecular targets for HCC diagnosis, prevention and therapy. Among various identified targets in HCC pathogenesis, Gankyrin is a crucial oncoprotein that is up-regulated in HCC and plays a pivotal role in the initiation and progression of the HCC. Oncogenic role of Gankyrin has been found to stem from inhibition of two ubiquitous tumour suppressor proteins, retinoblastoma protein (pRb) and P53, and also modulation of several vital cellular signalling pathways including Wnt/β-Catenin, NF-κB, STAT3/Akt, IL-1β/IRAK-1 and RhoA/ROCK. As a result, Gankyrin can be considered as a potential candidate for diagnosis and treatment of HCC. In this review, we summarized the physiological function and the significant role of Gankyrin as an important therapeutic target in HCC.

A tumor suppressor role for C/EBPα in solid tumors: more than fat and blood

The transcription factor CCAAT/enhancer-binding protein alpha (C/EBPα) plays a critical role during embryogenesis and is thereafter required for homeostatic glucose metabolism, adipogenesis and myeloid development. Its ability to regulate the expression of lineage-specific genes and induce growth arrest contributes to the terminal differentiation of several cell types, including hepatocytes, adipocytes and granulocytes. CEBPA loss of-function mutations contribute to the development of ~10% of acute myeloid leukemia (AML), stablishing a tumor suppressor role for C/EBPα. Deregulation of C/EBPα expression has also been reported in a variety of additional human neoplasias, including liver, breast and lung cancer. However, functional CEBPA mutations have not been found in solid tumors, suggesting that abrogation of C/EBPα function in non-hematopoietic tissues is regulated by alternative mechanisms. Here we review the function of C/EBPα in solid tumors and focus on the molecular mechanisms underlying its tumor suppressive role.

Prognostic and clinicopathological significance of Gankyrin overexpression in cancers: evidence from a meta-analysis

Many studies have indicated that Gankyrin is a promising and novel prognostic tumor biomarker. However, the results of different studies remained controversial. Hence, a meta-analysis was undertaken to investigate the association between Gankyrin expression and cancer prognosis. Eligible studies were identified by searching the electronic databases PubMed, Embase, and Cochrane Library up to November 2015. Prognostic value of Gankyrin expression was evaluated by hazard ratio with 95% confidence interval (CI). Meanwhile, relative risk (RR) with 95% CI was used to assess the effects of Gankyrin expression on clinicopathological parameters. In total, ten studies with 1,326 patients were included for final analysis. A significant association was found between Gankyrin overexpression and poorer overall survival in patients with cancer (hazard ratio =1.73, 95% CI: 1.29–2.31, P=0.000). In the subgroup analysis, the association was also detected in Chinese patients and patients with cancers of the digestive system. The pooled RR indicated that Gankyrin overexpression was related to advanced tumor–node–metastasis stage (RR =0.72, 95% CI: 0.60–0.86, P=0.000), positive lymph node metastasis (RR =1.66, 95% CI: 1.41–1.94, P=0.000), and distant metastasis (RR =1.43, 95% CI: 1.20–1.70, P<0.000). The meta-analysis demonstrated that Gankyrin is a novel biomarker for predicting cancers, especially digestive system cancers, and is more suitable for predicting cancer prognoses in Asians.

Synthetic Proteins Potently and Selectively Bind the Oncoprotein Gankyrin, Modulate Its Interaction with S6 ATPase, and Suppress Gankyrin/MDM2-Dependent Ubiquitination of p53

Overexpression of the ankyrin repeat oncoprotein gankyrin is directly linked to the onset, proliferation, and/or metastasis of many cancers. The role of gankyrin in multiple disease-relevant biochemical processes is profound. In addition to other cellular processes, gankyrin overexpression leads to decreased cellular levels of p53, through a complex that involves MDM2. Thus, inhibition of this interaction is an attractive strategy for modulating oncogenic phenotypes in gankyrin-overexpressing cells. However, the lack of well-defined, hydrophobic, small-molecule binding pockets on the putative ankyrin repeat binding face presents a challenge to traditional small-molecule drug discovery. In contrast, by virtue of their size and relatively high folding energies, synthetic gankyrin-binding proteins could, in principle, compete with physiologically relevant PPIs involving gankyrin. Previously, we showed that a shape-complementary protein scaffold can be resurfaced to bind gankyrin with moderate affinity (KD ∼6 μM). Here, we used yeast display high-throughput screening, error-prone PCR, DNA shuffling, and protein engineering to optimize this complex. The best of these proteins bind gankyrin with excellent affinity (KD ∼21 nM), selectively co-purifies with gankyrin from a complex cellular milieu, modulates an interaction between gankyrin and a physiological binding partner (S6 ATPase), and suppresses gankyrin/MDM2-dependent ubiquitination of p53.

The co-expression of GPER and Gankyrin in ovarian endometriosis and its correlation with the rASRM stages

OBJECTIVE

The aim of this study was to examine the expression of G protein-coupled estrogen receptor (GPER) and Gankyrin in ovarian endometriosis, analyze their clinicopathological significance, and investigate their correlation.

METHODS

Quantitative real-time polymerase chain reaction and Western blot were performed to testify mRNA and protein expression of GPER and Gankyrin in ovarian endometriosis. Immunohistochemical staining (streptavidin-peroxidase method) was conducted to determine the expression and distribution of GPER and Gankyrin protein in matched ectopic and eutopic endometrium of endometriosis and normal endometrium. We also investigated their associations with rASRM stages and the correlation between the two proteins.

RESULTS

GPER and Gankyrin were found overexpressed in ectopic endometrium of endometriosis compared with either its eutopic counterpart or endometrium from normal patients. The immunohistochemical analysis also revealed that higher expression was observed in eutopic endometrium with or without endometriosis during proliferative phase in comparison to secretory phase. These two proteins were positively correlated with the stages of endometriosis. Moreover, a significant positive correlation was found between GPER and Gankyrin both in ectopic and eutopic endometrium of the ovarian endometriosis.

CONCLUSION

GPER and Gankyrin might be implicated in the hormonal regulation of endometriosis and be associated with the severity of endometriosis. In addition, GPER and Gankyrin were found to be positively correlated, which could possibly serve as novel therapeutic targets for this disease.

Characterization of the binding interaction between the oncoprotein gankyrin and a grafted S6 ATPase

A complex with the C-terminal portion of the proteosomal subunit S6 ATPase is the only available structure of a protein-protein interaction involving the oncoprotein gankyrin. However, difficulties associated with recombinant expression of S6 ATPase alone, or truncations thereof, have limited our understanding of this assembly. We replaced the C-terminal portion of FtsH from Escherichia coli with the structurally homologous C-terminal portion of S6 ATPase and used this grafted protein to characterize the gankyrin-S6 ATPase binding interaction by isothermal titration calorimetry.

Resurfaced shape complementary proteins that selectively bind the oncoprotein gankyrin

Increased cellular levels of protein-protein interactions involving the ankyrin repeat oncoprotein gankyrin are directly linked to aberrant cellular events and numerous cancers. Inhibition of these protein-protein interactions is thus an attractive therapeutic strategy. However, the relatively featureless topology of gankyrin's putative binding face and large surface areas involved in gankyrin-dependent protein-protein interactions present a dramatic challenge to small molecule discovery. The size, high folding energies, and well-defined surfaces present in many proteins overcome some of the challenges faced by small molecule discovery. We used split-superpositive Green Fluorescent Protein (split-spGFP) reassembly to screen a 5×10(9) library of resurfaced proteins that are shape complementary to the putative binding face of gankyrin and identified mutants that potently and selectively bind this oncoprotein in vitro and in living cells. Collectively, our findings represent the first synthetic proteins that bind gankyrin and may represent a general strategy for developing protein basic research tools and drug leads that bind disease-relevant ankyrin repeats.

MiR-605 represses PSMD10/Gankyrin and inhibits intrahepatic cholangiocarcinoma cell progression

The aberrant expression of PSMD10 has important functions in various malignancies. This study showed that PSMD10 was highly expressed and inversely correlated with the expression of miR-605 in intrahepatic cholangiocarcinoma (ICC) specimens. MiR-605 directly targeted and repressed PSMD10 expression. In addition, over-expression of miR-605 inhibited ICC cell progression both in vitro and in vivo. This effect of miR-605 on ICC cells was similar to that of PSMD10 knock-down by RNAi. Moreover, restoration of PSMD10 could reverse the phenotypic alteration caused by miR-605 in ICC cells. These results suggest a new therapeutic strategy in ICC by restoring miR-605, which is regulated by p53.

Gankyrin is frequently overexpressed in cervical high grade disease and is associated with cervical carcinogenesis and metastasis

Our previous studies have showed that Gankyrin expression is correlated with a malignant phenotype in endometrial carcinoma. Here, we investigated the possible role of Gankyrin in cervical disease. The increasing protein level of Gankyrin was observed in high-grade cervical intraepithelial neoplasia and carcinoma compared with benign cervical tissues and low-grade cervical intraepithelial neoplasia. In para-carcinoma tissues, it was found interestingly that there was no lymph node metastasis when nuclei Gankyrin was positively expressed, but lymph node metastasis rate was 30% (6/20) when nuclei Gankyrin was negatively expressed. In vitro, the transfection of Gankyrin resulted in markedly up-regulating of Vimentin, β-catenin and Twist2, as well as down-regulating of E-cadherin in cervical carcinoma cells. Our results suggested that Gankyrin may be functional in cervical carcinogenesis and metastasis.

Gankyrin is essential for hypoxia enhanced metastatic potential in breast cancer cells

Hypoxia, a critical regulator of tumor growth and metastasis, induces the transcriptional activation of several pathways involved in proliferation, migration and invasion. Gankyrin was found to be overexpressed, and also promoted the metastasis in breast cancer cells, which is also involved in the regulation of hypoxia inducible factor‑1 and hypoxia‑inducible factor‑1α. The present study showed that gankyrin mRNA and protein expression were increased under hypoxic conditions in the BT474 breast cancer cell line, accompanied with increased ability of cell migration and invasion. Lentivirus‑mediated siRNA targeting gankyrin was transfected into BT474 cells. Wound‑healing and transwell experiments showed that gankyrin deletion abrogated the increased migration and invasion of BT474 cells due to hypoxia. In addition, E‑cadherin was found to be involved in the gankyrin induced invasion of breast cancer cells due to hypoxia. The present study indicated that gankyrin deletion abrogated the increased metastatic potential of breast cancer cells under hypoxic conditions partly through regulating E‑cadherin, suggesting that an improved understanding of gankyrin may offer a potential therapeutic target for the treatment of human breast cancer metastasis.

LBH589 Inhibits proliferation and metastasis of hepatocellular carcinoma via inhibition of gankyrin/STAT3/Akt pathway

Background

Gankyrin has shown to be overexpressed in human liver cancers and plays a complex role in hepatocarcinogenesis. Panobinostat (LBH589), a new hydroxamic acid-derived histone deacetylase inhibitor has shown promising anticancer effects recently. Here, we investigated the potential of LBH589 as a form of treatment for hepatocellular carcinoma (HCC).

Methods

Gankyrin plasmid was transfected into HCC cells, and the cells were selected for more than 4 weeks by incubation with G418 for overexpression clones. The therapeutic effects of LBH589 were evaluated in vitro and in vivo. Cell proliferation, apoptosis, cell cycle, invasive potential, and epithelial-mesenchy-mal transition (EMT) were examined.

Results

LBH589 significantly inhibited HCC growth and metastasis in vitro and in vivo. Western blotting analysis indicated that LBH589 could decrease the expression of gankyrin and subsequently reduced serine-phosphorylated Akt and tyrosine-phosphorylated STAT3 expression although the total Akt and STAT3 were unaffected. LBH589 inhibited metastasis in vitro via down-regulation of N-cadherin, vimentin, TWIST1, VEGF and up-regulation of E-cadherin. LBH589 also induced apoptosis and G1 phase arrest in HCC cell lines. Ectopic expression of gankyrin attenuated the effects of LBH589, which indicates that gankyrin might play an important role in LBH589 mediated anticancer effects. Lastly, in vivo study indicated that LBH589 inhibited tumor growth and metastasis, without discernable adverse effects comparing to control group, with abrogating gankyrin/STAT3/Akt pathway.

Conclusions

Our results suggested that LBH589 could inhibit HCC growth and metastasis through down-regulating gankyrin/STAT3/Akt pathway. LBH589 may present itself as a novel therapeutic strategy for HCC.