Expression and prognostic role of Spy1 as a novel cell cycle protein in hepatocellular carcinoma

Atypical cell cycle regulation promotes mammary stem cell expansion during mammary development and tumourigenesis

BACKGROUND

The cell cycle of mammary stem cells must be tightly regulated to ensure normal homeostasis of the mammary gland to prevent abnormal proliferation and susceptibility to tumorigenesis. The atypical cell cycle regulator, Spy1 can override cell cycle checkpoints, including those activated by the tumour suppressor p53 which mediates mammary stem cell homeostasis. Spy1 has also been shown to promote expansion of select stem cell populations in other developmental systems. Spy1 protein is elevated during proliferative stages of mammary gland development, is found at higher levels in human breast cancers, and promotes susceptibility to mammary tumourigenesis when combined with loss of p53. We hypothesized that Spy1 cooperates with loss of p53 to increase susceptibility to tumour initiation due to changes in susceptible mammary stem cell populations during development and drives the formation of more aggressive stem like tumours.

METHODS

Using a transgenic mouse model driving expression of Spy1 within the mammary gland, mammary development and stemness were assessed. These mice were intercrossed with p53 null mice to study the tumourigenic properties of Spy1 driven p53 null tumours, as well as global changes in signaling via RNA sequencing analysis.

RESULTS

We show that elevated levels of Spy1 leads to expansion of mammary stem cells, even in the presence of p53, and an increase in mammary tumour formation. Spy1-driven tumours have an increased cancer stem cell population, decreased checkpoint signaling, and demonstrate an increase in therapy resistance. Loss of Spy1 decreases tumor onset and reduces the cancer stem cell population.

CONCLUSIONS

This data demonstrates the potential of Spy1 to expand mammary stem cell populations and contribute to the initiation and progression of aggressive, breast cancers with increased cancer stem cell populations.

Stabilization of c-Myc by the atypical cell cycle regulator, Spy1, decreases efficacy of breast cancer treatments

PURPOSE

c-Myc is frequently upregulated in breast cancers, however, targeting c-Myc has proven to be a challenge. Targeting of downstream mediators of c-Myc, such as the 'cyclin-like' cell cycle regulator Spy1, may be a viable therapeutic option in a subset of breast cancer subtypes.

METHODS

Mouse mammary tumor cells isolated from MMTV-Myc mice and human breast cancer cell lines were used to manipulate Spy1 levels followed by tamoxifen or chemotherapeutic treatment with a variety of endpoints. Patient samples from TNBC patients were obtained and constructed into a TMA and stained for c-Myc and Spy1 protein levels.

RESULTS

Over time, MMTV-Myc cells show a decreased response to tamoxifen treatment with increasing levels of Spy1 in the tamoxifen-resistant cells. shRNA against Spy1 re-establishes tamoxifen sensitivity. Spy1 was found to be highly elevated in human TNBC cell and patient samples, correlating to c-Myc protein levels. c-Myc was found to be stabilized by Spy1 and knocking down Spy1 in TNBC cells shows a significant increase in response to chemotherapy treatments.

CONCLUSION

Understanding the interplay between protein expression level and response to treatment is a critical factor in developing novel treatment options for breast cancer patients. These data have shown a connection between Spy1 and c-Myc protein levels in more aggressive breast cancer cells and patient samples. Furthermore, targeting c-Myc has proven difficult, these data suggest targeting Spy1 even when c-Myc is elevated can confer an advantage to current chemotherapies.

The cyclin-like protein SPY1 overrides reprogramming induced senescence through EZH2 mediated H3K27me3

Fully differentiated cells can be reprogrammed through ectopic expression of key transcription factors to create induced pluripotent stem cells. These cells share many characteristics of normal embryonic stem cells and have great promise in disease modeling and regenerative medicine. The process of remodeling has its limitations, including a very low efficiency due to the upregulation of many antiproliferative genes, including cyclin dependent kinase inhibitors CDKN1A and CDKN2A, which serve to protect the cell by inducing apoptotic and senescent programs. Our data reveals a unique cell cycle mechanism enabling mouse fibroblasts to repress cyclin dependent kinase inhibitors through the activation of the epigenetic regulator EZH2 by a cyclin-like protein SPY1. This data reveals that the SPY1 protein is required for reprogramming to a pluripotent state and is capable of increasing reprogramming efficiency.

Cyclin-like proteins tip regenerative balance in the liver to favour cancer formation

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide. A variety of factors can contribute to the onset of this disease, including viral infection, obesity, alcohol abuse and non-alcoholic fatty liver disease (NAFLD). These stressors predominantly introduce chronic inflammation leading to liver cirrhosis and finally the onset of HCC; however, approximately 20% of HCC cases arise in the absence of cirrhosis via a poorly defined mechanism. The atypical cyclin-like protein Spy1 is capable of overriding cell cycle checkpoints, promoting proliferation and has been implicated in HCC. We hypothesize that Spy1 promotes sustained proliferation making the liver more susceptible to accumulation of deleterious mutations, leading to the development of non-cirrhotic HCC. We report for the first time that elevation of Spy1 within the liver of a transgenic mouse model leads to enhanced spontaneous liver tumourigenesis. We show that the abundance of Spy1 enhanced fat deposition within the liver and decreased the inflammatory response. Interestingly, Spy1 transgenic mice have a significant reduction in fibrosis and sustained rates of hepatocyte proliferation, and endogenous levels of Spy1 are downregulated during the normal fibrotic response. Our results provide support that abnormal regulation of Spy1 protein drives liver tumorigenesis in the absence of elevated fibrosis and, hence, may represent a potential mechanism behind non-cirrhotic HCC. This work may implicate Spy1 as a prognostic indicator and/or potential target in the treatment of diseases of the liver, such as HCC. The cyclin-like protein Spy1 enhances lipid deposition and reduces fibrosis in the liver. Spy1 also promotes increased hepatocyte proliferation and onset of non-cirrhotic hepatocellular carcinoma (HCC). Thus, Spy1 may be used as a potential target in the treatment of HCC.

MicroRNA‑125a‑5p regulates liver cancer cell growth, migration and invasion and EMT by targeting HAX1

To date, the role of hematopoietic‑substrate‑1‑associated protein X‑1 (HAX1) in liver cancer is rarely studied. The present study explored the role of HAX1 in liver cancer. The association between HAX1 expression and survival of patients with liver cancer was analyzed by a log‑rank test. The target genes for HAX1 was predicted by TargetScan and verified by a dual‑luciferase reporter assay. The protein and mRNA expressions of HAX1 in liver cancer and adjacent non‑cancerous tissues were examined by immunohistochemistry and reverse transcription‑quantitative PCR (RT‑qPCR). The transfection efficiency of HAX1, small interfering RNA against HAX1, microRNA (miR)‑125a mimics, miR‑125a inhibitor, miR‑223 mimics and miR‑223 inhibitor in liver cancer cells was determined by RT‑qPCR. The expression of HAX1, p53, VEGF, epithelial‑to‑mesenchymal transition (EMT)‑related markers (E‑cadherin, N‑cadherin and vimentin) in the cancer cells were determined by western blotting and RT‑qPCR. Cell viability, migration, invasion and colony formation rates were determined by Cell Counting Kot‑8, wound healing, Transwell and colony formation assays, respectively. The results showed that high expression of HAX1 in liver cancer was found relate to poor prognosis in patients with liver cancer, and upregulation of HAX1 expression in liver cancer tissues was related to lower overall survival. miR‑125a‑5p directly binds to HAX1. Upregulation of miR‑125a‑5p expression inhibited cell viability, migration, invasion and colony formation of SK‑Hep1 cells and reduced the expression of HAX1, VEGF, N‑cadherin and vimentin, but increased cell apoptosis and the expression of p53 and E‑cadherin. However, the effects miR‑125a‑5p upregulation were partially reversed by SK‑Hep1 cells with HAX1 overexpression. Downregulated miR‑125a‑5p in SNU‑387 cells produced opposite effects, which was partially reversed by HAX silencing. In conclusion, miR‑125a‑5p suppresses liver cancer growth via targeting HAX1 and concurrently modulating the expression of p53 and VEGF and EMT‑related markers.

RINGO/Speedy proteins, a family of non-canonical activators of CDK1 and CDK2

Cyclin-dependent kinases (CDKs) require the binding to a regulatory subunit to acquire enzymatic activity, and cyclins are the canonical CDK activators. However, there are specific situations in which CDKs can be activated by non-cyclin proteins that are less characterized. This review focuses on the family of RINGO/Speedy proteins, which have no sequence amino acid homology to cyclins but can bind to and activate CDK1 and CDK2. Interestingly, RINGO/Speedy proteins can activate CDKs under conditions in which CDK-cyclin complexes would not be active, and there is evidence that RINGO/Speedy-activated CDKs can phosphorylate different sites than the cyclin-activated CDKs. RINGO/Speedy proteins were originally described in Xenopus oocytes, but their roles in mammalian cells have also been addressed. We will summarize the properties of RINGO/Speedy proteins and how they trigger CDK activation, and discuss recent studies that characterized their physiological functions. In particular, studies using genetically modified mice have shown that RingoA, also known as Spy1, plays a key role in meiosis regulation. Emerging evidence also suggests a potential role for RingoA/Spy1 in cancer.

The atypical cyclin-like protein Spy1 overrides p53-mediated tumour suppression and promotes susceptibility to breast tumourigenesis

Background

Breast cancer is the most common cancer to affect women and one of the leading causes of cancer-related deaths. Proper regulation of cell cycle checkpoints plays a critical role in preventing the accumulation of deleterious mutations. Perturbations in the expression or activity of mediators of cell cycle progression or checkpoint activation represent important events that may increase susceptibility to the onset of carcinogenesis. The atypical cyclin-like protein Spy1 was isolated in a screen for novel genes that could bypass the DNA damage response. Clinical data demonstrates that protein levels of Spy1 are significantly elevated in ductal and lobular carcinoma of the breast. We hypothesized that elevated Spy1 would override protective cell cycle checkpoints and support the onset of mammary tumourigenesis.

Methods

We generated a transgenic mouse model driving expression of Spy1 in the mammary epithelium. Mammary development, growth characteristics and susceptibility to tumourigenesis were studied. In vitro studies were conducted to investigate the relationship between Spy1 and p53.

Results

We found that in the presence of wild-type p53, Spy1 protein is held ‘in check’ via protein degradation, representing a novel endogenous mechanism to ensure protected checkpoint control. Regulation of Spy1 by p53 is at the protein level and is mediated in part by Nedd4. Mutation or abrogation of p53 is sufficient to allow for accumulation of Spy1 levels resulting in mammary hyperplasia. Sustained elevation of Spy1 results in elevated proliferation of the mammary gland and susceptibility to tumourigenesis.

Conclusions

This mouse model demonstrates for the first time that degradation of the cyclin-like protein Spy1 is an essential component of p53-mediated tumour suppression. Targeting cyclin-like protein activity may therefore represent a mechanism of re-sensitizing cells to important cell cycle checkpoints in a therapeutic setting.

Expression profile and potential functional differentiation of the Speedy/RINGO family in mice

As novel cyclin-dependent kinase (CDK) activators, Speedy/RINGO (hereafter named Speedy) proteins can directly regulate the cell cycle of vertebrates by binding to and activating various CDKs. Previous studies have shown that Speedy genes are highly associated with different types of cancer and other diseases. However, Speedy genes have not been systematically identified in mice, and their function and expression profiles remain elusive, which greatly hinders the functional and mechanistic study of Speedy genes in vivo. Here, we comprehensively identified Speedy genes in the mouse genome. Phylogenetic analysis showed that the Speedy gene family should be divided into three subfamilies, rather than the previously reported two subfamilies. Mice have two of the three subfamilies of Speedy genes, namely, subfamilies A and E. Speedy subfamily C genes have been lost from the mouse genome. By combining experimental and bioinformatics approaches, we found that the genes from subfamilies A and E have different expression profiles, indicating their functional divergence, which was also consistent with the phylogenetic results. The genes belonging to subfamily E showed only slightly different expression profiles, indicating their similar functions. Coexpression network analysis showed that the genes coexpressed with mouse Speedy genes were primarily enriched in reproduction-related mechanisms and there were significant functional differences between genes from subfamilies A and E, further demonstrating functional differentiation. In summary, we provide a comprehensive landscape (from evolution to expression and function) of the Speedy family in mice; we also demonstrate that Speedy genes mainly participate in reproduction-related mechanisms and that they have undergone functional differentiation in mice.

High Spy1 expression predicts poor prognosis in colorectal cancer

Background

Spy1 (SPDYA) is a new discovered cell cycle protein capable of promoting cell proliferation dependent on cyclin-dependent kinase-2 activation. However, to the best of our knowledge, the expression of Spy1 in colorectal cancer (CRC) tissues remains virtually unknown.

Materials and methods

In this retrospective study, we investigated the mRNA and protein expression levels of Spy1 in CRC tissues and corresponding non-cancerous tissues with the analyses of quantitative real-time polymerase chain reaction, western blotting, and immunohistochemistry. In our research, the prognostic significances of Spy1 expression were further explored by univariate and multivariate survival analyses of 203 patients who were followed up.

Results

The results demonstrated that the levels of Spy1 mRNA were significantly higher in CRC tissues compared with corresponding non-cancerous tissues (p=0.0002). The results of immunohistochemistry demonstrated that the expressions of Spy1 were significantly associated with clinicopathological parameters, including T stage (χ²=7.126, p=0.028) and TNM stage (χ²=9.461, p=0.009). Kaplan-Meier analysis results indicated that high Spy1 expression (HR=2.573, p<0.001) and TNM stage (HR=1.494, p=0.011) were independent factors to predict poor prognosis for patients with CRC.

Conclusion

We concluded that high Spy1 expression is significantly associated with unfavorable prognosis in CRC and could serve as a potential prognostic marker in clinical diagnosis of CRC.

The cyclin-like protein, SPY1, regulates the ERα and ERK1/2 pathways promoting tamoxifen resistance

The Ras/Raf/MEK/ERK pathway conveys growth factor and mitogen signalling to control the phosphorylation of a plethora of substrates regulating proliferation, survival, and migration. The Ras signalling pathway is frequently associated with poor prognosis and drug resistance in various cancers including those of the blood, breast and prostate. Activation of the downstream effector ERK does not always occur via a linear cascade of events; complicating the targeting of this pathway therapeutically. This work describes a novel positive feedback loop where the cell cycle regulatory factor Spy1 (RINGO; gene SPDYA) activates ERK1/2 in a MEK-independent fashion. Spy1 was originally isolated for the ability to stimulate Xenopus oocyte maturation via a MAPK-signalling pathway and is known to override apoptosis triggered by the DNA damage response. We demonstrate that mammalian Spy1-mediated ERK activation increases ligand-independent phosphorylation and activation of estrogen receptor α, correlating with a decrease in tamoxifen sensitivity. This could define a novel druggable mechanism driving proliferation and resistance in select cancers.

Structural basis of divergent cyclin-dependent kinase activation by Spy1/RINGO proteins

Cyclin-dependent kinases (Cdks) are principal drivers of cell division and are an important therapeutic target to inhibit aberrant proliferation. Cdk enzymatic activity is tightly controlled through cyclin interactions, posttranslational modifications, and binding of inhibitors such as the p27 tumor suppressor protein. Spy1/RINGO (Spy1) proteins bind and activate Cdk but are resistant to canonical regulatory mechanisms that establish cell-cycle checkpoints. Cancer cells exploit Spy1 to stimulate proliferation through inappropriate activation of Cdks, yet the mechanism is unknown. We have determined crystal structures of the Cdk2-Spy1 and p27-Cdk2-Spy1 complexes that reveal how Spy1 activates Cdk. We find that Spy1 confers structural changes to Cdk2 that obviate the requirement of Cdk activation loop phosphorylation. Spy1 lacks the cyclin-binding site that mediates p27 and substrate affinity, explaining why Cdk-Spy1 is poorly inhibited by p27 and lacks specificity for substrates with cyclin-docking sites. We identify mutations in Spy1 that ablate its ability to activate Cdk2 and to proliferate cells. Our structural description of Spy1 provides important mechanistic insights that may be utilized for targeting upregulated Spy1 in cancer.

Direct interactions with both p27 and Cdk2 regulate Spy1-mediated proliferation in vivo and in vitro

Families of cyclin-like proteins have emerged that bind and activate cyclin dependent kinases (Cdk)s, directing the phosphorylation of noncanonical Cdk substrates. One of these proteins, Spy1, has demonstrated the unique ability to directly bind and activate both Cdk1 and Cdk2, as well as binding and promoting the degradation of at least one Cdk inhibitor, p27(Kip1). Spy1 accelerates somatic cell growth and proliferation and is implicated in a number of human cancers including the breast, brain and liver. Herein we isolate key residues mediating the direct interaction with p27. We use mutants of Spy1 to determine the physiological role of direct interactions with distinct binding partners Cdk2 and p27. We demonstrate that disrupting the direct interaction with either Spy1 binding partner decreased endogenous activity of Cdk2, as well as Spy1-mediated proliferation. However, only the direct interaction with p27 was essential for Spy1-mediated effects on p27 stability. In vivo neither mutation completely prevented tumorigenesis, although each mutation slowed the rate of Spy1-mediated tumorigenesis and decreased overall tumor volumes. This work supports the conclusion that direct interaction with both p27 and Cdk2 contribute to Spy1-mediated effects on cell growth. It is important to elucidate the dynamics of these interactions and to consider these data when assessing functional outcomes.

HES5 promotes cell proliferation and invasion through activation of STAT3 and predicts poor survival in hepatocellular carcinoma

OBJECTIVES

HES5 is a member of the basic helix-loop-helix (bHLH) family of transcription factors, and involved in cell differentiation and proliferation in a variety of tissues other than HCC. Therefore, we have characterized HES5 and investigated its role during hepatocarcinogenesis.

METHODS

We first examined the expression of HES5 in eight paired frozen HCC and adjacent noncancerous liver tissues by Western blot. Immunohistochemistry was performed to confirm our results in 58 HCC samples and evaluated the relativity between the expression of HES5 and clinicopathological variables and estimated the prognostic significance. Moreover, Western blot examined the expression of downstream proteins by siRNA HES5. Flow cytometer assay was performed to investigate the role of HES5 in the process of HCC.

RESULTS

We found that HES5 was upregulated in HCC specimens. The data showed that high expression of HES5 was tightly associated with histological grade (P<0.01) and metastasis (P<0.01), and positively correlated with proliferation marker Ki-67 (P<0.01). Moreover, the results show that abnormal expression of HES5 influences cell growth and cell cycle of HCC cell lines. Furthermore, HES5 knockdown resulted in the reduction of p-STAT3.

CONCLUSION

These results suggested that suppression of the HES5 leading to inhibition of proliferation may be one of the mechanisms against HCC.

Spy1 Protein Mediates Phosphorylation and Degradation of SCG10 Protein in Axonal Degeneration

Axon loss is a destructive consequence of a wide range of neurological diseases without a clearly defined mechanism. Recent data demonstrate that SCG10 is a novel axonal maintenance factor and that rapid SCG10 loss after injury requires JNK activity; how JNK induces degradation of SCG10 is not well known. Here we showed that SCG10 was a binding partner of Spy1, a Speedy/RINGO family protein, which participated in cellular response to sciatic nerve injury. During the early stage of axonal injury, Spy1 expression was inversely correlated with SCG10. Spy1 mediated SCG10 phosphorylation and degradation partly in a JNK-dependent manner. Inhibition of Spy1 attenuated SCG10 phosphorylation and delayed injury-induced axonal degeneration. Taken together, these data suggest that Spy1 is an important regulator of SCG10 and can be targeted in future axo-protective therapeutics.

Management of hepatocellular carcinoma: Predictive value of immunohistochemical markers for postoperative survival

Hepatocellular carcinoma (HCC) accounts for over 90% of all primary liver cancers. With an ever increasing incidence trend year by year, it has become the third most common cause of death from cancer worldwide. Hepatic resection is generally considered to be one of the most effective therapies for HCC patients, however, there is a high risk of recurrence in postoperative HCC. In clinical practice, there exists an urgent need for valid prognostic markers to identify patients with prognosis, hence the importance of studies on prognostic markers in improving the prediction of HCC prognosis. This review focuses on the most promising immunohistochemical prognostic markers in predicting the postoperative survival of HCC patients.

Identification of Gem as a new candidate prognostic marker in hepatocellular carcinoma

GTP binding protein overexpressed in skeletal muscle (Gem) is a Ras-related protein whose expression is induced in several cell types upon activation by extracellular stimuli. To investigate the potential roles of Gem in hepatocellular carcinoma (HCC), expression of Gem was examined in human HCC samples. Western blot analysis showed that compared with primary human hepatocytes and adjacent noncancerous tissue, significant down-regulation of Gem was found in HCC cells and tumor tissues. In addition, immunohistochemical analysis of Gem expression was investigated in 108 specimens of HCC tissues. Clinicopathological data were collected to analyze the association with Gem expression. Expression of Gem was significantly negatively correlated with histological grade (P=0.001), tumor size (P=0.020), and vascular invasion (P=0.005), and Gem was also negatively correlated with proliferation marker Ki-67 (P<0.01). More importantly, the Kaplan-Meier survival curves analysis revealed that low expression of Gem was associated with poor prognosis in HCC patients. Univariate analysis showed that Gem expression was associated with poor prognosis (P=0.006). Multivariate analysis indicated that Gem expression was an independent prognostic marker for HCC (P=0.007). Finally, serum starvation and release experiments showed that Gem expression was negatively related with cell proliferation. In the conclusion, our results suggested that down regulation of Gem expression was involved in the pathogenesis of hepatocellular carcinoma, and it might be a favorable independent prognostic parameter for HCC.

Chaperonin containing TCP1, subunit 8 (CCT8) is upregulated in hepatocellular carcinoma and promotes HCC proliferation

The development of molecular pathogenesis of hepatocellular carcinoma (HCC) is complex and involves alterations in the expression and conformation of assorted oncoproteins and tumor suppressors. Chaperonin containing TCP1 (CCT) is a cytolic molecular chaperone complex that is required for the correct folding of numerous proteins. In this study, we investigated a possible involvement of CCT subunit 8 (CCT8) in HCC development. Immunohistochemical analysis was performed in 102 human HCC samples. High CCT8 expression was detected in clinical HCC samples compared with adjacent noncancerous tissues. The univariate and multivariate survival analyses were also performed to determine their prognostic significance. Western blot confirmed the high expression of CCT8 in HCC compared with adjacent normal tissue. Moreover, the biological significance of the aberrant expression of CCT8 was investigated in HCC cell lines. Expression of CCT8 was correlated directly with the histologic grades and tumor size of HCC and high expression of CCT8 was associated with a poor prognosis. CCT8 depletion by siRNA inhibited cell proliferation and blocked S-phase entry in HuH7 cells. These results suggested that CCT8 might be an oncogene and participate in HCC cell proliferation. These findings provide a potential therapeutic strategy for the treatment of HCC.

Increased expression of glycinamide ribonucleotide transformylase is associated with a poor prognosis in hepatocellular carcinoma, and it promotes liver cancer cell proliferation

Glycinamide ribonucleotide transformylase (GART) is a folate-dependent enzyme in the de novo purine pathway that has been the target of antineoplastic intervention for almost 2 decades. Until now, its expression and functional significance in hepatocellular carcinoma (HCC) have been unclear. We demonstrated by Western blotting that the expression of GART was markedly up-regulated in HCC patients. Immunohistochemistry staining was used to determine the expression of GART in HCC and adjacent nontumor tissues from 96 patients. Increased expression of GART correlated positively with the histologic grade (P = .001), tumor size (P = .043), number of tumorous nodes (P = .020), and intrahepatic metastases (P = .031), suggesting a role for GART in the progression of HCC. Patients with higher GART expression had a much worse overall survival rate than those with low expression (P = .002). Furthermore, multivariate analysis showed that GART expression was an independent predictor of overall survival (hazard ratio, 2.265; 95% confidence interval, 1.335-3.842; P = .002). Depletion of GART by small interfering RNA inhibited cell proliferation and blocked S-phase and mitotic entry in cultured HepG2 and BEL-7404 cells. Western blot analyses showed that GART depletion decreased the proliferating cell nuclear antigen concentration. Collectively, our clinical and in vitro data indicate that GART expression may be one of the causative factors for a poor prognosis in HCC.

Polycomb group oncogene RING1 is over-expressed in non-small cell lung cancer

Ring finger protein 1 (RING1) have recently been reported to be related to aggressive tumor features in Prostate Cancer and urothelial carcinoma of the bladder. However, the role of RING1 in non-small-cell lung cancer (NSCLC) tumorigenesis has never been elucidated. So we aimed at investigating the potential role of RING1 in NSCLC. RING1 expression was evaluated by Immunoblot in 8 paired fresh lung cancer tissues and immunohistochemistry on 69 paraffin-embedded sections from 2006 to 2009. Furthermore, flow-cytometry and RNA interference were performed to analyse the role of RING1 in A549 cells. We showed that the expression level of RING1 was significant increased in lung cancer as compared with the adjacent normal tissue. High expression level of RING1 was associated with TNM stage (P = 0.013), and RING1 was positively related with proliferation marker Ki67 (P < 0.05). Moreover, RING1 knockdown induces growth suppression of human lung cancer cells through G1/S cell cycle phase arrest in vitro. Kaplan-Meier survival curves showed that high expression level of RING1 was associated with poor prognosis (P = 0.03). On the basis of these results, we suggested that RING1 protein expression may be a favorable independent prognostic parameter for non-small cell lung cancer.

Suppression of KIF3B expression inhibits human hepatocellular carcinoma proliferation

BACKGROUND

Human hepatocellular carcinoma (HCC) is one of the most common fatal cancers and an important health problem worldwide, but its mechanism is still unclear. Microtubule (MT) kinesin motor proteins orchestrate a variety of cellular processes (e.g. mitosis, motility and organelle transportation) and have been involved in human carcinogenesis. KIF3B, the kinesin superfamily of proteins (KIFs), plays an important role in the regulation of mitotic progression.

AIM

The expression of KIF3B and its involvement in HCC was investigated.

METHODS

Western blot and immunohistochemistry were used to measure the expression of KIF3B protein in HCC and adjacent non-tumorous tissues in 57 patients and Cell Counting Kit-8 to analyze the effects of growth and interference of KIF3B in the cell cycle process.

RESULTS

KIF3B protein level was increased in HCC tissues compared with the adjacent non-tumorous tissues. It was significantly associated with histological differentiation, tumor size, the level of alpha fetal protein (AFP) and proliferation marker Ki-67. Over-expression of KIF3B was correlated with poor survival. Following release of HepG2 cells from serum starvation, the expression of KIF3B was up-regulated. Furthermore, suppression of KIF3B not only decreased cancer cell growth but also induced apoptosis of cells.

CONCLUSIONS

Our results suggested that KIF3B expression was upregulated in HCC tumor tissues and proliferating HCC cells, and an increased KIF3B expression was associated with poor overall survival. KIF3B over-expression is involved in the pathogenesis of hepatocellular carcinoma and may serve as a potential therapeutic target for human HCC.

MIF4G domain containing protein regulates cell cycle and hepatic carcinogenesis by antagonizing CDK2-dependent p27 stability

The CDK inhibitor p27(kip1) plays crucial roles in cell cycle regulation and cancer progression. Through yeast two-hybrid screening, we identified MIF4G domain containing protein (MIF4GD) as a novel binding partner for p27. The association of MIF4GD and p27 was verified using immunoprecipitation and glutathione S-transferase (GST) pull-down assays. Interaction with MIF4GD led to the stabilization of p27 both in the nucleus and in the cytoplasm in hepatocellular carcinoma (HCC) cells as a result of suppressed phosphorylation of p27 by CDK2 at threonine187. Serum stimulation decreased the levels of MIF4GD and p27 simultaneously. In addition, MIF4GD overexpression resulted in increased p27 levels and reduced cell proliferation, while knockdown of MIF4GD promoted cell cycle progression with decreased p27 levels in cells. Furthermore, overexpression of MIF4GD reduced colony formation and inhibited xenograft tumor growth in nude mice. Finally, we found that both MIF4GD and p27 were expressed at low levels in HCC tissues compared to non-cancerous tissues, and that low expression levels of MIF4GD and p27 were associated with significantly worse prognosis in HCC patients. Our results suggest that MIF4GD is a potential regulator of p27-dependent cell proliferation in HCC. These findings provide a rational framework for the development of potential HCC therapy by targeting the MIF4GD-p27 interaction.

Upregulated expression of CAP1 is associated with tumor migration and metastasis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers that exhibits high incidences of intrahepatic metastasis and tumor recurrence. Adenylate cyclase-associated protein 1 (CAP1), a protein involved in the regulation of actin filaments, was recently reported to play a role in cell motility and the pathology of pancreatic cancer. In this study, we examined a potential role of CAP1 in HCC progression, and found that CAP1 was overexpressed in HCC specimens compared with adjacent noncancerous liver tissues by Western blot analysis and real-time PCR assay. Further, immunohistochemical analysis in 107 HCC specimens revealed that overexpression of CAP1 was closely correlated only with tumor metastasis, but not with other clinicopathologic parameters. Univariate and multivariate survival analyses showed that CAP1 could be an independent prognostic factor for patients' survival. In addition, immunofluorescent assay demonstrated that CAP1 was colocalized with actin in the leading edge of lamellipodium in HCC cells. Importantly, knocking-down the expression of CAP1 using small interfering RNA (siRNA) targeting CAP1 led to impaired migration of HCC cells. Collectively, our results indicated that upregulated expression of CAP1 might contribute heavily to the metastasis of HCC.

Increased α-tubulin1b expression indicates poor prognosis and resistance to chemotherapy in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer deaths worldwide. It is important to understand molecular mechanisms of HCC progression and to develop clinically useful biomarkers for the disease.

AIM

We aimed to investigate the possible involvement of α-tubulin1b (TUBA1B) in HCC pathology.

METHODS

Tissue specimens were obtained from 114 HCC patients during hepatectomy. Immunohistochemistry and western blot analysis were used to detect TUBA1B expression in HCC tissues and cell lines. TUBA1B was knocked down in HCC cells by siRNA transfection. CCK-8 assay and flow cytometry were applied to determine cell proliferation and cell cycle progression, respectively. The efficacy of paclitaxel chemotherapy was evaluated by plate colony formation assay.

RESULTS

TUBA1B was higher expressed in HCC tumor tissues than in adjacent nontumor tissues. TUBA1B and Ki-67 expressions were positively related to each other, and both their expressions were significantly associated with histological grade of HCC patients. Univariate and multivariate survival analyses revealed that TUBA1B was a significant predictor for overall survival of HCC patients. TUBA1B expression was increased in HCC cells during the G1- to S-phase transition. TUBA1B knockout in HCC cells inhibited cell proliferation, and attenuated resistance to paclitaxel.

CONCLUSIONS

Our results indicated that TUBA1B expression was upregulated in HCC tumor tissues and proliferating HCC cells, and an increased TUBA1B expression was associated with poor overall survival and resistance to paclitaxel of HCC patients.

Expression of SGTA correlates with prognosis and tumor cell proliferation in human hepatocellular carcinoma

To investigate the potential role of small glutamine-rich TPR-containing protein A (SGTA) in hepatocarcinogenesis, immunohistochemistry and Western blot were performed to detect the expression of SGTA in clinical Hepatocellular carcinoma (HCC) samples, adjacent nontumorous liver tissues and HCC cell lines. In addition, expression of SGTA was correlated with clinicopathological variables and univariate and multivariate survival analyses were performed to determine the prognostic significance. Moreover, the biological significance of the aberrant expression of SGTA was investigated in vitro. Both immunohistochemistry evaluation and Western blot analyses demonstrated that SGTA was overexpressed in HCC tissues compared with adjacent nontumorous liver tissues. Expression of SGTA directly correlated with the histological grades of HCC and high expression of SGTA was associated with a poor prognosis. SGTA depletion by siRNA inhibited cell proliferation, blocked S-phase and mitotic entry in Huh7 cells. Western blot analyses showed that SGTA depletion decreased cyclin A and cyclin B levels. Taken together, owing to overexpression of SGTA in HCC and its important role in predicting poor prognosis and the development of HCC, SGTA could be a potential prognostic marker and therapeutic target of HCC.

High SKIP expression is correlated with poor prognosis and cell proliferation of hepatocellular carcinoma

Ski-interacting protein (SKIP) is a transcriptional cofactor distinct from other cofactors and involved in the regulation of many cancer-related proteins. This study investigated the expression of SKIP and its potential clinical and biological significances in hepatocellular carcinoma (HCC). Immunohistochemistry and Western blot were performed to detect the expression of SKIP in clinical HCC samples and adjacent noncancerous tissues. In addition, expression of SKIP was correlated with clinicopathological variables, and univariate and multivariate survival analyses were performed to determine the prognostic significance. Moreover, the biological significance of the aberrant expression of SKIP was investigated in vitro. High SKIP expression was detected in clinical HCC samples compared with adjacent noncancerous tissues. Expression of SKIP correlated directly with the histological grades of HCC and high expression of SKIP was associated with a poor prognosis. SKIP depletion by small interfering RNA inhibited cell proliferation and blocked S phase entry in HepG2 cells. Owing to overexpression of SKIP in HCC tissues and its important role in predicting poor prognosis and the development of HCC, SKIP could be a potential prognostic marker and therapeutic target of HCC.

Temporal-spatial expressions of Spy1 in rat sciatic nerve after crush

As a novel cell cycle protein, Spy1 enhances cell proliferation, promotes the G1/S transition as well as inhibits apoptosis in response to UV irradiation. Spy1 levels are tightly regulated during mammary development, and overexpression of Spy1 accelerates tumorigenesis in vivo. But little is known about the role of Spy1 in the pathological process of damage and regeneration of the peripheral nervous system. Here we established a rat sciatic nerve crush (SNC) model to examine the spatiotemporal expression of Spy1. Spy1 expression was elevated gradually after sciatic nerve crush and peaked at day 3. The alteration was due to the increased expression of Spy1 in axons and Schwann cells after SNC. Spy1 expression correlated closely with Schwann cells proliferation in sciatic nerve post injury. Furthermore, Spy1 largely localized in axons in the crushed segment, but rarely co-localized with GAP43. These findings suggested that Spy1 participated in the pathological process response to sciatic nerve injury and may be associated with Schwann cells proliferation and axons regeneration.

Expression of Spy1 protein in human non-Hodgkin's lymphomas is correlated with phosphorylation of p27 Kip1 on Thr187 and cell proliferation

Aberrations in cell cycle control are often observed in tumors and might even be necessary in tumor development. Spy1, a novel cell cycle regulatory protein, can control cell progression and survival through the atypical activation of cyclin-dependent kinases (CDKs). In this progression, the phosphorylation of p27(Kip1) at Thr187 by CDK2 was shown to be a chief role. In this study, we studied 183 human specimens including reactive lymphoid and Non-Hodgkin's Lymphomas (NHLs) tissues. Immunohistochemistry (IHC) analysis suggested that Spy1 and pThr187-p27 were overexpressed in NHLs. The expression of Spy1 was positively related to pThr187-p27 and proliferation marker Ki-67 expression. In a multivariate analysis, high Spy1 and pThr187-p27 expressions were showed to be associated with poor prognosis in NHLs. While in vitro, following release of Jurkat cells from serum starvation, the expression of Spy1 was upregulated, as well as pThr187-p27 and CDK2. And an increased interaction between Spy1 and pThr187-p27 was demonstrated at 4 h after serum stimulation. Additionally, transfecting cells with Spy1-siRNA could diminish the expression of pThr187-p27 and arrest cell growth. Our results suggest that Spy1 may be a possible prognostic indicator in NHLs, and it was correlated with phosphorylation of p27(Kip1) on Thr187. These findings provide a rational framework for further development of Spy1 inhibitors as a novel class of anti-tumor agents.

Genome-wide analysis of DNA methylation identifies novel cancer-related genes in hepatocellular carcinoma

Aberrant DNA methylation has been implicated in the development of hepatocellular carcinoma (HCC). Our aim was to clarify its molecular mechanism and to identify useful biomarkers by screening for DNA methylation in HCC. Methylated CpG island amplification coupled with CpG island microarray (MCAM) analysis was carried out to screen for methylated genes in primary HCC specimens [hepatitis B virus (HBV)-positive, n = 4; hepatitis C virus (HCV)-positive, n = 5; HBV/HCV-negative, n = 7]. Bisulfite pyrosequencing was used to analyze the methylation of selected genes and long interspersed nuclear element (LINE)-1 in HCC tissue (n = 57) and noncancerous liver tissue (n = 50) from HCC patients and in HCC cell lines (n = 10). MCAM analysis identified 332, 342, and 259 genes that were methylated in HBV-positive, HCV-positive, and HBV/HCV-negative HCC tissues, respectively. Among these genes, methylation of KLHL35, PAX5, PENK, and SPDYA was significantly higher in HCC tissue than in noncancerous liver tissue, irrespective of the hepatitis virus status. LINE-1 hypomethylation was also prevalent in HCC and correlated positively with KLHL35 and SPDYA methylation. Receiver operating characteristic curve analysis revealed that methylation of the four genes and LINE-1 strongly discriminated between HCC tissue and noncancerous liver tissue. Our data suggest that aberrant hyper- and hypomethylation may contribute to a common pathogenesis mechanism in HCC. Hypermethylation of KLHL35, PAX, PENK, and SDPYA and hypomethylation of LINE-1 could be useful biomarkers for the detection of HCC.

The cyclin-like protein Spy1/RINGO promotes mammary transformation and is elevated in human breast cancer

Background

Spy1 is a novel 'cyclin-like' activator of the G1/S transition capable of enhancing cell proliferation as well as inhibiting apoptosis. Spy1 protein levels are tightly regulated during normal mammary development and forced overexpression in mammary mouse models accelerates mammary tumorigenesis.

Methods

Using human tissue samples, cell culture models and in vivo analysis we study the implications of Spy1 as a mediator of mammary transformation and breast cancer proliferation.

Results

We demonstrate that this protein can facilitate transformation in a manner dependent upon the activation of the G2/M Cdk, Cdk1, and the subsequent inhibition of the anti-apoptotic regulator FOXO1. Importantly, we show for the first time that enhanced levels of Spy1 protein are found in a large number of human breast cancers and that knockdown of Spy1 impairs breast cancer cell proliferation.

Conclusions

Collectively, this work supports that Spy1 is a unique activator of Cdk1 in breast cancer cells and may represent a valuable drug target and/or a prognostic marker for subsets of breast cancers.