Synuclein gamma inhibits the mitotic checkpoint function and promotes chromosomal instability of breast cancer cells

Cyclic-NDGA Effectively Inhibits Human γ-Synuclein Fibrillation, Forms Nontoxic Off-Pathway Species, and Disintegrates Preformed Mature Fibrils

Parkinson's disease arises from protein misfolding, aggregation, and fibrillation and is characterized by LB (Lewy body) deposits, which contain the protein α-synuclein (α-syn) as their major component. Another synuclein, γ-synuclein (γ-syn), coexists with α-syn in Lewy bodies and is also implicated in various types of cancers, especially breast cancer. It is known to seed α-syn fibrillation after its oxidation at methionine residue, thereby contributing in synucleinopathy. Despite its involvement in synucleinopathy, the search for small molecule inhibitors and modulators of γ-syn fibrillation remains largely unexplored. This work reveals the modulatory properties of cyclic-nordihydroguaiaretic acid (cNDGA), a natural polyphenol, on the structural and aggregational properties of human γ-syn employing various biophysical and structural tools, namely, thioflavin T (ThT) fluorescence, Rayleigh light scattering, 8-anilinonaphthalene-1-sulfonic acid binding, far-UV circular dichroism (CD), Fourier transform infrared spectroscopy (FTIR) spectroscopy, atomic force microscopy, ITC, molecular docking, and MTT-toxicity assay. cNDGA was observed to modulate the fibrillation of γ-syn to form off-pathway amorphous species that are nontoxic in nature at as low as 75 μM concentration. The modulation is dependent on oxidizing conditions, with cNDGA weakly interacting (Kd ∼10-5 M) with the residues at the N-terminal of γ-syn protein as investigated by isothermal titration calorimetry and molecular docking, respectively. Increasing cNDGA concentration results in an increased recovery of monomeric γ-syn as shown by sodium dodecyl sulfate and native-polyacrylamide gel electrophoresis. The retention of native structural properties of γ-syn in the presence of cNDGA was further confirmed by far-UV CD and FTIR. In addition, cNDGA is most effective in suppression of fibrillation when added at the beginning of the fibrillation kinetics and is also capable of disintegrating the preformed mature fibrils. These findings could, therefore, pave the ways for further exploring cNDGA as a potential therapeutic against γ-synucleinopathies.

In Pancreatic Adenocarcinoma Alpha-Synuclein Increases and Marks Peri-Neural Infiltration

α-Synuclein (α-syn) is a protein involved in neuronal degeneration. However, the family of synucleins has recently been demonstrated to be involved in the mechanisms of oncogenesis by selectively accelerating cellular processes leading to cancer. Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal human cancers, with a specifically high neurotropism. The molecular bases of this biological behavior are currently poorly understood. Here, α-synuclein was analyzed concerning the protein expression in PDAC and the potential association with PDAC neurotropism. Tumor (PDAC) and extra-tumor (extra-PDAC) samples from 20 patients affected by PDAC following pancreatic resections were collected at the General Surgery Unit, University of Pisa. All patients were affected by moderately or poorly differentiated PDAC. The amount of α-syn was compared between tumor and extra-tumor specimen (sampled from non-affected neighboring pancreatic areas) by using in situ immuno-staining with peroxidase anti-α-syn immunohistochemistry, α-syn detection by using Western blotting, and electron microscopy by using α-syn-conjugated immuno-gold particles. All the methods consistently indicate that each PDAC sample possesses a higher amount of α-syn compared with extra-PDAC tissue. Moreover, the expression of α-syn was much higher in those PDAC samples from tumors with perineural infiltration compared with tumors without perineural infiltration.

Cellular and molecular mechanisms of perineural invasion of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignant disease with a unique tumor microenvironment surrounded by an interlaced network of cancer and noncancerous cells. Recent works have revealed that the dynamic interaction between cancer cells and neuronal cells leads to perineural invasion (PNI), a clinical pathological feature of PDAC. The formation and function of PNI are dually regulated by molecular (e.g., involving neurotrophins, cytokines, chemokines, and neurotransmitters), metabolic (e.g., serine metabolism), and cellular mechanisms (e.g., involving Schwann cells, stromal cells, T cells, and macrophages). Such integrated mechanisms of PNI not only support tumor development, growth, invasion, and metastasis but also mediate the formation of pain, all of which are closely related to poor disease prognosis in PDAC. This review details the modulation, signaling pathways, detection, and clinical relevance of PNI and highlights the opportunities for further exploration that may benefit PDAC patients.

A Novel Ruthenium-Fluvastatin Complex Downregulates SNCG Expression to Modulate Breast Carcinoma Cell Proliferation and Apoptosis via Activating the PI3K/Akt/mTOR/VEGF/MMP9 Pathway

Breast cancer is the most common cause of malignancy and cancer-related morbidity and death worldwide that requests effective and safe chemotherapy. Evaluation of metallodrug-based anticancer agents and statins as chemotherapeutics with fewer side effects is a largely unexplored research field. Synthesis and characterization of the ruthenium-fluvastatin complex were achieved using multiple spectroscopic techniques and thus further examined to evaluate its chemotherapeutic prospects in both MDA-MB-231 and MCF-7 cancer lines and eventually in vivo models of DMBA-induced mammary carcinogenesis in rodents. Our studies indicate that the metal and ligand chelation was materialized by the ligand's functional groups of carbonyl (=O) oxygen and hydroxyl (-OH), and the complex has been observed to be crystalline and able to chelate with CT-DNA. The complex was able to reduce cell proliferation and activate apoptotic events in breast carcinoma cell lines MCF-7 and MDA-MB-231. In addition, the complex was able to modify p53 expressions to interfere with apoptosis in the carcinoma of the breast, stimulated by the intrinsic apoptotic path assisted by Bcl2 and Bax in vivo, yet at the same point, controlling the PI3K/Akt/mTOR/VEGF pathway, as obtained from western blotting, correlates with the MMP9-regulated tumor mechanisms. Our research reveals that ruthenium-fluvastatin chemotherapy may disrupt, rescind, or interrupt breast carcinoma progression by modifying intrinsic apoptosis as well as the antiangiogenic cascade, thereby taking the role of a potential candidate in cancer therapy for the immediate future.

Emerging Mechanisms and Treatment Progress on Liver Metastasis of Colorectal Cancer

Colorectal cancer is currently the third largest malignant tumor in the world, with high new cases and high mortality. Metastasis is one of the most common causes of death of colorectal cancer, of which liver metastasis is the most fatal. Since the beginning of the Human Genome Project in 2001, people have gradually recognized the 3 billion base pairs that make up the human genome, of which only about 1.5% of the nucleic acid sequences are used for protein coding, including proto-oncogenes and tumor suppressor genes. A large number of differences in the expression of proto-oncogenes and tumor suppressor genes have also been found in the study of colorectal cancer, which proves that they are also actively involved in the progression of colorectal cancer and promote the occurrence of liver metastasis. Except for 1.5% of the coding sequence, the rest of the nucleic acid sequence does not encode any protein, which is called non-coding RNA. With the deepening of research, genome sequences without protein coding potential that were originally considered “junk sequences” may have important biological functions. Many years of studies have found that a large number of abnormal expression of ncRNA in colorectal cancer liver metastasis, indicating that ncRNA plays an important role in it. To explore the role and mechanism of these coding sequences and non-coding RNA in liver metastasis of colorectal cancer is very important for the early diagnosis and treatment of liver metastasis of colorectal cancer. This article reviews the coding genes and ncRNA that have been found in the study of liver metastasis of colorectal cancer in recent years, as well as the mechanisms that have been identified or are still under study, as well as the clinical treatment of liver metastasis of colorectal cancer.

Silencing of BCSG1 with specific siRNA via nanocarriers for breast cancer treatment

Breast cancer is the most common cancer diagnosed in women worldwide. The current treatments for breast cancer, including surgery, radiotherapy and chemotherapy aim to destroy cancer cells, whereas they also cause damage to normal tissues and cells. Thus, an effective, safe and specific breast cancer treatment is urgently needed. The breast cancer-specific gene 1 (BCSG1) has been shown to be specific for the development of breast cancer and is a target for breast cancer diagnosis and treatment. It is expected to silence the expression of BCSG1 at the gene level for the purpose of treating breast cancer. The effect of RNAi technology on silencing target genes is comparable to gene knockout and has been widely used in animal experiments and plant genetic research. In the field of cancer therapy, numerous investigators have used siRNAs to specifically inhibit target genes, demonstrating that siRNAs can treat cancers at the molecular level. However, the delivery of siRNAs into humans needs to overcome multiple physiological barriers, limiting the clinical applications of siRNAs. This review focuses on the application of BCSG1 gene, siRNAs in cancer treatments, and the nanocarrier delivery system of siRNAs. The potential application and research value of BCSG1-specific siRNA in the treatment of breast cancer are discussed.

Guanidinoneomycin-maleimide molecular transporter: synthesis, chemistry and cellular uptake

Guanidinoglycosides are a class of non-cytotoxic molecular transporters capable of delivering high molecular weight bioactive cargos into cells at low nanomolar concentrations. Efficient bioconjugation with guanidinoglycosides has been previously demonstrated by utilizing a guanidinoneomycin decorated with a reactive but also unstable N-hydroxysuccinimmide ester-containing linker. Herein we report the synthesis, chemistry, and application of a new, stable guanidinoneomycin derivative armed with a highly specific maleimide moiety which allows for thiol-maleimide click chemistry, a highly popular bioconjugation strategy, widening the field of application of these intriguing and useful delivery vehicles.

Silencing of Synuclein-γ inhibits human cervical cancer through the AKT signaling pathway

BACKGROUND

Synuclein-γ has been demonstrated to be highly expressed in various human cancers including cervical cancer, and has been shown to play a critical role in tumor aggressiveness. We aimed to investigate the role of Synuclein-γ in human cervical cancer in vitro and in vivo.

METHOD

Reverse transcription-quantitative polymerase chain reaction assay and Western blot assay were used to detect the mRNA and protein expression, respectively. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and colony formation assay were performed to measure the viabilities of cancer cells. Flow cytometry assay was used to detect the cell cycle and apoptosis. Moreover, an animal experiment was performed to evaluate the biological behavior of Synuclein-γ in vivo.

RESULTS

In the current study, we found that Synuclein-γ was obviously over-expressed in cervical cancer tissues compared to the adjacent non-cancer tissues. Cervical cancer cells transfected with Synuclein-γ siRNA demonstrated significant inhibition of cancer proliferation (P < 0.01), cell cycle arrest at G0/G1 phase, and cell apoptosis (P < 0.05). Moreover, down-regulation of Synuclein-γ significantly inhibited cervical cancer growth in vivo. In addition, protein levels of AKT, c-Myc and Cyclin D1 were much lower in the Synuclein-γ siRNA-treated groups than that in the control group.

CONCLUSIONS

Synuclein-γ inhibition reduced cervical cancer tumor growth through the AKT pathway. This effect represented a therapeutic opportunity and provided a novel target for cervical cancer treatment.

α-Synuclein misfolding and aggregation: Implications in Parkinson's disease pathogenesis

α-Synuclein (α-Syn) has been extensively studied for its structural and biophysical properties owing to its pathophysiological role in Parkinson's disease (PD). Lewy bodies and Lewy neurites are the pathological hallmarks of PD and contain α-Syn aggregates as their major component. It was therefore hypothesized that α-Syn aggregation is actively associated with PD pathogenesis. The central role of α-Syn aggregation in PD is further supported by the identification of point mutations in α-Syn protein associated with rare familial forms of PD. However, the correlation between aggregation propensities of α-Syn mutants and their association with PD phenotype is not straightforward. Recent evidence suggested that oligomers, formed during the initial stages of aggregation, are the potent neurotoxic species causing cell death in PD. However, the heterogeneous and unstable nature of these oligomers limit their detailed characterization. α-Syn fibrils, on the contrary, are shown to be the infectious agents and propagate in a prion-like manner. Although α-Syn is an intrinsically disordered protein, it exhibits remarkable conformational plasticity by adopting a range of structural conformations under different environmental conditions. In this review, we focus on the structural and functional aspects of α-Syn and role of potential factors that may contribute to the underlying mechanism of synucleinopathies. This information will help to identify novel targets and develop specific therapeutic strategies to combat Parkinson's and other protein aggregation related neurodegenerative diseases.

Computational Study on the Role of γ-Synuclein in Inhibiting the α-Synuclein Aggregation

BACKGROUND

α-Synuclein (αS) is the precursor protein present in Lewy Bodies that helps in the formation of highly ordered amyloid fibrils that is associated with the occurrence of Parkinson's disease, a neuro-degenerative disorder. Many reports have now been focused on finding the probable targets to weaken this debilitating disease. Recently γ-synuclein (γS), a presynaptic protein, was highlighted to inhibit the aggregation propensity of αS both in vivo and in vitro. However the nature, location and specificity of molecular interactions existing between the αS and γS is not known in spite of the potential importance of γS as an inhibitor of αS.

OBJECTIVE

To understand the inhibition of αS aggregation by γS at the molecular level.

METHODS

Umbrella sampling method was used along with molecular dynamics simulation to investigate the conformational dynamics, degree of association and molecular interaction between the monomeric units in the αS/γS hetero-dimer.

RESULTS AND DISCUSSION

The dissociation energy barrier for αS/γS hetero-dimer was found to be higher than αS/αS homo-dimer. αS can therefore readily form a hetero-dimer by combining with γS than forming a homo-dimer. We also observed strong transient interactions involving hydrogen bonds, salt-bridges and non-bonded contacts between the monomeric units in αS/γS hetero-dimer.

CONCLUSION

Our findings suggest that γS may inhibit the aggregation propensity of αS.

siRNA Targeting of the SNCG Gene Inhibits the Growth of Gastric Carcinoma SGC7901 Cells in vitro and in vivo by Downregulating the Phosphorylation of AKT/ERK

The aim of the study was to evaluate the effects of synuclein-γ (SNCG) silencing on gastric cancer SGC7901 cells and to elucidate the associated mechanisms. pGCSIL-lentiviral siRNA targeting of the SNCG gene was employed to inhibit SNCG expression. Several experiments such as quantitative real-time PCR, Western blotting, MTT, colony formation, migration assay, and flow cytometry were performed to investigate the biological behavior of infected SGC7901 cells. BALB/c nude mice were used as tumor xenograft models to assess the effects of SNCG silencing on tumor growth. Western blot analysis was carried out to determine the relative levels of AKT, p-AKT, ERK, and p-ERK expression. Our results showed that SNCG was overexpressed in SGC7901 cells as compared to normal gastric mucosal epithelial cells. SGC7901 cells transfected with SNCG siRNA demonstrated significantly decreased gastric cancer growth (p < 0.01), reduced cell migration, cell cycle arrest in the G0/G1 phase, promoted tumor cell apoptosis (p < 0.01), and inhibited tumorigenesis in xenograft animal models. Western blot analysis indicated that the protein levels of p-AKT and p-ERK were much lower in the SNCG siRNA group than in the control groups. The results of the present study suggest that SNCG siRNA plays a significant role in the proliferation, migration, and tumorigenesis of gastric cancer by downregulating the phosphorylation of AKT and ERK. RNA interference-mediated silencing of SNCG may provide an opportunity to develop a novel treatment strategy for gastric cancer.

BCSG1 siRNA delivered by lentiviral vector suppressed proliferation and migration of MDA-MB-231 cells

Breast cancer-specific gene 1 (BCSG1), also referred to as γ-synuclein (SNCG), is highly expressed in human infiltrating breast carcinomas, but not in normal or benign breast tissue. The present study aimed to evaluate the effects of BCSG1 siRNA delivered by lentiviral vector on breast cancer cells and investigate the underlying mechanisms. BCSG1 RNAi lentiviral vector was constructed and transfected into MDA-MB-231 cells. BCSG1 mRNA levels were determined by quantitative polymerase chain reaction analysis. Cell proliferation, migration and apoptosis were evaluated by using the cell counting kit‑8, Transwell assay and flow cytometry, respectively, followed by western blotting to determine the relative levels of AKT, extracellular signal‑regulated kinase (ERK), p-AKT and p-ERK expression. BCSG1 mRNA levels were significantly reduced in MDA-MB‑231 cells following transfection of BCSG1 siRNA delivered by lentiviral vector. Cell migration and proliferation were significantly decreased and the cell cycle was arrested. Western blot analysis indicated that the protein levels of p-AKT and p-ERK were significantly lower in the BCSG1 siRNA-treated groups compared with the control and negative control groups. Therefore, BCSG1 siRNA delivered by lentiviral vector was able to significantly reduce BCSG1 expression, suppress cell migration and proliferation, possibly through the reduction of the protein levels of p-AKT and p-ERK.

Preparation of chitosan‑silicon dioxide/BCSG1‑siRNA nanoparticles to enhance therapeutic efficacy in breast cancer cells

Breast cancer is one of the most serious diseases, posing threats to women's physical and mental health. Gene therapy has been gradually regarded as an important part of tumor therapeutics. In the present study, the breast cancer‑specific gene 1‑small interference RNA (BCSG1‑siRNA) plasmid was designed, then encapsulated by chitosan‑silicon dioxide nanometer carriers. The results demonstrated a successful encapsulation of BCSG1‑siRNA in chitosan‑silicon dioxide nanoparticles (encapsulation efficiency exceeded 90%). BCSG1‑siRNA was released slowly (the release rate was almost 30% after 24 h). The cytotoxic effect on MCF‑7 cells was enhanced by increasing the concentration of nanoparticle (the proliferation rate was reduced to 13.4±5.3% and apoptosis rate was increased to 71.5±6.8%). Therefore, the materials presented in the current study acted as successful gene carriers and exhibited significant antitumor effects in breast cancer cells.

Synuclein-γ in uterine serous carcinoma impacts survival: An NRG Oncology/Gynecologic Oncology Group study

BACKGROUND

Synuclein-γ (SNCG) is highly expressed in advanced solid tumors, including uterine serous carcinoma (USC). The objective of the current study was to determine whether SNCG protein was associated with survival and clinical covariates using the largest existing collection of USCs from the Gynecologic Oncology Group (GOG-8023).

METHODS

High-density tissue microarrays (TMAs) of tumor tissues from 313 patients with USC were stained by immunohistochemistry for SNCG, p53, p16, FOLR1, pERK, pAKT, ER, PR, and HER2/neu. Associations of SNCG and other tumor markers with overall and progression-free survival were assessed using log-rank tests and Cox proportional-hazards models, which also were adjusted for age, race, and stage.

RESULTS

The overall survival at 5 years was 46% for women with high SNCG expression and 62% for those with low SNCG expression (log-rank P = .021; hazard ratio [HR], 1.31; 95% confidence interval [CI], 0.91-1.9 in adjusted Cox model). The progression-free survival rate at 5 years was worse for women who had high SNCG expression, at 40%, compared with 56% for those who had low SNCG expression (log-rank P = .0081; HR, 1.36; 95% CI, 0.96-1.92 in adjusted Cox model). High levels of both p53 and p16 were significantly associated with worse overall survival (p53: HR, 4.20 [95% CI, 1.54-11.45]; p16: HR, 1.95 [95% CI, 1.01-3.75]) and progression-free survival (p53: HR, 2.16 [95% CI, 1.09-4.27]; p16: HR, 1.53 [95% CI, 0.87-2.69]) compared with low levels.

CONCLUSIONS

This largest collection of USCs to date demonstrates that SNCG was associated with poor survival in univariate analyses. SNCG does not predict survival outcome independent of p53 and p16 in models that jointly consider multiple markers. Cancer 2017;123:1144-1155. © 2016 American Cancer Society.

Overexpression of synuclein-γ predicts lack of benefit from radiotherapy for breast cancer patients

Background

Although radiotherapy following mastectomy was demonstrated to reduce the recurring risk and improve the prognosis of patients with breast cancer, it is also notorious for comprehensive side effects, hence only a selected group of patients can benefit. Therefore, the screening of molecular markers capable of predicting the efficacy of radiotherapy is essential.

Methods

We have established a cohort of 454 breast cancer cases and selected 238 patients with indications for postoperative radiotherapy. Synuclein-γ (SNCG) protein levels were assessed by immunohistochemistry, and SNCG status was retrospectively correlated with clinical features and survival in patients treated or not treated with radiotherapy. Gene Set Enrichment Analysis (GSEA) and survival analysis for online datasets were also performed for further validation.

Results

Among patients that received radiotherapy (82/238), those demonstrating positive SNCG expression had a 55.0 month shorter median overall survival (OS) in comparison to those demonstrating negative SNCG expression (78.4 vs. 133.4 months, log rank χ² = 16.13; p < 0.001). Among the patients that received no radiotherapy (156/238), SNCG status was not correlated with OS (log rank χ² = 2.40; p = 0.121). A COX proportional hazard analysis confirmed SNCG as an independent predictor of OS, only for patients who have received radiotherapy. Similar results were also obtained for distant metastasis-free survival (DMFS). A GSEA analysis indicated that SNCG was strongly associated with genes related to a radiation stress response. A survival analysis was performed with online databases consisting of breast cancer, lung cancer, and glioblastoma and further confirmed SNCG’s significance in predicting the survival of patients that have received radiotherapy.

Conclusion

A positive SNCG may serve as a potential marker to identify breast cancer patients who are less likely to benefit from radiotherapy and may also be extended to other types of cancer. However, the role of SNCG in radiotherapy response still needs to be further validated in randomized controlled trials prior to being exploited in clinical practice.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2750-y) contains supplementary material, which is available to authorized users.

A novel conditional gene silencing method using a tumor-specific and heat-inducible siRNA system

RNAi technology is an invaluable tool for investigating gene function. However, the non-temporal and non-spatial control is the primary limitation, which leads to siRNA leakiness and off-target effects. In this study, we inserted three kinds of HSE into tumor specific promoter hTERT, which aims to construct a temperature-inducible and tumor-specific RNAi plasmid vector. In our system, the expression of mature siRNA is tightly controlled by the heat shock-inducible and tumor-specific promoters. From the expression level of RNA and protein, we determined the efficiency of the inducible siRNA system by targeting SNCG gene in HepG2 and MCF-7 cells. Results showed that the controllable siRNA system could be induced to initiate siRNA expression by heat-induce. The silencing effect of SNCG is on a relative low level (10 %) at 37 °C, while it is significantly increased to 50 or 60 % after heat inducing at 43 °C. This new conditional siRNA system provides a novel approach to drive the siRNA expression by heat-inducible and tumor-specific promoter.

γ-Synuclein Expression Is a Malignant Index in Oral Squamous Cell Carcinoma

Dysregulation of γ-synuclein (SNCG) has been reported in many cancers; however, its role in cancer development is still controversial. Here, we examined the potential involvement of DNA methylation in regulating SNCG and its role in oral squamous cell carcinoma (OSCC). We used 8 OSCC cell lines to investigate SNCG methylation and expression. SNCG methylation was examination by methylation-specific polymerase chain reaction and bisulfate sequencing. Cells showing a high degree of SNCG methylation were treated with 5-aza (methylation inhibitor), and changes in their methylation and expression profiles were analyzed. Functional effects of SNCG in OSCC were examined by its overexpression and knockdown. Additionally, methylation and expression of SNCG in OSCC tissues were investigated and correlated with clinicopathologic features. All OSCC cells showed detectable SNCG expression at the mRNA and protein levels. Methylation-specific polymerase chain reaction and bisulfate sequencing revealed high SNCG expression in SCC25 cells with the unmethylated allele, and their 15 CpG islands were unmethylated. The methylated allele was detected only in OEC-M1 cells exhibiting low SNCG expression, and their CpG islands were partially methylated. 5-aza treatment in OEC-M1 cells attenuated methylation and restored SNCG expression. SNCG overexpression increased colony forming, migration, and invasion abilities in OEC-M1 cells. Silencing SNCG in SCC25 cells suppressed these behaviors. All 25 tumor-adjacent normal tissues were negative for SNCG immunostaining. SNCG upregulation was frequently observed in dysplastic and OSCC tissues. Positive SNCG expression was found in 45% (37 of 82) OSCC tissues. Positive SNCG expression in OSCC significantly correlated with cancer staging and lymph node metastasis. However, SNCG methylation did not correlate with its expression and clinicopathologic variables in OSCC tissues. DNA methylation may participate in regulating SNCG expression in some OSCC cells. SNCG upregulation could be involved in OSCC progression.

γ-Synuclein confers both pro-invasive and doxorubicin-mediated pro-apoptotic properties to the colon adenocarcinoma LS 174T cell line

γ-synuclein, a neuronal protein of the synuclein family, is involved in carcinogenesis. To investigate its role in colorectal cancer carcinogenesis, we overexpressed γ-synuclein in LS 174T colon adenocarcinoma cell line (termed LS 174T-γsyn). When compared with untransfected/mock transfectants, LS 174T-γsyn had higher mobility in scratch wound assay, tend to scatter more in cell-scattering assay, and had enhanced lamellipodia and filopodia formation in cell-spreading assay. Enhanced adhesion of LS 174T-γsyn to fibronectin and collagen and significantly higher proliferation rate showed that γ-synuclein was able to increase extracellular matrix interaction and promoted proliferation of LS 174T. Higher invasiveness of LS 174T-γsyn was evidenced by enhanced invasion to the bottom of the basement membrane in Boyden chamber assay. However, LS 174T-γsyn were significantly more vulnerable to doxorubicin, vincristine and hydrogen peroxide insults, via apoptotic cell death. LS 174T-γsyn also had reduced anchorage-independent growth as shown by reduced colony formation and reduced anoikis resistance. We found that overexpression of γ-synuclein confers both pro-invasive and doxorubicin-mediated pro-apoptotic properties to LS 174T, where the former was mediated through enhanced cyclic adenosine monophosphate response element binding protein (CREB) phosphorylation, while the latter involved hepatocyte growth factor (HGF) downregulation and subsequent downstream signalling pathways possibly involving extracellular signal-regulated kinases (ERK)1/2, p38α, c-Jun N-terminal kinase (JNK) pan and Signal Transducers and Activators of Transcription (STATs). This unexpected contrasting finding as compared to other similar studies on colon cancer cell lines might be correlated with the degree of tumour advancement from which the cell lines were derived from.

Combined expression of metastasis related markers Naa10p, SNCG and PRL-3 and its prognostic value in breast cancer patients

Combinations of multiple biomarkers representing distinct aspects of metastasis may have better prognostic value for breast cancer patients, especially those in late stages. In this study, we evaluated the protein levels of N-α-acetyltransferase 10 protein (Naa10p), synuclein-γ (SNCG), and phosphatase of regenerating liver-3 (PRL-3) in 365 patients with breast cancer by immunohistochemistry. Distinct prognostic subgroups of breast cancer were identified by combination of the three biomarkers. The Naa10p+SNCG-PRL-3- subgroup showed best prognosis with a median distant metastasis-free survival (DMFS) of 140 months, while the Naa10p-SNCG+PRL-3+ subgroup had the worst prognosis with a median DMFS of 60.5 months. Multivariate analysis indicated Naa10p, SNCG, PRL-3, and the TNM classification were all independent prognostic factors for both DMFS and overall survival (OS). The three biomarker combination of Naa10p, SNCG and PRL-3 performed better in patients with lymph node metastasis, especially those with more advanced tumors than other subgroups. In conclusion, the combined expression profile of Naa10p, SNCG and PRL-3, alone or in combination with the TNM classification system, may provide a precise estimate of prognosis of breast cancer patients.

Unconventional secretion of synuclein-γ promotes tumor cell invasion

Synuclein-γ (SNCG) is a chaperone protein and exists mainly in the cytoplasm. SNCG confers chemoresistance, and is a potential unfavorable biomarker for multiple types of cancer. Our previous work demonstrated that SNCG could be detected in the serum of cancer patients and the medium of cultured cancer cells, but the mechanism of SNCG secretion and its biological roles are unknown. Here, we showed that SNCG levels in the culture medium were positively correlated with cancer cell densities and the concentrations of fetal bovine serum added. SNCG secretion was unaffected by brefeldin A, an inhibitor of the classic protein transport pathway, but was antagonized by exosome inhibitor, lysosome inhibitor, ABC transporter inhibitor, and phosphatidylinositide 3-kinase inhibitor, and knockdown of Rab27a. Ultracentrifugation fractionation revealed that intracellular SNCG was present as both free and vesicle-associated forms, but that the extracellular SNCG was mainly free. The results of reciprocal coimmunoprecipitation experiments showed an interaction between SNCG and flotillin-2, a marker of exosomes and lipid rafts. Moreover, we demonstrated that SNCG, both secreted from tumor cells and exogenously added, markedly promoted cancer cell migration and invasion, but had no effect on noncancerous cells. These findings suggest that SNCG is actively secreted by cancer cells via an unconventional secretion pathway and contributes to aggressive phenotypes of cancer cells.

siRNA-Mediated Suppression of Synuclein γ Inhibits MDA-MB-231 Cell Migration and Proliferation by Downregulating the Phosphorylation of AKT and ERK

Purpose

Synuclein-γ (SNCG), which was initially identified as breast cancer specific gene 1, is highly expressed in advanced breast cancers, but not in normal or benign breast tissue. This study aimed to evaluate the effects of SNCG siRNA-treatment on breast cancer cells and elucidate the associated mechanisms.

Methods

Vectors containing SNCG and negative control (NC) siRNAs were transfected into MDA-MB-231 cells; mRNA levels were determined by real-time polymerase chain reaction. Cell proliferation was evaluated using the MTT assay, cell migration was assessed by the Transwell assay, apoptosis and cell cycle analyses were conducted with the flow cytometer, and Western blot analysis was performed to determine the relative levels of AKT, ERK, p-AKT, and p-ERK expression.

Results

SNCG mRNA levels were significantly reduced in MDA-MB-231 cells transfected with SNCG siRNA. Our results indicate that in SNCG siRNA-treated cells, cell migration and proliferation decreased significantly, apoptosis was induced, and the cell cycle was arrested. Western blot analysis indicated that the protein levels of p-AKT and p-ERK were much lower in the SNCG siRNA-treated groups, than in the control and NC groups.

Conclusion

SNCG siRNA could decrease the migration and proliferation of breast cancer cells by downregulating the phosphorylation of AKT and ERK.

Synuclein gamma protects HER2 and renders resistance to Hsp90 disruption

Hsp90 is an important driver of stabilization and activation of several oncogenic proteins in many key pathways in oncogenesis, including HER2. The present study demonstrated that synuclein gamma (SNCG) prevents the protein degradation and protects the function of HER2 in the condition when the function of Hsp90 is blocked. Disruption of Hsp90 resulted in a significant degradation of HER2 and the loss of activity. However, SNCG completely recovered Hsp90 disruption-mediated losses of HER2 and the function. SNCG bound to HER2 in the presence and absence of Hsp90. Specifically, the C-terminal (Gln106-Asp127) of SNCG bound to the loop connecting αC helix and β4 sheet of the kinase domain of HER2. SNCG renders resistance to 17-AAG-induced tumor suppression in tumor xenograft. Crossing SNCG transgenic mice with HER2 mice stimulated HER2-induced tumor growth and rendered resistance to Hsp90 disruption. The present study indicates that SNCG protects Hsp90 client protein of HER2, and renders resistance to Hsp90 disruption.

The function of α-synuclein

Human genetics has indicated a causal role for the protein α-synuclein in the pathogenesis of familial Parkinson's disease (PD), and the aggregation of synuclein in essentially all patients with PD suggests a central role for this protein in the sporadic disorder. Indeed, the accumulation of misfolded α-synuclein now defines multiple forms of neural degeneration. Like many of the proteins that accumulate in other neurodegenerative disorders, however, the normal function of synuclein remains poorly understood. In this article, we review the role of synuclein at the nerve terminal and in membrane remodeling. We also consider the prion-like propagation of misfolded synuclein as a mechanism for the spread of degeneration through the neuraxis.

SILAC-based proteomic analysis to investigate the impact of amyloid precursor protein expression in neuronal-like B103 cells

Alzheimer's disease (AD) is the most prevalent form of dementia in the elderly. Amyloid plaque formation through aggregation of the amyloid beta peptide derived from amyloid precursor protein (APP) is considered one of the hallmark processes leading to AD pathology; however, the precise role of APP in plaque formation and AD pathogenesis is yet to be determined. Using stable isotope labeling by amino acids in cell culture (SILAC) and MS, protein expression profiles of APP null, rat neuronal-like B103 cells were compared to B103-695 cells that express the APP isoform, APP-695. A total of 2979 unique protein groups were identified among three biological replicates and significant protein expression changes were identified in a total of 102 nonredundant proteins. Some of the top biological functions associated with the differentially expressed proteins identified include cellular assembly, organization and morphology, cell cycle, lipid metabolism, protein folding, and PTMs. We report several novel biological pathways influenced by APP-695 expression in neuronal-like cells and provide additional framework for investigating altered molecular mechanisms associated with APP expression and processing and contribution to AD pathology.

Synuclein-γ suppression mediated by RNA interference inhibits the clonogenicity and invasiveness of MCF-7 cells

The aim of the present study was to investigate the effects of synuclein-γ (SNCG) downregulation by RNA interference (RNAi) on the clonogenicity and invasiveness of MCF-7 breast cancer cells. This study used four pairs of SNCG-specific siRNAs which were designed and cloned into the pGPU6 plasmid for introduction into an MCF-7 cell line. The SNCG knockdown efficacies of the four siRNAs were compared using the reverse transcription polymerase chain reaction (RT-PCR) and immunocytochemistry. The cells' clonogenic and invasive phenotypes were examined with clonogenic and Boyden chamber assays. In comparison with the non-specific siRNA and empty vector controls, all four SNCG siRNAs were observed to significantly inhibit SNCG expression at the mRNA and protein levels (F=481.06, P<0.001; F=147.42, P<0.0001). SNCG suppression mediated by RNAi successfully inhibited the clonogenicity (P=0.002) and invasiveness (P<0.001) of transfected MCF-7 cells. According to the results of the present study, we concluded that SNCG suppression mediated by RNAi significantly suppressed SNCG expression at the mRNA and protein levels, suggesting that SNCG suppression mediated by an RNAi strategy may become a novel approach for treating advanced breast cancer.

Detection of tumor cell-specific mRNA in the peripheral blood of patients with breast cancer—evaluation of several markers with real-time reverse transcription-PCR

It is widely known that cells from epithelial tumors, e.g., breast cancer, detach from their primary tissue and enter blood circulation. We show that the presence of circulating tumor cells (CTCs) in samples of patients with primary and metastatic breast cancer can be detected with an array of selected tumor-marker-genes by reverse transcription real-time PCR. The focus of the presented work is on detecting differences in gene expression between healthy individuals and adjuvant and metastatic breast cancer patients, not an accurate quantification of these differences. Therefore, total RNA was isolated from blood samples of healthy donors and patients with primary or metastatic breast cancer after enrichment of mononuclear cells by density gradient centrifugation. After reverse transcription real-time PCR was carried out with a set of marker genes (BCSP, CK8, Her2, MGL, CK18, CK19). B2M and GAPDH were used as reference genes. Blood samples from patients with metastatic disease revealed increased cytokine gene levels in comparison to normal blood samples. Detection of a single gene was not sufficient to detect CTCs by reverse transcription real-time PCR. Markers used here were selected based on a recent study detecting cancer cells on different protein levels. The combination of such a marker array leads to higher and more specific discovery rates, predominantly in metastatic patients. Identification of CTCs by PCR methods may lead to better diagnosis and prognosis and could help to choose an adequate therapy.

Neural protein gamma-synuclein interacting with androgen receptor promotes human prostate cancer progression

Background

Gamma-synuclein (SNCG) has previously been demonstrated to be significantly correlated with metastatic malignancies; however, in-depth investigation of SNCG in prostate cancer is still lacking. In the present study, we evaluated the role of SNCG in prostate cancer progression and explored the underlying mechanisms.

Methods

First, alteration of SNCG expression in LNCaP cell line to test the ability of SNCG on cellular properties in vitro and vivo whenever exposing with androgen or not. Subsequently, the Dual-luciferase reporter assays were performed to evaluate whether the role of SNCG in LNCaP is through AR signaling. Last, the association between SNCG and prostate cancer progression was assessed immunohistochemically using a series of human prostate tissues.

Results

Silencing SNCG by siRNA in LNCaP cells contributes to the inhibition of cellular proliferation, the induction of cell-cycle arrest at the G1 phase, the suppression of cellular migration and invasion in vitro, as well as the decrease of tumor growth in vivo with the notable exception of castrated mice. Subsequently, mechanistic studies indicated that SNCG is a novel androgen receptor (AR) coactivator. It interacts with AR and promotes prostate cancer cellular growth and proliferation by activating AR transcription in an androgen-dependent manner. Finally, immunohistochemical analysis revealed that SNCG was almost undetectable in benign or androgen-independent tissues prostate lesions. The high expression of SNCG is correlated with peripheral and lymph node invasion.

Conclusions

Our data suggest that SNCG may serve as a biomarker for predicting human prostate cancer progression and metastasis. It also may become as a novel target for biomedical therapy in advanced prostate cancer.

γ-Synuclein interacts with phospholipase Cβ2 to modulate G protein activation

Phospholipase Cβ2 (PLC β2) is activated by G proteins and generates calcium signals in cells. PLCβ2 is absent in normal breast tissue, but is highly expressed in breast tumors where its expression is correlated with the progression and migration of the tumor. This pattern of expression parallels the expression of the breast cancer specific gene protein 1 which is also known as γ-synuclein. The cellular function of γ-synuclein and the role it plays in proliferation are unknown. Here, we determined whether γ-synuclein can interact with PLCβ2 and affect its activity. Using co-immunprecitation and co-immunofluorescence, we find that in both benign and aggressive breast cancer cell lines γ-synuclein and PLCβ2 are associated. In solution, purified γ-synuclein binds to PLCβ2 with high affinity as measured by fluorescence methods. Protease digestion and mass spectrometry studies show that γ-synuclein binds to a site on the C-terminus of PLCβ2 that overlaps with the Gαq binding site. Additionally, γ-synuclein competes for Gαq association, but not for activators that bind to the N-terminus (i.e. Rac1 and Gβγ). Binding of γ-synuclein reduces the catalytic activity of PLCβ2 by mechanism that involves inhibition of product release without affecting membrane interactions. Since activated Gαq binds more strongly to PLCβ2 than γ-synuclein, addition of Gαq(GTPγS) to the γ-synuclein -PLCβ2 complex allows for relief of enzyme inhibition along with concomitant activation. We also find that Gβγ can reverse γ-synuclein inhibition without dissociating the γ-synuclein- PLCβ2- complex. These studies point to a role of γ-synuclein in promoting a more robust G protein activation of PLCβ2.

Combined phenotype of 4 markers improves prognostic value of patients with colon cancer

INTRODUCTION

Combination of multiple biomarkers representing distinct aspects of tumor biology will have a better prognostic value. This study was to identify prognostic subgroups of colon adenocarcinoma by combined analysis of synuclein-gamma (SNCG), a human homologue of piwi (Hiwi), phosphatase of regenerating liver-3 (PRL-3), arrest-defective protein 1, homolog A (ARD1) and clinicopathologic features in 225 colon adenocarcinoma specimens.

METHODS

Immunohistochemistry for 4 tumor markers was performed in whole tissue sections from 225 colon adenocarcinoma patients with complete clinicopathologic data and up to 10-year follow-up. The immunohistochemical expression patterns were examined individually and in multimarker combinations. Univariate and multivariate analyses were performed to identify independent predictive markers of poor outcome.

RESULTS

With the tumor marker positive rate [32.0% (62/225) for SNCG; 76.9% (173/225) for combined SNCG/Hiwi/PRL-3/ARD1] and the detecting accuracy [61.9% (252/407) for SNCG; 82.6% (336/407) for combined SNCG/Hiwi/PRL-3/ARD1] increasing, incremental value of combined SNCG/Hiwi/PRL-3/ARD1 (P < 0.001; hazard ratios (HR), 3.2) to poor outcome was found. Stratified by lymph node, Hiwi alone (P = 0.004; HR, 3.2) led to poor outcome in patients without lymph node metastasis (LN-), and SNCG (P < 0.001; HR, 2.5) had independently poor prognostic value for patients with lymph node metastasis (LN+).

CONCLUSIONS

Multimarker phenotypes improved tumor positive rate, detecting accuracy and prognostic value. In addition, a subgroup of more aggressive tumors can be identified by evaluating Hiwi level in LN- cancer, and SNCG level in LN+ cancer.

Gene expression profiling and therapeutic interventions in neurodegenerative diseases: a comprehensive study on potentiality and limits

INTRODUCTION

Neurodegenerative diseases are incurable debilitating disorders of the nervous system that affect approximately 30 million people worldwide. Despite profuse efforts attempting to define the molecular mechanisms underlying neurodegeneration, many aspects of these pathologies remain elusive. The novelty of their mechanisms represents a challenge to biology, to their related biomarkers identification and drug discovery. Because of their multifactorial aspects and complexity, gene expression analysis platforms have been extensively used to investigate altered pathways during degeneration and to identify potential biomarkers and drug targets.

AREAS COVERED

This work offers an overview of the gene expression profiling studies carried out on Alzheimer's disease, Huntington's disease, Parkinson's disease and prion disease specimens. Therapeutic approaches are also discussed.

EXPERT OPINION

Although many therapeutic approaches have been tested, some of them acting on several altered cellular pathways, no effective cures for these neurodegenerative diseases have been identified. Microarray technology must be associated with functional proteomics and physiology in an effort to identify specific and selective biomarkers and druggable targets, thus allowing the successful discovery of disease-modifying therapeutic treatments.

An exploratory analysis of γ-synuclein expression in endometrioid endometrial cancer

OBJECTIVE

This study aims to investigate the expression of γ-synuclein in endometrioid endometrial carcinoma and assess if the γ-synuclein expression correlates with the aggression of the tumour and its prognostic value in endometrioid endometrial carcinoma.

DESIGN

This retrospective study evaluated (60) specimens of the primary untreated endometrioid endometrial carcinoma and (12) normal endometrium tissues, and the expression of γ-synuclein was checked by immunohistochemistry. The correlation between γ-synuclein expression and the clinicopathological features of patients with endometrioid endometrial carcinoma was analysed, and SPSS V.13.0 software was used for statistical analysis.

RESULTS

The expression of γ-synuclein was positive in 48.3% (29/60) endometrioid endometrial carcinomas compared with the control group, and the difference was significant (p=0.001). The expression level of γ-synuclein in endometrioid endometrial carcinoma was closely associated with FIGO (International Federation of Gynecology and Obstetrics) stages, the depth of myometrial invasion and lymph nodes metastases (p<0.05), but not correlated with the histopathological grades, the patient's age and the expression of ER (estrogen receptor) and PR (progesterone receptor) (p>0.05). In univariate and multivariate analyses, the γ-synuclein expression was significantly associated with a shorter overall survival (95% CI 1.429 to 101.892, p=0.020).

CONCLUSIONS

This study suggests that the expression of γ-synuclein is expected to be a useful marker for endometrioid endometrial carcinoma invasion, metastasis and prognosis in endometrioid endometrial carcinoma.

Synuclein gamma predicts poor clinical outcome in colon cancer with normal levels of carcinoembryonic antigen

Background

Synuclein gamma (SNCG), initially identified as a breast cancer specific gene, is aberrantly expressed in many different malignant tumors but rarely expressed in matched nonneoplastic adjacent tissues. In this study, we investigated the prognostic potential of SNCG in colon cancer particularly in the patients with normal carcinoembryonic antigen (CEA) levels.

Methods

SNCG levels were assessed immunohistochemically in cancer tissues from 229 colon adenocarcinoma patients with a mean follow-up of 44 months. Correlations between SNCG levels and clinicopathologic features, preoperative serum CEA level, and clinical outcome were analyzed statistically using SPSS.

Results

SNCG levels in colon adenocarcinoma were closely associated with intravascular embolus and tumor recurrence but independent of preoperative serum CEA levels. SNCG expression was an independent prognostic factor of a shorter disease-free survival (DFS) and overall survival (OS) (P < 0.0001). Multivariate analysis revealed that both tissue SNCG and serum CEA were independent prognostic factors of DFS (P = 0.001, <0.0001, respectively) for 170 patients with colon adenocarcinomas. Importantly, SNCG remained a prognostic determinant of DFS and OS (P = 0.001, 0.002) for 97 patients with normal preoperative serum CEA level.

Conclusions

Our results suggest for the first time that SNCG is a new independent predicator for poor prognosis in patients with colon adenocarcinoma, including those with normal CEA levels. Combination of CEA with SNCG improves prognostic evaluation for patients with colon adenocarcinoma.

Synuclein gamma stimulates membrane-initiated estrogen signaling by chaperoning estrogen receptor (ER)-alpha36, a variant of ER-alpha

Synuclein gamma (SNCG), previously identified as a breast cancer-specific gene, is highly expressed in malignant cancer cells but not in normal epithelium. The molecular targets of SNCG during breast cancer progression have not been fully identified. Here we analyzed the effect of SNCG on stimulation of membrane-initiated estrogen signaling. While SNCG expression enhanced estrogen-induced activation of ERK1/2 and mammalian target of rapamycin, knockdown of endogenous SNCG decreased membrane-initiated estrogen signaling. SNCG functions as a molecular chaperone protein for estrogen receptor (ER)-alpha36, a membrane-based variant of ER-alpha. SNCG bound to ER-alpha36 in the presence and absence of functional molecular chaperone heat shock protein 90. Disruption of heat shock protein 90 with 17-AAG significantly reduced ER-alpha36 expression and membrane-initiated estrogen signaling. However, expression of SNCG prevented ER-alpha36 degradation and completely recovered 17-AAG-mediated down-regulation of estrogen signaling. The function of SNCG in ER-alpha36-mediated estrogen signaling is consistent with its ability to stimulate cell growth in response to estrogen. Expression of SNCG also renders tamoxifen resistance, which is consistent with the clinical observation on the association of ER-alpha36 expression and tamoxifen resistance. The present study indicates that ER-alpha36 is a new member of the ER-alpha family that mediates membrane-initiated estrogen signaling and that SNCG can replace the function of heat shock protein 90, chaperone ER-alpha36 activity, stimulate ligand-dependent cell growth, and render tamoxifen resistance.

Expression of γ-synuclein in colorectal cancer tissues and its role on colorectal cancer cell line HCT116

AIM: To investigate the expression pattern of γ-synuclein in colorectal cancer (CRC) tissues, and to study the effects of γ-synuclein on CRC cell line HCT116 biological features in vitro.

METHODS: The expression pattern of γ-synuclein was determined in 54 CRC tissues and 30 tumor-matched nonneoplastic adjacent tissues (NNAT) 5 cm away from the tumor via real-time quantitative reverse transcription PCR (RT-PCR) and immunohistochemistry. The relationship between γ-synuclein protein expression and clinicopathological factors of CRC tissues was analyzed. Three small interfering RNA (siRNA) targeting γ-synuclein mRNA plasmids were constructed and transfected into the CRC cell line HCT116. The stable cell lines were selected with G-418 for 28 d, and the biological features of these cells were examined by cell growth curve, soft agar assay, and cell migration and invasion assays in vitro.

RESULTS: The expression of γ-synuclein mRNA and protein was much higher in CRC tissue samples than in NNAT samples (P = 0.02, P = 0.036). There was a significant correlation between the γ-synuclein protein expression and clinical stage and lymph node involvement of CRC (P = 0.02, P = 0.033). In functional analysis we found that down-regulation of γ-synuclein expression in HCT116 cells could inhibit the growth, colony formation rate, and migration and invasion ability of HCT116 cells.

CONCLUSION: Increased expression of γ-synuclein in CRC tissues and the biological effects of reduced γ-synuclein expression on HCT116 cells suggest that γ-synuclein may play a positive role in the progression of CRC.

Desipramine modulation of alpha-, gamma-synuclein, and the norepinephrine transporter in an animal model of depression

The mechanisms underlying depression remain elusive. We previously determined that alpha-synuclein (alpha-Syn) modulates the activity and trafficking of the norepinephrine transporter (NET) in a manner that is dependent on its interactions with microtubules (MTs). Here we sought to determine if alpha-Syn, or the other synuclein family members, beta-synuclein (beta-Syn) and gamma-synuclein (gamma-Syn), modulate NET activity in an animal model of depression, the Wistar-Kyoto (WKY) rat. The NET-selective antidepressant desipramine (DMI) was chronically administered for 14 days to WKY rats and the strain from which it was outbred that does not show depressive-like behavior, the Wistar rat. This drug regimen induced significant behavioral improvements in the WKY, but not the Wistar rat, in the forced swim test. In WKY rats there was an overexpression of gamma-Syn which was reduced following DMI treatment. In parallel, DMI caused an increase in both alpha-Syn and NET in the frontal cortex. Frontal cortex synaptosomes from WKY rats were not sensitive to nocodazole, a compound that promotes MT destabilization. However, in WKYs treated with DMI, nocodazole induced an increase in [(3)H]-NE uptake. This trend was reversed in Wistars. Underlying these DMI-induced changes were alterations in the protein interactions between the synucleins and NET with the tubulins. These results are the first to implicate alpha-Syn or gamma-Syn in the pathophysiology of depression and suggest that targeting synucleins may provide a new therapeutic option for depression.

Aberrant expression and demethylation of gamma-synuclein in colorectal cancer, correlated with progression of the disease

Recent evidence suggests that gamma-synuclein is abnormally expressed in a high percentage of tumor tissues of diversified cancer types, but rarely expressed in tumor-matched non-neoplastic adjacent tissues (NNAT). The molecular mechanism of CpG island demethylation may underlie aberrant gamma-synuclein expression. To fully understand the roles of aberrant gamma-synuclein expression and demethylation in the development of colorectal cancer (CRC), we examined the expression and methylation status of gamma-synuclein in 67 CRC samples, 30 NNAT samples, and five CRC cell lines as well. By using reverse transcription-polymerase chain reaction (RT-PCR), western blot, and immunohistochemistry analyses, gamma-synuclein expression was detected in both HT-29 and HCT116 cells, and was much higher in CRC samples than in NNAT samples (P < 0.05). The demethylating agent, 5-aza-2 cent-deoxycytidine, can induce re-expression of gamma-synuclein in COLO205, LoVo, and SW480 cells. Unmethylated gamma-synuclein alleles were detected in HT-29, HCT116, and LoVo cells by nested methylation-specific PCR, and the demethylated status of gamma-synuclein was much higher in CRC samples than in NNAT samples by real-time quantitative methylation-specific PCR (P < 0.05). The results of genomic bisulfite DNA sequencing further confirmed that the aberrant gamma-synuclein expression in CRC was primarily attributed to the demethylation of CpG island. The protein expression and demethylation status of gamma-synuclein in 67 CRC samples correlated with clinical stage, lymph node involvement, and distant metastasis. These findings suggest an involvement of aberrant gamma-synuclein expression and demethylation in progression of CRC, especially in advanced stages.

Applications of novel monoclonal antibodies specific for synuclein-gamma in evaluating its levels in sera and cancer tissues from colorectal cancer patients

Overexpressions of synuclein-gamma (SNCG) in different cancers display stage-specific patterns. At present, appropriate anti-SNCG monoclonal antibodies (mAbs) with high specificity and affinity are unavailable for different immunoassays in clinical applications. In this study, we generated 10 mAbs against endogenous SNCG and evaluated SNCG levels in several colorectal cancer cell lines, serum samples and tumor tissues from colorectal cancer (CRC) patients. Elevated SNCG levels in cancer cell lines evaluated by a novel sandwich ELISA were consistent with data obtained from Western blot. Secreted SNCG protein levels in sera from CRC patients could be detected by the sandwich ELISA and were further confirmed by Western blot analysis following SNCG enrichment. Immunohistochemical results showed that SNCG was highly expressed in tumor cells of CRC patients, but was undetectable in the adjacent normal epithelium. Taken together, these novel anti-SNCG mAbs specifically recognized endogenous SNCG and were suitable for measuring SNCG levels in cell lysates, human serum samples, and tumor tissues. Elevated serum SNCG and overexpressed SNCG in tumor tissue from CRC patients suggest SNCG is a potential biomarker for CRC.

Advances in γ-Synuclein and progression of tumors

γ-Synuclein with strong tissue specificity, a member of the synuclein family, is mainly located in nervous system. Recently, elevated levels of γ-Synuclein was detected in various types of cancers, such as breast, ovarian, liver, gastric cancers, etc., especially in their advanced stages, which indicated loss of tissue specificity in cancer development and also suggested that γ-Synuclein might serve as a new tumor marker. Additionally, multiple pathways influence the regulation of γ-Synuclein expression. γ-Synuclein has also been shown to promote invasion and metastasis of breast and ovarian cancers and enhance caners' tolerance to some chemotherapies . Overexpression of γ-synuclein also interferes with drug-induced apoptotic responses, which makes it a potential target for treatment.

Epothilones and new analogues of the microtubule modulators in taxane-resistant disease

BACKGROUND

Microtubule-stabilising agents typified by the epothilone class of drug have demonstrated promising activity in Phase II and III clinical trials.

OBJECTIVE

Data supporting the efficacy of these agents are reviewed and their potential use in taxane-refractory disease assessed.

METHODS

Preclinical evidence assessing the role of the spindle assembly checkpoint in determining the cellular response to microtubule stabilization are presented together with clinical data documenting the efficacy of non-taxane microtubule modulators.

RESULTS/CONCLUSIONS

Evidence suggests that microtubule-stabilising agents prolong activation of the spindle assembly checkpoint which may promote cancer cell death in mitosis or following mitotic exit. A weakened spindle assembly checkpoint is associated with altered sensitivity to agents targeting the microtubule and therefore pathways of drug resistance may be shared by these cytotoxic therapies. Preliminary clinical trial data do suggest modest activity of epothilones in truly taxane-resistant patient cohorts, indicating the potential niche for these agents in a molecularly undefined patient group, potentially implicating the role of P-glycoprotein in the acquisition of taxane-resistant disease. Trial data of these antimitotic agents will be presented together with their potential role in taxane-resistant disease and the implications for future clinical trial design.

Targeting synuclein-gamma to counteract drug resistance in cancer

BACKGROUND

Expression of synuclein-gamma (SNCG) protein is elevated in the advanced stages of many types of cancers, including ovarian, lung, liver, esophagus, colon, prostate and, in particular, breast. In breast carcinoma, SNCG is causatively linked to stimulated proliferation, metastasis and drug resistance.

OBJECTIVE

To establish SNCG as a potential therapeutic target and to discuss clinical use of SNCG inhibiting peptide.

METHODS

This review focuses on the plausible mechanisms of SNCG activity, SNCG mediated drug resistance and its inhibition.

RESULTS/CONCLUSION

Evidence based research shows that the aberrant expression of SNCG has a strong correlation with breast cancer progression and poor clinical outcome. A peptide based inhibitor counters activity of SNCG, which may be developed as an adjuvant therapy.