Overexpression of hepatic prothymosin alpha, a novel marker for human hepatocellular carcinoma

First Evidence of the Expression and Localization of Prothymosin α in Human Testis and Its Involvement in Testicular Cancers

Prothymosin α (PTMA) is a phylogenetically conserved polypeptide in male gonads of Vertebrates. In Mammals, it is a ubiquitous protein, and, possessing a random-coil structure, it interacts with many other partners, in both cytoplasmic and nuclear compartments. PTMA has been widely studied during cell progression in different types of cancer because of its anti-apoptotic and proliferative properties. Here, we provided the first evidence of PTMA expression and localization in human testis and in two testicular cancers (TC): classic seminoma (CS) and Leydig cell tumor (LCT). Data showed that its protein level, together with that of proliferating cell nuclear antigen (PCNA), a cell cycle progression marker, increased in both CS and LCT samples, as compared to non-pathological (NP) tissue. Moreover, in the two-cancer tissue, a decreased apoptotic rate and an increased autophagic flux was also evidenced. Results confirmed the anti-apoptotic action of PTMA, also suggesting that it can act as a switcher from apoptosis to autophagy, to favor the survival of testicular cancer cells when they develop in adverse environments. Finally, the combined data, even if they need to be further validated, add new insight into the role of PTMA in human normal and pathological testicular tissue.

Human liver single nucleus and single cell RNA sequencing identify a hepatocellular carcinoma-associated cell-type affecting survival

BACKGROUND

Hepatocellular carcinoma (HCC) is a common primary liver cancer with poor overall survival. We hypothesized that there are HCC-associated cell-types that impact patient survival.

METHODS

We combined liver single nucleus (snRNA-seq), single cell (scRNA-seq), and bulk RNA-sequencing (RNA-seq) data to search for cell-type differences in HCC. To first identify cell-types in HCC, adjacent non-tumor tissue, and normal liver, we integrated single-cell level data from a healthy liver cohort (n = 9 non-HCC samples) collected in the Strasbourg University Hospital; an HCC cohort (n = 1 non-HCC, n = 14 HCC-tumor, and n = 14 adjacent non-tumor samples) collected in the Singapore General Hospital and National University; and another HCC cohort (n = 3 HCC-tumor and n = 3 adjacent non-tumor samples) collected in the Dumont-UCLA Liver Cancer Center. We then leveraged these single cell level data to decompose the cell-types in liver bulk RNA-seq data from HCC patients' tumor (n = 361) and adjacent non-tumor tissue (n = 49) from the Cancer Genome Atlas (TCGA) multi-center cohort. For replication, we decomposed 221 HCC and 209 adjacent non-tumor liver microarray samples from the Liver Cancer Institute (LCI) cohort collected by the Liver Cancer Institute and Zhongshan Hospital of Fudan University.

RESULTS

We discovered a tumor-associated proliferative cell-type, Prol (80.4% tumor cells), enriched for cell cycle and mitosis genes. In the liver bulk tissue from the TCGA cohort, the proportion of the Prol cell-type is significantly increased in HCC and associates with a worse overall survival. Independently from our decomposition analysis, we reciprocally show that Prol nuclei/cells significantly over-express both tumor-elevated and survival-decreasing genes obtained from the bulk tissue. Our replication analysis in the LCI cohort confirmed that an increased estimated proportion of the Prol cell-type in HCC is a significant marker for a shorter overall survival. Finally, we show that somatic mutations in the tumor suppressor genes TP53 and RB1 are linked to an increase of the Prol cell-type in HCC.

CONCLUSIONS

By integrating liver single cell, single nucleus, and bulk expression data from multiple cohorts we identified a proliferating cell-type (Prol) enriched in HCC tumors, associated with a decreased overall survival, and linked to TP53 and RB1 somatic mutations.

Overexpression of prothymosin-alpha in glioma is associated with tumor aggressiveness and poor prognosis

Prothymosin-α (PTMA), a nuclear protein, is strikingly associated with unfavorable clinical outcomes in many cancers. However, no information about its clinical relevance in glioma was available. Therefore in the present study, we evaluated the prognostic utility of this protein in a cohort of 81 glioma patients. The PTMA expression was assessed by immunohistochemical analysis, quantitative PCR, and Western blotting. Furthermore, the association of PTMA with clinicopathological features and molecular alterations were assessed in the patient cohort and validated in multiomics datasets, The Cancer Genome Atlas (TCGA; n=667) and Chinese Glioma Genome Atlas (CGGA; n=1013). We observed an increase in PTMA expression with increasing histological grades of this malignancy. PTMA immunostaining also displayed a strong positive association with the MIB-1 index. Univariate analysis revealed a superior prognostic value of PTMA to predict overall survival (OS) as compared with the routinely used markers (p53, isocitrate dehydrogenase (IDH) 1 (IDH1), α-thalassemia/intellectual disability syndrome X-linked (ATRX), and Ki-67). Interestingly, in Cox regression analysis it emerged as an independent predictor of OS (hazard ratio (HR) = 13.71, 95% CI = 5.96–31.52, P<0.0001). Thus, our results demonstrate the potential prognostic utility of PTMA in glioma which may prove useful in the management of this deadly malignancy.

Thymic function affects breast cancer development and metastasis by regulating expression of thymus secretions PTMα and Tβ15b1

Breast cancer is currently one of the most common malignant tumors in women. Our previous research found that thymic dysfunction has a certain relationship with the occurrence and development of breast cancer. In order to explore whether the functional status of thymus is related to the development and metastasis of breast cancer, we use BALB/c wild type mice (BALB wt), BALB/c nude mice (BALB nu), BALB wt mice implanted with 4T1 cells (wt 4T1), BALB nu with 4T1 (nu 4T1), D-galactose treatment wt 4T1 mice (D-Gal), Thymalfasin treatment wt 4T1 mice (Tα1), Cyclophosphamide treatment wt 4T1 mice (CTX), Doxorubicin treatment wt 4T1 mice (Dox) in the research. As a result, nu 4T1, D-Gal and DOX had earlier lung metastases. Gene chip results showed that PTMα and Tβ15b1 were the most up-regulated and down-regulated genes in thymosin-related genes, respectively. Overexpression or silencing of PTMα and Tβ15b1 genes did not affect the proliferation of 4T1 cells. PTMα gene silenced, cell migration and invasion ability enhanced, while PTMα gene overexpression, the cell invasion ability weaken. In vivo, PTMα gene overexpression promotes tumor growth and lung metastasis in the early stage, but has no significant effect in the later stage. Tβ15b1 overexpression also promotes tumor growth in the early stage, but suppresses in the later stage. Tβ15b1 gene silencing inhibits tumor lung metastasis. Thus, our findings demonstrated that thymic function affects breast cancer development and metastasis by regulating expression of thymus secretions PTMα and Tβ15b1. Our study provided new directions for breast cancer therapy.

In Vitro Immunodetection of Prothymosin Alpha in Normal and Pathological Conditions

Prothymosin alpha (ProTα) is a highly acidic polypeptide, ubiquitously expressed in almost all mammalian cells and tissues and consisting of 109 amino acids in humans. ProTα is known to act both, intracellularly, as an anti-apoptotic and proliferation mediator, and extracellularly, as a biologic response modifier mediating immune responses similar to molecules termed as "alarmins". Antibodies and immunochemical techniques for ProTα have played a leading role in the investigation of the biological role of ProTα, several aspects of which still remain unknown and contributed to unraveling the diagnostic and therapeutic potential of the polypeptide. This review deals with the so far reported antibodies along with the related immunodetection methodology for ProTα (immunoassays as well as immunohistochemical, immunocytological, immunoblotting, and immunoprecipitation techniques) and its application to biological samples of interest (tissue extracts and sections, cells, cell lysates and cell culture supernatants, body fluids), in health and disease states. In this context, literature information is critically discussed, and some concluding remarks are presented.

Expression of prothymosin α in lung cancer is associated with squamous cell carcinoma and smoking

Prothymosin α (ProTα) is a nuclear protein that serves a role in oncogenesis, by promoting proliferation and inhibiting apoptosis in various malignancies. The present study was designed to investigate ProTα expression in resected human non-small cell lung cancer to define the clinicopathological associations of ProTα-positive lung cancer. Immunohistochemical staining of ProTα was performed using tumor sample slides from 149 patients with non-small cell lung cancer, who underwent surgical resection. Association between the expression of ProTα and the following clinicopathological parameters was accessed: Age, sex, stage, lymph node involvement, pathological subtype, recurrence and cigarette smoking. A total of 85 tumors (57%) were classified as ProTα-positive lung cancer by staining intensity and 73 tumors (49%) were regarded as ProTα-positive by scoring index. The majority of patients with ProTα-positive tumors were younger (P=0.05) and had squamous cell carcinoma (P<0.01) compared with older and adenocarcinoma. Positive expression of ProTα by staining intensity was associated with a higher incidence rate of cancer recurrence (P=0.05) compared with negative ProTα expression. ProTα was also associated with cigarette smoking, particularly in the group with squamous cell carcinoma. Therefore, the present data suggested that ProTα-positive non-small cell lung cancer was associated with younger patients, squamous cell carcinoma, cigarette smoking and a higher incidence recurrence rate, subsequently indicating a subtype consisting of patients with smoking-associated inferior outcomes.

Gut microbiome disruption altered the biotransformation and liver toxicity of arsenic in mice

The mammalian gut microbiome (GM) plays a critical role in xenobiotic biotransformation and can profoundly affect the toxic effects of xenobiotics. Previous in vitro studies have demonstrated that gut bacteria have the capability to metabolize arsenic (As); however, the specific roles of the gut microbiota in As metabolism in vivo and the toxic effects of As are largely unknown. Here, we administered sodium arsenite to conventionally raised mice (with normal microbiomes) and GM-disrupted mice with antibiotics to investigate the role of the gut microbiota in As biotransformation and its toxicity. We found that the urinary total As levels of GM-disrupted mice were much higher, but the fecal total As levels were lower, than the levels in the conventionally raised mice. In vitro experiments, in which the GM was incubated with As, also demonstrated that the gut bacteria could adsorb or take up As and thus reduce the free As levels in the culture medium. With the disruption of the gut microbiota, arsenic biotransformation was significantly perturbed. Of note, the urinary monomethylarsonic acid/dimethylarsinic acid ratio, a biomarker of arsenic metabolism and toxicity, was markedly increased. Meanwhile, the expression of genes of one-carbon metabolism, including folr2, bhmt, and mthfr, was downregulated, and the liver S-adenosylmethionine (SAM) levels were significantly decreased in the As-treated GM-disrupted mice only. Moreover, As exposure altered the expression of genes of the p53 signaling pathway, and the expression of multiple genes associated with hepatocellular carcinoma (HCC) was also changed in the As-treated GM-disrupted mice only. Collectively, disruption of the GM enhances the effect of As on one-carbon metabolism, which could in turn affect As biotransformation. GM disruption also increases the toxic effects of As and may increase the risk of As-induced HCC in mice.

Prothymosin alpha expression in the vertebrate testis: a comparative review

Prothymosin alpha (PTMA) is a highly acidic, intrinsically disordered protein that was first extracted from rat thymus and characterized as an immunogenic factor but soon detected in a variety of mammalian tissues. The presence of a nuclear localization signal and the adoption of a peculiar random-coil conformation are among the reasons behind its interaction with several molecular partners, hence at this time PTMA is known to be a very conserved and widely expressed molecule, involved in numerous and diverse biological processes. Only few studies have tried to weigh its possible involvement in reproduction, specifically in male gametogenesis: first reports have suggested that PTMA might be associated with the proliferative and early-meiotic phases of mammal spermatogenesis. Some years later, a comparative project on vertebrate spermatogenesis reported the isolation, for the first time, of prothymosin in a non-mammalian species, the amphibian Pelophylax esculentus. PTMA transcript and protein are localized in the germinal compartment, from spermatocytes to spermatozoa. A congruent pattern has been highlighted in studies on the fish Torpedo marmorata and Danio rerio, and in the mammal Rattus norvegicus, in which the expression of PTMA has been found in meiotic and post-meiotic germ cells inside testicular cysts and tubules. Moreover, its presence has been confirmed in rat and human spermatozoa (associated with the acrosome); its retention in the apical region of the head after the acrosome reaction revealed a striking conservation of the pattern during phylogenesis and suggested a possible role for the protein in gametogenesis and in fertilization.

Identification of the β-catenin/JNK/prothymosin-alpha axis as a novel target of sorafenib in hepatocellular carcinoma cells

Sorafenib is a kinase inhibitor used as anticancer drug against various human tumors, including advanced hepatocellular carcinoma (HCC). β-Catenin and prothymosin alpha (PTMA) are overexpressed in HCC and other tumors. Previous studies have shown that PTMA expression modulates the response of HCC cells to sorafenib. However, the underlying mechanism of PTMA activity in this context remains unclear. We show here that sorafenib inhibits both β-catenin and PTMA in a dose-dependent manner. Silencing β-catenin reduces PTMA level and sensitizes HCC cells to sorafenib. In contrast, ectopic expression of β-catenin induces PTMA expression and cell resistance to the drug. Sorafenib inhibits PTMA expression at the transcriptional level by inhibiting the β-catenin pathway. Nucleotide deletion analysis of the PTMA gene promoter reveals that a DNA segment lying 1,500–1,600 bp upstream of the PTMA transcription start site represents an AP-1-binding site that is critical for β-catenin modulation of gene transcription in response to sorafenib. In addition, chemical inhibitors that target JNK abrogate β-catenin/AP-1 binding to the endogenous PTMA gene and reduces PTMA transcription and protein expression. Silencing of β-catenin or c-Fos induces similar effects on gene regulation and these are reversed by ectopic expression of β-catenin. Mutations in the PTMA promoter at the predicted β-catenin/AP-1 binding site partly abrogate sorafenib's effects on PTMA transcription. These results indicate that PTMA is induced by the oncoprotein β-catenin and protects HCC cells against sorafenib-induced cell death. The β-catenin/JNK/PTMA axis may thus represent a novel target for chemotherapy against HCC.

Inhibition of JNK and prothymosin-alpha sensitizes hepatocellular carcinoma cells to cisplatin

Cisplatin is a potent chemotherapeutic drug widely used for the treatment of human cancer. However, its efficacy against hepatocellular carcinoma (HCC) is poor for reasons that remain unclear. We show here that prothymosin-alpha (PTMA) is overexpressed in HCC cell lines. Silencing PTMA using short-hairpin RNA sensitizes HCC cells to cisplatin, while ectopic expression of PTMA induces cell resistance to the drug. Cisplatin inhibits both the JNK pathway and PTMA in a dose-dependent manner. Treatment with a JNK inhibitor also reduces PTMA protein stability and sensitizes HCC cells to cisplatin. Notably, the effects of PTMA silencing and JNK inhibition can be reversed by ectopic expression of PTMA. We show that PTMA silencing induces translocation of proapoptotic Bax to mitochondria and enhances cisplatin-induced cytochrome c release and caspase-9 activation. Conversely, ectopic expression of PTMA reverses these effects. Our results indicate that PTMA is positively regulated by JNK and protects HCC cells against cisplatin-induced cell death. The JNK/PTMA axis may thus represent a novel target for chemotherapy against HCC.

Subcellular dissemination of prothymosin alpha at normal physiology: immunohistochemical vis-a-vis western blotting perspective

BACKGROUND

The cell type, cell status and specific localization of Prothymosin α (PTMA) within cells seemingly determine its function. PTMA undergoes 2 types of protease proteolytic modifications that are useful in elucidating its interactions with other molecules; a factor that typifies its roles. Preferably a nuclear protein, PTMA has been shown to function in the cytoplasm and extracellularly with much evidence leaning on pathognomonic status. As such, determination of its cellular distribution under normal physiological context while utilizing varied techniques is key to illuminating prospective validation of its distinct functions in different tissues. Differential distribution insights at normal physiology would also portent better basis for further clarification of its interactions and proteolytic modifications under pathological conditions like numerous cancer, ischemic stroke and immunomodulation. We therefore raised an antibody against the C terminal of PTMA to use in tandem with available antibody against the N terminal in a murine model to explicate the differences in its distribution in brain cell types and major peripheral organs through western blotting and immunohistochemical approaches.

RESULTS

The newly generated antibody was applied against the N-terminal antibody to distinguish truncated versions of PTMA or deduce possible masking of the protein by other interacting molecules. Western blot analysis indicated presence of a truncated form of the protein only in the thymus, while immunohistochemical analysis showed that in brain hippocampus the full-length PTMA was stained prominently in the nucleus whereas in the stomach full-length PTMA staining was not observed in the nucleus but in the cytoplasm.

CONCLUSION

Truncated PTMA could not be detected by western blotting when both antibodies were applied in all tissues examined except the thymus. However, immunohistochemistry revealed differential staining by these antibodies suggesting possible masking of epitopes by interacting molecules. The differential localization patterns observed in the context of nucleic versus cytoplasmic presence as well as punctate versus diffuse pattern in tissues and cell types, warrant further investigations as to the forms of PTMA interacting partners.

Prothymosin Alpha and Immune Responses: Are We Close to Potential Clinical Applications?

The thymus gland produces soluble molecules, which mediate significant immune functions. The first biologically active thymic extract was thymosin fraction V, the fractionation of which led to the isolation of a series of immunoactive polypeptides, including prothymosin alpha (proTα). ProTα displays a dual role, intracellularly as a survival and proliferation mediator and extracellularly as a biological response modifier. Accordingly, inside the cell, proTα is implicated in crucial intracellular circuits and may serve as a surrogate tumor biomarker, but when found outside the cell, it could be used as a therapeutic agent for treating immune system deficiencies. In fact, proTα possesses pleiotropic adjuvant activity and a series of immunomodulatory effects (eg, anticancer, antiviral, neuroprotective, cardioprotective). Moreover, several reports suggest that the variable activity of proTα might be exerted through different parts of the molecule. We first reported that the main immunoactive region of proTα is the carboxy-terminal decapeptide proTα(100-109). In conjunction with data from others, we also revealed that proTα and proTα(100-109) signal through Toll-like receptor 4. Although their precise molecular mechanism of action is yet not fully elucidated, proTα and proTα(100-109) are viewed as candidate adjuvants for cancer immunotherapy. Here, we present a historical overview on the discovery and isolation of thymosins with emphasis on proTα and data on some immune-related new activities of the polypeptide and smaller immunostimulatory peptides thereof. Finally, we propose a compiled scenario on proTα's mode of action, which could eventually contribute to its clinical application.

Prothymosin alpha expression and localization during the spermatogenesis ofDanio rerio

Prothymosin α (PTMA) is a highly acidic, intrinsically disordered protein, which is widely expressed and conserved throughout evolution; its uncommon features are reflected by its involvement in a variety of processes, including chromatin remodelling, transcriptional regulation, cell proliferation and death, immunity. PTMA has also been implicated in spermatogenesis: during vertebrate germ cell progression in the testis the protein is expressed in meiotic and post-meiotic stages, and it is associated with the acrosome system of the differentiating spermatids in mammals. Then, it finally localizes on the inner acrosomal membrane of the mature spermatozoa, suggesting its possible role in both the maturation and function of the gametes. In the present work we studied PTMA expression during the spermatogenesis of the adult zebrafish, a species in which two paralogs have been described. Our data show thatptmatranscripts are expressed in the testis, and localize in meiotic and post-meiotic germ cells, namely spermatocytes and spermatids. Consistently, the protein is expressed in spermatocytes, spermatids, and spermatozoa: its initial perinuclear distribution is extended to the chromatin region during cell division and, in haploid phases, to the cytoplasm of the developing and final gametes. The nuclear localization in the acrosome-lacking spermatozoa suggests a role for PTMA in chromatin remodelling during gamete differentiation. These data further provide a compelling starting point for the study of PTMA functions during vertebrate fertilization.

Expression of prothymosin alpha predicts early recurrence and poor prognosis of hepatocellular carcinoma

BACKGROUND

Prothymosin alpha (PTMA) is a nuclear oncoprotein-transcription factor essential for cell cycle progression and proliferation. PTMA was overexpressed in several human malignancies including hepatocellular carcinoma (HCC). However, the prognostic significance of PTMA protein expression in HCC remains unclear. In the present study, we evaluated PTMA protein expression by immunohistochemistry in order to elucidate the prognostic roles of PTMA in HCC patients.

METHODS

By immunohistochemistry, we investigated the expression of PTMA protein in tumor tissue from 226 HCC patients who underwent curative hepatectomy. Univariate and multivariate analyses were performed to evaluate its predictive value for tumor recurrence and survival of patients. The median follow-up period was 120 months.

RESULTS

PTMA expression was observed in 162 (71.7%) of the 226 HCC patients and was significantly associated with higher Edmondson grade, microvascular invasion, intrahepatic metastasis, higher American Joint Committee on Cancer (AJCC) T-stage, and lower albumin level. PTMA expression was an independent predictor of early recurrence (P=0.001). PTMA expression showed an unfavorable influence on recurrence-free survival (RFS) (P<0.001). Subgroup analysis showed that among patients with tumor size ≤5.0 cm (140 patients), patients at AJCC T-stage 1 (95 patients) and patients with alpha-fetoprotein ≤20 ng/mL (83 patients), the differences in RFS between PTMA-positive and PTMA-negative groups were also statistically significant (P=0.017, P=0.002 and P=0.002, respectively). In addition, PTMA expression was an independent predictor of shorter RFS (P=0.011). PTMA expression showed an unfavorable influence on overall survival (P=0.014), but was not an independent predictor of shorter overall survival (P=0.161).

CONCLUSIONS

PTMA protein expression might be a novel predictor of early recurrence and RFS in HCC patients, even those at early stage or with alpha-fetoprotein-negative after curative hepatectomy. PTMA could be used as an immunohistochemical biomarker to detect patients with a high risk of recurrence.

Oncogenic c-Myc and prothymosin-alpha protect hepatocellular carcinoma cells against sorafenib-induced apoptosis

Prothymosin alpha (PTMA) is overexpressed in various human tumors, including hepatocellular carcinoma (HCC). The significance of PTMA overexpression and its underlying mechanism remain unclear. We show here that silencing PTMA sensitizes HCC cells to the kinase inhibitor sorafenib. In contrast, ectopic expression of PTMA induces cell resistance to the drug. While inhibitors targeting JNK, ERK or PI3K reduce PTMA expression, only ERK activation is suppressed by sorafenib. In addition, inhibition of ERK produces a dramatic decrease in both endogenous PTMA level and promoter activation. Ectopic expression of active MKK1/2 considerably induces PTMA expression. We also identify a sorafenib-responsive segment lying 1000-1500-bp upstream of the PTMA transcription start site and observe that it is controlled by c-Myc and ERK. Mutation in the PTMA promoter at the predicted c-Myc binding site and silencing of c-Myc both abrogate sorafenib's effect on PTMA transcription. We also find that silencing PTMA potentiates Bax translocation to mitochondria in response to sorafenib and this is associated with increased cytochrome c release from mitochondria and enhanced caspase-9 activation. These results indicate that PTMA is positively regulated by the oncoprotein c-Myc and protects HCC cells against sorafenib-induced cell death, thus identifying PTMA as a new target for chemotherapy against HCC.

Prothymosin alpha: a ubiquitous polypeptide with potential use in cancer diagnosis and therapy

The thymus is a central lymphoid organ with crucial role in generating T cells and maintaining homeostasis of the immune system. More than 30 peptides, initially referred to as "thymic hormones," are produced by this gland. Although the majority of them have not been proven to be thymus-specific, thymic peptides comprise an effective group of regulators, mediating important immune functions. Thymosin fraction five (TFV) was the first thymic extract shown to stimulate lymphocyte proliferation and differentiation. Subsequent fractionation of TFV led to the isolation and characterization of a series of immunoactive peptides/polypeptides, members of the thymosin family. Extensive research on prothymosin α (proTα) and thymosin α1 (Tα1) showed that they are of clinical significance and potential medical use. They may serve as molecular markers for cancer prognosis and/or as therapeutic agents for treating immunodeficiencies, autoimmune diseases and malignancies. Although the molecular mechanisms underlying their effect are yet not fully elucidated, proTα and Tα1 could be considered as candidates for cancer immunotherapy. In this review, we will focus in principle on the eventual clinical utility of proTα, both as a tumor biomarker and in triggering anticancer immune responses. Considering the experience acquired via the use of Tα1 to treat cancer patients, we will also discuss potential approaches for the future introduction of proTα into the clinical setting.

Preliminary methylation analysis of prothymosin α genomic sequences

Prothymosin α is a mammalian nuclear protein involved in cell proliferation and differentiation. Here, we carried out the first study of the methylation status of ProTα genomic sequences in cell lines during differentiation as well as in tumoral tissues. We found that there is hypermethylation in all cell lines analyzed with a pattern that is characteristic of each cell type revealing specific genomic reorganizations. The decrease of ProTα mRNA during differentiation was not accompanied by changes in the methylation status. Remarkably, we found that there is hypomethylation in gastrointestinal tumors when compared with the peritumoral tissue. The biological implications of these findings are discussed.

Intracellular and extracellular cytokine-like functions of prothymosin α: implications for the development of immunotherapies

Prothymosin α (ProTα) is a 12.5-kDa, highly acidic protein widely distributed in different cell types expressed intracellularly and extracellularly. ProTα does not contain a secretion-signal sequence and is released by a nonclassical secretory pathway with a cargo protein. New findings on the extracellular function of ProTα have yielded exciting insights into the cytokine-like functions of this host protein that stimulates type I interferon via Toll-like receptor 4. Here, we discuss the intracellular function of ProTα, how new findings of cytokine-like activities of ProTα aid our understanding of mechanisms that direct ProTα functions, and the potential application of these new insights to the development of immunotherapies.

Overexpression of prothymosin alpha predicts poor disease outcome in head and neck cancer

Background

In our recent study, tissue proteomic analysis of oral pre-malignant lesions (OPLs) and normal oral mucosa led to the identification of a panel of biomarkers, including prothymosin alpha (PTMA), to distinguish OPLs from histologically normal oral tissues. This study aimed to determine the clinical significance of PTMA overexpression in oral squamous cell hyperplasia, dysplasia and head and neck squamous cell carcinoma (HNSCC).

Methodology

Immunohistochemistry of PTMA protein was performed in HNSCCs (n = 100), squamous cell hyperplasia (n = 116), dysplasia (n = 50) and histologically normal oral tissues (n = 100). Statistical analysis was carried out to determine the association of PTMA overexpression with clinicopathological parameters and disease prognosis over 7 years for HNSCC patients.

Results

Our immunohistochemical analysis demonstrated significant overexpression of nuclear PTMA in squamous cell hyperplasia (63.8%), dysplasia (50%) and HNSCC (61%) in comparison with oral normal mucosa (p_trend<0.001). Chi-square analysis showed significant association of nuclear PTMA with advanced tumor stages (III+IV). Kaplan Meier survival analysis indicated reduced disease free survival (DFS) in HNSCC patients (p<0.001; median survival 11 months). Notably, Cox-multivariate analysis revealed nuclear PTMA as an independent predictor of poor prognosis of HNSCC patients (p<0.001, Hazard's ratio, HR = 5.2, 95% CI = 2.3–11.8) in comparison with the histological grade, T-stage, nodal status and tumor stage.

Conclusions

Nuclear PTMA may serve as prognostic marker in HNSCC to determine the subset of patients that are likely to show recurrence of the disease.

Novel small molecules relieve prothymosin alpha-mediated inhibition of apoptosome formation by blocking its interaction with Apaf-1

Structurally diverse small molecules, including 5-(2-benzofuryl)-4-phenyl-1,2,4-triazole-3-thiol (BETT), have been identified via high-throughput screening as activators of caspase-3 in HeLa cell extracts. However, little is known about their mechanism of action. In this study, we investigate how BETT regulates prothymosin alpha (ProT), a nuclear protein previously shown to play essential roles in apoptosis. We first showed that Apaf-1 is the direct target protein of BETT. We further demonstrated that BETT relieved ProT-mediated inhibition of apoptosome formation by blocking the interaction between Apaf-1 and ProT. Using two-dimensional (1)H-(15)N heteronuclear single-quantum correlation (HSQC) experiments, we were also able to examine the interaction between Apaf-1 and (15)N-labeled ProT alpha. Furthermore, we were able to reconstitute the entire caspase-3 activation pathway using purified ProT, Apaf-1, procaspase-9, procaspase-3, Hsp70, cytochrome c, PHAPI, CAS, and regulatory compounds to mimic stress-induced apoptosis in vitro. Together, these studies would lead to novel and specific methods for the prevention, diagnosis, and treatment of human cancer.

Transgenic expression of prothymosin alpha on zebrafish epidermal cells promotes proliferation and attenuates UVB-induced apoptosis

This study generated a transgenic zebrafish line Tg(k18:Ptmaa-RFP) with overexpression of Prothymosin alpha type a (Ptmaa) in the skin epidermis. Red fluorescence first appears very weakly in the early stage, become stronger and mainly restricted in the nuclei of the epithelial cells from 3 dpf-larvae to adult fish. However, no evident morphological abnormalities were observed. Thus, overexpression of Ptmaa alone is not sufficient to cause disorganized growths or even cancer in zebrafish skin. Molecular and histological evidences showed that Tg(k18:Ptmaa-RFP) embryos have more proliferating cells in the pelvic fins [WT: 3.92 +/- 7.15; Tg(k18:Ptmaa-RFP): 38.00 +/- 10.87] and thicker skin [WT: 10.98 +/- 1.41 mum; Tg(k18:Ptmaa-RFP): 14.02 +/- 1.32 mum], indicating that overexpression of Ptmaa can promote proliferation. On the other hand, fewer apoptotic signals were found when Tg(k18:Ptmaa-RFP) embryos were exposed to UVB. Together with quantitative RT-PCR data, we suggest that UVB-induced epidermal cell apoptosis of zebrafish larvae can be attenuated by overexpression of Ptmaa through the enhancement of transcriptions of bcl2 mRNAs. Taken together, we conclude that overexpression of Ptmaa in zebrafish epidermal cells promotes proliferation and attenuates UVB-induced apoptosis but does not cause skin cancer.

Differential protein expressions in renal cell carcinoma: new biomarker discovery by mass spectrometry

Renal cell carcinoma (RCC) is the most common neoplasm in the adult kidney. Unfortunately, there are currently no biomarkers for the diagnosis of RCC. In addition to early detection, biomarkers have a potential use for prognosis, for monitoring recurrence after treatment, and as predictive markers for treatment efficiency. In this study, we identified proteins that are dysregulated in RCC, utilizing a quantitative mass spectrometry analysis. We compared the protein expression of kidney cancer tissues to their normal counterparts from the same patient using LC-MS/MS. iTRAQ labeling permitted simultaneous quantitative analysis of four samples (cancer, normal, and two controls) by separately tagging the peptides in these samples with four cleavable mass-tags (114, 115, 116, and 117 Da). The samples were then pooled, and the tagged peptides resolved first by strong cation exchange chromatography and then by nanobore reverse phase chromatography coupled online to nanoelectrospray MS/MS. We identified a total of 937 proteins in two runs. There was a statistically significant positive correlation of the proteins identified in both runs (r(p) = 0.695, p < 0.001). Using a cutoff value of 0.67 fold for underexpression and 1.5 fold for overexpression, we identified 168 underexpressed proteins and 156 proteins that were overexpressed in RCC compared to normal tissues. These dysregulated proteins in RCC were statistically significantly different from those of transitional cell carcinoma and end-stage glomerulonephritis. We performed an in silico validation of our results using different tools and databases including Serial Analysis of Gene Expression (SAGE), UniGene EST ProfileViewer, Cancer Genome Anatomy Project, and Gene Ontology consortium analysis.

Aberrant prothymosin-alpha expression in human bladder cancer

OBJECTIVES

To investigate the prothymosin-alpha (PTMA) expression in human bladder cancer using tissue microarrays.

METHODS

Two tissue microarray slides of 50 bladder tumors and 42 paired normal adjacent tissues were investigated using immunohistochemical staining. The staining distribution was categorized as negative, nuclear, cytoplasmic, and mixed expression. Quantitative immunoreactivity was measured using image analysis, as represented by the integrated optical density for each tissue core.

RESULTS

In 36 of 42 normal adjacent tissues, positive PTMA immunoreactivity could be seen in some nuclei of the normal urothelial cells, but not, or only minimally, in the cytoplasm and underlying submucosal tissues. A statistically significant enhancement of PTMA expression was found in bladder tumors of each grade compared with the normal adjacent tissue (P < .0001 for normal adjacent tissues vs grade 1, 2, or 3 tumors, paired t test). Of 48 transitional cell carcinoma specimens, only 4 (8.3%) were graded as negative and 44 (91.7%) were positive for PTMA expression, including nuclear (n = 8), cytoplasmic (n = 12), and mixed expression (n = 24) patterns. A statistically significant correlation was found between high grade and mixed expression (P = 0.0020, chi(2) test).

CONCLUSIONS

Increased PTMA expression was found in human bladder cancers compared with the paired normal adjacent bladder tissue. The distribution of PTMA expression was changed in high-grade tumors. The clinical significance of such an aberrant PTMA expression in bladder cancer is worthy of additional investigation.

Discovery and verification of head-and-neck cancer biomarkers by differential protein expression analysis using iTRAQ labeling, multidimensional liquid chromatography, and tandem mass spectrometry

Multidimensional LC-MS/MS has been used for the analysis of biological samples labeled with isobaric mass tags for relative and absolute quantitation (iTRAQ) to identify proteins that are differentially expressed in human head-and-neck squamous cell carcinomas (HNSCCs) in relation to non-cancerous head-and-neck tissues (controls) for cancer biomarker discovery. Fifteen individual samples (cancer and non-cancerous tissues) were compared against a pooled non-cancerous control (prepared by pooling equal amounts of proteins from six non-cancerous tissues) in five sets by on-line and off-line separation. We identified 811 non-redundant proteins in HNSCCs, including structural proteins, signaling components, enzymes, receptors, transcription factors, and chaperones. A panel of proteins showing consistent differential expression in HNSCC relative to the non-cancerous controls was discovered. Some of the proteins include stratifin (14-3-3sigma); YWHAZ (14-3-3zeta); three calcium-binding proteins of the S100 family, S100-A2, S100-A7 (psoriasin), and S100-A11 (calgizarrin); prothymosin alpha (PTHA); L-lactate dehydrogenase A chain; glutathione S-transferase Pi; APC-binding protein EB1; and fascin. Peroxiredoxin2, carbonic anhydrase I, flavin reductase, histone H3, and polybromo-1D (BAF180) were underexpressed in HNSCCs. A panel of the three best performing biomarkers, YWHAZ, stratifin, and S100-A7, achieved a sensitivity of 0.92 and a specificity of 0.91 in discriminating cancerous from non-cancerous head-and-neck tissues. Verification of differential expression of YWHAZ, stratifin, and S100-A7 proteins in clinical samples of HNSCCs and paired and non-paired non-cancerous tissues by immunohistochemistry, immunoblotting, and RT-PCR confirmed their overexpression in head-and-neck cancer. Verification of YWHAZ, stratifin, and S100-A7 in an independent set of HNSCCs achieved a sensitivity of 0.92 and a specificity of 0.87 in discriminating cancerous from non-cancerous head-and-neck tissues, thereby confirming their overexpressions and utility as credible cancer biomarkers.

Effectiveness of gene expression profiling for response prediction of rectal cancer to preoperative radiotherapy

BACKGROUND

Our aim was to determine whether the expression levels of specific genes could predict clinical radiosensitivity in human colorectal cancer.

METHODS

Radioresistant colorectal cancer cell lines were established by repeated X-ray exposure (total, 100 Gy), and the gene expressions of the parent and radioresistant cell lines were compared in a microarray analysis. To verify the microarray data, we carried out a reverse transcriptase-polymerase chain reaction analysis of identified genes in clinical samples from 30 irradiated rectal cancer patients.

RESULTS

A comparison of the intensity data for the parent and three radioresistant cell lines revealed 17 upregulated and 142 downregulated genes in all radioresistant cell lines. Next, we focused on two upregulated genes, PTMA (prothymosin alpha) and EIF5a2 (eukaryotic translation initiation factor 5A), in the radioresistant cell lines. In clinical samples, the expression of PTMA was significantly higher in the minor effect group than in the major effect group (P = 0.004), but there were no significant differences in EIF5a2 expression between the two groups.

CONCLUSIONS

We identified radiation-related genes in colorectal cancer and demonstrated that PTMA may play an important role in radiosensitivity. Our findings suggest that PTMA may be a novel marker for predicting the effectiveness of radiotherapy in clinical cases.

Altered expression of estrogen receptor alpha and beta in advanced gastric adenocarcinoma: correlation with prothymosin alpha and clinicopathological parameters

AIMS

We aimed to investigate the sources of estrogen receptor alpha (ERalpha), estrogen receptor beta (ERbeta) and estimate the value of both ER subtypes in gastric adenocarcinoma and analyze the possible relationship of prothymosin alpha (ProTalpha) to ERs.

METHODS

ERs at the mRNA and protein levels in matched advanced gastric adenocarcinomas and surrounding non-cancerous tissues were examined by using reverse transcription-polymerase chain reaction and immunohistochemical (IHC) methods. Cell proliferation related protein ProTalpha was also detected in IHC. The immunoreactive signal, corresponding to the proteins expression level, was quantitatively analyzed.

RESULTS

Both ERalpha and ERbeta mRNAs were detected in most of the cancer and matched normal tissues analyzed. At the protein level, the percentage of ERalpha and ERbeta positive cases changed. ERalpha immunoreactivity was only detected in poorly differentiated adenocarcinoma and ERalpha positive expression correlated with depth of invasion of the tumors. Compared with non-cancerous tissues, gastric tumors showed decreased ERbeta expression and lost ERbeta. Altered ERbeta in gastric adenocarcinoma correlated with decreased differentiation. And the tumors involved lymph node metastasis showed significantly lower expression level of ERbeta. ProTalpha in ERbeta-positive tumors showed higher expression than that in lost ERbeta tumors.

CONCLUSIONS

Altered expression of ERalpha and ERbeta in tumors compared with corresponding normal gastric tissues was more common in poorly differentiated adenocarcinomas and related to malignant properties, such as lymph node metastasis. Decreased ERbeta and increased ProTalpha expression in advanced gastric adenocarcinoma indicated that ERbeta may play an anti-proliferation role which is opposed to the role of ProTalpha in gastric epithelium.

Expression and prognostic significance of prothymosin-alpha and ERp57 in human gastric cancer

PURPOSE

Prothymosin-alpha and ERp57 were previously identified as markers for gastric metaplasia in a mouse model of Helicobacter-induced gastric metaplasia and neoplasia. In this paper we assess whether the expression of these putative biomarkers in humans is correlated with gastric metaplasia and adenocarcinoma and clinical outcomes.

METHODS

Eight tissue microarrays, containing 749 paraffin-embedded tissue cores from 164 gastric cancer patients, were stained for prothymosin-alpha and ERp57 by horseradish peroxidase immunohistochemical techniques. The proportion of stained cells per core was quantitated using the Ariol SL-50 automated image analysis system.

RESULTS

Prothymosin-alpha stained a significantly higher percentage of nuclei in cancer and metastases compared with normal gastric mucosa. ERp57 staining was significantly decreased in cancer and metastases compared with both normal gastric mucosa and metaplasias. ERp57 expression also correlated with greater depth of tumor invasion and advanced stage of disease. Kaplan-Meier survival analysis determined that tumors with the highest quartile of ERp57 expression were statistically associated with longer postoperative survival. A Cox proportional hazard analysis showed that maintenance of ERp57 expression was associated with longer postoperative survival.

CONCLUSIONS

These results suggest that although prothymosin-alpha is overexpressed in gastric adenocarcinoma, it is not associated with alterations in survival. In contrast, loss of ERp57 expression correlated with more aggressive disease and could provide useful prognostic information for gastric cancer patients.

Apoptotic and proliferating hepatocytes differ in prothymosin α expression and cell localization

Prothymosin alpha is an acidic protein, reported to be involved in cell proliferation and apoptosis, although its precise function in both processes are still unknown. Due to the importance of these processes in the pathogenesis of hepatic diseases and the need to understand the molecular mechanisms underlying these diseases we aimed to investigate the behavior of this protein in liver growth and apoptosis, in two models of hepatocytes in culture. Prothymosin alpha expression varied throughout the hepatocyte cell cycle, according to its progression. Proliferating hepatocytes showed increased expression of the protein, while apoptotic ones showed decreased levels. The subcellular location of prothymosin alpha differed according to the different phases of the cell cycle. Thus, it appeared with a stippled and widely dispersed pattern throughout the nucleus in quiescent and proliferating hepatocytes, while it became cytoplasmic in mitotic and late apoptotic cells. These results are in agreement with the idea that high levels of prothymosin alpha need to be present in the nucleus for proliferation, and programmed cell death requires low levels of prothymosin alpha outside of the nucleus. The differences in prothymosin alpha expression and localization during hepatocyte proliferation and apoptosis suggest that this protein may have a pleiotropic function that depends not only on its availability but also on its various localizations in different subcellular compartments.

Thymosinalpha1 stimulates cell proliferation by activating ERK1/2, JNK, and increasing cytokine secretion in human pancreatic cancer cells

In this study, we investigated the expression and function of thymosinalpha1 (Thyalpha1) in human pancreatic cancer. We found that human pancreatic cancer cell lines Panc-1, Panc03.27, ASPC-1, and PL45 cells significantly over-expressed the mRNA of Thyalpha1 as compared to the normal human pancreatic ductal epithelium (HPDE) cells.. Thyalpha1 mRNA and protein levels were also over-expressed in clinical pancreatic adenocarcinoma specimens. In addition, synthetic Thyalpha1 significantly promoted Panc-1 cell proliferation and increased phosphorylation of ERK1/2 and JNK. Furthermore, Thyalpha1 increased the secretion of multiple cytokines including IL-10, IL-13, and IL-17 in Panc-1 cells. Thus, Thyalpha1 may have a new role in pancreatic cancer pathogenesis.

Identification of novel genes expressed during rhabdomyosarcoma differentiation using cDNA microarrays

Rhabdomyosarcomas (RMS) are highly aggressive tumors that are thought to arise as a consequence of the regulatory disruption of the growth and differentiation of skeletal muscle progenitor cells. Normal myogenesis is characterized by the expression of the myogenic regulatory factor gene family but, despite their expression in RMS, these tumor cells fail to complete the latter stages of myogenesis. The RMS cell line RD-A was treated with 12-O-tetradecanoylphorbol-13-acetate to induce differentiation and cultured for 10 days. RNA was extracted on days 1, 3, 6, 8 and 10. A human skeletal muscle cDNA microarray was developed and used to analyze the global gene expression of RMS tumors over the time-course of differentiation. As a comparison, the genes identified were subsequently examined during the differentiated primary human skeletal muscle cultures. Prothymosin alpha (PTMA), and translocase of inner mitochondrial membrane 10 (Tim10), two genes not previously implicated in RMS, showed reduced expression during differentiation. Marked differences in the expression of PTMA and Tim10 were observed during the differentiation of human primary skeletal muscle cells. These results identify several new genes with potential roles in the myogenic arrest present in rhabdomyosarcoma. PTMA expression in RMS biopsy samples might prove to be an effective diagnostic marker for this disease.

Expression of prothymosin alpha is correlated with development and progression in human prostate cancers

BACKGROUND

Our previous study clearly demonstrated that decreased expression of prothymosin alpha (PTMA) was associated with inhibition of rat prostate carcinogenesis by isoflavones. The purpose of the present investigation was to provide a better understanding of the role of PTMA in human prostate cancers.

METHODS AND RESULTS

PTMA expression in 68 prostate cancer cases and in prostate cancer cell lines was examined by immunohistochemistry and immunoblotting, and its levels were increased with progression from normal epithelium, through prostatic intraepithelial neoplasia (PIN) to carcinomas, correlating with the Gleason's pattern. All cell lines studied (LNCaP, 22Rv1, DU145, and PC3) showed high PTMA expression compared with prostate epithelial cells (PrEC). Knockdown of PTMA expression in PC3 cells by RNAi resulted in the inhibition of both cell growth and invasion in vitro.

CONCLUSIONS

The present study clearly demonstrated that PTMA expression is intimately involved in the differentiation and progression of human prostate cancers, and could be a target for therapy and diagnostic purposes.

Transcription factor-mediated proliferation and apoptosis in benign and malignant thyroid lesions

Transcription factors play an essential role in regulating both cell proliferation and programmed cell death. Proliferation and apoptosis-related transcription factor immunoexpression patterns were concomitantly investigated in tissue sections of normal thyroid, goiters, follicular adenomas and well-differentiated papillary and follicular carcinomas using antibodies against prothymosin alpha, E2F-1, p53, Bcl2, and Bax proteins. Proliferation and apoptotic indices were determined by Ki-67 immunoreactivity and the terminal deoxynucleotidyl transferase-mediated deoxy uridine triphosphate nick-end labeling technique, respectively. Prothymosin alpha and E2F-1 immunoexpression levels were found to be significantly elevated in well-differentiated carcinomas compared to adenomas, goiters and normal tissues (P < 0.05). Both proteins were directly correlated with the proliferation index (P < 0.05). E2F-1 was additionally correlated with the apoptotic index (P < 0.05). The majority of cases were negative for p53 staining. Positive Bcl2 immunostaining was detected in all thyroid histotypes. None of the normal tissues showed Bax immunoreactivity, while positive accumulation differed significantly between hyperplastic and neoplastic histotypes. Direct correlations were observed between prothymosin alpha and Bcl2 as well as between E2F-1 and Bax immunoexpression (P < 0.05). These data demonstrate that prothymosin alpha and E2F-1 are strongly involved in the proliferation processes of thyroid neoplasias. Furthermore, prothymosin alpha may promote cell survival through the Bcl2 anti-apoptotic pathway, while E2F-1-induced apoptosis via p53-independent pathways may be associated with transcriptional activation of bax pro-apoptotic gene.

Roles of thymosins in cancers and other organ systems

Thymosins are small peptides, originally identified from the thymus, but now known to be more widely distributed in many tissues and cells. Thymosins are divided into three main groups, alpha-, beta-, : and gamma-thymosins, based on their isoelectric points. alpha-thymosins (ProTalpha, Talphal) have nuclear localization and are involved in transcription and/or DNA replications; whereas beta-thymosins (Tbeta4, Tbeta10, Tbetal5) have cytoplasmic localization and show high affinity to G-actin for cell mobility. Furthermore, it is well known that both alpha- and beta-thymosins play important roles in modulating immune response, vascular biology, and cancer pathogenesis. More importantly, thymosins may have significant clinical applications. They may serve as molecular markers for the diagnosis and prognosis of certain diseases. In addition, they could be molecular targets of certain diseases or be used as therapeutic agents to treat certain diseases. However, the molecular mechanisms of action of thymosins are largely unknown. This review not only presents recent advances of basic science research of thymosins and their clinical applications but provides thoughtful views for future directions of investigation on thymosins.

Screening tests for hepatocellular carcinoma

The incidence of hepatocellular carcinoma (HCC) is rising throughout the world. HCC meets the criteria for which a disease benefits from screening or surveillance: it is an important health problem; those with cirrhosis are the targets for surveillance; there is acceptable treatment if diagnosed early; surveillance using alpha-fetoprotein and ultrasound has been shown to be cost effective; surveillance is widely implemented by health care professionals and accepted by patients; standardized recall procedures exists; and the screening tests must achieve an acceptable level of accuracy in the population undergoing screening. The latter point is the main limitation of surveillance for HCC. In this review we will discuss the currently available tests for the surveillance of HCC.

Antiapoptotic function of RNA-binding protein HuR effected through prothymosin alpha

We report the antiapoptotic effect of RNA-binding protein HuR, a critical regulator of the post-transcriptional fate of target transcripts. Among the most prominent mRNAs complexing with HuR is that encoding prothymosin alpha (ProTalpha), an inhibitor of the apoptosome. In HeLa cells, treatment with the apoptotic stimulus ultraviolet light (UVC) triggered the mobilization of ProTalpha mRNA to the cytoplasm and onto heavier polysomes, where its association with HuR increased dramatically. Analysis of a chimeric ProTalpha mRNA directly implicated HuR in regulating ProTalpha production: ProTalpha translation and cytoplasmic concentration increased in HuR-overexpressing cells and declined in cells in which HuR levels were lowered by RNA interference. Importantly, the antiapoptotic influence engendered by HuR was vitally dependent on ProTalpha expression, since use of oligomers that blocked ProTalpha translation abrogated the protective effect of HuR. Together, our data support a regulatory scheme whereby HuR binds the ProTalpha mRNA, elevates its cytoplasmic abundance and translation, and thereby elicits an antiapoptotic program.

Cytochrome C-mediated apoptosis

Apoptosis, or programmed cell death, is involved in development, elimination of damaged cells, and maintenance of cell homeostasis. Deregulation of apoptosis may cause diseases, such as cancers, immune diseases, and neurodegenerative disorders. Apoptosis is executed by a subfamily of cysteine proteases known as caspases. In mammalian cells, a major caspase activation pathway is the cytochrome c-initiated pathway. In this pathway, a variety of apoptotic stimuli cause cytochrome c release from mitochondria, which in turn induces a series of biochemical reactions that result in caspase activation and subsequent cell death. In this review, we focus on the recent progress in understanding the biochemical mechanisms and regulation of the pathway, the roles of the pathway in physiology and disease, and their potential therapeutic values.

Spasmolytic polypeptide expressing metaplasia to preneoplasia in H. felis-infected mice

BACKGROUND & AIMS

The emergence of oxyntic atrophy and metaplastic cell lineages in response to chronic Helicobacter pylori infection predisposes to gastric neoplasia. We have described a trefoil factor family 2 (TFF2; spasmolytic polypeptide) expressing metaplasia (SPEM) associated with gastric neoplasia in both rodent and human fundus. To examine the relationship of SPEM to the neoplastic process in the H. felis -infected C57BL/6 mouse, we have now studied the association of SPEM-related transcripts with preneoplasia.

METHODS

SPEM-related transcripts were identified by microarray analysis of amplified cRNA from SPEM, and surface mucous cells were isolated by laser capture microdissection from the same gastric sections from male C57BL/6 mice infected with H. felis for 6 months. Expression of SPEM-related transcripts was assessed by in situ hybridization and quantitative RT-PCR, as well as immunohistochemistry for prothymosin alpha.

RESULTS

Eleven SPEM-related transcripts were identified as detectable only in SPEM. The expression of the SPEM-related transcripts was validated by in situ hybridization and quantitative PCR. One transcript, the noncoding RNA Xist, was only identified in SPEM cells from the infected male mice. Ten of the 11 transcripts as well as TFF2 were also expressed in regions of gastritis cystica profunda. Immunocytochemistry for one of the identified proteins, prothymosin alpha, demonstrated prominent nuclear staining in SPEM and gastritis cystica profunda.

CONCLUSIONS

The expression of SPEM-related transcripts in regions of gastritis cystica profunda suggests that SPEM represents a precursor lineage for the development of dysplasia in this animal model of gastric carcinogenesis.

Gene expression profile linked to p53 status in hepatitis C virus-related hepatocellular carcinoma

To clarify the role of p53 in 22 hepatitis C virus (HCV)-infected hepatocellular carcinomas (HCCs), we compared the gene expression profiles of HCCs with wild-type p53 (wt-p53) (n=17) and those with mutant-type p53 (mt-p53) (n=5) by oligonucleotide microarray analysis. Among 83 p53-related genes identified by a supervised learning method, 25 were underexpressed, and 58 were overexpressed in mt-p53 HCCs compared with wt-p53 HCCs. With a computer search, we identified consensus p53-binding sequences in the 3-kb region upstream of the translation initiation site in 59 of the 83 genes, suggesting that the in vivo p53-associated transcription system is very complicated. These data will provide additional insights into p53-related pathogenesis in HCV-infected HCC.

Suppressive effect of overexpressed connective tissue growth factor on tumor cell growth in a human oral squamous cell carcinoma-derived cell line

Connective tissue growth factor (CTGF) is known to be a multifunctional growth factor that is overexpressed in several types of malignancies. In this study, effects of CTGF gene overexpression on the phenotypes of oral squamous cell carcinoma cells were investigated by using a cell line with undetectable endogenous CTGF expression. Surprisingly, our results indicated that CTGF-overexpressed clones were characterized by attenuated cell growth and less potent tumorigenicity, with coincidental downregulation of prothymosin alpha gene. Although CTGF is known to promote cell proliferation in mesenchymal cells, our present results suggest that CTGF acts as a negative regulator of the cell growth in oral squamous cell carcinoma possibly through its interaction with growth modifiers inside the cell.

Distinctive roles of PHAP proteins and prothymosin-alpha in a death regulatory pathway

A small molecule, alpha-(trichloromethyl)-4-pyridineethanol (PETCM), was identified by high-throughput screening as an activator of caspase-3 in extracts of a panel of cancer cells. PETCM was used in combination with biochemical fractionation to identify a pathway that regulates mitochondria-initiated caspase activation. This pathway consists of tumor suppressor putative HLA-DR-associated proteins (PHAP) and oncoprotein prothymosin-alpha (ProT). PHAP proteins promoted caspase-9 activation after apoptosome formation, whereas ProT negatively regulated caspase-9 activation by inhibiting apoptosome formation. PETCM relieved ProT inhibition and allowed apoptosome formation at a physiological concentration of deoxyadenosine triphosphate. Elimination of ProT expression by RNA interference sensitized cells to ultraviolet irradiation-induced apoptosis and negated the requirement of PETCM for caspase activation. Thus, this chemical-biological combinatory approach has revealed the regulatory roles of oncoprotein ProT and tumor suppressor PHAP in apoptosis.

Gene expression profile of HIV-1 Tat expressing cells: a close interplay between proliferative and differentiation signals

BACKGROUND

Expression profiling holds great promise for rapid host genome functional analysis. It is plausible that host expression profiling in an infection could serve as a universal phenotype in virally infected cells. Here, we describe the effect of one of the most critical viral activators, Tat, in HIV-1 infected and Tat expressing cells. We utilized microarray analysis from uninfected, latently HIV-1 infected cells, as well as cells that express Tat, to decipher some of the cellular changes associated with this viral activator.

RESULTS

Utilizing uninfected, HIV-1 latently infected cells, and Tat expressing cells, we observed that most of the cellular host genes in Tat expressing cells were down-regulated. The down-regulation in Tat expressing cells is most apparent on cellular receptors that have intrinsic receptor tyrosine kinase (RTK) activity and signal transduction members that mediate RTK function, including Ras-Raf-MEK pathway. Co-activators of transcription, such as p300/CBP and SRC-1, which mediate gene expression related to hormone receptor genes, were also found to be down-regulated. Down-regulation of receptors may allow latent HIV-1 infected cells to either hide from the immune system or avoid extracellular differentiation signals. Some of the genes that were up-regulated included co-receptors for HIV-1 entry, translation machinery, and cell cycle regulatory proteins.

CONCLUSIONS

We have demonstrated, through a microarray approach, that HIV-1 Tat is able to regulate many cellular genes that are involved in cell signaling, translation and ultimately control the host proliferative and differentiation signals.

Expression of the prothymosin alpha mRNA correlated with that of N-myc in neuroblastoma

Neuroblastoma is the most common malignant solid cancers in early childhood. Overexpression of the proto-oncogene, N-myc, has been reported to be correlated with more malignant course of the disease. Prothymosin alpha, a cellular proliferation-associated gene, is reported to be a target of myc and elevated in several malignant cells and tissues. Expression of prothymosin alpha and N-myc messenger RNAs were evaluated by real-time reverse transcription polymerase chain reaction (RT-PCR) assay in 18 tumor samples from neuroblastoma using LightCycler. The data was analyzed in reference to clinicopathological factors. There was a tendency that higher prothymosin alpha transcripts levels in the tumor samples from younger patients (<1year.) when compared to the older group (>1 year.) (P=0.0845). There was no relationship between prothymosin alpha gene expression and gender (P=0.3029), mass screening case or not (P=0.3007), or stage. The prothymosin alpha mRNA expression levels were correlated with N-myc mRNA levels (P=0.006). Thus we suggest that prothymosin alpha plays an active role as a target of N-myc in neuroblastoma.

Thymic hormones in cancer diagnostics and treatment

The thymus is an endocrine organ. A unified, physiological concept of humoral regulation of the immune response emerged in the last three decades. The thymus is the primary major site of production of immunocompetent T-lymphocytes from their haematopoietic stem cells. The thymus provides a superior humoral microenvironment for the development of immunocompetent T-lymphocytes. Although yolk sac derived pre-T stem cells enter the thymus using a homing receptor, the immigration process requires also secretion of a peptide, called thymotaxin by the cells of the reticulo-epithelial (RE) network. This complex process requires direct cell to cell, receptor based interactions, as well as in situ paracrine information via the numerous cytokines and thymic hormones produced by the RE cells of thymic microenvironment. Thymic hormones induce in situ T-lymphocyte marker differentiation, expression and functions. These polypeptide hormones have also been shown by means of immunocytochemistry to localise in the RE cells of the thymic cellular microenvironment. Based on the complexity of the intrathymic maturation sequence of T-lymphocytes and the increasing numbers of T-lymphocyte subpopulations that are being identified, it would be surprising if a single thymic humoral factor could control all of the molecular steps and cell populations involved. Rather, it would appear that the control of intrathymic T-lymphocyte maturation and functional maturation involves a complex number of thymic-specific factors and other molecules that rigidly control the intermediary steps in the differentiation process. Thymosin fraction 5 (TF5) and its component polypeptides influence a variety of lymphocyte properties including cyclic nucleotide levels, migration inhibitory factor production, T-dependent antibody production and expression of certain surface maturation/differentiation markers. Recently, thymic hormones, mostly thymosins have been employed not only in neoplasms' early detection but also in clinical trials to strengthen the effects of immunomodulators in immunodeficiencies, autoimmune diseases and neoplastic malignancies. Combined chemoimmunotherapeutical antineoplastic treatment seems to be useful. Generally, haematopoietic toxicity of every chemotherapeutical clinical trial can be reduced significantly by the immunotherapy, compared to 50% in patients treated with chemotherapy alone.

Fifteen years of prothymosin alpha: contradictory past and new horizons

Prothymosin alpha (ProTalpha) is a highly acidic and small protein of only 111 amino acids with an unusual primary structure. One would expected it to play an essential role in the organism, as it has a wide distribution and is high conserved among mammals, yet its exact function remains elusive. Despite the number of effects described for ProTalpha, intracellular and extracellular, none are accepted as its physiological role. Furthermore, many other aspects of its biology still remain obscure. In this review, we discuss the structural properties, location, gene family, functions and immunomodulatory activities of and cellular receptors for ProTalpha. These topics are addressed in an attempt to reconcile opposing outlooks while emphasizing those points where scant investigations do exist. We have also re-evaluated some previous results in light of the structural properties of ProTalpha and have found that molecular mimetism could be the underlying basis. This molecular mimicry hypothesis provides a clue that must not be overlooked for a realistic appraisal of future results.

Review of thymic hormones in cancer diagnosis and treatment

The thymus is an endocrine organ. A unified, physiological concept of humoral regulations of the immune response has emerged in the last three decades. The thymus is the major site of production of immunocompetent T lymphocytes from their hematopoietic stem cells. This complex process required direct cell to cell, receptor based interactions, as well as in situ paracrine information via the numerous cytokines and thymic hormones produced by the cells of thymic microenvironment. Thymic hormones induce in situ T-cell marker differentiation, expression and functions. These polypeptide hormones have also been shown by means of immunocytochemistry to localize in the reticulo-epithelial (RE) cells of the thymic cellular microenvironment. Due to the great complexity of the intrathymic maturation sequence of T lymphocytes and the diverse immunophenotypically unique subpopulations of T lymphocytes, it is quite unlikely that a single thymic humoral factor could control all of the molecular steps and cell populations involved. It is much more likely that an extremely rich and diverse, but genetically determined, milieu is present within the thymus, and that thus the control of intrathymic T lymphocyte maturation and the functional maturation of T cells involves the orchestral interaction of various thymic-specific factors and other molecules during the differentiation process. Thymosin fraction 5 and its constituent peptides influence several properties of lymphocytes including cyclic nucleotide levels, migration inhibitory factor production, T-dependent antibody production, as well as the expression of various cell surface maturation/differentiation markers. Recently, derivatives of thymic hormones, mostly of thymosins, have been detected as products of neoplastically transformed cells and employed in the early diagnosis of neoplasms. In clinical trials, thymic hormones strengthen the effects of immunomodulators in immunodeficiencies, autoimmune diseases, and neoplastic malignancies. Combined chemo-immunotherapeutical anti-cancer treatment seems to be more efficacious than chemotherapy alone, and the significant hematopoietic toxicity associated with most chemotherapeutical clinical trials can be reduced significantly by the addition of immunotherapy.