Aberrant expression and distribution of the OCT-4 transcription factor in seminomas

Mechanisms of cisplatin sensitivity and resistance in testicular germ cell tumors and potential therapeutic agents (Review)

Testicular germ cell tumors (TGCTs) are the most common tumors in men aged 20-40 years and are primarily treated with cisplatin-based drugs. Although TGCTs are highly sensitive to DNA damage induced by cisplatin and show a hypersensitive apoptotic response, cisplatin resistance still exists. Emerging evidence shows that cisplatin resistance in TGCTs is mainly related to the inhibition of apoptotic pathways such as MDM2/p53, OCT4/NOXA, PDGFR/PI3K/AKT, inhibition of cell cycle checkpoints, increased methylation or neddylation and DNA repair balance. In this review, recent advances regarding the mechanisms of TGCTs' sensitivity and resistance to cisplatin were summarized and potential therapeutic agents for cisplatin-resistant TGCTs were presented, providing a new therapeutic strategy for drug-resistant TGCTs.

Hutchinson-Gilford progeria patient-derived cardiomyocyte model of carrying LMNA gene variant c.1824 C > T

Cardiovascular diseases, atherosclerosis, and strokes are the most common causes of death in patients with Hutchinson-Gilford progeria syndrome (HGPS). The LMNA variant c.1824C > T accounts for ~ 90% of HGPS cases. The detailed molecular mechanisms of Lamin A in the heart remain elusive due to the lack of appropriate in vitro models. We hypothesize that HGPS patient's induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iCMCs) will provide a model platform to study the cardio-pathologic mechanisms associated with HGPS. To elucidate the effects of progerin in cardiomyocytes, we first obtained skin fibroblasts (SFs) from a de-identified HGPS patient (hPGP1, proband) and both parents from the Progeria Research Foundation. Through Sanger sequencing and restriction fragment length polymorphism, with the enzyme EciI, targeting Lamin A, we characterized hPGP1-SFs as heterozygous mutants for the LMNA variant c.1824 C > T. Additionally, we performed LMNA exon 11 bisulfite sequencing to analyze the methylation status of the progeria cells. Furthermore, we reprogrammed the three SFs into iPSCs and differentiated them into iCMCs, which gained a beating on day 7. Through particle image velocimetry analysis, we found that hPGP1-iCMCs had an irregular contractile function and decreased cardiac-specific gene and protein expressions by qRT-PCR and Western blot. Our progeria-patient-derived iCMCs were found to be functionally and structurally defective when compared to normal iCMCs. This in vitro model will help in elucidating the role of Lamin A in cardiac diseases and the cardio-pathologic mechanisms associated with progeria. It provides a new platform for researchers to study novel treatment approaches for progeria-associated cardiac diseases.

RNA-Binding Proteins Play an Important Role in the Prognosis of Patients With Testicular Germ Cell Tumor

Testicular germ cell tumors (TGCTs) are common urological neoplasms in young adult males. The outcome of TGCT depends on pathologic type and tumor stage. RNA-binding proteins (RBPs) influence numerous cancers via post-transcriptional regulation. The prognostic importance of RBPs in TGCT has not been fully investigated. In this study, we set up a prognostic risk model of TGCT using six significantly differentially expressed RBPs, namely, TRMT61A, POLR2J, DIS3L2, IFIH1, IGHMBP2, and NPM2. The expression profiles were downloaded from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression datasets. We observed by performing least absolute shrinkage and selection operator (LASSO) regression analyses that in the training cohort, the expression of six RBPs was correlated with disease-free survival in patients with TGCT. We assessed the specificity and sensitivity of 1-, 3-, 5-, and 10-year survival status prediction using receiver operating characteristic curve analysis and successfully validated using the test cohorts, the entire TCGA cohort, and Gene Expression Omnibus (GEO) datasets. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and gene set enrichment analyses were carried out to seek the possible signaling pathways related with risk score. We also examined the association between the model based on six RBPs and different clinical characteristics. A nomogram was established for TGCT recurrence prediction. Consensus clustering analysis was carried out to identify the clusters of TGCT with different clinical outcomes. Ultimately, external validations of the six-gene risk score were performed by using the GSE3218 and GSE10783 datasets downloaded from the GEO database. In general, our study constructed a prognostic model based on six RBPs, which could serve as independent risk factor in TGCT, especially in seminoma, and might have brilliant clinical application value.

Sensitive detection of transcription factor by coupled fluorescence-encoded microsphere with exonuclease protection

Aberrant transcription factors (TFs) activities are closely related to the occurrence and development of various diseases. Herein, we presented a fluorescence-encoded microsphere-based approach for TFs detection coupling with common DNA footprinting assay. Target TFs specifically bound the binding sites of double-stranded DNA (dsDNA) probes which were conjugated to microspheres. Thus, the probes were protected from being hydrolyzed by exonuclease III (Exo III). Afterwards, biotins labeled on the probes reacted with streptavidin-phycoerythrin (SA-PE) to produce fluorescent signal; however, in the absence of target TFs, the dsDNA probes would be hydrolyzed by Exo III resulting in biotins falling off and thus fluorescence signal was not generated. This strategy can be used to detect nuclear factor-kappa B p50 (NF-κB p50) with a detection limit of 0.2 nM. The steric hindrance of microspheres overcome the disadvantage of Exo III that can nibble into the protein-bound DNA region. Meanwhile, the fluorescent label of microsphere was specific to each TF, enabling multiplex detection could be achieved by changing specific protein binding site of corresponding dsDNA probe. This method has been successfully applied for simultaneous detection of NF-κB p50, AP-1 and CREB in nuclear extract isolated from HeLa cells stimulated or unstimulated by TNF-α, showing great potential for biomedical researches and precise disease diagnosis.

Fermented Ginseng Extract, BST204, Suppresses Tumorigenesis and Migration of Embryonic Carcinoma through Inhibition of Cancer Stem Cell Properties

The pharmacological effects of BST204—a fermented ginseng extract—on several types of cancers have been reported. However, the effects of ginseng products or single ginsenosides against cancer stem cells are still poorly understood. In this study, we identified the anti-tumorigenic and anti-invasive activities of BST204 through the suppression of the cancer stem cell marker, CD133. The treatment of embryonic carcinoma cells with BST204 induced the expression of the tumor suppressor protein, p53, which decreased the expression of cell cycle regulatory proteins and downregulated the expression of CD133 and several stemness transcription factors. These changes resulted in both the inhibition of tumor cell proliferation and tumorigenesis. The knockdown of CD133 suggests that it has a role in tumorigenesis, but not in cancer cell proliferation or cell cycle arrest. Treatment with BST204 resulted in the reduced expression of the mesenchymal marker, N-cadherin, and the increased expression of the epithelial marker, E-cadherin, leading to the suppression of tumor cell migration and invasion. The knockdown of CD133 also exhibited an anti-invasive effect, indicating the role of CD133 in tumor invasion. The single ginsenosides Rg3 and Rh2—major components of BST204—exhibited limited effects against cancer stem cells compared to BST204, suggesting possible synergism among several ginsenoside compounds.

Antibody free ELISA-like assay for the detection of transcription factors based on double-stranded DNA thermostability

Transcription factors (TFs) play critical roles in gene expression regulation and disease development. Herein we report a chemiluminescence assay for the detection of transcription factor based on double-stranded DNA thermostability.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Germ cell differentiation of mouse embryonic stem cells can be influenced by the culture medium

Although embryonic stem (ES) cells can differentiate into germ cells, little is known about the influence of culture media on this process. We investigated the effect of two culture media on the capacity of ES cells to differentiate into germ cells using embryoid body (EB) and monolayer culture protocols. Germ cell differentiation was induced in mouse ES cells under four experimental conditions: EB/Dulbecco's modified Eagle's medium (EB/DMEM), EB/knockout Dulbecco's modified Eagle's medium (EB/KO-DMEM), monolayer/Dulbecco's modified Eagle's medium (monolayer/DMEM), and monolayer/knockout Dulbecco's modified Eagle's medium (monolayer/KO-DMEM). After incubation for 6 days, quantitative real-time polymerase chain reaction (qRT-PCR) was used to assess expression of the germ cell markers, Mvh, Oct4, Rec8, Scp1, Scp3 and Stra8. Also, Oct4 and Mvh expressions at the protein level were assessed using immunocytochemistry; we evaluated alkaline phosphatase activity in addition to cell number and viability. Germ cell-specific marker expression was increased significantly in cells differentiated in KO-DMEM for both EB and monolayer protocols; the highest level was in cultures using the EB protocol. The highest cell proliferation rate was observed using the monolayer/KO-DMEM protocol and the lowest using the EB/DMEM protocol. Generally, KO-DMEM exhibited the greatest impact on germ cell differentiation and cell proliferation. Optimization of germ cell differentiation of ES cells requires careful selection of culture medium.

Endogenous, very small embryonic-like stem cells: critical review, therapeutic potential and a look ahead

BACKGROUND

Both pluripotent very small embryonic-like stem cells (VSELs) and induced pluripotent stem (iPS) cells were reported in 2006. In 2012, a Nobel Prize was awarded for iPS technology whereas even today the very existence of VSELs is not well accepted. The underlying reason is that VSELs exist in low numbers, remain dormant under homeostatic conditions, are very small in size and do not pellet down at 250-280g. The VSELs maintain life-long tissue homeostasis, serve as a backup pool for adult stem cells and are mobilized under stress conditions. An imbalance in VSELs function (uncontrolled proliferation) may result in cancer.

SEARCH METHODS

The electronic database 'Medline/Pubmed' was systematically searched with the subject heading term 'very small embryonic-like stem cells'.

OBJECTIVE AND RATIONALE

The most primitive stem cells that undergo asymmetric cell divisions to self-renew and give rise to progenitors still remain elusive in the hematopoietic system and testes, while the presence of stem cells in ovary is still being debated. We propose to review the available literature on VSELs, the methods of their isolation and characterization, their ontogeny, how they compare with embryonic stem (ES) cells, primordial germ cells (PGCs) and iPS cells, and their role in maintaining tissue homeostasis. The review includes a look ahead on how VSELs will result in paradigm shifts in basic reproductive biology.

OUTCOMES

Adult tissue-specific stem cells including hematopoietic, spermatogonial, ovarian and mesenchymal stem cells have good proliferation potential and are indeed committed progenitors (with cytoplasmic OCT-4), which arise by asymmetric cell divisions of pluripotent VSELs (with nuclear OCT-4). VSELs are the most primitive stem cells and postulated to be an overlapping population with the PGCs. Rather than migrating only to the gonads, PGCs migrate and survive in various adult body organs throughout life as VSELs. VSELs express both pluripotent and PGC-specific markers and are epigenetically and developmentally more mature compared with ES cells obtained from the inner cell mass of a blastocyst-stage embryo. As a result, VSELs readily differentiate into three embryonic germ layers and spontaneously give rise to both sperm and oocytes in vitro. Like PGCs, VSELs do not divide readily in culture, nor produce teratoma or integrate in the developing embryo. But this property of being relatively quiescent allows endogenous VSELs to survive various kinds of toxic insults. VSELs that survive oncotherapy can be targeted to induce endogenous regeneration of non-functional gonads. Transplanting healthy niche (mesenchymal) cells have resulted in improved gonadal function and live births.

WIDER IMPLICATIONS

Being quiescent, VSELs possibly do not accumulate genomic (nuclear or mitochondrial) mutations and thus may be ideal endogenous, pluripotent stem cell candidates for regenerative and reproductive medicine. The presence of VSELs in adult gonads and the fact that they survive oncotherapy may obviate the need to bank gonadal tissue for fertility preservation prior to oncotherapy. VSELs and their ability to undergo spermatogenesis/neo-oogenesis in the presence of a healthy niche will help identify newer strategies toward fertility restoration in cancer survivors, delaying menopause and also enabling aged mothers to have better quality eggs.

An oncofetal and developmental perspective on testicular germ cell cancer

Germ cell tumors (GCTs) represent a diverse group of tumors presumably originating from (early fetal) developing germ cells. Most frequent are the testicular germ cell cancers (TGCC). Overall, TGCC is the most frequent malignancy in Caucasian males (20-40 years) and remains an important cause of (treatment related) mortality in these young men. The strong association between the phenotype of TGCC stem cell components and their totipotent ancestor (fetal primordial germ cell or gonocyte) makes these tumors highly relevant from an onco-fetal point of view. This review subsequently discusses the evidence for the early embryonic origin of TGCCs, followed by an overview of the crucial association between TGCC pathogenesis, genetics, environmental exposure and the (fetal) testicular micro-environment (genvironment). This culminates in an evaluation of three genvironmentally modulated hallmarks of TGCC directly related to the oncofetal pathogenesis of TGCC: (1) maintenance of pluripotency, (2) cell cycle control/cisplatin sensitivity and (3) regulation of proliferation/migration/apoptosis by KIT-KITL mediated receptor tyrosine kinase signaling. Briefly, TGCC exhibit identifiable stem cell components (seminoma and embryonal carcinoma) and progenitors that show large and consistent similarities to primordial/embryonic germ cells, their presumed totipotent cells of origin. TGCC pathogenesis depends crucially on a complex interaction of genetic and (micro-)environmental, i.e. genvironmental risk factors that have only been partly elucidated despite significant effort. TGCC stem cell components also show a high degree of similarity with embryonic stem/germ cells (ES) in the regulation of pluripotency and cell cycle control, directly related to their exquisite sensitivity to DNA damaging agents (e.g. cisplatin). Of note, (ES specific) micro-RNAs play a pivotal role in the crossover between cell cycle control, pluripotency and chemosensitivity. Moreover, multiple consistent observations reported TGCC to be associated with KIT-KITL mediated receptor tyrosine kinase signaling, a pathway crucially implicated in proliferation, migration and survival during embryogenesis including germ cell development. In conclusion, TGCCs are a fascinating model for onco-fetal developmental processes especially with regard to studying cell cycle control, pluripotency maintenance and KIT-KITL signaling. The knowledge presented here contributes to better understanding of the molecular characteristics of TGCC pathogenesis, translating to identification of at risk individuals and enhanced quality of care for TGCC patients (diagnosis, treatment and follow-up).

Clinical significance of POU5F1P1 rs10505477 polymorphism in Chinese gastric cancer patients receving cisplatin-based chemotherapy after surgical resection

This study aimed to investigate the association between POU class5 homeobox 1 pseudogene 1 gene (POU5F1P1) rs10505477 polymorphism and the prognosis of Chinese gastric cancer patients, who received cisplatin-based chemotherapy after surgical resection. POU5F1P1 rs10505477 was genotyped using the SNaPshot method in 944 gastric cancer patients who received gastrectomy. The association of rs10505477 G > A polymorphism with the progression and prognosis in gastric cancer patients was statistically analyzed using the SPSS version 18.0 for Windows. The results reveal that rs10505477 polymorphism has a negatively effect on the overall survival of gastric cancer patients in cisplatin-based chemotherapy subgroup (HR = 1.764, 95% CI = 1.069–2.911, p = 0.023). Our preliminary study indicates for the first time that POU5F1P1 rs10505477 is correlated with survival of gastric cancer patients who receving cisplatin-based chemotherapy after gastrectomy. Further studies are warranted to investigate the mechanism and to verify our results in different populations.

Association of differential β-catenin expression with Oct-4 and Nanog in oral squamous cell carcinoma and their correlation with clinicopathological factors and prognosis

BACKGROUND

The re-expression of pluripotent markers (Oct-4 and Nanog) and the reactivation of stem cell-related pathways in oral carcinoma have been well researched. However, the relationship between the stem cell signaling molecule β-catenin and pluripotent markers Oct-4 and Nanog in oral cancer is yet to be studied in detail. Therefore, we have investigated the correlation among Oct-4, Nanog, and β-catenin in oral squamous cell carcinoma, which, in turn, could provide valuable insight into its prognostic significance.

METHODS

The immunohistochemical analysis was performed for 60 cases of oral cancer to study the expression pattern of Oct-4, Nanog, and β-catenin. Whereas immunofluorescence analysis was used to investigate the co-localization of β-catenin with Oct-4 and Nanog in oral carcinoma tissues and H314 cell line. Finally, co-immunoprecipitation analysis was used to study the possible interaction between β-catenin and Oct-4 in oral carcinoma cells.

RESULTS

β-catenin, Oct-4, and Nanog showed significant correlation with lymph node metastasis, stage, grade, and prognosis in oral squamous cell carcinoma. Interestingly, a significant positive correlation was found among the expression of Oct-4, Nanog, and β-catenin. Moreover, the interaction between β-catenin and Oct-4 was observed in oral cancer.

CONCLUSION

The positive correlation among Oct-4, Nanog, and β-catenin suggests their coordinated role in maintaining proliferation in oral carcinoma cells. The interaction between β-catenin and Oct-4 may be a crucial event in oral carcinogenesis. On the other hand, β-catenin, Oct-4, and Nanog could be used as independent prognostic markers of oral squamous cell carcinoma.

Choriogonadotropin positive seminoma-a clinicopathological and molecular genetic study of 15 cases

The presence of human chorionic gonadotropin (hCG) positive syncytiotrophoblastic cells (STC) in classic seminoma (CS) is well documented. CS with extensive hCG positive, non-syncytiotrophoblastic tumour cells (without STC) is exceptionally rare. In this study, we present 15 such cases. 168 CSs were retrieved from the Plzen Tumor registry. Cases of mixed germ cell tumors (with CS) and CSs with typical STC were excluded. Cases with completely embedded tumor mass were selected for further study and immunohistochemically examined with anti-hCG. Positive cases were further analyzed by reverse transcriptase polymerase chain reaction. Two groups of hCG-positive CSs were identified. Group 1 comprised 10 patients with a mean patient age of 37.7 years and mean tumor size of 4.96 cm. Eight cases were pT1 (TMN 2009) and 2 cases pT3a. Blood levels of hCG were elevated in 6 of the 10 patients preoperatively. In 2 patients the blood level of hCG was not tested. Mean follow-up period was 6.1 years. No metastatic behavior was noted. All tumors were extensively immunoreactive for hCG in more than 60% of tumor cells. The expression of hCG beta subunit (CGB)-mRNA in tumor tissue was documented. Group 2: Comprised 5 patients with a mean age was 34 years. Mean tumor size was 4.7 cm. Four cases were stage pT1 and 1 case was pT2. The mean follow-up period was 3.1 years. No metastatic behavior was noted. Preoperative blood levels of hCG were elevated in 1/5 of the patient. Strong hCG positivity was limited to scattered single tumor cells distributed throughout the entire tumor. Only weak expression of CGB mRNA was detected. We can conclude that immunohistochemical detection of expression of hCG in CS is not limited to syncytiotrophoblastic cells. In this study, we report two immunohistochemical patterns of hCG expression in classic seminomas: diffuse hCG staining in the majority of tumor cells and scattered hCG-positive cells within the tumor.

A novel variant of Oct3/4 gene in mouse embryonic stem cells

OCT4 is a highly conserved gene and plays an important role during early embryonic development and differentiation. Similar to human OCT4, mouse Oct4 gene generates variants. Oct4A is a master regulator of self-renewal in pluripotent stem cells. In this study, we have identified a novel Oct4 spliced variant, designated mouse Oct4B, encoding 3 isoforms, termed Oct4B-247aa, Oct4B-190aa and Oct4B-164aa. Furthermore, we have examined the expression pattern of these isoforms in non-pluripotent cells and their function in somatic cell reprogramming. The results revealed the isoforms 247aa, 164aa localized mainly in nucleus and 190aa expressed dotted in the cytoplasm. In contrast to Oct4A, Oct4B does not function in somatic reprogramming as that of Oct4A. Taken together, our data for first time described the intact coding sequence of mouse Oct4B and its function in somatic cell reprogramming. These findings will be important for further analysis of the epigenetic mechanisms of reprogramming and highlight the necessity of discriminating Oct4 isoforms in future stem cell research.

Recent advances in research of gastric cancer stem cells

Gastric cancer is a common malignancy of the digestive tract that has a high mortality and seriously affects people's health. At present, the pathogenesis of gastric cancer is still unclear. According to the cancer stem cell theory, cancer stem cells are malignant cells with the characteristics of normal stem cells, probably formed by the mutation of normal stem cells. Tumor stem cells have been identified in a variety of solid tumors. Recent studies have shown that the location of gastric cancer is consistent with the settlement area of stem cells, indicating that gastric cancer may be a kind of stem cells disease. In this article we will review the existence, origin, identification and separation of cancer stem cells.

Genome-wide analysis of OCT4 binding sites in glioblastoma cancer cells

OCT4, a member of the POU family of gene products, is an octamer motif-binding transcription factor. As it is known to play a crucial role in cancer processes including proliferation, invasion, and chemoradioresistance, it is important to identify the direct targets of OCT4 in living cancer cells. Here, chromatin immunoprecipitation-sequencing (ChIP-seq) was used to identify OCT4 binding sites in glioblastoma cancer cells. The results showed that 5438 OCT4 binding sites were localized in the glioblastoma cancer genome and that these sites contained a consensus sequence TTTkswTw (k=T or G, s=C or G, w=A or T), which occurred 3931 times in 2312 OCT4 binding regions. Furthermore, binding motifs of some other transcription factors were identified in OCT4 binding regions. Our results provide a valuable dataset for understanding gene regulation mechanisms underlying the function of OCT4 in glioblastoma cancer.

OCT4 gonadal gene expression related to the presence of Y-chromosome sequences in Turner syndrome

To show that in the dysgenetic gonads of 104 Turner syndrome patients no significant difference was found regarding the expression of the genes DAX1, FOG2, GATA4, OCT4, SF1, SRY, TSPY, WT1, and STRA8 compared with controls, except for genes OCT4, SRY, and TSPY in both gonads of a patient whose chromosomal constitution was 45,X/45,X,add(15)(p11). The expression analysis of genes OCT4, SRY, and TSPY in the dysgenetic gonads of Turner syndrome patients may allow introducing modifications in the microenvironment that could contributed to a malignant transformation process.

Oct4, a novel marker for human gastric cancer

BACKGROUND AND OBJECTIVE

Octamer-4 (Oct4), a transcription factor involved in regulating human embryonic stem cells (ESCs), may play a role in tumorigenesis. Since little is known about the efficacy of Oct4 as a potential biomarker for gastric cancer (GC), we investigated its expression in GC tissues and its relationship to various clinicopathological parameters.

METHODS

Primary tumor tissues and matching, adjacent non-cancerous tissues were obtained from 62 GC patients, and Oct4 expression was examined by reverse transcription-PCR (RT-PCR) and real-time PCR. Twenty biopsy specimens of atrophic gastritis and gastric ulcer individually were collected as control. To detect Oct4 expression in the paired GC and non-cancerous tissues at the protein level, Western blotting and immunohistochemistry (IHC) were employed. Correlation analyses were conducted to assess the relationship between Oct4 expression and clinicopathological parameters.

RESULTS

Oct4 expression levels were higher in GC tissues compared to matching, adjacent non-cancerous tissues, atrophic gastritis and gastric ulcer tissues. Additionally, Oct4 expression in GC tumors correlated with their differentiation status, but not with patient age or gender, tumor size, TNM stage, depth of invasion, or the presence of lymph node metastasis.

CONCLUSIONS

Oct4 may be a potential biomarker for the initiation, progression, and differentiation of human GC.

Implication of human OCT4 transactivation domains for self-regulatory transcription

OCT4 plays a crucial role in pluripotency and self-renewal of embryonic stem cells. OCT4 is also expressed in testicular germ cell tumors (GCTs), suggesting the important function of OCT4 as an oncogenic factor in GCTs. To understand the molecular mechanism of human OCT4 (hOCT4) in tumorigenesis as well as stemness, we identified hOCT4 transactivation domains in human embryonic carcinoma cells. Context analyses of heterologous GAL4 and natural hOCT4 revealed that each N-terminal domain or C-terminal domain independently stimulated transcriptional activity, and that both domains are required for synergistic transactivation by deletion mapping analysis. Dose-dependent overexpression of exogenous hOCT4 significantly decreased the transcriptional activity of the hOCT4 promoter. This inhibition was reversed by the removal of one or both domains. These results suggest that the inhibitory effect of hOCT4 is mediated by transactivation domains, and that the self-regulation of hOCT4 may be mediated via a negative feedback loop in pluripotent cells.

Human diseased arteries contain cells expressing leukocytic and embryonic stem cell markers

Recent evidence suggests that smooth muscle cells within the intima of diseased human blood vessels of the elderly population contain the embryonic form of smooth muscle cells. We wanted to explore the idea that human diseased vessels may contain other primitive cell types, such as pluripotent embryonic stem cells and hematopoietic stem cells. Radial and internal mammary arteries were collected from patients undergoing coronary artery bypass surgery; and coronary arteries, from hearts at autopsy and transplant. Immunohistochemistry was used to identify the embryonic stem cell markers Octomer-4; stage-specific embryonic antigens 1, 3, and 4; TRA-1-60; and TRA-1-81, and the leukocytic markers CD34, CD14, CD133, and CD64 in all vessels. We found that diseased human radial arteries contained the highest numbers of cells in the media- and intima-expressing markers of embryonic and leukocytic origin compared with diseased human coronary arteries. In nondiseased human vessels (internal mammary arteries), such cells were rarely observed. Granulation tissue within the diseased human arteries contained similar cells, and the angiogenic vessel endothelial cell layer also expressed these markers. It is concluded that diseased human blood vessels contain cells that express markers from leukocytic and embryonic origin. These results suggest that cells within human arteries might be able to differentiate into various cell types and that blood vessels might be a reservoir for such cells.