SOX4 interacts with plakoglobin in a Wnt3a-dependent manner in prostate cancer cells

A pan-cancer analysis of the expression and molecular mechanism of DHX9 in human cancers

Finding new targets is necessary for understanding tumorigenesis and developing cancer therapeutics. DExH-box helicase 9 (DHX9) plays a central role in many cellular processes but its expression pattern and prognostic value in most types of cancer remain unclear. In this study, we extracted pan-cancer data from TCGA and GEO databases to explore the prognostic and immunological role of DHX9. The expression levels of DHX9 were then verified in tumor specimens by western blot and immunohistochemistry (IHC). The oncogenic roles of DHX9 in cancers were further verified by in vitro experiments. We first verified that DHX9 is highly expressed in most tumors but significantly decreased in kidney and thyroid cancers, and it is prominently correlated with the prognosis of patients with different tumors. The phosphorylation level of DHX9 was also increased in cancers. Enrichment analysis revealed that DHX9 was involved in Spliceosome, RNA transport and mRNA surveillance pathway. Furthermore, DHX9 expression exhibited strong correlations with immune cell infiltration, immune checkpoint genes, and tumor mutational burden (TMB)/microsatellite instability (MSI). In liver, lung, breast and renal cancer cells, the knockdown or depletion of DHX9 significantly affected the proliferation, metastasis and EMT process of cancer cells. In summary, this pan-cancer investigation provides a comprehensive understanding of the prognostic and immunological role of DHX9 in human cancers, and experiments indicated that DHX9 was a potential target for cancer treatment.

Hsa-miR-133a-3p, miR-1-3p, GOLPH3 and JUP combination results in a good biomarker to distinguish between prostate cancer and non-prostate cancer patients

The incidence and mortality of Prostate Cancer (PCa) worldwide correlate with age and bad dietary habits. Previously, we investigated the mRNA/miRNA role on PCa development and progression using high fat diet (HFD) fed mice. Here our main goal was to investigate the effect of HFD on the expression of PCa-related miRNAs and their relevance in PCa patients. We identified 6 up- and 18 down-regulated miRNAs in TRAMP-C1 mice prostate tumors under HFD conditions using miRNA microarrays. Three down-regulated miRNAs: mmu-miR-133a-3p, -1a-3p and -29c-3p were validated in TRAMP-C1 mice prostate tumor by stem-loop RT-qPCR. Hsa-miR-133a-3p/1-3p expression levels were significantly decreased in PCa compared to normal tissues while hsa-miR-133a-3p was found to be further decreased in metastatic prostate cancer tumors compared to non-metastatic PCa. We examined the promoter region of hsa-miR-133a-3p/1-3p genes and compared methylation at these loci with mature miRNA expression. We found that hsa-miR-1-2/miR-133a-1 cluster promoter hypermethylation decreased hsa-miR-133a-3p/1-3p expression in PCa. GOLPH3 and JUP, two hsa-miR-133a-3p and miR-1-3p predicted target genes, were up-regulated in PCa. ROC analysis showed that the combination of hsa-miR-133a-3p, miR-1-3p, GOLPH3 and JUP is a promising panel biomarker to distinguish between PCa and normal adjacent tissue (NAT). These results link PCa aggressiveness to the attenuation of hsa-miR-133a-3p and miR-1-3p expression by promoter hypermethylation. Hsa-miR-133a-3p and miR-1-3p down-regulation may enhance PCa aggressiveness in part by targeting GOLPH3 and JUP.

KRT13 promotes stemness and drives metastasis in breast cancer through a plakoglobin/c-Myc signaling pathway

Background

Keratins (KRTs) are intermediate filament proteins that interact with multiple regulatory proteins to initiate signaling cascades. Keratin 13 (KRT13) plays an important role in breast cancer progression and metastasis. The objective of this study is to elucidate the mechanism by which KRT13 promotes breast cancer growth and metastasis.

Methods

The function and mechanisms of KRT13 in breast cancer progression and metastasis were assessed by overexpression and knockdown followed by examination of altered behaviors in breast cancer cells and in xenograft tumor formation in mouse mammary fat pad. Human breast cancer specimens were examined by immunohistochemistry and multiplexed quantum dot labeling analysis to correlate KRT13 expression to breast cancer progression and metastasis.

Results

KRT13-overexpressing MCF7 cells displayed increased proliferation, invasion, migration and in vivo tumor growth and metastasis to bone and lung. Conversely, KRT13 knockdown inhibited the aggressive behaviors of HCC1954 cells. At the molecular level, KRT13 directly interacted with plakoglobin (PG, γ-catenin) to form complexes with desmoplakin (DSP). This complex interfered with PG expression and nuclear translocation and abrogated PG-mediated suppression of c-Myc expression, while the KRT13/PG/c-Myc signaling pathway increased epithelial to mesenchymal transition and stem cell-like phenotype. KRT13 expression in 58 human breast cancer tissues was up-regulated especially at the invasive front and in metastatic specimens (12/18) (p < 0.05). KRT13 up-regulation in primary breast cancer was associated with decreased overall patient survival.

Conclusions

This study reveals that KRT13 promotes breast cancer cell growth and metastasis via a plakoglobin/c-Myc pathway. Our findings reveal a potential novel pathway for therapeutic targeting of breast cancer progression and metastasis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-022-01502-6.

Transcription factor SOX4 facilitates BMP2-regulated gene expression during invasive trophoblast differentiation

The interplay between growth factors, signaling pathways and transcription factors during placental development is key to controlling trophoblast differentiation. Bone morphogenetic protein 2 (BMP2) has been implicated in trophoblast invasion and spiral artery remodeling during early placental development. However, the molecular mechanisms by which these are accomplished have not been fully elucidated, particularly for transcriptional regulation of key transcription factors. Here, we identified SOX4 as a direct target gene induced by BMP2 in first-trimester placental trophoblasts. Analysis of single-cell RNA-seq data from first-trimester placentas and decidua tissues revealed that SOX4 expression is mainly localized in extravillous trophoblast and decidual stromal cells. Moreover, gain- and loss-of-function approaches demonstrated that SOX4 exerts a pro-invasive role in human trophoblasts, and this effect contributes to BMP2-enhanced trophoblast invasion. Importantly, we found that SOX4 was required for BMP2-induced regulation of a subset of genes associated with cell migration and extracellular matrix organization. We also show that SOX4-dependent regulation of the BMP2 target SERPINE2 occurs via binding of SOX4 to regulatory elements such as enhancers, thereby promoting BMP2-induced trophoblast invasion. In conclusion, these findings uncover a novel mechanism involving SOX4 that shapes the BMP2-regulated transcriptional network during invasive trophoblast development.

SOX4 Serves an Oncogenic Role in the Tumourigenesis of Human Breast Adenocarcinoma by Promoting Cell Proliferation, Migration and Inhibiting Apoptosis

BACKGROUND

Breast cancer is among the most common malignant cancers worldwide, and breast adenocarcinoma in glandular tissue cells has excessive metastasis and invasion capability. However, little is known on the molecular process by which this disease develops and progresses.

OBJECTIVE

In this study, we explored the effects of sex-determining region Y-box 4 (SOX4) protein on proliferation, migration, apoptosis and tumourigenesis of breast adenocarcinoma and its possible mechanisms.

METHODS

The SOX4 overexpression or knockdown Michigan Cancer Foundation-7 (MCF-7) cell lines were established. Among the SOX4 overexpression or MCF-7 knockdown cell lines, proliferation, migration ability and apoptosis rate were detected. The expression levels of apoptosis-related proteins (Bax and Cleaved caspase-3) were analysed using Western blot. The effect of SOX4 on tumourigenesis was analysed using the clone formation assay in vitro and tumour xenograft experiment in nude mice.

RESULTS

Compared with the overexpression of control cells, proliferation and migration ability of SOX4 overexpression cells significantly increased, the apoptosis rate significantly decreased in addition to the expression levels of Bax and Cleaved caspase-3 (P < 0.05). Compared with the knockdown of control cells, proliferation and migration ability of SOX4 knockdown cells significantly decreased, and the apoptosis rate and expression levels of Bax and Cleaved caspase-3 significantly increased (P < 0.05). Clone formation and tumour growth abilities of SOX4 overexpression cells were significantly higher than those of the control cells (P < 0.05), whereas SOX4 knockdown cells had the opposite effect.

CONCLUSION

SOX4 plays an oncogenic role in breast adenocarcinoma tumourigenesis by promoting cell proliferation, migration and inhibiting apoptosis. It can be used as a potential molecular target for breast cancer gene therapy.

The enigmatic helicase DHX9 and its association with the hallmarks of cancer

Much interest has been expended lately in characterizing the association between DExH-Box helicase 9 (DHX9) dysregulation and malignant development, however, the enigmatic nature of DHX9 has caused conflict as to whether it regularly functions as an oncogene or tumor suppressor. The impact of DHX9 on malignancy appears to be cell-type specific, dependent upon the availability of binding partners and activation of inter-connected signaling pathways. Realization of DHX9's pivotal role in the development of several hallmarks of cancer has boosted the enzyme's potential as a cancer biomarker and therapeutic target, opening up novel avenues for exploring DHX9 in precision medicine applications. Our review discusses the ascribed functions of DHX9 in cancer, explores its enigmatic nature and potential as an antineoplastic target.

SOX4 activates CXCL12 in hepatocellular carcinoma cells to modulate endothelial cell migration and angiogenesis in vivo

The overexpression of SOX4 in various kinds of cancer cells was associated with poor prognosis for patients. The role of SOX4 in angiogenesis and tumor microenvironment modulation was recently documented in breast cancer but remains unclear in hepatocellular carcinoma (HCC). In our study, the clinical relevance of SOX4 overexpression in HCC and its role in the tumor microenvironment were investigated. The overexpression of SOX4 (SOX4^high) in tumor lesions was associated with higher microvessel density (P = 0.012), tumor thrombosis formation (P = 0.012), distant metastasis (P < 0.001), and an independent prognostic factor for disease-free survival in HCC patients (P = 0.048). Endogenous SOX4 knockout in Hep3B cells by the CRISPR/cas9 system reduced the expression of CXCL12, which, in turn, attenuated chemotaxis in human umbilical vein endothelial cells, tube formation in vitro, reduced tumor growth, reticular fiber production, and angiogenesis in vivo in a xenograft mouse model. Treatment with an antagonist targeting CXCR4 (AMD3100), a receptor of CXCL12, inhibited chemotaxis and tube formation in endothelial cells in vitro. The CXCL12 promoter was activated by ectopic expression of a Flag-tagged SOX4 plasmid, endogenous SOX4 knockdown abolished promoter activity of CXCL12 as shown by luciferase assays, and an association with the CXCL12 promoter was identified via chromatin immunoprecipitation in HCC cells. In conclusion, SOX4 modulates the CXCL12 promoter in HCC cells. The secretory CXCL12, in turn, modulates CXCR4 in endothelial cells, reticular fibers to regulate the tumor microenvironment and modulate neovascularization, which might contribute to the distant metastasis of tumors.

The Long Noncoding RNA LINC00908 Facilitates Hepatocellular Carcinoma Progression Via Interaction With Sox-4

Background

The hepatocellular carcinoma (HCC) is a highly aggressive and common malignancy worldwide. Accumulating evidence has demonstrated a pivotal role of long noncoding RNAs (lncRNAs) in various tumors. However, the function of intergenic lncRNA LINC00908 is still unknown in HCC.

Methods

The RT-qPCR method was used to quantify the expression of LINC00908. Migration and viability assay were performed to evaluate the in vitro effect and xenograft tumor model was used to measure the in vivo effect. Immunoblot was used to identify the association of LINC00908 with Sox-4 and the stability of Sox-4.

Results

We found a novel lncRNA related to HCC. LINC00908 is highly expressed in tumorous tissues and cell lines compared with normal ones. High LINC00908 expression correlated with advanced TNM stages, tumor size and metastasis. LINC00908 promoted the migration and viability of HCC cells. The in vivo xenograft tumor growth and proliferation were also enhanced by LINC00908 overexpression and inhibited by LINC00908 silence. LINC00908 physically interacted with Sox-4, and the association between LINC00908 and Sox-4 increased the stability of Sox-4 by reducing proteasomal degradation.

Conclusion

Taken together, our current work has identified a novel lncRNA LINC00908 which is critically involved in HCC progression. The LINC00908-Sox-4 axis might provide a new and potential target for pharmaceutical therapies.

SOX4: The unappreciated oncogene

SOX4 is an essential developmental transcription factor that regulates stemness, differentiation, progenitor development, and multiple developmental pathways including PI3K, Wnt, and TGFβ signaling. The SOX4 gene is frequently amplified and overexpressed in over 20 types of malignancies, and multiple lines of evidence support that notion that SOX4 is an oncogene. Its overexpression is due to both gene amplification and to activation of PI3K, Wnt, and TGFβ pathways that SOX4 regulates. SOX4 interacts with multiple other transcription factors, rendering many of its impacts on gene expression context and tissue-specific. Nevertheless, there are common themes that run through many of the effects of SOX4 hyperactivity, such as the promotion of cell survival, stemness, the epithelial to mesenchymal transition, migration, and metastasis. Specific targeting of SOX4 remains a challenge for future cancer research and drug development.

SOX4 regulates invasion of bladder cancer cells via repression of WNT5a

Sry-Related HMG-BOX-4 (SOX4) is a developmental transcription factor that is overexpressed in as many as 23% of bladder cancer patients; however, the role of SOX4 in bladder cancer tumorigenesis is not yet well understood. Given the many roles of SOX4 in embryonic development and the context-dependent regulation of gene expression, in this study, we sought to determine the role of SOX4 in bladder cancer and to identify SOX4-regulated genes that may contribute to tumorigenesis. For this purpose, we employed a CRISPR interference (CRISPRi) method to transcriptionally repress SOX4 expression in T24 bladder cancer cell lines, 'rescued' these cell lines with the lentiviral-mediated expression of SOX4, and performed whole genome expression profiling. The cells in which SOX4 was knocked down (T24-SOX4-KD) exhibited decreased invasive capabilities, but no changes in migration or proliferation, whereas rescue experiments with SOX4 lentiviral vector restored the invasive phenotype. Gene expression profiling revealed 173 high confidence SOX4-regulated genes, including WNT5a as a potential target of repression by SOX4. Treatment of the T24-SOX4-KD cells with a WNT5a antagonist restored the invasive phenotype observed in the T24-scramble control cells and the SOX4 lentiviral-rescued cells. High WNT5a expression was associated with a decreased invasion and WNT5a expression inversely correlated with SOX4 expression, suggesting that SOX4 can negatively regulate WNT5a levels either directly or indirectly and that WNT5a likely plays a protective role against invasion in bladder cancer cells.

Role of Wnt3a in the pathogenesis of cancer, current status and prospective

The Wnt signaling pathway plays a critical role in initiation, progression, invasion and metastasis of cancer. Wnt3a as a canonical Wnt ligand is strongly implicated in the etiology and pathology of a number of diseases including cancer. Depending on cancer type, Wnt3a enhances or suppresses metastasis, cell proliferation and apoptosis of cancer cells. This review summarizes the role of Wnt3a in the pathogenesis of different cancers including colorectal, prostate, hepatocellular, lung and leukemia, for promoting greater understanding and clinical management of these diseases.

Identification of testicular cancer driver genes by a cross-species comparative oncology approach

BACKGROUND

Germ cell tumors arise in the testis, ovary, or extragonadal locations and have a wide range of histopathological and clinical presentations. The relative lack of animal models of germ cell tumors has impeded functional assessment of candidate driver genes. Previously, we described the development of testicular germ cell tumors in zebrafish carrying a mutation in bmpr1bb, a BMP family receptor, and demonstrated that human germ cell tumors have defects in BMP signaling.

OBJECTIVE

To further credential the zebrafish model for studies of human germ cell tumor, and to elucidate conserved genetic programs underlying the development of germ cell tumor.

MATERIALS AND METHODS

We used genetic techniques to ablate the germ cell lineage in developing fish and tested tumors for loss-of-heterozygosity of the wild-type allele of bmpr1bb. We performed comparative gene expression profiling of zebrafish and human germ cell tumors and carried out functional studies of selected genes.

RESULTS

Ablation of germ cells completely prevents testis tumor formation in the fish, definitively establishing the germ cell origin of the tumors. Germ cell tumors in bmpr1bb heterozygous mutants retain the wild-type allele, indicating haploinsufficiency of bmpr1bb as the mechanism of tumor formation. Comparison of RNA-Seq and microarray data from human and zebrafish germ cell tumors revealed a unique overlapping signature shared by the zebrafish tumors with human seminomas, yolk sac tumors, and embryonal carcinomas. The most highly conserved gene set in this cross-species analysis included potential driver genes such as JUP, which we show to be essential for germ cell tumor cell growth.

CONCLUSION

Our findings highlight the value of cross-species comparative oncology for the identification of candidate human cancer genes.

CUL4B promotes prostate cancer progression by forming positive feedback loop with SOX4

How to distinguish indolent from aggressive disease remains a great challenge in prostate cancer (PCa) management. Cullin 4B (CUL4B) is a scaffold protein and exhibits oncogenic activity in a variety of human malignancies. In this study, we utilized PCa tissue specimens, cell lines and xenograft models to determine whether CUL4B contributes to PCa progression and metastasis. Here, we show that CUL4B expression highly correlates with the aggressiveness of PCa. CUL4B expression promotes proliferation, epithelial−mesenchymal transition, and metastatic potential of PCa cells, whereas CUL4B knockdown inhibits. Mechanically, CUL4B positively regulates SOX4, a key regulator in PCa, through epigenetic silencing of miR-204. In turn, SOX4 upregulates CUL4B expression through transcriptional activation, thereby fulfilling a positive feedback loop. Clinically, CUL4B+/SOX4+ defines a subset of PCa patients with poor prognosis. Bioinformatics analysis further reveals that Wnt/ß-catenin activation signature is enriched in CUL4B+/SOX4+ patient subgroup. Intriguingly, Wnt inhibitors significantly attenuates oncogenic capacities of CUL4B in vitro and in vivo. Together, our study identifies CUL4B as a key modulator of aggressive PCa by a positive feedback loop that interacts with SOX4. This regulatory circuit may have a crucial role in PCa progression.

Phosphorylation Modulates the Subcellular Localization of SOX11

SOX11 is a key Transcription Factor (TF) in the regulation of embryonic and adult neurogenesis, whose mutation has recently been linked to an intellectual disability syndrome in humans. SOX11's transient activity during neurogenesis is critical to ensure the precise execution of the neurogenic program. Here, we report that SOX11 displays differential subcellular localizations during the course of neurogenesis. Western-Blot analysis of embryonic mouse brain lysates indicated that SOX11 is post-translationally modified by phosphorylation. Using Mass Spectrometry, we found 10 serine residues in the SOX11 protein that are putatively phosphorylated. Systematic analysis of phospho-mutant SOX11 resulted in the identification of the S30 residue, whose phosphorylation promotes nuclear over cytoplasmic localization of SOX11. Collectively, these findings uncover phosphorylation as a novel layer of regulation of the intellectual disability gene Sox11.

Plakoglobin restores tumor suppressor activity of p53R175H mutant by sequestering the oncogenic potential of β-catenin

Tumor suppressor/transcription factor p53 is mutated in over 50% of all cancers. Some mutant p53 proteins have not only lost tumor suppressor activities but they also gain oncogenic functions (GOF). One of the most frequently expressed GOF p53 mutants is Arg175His (p53R175H ) with well-documented roles in cancer development and progression. Plakoglobin is a cell adhesion and signaling protein and a paralog of β-catenin. Unlike β-catenin that has oncogenic function through its role in the Wnt pathway, plakoglobin generally acts as a tumor/metastasis suppressor. We have shown that plakoglobin interacted with wild type and a number of p53 mutants in various carcinoma cell lines. Plakoglobin and mutant p53 interacted with the promoter and regulated the expression of several p53 target genes. Furthermore, plakoglobin interactions with p53 mutants restored their tumor suppressor/metastasis activities in vitro. GOF p53 mutants induce accumulation and oncogenic activation of β-catenin. Previously, we showed that one mechanism by which plakoglobin may suppress tumorigenesis is by sequestering β-catenin's oncogenic activity. Here, we examined the effects of p53R175H expression on β-catenin accumulation and transcriptional activation and their modifications by plakoglobin coexpression. We showed that p53R175H expression in plakoglobin null cells increased total and nuclear levels of β-catenin and its transcriptional activity. Coexpression of plakoglobin in these cells promoted β-catenin's proteasomal degradation, and decreased its nuclear levels and transactivation. Wnt/β-catenin targets, c-MYC and S100A4 were upregulated in p53R175H cells and were downregulated when plakoglobin was coexpressed. Plakoglobin-p53R175H cells also showed significant reduction in their migration and invasion in vitro.

Beyond cell-cell adhesion: Plakoglobin and the regulation of tumorigenesis and metastasis

Plakoglobin (also known as? -catenin) is a member of the Armadillo family of proteins and a paralog of β -catenin. Plakoglobin is a component of both the adherens junctions and desmosomes, and therefore plays a vital role in the regulation of cell-cell adhesion. Similar to β -catenin, plakoglobin is capable of participating in cell signaling in addition to its role in cell-cell adhesion. In this context, β -catenin has a well-documented oncogenic potential as a component of the Wnt signaling pathway. In contrast, while some studies have suggested a tumor promoting activity of plakoglobin in a cell/malignancy specific context, it generally acts as a tumor/metastasis suppressor. How plakoglobin acts as a growth/metastasis inhibitory protein has remained, until recently, unclear. Recent evidence suggests that plakoglobin may suppress tumorigenesis and metastasis by multiple mechanisms, including the suppression of oncogenic signaling, interactions with various proteins involved in tumorigenesis and metastasis, and the regulation of the expression of genes involved in these processes. This review is primarily focused on various mechanisms by which plakoglobin may inhibit tumorigenesis and metastasis.

The biology of DHX9 and its potential as a therapeutic target

DHX9 is member of the DExD/H-box family of helicases with a “DEIH” sequence at its eponymous DExH-box motif. Initially purified from human and bovine cells and identified as a homologue of the Drosophila Maleless (MLE) protein, it is an NTP-dependent helicase consisting of a conserved helicase core domain, two double-stranded RNA-binding domains at the N-terminus, and a nuclear transport domain and a single-stranded DNA-binding RGG-box at the C-terminus. With an ability to unwind DNA and RNA duplexes, as well as more complex nucleic acid structures, DHX9 appears to play a central role in many cellular processes. Its functions include regulation of DNA replication, transcription, translation, microRNA biogenesis, RNA processing and transport, and maintenance of genomic stability. Because of its central role in gene regulation and RNA metabolism, there are growing implications for DHX9 in human diseases and their treatment. This review will provide an overview of the structure, biochemistry, and biology of DHX9, its role in cancer and other human diseases, and the possibility of targeting DHX9 in chemotherapy.

The physical interaction of p53 and plakoglobin is necessary for their synergistic inhibition of migration and invasion

Plakoglobin (PG) is a paralog of β-catenin with similar adhesive, but contrasting signalling functions. Although β-catenin has well-known oncogenic function, PG generally acts as a tumor/metastasis suppressor by mechanisms that are just beginning to be deciphered. Previously, we showed that PG interacted with wild type (WT) and a number of mutant p53s, and that its tumor/metastasis suppressor activity may be mediated, at least partially, by this interaction. Here, carcinoma cell lines deficient in both p53 and PG (H1299), or expressing mutant p53 in the absence of PG (SCC9), were transfected with expression constructs encoding WT and different fragments and deletions of p53 and PG, individually or in pairs. Transfectants were characterized for their in vitro growth, migratory and invasive properties and for mapping the interacting domain of p53 and PG. We showed that when coexpressed, p53-WT and PG-WT cooperated to decrease growth, and acted synergistically to significantly reduce cell migration and invasion. The DNA-binding domain of p53 and C-terminal domain of PG mediated p53/PG interaction, and furthermore, the C-terminus of PG played a central role in the inhibition of invasion in association with p53.

ChIP-seq analysis of genomic binding regions of five major transcription factors highlights a central role for ZIC2 in the mouse epiblast stem cell gene regulatory network

To obtain insight into the transcription factor (TF)-dependent regulation of epiblast stem cells (EpiSCs), we performed ChIP-seq analysis of the genomic binding regions of five major TFs. Analysis of in vivo biotinylated ZIC2, OTX2, SOX2, POU5F1 and POU3F1 binding in EpiSCs identified several new features. (1) Megabase-scale genomic domains rich in ZIC2 peaks and genes alternate with those rich in POU3F1 but sparse in genes, reflecting the clustering of regulatory regions that act at short and long-range, which involve binding of ZIC2 and POU3F1, respectively. (2) The enhancers bound by ZIC2 and OTX2 prominently regulate TF genes in EpiSCs. (3) The binding sites for SOX2 and POU5F1 in mouse embryonic stem cells (ESCs) and EpiSCs are divergent, reflecting the shift in the major acting TFs from SOX2/POU5F1 in ESCs to OTX2/ZIC2 in EpiSCs. (4) This shift in the major acting TFs appears to be primed by binding of ZIC2 in ESCs at relevant genomic positions that later function as enhancers following the disengagement of SOX2/POU5F1 from major regulatory functions and subsequent binding by OTX2. These new insights into EpiSC gene regulatory networks gained from this study are highly relevant to early stage embryogenesis.

RNA helicase DHX9 may be a therapeutic target in lung cancer and inhibited by enoxacin

RNA helicase DHX9 is a member of human RNA enzymes. Previous studies have reported that DHX9 is highly expressed in various types of malignant tumor. However, its role in the progression of lung cancer remains to be fully clarified. The present study aims to investigate the oncogenic role of DHX9 in serum, tissues and lung cancer cell lines in vitro. We used RNA interference to downregulate DHX9 expression in A549 cells using a small interfering RNA lentiviral vector. Subsequently, enoxacin was used to inhibit cell proliferation, and this effect was detected using MTT. The results showed that DHX9 was overexpressed in the serum and tissues of lung cancer, especially in small cell lung cancer. Though enoxacin suppressed the proliferation of NSCLC cells, the inhibition effect was diminished when DHX9 was knocked down. In conclusion, the present study provided evidence suggesting that DHX9 was overexpressed in lung cancer and may contribute to the growth of lung cancer, and enoxacin may inhibit the proliferation based on DHX9. Thus DHX9 may be used as a diagnostic marker and a potential therapeutic target for the treatment of NSCLC.

Wanted DEAD/H or Alive: Helicases Winding Up in Cancers

Cancer is one of the most studied areas of human biology over the past century. Despite having attracted much attention, hype, and investments, the search to find a cure for cancer remains an uphill battle. Recent discoveries that challenged the central dogma of molecular biology not only further increase the complexity but also demonstrate how various types of noncoding RNAs such as microRNA and long noncoding RNA, as well as their related processes such as RNA editing, are important in regulating gene expression. Parallel to this aspect, an increasing number of reports have focused on a family of proteins known as DEAD/H-box helicases involved in RNA metabolism, regulation of long and short noncoding RNAs, and novel roles as "editing helicases" and their association with cancers. This review summarizes recent findings on the roles of RNA helicases in various cancers, which are broadly classified into adult solid tumors, childhood solid tumors, leukemia, and cancer stem cells. The potential small molecule inhibitors of helicases and their therapeutic value are also discussed. In addition, analyzing next-generation sequencing data obtained from public portals and reviewing existing literature, we provide new insights on the potential of DEAD/H-box helicases to act as pharmacological drug targets in cancers.

TMEM2 Is a SOX4-Regulated Gene That Mediates Metastatic Migration and Invasion in Breast Cancer

The developmental transcription factor SOX4 contributes to the metastatic spread of multiple solid cancer types, but its direct target genes that mediate cancer progression are not well defined. Using a systematic molecular and genomic approach, we identified the TMEM2 transmembrane protein gene as a direct transcriptional target of SOX4. TMEM2 was transcriptionally activated by SOX4 in breast cancer cells where, like SOX4, TMEM2 was found to mediate proinvasive and promigratory effects. Similarly, TMEM2 was sufficient to promote metastatic colonization of breast cancer cells and its expression in primary breast tumors associated with a higher likelihood of metastatic relapse. Given earlier evidence that genetic inactivation of SOX4 or TMEM2 yield similar defects in cardiac development, our findings lead us to propose that TMEM2 may not only mediate the pathologic effects of SOX4 on cancer progression but also potentially its contributions to embryonic development. Cancer Res; 76(17); 4994-5005. ©2016 AACR.

Plakoglobin Reduces the in vitro Growth, Migration and Invasion of Ovarian Cancer Cells Expressing N-Cadherin and Mutant p53

Aberrant expression of cadherins and catenins plays pivotal roles in ovarian cancer development and progression. Plakoglobin (PG, γ-catenin) is a paralog of β-catenin with dual adhesive and signaling functions. While β-catenin has known oncogenic function, PG generally acts as a tumor/metastasis suppressor. We recently showed that PG interacted with p53 and that its growth/metastasis inhibitory function may be mediated by this interaction. Very little is known about the role of PG in ovarian cancer. Here, we investigated the in vitro tumor/metastasis suppressor effects of PG in ovarian cancer cell lines with mutant p53 expression and different cadherin profiles. We showed that the N-cadherin expressing and E-cadherin and PG deficient ES-2 cells were highly migratory and invasive, whereas OV-90 cells that express E-cadherin, PG and very little/no N-cadherin were not. Exogenous expression of PG or E-cadherin or N-cadherin knockdown in ES-2 cells (ES-2-E-cad, ES-2-PG and ES-2-shN-cad) significantly reduced their migration and invasion. Also, PG expression or N-cadherin knockdown significantly decreased ES-2 cells growth. Furthermore, PG interacted with both cadherins and with wild type and mutant p53 in normal ovarian and ES-2-PG cell lines, respectively.

In Vivo Selection Against Human Colorectal Cancer Xenografts Identifies an Aptamer That Targets RNA Helicase Protein DHX9

The ability to selectively target disease-related tissues with molecules is critical to the design of effective therapeutic and diagnostic reagents. Recognizing the differences between the in vivo environment and in vitro conditions, we employed an in vivo selection strategy to identify RNA aptamers (targeting motifs) that could localize to tumor in situ. One of the selected molecules is an aptamer that binds to the protein DHX9, an RNA helicase that is known to be upregulated in colorectal cancer. Upon systemic administration, the aptamer preferentially localized to the nucleus of cancer cells in vivo and thus has the potential to be used for targeted delivery.

Plakoglobin expression in fibroblasts and its role in idiopathic pulmonary fibrosis

Background

Idiopathic pulmonary fibrosis (IPF) is an interstitial fibrotic lung disease of unknown origin and without effective therapy characterized by deposition of extracellular matrix by activated fibroblasts in the lung. Fibroblast activation in IPF is associated with Wnt/β-catenin signaling, but little is known about the role of the β-catenin-homologous desmosomal protein, plakoglobin (PG), in IPF. The objective of this study was to assess the functional role of PG in human lung fibroblasts in IPF.

Methods

Human lung fibroblasts from normal or IPF patients were transfected with siRNA targeting PG and used to assess cellular adhesion to a fibronectin substrate, apoptosis and proliferation. Statistical analysis was performed using Student’s t-test with Mann–Whitney post-hoc analyses and results were considered significant when p < 0.05.

Results

We found that IPF lung fibroblasts expressed less PG protein than control fibroblasts, but that characteristic fibroblast phenotypes (adhesion, proliferation, and apoptosis) were not controlled by PG expression. Consistent with this, normal fibroblasts in which PG was silenced displayed no change in functional phenotype.

Conclusions

We conclude that diminished PG levels in IPF lung fibroblasts do not directly affect certain phenotypic behaviors. Further study is needed to identify the functional consequences of decreased PG in these cells.

Wnt3a: functions and implications in cancer

Wnt3a, one of Wnt family members, plays key roles in regulating pleiotropic cellular functions, including self-renewal, proliferation, differentiation, and motility. Accumulating evidence has suggested that Wnt3a promotes or suppresses tumor progression via the canonical Wnt signaling pathway depending on cancer type. In addition, the roles of Wnt3a signaling can be inhibited by multiple proteins or chemicals. Herein, we summarize the latest findings on Wnt3a as an important therapeutic target in cancer.

A New Combinatorial Optimization Approach for Integrated Feature Selection Using Different Datasets: A Prostate Cancer Transcriptomic Study

Background

The joint study of multiple datasets has become a common technique for increasing statistical power in detecting biomarkers obtained from smaller studies. The approach generally followed is based on the fact that as the total number of samples increases, we expect to have greater power to detect associations of interest. This methodology has been applied to genome-wide association and transcriptomic studies due to the availability of datasets in the public domain. While this approach is well established in biostatistics, the introduction of new combinatorial optimization models to address this issue has not been explored in depth. In this study, we introduce a new model for the integration of multiple datasets and we show its application in transcriptomics.

Methods

We propose a new combinatorial optimization problem that addresses the core issue of biomarker detection in integrated datasets. Optimal solutions for this model deliver a feature selection from a panel of prospective biomarkers. The model we propose is a generalised version of the (α,β)-k-Feature Set problem. We illustrate the performance of this new methodology via a challenging meta-analysis task involving six prostate cancer microarray datasets. The results are then compared to the popular RankProd meta-analysis tool and to what can be obtained by analysing the individual datasets by statistical and combinatorial methods alone.

Results

Application of the integrated method resulted in a more informative signature than the rank-based meta-analysis or individual dataset results, and overcomes problems arising from real world datasets. The set of genes identified is highly significant in the context of prostate cancer. The method used does not rely on homogenisation or transformation of values to a common scale, and at the same time is able to capture markers associated with subgroups of the disease.

Hepatitis B virus replication and sex-determining region Y box 4 production are tightly controlled by a novel positive feedback mechanism

Hepatitis B virus (HBV) infection is a major cause of liver diseases. However, the mechanisms underlying HBV infection and pathogenesis remain largely unknown. The sex-determining region Y box 4 (Sox4) is a transcriptional factor, which preferentially regulates the development of various organs, tissues, and cancers. But, the role of Sox4 in viral infection and pathogenesis has not been elucidated. Here, we demonstrated that Sox4 is up-regulated by HBV, and revealed the mechanism by which HBV regulates Sox4 expression. First, HBV stimulates Sox4 expression through transcriptional factor Yin Yang 1 (YY1), which binds to Sox4 promoter to activate Sox4 transcriptional activity. Second, miR-335, miR-129-2 and miR-203 inhibit Sox4 expression by targeting its mRNA 3’UTR, while HBV suppresses the microRNAs expression, resulting in up-regulating Sox4 post-transcriptionally. Third, Sox4 protein is degraded by proteasome, while HBV surface protein (HBsAg) prevents Sox4 from degradation by directly interacting with the protein, thereby enhancing Sox4 production post-translationlly. More interestingly, HBV-activated Sox4 in turn facilitates HBV replication by direct binding to the viral genome via its HMG box. Thus, this study revealed a novel positive feedback mechanism by which Sox4 production and HBV replication are tightly correlated.

Circulating tumor cell clusters-associated gene plakoglobin and breast cancer survival

Breast cancer recurrence is a major cause of the disease-specific death. Circulating tumor cells (CTCs) are negatively associated with breast cancer survival. Plakoglobin, a cell adhesion protein, was recently reported as a determinant of CTCs types, single or clustered ones. Here, we aim to summarize the studies on the roles of plakoglobin and evaluate the association of plakoglobin and breast cancer survival. Plakoglobin as a key component in both cell adhesion and the signaling pathways was briefly reviewed first. Then the double-edge functions of plakoglobin in tumors and its association with CTCs and breast cancer metastasis were introduced. Finally, based on an open-access database, the association between plakoglobin and breast cancer survival was investigated using univariate and multivariate survival analyses. Plakoglobin may be a molecule functioning as a double-edge sword. Loss of plakoglobin expression leads to increased motility of epithelial cells, thereby promoting epithelial-mesenchymal transition and further metastasis of cancer. However, studies also show that plakoglobin can function as an oncogene. High expression of plakoglobin results in clustered tumor cells in circulation with high metastatic potential in breast cancer and shortened patient survival. Plakoglobin may be a potential prognostic biomarker that can be exploited to develop as a therapeutic target for breast cancer.

Inherited desmosomal disorders

Desmosomes serve as intercellular junctions in various tissues including the skin and the heart where they play a crucial role in cell-cell adhesion, signalling and differentiation. The desmosomes connect the cell surface to the keratin cytoskeleton and are composed of a transmembranal part consisting mainly of desmosomal cadherins, armadillo proteins and desmoplakin, which form the intracytoplasmic desmosomal plaque. Desmosomal genodermatoses are caused by mutations in genes encoding the various desmosomal components. They are characterized by skin, hair and cardiac manifestations occurring in diverse combinations. Their classification into a separate and distinct clinical group not only recognizes their common pathogenesis and facilitates their diagnosis but might also in the future form the basis for the design of novel and targeted therapies for these occasionally life-threatening diseases.

SOXC proteins amplify canonical WNT signaling to secure nonchondrocytic fates in skeletogenesis

In skeletogenic mesenchyme, SOXC proteins enter the APC–Axin destruction complex to inhibit β-catenin phosphorylation by GSK3 and thereby synergize with canonical WNT signaling to inhibit chondrogenesis.

Canonical WNT signaling stabilizes β-catenin to determine cell fate in many processes from development onwards. One of its main roles in skeletogenesis is to antagonize the chondrogenic transcription factor SOX9. We here identify the SOXC proteins as potent amplifiers of this pathway. The SOXC genes, i.e., Sox4, Sox11, and Sox12, are coexpressed in skeletogenic mesenchyme, including presumptive joints and perichondrium, but not in cartilage. Their inactivation in mouse embryo limb bud caused massive cartilage fusions, as joint and perichondrium cells underwent chondrogenesis. SOXC proteins govern these cells cell autonomously. They replace SOX9 in the adenomatous polyposis coli–Axin destruction complex and therein inhibit phosphorylation of β-catenin by GSK3. This inhibition, a crucial, limiting step in canonical WNT signaling, thus becomes a constitutive event. The resulting SOXC/canonical WNT-mediated synergistic stabilization of β-catenin contributes to efficient repression of Sox9 in presumptive joint and perichondrium cells and thereby ensures proper delineation and articulation of skeletal primordia. This synergy may determine cell fate in many processes besides skeletogenesis.

Mutation of murine Sox4 untranslated regions results in partially penetrant perinatal lethality

BACKGROUND

Sox4 is an essential gene, and genetic deletion results in embryonic lethality. In an effort to develop mice with tissue-specific deletion, we bred conditional knockout mice bearing LoxP recombination sites flanking the Sox4 gene, with the LoxP sites located in the Sox4 5'UTR and 3'UTR.

RESULTS

The number of mice homozygous for this LoxP-flanked conditional knockout allele was far below the expected number, suggesting embryonic lethality with reduced penetrance. From over 200 animals bred, only 11% were homozygous Sox4(flox/flox) mice, compared to the expected Mendelian ratio of 25% (p<0.001). Moreover, there was a significant reduction in the number of female Sox4(flox/flox) mice (26%) relative to male Sox4(flox/flox) mice (p=0.0371). Reduced Sox4 expression in homozygous embryos was confirmed by in-situ hybridization and Quantitative real-time polymerase chain reaction (QPCR).

CONCLUSION

LoxP sites in the 5' and 3' UTR of both alleles of Sox4 resulted in reduced, but variable expression of Sox4 message.

Structural and functional diversity of desmosomes

Desmosomes anchor intermediate filaments at sites of cell contact established by the interaction of cadherins extending from opposing cells. The incorporation of cadherins, catenin adaptors, and cytoskeletal elements resembles the closely related adherens junction. However, the recruitment of intermediate filaments distinguishes desmosomes and imparts a unique function. By linking the load-bearing intermediate filaments of neighboring cells, desmosomes create mechanically contiguous cell sheets and, in so doing, confer structural integrity to the tissues they populate. This trait and a well-established role in human disease have long captured the attention of cell biologists, as evidenced by a publication record dating back to the mid-1860s. Likewise, emerging data implicating the desmosome in signaling events pertinent to organismal development, carcinogenesis, and genetic disorders will secure a prominent role for desmosomes in future biological and biomedical investigations.

Growth inhibitory effects of three miR-129 family members on gastric cancer

Reduced expression of microRNA-129 (miR-129) has been reported in several types of tumor cell lines as well as in primary tumor tissues. However, little is known about how miR-129 affects cell proliferation in gastric cancer. Here, we show that all miR-129 family members, miR-129-1-3p, miR-129-2-3p, and miR-129-5p, are down-regulated in gastric cancer cell lines compared with normal gastric epithelial cells. Furthermore, using the real-time cell analyzer assay to observe the growth effects of miR-129 on gastric cancer cells, we found that all three mature products of miR-129 showed tumor suppressor activities. To elucidate the molecular mechanisms underlying down-regulation of miR-129 in gastric cancer, we analyzed the effects of miR-129 mimics on the cell cycle. We found that increased miR-129 levels in gastric cancer cells resulted in significant G0/G1 phase arrest. Interestingly, we showed that cyclin dependent kinase 6 (CDK6), a cell cycle-associated protein involved in G1-S transition, was a target of miR-129. We also found that expression of the sex determining region Y-box 4 (SOX4) was inversely associated with that of miR-129-2-3p and miR-129-5p but not of miR-129-1-3p. Together, our data indicate that all miR-129 family members, not only miR-129-5p, as previously thought, play an important role in regulating cell proliferation in gastric cancer.

Pleiotropic function of SRY-related HMG box transcription factor 4 in regulation of tumorigenesis

In addition to their critical roles in embryonic development, cell fate decision, and differentiation, members of Sox (Sry-related high-mobility group box) family of transcription factors including Sox4 have been implicated in various cancers. Multiple studies have revealed an increased expression along with specific oncogenic function of Sox4 in tumors, while others observed a reduced expression of Sox4 in different types of malignancies and suppression of tumor initiation or progression by this protein. More interestingly, the prognostic value of Sox4 is debated due to obvious differences between various reports as well as inconsistencies within specific studies. This review summarizes our current understanding of Sox4 expression pattern and its transcription-dependent, as well as transcription-independent, functions in tumor initiation or progression and its correlation with patient survival. We also discuss the existing discrepancies between different reports and their possible explanations.

Plakoglobin interacts with the transcription factor p53 and regulates the expression of 14-3-3σ

Plakoglobin (γ-catenin), a constituent of the adherens junction and desmosomes, has signaling capabilities typically associated with tumor/metastasis suppression through mechanisms that remain undefined. To determine the role of plakoglobin during tumorigenesis and metastasis, we expressed plakoglobin in human tongue squamous cell carcinoma (SCC9) cells and compared the mRNA profiles of parental SCC9 cells and their plakoglobin-expressing transfectants (SCC9-PG). We detected several p53-target genes whose levels were altered upon plakoglobin expression. In this study, we identified the p53 regulated tumor suppressor 14-3-3σ as a direct plakoglobin-p53 target gene. Coimmunoprecipitation experiments revealed that plakoglobin and p53 interact, and chromatin immunoprecipitation and electrophoretic mobility shift assays revealed that plakoglobin and p53 associate with the 14-3-3σ promoter. Furthermore, luciferase reporter assays showed that p53 transcriptional activity is increased in the presence of plakoglobin. Finally, knockdown of plakoglobin in MCF-7 cells followed by luciferase assays confirmed that p53 transcriptional activity is enhanced in the presence of plakoglobin. Our data suggest that plakoglobin regulates gene expression in conjunction with p53 and that plakoglobin may regulate p53 transcriptional activity, which may account, in part, for the tumor/metastasis suppressor activity of plakoglobin.

The role of proteomics in prostate cancer research: biomarker discovery and validation

PURPOSE

Prostate Cancer (PCa) represents the second most frequent type of tumor in men worldwide. Incidence increases with patient age and represents the most important risk factor. PCa is mostly characterized by indolence, however in a small percentage of cases (3%) the disease progresses to a metastatic state. To date, the most important issue concerning PCa research is the difficulty in distinguishing indolent from aggressive disease. This problem frequently results in low-grade PCa patient overtreatment and, in parallel; an effective treatment for distant and aggressive disease is not yet available.

RESULT

Proteomics represents a promising approach for the discovery of new biomarkers able to improve the management of PCa patients. Markers more specific and sensitive than PSA are needed for PCa diagnosis, prognosis and response to treatment. Moreover, proteomics could represent an important tool to identify new molecular targets for PCa tailored therapy. Several possible PCa biomarkers sources, each with advantages and limitations, are under investigation, including tissues, urine, serum, plasma and prostatic fluids. Innovative high-throughput proteomic platforms are now identifying and quantifying new specific and sensitive biomarkers for PCa detection, stratification and treatment. Nevertheless, many putative biomarkers are still far from being applied in clinical practice.

CONCLUSIONS

This review aims to discuss the recent advances in PCa proteomics, emphasizing biomarker discovery and their application to clinical utility for diagnosis and patient stratification.

The role of SRY-related HMG box transcription factor 4 (SOX4) in tumorigenesis and metastasis: friend or foe?

Development and progression of cancer are mediated by alterations in transcriptional networks, resulting in a disturbed balance between the activity of oncogenes and tumor suppressor genes. Transcription factors have the capacity to regulate global transcriptional profiles, and are consequently often found to be deregulated in their expression and function during tumorigenesis. Sex-determining region Y-related high-mobility-group box transcription factor 4 (SOX4) is a member of the group C subfamily of the SOX transcription factors and has a critical role during embryogenesis, where its expression is widespread and controls the development of numerous tissues. SOX4 expression is elevated in a wide variety of tumors, including leukemia, colorectal cancer, lung cancer and breast cancer, suggesting a fundamental role in the development of these malignancies. In many cancers, deregulated expression of this developmental factor has been correlated with increased cancer cell proliferation, cell survival, inhibition of apoptosis and tumor progression through the induction of an epithelial-to-mesenchymal transition and metastasis. However, in a limited subset of tumors, SOX4 has also been reported to act as a tumor suppressor. These opposing roles suggest that the outcome of SOX4 activation depends on the cellular context and the tumor origin. Indeed, SOX4 expression, transcriptional activity and target gene specificity can be controlled by signaling pathways, including the transforming growth factor-β and the WNT pathway, as well as at the post-translational level through regulation of protein stability and interaction with specific cofactors, such as TCF, syntenin-1 and p53. Here, we provide an overview of our current knowledge concerning the role of SOX4 in tumor development and progression.

Clinicopathological significance of SOX4 expression in primary gallbladder carcinoma

Aim

SOX4, as a member of the SRY-related HMG-box (SOX) transcription factor family, has been demonstrated to be involved in tumorigenesis of many human malignancies; however, its role in primary gallbladder carcinoma (PGC) is still largely unknown. The aim of this study was to investigate SOX4 expression in PGC and its prognostic significance.

Methods

From 1997 to 2006, 136 patients underwent resection for PGC. The median follow-up was 12.8 months. Immunostainings for SOX4 were performed on these archival tissues. The correlation of SOX4 expression with clinicopathological features including survival was analyzed.

Results

SOX4 was expressed in 75.0% (102/136) of PGC but not in the normal epithelium of the gallbladder. In addition, the over-expression of SOX4 was significantly associated with low histologic grade (P = 0.02), low pathologic T stage (P = 0.02), and early clinical stage (P = 0.03). The levels of SOX4 immunostainings in PGC tissues with positive nodal metastasis were also significantly lower than those without (P = 0.01). Moreover, Kaplan-Meier curves showed that SOX4 over-expression was significantly related to better overall (P = 0.008) and disease-free survival (P = 0.01). Furthermore, multivariate analyses showed that SOX4 expression was an independent risk factor for both overall (P = 0.03, hazard ratio, 3.682) and disease-free survival (P = 0.04, hazard ratio, 2.215).

Conclusion

Our data indicate for the first time that the over-expression of SOX4 in PGC was significantly correlated with favorable clinicopathologic features and was an independent prognostic factor for better overall and disease-free survival in patients. Therefore, SOX4 might be an auxiliary parameter for predicting malignant behavior for PGC.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1534825818694957.