Aberrant expression of SOX2 upregulates MUC5AC gastric foveolar mucin in mucinous cancers of the colorectum and related lesions

The SOX2 response program in glioblastoma multiforme: an integrated ChIP-seq, expression microarray, and microRNA analysis

Background

SOX2 is a key gene implicated in maintaining the stemness of embryonic and adult stem cells. SOX2 appears to re-activate in several human cancers including glioblastoma multiforme (GBM), however, the detailed response program of SOX2 in GBM has not yet been defined.

Results

We show that knockdown of the SOX2 gene in LN229 GBM cells reduces cell proliferation and colony formation. We then comprehensively characterize the SOX2 response program by an integrated analysis using several advanced genomic technologies including ChIP-seq, microarray profiling, and microRNA sequencing. Using ChIP-seq technology, we identified 4883 SOX2 binding regions in the GBM cancer genome. SOX2 binding regions contain the consensus sequence wwTGnwTw that occurred 3931 instances in 2312 SOX2 binding regions. Microarray analysis identified 489 genes whose expression altered in response to SOX2 knockdown. Interesting findings include that SOX2 regulates the expression of SOX family proteins SOX1 and SOX18, and that SOX2 down regulates BEX1 (brain expressed X-linked 1) and BEX2 (brain expressed X-linked 2), two genes with tumor suppressor activity in GBM. Using next generation sequencing, we identified 105 precursor microRNAs (corresponding to 95 mature miRNAs) regulated by SOX2, including down regulation of miR-143, -145, -253-5p and miR-452. We also show that miR-145 and SOX2 form a double negative feedback loop in GBM cells, potentially creating a bistable system in GBM cells.

Conclusions

We present an integrated dataset of ChIP-seq, expression microarrays and microRNA sequencing representing the SOX2 response program in LN229 GBM cells. The insights gained from our integrated analysis further our understanding of the potential actions of SOX2 in carcinogenesis and serves as a useful resource for the research community.

GLI1 facilitates the migration and invasion of pancreatic cancer cells through MUC5AC-mediated attenuation of E-cadherin

The Krüppel-like zinc-finger protein GLI1 functions as a downstream transcription factor of Hedgehog signaling and plays a pivotal role in the cellular proliferation of many types of tumors, including pancreatic ductal adenocarcinoma (PDA). PDA develops from dysplastic lesions called pancreatic intraepithelial neoplasia (PanIN) through a multistep carcinogenesis process that changes its cellular characteristics, including a mucin expression profile. Increased expression of a gel-forming mucin, MUC5AC, was previously revealed as a major biomarker for the poor prognosis of PDA patients, but the molecular mechanisms responsible for its expression and correlation with poor prognosis are not fully understood. Here we show that MUC5AC is a direct transcriptional target of GLI1 in PDA cells. Overexpression of GLI1 enhanced MUC5AC expression, and a double knockdown of GLI1 and GLI2 suppressed endogenous MUC5AC expression in PDA cells. Luciferase reporter assays revealed that GLI1 and GLI2 can activate the MUC5AC promoter through its conserved CACCC-box-like cis-regulatory elements. We also found that GLI1-upregulated MUC5AC was expressed in the intercellular junction between cultured PDA cells and interfered with the membrane localization of E-cadherin, leading to decreased E-cadherin-dependent cell-cell adhesion and promoting the migration and invasion of PDA cells. Consistently, GLI1 induced the nuclear accumulation and target gene expression of β-catenin in a MUC5AC-dependent manner. Finally, immunohistochemical analysis revealed that GLI1 expression statistically correlated with MUC5AC expression and also with altered subcellular localization of E-cadherin and β-catenin in PanIN lesions and PDA. This evidence revealed a new aspect of GLI1 function in modulating E-cadherin/β-catenin-regulated cancer cell properties through the expression of a gel-forming mucin.

Immunohistochemical analysis of colorectal cancer with gastric phenotype: claudin-18 is associated with poor prognosis

Claudin-18 plays a key role in constructing tight junctions, and altered claudin-18 expression has been documented in various human malignancies; however, little is known about the biological significance of claudin-18 in colorectal cancer (CRC). The aim of this study is to investigate the significance of claudin-18 expression in CRC and its association with clinicopathological factors. We performed clinicopathological analysis of claudin-18 expression in a total of 569 CRCs by immunohistochemistry. Moreover, we investigated the association between claudin-18 and various markers including gastric/intestinal phenotype (MUC5AC, MUC6, MUC2 and CD10), CDX2, claudin-3, claudin-4, p53 and Ki-67. Claudin-18 expression was detected in 21 of the 569 CRCs (4%) and was seen exclusively on the cell membrane. Positive expression of claudin-18 showed a significant correlation with positive expression of MUC5AC (P < 0.0001) and negative expression of CDX2 (P= 0.0013). The prognosis of patients with positive claudin-18 expression was significantly poorer than in negative cases (P= 0.0106). Multivariate analysis revealed that T grade, M grade and claudin-18 expression were independent predictors of survival in patients with CRC. We revealed that claudin-18 expression correlates with poor survival in patients with CRC and is associated with the gastric phenotype.

Expression of Sox2 in human cervical carcinogenesis

Sox2 is a key transcription factor for embryonic development and plays a critical role in determining the fate of stem cells. Recently, Sox2 has been detected in several human tumors, indicating a potential function in tumorigenesis. We initially reported remarkably increased nuclear Sox2 staining in cervical carcinomas compared with normal cervix (P < .05). Furthermore, Sox2 staining was detected in most tumorsphere cells isolated from fresh cervical cancer tissues but not among the differentiated tumorsphere cells. When Sox2 was stably expressed in cervical cancer cells (SiHa and HeLa), Sox2-overexpressing cells had increased proliferation, clonogenicity, and tumorigenicity in vitro and in vivo than control cells. These results suggest that Sox2 may participate in carcinogenesis of cervical carcinomas and may be a potential therapeutic target molecule for cervical cancers.

SOX2 in gastric carcinoma, but not Hath1, is related to patients' clinicopathological features and prognosis

BACKGROUND

SOX2 and Hath1 are transcription factors that are critical for the control of terminal cell differentiation in the gastrointestinal mucosa. This study investigated the correlations between SOX2 and Hath1 expression in gastric carcinoma and patients' clinicopathological features and prognosis.

METHODS

Hath1 and SOX2 were detected by immunohistochemistry in gastric carcinoma (n = 50). Probability of survival of patients after surgery was estimated by the Kaplan-Meier method and compared using Log-rank test.

RESULTS

Hath1 and SOX2 were inversely expressed in gastric carcinoma. Patients with strong SOX2 expression (++ to +++) showed lower incidences of lymph node metastasis (p = 0.007), deeper invasion (p = 0.010), and III-IV clinical stages (p = 0.011) compared to patients with low SOX2 expression (- to +). There was no significant difference in SOX2 and Hath1 expression in the cancerous tissues of the patients with and without Helicobacter pylori infection (p > 0.05). The patients with strong expression of SOX2 in their cancerous tissues (++ to +++) had a better prognosis than those with low expression of SOX2 (- to +; p = 0.005). There was no correlation between Hath1 expression level and prognosis (p = 0.676).

CONCLUSIONS

SOX2 and Hath1 are inversely expressed in gastric carcinoma. SOX2 provides a survival advantage to patients of gastric carcinoma and appears to be associated with metastasis and clinical stages.

Expression of Sox2 in human ovarian epithelial carcinoma

OBJECTIVES

The aim of this study was to investigate the expression of Sox2, a transcription factor, in a series of benign, borderline, and malignant ovarian tumors and to evaluate whether Sox2 expression levels correlate with clinicopathological characteristics in ovarian epithelial carcinoma.

METHODS

This study investigated immunohistochemical expressions of Sox2 in 43 species of normal ovarian epithelia, 284 species of serous epithelial lesions, and 164 species of mucinous epithelial lesions to assess their clinicopathological relevance.

RESULTS

Immunohistochemical results showed that the positive ratio of Sox2 expression gradually increased from benign and borderline to malignant ovarian tumors; 55.81% of normal ovarian epithelia, ~65% of serous and mucinous cystadenoma, ~70% of borderline serous and mucinous cystadenoma, and ~91% of serous and mucinous cystadenocarcinoma expressed Sox2, respectively. However, there was no significant correlation between Sox2 expression and the age and level of CA125 in patients with either serous or mucinous tumors. Positive correlations between Sox2 expression levels and FIGO stage or pathological stage were identified in both serous and mucinous cystadenocarcinoma samples.

CONCLUSION

The expression level of Sox2 in human ovarian tumors was directly proportional to their degree of malignancy, implying that Sox2 overexpression may be closely related to the malignant transformation of ovarian tumors.

Sox2 is required for maintenance and differentiation of bronchiolar Clara, ciliated, and goblet cells

The bronchioles of the murine lung are lined by a simple columnar epithelium composed of ciliated, Clara, and goblet cells that together mediate barrier function, mucociliary clearance and innate host defense, vital for pulmonary homeostasis. In the present work, we demonstrate that expression of Sox2 in Clara cells is required for the differentiation of ciliated, Clara, and goblet cells that line the bronchioles of the postnatal lung. The gene was selectively deleted in Clara cells utilizing Scgb1a1-Cre, causing the progressive loss of Sox2 in the bronchioles during perinatal and postnatal development. The rate of bronchiolar cell proliferation was decreased and associated with the formation of an undifferentiated, cuboidal-squamous epithelium lacking the expression of markers of Clara cells (Scgb1a1), ciliated cells (FoxJ1 and α-tubulin), and goblet cells (Spdef and Muc5AC). By adulthood, bronchiolar cell numbers were decreased and Sox2 was absent in extensive regions of the bronchiolar epithelium, at which time residual Sox2 expression was primarily restricted to selective niches of CGRP staining neuroepithelial cells. Allergen-induced goblet cell differentiation and mucus production was absent in the respiratory epithelium lacking Sox2. In vitro, Sox2 activated promoter-luciferase reporter constructs for differentiation markers characteristic of Clara, ciliated, and goblet cells, Scgb1a1, FoxJ1, and Agr2, respectively. Sox2 physically interacted with Smad3 and inhibited TGF-β1/Smad3-mediated transcriptional activity in vitro, a pathway that negatively regulates proliferation. Sox2 is required for proliferation and differentiation of Clara cells that serve as the progenitor cells from which Clara, ciliated, and goblet cells are derived.

Tumors originating from induced pluripotent stem cells and methods for their prevention

Pluripotent stem cells represent an almost unlimited source of most somatic cell types, providing them with great potential for cell-based therapies. The earliest methods used for generating human pluripotent stem cells as embryonic stem cells from human embryos suffered from ethical and technical drawbacks. These problems have been solved in part through the efficient induction of pluripotency in somatic cells using forced expression of a tetrad of factors. Here, we describe the formation of rhabdomyosarcomas originating from factor-induced pluripotent stem (iPS) cells derived from mouse neural stem cells. This underscores the commonly accepted notion that the use of retroviral delivery methods for inducing pluripotency will not be suited for clinical applications. However, the iPS cell field is developing rapidly. Safer protocols are now available for producing pluripotent stem cells. Here the current state-of-the-art in this field will be discussed.

SOX2 is highly expressed in squamous cell carcinomas of the gastrointestinal tract

SOX2 is a high-mobility group box embryonic stem cell transcription factor that is expressed in the developing foregut and normal gastric epithelium and is downregulated in intestinal metaplasia of the stomach and esophagus. In addition, SOX2 colocalizes with p63 in the basal layer and plays a critical role in the maintenance of the stratified squamous epithelium of the esophagus. SOX2 expression in squamous cell carcinomas of the gastrointestinal tract has not been previously evaluated. The purpose of this study was to determine whether SOX2 is differentially expressed in squamous cell carcinomas versus adenocarcinomas of the esophagus and rectum/anal canal and to compare its expression to p63, cytokeratin 5/6, and CDX2. In total, 93 tumors were evaluated: 26 esophageal squamous cell carcinomas, 23 esophageal adenocarcinomas, 21 squamous cell carcinomas of the anal canal, and 23 rectal adenocarcinomas. SOX2 was expressed in 81% of esophageal squamous cell carcinomas and 91% of anal canal squamous cell carcinomas, compared to 13% and 17% of esophageal and rectal adenocarcinomas, respectively. p63 was expressed in 96% of esophageal squamous cell carcinomas and 100% of anal canal squamous cell carcinomas; the single squamous cell carcinoma negative for p63 was strongly positive for SOX2. Cytokeratin 5/6 was expressed in most esophageal and anal canal squamous cell carcinomas, but was also positive in 43% of esophageal adenocarcinomas and 13% of rectal adenocarcinomas. In summary, SOX2 is preferentially expressed in squamous cell carcinomas of the esophagus and anal canal compared to adenocarcinomas from these sites. SOX2 may be useful in an immunohistochemical panel to differentiate between squamous cell carcinomas and adenocarcinomas of the gastrointestinal tract.

Comprehensive analysis of the clinical significance of inducing pluripotent stemness-related gene expression in colorectal cancer cells

BACKGROUND

We previously determined that cancer stem-like cells may influence the susceptibility of colorectal cancer (CRC) cells to chemotherapeutic agents. Although Takahashi and Park identified a set of induced pluripotent stem cell (iPS)-related genes required for normal stem cell maintenance, the precise role of iPS-related gene expression in CRC pathogenesis remains to be determined. The purpose of this study was to clarify the clinical relevance of "stemness"-regulating gene expression in CRC cases.

MATERIALS AND METHODS

Cancer cells were excised from tissues of 79 CRC cases by laser microdissection (LMD), and quantitative RT-PCR was used to evaluate expression levels of the iPS-related genes c-MYC, SOX2, OCT3/4, LIN28, KLF4, and NANOG, and to identify any associations between their expression and clinicopathological CRC progression.

RESULTS

We found that LIN28 expression is significantly associated with lymph node metastasis (p = 0.018) and Dukes stage (p = 0.0319). SOX2expression is also correlated with lymph node metastasis. Furthermore, the ten cases with Dukes D disease expressed significantly higher levels of SOX2transcript than the other 69 cases (p = 0.0136). In contrast, KLF4 expression was inversely related to Dukes stage. Expression of c-MYC, OCT3/4, and NANOG did not appear to have clinical relevance in CRC cases.

CONCLUSION

The present analysis strongly suggests that altered expression of several iPS-related genes plays a role in CRC pathogenesis.

Stimulatory role of PKCalpha in extracellular regulated kinase 1/2 pathway in conjunctival goblet cell proliferation

PURPOSE

To determine whether a constitutively active protein kinase C (PKC)-alpha stimulates rat and human conjunctival goblet cell proliferation through activation of ERK 1/2.

METHODS

Conjunctivas from rat and human were minced and goblet cells were allowed to grow. Goblet cells were serum starved and incubated with an adenovirus containing a constitutively active form of PKCalpha (Ad-myr-PKCalpha, 1 x 10(7) pfu), EGF (10(-7) M), or both. The location of myrPKCalpha was determined by immunofluorescence microscopy. Cultured goblet cells were preincubated with the PKC inhibitor calphostin C (10(-10)-10(-7) M) or the ERK 1/2 inhibitor U0126 (10(-9)-10(-6) M) before incubation with Ad-myr-PKCalpha. Cell proliferation was measured.

RESULTS

Transduction of rat goblet cells with Ad-myr-PKCalpha did not change PKC location compared with nontransduced cells. Incubation with Ad-myr-PKCalpha caused an increase in cell proliferation by 2.5+/-0.3-fold, whereas EGF increased proliferation by 2.1+/-0.2-fold. Simultaneous addition of Ad-myr-PKCalpha and EGF did not further increase proliferation. U0126 inhibited Ad-myr-PKCalpha-stimulated proliferation a maximum of 70%. In human goblet cells, incubation with Ad-myr-PKCalpha caused an increase in cell proliferation by 2.3+/-0.3-fold, whereas EGF increased proliferation by 3.1+/-0.4-fold. Simultaneous addition of Ad-myr-PKCalpha and EGF decreased proliferation compared with either compound alone. Ad-myr-PKCalpha caused ERK 1/2 to translocate to the nucleus in rat and human cells, but the translocation was blocked by U0126.

CONCLUSIONS

Activation of PKCalpha alone by inducing phosphorylation of ERK 1/2 and translocating it to the nucleus is necessary and sufficient to cause conjunctival cell proliferation in rat, and probably human, goblet cells.