The tumor suppressor LKB1 antagonizes WNT signaling pathway through modulating GSK3β activity in cell growth of esophageal carcinoma

Multiplexed genome editing by in vivo electroporation of Cas9 ribonucleoproteins effectively induces endometrial carcinoma in mice

Synergistic effects among multiple gene mutations are involved in cancer development and progression. However, developing genetically modified mouse models to analyze various combinations of mutations is extremely labor-intensive and time-consuming. To address these problems, we developed a novel method for in vivo multiplexed genome editing of the murine uterus to model human endometrial carcinoma (EMC). To do this, we injected a CRISPR-Cas9 ribonucleoprotein complex into the uterine cavity of adult female mice, followed by electroporation. Evaluation of reporter mice demonstrated that genome editing occurred specifically in uterine epithelial cells, which are the origin of EMCs. Simultaneous targeting of Pten/Trp53/Lkb1, or targeting of Pten/Lkb1 along with the Ctnnb1ΔEx3 mutation, resulted in efficient generation of invasive tumors in wild-type females within 3 months. This novel method will enable rapid and easy validation of many combinations of gene mutations that lead to endometrial carcinogenesis.

FZD2 regulates cell proliferation and invasion in tongue squamous cell carcinoma

Many studies have shown that FZD2 is significantly associated with tumor development and tumor metastasis. The purpose of the present study was to gain insight into the role of FZD2 in the cell proliferation and invasion of tongue squamous cell carcinoma. According to TCGA-HNSC dataset, among the 10 Frizzled receptors, FZD2 exhibited the highest degree of differential expression between cancer tissues and normal tissues, and the overall survival of patients with higher FZD2 levels was shown to be significantly shorter compared with those with lower FZD2 levels. The upregulation of FZD2 in clinical tongue cancer tissues was validated by real-time PCR. Knockdown of FZD2 inhibited the proliferation, migration and invasion of CAL-27 and TCA-8113 cells, whereas overexpression of FZD2 led to the opposite results. Further analysis revealed that FZD2 is positively correlated with WNT3A, WNT5B, WNT7A and WNT2 and is negatively correlated with WNT4. These results indicated that FZD2 may act as an oncogene in tongue squamous cell carcinoma. Therefore, FZD2 may be a target for the diagnosis, prognosis and gene therapy of tongue cancer.

ALPL regulates the aggressive potential of high grade serous ovarian cancer cells via a non-canonical WNT pathway

The ALPL gene is linked to hypophosphatasia, a rare genetic disease. Owing to the inverse relationships between ALPL expression and both the International Federation of Gynecology and Obstetrics (FIGO) stages and histological grades assigned to patients with serous ovarian cancer (SOC), this study was designed to explore the role and possible mechanisms of ALPL in cell motility of high grade SOC (HGSOC). The effects of ALPL overexpression on migration and invasion were detected in HGSOC cell lines SKOV3 and HEY. Gene ontology analysis for differential genes with ALPL overexpression identified several biological processes, including EMT, correlated with cell motility. Genes potentially implicated in EMT and associated with ALPL were screened using The Cancer Genome Atlas (TCGA) database. The WNT receptor Frizzled2 (FZD2) was identified and its role in HGSOC cell motility and survival was investigated. It was found that forced expression of ALPL could inhibit migration, invasion, and EMT in HGSOC cells. It also reduced the expression of FZD2 and its ligand WNT5A, accompanied by suppressed expression of their downstream target phosphorylated-STAT3 (pSTAT3). These effects were initiated via the FZD2 knockdown using siRNA and reversed by recombinant WNT5A protein. The relationship between FZD2 expression and poor HGSOC patient survival was also investigated. This data supports that ALPL might restrict the function of WNT5A-FZD2-STAT3 axis, a non-canonical WNT pathway for promoting EMT progression, which results in attenuated migration and invasion in HGSOC cells and improves survival in patients with SOC.

Comparative Proteomics of Chromium-Transformed Beas-2B Cells by 2D-DIGE and MALDI-TOF/TOF MS

Chromium (Cr) is a highly toxic, common heavy metal used in industrial production. There are two types of Cr in nature: hexavalent chromium (Cr(VI)) and chromium trichloride (Cr(III)). Cr(III) is involved in the metabolism of sugars and lipids, whereas Cr(VI) is absorbed through the respiratory tract and skin and generates free radicals that result in secondary toxicity. Cr(VI) leads to cancer in the occupational population and is therefore recognized as a human carcinogen by the International Agency for Research on Cancer. The specific mechanism underlying Cr-induced carcinogenesis is complex. In this study, two-dimensional fluorescence difference gel electrophoresis and matrix-assisted laser desorption ionization-time-of-flight/time-of-flight mass spectrometry-based techniques were performed to analyze differentially expressed proteins between Beas-2B human bronchial epithelial cells and Cr(VI)-transformed Beas-2B cells. Many differentially expressed proteins were identified in the cells after malignant transformation, including serine/threonine kinase 11, endothelial nitric oxide synthase 3, apolipoprotein A1, vinculin, and lamin A/C. These proteins are involved in many signaling and metabolic pathways, including apoptosis, autophagy, the PI3K/Akt signaling pathway, focal adhesion, cell motility, and actin cytoskeleton rearrangement.

Transcription factor-7-like 2 (TCF7L2) gene acts downstream of the Lkb1/Stk11 kinase to control mTOR signaling, β cell growth, and insulin secretion

Variants in the transcription factor-7–like 2 (TCF7L2/TCF4) gene, involved in Wnt signaling, are associated with type 2 diabetes. Loss of Tcf7l2 selectively from the β cell in mice has previously been shown to cause glucose intolerance and to lower β cell mass. Deletion of the tumor suppressor liver kinase B1 (LKB1/STK11) leads to β cell hyperplasia and enhanced glucose-stimulated insulin secretion, providing a convenient genetic model for increased β cell growth and function. The aim of this study was to explore the possibility that Tcf7l2 may be required for the effects of Lkb1 deletion on insulin secretion in the mouse β cell. Mice bearing floxed Lkb1 and/or Tcf7l2 alleles were bred with knockin mice bearing Cre recombinase inserted at the Ins1 locus (Ins1Cre), allowing highly β cell–selective deletion of either or both genes. Oral glucose tolerance was unchanged by the further deletion of a single Tcf7l2 allele in these cells. By contrast, mice lacking both Tcf7l2 alleles on this background showed improved oral glucose tolerance and insulin secretion in vivo and in vitro compared with mice lacking a single Tcf7l2 allele. Biallelic Tcf7l2 deletion also enhanced β cell proliferation, increased β cell mass, and caused changes in polarity as revealed by the “rosette-like” arrangement of β cells. Tcf7l2 deletion also increased signaling by mammalian target of rapamycin (mTOR), augmenting phospho-ribosomal S6 levels. We identified a novel signaling mechanism through which a modifier gene, Tcf7l2, lies on a pathway through which LKB1 acts in the β cell to restrict insulin secretion.

miR-632 Promotes Laryngeal Carcinoma Cell Proliferation, Migration, and Invasion Through Negative Regulation of GSK3β

Laryngeal cancer, one of the most common head and neck malignancies, is an aggressive neoplasm. Increasing evidence has demonstrated that microRNAs (miRNAs) exert important roles in oncogenesis and progression of diverse types of human cancers. miR-632, a tumor-related miRNA, has been reported to be dysregulated and implicated in human malignancies; however, its biological role in laryngeal carcinoma remains to be elucidated. The present study aimed at exploring the role of miR-632 in laryngeal cancer and clarifying the potential molecular mechanisms involved. In the current study, miR-632 was found to be significantly upregulated both in laryngeal cancer tissues and laryngeal cancer cell lines. Functional studies demonstrated that miR-632 accelerated cell proliferation and colony formation, facilitated cell migration and invasion, and enhanced the expression of cell proliferation-associated proteins, cyclin D1 and c-myc. Notably, miR-632 could directly bind to the 3′-untranslated region (3′-UTR) of glycogen synthase kinase 3β (GSK3β) to suppress its expression in laryngeal cancer cells. Mechanical studies revealed that miR-632 promoted laryngeal cancer cell proliferation, migration, and invasion through negative modulation of GSK3β. Pearson’s correlation analysis revealed that miR-632 expression was inversely correlated with GSK3β mRNA expression in laryngeal cancer tissues. Taken together, our findings suggest that miR-632 functions as an oncogene in laryngeal cancer and may be used as a novel therapeutic target for laryngeal cancer.

LKB1 inactivation occurs in a subset of esophageal adenocarcinomas and is sufficient to drive tumor cell proliferation

BACKGROUND

The incidence of esophageal adenocarcinoma (EAC) has increased over the last several decades. Apart from mutations in TP53 gene, there are little data on genetic drivers of EAC. Liver kinase B1 (LKB1) has emerged as a multifunctional tumor suppressor regulating cell growth, differentiation, and metabolism. Somatic inactivation of LKB1 has been described in several tumor types; however, whether LKB1 inactivation has a role in EAC is unknown. Here we analyzed patient tumors to assess the prevalence of LKB1 loss in EAC.

METHODS

Chromosomal deletion and expression of LKB1 in EAC were investigated using publicly available genomic data. Protein expression was assessed by immunohistochemistry (IHC) analysis for LKB1 in a tissue microarray (TMA) containing esophageal tumor specimens, including EAC. LKB1 was suppressed in EAC cells to determine the effects on cell growth in vitro.

RESULTS

Analysis of EAC data in The Cancer Genome Atlas dataset revealed significant deletion of chromosome 19p13.3, containing the LKB1 gene locus. Single copy loss (shallow deletion) of LKB1 was present in 58% of EAC samples. Expression of LKB1 was significantly lower in EAC tumors compared with normal esophagus. IHC analysis showed reduced LKB1 protein expression in EAC. Suppression of LKB1 was sufficient to enhance EAC cell growth in vitro.

CONCLUSIONS

Our data suggest that inactivation of LKB1 frequently occurs in EAC. Based on the reported oncogenic effects of LKB1 inactivation, our data indicate that LKB1 loss may play a significant role in EAC tumorigenesis, and point to the need for future studies.

Atypical regulators of Wnt/β-catenin signaling as potential therapeutic targets in Hepatocellular Carcinoma

Hepatocellular carcinoma is one of the most common causes of cancer-related death worldwide. Hepatocellular carcinoma development depends on the inhibition and activation of multiple vital pathways, including the Wnt signaling pathway. The Wnt/β-catenin pathway lies at the center of various signaling pathways that regulate embryonic development, tissue homeostasis and cancers. Activation of the Wnt/β-catenin pathway has been observed frequently in hepatocellular carcinoma. However, activating mutations in β-catenin, Axin and Adenomatous Polyposis Coli only contribute to a portion of the Wnt signaling hyper-activation observed in hepatocellular carcinoma. Therefore, besides mutations in the canonical Wnt components, there must be additional atypical regulation or regulators during Wnt signaling activation that promote liver carcinogenesis. In this mini-review, we have tried to summarize some of these well-established factors and to highlight some recently identified novel factors in the Wnt/β-catenin signaling pathway in hepatocellular carcinoma. Impact statement Early recurrence of human hepatocellular carcinoma (HCC) is a frequent cause of poor survival after potentially curative liver resection. Among the deregulated signaling cascades in HCC, evidence indicates that alterations in the Wnt/β-catenin signaling pathway play key roles in hepatocarcinogenesis. In this review, we summarize the potential molecular mechanisms how the microtubule-associated Protein regulator of cytokinesis 1 (PRC1), a direct Wnt signaling target previously identified in our laboratory to be up-regulated in HCC, in promoting cancer proliferation, stemness, metastasis and tumorigenesis through a complex regulatory circuitry of Wnt3a activities.

Specific deletion of LKB1/Stk11 in the Müllerian duct mesenchyme drives hyperplasia of the periurethral stroma and tumorigenesis in male mice

Nearly all older men will experience lower urinary tract symptoms associated with benign prostatic hyperplasia (BPH), the etiology of which is not well understood. We have generated Stk11^CKO mice by conditional deletion of the liver kinase B1 (LKB1) tumor suppressor gene, Stk11 (serine threonine kinase 11), in the fetal Müllerian duct mesenchyme (MDM), the caudal remnant of which is thought to be assimilated by the urogenital sinus primordial mesenchyme in males during fetal development. We show that MDM cells contribute to the postnatal stromal cells at the dorsal aspect of the prostatic urethra by lineage tracing. The Stk11^CKO mice develop prostatic hyperplasia with bladder outlet obstruction, most likely because of stromal expansion. The stromal areas from prostates of Stk11^CKO mice, with or without significant expansion, were estrogen receptor positive, which is consistent with both MD mesenchyme-derived cells and the purported importance of estrogen receptors in BPH development and/or progression. In some cases, stromal hyperplasia was admixed with epithelial metaplasia, sometimes with keratin pearls, consistent with squamous cell carcinomas. Mice with conditional deletion of both Stk11 and Pten developed similar features as the Stk11^CKO mice, but at a highly accelerated rate, often within the first few months after birth. Western blot analyses showed that the loss of LKB1 and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) induces activation of the phospho-5' adenosine monophosphate-activated protein kinase and phospho-AKT serine/threonine kinase 1 signaling pathways, as well as increased total and active β-catenin. These results suggest that activation of these signaling pathways can induce hyperplasia of the MD stroma, which could play a significant role in the etiology of human BPH.

Notch and Wnt signaling pathway in cancer: Crucial role and potential therapeutic targets (Review)

There is no radical cure for all cancer types. The most frequently used therapies are surgical treatment, radiotherapy and chemotherapy. However, recrudescence, radiation resistance and chemotherapy resistance are the most challenging issues in clinical practice. To address these issues, they should be further studied at the molecular level, and the signaling pathways involved represent a promising avenue for this research. In the present review, we mainly discuss the components and mechanisms of activation of the Notch and Wnt signaling pathways, and we summarize the recent research efforts on these two pathways in different cancers. We also evaluate the ideal drugs that could target these two signaling pathways for cancer therapy, summarize alterations in the Notch and Wnt signaling pathways in cancer, and discuss potential signaling inhibitors as effective drugs for cancer therapy.

Overexpression of Rab5a promotes hepatocellular carcinoma cell proliferation and invasion via FAK signaling pathway

Rab5a was reported to be overexpressed in human malignancy and associated with the malignant phenotype. To data, its expression pattern and biological function in hepatocellular carcinoma (HCC) have not been studied. We analyzed Rab5a protein expression in 98 cases of HCC tissues and four HCC cell lines. We found that Rab5a expression was upregulated in HCC tissues and cell lines. Rab5a overexpression correlated with TNM stage and nodal metastasis (p < 0.05). To confirm the biological function of Rab5a in HCC cell lines, Rab5a siRNA was employed in SK-Hep-1 cell line and plasmid transfection was performed in Huh7 cell line. CCK-8 assay showed that Rab5a depletion blocked cell growth rate while Rab5a overexpression facilitated proliferation. Transwell and migration assay showed that Rab5a positively regulated cell invasion and migration. To explore the molecular mechanism underlying the biological effects of Rab5a, we checked several signaling pathways and found that Rab5a overexpression upregulated cyclin D1, cyclin E expression, FAK (Tyr397), and AKT (Ser473) phosphorylation. Blockage of FAK using inhibitor PF573228 abolished the role of Rab5a on cyclin D1. In conclusion, Rab5a is overexpressed in human HCC and contributes to cancer cell proliferation and invasion through regulation of FAK and AKT signaling.

Genes Regulating Epithelial Polarity Are Critical Suppressors of Esophageal Oncogenesis

Esophageal cancer is an aggressive disease featured by early lymphatic and hematogenous dissemination, and is the sixth leading cause of cancer-related deaths worldwide. The proper formation of apicobasal polarity is essential for normal epithelium physiology and tissue homeostasis, while loss of polarity is a hallmark of cancer development including esophageal oncogenesis. In this review, we summarized the stages of esophageal cancer development associated with the loss or deregulation of epithelial cell apicobasal polarity. Loss of epithelial apicobasal polarity exerts an indispensable role in the initiation of esophageal oncogenesis, tumor progression, and the advancement of tumors from benign to malignant. In particular, we reviewed the involvement of several critical genes, including Lkb1, claudin-4, claudin-7, Par3, Lgl1, E-cadherin, and the Scnn1 gene family. Understanding the role of apicobasal regulators may lead to new paradigms for treatment of esophageal tumors, including improvement of prognostication, early diagnosis, and individually tailored therapeutic interventions in esophageal oncology.

Single nucleotide polymorphisms in CRTC1 and BARX1 are associated with esophageal adenocarcinoma

Objective:

Recently, single nucleotide polymorphisms (SNPs) associated with esophageal adenocarcinoma (EAC) and Barrett's esophagus (BE) were identified; rs10419226 (CRTC1), rs11789015 (BARX1), rs2687201 (FOXP1), rs2178146 (FOXF1), rs3111601 (FOXF1), and rs9936833 (FOXF1). These findings indicate that genetic susceptibility could play a role in the initiation of EAC in BE patients. The aim of this study was to validate the association between these previously identified SNPs and the risk of EAC in an independent and large case–control study.

Design:

Six SNPs found to be associated with EAC and BE were genotyped by a multiplex SNaPshot analysis in 1071 EAC patients diagnosed and treated in the Netherlands. Allele frequencies were compared to a control group derived from the Rotterdam Study, a population-based prospective cohort study (n = 6206). Logistic regression analysis and meta-analysis were performed to calculate odds ratios (OR).

Results:

Rs10419226 (CRTC1) showed a significantly increased EAC risk for the minor allele (OR = 1.17, P = 0.001), and rs11789015 (BARX1) showed a significantly decreased risk for the minor allele (OR = 0.85, P = 0.004) in the logistic regression analysis. The meta-analysis of the original GWAS and the current study revealed an improved level of significance for rs10419226 (CRTC1) (OR = 1.18, P = 6.66 × 10^–10) and rs11789015 (BARX1) (OR = 0.83, P = 1.13 × 10^–8).

Conclusions:

This independent and large Dutch case–control study confirms the association of rs10419226 (CRTC1) and rs11789015 (BARX1) with the risk of EAC. These findings suggest a contribution of the patient genetic make-up to the development of EAC and might contribute to gain more insight in the etiology of this cancer.

A functional SNP in the MDM2 promoter mediates E2F1 affinity to modulate cyclin D1 expression in tumor cell proliferation

BACKGROUND

The MDM2 oncogene, a negative regulator of p53, has a functional polymorphism in the promoter region (SNP309) that is associated with multiple kinds of cancers including non-melanoma skin cancer. SNP309 has been shown to associate with accelerated tumor formation by increasing the affinity of the transcriptional activator Sp1. It remains unknown whether there are other factors involved in the regulation of MDM2 transcription through a trans-regulatory mechanism.

METHODS

In this study, SNP309 was verified to be associated with overexpression of MDM2 in tumor cells. Bioinformatics predicts that the T to G substitution at SNP309 generates a stronger E2F1 binding site, which was confirmed by ChIP and luciferase assays.

RESULTS

E2F1 knockdown downregulates the expression of MDM2, which confirms that E2F1 is a functional upstream regulator. Furthermore, tumor cells with the GG genotype exhibited a higher proliferation rate than TT, correlating with cyclin D1 expression. E2F1 depletion significantly inhibits the proliferation capacity and downregulates cyclin D1 expression, especially in GG genotype skin fibroblasts. Notably, E2F1 siRNA effects could be rescued by cyclin D1 overexpression.

CONCLUSION

Taken together, a novel modulator E2F1 was identified as regulating MDM2 expression dependent on SNP309 and further mediates cyclin D1 expression and tumor cell proliferation. E2F1 might act as an important factor for SNP309 serving as a rate-limiting event in carcinogenesis.

Overexpression of SPAG9 correlates with poor prognosis and tumor progression in hepatocellular carcinoma

Sperm-associated antigen 9 (SPAG9) was reported as a novel biomarker for several cancers and associated with the malignant behavior of cancer cells. However, its expression pattern and biological role in human hepatocellular carcinoma (HCC) have not been reported. In the present study, we analyzed SPAG9 expression in human HCC tissues by immunohistochemistry and found that SPAG9 overexpression is correlated with tumor stage (p < 0.001), tumor multiplicity (p = 0.019), tumor size (p = 0.034), AFP levels (p = 0.006), and tumor relapse (p = 0.0017). Furthermore, SPAG9 overexpression is correlated with poor overall survival (p < 0.001) and relapse-free survival (p = 0.002). Transfection of SPAG9 small interfering RNA (siRNA) was performed in Bel-7402 cell line. Colony formation and MTT showed that SPAG9 siRNA knockdown inhibited HCC cell proliferation. We also found that SPAG9 depletion could increase cell apoptosis. In addition, the level of cyclin D1 and cyclin E protein expression was downregulated after siRNA treatment. In conclusion, SPAG9 is overexpressed in human HCC and serves as a prognostic marker. SPAG9 contributes to cancer cell growth through regulation of cyclin proteins.

Rewiring cell polarity signaling in cancer

Disrupted cell polarity is a feature of epithelial cancers. The Crumbs, Par and Scribble polarity complexes function to specify and maintain apical and basolateral membrane domains, which are essential to organize intracellular signaling pathways that maintain epithelial homeostasis. Disruption of apical-basal polarity proteins facilitates rewiring of oncogene and tumor suppressor signaling pathways to deregulate proliferation, apoptosis, invasion and metastasis. Moreover, apical-basal polarity integrates intracellular signaling with the microenvironment by regulating metabolic signaling, extracellular matrix remodeling and tissue level organization. In this review, we discuss recent advances in our understanding of how polarity proteins regulate diverse signaling pathways throughout cancer progression from initiation to metastasis.