Slug inhibits the proliferation and tumor formation of human cervical cancer cells by up-regulating the p21/p27 proteins and down-regulating the activity of the Wnt/β-catenin signaling pathway via the trans-suppression Akt1/p-Akt1 expression

Mechanistic insights into the impact of WIN 55, 212-2, a synthetic cannabinoid, on adhesion molecules PECAM-1 and VE-cadherin in HeLa cells: implications on cancer processes

The endocannabinoid (eCB) system comprises endogenous ligands, cannabinoid receptors (CBRs), and their regulatory proteins; its alteration leads to many diseases including cancer. Thus, becomes a therapeutic target for synthetic cannabinoids aimed to control cancer cell proliferation, migration, adhesion, and invasion. However, little is known about adhesion molecules regulation through CBRs activation. The aim of this study was to evaluate the effects of a CB1/CB2 agonist, WIN-55, 212-2 (WIN), on the regulation of adhesion molecules platelet endothelial cell adhesion molecule-1 (PECAM-1) and vascular endothelial cadherin (VE-cadherin) in HeLa cells. CBRs expression was evaluated by immunofluorescence staining in HeLa cells and cell viability (thiazolyl blue tetrazolium bromide), cell adhesion (crystal violet), adhesion molecules expression and location (Western blot and immunofluorescence staining assays) were all assessed on cells treated with different WIN concentrations. Receptors CB1, CB2, and G-protein-coupled receptor 55 were expressed in HeLa cells. Additionally, biphasic effects were observed in their metabolic activity and adhesive properties: low WIN concentrations resulted in significant increases whereas, high ones decreased them compared to controls (p < 0.0001), demonstrating that WIN elicits opposite effects depending on the concentration and exposure time. PECAM-1 was detected in HeLa cell's cytoplasm, membrane, and perinuclear region, whereas VE-cadherin had a nuclear distribution. There were no significant differences in PECAM-1 and VE-cadherin expression and location, suggesting that WIN does not modulate these proteins. These findings support the potential use of WIN due to its anticancer properties without dysregulating adhesion molecules. WIN possible contribution to inhibit cancer progression should be further investigated.

SNAI2 enhances HPV‑negative cervical cancer cell dormancy by modulating u‑PAR expression and the activity of the ERK/p38 signaling pathway in vitro

The prognosis of patients with human papillomavirus (HPV)‑negative cervical cancer is significantly worse than that of patients with HPV‑positive cervical cancer. Understanding the mechanisms of this is crucial for preventing disease evolution. In the present study, the GV367‑snail family transcriptional repressor 2 (SNAI2) lentiviral vector was constructed and transduced into C‑33A cells. Subsequently, the proliferation of tumor cells was detected using the Cell Counting Kit (CCK)‑8 method. Flow cytometry was used to analyze the cell cycle progression of tumor cells. The glucose consumption of tumor cells was detected using an oxidase assay, and the senescence of tumor cells was detected using beta‑galactosidase staining. The gene expression and the activity of p38 and ERK1/2 were detected using reverse transcription‑quantitative PCR and western blotting, respectively. The C‑33A‑SNAI2 cell line was successfully established. Compared with HeLa and C‑33A‑Wild cells, the proliferation and percentage of G0/G1‑phase cells in the C‑33A‑SNAI2 group were decreased, as detected by the CCK‑8 assay (100±0 vs. 239.1±58.3 vs. 39.7±20.1, P<0.01) and flow cytometry (34.0±7.1% vs. 46.2±10.6% vs. 61.3±5.3%, P<0.05). Compared with the HeLa group, the glucose consumption of the C‑33A‑Wild and C‑33A‑SNAI2 groups was significantly decreased (P<0.01). The results of beta‑galactosidase staining showed that the proportion of beta‑galactosidase‑positive cells in the C‑33A‑SNAI2 group was significantly decreased compared with the C‑33A‑Wild group (P<0.01). Upregulation of SNAI2 enhanced the increase in p21 expression, and the decrease in CDK1, urokinase plasminogen activator receptor (u‑PAR) and cyclin D1 expression in C‑33A cells compared with C‑33A‑Wild cells (P<0.05). In addition, the activities of p38, ERK1/2 and the phosphorylated (p)‑ERK1/2/p‑p38 ratio were decreased in the C‑33A‑SNAI2 group compared with the C‑33A‑Wild and HeLa groups (P<0.05). In conclusion, SNAI2 enhanced HPV‑negative cervical cancer C‑33A cell dormancy, which was characterized by G0/G1 arrest, by the downregulation of u‑PAR expression, and a decrease in the activity of the p‑ERK1/2 and p‑p38MAPK signaling pathways in vitro. Cancer recurrence and metastases are responsible for most cancer‑related deaths. Given that SNAI2 is required for enhancing HPV‑negative cervical cancer cell dormancy, regulating this process may promote cervical tumor cells to enter a continuous dormant state, which could be a potential approach for tumor therapy.

SNAI2 promotes the malignant transformation of oral leukoplakia by modulating p-EMT

OBJECTIVE

Snail family transcriptional repressor 2 (SNAI2) is a key regulator of partial epithelial-mesenchymal transition (p-EMT) and is associated with tumorigenesis. Whether SNAI2 promotes oral leukoplakia (OLK) malignant transformation by modulating p-EMT is unclear.

MATERIALS AND METHODS

This study utilized two clinical datasets (GSE26549 and GSE85195) from the Gene Expression Omnibus database, cytological experiments, and a 4-nitroquinoline 1-oxide-induced mice model to explore the role of SNAI2 in OLK malignant transformation.

RESULTS

The clinical cohort found SNAI2, as a risk factor (HR = 2.50, 95% CI: 1.08-5.79, p = 0.033), could promote OLK malignant transformation (p = 0.012). Cytological experiments indicated that SNAI2 overexpression promoted DOK cell proliferation, invasion, migration, and increase the protein expression of p-EMT relative signatures, whereas SNAI2 silencing has opposite effects. Furthermore, the mice model and clinical datasets demonstrated the expression of SNAI2 and p-EMT relative signatures were increased with OLK malignant transformation. And SNAI2 was strongly correlated with p-EMT. Besides, co-expressed genes of SNAI2 were also enriched in p-EMT relative biological processes and signaling pathways.

CONCLUSIONS

p-EMT plays a significant role in promoting the OLK malignant transformation. As an important regulator of p-EMT, SNAI2 could be a target to block the OLK malignant transformation.

EMT/MET plasticity in cancer and Go-or-Grow decisions in quiescence: the two sides of the same coin?

Epithelial mesenchymal transition (EMT) and mesenchymal epithelial transition (MET) are genetic determinants of cellular plasticity. These programs operate in physiological (embryonic development, wound healing) and pathological (organ fibrosis, cancer) conditions. In cancer, EMT and MET interfere with various signalling pathways at different levels. This results in gross alterations in the gene expression programs, which affect most, if not all hallmarks of cancer, such as response to proliferative and death-inducing signals, tumorigenicity, and cell stemness. EMT in cancer cells involves large scale reorganisation of the cytoskeleton, loss of epithelial integrity, and gain of mesenchymal traits, such as mesenchymal type of cell migration. In this regard, EMT/MET plasticity is highly relevant to the Go-or-Grow concept, which postulates the dichotomous relationship between cell motility and proliferation. The Go-or-Grow decisions are critically important in the processes in which EMT/MET plasticity takes the central stage, mobilisation of stem cells during wound healing, cancer relapse, and metastasis. Here we outline the maintenance of quiescence in stem cell and metastatic niches, focusing on the implication of EMT/MET regulatory networks in Go-or-Grow switches. In particular, we discuss the analogy between cells residing in hybrid quasi-mesenchymal states and G_Alert, an intermediate phase allowing quiescent stem cells to enter the cell cycle rapidly.

The Immunohistochemical Expression of Epithelial-Mesenchymal Transition Markers in Precancerous Lesions and Cervical Cancer

In the epithelial-mesenchymal transition (EMT) process, cells lose their epithelial phenotype and gain mesenchymal features. This phenomenon was observed in the metastatic phase of neoplastic diseases, e.g., cervical cancer. There are specific markers that are expressed in the EMT. The aim of this study was to determine the localization of and associations between the immunohistochemical (IHC) expression of TWIST, SNAIL, and SLUG proteins in precancerous lesions and cervical cancer. The IHC analysis disclosed higher expressions of EMT markers in precancerous lesions and cervical cancer than in the control group. Moreover, stronger expression of TWIST, SNAIL, and SLUG was observed in cervical intraepithelial neoplasia grade 3 (CIN3) vs. CIN1, CIN3 vs. CIN2, and CIN2 vs. CIN1 cases (p < 0.05). In cervical cancer, IHC reactions demonstrated differences in TWIST, SNAIL, and SLUG expression in grade 1 (G1) vs. grade 2 (G2) (p < 0.0011; p < 0.0017; p < 0.0001, respectively) and in G1 vs. grade 3 (G3) (p < 0.0029; p < 0.0005; p < 0.0001, respectively). The results of our study clearly showed that existing differences in the expression of the tested markers in precancerous vs. cancerous lesions may be utilized in the diagnosis of cervical cancer. Further studies on bigger populations, as well as in comparison with well-known markers, may improve our outcomes.

SNAI2 Attenuated the Stem-like Phenotype by Reducing the Expansion of EPCAMhigh Cells in Cervical Cancer Cells

SNAI2 (Snai2) is a zinc-finger transcriptional repressor that belongs to the Snail family. The accumulated evidence suggests that SNAI2 exhibits biphasic effects on regulating a stem-like phenotype in various types of cells, both normal and malignant. In this study, by exogenously expressing SNAI2 in SiHa cells, SNAI2 exhibited the capacity to inhibit a stem-like phenotype in cervical cancer cells. The SNAI2-overexpressing cells inhibited cell growth, tumorsphere formation, tumor growth, enhanced sensitivity to cisplatin, reduced stem cell-related factors' expression, and lowered tumor initiating frequency. In addition, the EPCAM^high cells sorted from SiHa cells exhibited an enhanced capacity to maintain a stem-like phenotype. Further study demonstrated that the trans-suppression of EPCAM expression by SNAI2 led to blockage of the nuclear translocation of β-catenin, as well as reduction in SOX2 and c-Myc expression in SiHa and HeLa cells, but induction in SNAI2 knockdown cells (CaSki), which would be responsible for the attenuation of the stem-like phenotype in cervical cancer cells mediated by SNAI2. All of these results demonstrated that SNAI2 could attenuate the stem-like phenotype in cervical cancer cells through the EPCAM/β-catenin axis.

Hexokinases 2 promoted cell motility and distant metastasis by elevating fibronectin through Akt1/p-Akt1 in cervical cancer cells

Background

Hexokinases 2 (HK2) is a member of the hexokinases, linking with malignant tumor growth and distant metastasis. However, evidence regarding the potential role of HK2 in regulating cell motility and tumor metastasis during the cervical cancer malignant progression remains limited.

Methods

In vitro migration and invasion assay, in vivo metastasis experiments were performed to detect the effective of HK2 on regulating cell motility and tumor metastasis in cervical cancer cells. RNA-Seq was performed to explore the potential molecules that participate in HK2-mediated cell motility and tumor metastasis in cervical cancer cells. The correlation between HK2 and Akt1, p-Akt1, FN1 expression in cervical cancer cells and human squamous cervical carcinoma (SCC) samples was verified in this study.

Results

In this study, cervical cancer cells with exogenous HK2 expression exhibited enhanced cell motility and distant metastasis. Transcriptome sequencing analysis revealed that fibronectin (FN1) was significantly increased in HK2-overexpressing HeLa cells, and the PI3K/Akt signaling pathway was identified by KEGG pathway enrichment analysis. Further studies demonstrated that this promotion of cell motility by HK2 was probably a result of it inducing FN1, MMP2 and MMP9 expression by activating Akt1 in cervical cancer cells. Additionally, HK2 expression was altered with the changing of Akt1/p-Akt1 expression, implying that HK2 expression is also modulated by Akt1/p-Akt1. Moreover, the positive correlation between HK2 and Akt1, p-Akt1, FN1 expression in human squamous cervical carcinoma (SCC) samples was verified by using Pearson correlation analysis.

Conclusions

This study demonstrated that HK2 could activate Akt1 in cervical cancer cells, subsequently enhancing cell motility and tumor metastasis by inducing FN1, MMP2 and MMP9 expression. There likely exists an interactive regulatory mechanism between HK2 and Akt1 during the malignant process of cervical cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02312-0.

PRDM4 inhibits cell proliferation and tumorigenesis by inactivating the PI3K/AKT signaling pathway through targeting of PTEN in cervical carcinoma

PR domain zinc finger protein 4 (PRDM4) is a transcription factor that plays key roles in stem cell self-renewal and tumorigenesis. However, its biological role and exact mechanism in cervical cancer remain unknown. Here, both immunohistochemistry (IHC) and Western blot assays demonstrated that the expression of PRDM4 in cervical cancer tissues was much lower than that in the normal cervix. A xenograft assay showed that PRDM4 overexpression in the cervical cancer cell lines SiHa and HeLa dramatically inhibited cell proliferation and tumorigenic potential in vivo. Conversely, the silencing of PRDM4 promoted cervical cancer cell proliferation and tumorigenic potential. Mechanistically, PRDM4 induced cell cycle arrest at the transition from G0/G1 phase to S phase by upregulating p27 and p21 expression and downregulating Cyclin D1 and CDK4 expression. Furthermore, the PI3K/AKT signaling pathway was inactivated in PRDM4-overexpressing cells, which decreased the levels of p-AKT and upregulated the expression of PTEN, an inhibitor of the PI3K/AKT signaling pathway, at both the transcriptional and translational levels. Dual-luciferase reporter assays and qChIP assays confirmed that PRDM4 transactivated the expression of PTEN by binding to two specific regions in the PTEN promoter. Furthermore, PTEN silencing or a PTEN inhibitor rescued the cell defects induced by PRDM4 overexpression. Therefore, our data suggest that PRDM4 inhibits cell proliferation and tumorigenesis by downregulating the activity of the PI3K/AKT signaling pathway by directly transactivating PTEN expression in cervical cancer.

Inhibiting the Pkm2/b-catenin axis drives in vivo replication of adult cardiomyocytes following experimental MI

Adult mammalian cardiomyocytes (CM) are postmitotic, differentiated cells that cannot re-enter the cell cycle after any appreciable injury. Therefore, understanding the factors required to induce CM proliferation for repair is of great clinical importance. While expression of muscle pyruvate kinase 2 (Pkm2), a cytosolic enzyme catalyzing the final step in glycolysis, is high in end-stage heart failure (HF), the loss of Pkm2 promotes proliferation in some cellular systems, in vivo. We hypothesized that in the adult heart CM proliferation may require low Pkm2 activity. Thus, we investigated the potential for Pkm2 to regulate CM proliferation in a mouse model of myocardial infarction (MI) employing inducible, cardiac-specific Pkm2 gene knockout (Pkm2KOi) mice. We found a lack of cardiac hypertrophy or expression of the fetal gene program in Pkm2KOi mice post MI, as compared to vehicle control animals (P < 0.01), correlating with smaller infarct size, improved mitochondrial (mt) function, enhanced angiogenesis, reduced degree of CM apoptosis, and reduced oxidative stress post MI. There was significantly higher numbers of dividing CM in the infarct zone between 3-9 days post MI (P < 0.001). Mechanistically, we determined that Pkm2 interacts with β-catenin (Ctnnb1) in the cytoplasm of CM, inhibiting Ctnnb1 phosphorylation at serine 552 and tyrosine 333, by Akt. In the absence of Pkm2, Ctnnb1 translocates to the nucleus leading to transcriptional activation of proliferation-associated target genes. All these effects are abrogated by genetic co-deletion of Pkm2 and Ctnnb1. Collectively, this work supports a novel antiproliferative function for Pkm2 in CM through the sequestration of Ctnnb1 in the cytoplasm of CM whereas loss of Pkm2 is essential for CM proliferation. Reducing cardiac Pkm2 expression may provide a useful strategy for cardiac repair after MI in patients.

Absence of EpCAM in cervical cancer cells is involved in sluginduced epithelial-mesenchymal transition

Background

Slug (Snai2) is a pivotal player in initiating epithelial-mesenchymal transition (EMT) through its trans-suppression effect on E-cadherin in various normal and malignant cells. In this study, the positive effect of Slug on promoting cell motility and metastasis in cervical cancer was further confirmed in this study.

Methods

RNA-Seq was performed to explore the potential molecules that participate in Slug-mediated EMT in cervical cancer cells. The negative correlation between Slug and EpCAM expression in cervical cancer cells was detected in this study, and linked them with in vitro migration and invasion assay, in vivo metastasis experiments, luciferase reporter assay and Chromatin immunoprecipitation.

Results

Transcriptome sequencing analysis revealed that epithelial cell adhesion molecule (EpCAM) was significantly decreased in Slug-overexpressing SiHa cells. Simultaneously, an absence of EpCAM expression was observed in Slug-overexpressing cells. Further studies revealed the trans-suppression effect of Slug on EpCAM through its binding to the E-boxes in the proximal promoter region of EpCAM in cervical cancer cells. Restoring EpCAM in Slug-overexpressing cells by transiently transfecting an EpCAM recombinant plasmid attenuated cell motility and promoted cell growth. Moreover, the negative correlation between Slug and EpCAM expression in human squamous cervical carcinoma (SCC) samples was verified by using Pearson correlation analysis.

Conclusions

These results demonstrated that the absence of EpCAM under Slug expression in cervical cancer cells probably participated in Slug-regulated EMT and further promoted tumor metastasis. Additionally, this study supports a potential way for Slug to initiate EMT progression in cervical cancer cells in addition to inhibiting E-cadherin.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-01858-3.

Msi1 inhibits cervical cancer cell apoptosis by downregulating BAK through AKT signaling

Musashi-1 (Msi1) is an RNA binding protein that functions as a regulator in multiple carcinomas. Our previous study demonstrated that Msi1 could promote the proliferation of cervical cancer cells by targeting the cell cycle proteins P21, P27 and P53. However, the mechanisms by which Msi1 affects the survival of cervical cancer cells, such as apoptosis, are still unclear. In this study, we found that the expression of Msi1 inhibited cervical cancer cell apoptosis in vitro and in vivo. Furthermore, the expression of Msi1 downregulated the expression of PTEN, while AKT signaling was activated, which resulted in a reduction in the proapoptotic protein BAK. In addition, rescue the expression of BAK in Msi1 expressing cervical cancer cells induced the increase of apoptosis cells. These findings indicate that Msi1 regulates cervical cancer cell apoptosis by inhibiting PTEN and activating AKT signaling, which leads to the downregulation of BAK.

HOXB4 inhibits the proliferation and tumorigenesis of cervical cancer cells by downregulating the activity of Wnt/β-catenin signaling pathway

Homeobox B4 (HOXB4), which belongs to the homeobox (HOX) family, possesses transcription factor activity and has a crucial role in stem cell self-renewal and tumorigenesis. However, its biological function and exact mechanism in cervical cancer remain unknown. Here, we found that HOXB4 was markedly downregulated in cervical cancer. We demonstrated that HOXB4 obviously suppressed cervical cancer cell proliferation and tumorigenic potential in nude mice. Additionally, HOXB4-induced cell cycle arrest at the transition from the G0/G1 phase to the S phase. Conversely, loss of HOXB4 promoted cervical cancer cell growth both in vitro and in vivo. Bioinformatics analyses and mechanistic studies revealed that HOXB4 inhibited the activity of the Wnt/β-catenin signaling pathway by direct transcriptional repression of β-catenin. Furthermore, β-catenin re-expression rescued HOXB4-induced cervical cancer cell defects. Taken together, these findings suggested that HOXB4 directly transcriptional repressed β-catenin and subsequently inactivated the Wnt/β-catenin signaling pathway, leading to significant inhibition of cervical cancer cell growth and tumor formation.

Argonaute 3 (AGO3) promotes malignancy potential of cervical cancer via regulation of Wnt/β-catenin signaling pathway

We aimed to investigate the biological roles of Argonaute 3 (AGO3) in cervical cancer. RNA profiles containing 306 cervical cancer tissues and 13 normal samples revealed that AGO3 was significantly up-regulated in cervical cancer, and the expression of AGO3 was negatively associated with the outcome of cervical cancer patients. Cell proliferation and transwell assays showed that the depletion of AGO3 markedly inhibited cervical cancer cell growth and mobility. Importantly, we detected that knockdown of AGO3 exerted suppressive effect on cellular behaviors via inactivating Wnt/β-catenin signaling pathway. Collectively, we conclude that AGO3 is a novel tumor promoter in cervical cancer and has a potential to be a drug target and prognostic predictor of cervical cancer patients.

Expression of Twist, Slug and Snail in esophageal squamous cell carcinoma and their prognostic significance

Esophageal cancer is one of the most common types of malignancy worldwide. At present, surgical resection is the main treatment for esophageal cancer, but recurrence and distant metastasis are the main causes of mortality. The transcription factors Twist, Slug and Snail regulate epithelial-mesenchymal transition and thereby participate in tumor invasion and metastasis. The aim of the present study was to investigate the expression of Twist, Slug and Snail in esophageal squamous cell carcinoma (ESCC) and their prognostic significance. The expression of Twist, Slug and Snail in 229 paraffin-embedded ESCC and matched normal mucosal tissues was detected by immunohistochemistry. The expression differences of Twist, Slug and Snail in the ESCC and normal tissues were compared by χ² test, and the associations between the three proteins and the clinicopathological parameters of ESCC were analyzed. The expression levels of Twist, Slug and Snail in 29 fresh frozen ESCC and matched normal mucosal tissues were detected by reverse transcription-quantitative PCR. The correlations among Twist, Slug and Snail in ESCC were examined by Pearson's correlation analyses. In addition, single factor and multivariate Cox regression analyses were used to analyze the influence of Twist, Slug and Snail on the prognosis of ESCC. Twist was found to be highly expressed in ESCC. The difference of Slug expression in ESCC was associated with differentiation degree, TNM stage and vascular invasion, but no significant association was observed between Snail expression and any clinicopathological parameters. In ESCC, there were significant differences in protein expression between Twist and Snail, and Slug and Snail. The mRNA expression level of Twist in ESCC was significantly higher than that in normal esophageal mucosa. However, the mRNA expression of Slug in normal esophageal mucosa was higher than that in ESCC, and the mRNA expression levels of Twist and Snail were positively correlated in ESCC. Kaplan-Meier analysis of 229 patients with ESCC revealed that Snail influenced the overall survival, as did the co-expression of Twist and Snail. Nerve invasion was also identified as an independent factor affecting the progression-free survival of ESCC. The results indicate that Twist is highly expressed, Slug may be a tumor suppressor, and Snail is an independent prognostic factor in ESCC. Twist and Snail are positively correlated, and the simultaneous inhibition of Twist and Snail protein expression may be beneficial for prolonging the overall survival of patients with ESCC.

Hexokinase 2 Promotes Cell Growth and Tumor Formation Through the Raf/MEK/ERK Signaling Pathway in Cervical Cancer

Hexokinase 2 (HK2) is a member of the hexokinases (HK) that has been reported to be a key regulator during glucose metabolism linked to malignant growth in many types of cancers. In this study, stimulation of HK2 expression was observed in squamous cervical cancer (SCC) tissues, and HK2 expression promoted the proliferation of cervical cancer cells in vitro and tumor formation in vivo by accelerating cell cycle progression, upregulating cyclin A1, and downregulating p27 expression. Moreover, transcriptome sequencing analysis revealed that MAPK3 (ERK1) was upregulated in HK2-overexpressing HeLa cells. Further experiments found that the protein levels of p-Raf, p-MEK1/2, ERK1/2, and p-ERK1/2 were increased in HK2 over-expressing SiHa and HeLa cells. When ERK1/2 and p-ERK1/2 expression was blocked by an inhibitor (FR180204), reduced cyclin A1 expression was observed in HK2 over-expressing cells, with induced p27 expression and inhibited cell growth. Therefore, our data demonstrated that HK2 promoted the proliferation of cervical cancer cells by upregulating cyclin A1 and down-regulating p27 expression through the Raf/MEK/ERK signaling pathway.

Markers of Angiogenesis, Lymphangiogenesis, and Epithelial-Mesenchymal Transition (Plasticity) in CIN and Early Invasive Carcinoma of the Cervix: Exploring Putative Molecular Mechanisms Involved in Early Tumor Invasion

The establishment of a proangiogenic phenotype and epithelial-to-mesenchymal transition (EMT) are considered as critical events that promote the induction of invasive growth in epithelial tumors, and stimulation of lymphangiogenesis is believed to confer the capacity for early dissemination to cancer cells. Recent research has revealed substantial interdependence between these processes at the molecular level as they rely on common signaling networks. Of great interest are the molecular mechanisms of (lymph-)angiogenesis and EMT associated with the earliest stages of transition from intraepithelial development to invasive growth, as they could provide the source of potentially valuable tools for targeting tumor metastasis. However, in the case of early-stage cervical cancer, the players of (lymph-)angiogenesis and EMT processes still remain substantially uncharacterized. In this study, we used RNA sequencing to compare transcriptomes of HPV(+) preinvasive neoplastic lesions and early-stage invasive carcinoma of the cervix and to identify (lymph-)angiogenesis- and EMT-related genes and pathways that may underlie early acquisition of invasive phenotype and metastatic properties by cervical cancer cells. Second, we applied flow cytometric analysis to evaluate the expression of three key lymphangiogenesis/EMT markers (VEGFR3, MET, and SLUG) in epithelial cells derived from enzymatically treated tissue specimens. Overall, among 201 differentially expressed genes, a considerable number of (lymph-)angiogenesis and EMT regulatory factors were identified, including genes encoding cytokines, growth factor receptors, transcription factors, and adhesion molecules. Pathway analysis confirmed enrichment for angiogenesis, epithelial differentiation, and cell guidance pathways at transition from intraepithelial neoplasia to invasive carcinoma and suggested immune-regulatory/inflammatory pathways to be implicated in initiation of invasive growth of cervical cancer. Flow cytometry showed cell phenotype-specific expression pattern for VEGFR3, MET, and SLUG and revealed correlation with the amount of tumor-infiltrating lymphocytes at the early stages of cervical cancer progression. Taken together, these results extend our understanding of driving forces of angiogenesis and metastasis in HPV-associated cervical cancer and may be useful for developing new treatments.

HOXA5 inhibits the proliferation and neoplasia of cervical cancer cells via downregulating the activity of the Wnt/β-catenin pathway and transactivating TP53

HOXA5 is considered a regulator involved in embryonic development and cellular differentiation and a tumor suppressor. Nevertheless, its biological role in cervical carcinoma is still unclear. In the present study, immunohistochemistry showed that HOXA5 expression gradually decreased as the degree of cervical lesions deepened. Ectopic expression of HOXA5 restrained cell proliferation, decreased cell viability, and inhibited tumor formation in vitro and in vivo. Furthermore, the expression of HOXA5 could arrest cell cycle from G0/G1 to S phase. RNA-seq revealed that p21 and cyclinD1 were involved in this process. Moreover, the gene set enrichment analysis and the TOP/FOP reporter assay both suggested that HOXA5 could restrain the activity of the Wnt/β-catenin pathway. Further study using dual-luciferase reporter assay and quantitative chromatin immunoprecipitation assay demonstrated that HOXA5 could directly bind to the TAAT motif within the promoter of TP53 by its HD domain and transactivate TP53, which can upregulate p21. Altogether, our data suggest that HOXA5 inhibits the proliferation and neoplasia via repression activity of the Wnt/β-catenin pathway and transactivating TP53 in cervical cancer.

Downregulation of histone methyltransferase SET8 inhibits progression of hepatocellular carcinoma

The expression of lysine methyltransferase SET8, which is involved in carcinogenesis of many types of human cancers through monomethylation of histone H4 lysine 20 (H4K20), is associated with the prognosis of hepatocellular carcinoma (HCC). We performed a functional analysis for SET8 to assess its effect on HCC progression. SET8 knockdown inhibited proliferation, migration and invasion of HCC cells. SET8 knockdown also inhibited tumour growth in a human xenograft mouse model. Overexpression of SET8 displayed the reverse effect, while treatment with the SET8 inhibitor UNC0379 produced an effect similar to SET8 knockdown. In addition, drug sensitivity testing in SET8-siRNA transfected HCC cells indicated that docetaxel inhibited cell growth dramatically, as demonstrated by the Cell Counting Kit-8 (CCK-8) assay. Furthermore, gene expression microarray analysis showed that genes altered after SET8 knockdown were clustered in pathways related to tumorigenesis and metastasis. Our data suggests that targeting SET8 for HCC therapy can inhibit the proliferation and invasion of HCC cells as well as increase their sensitivity to chemotherapy.

SALL4 promotes the tumorigenicity of cervical cancer cells through activation of the Wnt/β-catenin pathway via CTNNB1

SALL4 is overexpressed in many cancers and is found to be involved in tumorigenesis and tumor progression. However, the function of SALL4 in cervical cancer remains unknown. Here, we showed that the expression of SALL4 was gradually increased from normal cervical tissue to high-grade squamous intraepithelial lesions and then to squamous cervical carcinoma. SALL4 was upregulated or downregulated in cervical cancer cells by stably transfecting a SALL4-expressing plasmid or a shRNA plasmid targeting SALL4, respectively. In vitro, cell growth curves and MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide) assays showed that SALL4 promoted the cell proliferation of cervical cancer cells. In vivo, xenograft experiments verified that SALL4 enhanced the tumor formation of cervical cancer cells in female BALB/c Nude mice. Cell cycle analysis by fluorescence-activated cell sorting found that SALL4 accelerates cell cycle transition from the G0 /G1 phase to the S phase. TOP/FOP-Flash reporter assay revealed that SALL4 significantly upregulates the activity of Wnt/β-catenin pathway. Western blotting showed that the expression levels of β-catenin and important downstream genes, including c-Myc and cyclin D1, were increased by SALL4 in cervical cancer cells. Furthermore, dual-luciferase reporter and chromatin immunoprecipitation assays confirmed that SALL4 transcriptionally activated CTNNB1 by physically interacting with its promoters. Taken together, The results of this study demonstrated that SALL4 may promote cell proliferation and tumor formation of cervical cancer cells by upregulating the activity of the Wnt/β-catenin signaling pathway by directly binding to the CTNNB1 promoter and trans-activating CTNNB1.

Gefitinib suppresses cervical cancer progression by inhibiting cell cycle progression and epithelial-mesenchymal transition

Cervical cancer (CC) is the second most common malignant cancer among women. Gefitinib was one of the first-generation epidermal growth factor receptor-tyrosine kinase inhibitors in clinical trials. However, the underlying mechanism of gefitinib in regulating CC progression remains unknown. In the current study, two CC cell lines, HeLa and Siha, were used to investigate the effects of gefitinib. Cell counting kit-8 assays demonstrated that treatment with gefitinib exerted strong cytotoxicity in HeLa and Siha cells. Flow cytometry was used to examine cell cycle progression and apoptosis. Treatment with gefitinib enhanced the number of cells in the G₀/G₁ phase and increased apoptosis in HeLa and Siha cells. Furthermore, treatment with gefitinib decreased the protein expression level of Bcl-2 and increased the protein expression level of Bax. Taken together, these results suggest that gefitinib may suppress CC cell proliferation and induce cell cycle arrest and apoptosis. The current study also demonstrated that treatment with gefitinib suppressed epithelial-mesenchymal transition (EMT) as the expression level of the epithelial marker, E-cadherin was increased, while the expression level of the mesenchymal marker, vimentin was decreased. The current study demonstrated that treatment with gefitinib decreased the protein expression levels of phosphorylated-GSK3β and β-catenin, which suggests that gefitinib may be a potential novel therapeutic strategy in CC by suppressing the Wnt/β-catenin signaling pathway and EMT to inhibit tumor metastasis in CC cells. In conclusion, gefitinib may suppress the EMT process during cell invasion and induce cell apoptosis and cell cycle arrest via inhibition of the Wnt/β-catenin signaling pathway.

REX1 promotes EMT-induced cell metastasis by activating the JAK2/STAT3-signaling pathway by targeting SOCS1 in cervical cancer

ZFP42 zinc finger protein (REX1), a pluripotency marker in mouse pluripotent stem cells, has been identified as a tumor suppressor in several human cancers. However, the function of REX1 in cervical cancer remains unknown. Both IHC and western blot assays demonstrated that the expression of REX1 protein in cervical cancer tissue was much higher than that in normal cervical tissue. A xenograft assay showed that REX1 overexpression in SiHa and HeLa cells facilitated distant metastasis but did not significantly affect tumor formation in vivo. In addition, in vitro cell migration and invasion capabilities were also promoted by REX1. Mechanistically, REX1 overexpression induced epithelial-to-mesenchymal transition (EMT) by upregulating VIMENTIN and downregulating E-CADHERIN. Furthermore, the JAK2/STAT3-signaling pathway was activated in REX1-overexpressing cells, which also exhibited increased levels of p-STAT3 and p-JAK2, as well as downregulated expression of SOCS1, which is an inhibitor of the JAK2/STAT3-signaling pathway, at both the transcriptional and translational levels. A dual-luciferase reporter assay and qChIP assays confirmed that REX1 trans-suppressed the expression of SOCS1 by binding to two specific regions of the SOCS1 promoter. Therefore, all our data suggest that REX1 overexpression could play a crucial role in the metastasis and invasion of cervical cancer by upregulating the activity of the JAK2/STAT3 pathway by trans-suppressing SOCS1 expression.

Wnt Signaling in Cancer Metabolism and Immunity

The Wingless (Wnt)/β-catenin pathway has long been associated with tumorigenesis, tumor plasticity, and tumor-initiating cells called cancer stem cells (CSCs). Wnt signaling has recently been implicated in the metabolic reprogramming of cancer cells. Aberrant Wnt signaling is considered to be a driver of metabolic alterations of glycolysis, glutaminolysis, and lipogenesis, processes essential to the survival of bulk and CSC populations. Over the past decade, the Wnt pathway has also been shown to regulate the tumor microenvironment (TME) and anti-cancer immunity. Wnt ligands released by tumor cells in the TME facilitate the immune evasion of cancer cells and hamper immunotherapy. In this review, we illustrate the role of the canonical Wnt/β-catenin pathway in cancer metabolism and immunity to explore the potential therapeutic approach of targeting Wnt signaling from a metabolic and immunological perspective.

CDCA2 promotes the proliferation of colorectal cancer cells by activating the AKT/CCND1 pathway in vitro and in vivo

BACKGROUND

Cell division cycle associated 2 (CDCA2), upregulated in lung adenocarcinoma and oral squamous cell carcinoma, may be related to some malignant diseases. Nevertheless, its role in colorectal cancer (CRC) remains unknown.

METHODS

CDCA2 expression was analyzed using The Cancer Genome Atlas (TCGA), quantitative real-time PCR (qRT-PCR), and immunohistochemistry. The impact of CDCA2 on cell proliferation was analyzed via loss- or gain-of-function assays. Furthermore, gene set enrichment analysis was conducted to explore the potential mechanism of CDCA2 in CRC. Lastly, the expression levels of CCND1 and AKT were measured in CRC cell lines.

RESULTS

Our study revealed that CDCA2 expression was associated with tumor progression. Through loss- or gain-of-function assays, we found that upregulation of CDCA2 promoted the proliferation of DLD-1 cells, however, downregulation of CDCA2 in SW480 cells restrained proliferative capacity both in vitro and in vivo. The results of flow cytometry showed that CDCA2 promoted cell cycle progression via upregulation of CCND1 in CRC cell lines. In the following experiments, we found that CDCA2 regulated CCND1 expression through activating the PI3K/AKT pathway, and confirmed this using a specific PI3K inhibitor (LY294002).

CONCLUSIONS

This study demonstrates that overexpression of CDCA2 might target CCND1 to promote CRC cell proliferation and tumorigenesis through activation of the PI3K/AKT pathway.

GDF15 promotes the proliferation of cervical cancer cells by phosphorylating AKT1 and Erk1/2 through the receptor ErbB2

BACKGROUND

Growth differentiation factor 15 (GDF15) is a member of the TGF-β superfamily, and evidence suggests that a substantial amount of GDF15 is secreted in various human cancers, such as ovarian cancer, prostate cancer, and breast cancer, among others. However, the function of GDF15 in cervical cancer has not yet been reported.

METHODS

Immunohistochemistry was used to detect GDF15 expression in normal cervix and in different cervical cancer lesions. Cell growth curves, MTT, tumor formation assays and flow cytometry were utilized to observe the effects of ectopic GDF15 expression on the proliferation and cell cycle of cervical cancer cells. Real-time PCR, western blotting and immunoprecipitation assays were conducted to measure the expression of genes related to the cell cycle and the PI3K/AKT and MAPK/ERK signaling pathways. A chromatin immunoprecipitation assay was performed to confirm whether C-myc bound to a specific region of the GDF15 promoter. Inhibitor treatment and immunoprecipitation assays were employed to identify the association between GDF15 and ErbB2.

RESULTS

GDF15 expression gradually increased during the progression of cervical carcinogenesis. GDF15 promoted cervical cancer cell proliferation via exogenous rhGDF15 treatment or the use of gene editing technology in vitro and in vivo and significantly accelerated the cell cycle transition from G0/G1 to S phase. The expression of p-ErbB2, p-AKT1, p-Erk1/2, CyclinD1 and CyclinE1 was up-regulated and the expression of p21 was down-regulated in GDF15-overexpressing and rhGDF15-treated cervical cancer cells. C-myc trans-activated GDF15 expression by binding to the E-box motifs in the promoter of GDF15 and contributed to the positive feedback of GDF15/C-myc/GDF15. Furthermore, GDF15 bound to ErbB2 in a protein complex in cervical cancer cells.

CONCLUSIONS

Our data demonstrated that GDF15 promoted the proliferation of cervical cancer cells via the up-regulation of CyclinD1 and CyclinE1 and the down-regulation of p21 through both the PI3K/AKT and MAPK/ERK signaling pathways in a complex with ErbB2.

Wnt signaling in cervical cancer?

Cervical cancer (CC) is the second most common malignant cancer in women. CC is difficult to diagnose, has a high recurrence rate, and is resistant to systemic therapies; as a result, CC patients have a relatively poor prognosis. One potential link to CC is the Wnt signaling pathway and its downstream effectors, which regulate cell differentiation, proliferation, migration, and fate. The aberrant activation of Wnt signaling is associated with various cancers, including CC. Recent studies have shown that activating or inhibiting the intracellular signal transduction in this pathway can regulate cancer cell growth and viability. This review will summarize the experimental evidence supporting the significance of the Wnt signaling pathway in CC, and will also discuss the current clinical role of Wnt signaling in CC diagnosis, therapy, and prognosis.

The relationship between cervical precancerous lesion galectin-3 and p27 protein expression and clinical prognosis

The relationship between galectin-3 and p27^kip1 protein expression levels in cervical precancerous lesions and clinical prognosis were studied. A total of 74 patients with cervical intraepithelial neoplasia [(CIN), 20 cases classified as stage I, 24 cases as stage II and 30 cases as stage III] were enrolled in this study. Tissue galectin-3, p27^kip1, vascular endothelial growth factor (VEGF)-2 and cyclin D protein levels were detected via immunohistochemical staining and reverse transcription polymerase chain reaction (PCR). Follow-up median duration was 13.5 months and recurrence rate was determined. Galectin-3, VEGF-2, and cyclin D expression was elevated in patients with higher stage CIN, whereas p27^kip1 showed the opposite trend (p<0.05). During follow-up, there were 3 cases (15.0%) of recurrence in the CIN-I group, 5 cases (20.8%) in the CIN-II group and 9 cases (30.0%) in CIN-III the group. No significant difference in recurrence rate was noted among the groups (p>0.05). The upregulation of galectin-3 and downregulation of p27^kip1 in CIN tissues may be related to tumor progression. This phenomenon will require further verification.

Complement C5a/C5aR pathway potentiates the pathogenesis of gastric cancer by down-regulating p21 expression

Although the complement C5a/C5aR pathway is suggested to play a critical role in tumor pathogenesis, the underlying mechanism has yet to be fully elucidated. In the present study, we found that in patients with gastric cancer in different clinical stages (from stageⅠto stage Ⅳ), both C5aR and p-PI3K/AKT levels were significantly higher in tumoral tissues than in adjacent non-tumoral tissues. In contrast, p21/p-p21 levels were significantly lower in tumoral tissues than in adjacent non-tumoral tissues. In vitro recombinant C5a administration remarkably promoted p-PI3K/p-AKT expression, but inhibited p21/p-p21 expression. Blockage of C5a/C5aR signaling with a C5aR antagonist reversed the C5a-induced inhibitory effect on p21/p-p21 expression. C5a administration to cells pre-treated with a PI3K inhibitor also prevented this inhibitory effect, suggesting the involvement of the PI3K/AKT signaling pathway in C5a/C5aR-mediated suppression of p21/p-p21 expression. In vivo C5aR antagonist treatment caused significant reduction in tumor growth in mice, accompanied by a remarkable elevation in p21/p-p21 expression and reduction in p-PI3K/AKT activation. These results indicate that the C5a/C5aR pathway promotes gastric cancer pathogenesis by suppressing p21/p-p21 expression via activation of PI3K/AKT signaling.

Induction of Slug by Chronic Exposure to Single-Walled Carbon Nanotubes Promotes Tumor Formation and Metastasis

Carbon nanotubes (CNTs) represent a major class of engineered nanomaterials that are being used in diverse fields. However, their use has increasingly become a concern because of their carcinogenic potential. Accumulating evidence has demonstrated that certain types of CNTs are carcinogenic or tumor-promoting in animal models. However, the underlying molecular and cellular mechanisms are unclear. Here, we report that chronic exposure to single-walled (SW) CNTs results in the induction of Slug, a key transcription factor that induces an epithelial-mesenchymal transition (EMT), in human lung epithelial cells. We show that SWCNT-induced Slug upregulation plays a critical role in the aggressive phenotype of SWCNT-exposed cells, which includes increased cell migration, invasion, and anchorage-independent cell growth. Our in vivo studies also show that SWCNT-induced Slug upregulation and EMT activation play a pivotal role in tumor formation and metastasis. Our findings illustrate a direct link between CNT-induced Slug upregulation, EMT activation, and tumor formation and metastasis, and they highlight the potential of CNT-induced Slug upregulation as a target for future risk assessment and prevention of CNT-associated diseases.

MicroRNA-92a Promotes Cell Proliferation in Cervical Cancer via Inhibiting p21 Expression and Promoting Cell Cycle Progression

MicroRNA-92a (miR-92a) generally plays a promoting role in human cancers, but the underlying mechanism in cervical cancer remains unclear. Here we studied the expression and clinical significance of miR-92a in cervical cancer, as well as the regulatory mechanism in the proliferation of cervical cancer cells. Our data indicated that miR-92a was significantly upregulated in cervical cancer tissues compared to their matched adjacent nontumor tissues (ANTs), and the increased miR-92a levels were significantly associated with a higher grade, lymph node metastasis, and advanced clinical stage in cervical cancer. In vitro study revealed that inhibition of miR-92a led to a significant reduction in the proliferation of HeLa cells via induction of cell cycle arrest at the G₁ stage. In contrast, overexpression of miR-92a markedly promoted the proliferation of HeLa cells by promoting cell cycle progression. Further investigation revealed that miR-92a has a negative effect on protein levels, but not the mRNA levels, of p21 in HeLa cells, suggesting that p21 is a direct target of miR-92a. Overexpression of p21 eliminated the promoting effects of miR-92a on the proliferation and cell cycle progression of HeLa cells. However, knockdown of p21 reversed the suppressive effects of miR-92a downregulation on HeLa cell proliferation and cell cycle progression. Moreover, p21 was significantly downregulated in cervical cancer tissues compared to ANTs, suggesting that the increased expression of miR-92a may contribute to the decreased expression of p21, which further promotes cervical cancer growth. In conclusion, our study demonstrates that miR-92a promotes the proliferation of cervical cancer cells via inhibiting p21 expression and promoting cell cycle progression, highlighting the clinical significance of miR-92a in cervical cancer.