Inhibiting of self-renewal, migration and invasion of ovarian cancer stem cells by blocking TGF-β pathway

FBXO28 promotes cell proliferation, migration and invasion via upregulation of the TGF-beta1/SMAD2/3 signaling pathway in ovarian cancer

BACKGROUND

Ovarian cancer is one of the most common gynecological malignancies due to the lack of early symptoms, early diagnosis and limited screening. Therefore, it is necessary to understand the molecular mechanism underlying the occurrence and progression of ovarian cancer and to identify a basic biomarker for the early diagnosis and clinical treatment of ovarian cancer.

METHODS

The association between FBXO28 and ovarian cancer prognosis was analyzed using Kaplan‒Meier survival analysis. The difference in FBXO28 mRNA expression between normal ovarian tissues and ovarian tumor tissues was obtained from The Cancer Genome Atlas (TCGA), and Genotype-Tissue Expression (GTEx) cohorts. The expression levels of the FBXO28 protein in ovarian cancer tissues and normal ovarian tissues were measured via immunohistochemical staining. Western blotting was used to determine the level of FBXO28 expression in ovarian cancer cells. The CCK-8, the colony formation, Transwell migration and invasion assays were performed to evaluate cell proliferation and motility.

RESULTS

We found that a higher expression level of FBXO28 was associated with poor prognosis in ovarian cancer patients. Analysis of the TCGA and GTEx cohorts showed that the FBXO28 mRNA level was lower in normal ovarian tissue samples than in ovarian cancer tissue samples. Compared with that in normal ovarian tissues or cell lines, the expression of FBXO28 was greater in ovarian tumor tissues or tumor cells. The upregulation of FBXO28 promoted the viability, proliferation, migration and invasion of ovarian cancer cells. Finally, we demonstrated that FBXO28 activated the TGF-beta1/Smad2/3 signaling pathway in ovarian cancer.

CONCLUSIONS

In conclusion, FBXO28 enhanced oncogenic function via upregulation of the TGF-beta1/Smad2/3 signaling pathway in ovarian cancer.

Kindlin-2 regulates colonic cancer stem-like cells survival and self-renewal via Wnt/β-catenin mediated pathway

BACKGROUND

Cancer Stem Cells (CSCs) have emerged as a critical mediator in recurrence and resistance in cancers. Kindlin-isoform (1 and 2) binds with cytoplasmic β-tail of integrin and are essential co-activators of integrin function. Given their important function in regulating cancer hallmarks such as cell proliferation, invasion, migration, and metastasis, we hypothesize that it might play a critical role in CSC growth, survival, and self-renewal of colon cancer.

MATERIALS AND METHODS

Using knockdown approaches, we inhibited Kindlin-2 expression in HCT116 and HT29 colon cancer cells. Extreme limiting dilution and self-renewal assay were performed to measure the role of Kindlin in colonic CSC. Standard methods such as qRT-PCR and western blotting were carried out to understand the signaling cascade by which Kindlin regulates CSC marker expression and downstream targets.

RESULTS

Our data show isoform-specific upregulation of Kindlin-2 in colonic CSCs. The silencing of Kindlin-2 reduces colonosphere formation, decreases CSC size, and self-renewal marker genes such as CD-133, CXCR-4, LGR-5, and C-MYC. Kindlin-2 silencing reduces colonosphere proliferation, invasion, and migration of colonic CSCs. Mechanistically, Kindlin-2 silencing reduces the expression, and nuclear localization of β-catenin, and decreases β-catenin target genes such as C-MYC, cyclin D1, DKK-1, and Snail-1.

CONCLUSION

Our study delineates the isoform-specific activity of Kindlin-2 in regulating Colonic CSC. Isoform-specific targeting of Kindlin-2 may be a novel strategy to tackle this devastating disease.

Assessment of the effectiveness of the peptide inhibitor homologous to the transforming growth factor β cytokine blocking the TGFβRI/TGFβRII receptor complex-pilot study

BACKGROUND

A key player in the fibrotic process is the transforming growth factor β (TGF-β) which enhances extracellular matrix production by increasing the transcription of matrix proteins. The cytokine TGF-β first binds to the TGFβRII receptor (dimer), resulting in the recruitment of the TGFβRI receptor (dimer). The complex thus formed leads to the phosphorylation of the kinase domain of TGFβRI, which in turn results in activation of the Smad pathway. This is therefore a targeted pathway for research into the application of peptide inhibitors in blocking the TGF-β-Smad signaling pathway. The aim of this study was to design a peptide inhibitor (homologous to the cytokine TGF-β) which, after binding to the TGFβRI/TGFβRII receptor, would block the cytokine binding and thus prevent the formation of an activating complex.

METHODS

Preliminary work on the design and synthesis of inhibitors for TGFβRI/TGFβRII has allowed us to identify and describe five key regions of the TGF-β-TGFβRI/TGFβRII interface. The following five peptide inhibitors were synthesized for Region 1: 1.1 ALDAAYCFR, 1.2 LDAAYCFRN, 1.3 DAAYCFRNV, 1.4 AAYCFRNVQ, 1.5 AYCFRNVQD. The expression of the SEAP reporter gene, Smad2, Smad3, Smad4, and JNK1 gene was measured using quantitative real-time polymerase chain reaction.

RESULTS

For Region 1 peptide inhibitors tested for TGFβRI/TGFβRII, reduced SEAP (reporter gene) expression was observed in cells of the MFB-F11 line, which suggests inhibited the formation of cytokine-receptor complexes.

CONCLUSIONS

For IP1_2, 1_3 and 1_5 Region 1 peptides tested for TGFβRI/TGFβRII, reduced cytokine-receptor signal by adding newly designed inhibitors. The study revealed an impact of these peptide inhibitors on the reduction of mRNA expression of Smad2, Smad3, Smad4 and JNK1 genes.

System analysis based on the pyroptosis-related genes identifes GSDMD as a novel therapy target for skin cutaneous melanoma

BACKGROUND

Skin cutaneous melanoma (SKCM) is the most aggressive skin cancer, accounting for more than 75% mortality rate of skin-related cancers. As a newly identified programmed cell death, pyroptosis has been found to be closely associated with tumor progression. Nevertheless, the prognostic significance of pyroptosis in SKCM remains elusive.

METHODS

A total of 469 SKCM samples and 812 normal samples were obtained from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases. Firstly, differentially expressed pyroptosis-related genes (PRGs) between normal samples and SKCM samples were identified. Secondly, we established a prognostic model based on univariate Cox and LASSO Cox regression analyses, which was validated in the test cohort from GSE65904. Thirdly, a nomogram was used to predict the survival probability of SKCM patients. The R package "pRRophetic" was utilized to identify the drug sensitivity between the low- and high-risk groups. Tumor immune infiltration was evaluated using "immuneeconv" R package. Finally, the function of GSDMD and SB525334 was explored in A375 and A2058 cells.

RESULTS

Based on univariate Cox and LASSO regression analyses, we established a prognostic model with identified eight PRGs (AIM2, CASP3, GSDMA, GSDMC, GSDMD, IL18, NLRP3, and NOD2), which was validated in the test cohort. SKCM patients were divided into low- and high-risk groups based on the median of risk score. Kaplan-Meier survival analysis showed that high-risk patients had shorter overall survival than low-risk patients. Additionally, time-dependent ROC curves validated the accuracy of the risk model in predicting the prognosis of SKCM. More importantly, 4 small molecular compounds (SB525334, SR8278, Gemcitabine, AT13387) were identified, which might be potential drugs for patients in different risk groups. Finally, overexpression of GSDMD and SB525334 treatment inhibit the proliferation, migration, and invasion of SKCM cells.

CONCLUSION

In this study, we constructed a prognostic model based on PRGs and identified GSDMD as a potential therapeutic target, which provide new insights into SKCM treatment.

Loss of miR-6844 alters stemness/self-renewal and cancer hallmark(s) markers through CD44-JAK2-STAT3 signaling axis in breast cancer stem-like cells

MicroRNAs regulate breast stemness and self-renewal properties in breast cancer cells at the molecular level. Recently we reported the clinical relevance and in vitro expression profile of novel miR-6844 in breast cancer and -derived stem-like cells (mammosphere). In the present study, we first time explore the functional role of loss of miR-6844 in breast cancer cells derived mammosphere. Down expression of miR-6844 significantly decreased cell proliferation in MCF-7 and T47D cells derived mammosphere in a time-dependent manner. MiR-6844 down expression reduced the sphere formation in terms of size and number in test cells. Loss of miR-6844 significantly altered stemness and self-renewal markers (Bmi-1, Nanog, c-Myc, Sox2, and CD44) in mammosphere compared to negative control spheres. Moreover, loss of miR-6844 inhibits the JAK2-STAT3 signaling pathway by decreasing p-JAK2 and p-STAT3 levels in breast cancer cells derived mammosphere. Loss of miR-6844 expression significantly decreased CCND1 and CDK4 mRNA/protein levels and arrested breast cancer stem-like cells in G2/M phase. Reduced expression of miR-6844 increased Bax/Bcl-2 ratio, late apoptotic cell population, and Caspase 9 and 3/7 activity in the mammosphere. Low expression of miR-6844 decreased migratory and invasive cells by altering the expression of Snail, E-cad, and Vimentin at mRNA/protein levels. In conclusion, loss of miR-6844 decreases stemness/self-renewal and other cancer hallmark in breast cancer stem-like cells through CD44-JAK2-STAT3 axis. Thus, downregulation of miR-6844 by therapeutic agents might be a novel strategy to target breast cancer stemness and self-renewal.

"DEPHENCE" system-a novel regimen of therapy that is urgently needed in the high-grade serous ovarian cancer-a focus on anti-cancer stem cell and anti-tumor microenvironment targeted therapies

Ovarian cancer, especially high-grade serous type, is the most lethal gynecological malignancy. The lack of screening programs and the scarcity of symptomatology result in the late diagnosis in about 75% of affected women. Despite very demanding and aggressive surgical treatment, multiple-line chemotherapy regimens and both approved and clinically tested targeted therapies, the overall survival of patients is still unsatisfactory and disappointing. Research studies have recently brought some more understanding of the molecular diversity of the ovarian cancer, its unique intraperitoneal biology, the role of cancer stem cells, and the complexity of tumor microenvironment. There is a growing body of evidence that individualization of the treatment adjusted to the molecular and biochemical signature of the tumor as well as to the medical status of the patient should replace or supplement the foregoing therapy. In this review, we have proposed the principles of the novel regimen of the therapy that we called the "DEPHENCE" system, and we have extensively discussed the results of the studies focused on the ovarian cancer stem cells, other components of cancer metastatic niche, and, finally, clinical trials targeting these two environments. Through this, we have tried to present the evolving landscape of treatment options and put flesh on the experimental approach to attack the high-grade serous ovarian cancer multidirectionally, corresponding to the "DEPHENCE" system postulates.

Deciphering Common Traits of Breast and Ovarian Cancer Stem Cells and Possible Therapeutic Approaches

Breast cancer (BC) and ovarian cancer (OC) are among the most common and deadly cancers affecting women worldwide. Both are complex diseases with marked heterogeneity. Despite the induction of screening programs that increase the frequency of earlier diagnosis of BC, at a stage when the cancer is more likely to respond to therapy, which does not exist for OC, more than 50% of both cancers are diagnosed at an advanced stage. Initial therapy can put the cancer into remission. However, recurrences occur frequently in both BC and OC, which are highly cancer-subtype dependent. Therapy resistance is mainly attributed to a rare subpopulation of cells, named cancer stem cells (CSC) or tumor-initiating cells, as they are capable of self-renewal, tumor initiation, and regrowth of tumor bulk. In this review, we will discuss the distinctive markers and signaling pathways that characterize CSC, their interactions with the tumor microenvironment, and the strategies they employ to evade immune surveillance. Our focus will be on identifying the common features of breast cancer stem cells (BCSC) and ovarian cancer stem cells (OCSC) and suggesting potential therapeutic approaches.

Leveraging the replication stress response to optimize cancer therapy

High-fidelity DNA replication is critical for the faithful transmission of genetic information to daughter cells. Following genotoxic stress, specialized DNA damage tolerance pathways are activated to ensure replication fork progression. These pathways include translesion DNA synthesis, template switching and repriming. In this Review, we describe how DNA damage tolerance pathways impact genome stability, their connection with tumorigenesis and their effects on cancer therapy response. We discuss recent findings that single-strand DNA gap accumulation impacts chemoresponse and explore a growing body of evidence that suggests that different DNA damage tolerance factors, including translesion synthesis polymerases, template switching proteins and enzymes affecting single-stranded DNA gaps, represent useful cancer targets. We further outline how the consequences of DNA damage tolerance mechanisms could inform the discovery of new biomarkers to refine cancer therapies.

Immunotherapy checkpoints in ovarian cancer vasculogenic mimicry: Tumor immune microenvironments, and drugs

Vasculogenic mimicry (VM), a vessel-like structure independent of endothelial cells, commonly exists in solid tumors which requires blood vessels to grow. As a special source of blood supply for tumor progression to a more aggressive state, VM has been observed in a variety of human malignant tumors and is tightly associated with tumor proliferation, invasion, metastasis, and poor patient prognosis. So far, various factors, including immune cells and cytokines, were reported to regulate ovarian cancer progression by influencing VM formation. Herein, we review the mechanisms that regulate VM formation in ovarian cancer and the effect of cells, cytokines, and signaling molecules in the tumor microenvironment on VM formation, Furthermore, we summarize the current clinical application of drugs targeting VM formation.

Zinc Finger E-Box Binding Homeobox 2 as a Prognostic Biomarker in Various Cancers and Its Correlation with Infiltrating Immune Cells in Ovarian Cancer

This study investigated the expression of zinc finger E-box binding homeobox 2 (ZEB2), its prognostic significance in various cancers, and the correlation between ZEB2 and infiltrating immune cells and ZEB2-related proteins in ovarian cancer (OV). The Gene Expression Profiling Interactive Analysis tool was used to analyze RNA sequencing data and cancer survival rates, based on normal and tumor tissue data available in The Cancer Genome Atlas (TCGA) database. The Kaplan–Meier plotter and PrognoScan databases were used to analyze the prognostic value of ZEB2 in OV (n = 1144). The Tumor Immune Estimation Resource was used to investigate the correlation between ZEB2 and infiltrating immune cells in various cancers, including OV. High ZEB2 expression was associated with a poorer prognosis in OV. In OV, ZEB2 is positively correlated with CD8+T cells, neutrophils, macrophages, and dendritic cell invasion; and ZEB2 is negatively correlated with tumor-infiltrating B cells. The STRING database was used to investigate the correlations with ZEB2-related proteins. The results reveal that ZEB2 was positively correlated with SMAD1 and SMAD2 in OV. Our findings may serve as a potential prognostic biomarker, and provide novel insights into the tumor immunology in OV. Thus, ZEB2 may be a potential diagnostic and therapeutic target in OV.

Multiple roles of mothers against decapentaplegic homolog 4 in tumorigenesis, stem cells, drug resistance, and cancer therapy

The transforming growth factor (TGF)-β signaling pathway controls many cellular processes, including proliferation, differentiation, and apoptosis. Abnormalities in the TGF-β signaling pathway and its components are closely related to the occurrence of many human diseases, including cancer. Mothers against decapentaplegic homolog 4 (Smad4), also known as deleted in pancreatic cancer locus 4, is a typical tumor suppressor candidate gene locating at q21.1 of human chromosome 18 and the common mediator of the TGF-β/Smad and bone morphogenetic protein/Smad signaling pathways. It is believed that Smad4 inactivation correlates with the development of tumors and stem cell fate decisions. Smad4 also interacts with cytokines, miRNAs, and other signaling pathways, jointly regulating cell behavior. However, the regulatory function of Smad4 in tumorigenesis, stem cells, and drug resistance is currently controversial. In addition, Smad4 represents an attractive therapeutic target for cancer. Elucidating the specific role of Smad4 is important for understanding the mechanism of tumorigenesis and cancer treatment. Here, we review the identification and characterization of Smad4, the canonical TGF-β/Smad pathway, as well as the multiple roles of Smad4 in tumorigenesis, stem cells, and drug resistance. Furthermore, we provide novel insights into the prospects of Smad4-targeted cancer therapy and the challenges that it will face in the future.

Epithelial-Mesenchymal Transition and Cancer Stem Cells

Epithelial-mesenchymal transition (EMT), a cellular phenotypic change from epithelial to mesenchymal-like features, is related to the resistance and metastasis of cancer stem cells (CSCs). Several signal transduction mechanisms induce EMT, which causes the gene expression alteration to induce the acquisition of resistance and metastasis in cancer. EMT is characterized with high gene expression of cadherin 2 (N-cadherin) and vimentin, and sparse cell-cell junction. The cells with EMT-phenotype have migration, metastasis and drug-resistance capacity, which are main characteristics of CSCs. It seems that the main population of CSCs exhibits EMT phenotype, whereas some populations consist of phenotypes other than EMT. In this chapter, EMT mechanism, phenotypic features of EMT and CSCs, signal transduction in EMT and CSCs, differences between EMT and CSCs, and the role of EMT in CSCs are described.

Three dimensional in vitro culture systems in anticancer drug discovery targeted on cancer stem cells

Worldwide, tumors are one of the most common causes of death. Every year 3.7 million new cases occur in Europe and more than 1.9 million patients die (WHO data). Most of the fields of research are focused on developing new therapeutic strategies that will be effective in eliminating the tumor, preventing its remission, and avoiding or reducing the side effects of therapy. In the past, generally classical 2D cell cultures or immunodeficient animal models had been used to cultivate and test drugs on human cancer cell lines. Nowadays, there are increasing interests in three-dimensional (3D) cell cultures, a method with significant differences from flat cultured cells, both considering gene expressions and cell-cell interactions. Various evidence suggests that high tumorigenic properties might be dependent on the occurrence of a small cell population, pointed out to be responsible for metastasis and recurrence. This population is called cancer stem cells (CSCs), hinted to have a lot of similarities with normal stem cells. CSCs are the main reason for chemotherapy failure as well as multi-drug resistance (MDR). CSCs can also interact through the cytokine network, with other cells like the macrophages of the inflammatory system. The big advantage of a 3D culture is the possibility to isolate and investigate the CSCs population surrounded by its environment. This article aims to sum up known 3D cell cultures, especially in the field of CSCs research due to the importance of the tumor's environment on stem cell's markers expression and their development.

TGF-β1 Receptor Inhibitor SB525334 Attenuates the Epithelial to Mesenchymal Transition of Peritoneal Mesothelial Cells via the TGF-β1 Signaling Pathway

We investigated the effect of SB525334 (TGF-β receptor type 1 (TβRI) inhibitor) on the epithelial to mesenchymal transition (EMT) signaling pathway in human peritoneal mesothelial cells (HPMCs) and a peritoneal fibrosis mouse model. In vitro experiments were performed using HPMCs. HPMCs were treated with TGF-β1 and/or SB525334. In vivo experiments were conducted with male C57/BL6 mice. The 0.1% chlorhexidine gluconate (CG) was intraperitoneally injected with or without SB52534 administration by oral gavage. Mice were euthanized after 28 days. EMT using TGF-β1-treated HPMCs included morphological changes, cell migration and invasion, EMT markers and collagen synthesis. These pathological changes were reversed by co-treatment with SB525334. CG injection was associated with an increase in peritoneal fibrosis and thickness, which functionally resulted in an increase in the glucose absorption via peritoneum. Co-treatment with SB525334 attenuated these changes. The levels of EMT protein markers and immunohistochemical staining for fibrosis showed similar trends. Immunofluorescence staining for EMT markers showed induction of transformed cells with both epithelial and mesenchymal cell markers, which decreased upon co-treatment with SB525334. SB525334 effectively attenuated the TGF-β1-induced EMT in HPMCs. Cotreatment with SB525334 improved peritoneal thickness and fibrosis and recovered peritoneal membrane function in a peritoneal fibrosis mouse model.

Insight into the role of multiple signaling pathways in regulating cancer stem cells of gynecologic cancers

Mounting evidence has demonstrated that a myriad of developmental signaling pathways, such as the Wnt, Notch, Hedgehog and Hippo, are frequently deregulated and play a critical role in regulating cancer stem cell (CSC) activity in human cancers, including gynecologic malignancies. In this review article, we describe an overview of various signaling pathways in human cancers. We further discuss the developmental roles how these pathways regulate CSCs from experimental evidences in gynecologic cancers. Moreover, we mention several compounds targeting CSCs in gynecologic cancers to enhance the treatment outcomes. Therefore, these signaling pathways might be the potential targets for developing targeted therapy in gynecologic cancers.

Jorunnamycin A Suppresses Stem-Like Phenotypes and Sensitizes Cisplatin-Induced Apoptosis in Cancer Stem-Like Cell-Enriched Spheroids of Human Lung Cancer Cells

It has been recognized that cancer stem-like cells (CSCs) in tumor tissue crucially contribute to therapeutic failure, resulting in a high mortality rate in lung cancer patients. Due to their stem-like features of self-renewal and tumor formation, CSCs can lead to drug resistance and tumor recurrence. Herein, the suppressive effect of jorunnamycin A, a bistetrahydroisoquinolinequinone isolated from Thai blue sponge Xestospongia sp., on cancer spheroid initiation and self-renewal in the CSCs of human lung cancer cells is revealed. The depletion of stemness transcription factors, including Nanog, Oct-4, and Sox2 in the lung CSC-enriched population treated with jorunnamycin A (0.5 μM), resulted from the activation of GSK-3β and the consequent downregulation of β-catenin. Interestingly, pretreatment with jorunnamycin A at 0.5 μM for 24 h considerably sensitized lung CSCs to cisplatin-induced apoptosis, as evidenced by upregulated p53 and decreased Bcl-2 in jorunnamycin A-pretreated CSC-enriched spheroids. Moreover, the combination treatment of jorunnamycin A (0.5 μM) and cisplatin (25 μM) also diminished CD133-overexpresssing cells presented in CSC-enriched spheroids. Thus, evidence on the regulatory functions of jorunnamycin A may facilitate the development of this marine-derived compound as a novel chemotherapy agent that targets CSCs in lung cancer treatment.

Role of exosomes in the immune microenvironment of ovarian cancer

Exosomes are excretory vesicles that can deliver a variety of bioactive cargo molecules to the extracellular environment. Accumulating evidence demonstrates exosome participation in intercellular communication, immune response, inflammatory response and they even play an essential role in affecting the tumor immune microenvironment. The role of exosomes in the immune microenvironment of ovarian cancer is mainly divided into suppression and stimulation. On one hand exosomes can stimulate the innate and adaptive immune systems by activating dendritic cells (DCs), natural killer cells and T cells, allowing these immune cells exert an antitumorigenic effect. On the other hand, ovarian cancer-derived exosomes initiate cross-talk with immunosuppressive effector cells, which subsequently cause immune evasion; one of the hallmarks of cancer. Exosomes induce the polarization of macrophages in M2 phenotype and induce apoptosis of lymphocytes and DCs. Exosomes further activate additional immunosuppressive effector cells (myeloid-derived suppressor cells and regulatory T cells) that induce fibroblasts to differentiate into cancer-associated fibroblasts. Exosomes also induce the tumorigenicity of mesenchymal stem cells to exert additional immune suppression. Furthermore, besides mediating the intercellular communication, exosomes carry microRNAs (miRNAs), proteins and lipids to the tumor microenvironment, which collectively promotes ovarian cancer cells to proliferate, invade and tumors to metastasize. Studying proteins, lipids and miRNAs carried by exosomes could potentially be used as an early diagnostic marker of ovarian cancer for designing treatment strategies.