Met promotes the formation of double minute chromosomes induced by Sei-1 in NIH-3T3 murine fibroblasts

Extracellular vesicle-encapsulated microRNA-296-3p from cancer-associated fibroblasts promotes ovarian cancer development through regulation of the PTEN/AKT and SOCS6/STAT3 pathways

Cancer-associated fibroblasts (CAFs), as important components of the tumor microenvironment, can regulate intercellular communication and tumor development by secreting extracellular vesicles (EVs). However, the role of CAF-derived EVs in ovarian cancer has not been fully elucidated. Here, using an EV-microRNA sequencing analysis, we reveal specific overexpression of microRNA (miR)-296-3p in activated CAF-derived EVs, which can be transferred to tumor cells to regulate the malignant phenotypes of ovarian cancer cells. Moreover, overexpression of miR-296-3p significantly promotes the proliferation, migration, invasion, and drug resistance of ovarian cancer cells in vitro, as well as tumor growth in vivo, while its inhibition has the opposite effects. Further mechanistic studies reveal that miR-296-3p promotes ovarian cancer progression by directly targeting PTEN and SOCS6 and activating AKT and STAT3 signaling pathways. Importantly, increased expression of miR-296-3p encapsulated in plasma EVs is closely correlated with tumorigenesis and chemoresistance in patients with ovarian cancer. Our results highlight the cancer-promoting role of CAF-derived EVs carrying miR-296-3p in ovarian cancer progression for the first time, and suggest that miR-296-3p encapsulated in CAF-derived EVs could be a diagnostic biomarker and therapeutic target for ovarian cancer.

Extrachromosomal DNA (ecDNA) in cancer: mechanisms, functions, and clinical implications

Extrachromosomal DNA (ecDNA) is circular DNA that plays an important role in the development and heterogeneity of cancer. The rapid evolution of methods to detect ecDNA, including microscopic and sequencing approaches, has greatly enhanced our knowledge of the role of ecDNA in cancer development and evolution. Here, we review the molecular characteristics, functions, mechanisms of formation, and detection methods of ecDNA, with a focus on the potential clinical implications of ecDNA in cancer. Specifically, we consider the role of ecDNA in acquired drug resistance, as a diagnostic and prognostic biomarker, and as a therapeutic target in the context of cancer. As the pathological and clinical significance of ecDNA continues to be explored, it is anticipated that ecDNA will have broad applications in the diagnosis, prognosis, and treatment of patients with cancer.

FAPhigh α-SMAlow cancer-associated fibroblast-derived SLPI protein encapsulated in extracellular vesicles promotes ovarian cancer development via activation of PI3K/AKT and downstream signaling pathways

Ovarian cancer is the most lethal gynecological malignancy worldwide with high metastasis and poor prognosis rates. Cancer‐associated fibroblasts (CAFs), a heterogeneous population of cells that constitutes a major component of the tumor microenvironment, secrete extracellular vesicles (EVs) loading with proteins, lipids, and RNAs to promote tumorigenesis. However, the specific roles of CAF‐derived proteins contained in EVs in ovarian cancer remain poorly understood at present. Using the gene expression microarray analysis, we identified a list of dysregulated genes between the α‐SMA⁺CAF and FAP⁺CAF subpopulations, from which secretory leukocyte protease inhibitor (SLPI) was chosen for further validation. Quantitative PCR, western blot, immunohistochemistry, and enzyme‐linked immunosorbent assays were used to assess SLPI expression in ovarian cancer cells, tissues, CAFs, and EVs. Additionally, we evaluated the effects of exogenous SLPI on proliferation, migration, invasion, and adhesion of ovarian cancer cells in vitro. Our results showed SLPI protein was upregulated in CAFs, particularly in the FAP^highα‐SMA^lowCAF subpopulation, and associated with increased tumor grade and decreased overall survival (OS). Importantly, CAF‐derived SLPI protein could be encapsulated in EVs for delivery to ovarian cancer cells, thus facilitating cell proliferation, migration, invasion, and adhesion via activating the PI3K/AKT and downstream signaling pathways. Moreover, high plasma expression of SLPI encapsulated in EVs was closely correlated with tumor stage in ovarian cancer patients. Our collective results highlight an oncogenic role of plasma EV‐encapsulated SLPI secreted by CAFs in tumor progression for the first time, supporting its potential utility as a prognostic biomarker of ovarian cancer.

Extrachromosomal DNA: An Emerging Hallmark in Human Cancer

Human genes are arranged on 23 pairs of chromosomes, but in cancer, tumor-promoting genes and regulatory elements can free themselves from chromosomes and relocate to circular, extrachromosomal pieces of DNA (ecDNA). ecDNA, because of its nonchromosomal inheritance, drives high-copy-number oncogene amplification and enables tumors to evolve their genomes rapidly. Furthermore, the circular ecDNA architecture fundamentally alters gene regulation and transcription, and the higher-order organization of ecDNA contributes to tumor pathogenesis. Consequently, patients whose cancers harbor ecDNA have significantly shorter survival. Although ecDNA was first observed more than 50 years ago, its critical importance has only recently come to light. In this review, we discuss the current state of understanding of how ecDNAs form and function as well as how they contribute to drug resistance and accelerated cancer evolution.

Tribbles Pseudokinases in Colorectal Cancer

The Tribbles family of pseudokinases controls a wide number of processes during cancer on-set and progression. However, the exact contribution of each of the three family members is still to be defined. Their function appears to be context-dependent as they can act as oncogenes or tumor suppressor genes. They act as scaffolds modulating the activity of several signaling pathways involved in different cellular processes. In this review, we discuss the state-of-knowledge for TRIB1, TRIB2 and TRIB3 in the development and progression of colorectal cancer. We take a perspective look at the role of Tribbles proteins as potential biomarkers and therapeutic targets. Specifically, we chronologically systematized all available articles since 2003 until 2020, for which Tribbles were associated with colorectal cancer human samples or cell lines. Herein, we discuss: (1) Tribbles amplification and overexpression; (2) the clinical significance of Tribbles overexpression; (3) upstream Tribbles gene and protein expression regulation; (4) Tribbles pharmacological modulation; (5) genetic modulation of Tribbles; and (6) downstream mechanisms regulated by Tribbles; establishing a comprehensive timeline, essential to better consolidate the current knowledge of Tribbles' role in colorectal cancer.

Extrachromosomal Circular DNAs: Origin, formation and emerging function in Cancer

The majority of cellular DNAs in eukaryotes are organized into linear chromosomes. In addition to chromosome DNAs, genes also reside on extrachromosomal elements. The extrachromosomal DNAs are commonly found to be circular, and they are referred to as extrachromosomal circular DNAs (eccDNAs). Recent technological advances have enriched our knowledge of eccDNA biology. There is currently increasing concern about the connection between eccDNA and cancer. Gene amplification on eccDNAs is prevalent in cancer. Moreover, eccDNAs commonly harbor oncogenes or drug resistance genes, hence providing a growth or survival advantage to cancer cells. eccDNAs play an important role in tumor heterogeneity and evolution, facilitating tumor adaptation to challenging circumstances. In addition, eccDNAs have recently been identified as cell-free DNAs in circulating system. The altered level of eccDNAs is observed in cancer patients relative to healthy controls. Particularly, eccDNAs are associated with cancer progression and poor outcomes. Thus, eccDNAs could be useful as novel biomarkers for the diagnosis and prognosis of cancer. In this review, we summarize current knowledge regarding the formation, characteristics and biological importance of eccDNAs, with a focus on the molecular mechanisms associated with their roles in cancer progression. We also discuss their potential applications in the detection and treatment of cancer. A better understanding of the functional role of eccDNAs in cancer would facilitate the comprehensive analysis of molecular mechanisms involved in cancer pathogenesis.

Prognostic and Clinicopathological Significance of SERTAD1 in Various Types of Cancer Risk: A Systematic Review and Retrospective Analysis

SERTAD/TRIP-Br genes are considered as a key nuclear transcriptional player in diverse mechanisms of cell including carcinogenesis. The Oncomine™-Online Platform was used for differential expression and biological insights. Kaplan-Meier survival estimated by KM-plotter/cBioPortal/PrognoScan with 95% CI. SERTAD1 was found significantly elevated levels in most of tumor samples. Kaplan-Meier Plotter results distinctly showed the SERTAD1 over-expression significantly reduced median overall-survival (OS) of patients in liver (n = 364/Logrank-test p = 0.0015), ovarian (n = 655/Logrank-test p = 0.00011) and gastric (n = 631/Logrank-test p = 0.1866). Increased level of SERTAD1 has a significantly higher survival rate in the initial time period, but after 100 months slightly reduced OS (n = 26/Logrank-test p = 0.34) and RFS in HER2 positive breast cancer patients. In meta-analysis, cancer patients with higher SERTAD1 mRNA fold resulted worse overall survival than those with lower SERTAD1 levels. Heterogeneity was observed in the fixed effect model analysis DFS [Tau² = 0.0.073, Q (df = 4) = 15.536 (p = 0.004), I² = 74.253], DSS [Tau² = 1.015, Q (df = 2) = 33.214, (p = 0.000), I² = 93.973], RFS [Tau² = 0.492, Q (df = 7) = 71.133 (p = 0.000), I² = 90.159] (Figure 5). OS [Tau² = 0.480, Q (df = 17) = 222.344 (p = 0.000), I² = 92.354]. Lastly, SERTAD1 involved in several signaling cascades through interaction and correlation with many candidate factors as well as miRNAs. This meta-analysis demonstrates a robust evidence of an association between higher or lower SERTAD1, alteration and without alteration of SERTAD1 in cancers in terms of survival and cancer invasiveness.

Complex karyotype in myelodysplastic syndromes: Diagnostic procedure and prognostic susceptibility

Complex karyotype (CK) is a poor prognosis factor in hematological malignancies. Studies have shown that the presence of CK in myelodysplastic syndrome (MDS) can be associated with MDS progression to acute myeloid leukemia. The goal of this review was to examine the relationship between different types of CK with MDS, as well as its possible role in the deterioration and progression of MDS to leukemia. The content used in this paper has been obtained by a PubMed and Google Scholar search of English language papers (1975-2018) using the terms complex karyotype and myelodysplastic syndromes. A single independent abnormality can be associated with a good prognosis. However, the coexistence of a series of abnormalities can lead to CK, which is associated with the deterioration of MDS and its progression to leukemia. Therefore, CK may be referred to as a prognostic factor in MDS. The detection of independent cytogenetic disorders that altogether can result in CK could be used as a prognostic model for laboratory and clinical use.

Sei-1 promotes double minute chromosomes formation through activation of the PI3K/Akt/BRCA1-Abraxas pathway and induces double-strand breaks in NIH-3T3 fibroblasts

Sei-1 is a potential oncogene that plays an important role in promoting genomic instability. Double minute chromosomes (DMs) are hallmarks of gene amplification and contribute to tumorigenesis. Defects in the DNA double-strand break (DSB) repairing pathways can lead to gene amplification. To date, the mechanisms governing the formation of DMs induced by Sei-1 are not fully understood. We established DMs induced by Sei-1 in the NIH-3T3 cell line. RNA-sequencing was used to identify key characteristics of differentially expressed genes. Metaphase spreads were used to calculate DM numbers. Immunofluorescence was employed to detect γH2AX foci. Western blot and Akt pathway inhibition experiments were performed to reveal the role of the PI3K/Akt/BRCA1-Abraxas pathway in Sei-1-induced DMs. Luciferase reporter assay was employed to explore the regulatory mechanisms between Sei-1 and BRCA1. DM formation was associated with a deficiency in DSB repair. Based on this finding, activation of the PI3K/Akt/BRCA1-Abraxas pathway was found to increase the DM population with passage in vivo, and inhibition resulted in a reduction of DMs. Apart from this, it was shown for the first time that Sei-1 could directly regulate the expression of BRCA1. Our results suggest that the PI3K/Akt/BRCA1-Abraxas pathway is responsible for the formation of DMs induced by Sei-1.

SEI1 induces genomic instability by inhibiting DNA damage response in ovarian cancer

Previous studies have shown that the oncogene SEI1 is highly expressed in ovarian carcinomas, and promoting genomic instability. However, the molecular mechanism of SEI1 in promoting genomic instability remains unclear. We observed SEI1 overexpression in 30 of 46 cases of ovarian cancer compared to non-tumor tissues and the overexpression of SEI1 was positively associated with the tumor FIGO stage. Our functional studies revealed that overexpression of SEI1 could induce genomic instability and increased DNA strand breaks. In contrast, SEI1 co-localized with γH2AX and phosphorylated ATM and DNAPKcs in the nucleus. Furthermore, we found that overexpression of SEI1 induced translocation of the SEI1 protein from the cytoplasm to the nucleus; ATM and DNAPKcs were associated with the cytoplasm-to-nucleus translocation of SEI1. To further prove the correlation between the DNA damage response (DDR) and SEI1, we knocked down SEI1 expression in SEI1-transfected ovarian cancer cell lines. The expression of DDR proteins was significantly downregulated, and the number of micronuclei was significantly decreased. Together, these results define a new mechanism of SEI1 in the regulation of genomic stability and in the malignant progression of ovarian cancer.