Humanized animals as models of experimental oncology (review)

The humanization of immunodeficient animals allows us to study the growth of xenografts of human malignant tumors and their response to therapeutic effects, taking into account processes in the immune system and tumor zone, which have a significant impact on oncogenesis and the effectiveness of antitumor therapy. Such experimental models are currently considered as the most advanced tool in the development of personalized antitumor treatment. The lines of immunodeficient animals most commonly used for the transplantation of mature and stem human immune cells have been characterized. The main sources of human immune cells when implementing the hu-pbl and hu-cd34+ models, as well as the blt model (as an option to the cd34+ model) are described. The basic procedures necessary for reproducing each model, their modification in adult and newborn animals are outlined as well as the parameters of immunosuppressive radiation exposure, preceding the transplantation of human hematopoietic stem cells. The main results of the humanization of immunodeficient animals and examples of the use of these models for the purposes of fundamental and clinical oncology are described. The main problems of this direction are discussed. The review is based on an analysis of the literature presented in the scopus, web of science, medline, risc and others databases over the past 7 years (over 80 % of literature sources, with more than over 50 % of studies published over the last 3 years).

PCAT6 May Be a Whistler and Checkpoint Target for Precision Therapy in Human Cancers

LncRNAs are involved in the occurrence and progressions of multiple cancers. Emerging evidence has shown that PCAT6, a newly discovered carcinogenic lncRNA, is abnormally elevated in various human malignant tumors. Until now, PCAT6 has been found to sponge various miRNAs to activate the signaling pathways, which further affects tumor cell proliferation, migration, invasion, cycle, apoptosis, radioresistance, and chemoresistance. Moreover, PCAT6 has been shown to exert biological functions beyond ceRNAs. In this review, we summarize the biological characteristics of PCAT6 in a variety of human malignancies and describe the biological mechanisms by which PCAT6 can facilitate tumor progression. Finally, we discuss its diagnostic and prognostic values and clinical applications in various human malignancies.

Gene Amplification and the Extrachromosomal Circular DNA

Oncogene amplification is closely linked to the pathogenesis of a broad spectrum of human malignant tumors. The amplified genes localize either to the extrachromosomal circular DNA, which has been referred to as cytogenetically visible double minutes (DMs), or submicroscopic episome, or to the chromosomal homogeneously staining region (HSR). The extrachromosomal circle from a chromosome arm can initiate gene amplification, resulting in the formation of DMs or HSR, if it had a sequence element required for replication initiation (the replication initiation region/matrix attachment region; the IR/MAR), under a genetic background that permits gene amplification. In this article, the nature, intracellular behavior, generation, and contribution to cancer genome plasticity of such extrachromosomal circles are summarized and discussed by reviewing recent articles on these topics. Such studies are critical in the understanding and treating human cancer, and also for the production of recombinant proteins such as biopharmaceuticals by increasing the recombinant genes in the cells.

MiR-23b-3p Targeting NCAPG Promotes Cell Proliferation and Anti-Apoptosis By Regulating PI3K/AKT Signaling Pathway in Colorectal Cancer

Colorectal cancer (CRC) is one of the major malignancies with poor prognosis. NCAPG is reportedly upregulated in human malignant tumors. However, its clinicopathological and biological significance in CRC are still indistinct. In this investigation, NCAPG was upregulated in human CRC specimens and CRC cells. NCAPG overexpression was positively correlated with clinicopathological characteristics, such as differentiation and tumor size, and was independently associated with poor survival. Consistent with clinical observations, NCAPG significantly promoted tumorigenesis and inhibited apoptosis of CRC cells in vitro and in vivo. Moreover, we found knockdown of NCAPG inhibited proliferation through regulating PI3K/AKT pathway. Furthermore, we showed that NCAPG was a potential target whose expression is negatively modulated by miR-23b-3p. Taken together, the miR-23b-3p/NCAPG/PI3K/AKT axis plays tumorigenic roles in colorectal carcinogenesis and acts as a therapeutic or diagnostic target.

Krüppel-Like Factor 6 Splice Variant 1: An Oncogenic Transcription Factor Involved in the Progression of Multiple Malignant Tumors

Krüppel-like factor 6 (KLF6) is one of the most studied members of the specificity protein/Krüppel-like factor (SP/KLF) transcription factor family. It has a typical zinc finger structure and plays a pivotal role in regulating the biological processes of cells. Recently, it has been considered to play a role in combatting cancer. Krüppel-like factor 6 splice variant 1 (KLF6-SV1), being one of the alternative KLF6 splicing isoforms, participates in tumor occurrence and development and has the potential to become a new target for molecular targeted therapy, although its action mechanism remains to be determined. The purpose of this article is to provide a comprehensive and systematic review of the important role of KLF6-SV1 in human malignant tumors to provide novel insights for oncotherapy.

Long noncoding RNA SNHG1 promotes TERT expression by sponging miR-18b-5p in breast cancer

Background: Long noncoding RNA (lncRNA) small nucleolar RNA host gene 1 (SNHG1) plays a positive role in the progression of human malignant tumors. However, the molecular mechanism of SNHG1 remains elusive in breast cancer. Results: LncRNA SNHG1 was upregulated and had a positive relationship with poor prognosis according to bioinformatics analysis. Silencing SNHG1 inhibited tumorigenesis in breast cancer both in vitro and in vivo. Mechanistically, SNHG1 functioned as a ceRNA to promote TERT expression by sponging miR-18b-5p. Moreover, miR-18b-5p acted as a tumor repressor in breast cancer. Finally, E2F1, a transcription factor, enhanced SNHG1 transcription.Conclusions: Our results provide a comprehensive understanding of the oncogenic mechanism of lncRNA SNHG1 in breast cancer. Importantly, we identified a novel E2F1–SNHG1–miR-18b-5p–TERT axis, which may be a potential therapeutic target for breast cancer.

GSK3 Kinase Inhibitor, CHIR, Suppress Transcription of Tissue Specific POU2F1 Isoform in Burkitt Namalwa Lymphoma Cells

POU2F1 (Oct-1) is a transcription factor, the overexpression of which is found in many human malignant tumors; a significant increase in its level in cells determines the malignant potential of the tumor. POU2F1 is represented in cells by several isoforms that are transcribed from alternative promoters. In Burkitt’s B-cell lymphoma Namalwa, the concentration of tissue-specific isoform Oct-1L is several times higher than in normal B cells. We tested the potential to inhibit the transcription of individual Oct-1 isoforms using the GSK3 kinase inhibitor CHIR, an aminopyrimidine derivative. We have shown that CHIR specifically affects the expression of the tissue-specific isoform Oct-1L, significantly reducing the level of mRNA and Oct-1L protein. However, CHIR does not change the amount of mRNA and protein of the ubiquitous isoform Oct-1A in Namalwa tumor cells. The results obtained show that it is possible to develop a system for selective inhibition of Oct-1 transcription factor isoforms in human cells to suppress drug resistance of tumor cells with a high POU2F1 content.

GFI1-Mediated Upregulation of LINC00675 as a ceRNA Restrains Hepatocellular Carcinoma Metastasis by Sponging miR-942-5p

Hepatocellular carcinoma (HCC) is a common malignant liver tumor worldwide. Tumor recurrence and metastasis contribute to the bad clinical outcome of HCC patients. Substantial studies have displayed lncRNAs modulate various tumorigenic processes of many cancers. Our current work was aimed to investigate the function of LINC00675 in HCC and to recognize the potential interactions between lncRNAs and microRNAs. GFI1 can exhibit a significant role in the progression of human malignant tumors. Firstly, GFI1 was identified using real-time PCR in HCC tissues and cells. In this work, we indicated GFI1 was remarkably reduced in HCC tissues and cells. Meanwhile, GFI1 specifically interacted with the promoter of LINC00675. Up-regulation of LINC00675 obviously repressed the migration and invasion capacity of SMCC-7721 and QGY-7703 cells in vitro. Moreover, decrease of LINC00675 competitively bound to miR-942-5p that contributed to the miRNA-mediated degradation of GFI1, thus facilitated HCC metastasis. The ceRNA function of LINC00675 in HCC cells was assessed and confirmed using RNA immunoprecipitation assay and RNA pull-down assays in our work. Additionally, we proved overexpression of miR-942-5p promoted HCC progression, which was reversed by the up-regulation of GFI1. In summary, LINC00675 might act as a prognostic marker for HCC, which can inhibit HCC development via regulating miR-942-5p and GFI1.

miR-513b-5p inhibits the proliferation and promotes apoptosis of retinoblastoma cells by targeting TRIB1

MicroRNAs are involved in the pathogenesis of various human malignant tumors. This study aims to explore the role of miR-513b-5p in the malignant proliferation of retinoblastoma (RB) cells and its potential molecular mechanisms. The function-gain and function-loss experiments were performed in Weri-RB1 cells using miR-513b-5 mimics and inhibitors. miR-513b-5p mimics inhibited the proliferation and clone formation and promoted apoptosis of Weri-RB1 cells. In contrast, the miR-513b-5p inhibitor promoted the proliferation and clone formation of Weri-RB1 cells and inhibited cell apoptosis. miR-513b-5p can directly bind to the 3′UTR region of TRIB1 mRNA, and inhibit its protein expression. Overexpression of TRIB1 promoted the proliferation and cloning of Weri-RB1 cells but inhibited their apoptosis. The knockdown of TRIB1 inhibited the proliferation and clone formation of Weri-RB1 cells and promoted cell apoptosis. In addition, miR-513b-5p mimics neutralized the effects of TRIB1 overexpression on the proliferation and apoptosis of Weri-RB1 cells. Finally, miR-513b-5p can inhibit the phosphorylation level of AKT, mTOR, and p70, while TRIB1 played the opposite role. miR-513b-5p inhibits the malignant proliferation of Weri-RB1 cells by repressing the expression of TRIB1. miR-513b-5p and TRIB1 may be the biomarkers and/or key targets for clinical diagnosis and treatment of RB.