Up-Regulation of LINC00665 Facilitates the Malignant Progression of Prostate Cancer by Epigenetically Silencing KLF2 Through EZH2 and LSD1

LINC00665 target let-7i/HMGA1 promotes the proliferation and invasion of hepatoma cells

OBJECTIVES

Our group previously found that LINC00665 was upregulated in hepatocellular carcinoma (HCC) tissues through database analysis; however, the potential molecular mechanism of LINC00665 in HCC progression still needs further study.

METHODS

qRTPCR was performed to determine the differential expression of LINC00665 and let-7i in HCC cells. Dual-luciferase reporter assays were performed to analyze the interaction of LINC00665 and let-7i. CCK-8 assays, scratch assays, Transwell invasion assays, qRTPCR and western blotting were performed to determine the regulatory mechanism of LINC00665/let-7i/HMGA1 in HCC cells.

RESULTS

LINC00665 was upregulated in HCC cells compared with normal hepatocytes. A potential binding site between LINC00665 and let-7i was confirmed by dual-luciferase reporter assay. In HCC cells, inhibition of LINC00665 significantly reduced cell proliferation, migration and invasion ability via the let-7i/HMGA1 signaling axis.

CONCLUSION

LINC00665 promotes the proliferation and invasion of HCC cells via the let-7i/HMGA1 signaling axis.

Mechanism of tumor-derived extracellular vesicles in prostatic cancer progression through the circFMN2/KLF2/RNF128 axis

Circular RNAs (circRNAs) are a major type of cargos encapsulated in extracellular vesicles (EVs) and regulate the progression of prostatic cancer (PC). This study was conducted to explore the role of tumor-derived EVs in PC cell proliferation, invasion, and migration via shuttle of circRNA formin 2 (circFMN2). RT-qPCR or Western blot assay showed that circFMN2 was upregulated while KLF2 and RNF128 were downregulated in PC tissues and cells. EVs were separated from PC cells and characterized and its internalization in PC cells was examined, which suggested that PC-EVs mediated the shuttle of circFMN2 to upregulate circFMN2 expression in PC cells. PC cell functions were determined by cell counting kit-8, colony formation and Transwell assays, which suggested that PC-EVs fueled the proliferation, invasion, and migration of PC cells. At cellular level, PC-EVs mediated the shuttle of circFMN2 to upregulate circFMN2 expression in PC cells, and circFMN2 binding to HuR decreased the HuR-KLF2 interaction and repressed KLF2 expression, which further reduced the KLF2-RNF128 promoter binding and repressed RNF128 transcription. Overexpression of KLF2/RNF128 ablated the effects of PC-EVs on the proliferation, invasion, and migration of PC cells. The xenograft tumor models and lung/liver metastasis models were established and revealed that PC-EVs accelerated tumorigenesis and metastasis in vivo via delivery of circFMN2 and repression of KLF2/RNF128.

Prognostic and clinicopathological values of LINC00665 in cancers: a systematic review and China population-based meta-analysis

BACKGROUND

Recent studies have uncovered that the aberrant expression of LINC00665 contributes to the malignant pathological process of various cancers and is closely related to the unfavorable prognosis of patients with cancer. However, a systematic analysis of the prognostic and clinicopathologic values of LINC00665 in cancers has not been conducted.

OBJECTIVE

We aim to clarify the association of LINC00665 expression with patient survival and clinicopathologic phenotypes in cancers.

METHODS

An electronic search of PubMed, Embase and Web of Science was performed to select eligible literature. Pooled hazard ratio (HR) and odds ratio (OR) were calculated to assess the clinical importance of LINC00665. The fixed-effects model was used to analyze the combined HR values and 95% CI when the studies had no significant heterogeneity (P > 0.1 for the Chi-square test or I2 < 50%). Begg's test and sensitivity analysis were also conducted. This study was registered in The International Prospective Register of Systematic Reviews (PROSPERO registration number: CRD42021290123).

RESULTS

A total of 710 patients from 10 eligible studies were enrolled in this meta-analysis, which was based on China population. The pooled results of this analysis revealed that high-level expression of LINC00665 was notably correlated with poor overall survival (HR = 2.08, 95% CI = 1.57-2.75) and recurrence-free survival (HR = 2.49, 95% CI = 1.63-3.80) in human cancers. Elevated LINC00665 expression was also correlated with more advanced clinical stage, earlier lymph node metastasis, lower tumor differentiation, earlier distant metastasis and larger tumor size.

CONCLUSION

LINC00665 expression was critically related to the cancer prognosis, which has important prognostic implications for clinical prediction.

Blockage of MDM2-mediated p53 ubiquitination by yuanhuacine restrains the carcinogenesis of prostate carcinoma cells by suppressing LncRNA LINC00665

Prostate cancer (PCa) is a challenging issue for men's health worldwide due to its uncontrolled proliferation and high metastatic potential. Increasing evidence has supported plant extracts and natural plant derivatives as promising antitumor therapy with less toxic side effects. Yuanhuacine is an active component isolated from Daphne genkwa and can effectively suppress the tumorigenesis of several cancers. However, its role in PCa remains unclear. In this study, yuanhuacine dose-dependently inhibited the proliferation and induced apoptosis of PCa cells. Moreover, yuanhuacine also restrained the invasion and migration of PCa cells. Mechanically, yuanhuacine decreased the ubiquitination and degradation of p53 protein, and ultimately increased p53 levels, which was regulated by inhibiting the phosphorylation and total protein levels of mouse double minute 2 (MDM2). Moreover, elevation of MDM2 reversed the suppressive efficacy of yuanhuacine in PCa cell viability, invasion, and migration. The network pharmacologic and bioinformatics analysis confirmed that MDM2 might be a common target of D. genkwa and LINC00665. Furthermore, yuanhuacine inhibited LINC00665 expression. Upregulation of LINC00665 reversed yuanhuacine-mediated inhibition in MDM2 protein expression and suppressed p53 levels by enhancing its ubiquitination in yuanhuacine-treated cells. Importantly, the inhibitory effects of yuanhuacine on cell viability and metastatic potential were offset after LINC00665 elevation. Together, the current findings highlight that yuanhuacine may possess tumor-suppressive efficacy by inhibiting LINC00665-mediated MDM2/p53 ubiquitination signaling. Therefore, this study indicates that yuanhuacine may be a promising candidate for the treatment of PCa.

A Concise Review on Dysregulation of LINC00665 in Cancers

Long Intergenic Non-Protein Coding RNA 665 (LINC00665) is an RNA gene located on the minus strand of chromosome 19. This lncRNA acts as a competing endogenous RNA for miR-4458, miR-379-5p, miR-551b-5p, miR-3619-5p, miR-424-5p, miR-9-5p, miR-214-3p, miR-126-5p, miR-149-3p, miR-379-5p, miR-665, miR-34a-5p, miR-186-5p, miR-138-5p, miR-181c-5p, miR-98, miR-195-5p, miR-224-5p, miR-3619, miR-708, miR-101, miR-1224-5p, miR-34a-5p, and miR-142-5p. Via influencing expression of these miRNAs, it can enhance expression of a number of oncogenes. Moreover, LINC00665 can influence activity of Wnt/β-Catenin, TGF-β, MAPK1, NF-κB, ERK, and PI3K/AKT signaling. Function of this lncRNA has been assessed through gain-of-function tests and/or loss-of-function studies. Furthermore, diverse research groups have evaluated its expression levels in tissue samples using microarray and RT-qPCR techniques. In this manuscript, we have summarized the results of these studies and categorized them in three sections, i.e., cell line studies, animal studies, and investigations in clinical samples.

Bioinformatics analysis of KLF2 as a potential prognostic factor in ccRCC and association with epithelial‑mesenchymal transition

Clear cell renal cell carcinoma (ccRCC) is a primary pathological subtype of RCC and has poor clinical outcome. Krüppel-like factors (KLFs), which are zinc-finger proteins, may be involved in ccRCC development and progression. KLFs belong to the zinc-finger family of DNA-binding transcription factors and regulate transcription of downstream target genes. KLFs are involved in cancer development. The present study aimed to investigate the role of KLFs in ccRCC prognosis. The Cancer Genome Atlas database and multifactorial analysis showed that KLFs were widely expressed in pan-cancers and KLF2 was an independent protective factor for ccRCC prognosis. Patients with low KLF2 expression had a low survival probability and expression of KLF2 was downregulated in patients with ccRCC with high pathological grade (II + III vs. I). In addition, western blot and reverse transcription-quantitative PCR revealed that KLF2 was expressed at low levels in ccRCC cell lines and overexpression of KLF2 inhibited cell migration. In addition, KLF2 expression was negatively correlated with methylation. KLF2 expression was elevated following treatment of ccRCC cells with DNA methyltransferase inhibitor. A prognostic risk index prediction model was constructed based on multiple Cox regression. The receiver operating characteristic curve was 0.780 (area under curve >0.5). Furthermore, Gene Ontology enrichment analysis showed that ‘cell adhesion’ and ‘junction’ were negatively correlated with KLF2 and that high-risk group exhibited significantly activated ‘epithelial-mesenchymal transition’. Western blot analysis showed that overexpression of KLF2 increased expression of E-cadherin, while decreasing levels of N-cadherin and vimentin. The present study highlighted the role of KLFs in ccRCC prognosis prediction and provides a research base for the search of validated prognostic biological markers for ccRCC.

The Biological and Molecular Function of LINC00665 in Human Cancers

Long non-coding RNAs (lncRNAs) are more than 200 nucleotides in length and are implicated in the development of human cancers, without protein-coding function. Mounting evidence indicates that cancer initiation and progression are triggered by lncRNA dysregulation. Recently, a growing number of studies have found that LINC00665, a long intergenic non-protein coding RNA, may be associated with various cancers, including gastrointestinal tumors, gynecological tumors, and respiratory neoplasms. LINC00665 was reported to be significantly dysregulated in cancers and has an important clinical association. It participates in cell proliferation, migration, invasion, and apoptosis through different biological pathways. In this review, we summarize the current findings on LINC00665, including its biological roles and molecular mechanisms in various cancers. LINC00665 may be a potential prognostic biomarker and novel therapeutic target for cancers.

LINC00665: An Emerging Biomarker for Cancer Diagnostics and Therapeutics

Long intergenic noncoding RNA 00665 (LINC00665) is located on human chromosome 19q13.12. LINC00665 was upregulated in eighteen cancers and downregulated in two cancers. LINC00665 not only inhibits 25 miRNAs but also directly affects the stability of ten protein-coding genes. Notably, LINC00665 also encodes a micro-peptide CIP2A-BP that promotes triple-negative breast cancer progression. LINC00665 can participate in five signaling pathways to regulate cancer progression, including the Wnt/β-catenin signaling pathway, TGF-β signaling pathway, NF-κB signaling pathway, PI3K/AKT signaling pathway, and MAPK signaling pathway. Aberrant expression of LINC00665 in breast cancer, gastric cancer, and hepatocellular carcinoma can be used for disease diagnosis. In addition, aberrant expression of LINC00665 is closely associated with clinicopathological features and poor prognosis of various cancers. LINC00665 is closely associated with the effects of anticancer drugs, including gefitinib and cisplatin in non-small cell lung cancer, gemcitabine in cholangiocarcinoma, and cisplatin-paclitaxel in breast cancer. This work systematically summarizes the diagnostic and prognostic values of LINC00665 in various tumors, and comprehensively analyzes the molecular regulatory mechanism related to LINC00665, which is expected to provide clear guidance for future research.

The Emerging Roles of LINC00665 in Human Cancers

Long non-coding RNAs (lncRNAs) are non-coding RNAs that have more than 200 nucleotides and can participate in the regulation of gene expression in various ways. An increasing number of studies have shown that the dysregulated expression of lncRNAs is related to the occurrence and progression of human cancers. LINC00665 is a novel lncRNA, which is abnormally expressed in various human cancers, such as lung cancer, breast cancer, prostate cancer, and glioma. LINC00665 functions in many biological processes of tumor cells, such as cell proliferation, migration, invasion, angiogenesis, and metabolism, and is related to the clinicopathological characteristics of cancer patients. LINC00665 can play biological functions as a ceRNA, directly binding and interacting with proteins, and as an upstream molecule regulating multiple signaling pathways. In this review, we comprehensively summarize the expression level, function, and molecular mechanisms of LINC00665 in different human cancers and emphasize that LINC00665 is a promising new diagnostic, prognostic biomarker, and therapeutic target.

Relation among EGFL7, ITGB3, and KLF2 and their clinical implication in multiple myeloma patients: a prospective study

Objective

We aimed to investigate the relationship among epidermal growth factor–like protein-7 (EGFL7), integrin subunit beta 3 (ITGB3), and Kruppel-like factor 2 (KLF2) expressions and their clinical implication in multiple myeloma (MM).

Methods

This prospective study enrolled 72 de novo symptomatic MM patients and 30 controls, and then collected their bone marrow plasma cell samples. Subsequently, the EGFL7, ITGB3, and KLF2 expressions were carried out by reverse transcription quantitative polymerase chain reaction.

Results

EGFL7, ITGB3, and KLF2 expressions were increased in MM patients compared to controls. Besides, EGFL7, ITGB3, and KLF2 inter-correlated with each other in MM patients but not in controls. In MM patients, EGFL7 and ITGB3 (but not KLF2) expressions were positively correlated with ISS stage, while ITGB3 and KLF2 (but not EGFL7) expressions were correlated with increased R-ISS stage. Interestingly, ITGB3 and KLF2 were decreased in induction-treatment complete remission (CR) MM patients compared to non-CR MM patients, while EGFL7 only showed a trend but without statistical significance. Furthermore, ITGB3 high expression was correlated with worse progression-free survival (PFS) and overall survival (OS), while EGFL7 and KLF2 high expressions only associated with pejorative PFS but not OS.

Conclusion

EGFL7, ITGB3, and KLF2 may serve as potential prognostic indicators in MM patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11845-021-02781-2.