MiR-125a-5p inhibits EMT of ovarian cancer cells by regulating TAZ/EGFR signaling pathway

CircSHKBP1 regulates colon cancer cell proliferation and apoptosis by targeting miR-125a-5p

BACKGROUND

Colon cancer is a common malignant tumor in clinical practice. It has been reported that circular RNAs (circRNAs) are involved in the occurrence and development of cancer. Among them, circSHKBP1 acts as an oncogene to promote cancer progression. Thus, we hypothesized that circSHKBP1 might be also implicated in the development of colon cancer.

AIM

To explore the role of circSHKBP1 in colon cancer cell proliferation and apoptosis and the possible mechanism involved.

METHODS

Sixty-nine cancer tissues and matched adjacent normal tissues were selected from March 2020 to July 2020 at our hospital. The expression of circSHKBP1 and miR-125a-5p was detected by qRT-PCR. Human colon cancer cells (HT29) cultured in vitro were randomly divided into sh-NC group, sh-circSHKBP1 group, miR-NC group, miR-125a-5p group, sh-circSHKBP1 + anti-miR-NC group, and sh-circSHKBP1 + anti-miR-125a-5p group. MTT assay, colony formation experiment, and flow cytometry were used to detect cell proliferation, colony formation, and apoptosis, respectively. The dual luciferase reporter experiment was used to detect the impact of miR-125a-5p overexpression on the luciferase activity of the wild-type vector wt-circSHKBP1. Western blot was used to detect the protein expression of Bax and Bcl-2.

RESULTS

Compared with adjacent tissues, the expression of circSHKBP1 in colon cancer tissues was increased (P < 0.05), while the expression of miR-125a-5p was decreased (P < 0.05). Cell proliferation inhibition rate, apoptosis rate, and Bax protein level in the sh-circSHKBP1 group were increased (P < 0.05), while the number of cell colonies (P < 0.05) and Bcl-2 protein level were decreased (P < 0.05). Overexpression of miR-125a-5p could reduce the luciferase activity of wt-circSHKBP1 (P < 0.05). Relative to the miR-NC group, miR-125a-5p reduced cell proliferation, increased apoptosis rate and Bax protein level (P < 0.05), decreased the number of cell colonies (P < 0.05), and reduced Bcl-2 protein level (P < 0.05). Compared with the sh-circSHKBP1 + anti-miR-NC group, cell proliferation inhibition rate, apoptosis, and the protein level of Bax in the sh-circSHKBP1 + anti-miR-125a-5p group were decreased (P < 0.05), while the number of cell colonies and Bcl-2 protein level were increased (P < 0.05).

CONCLUSION

Knockdown of circSHKBP1 could inhibit colon cancer cell proliferation and promote apoptosis via up-regulating miR-125a-5p expression.

The Emerging Roles and Therapeutic Implications of Epigenetic Modifications in Ovarian Cancer

Ovarian cancer (OC) is one of the most lethal gynecologic malignancies globally. In spite of positive responses to initial therapy, the overall survival rates of OC patients remain poor due to the development of drug resistance and consequent cancer recurrence. Indeed, intensive studies have been conducted to unravel the molecular mechanisms underlying OC therapeutic resistance. Besides, emerging evidence suggests a crucial role for epigenetic modifications, namely, DNA methylation, histone modifications, and non-coding RNA regulation, in the drug resistance of OC. These epigenetic modifications contribute to chemoresistance through various mechanisms, namely, upregulating the expression of multidrug resistance proteins (MRPs), remodeling of the tumor microenvironment, and deregulated immune response. Therefore, an in-depth understanding of the role of epigenetic mechanisms in clinical therapeutic resistance may improve the outcome of OC patients. In this review, we will discuss the epigenetic regulation of OC drug resistance and propose the potential clinical implications of epigenetic therapies to prevent or reverse OC drug resistance, which may inspire novel treatment options by targeting resistance mechanisms for drug-resistant OC patients.

miR‑125a‑5p reverses epithelial‑mesenchymal transition and restores drug sensitivity by negatively regulating TAFAZZIN signaling in breast cancer

MicroRNA (miR)‑125a‑5p represses tafazzin phospholipid‑lysophospholipid transacylases (TAFAZZIN) expression and inhibits the epithelial‑mesenchymal transition (EMT) of ovarian cancer cells. EMT was found to have a crucial role in the acquisition of chemoresistance. Thus, the present study aimed to determine whether miR‑125a‑5p reverses EMT and restores drug sensitivity by negatively regulating TAFAZZIN in breast cancer. The expression of miR‑125a‑5p/TAFAZZIN and its association with chemotherapy response were determined in tissue samples from patients with breast cancer. Furthermore, the effects of miR‑125a‑5p on breast cancer cells were elucidated using cell proliferation and cell apoptosis assays. Then, the regulatory mechanism of miR‑125a‑5p in breast cancer was investigated by reverse transcription‑quantitative PCR, western blotting, dual‑luciferase reporter and RNA immunoprecipitation assays. The results demonstrated that miR‑125a‑5p inhibited the EMT of MCF‑7/adriamycin (Adr) breast cancer cells, as well as decreased the proliferation and increased the apoptosis of breast cancer cells treated with Adr/docetaxel. In addition, miR‑125a‑5p downregulated the expression levels of TAFAZZIN, Transglutaminase 2, phosphorylated‑AKT, N‑cadherin, vimentin and proliferating cell nuclear antigen, and significantly increased those of E‑cadherin, cleaved caspase-3 and Bax in MCF7/Adr cells. Similar results were obtained with small interfering RNA‑TAFAZZIN. Moreover, TAFAZZIN was identified as a direct target of miR‑125a‑5p in MCF7/Adr breast cancer cells. In addition, increased miR‑125a‑5p expression was observed in breast tumors from patients exhibiting a chemotherapy response, and TAFAZZIN mRNA expression was elevated in patients with no chemotherapy response. Hence, miR‑125a‑5p expression was negatively correlated with TAFAZZIN mRNA expression in breast cancer tissues. All these data suggested that miR‑125a‑5p reverses EMT and restores drug sensitivity by negatively regulating TAFAZZIN in breast cancer and, therefore, has potential as a novel therapeutic target for this disease.

The Impact of Non-coding RNAs in the Epithelial to Mesenchymal Transition

Epithelial to mesenchymal transition (EMT) is a course of action that enables a polarized epithelial cell to undertake numerous biochemical alterations that allow it to adopt features of mesenchymal cells such as high migratory ability, invasive properties, resistance to apoptosis, and importantly higher-order formation of extracellular matrix elements. EMT has important roles in implantation and gastrulation of the embryo, inflammatory reactions and fibrosis, and transformation of cancer cells, their invasiveness and metastatic ability. Regarding the importance of EMT in the invasive progression of cancer, this process has been well studies in in this context. Non-coding RNAs (ncRNAs) have been shown to exert critical function in the regulation of cellular processes that are involved in the EMT. These processes include regulation of some transcription factors namely SNAI1 and SNAI2, ZEB1 and ZEB2, Twist, and E12/E47, modulation of chromatin configuration, alternative splicing, and protein stability and subcellular location of proteins. In the present paper, we describe the influence of ncRNAs including microRNAs and long non-coding RNAs in the EMT process and their application as biomarkers for this process and cancer progression and their potential as therapeutic targets.

CircRNA ARFGEF1 functions as a ceRNA to promote oncogenic KSHV-encoded viral interferon regulatory factor induction of cell invasion and angiogenesis by upregulating glutaredoxin 3

Circular RNAs (circRNAs) are novel single-stranded noncoding RNAs that can decoy other RNAs to inhibit their functions. Kaposi’s sarcoma (KS), caused by oncogenic Kaposi’s sarcoma-associated herpesvirus (KSHV), is a highly angiogenic and invasive vascular tumor of endothelial origin commonly found in AIDS patients. We have recently shown that KSHV-encoded viral interferon regulatory factor 1 (vIRF1) induces cell invasion, angiogenesis and cellular transformation; however, the role of circRNAs is largely unknown in the context of KSHV vIRF1. Herein, transcriptome analysis identified 22 differentially expressed cellular circRNAs regulated by vIRF1 in an endothelial cell line. Among them, circARFGEF1 was the highest upregulated circRNA. Mechanistically, vIRF1 induced circARFGEF1 transcription by binding to transcription factor lymphoid enhancer binding factor 1 (Lef1). Importantly, upregulation of circARFGEF1 was required for vIRF1-induced cell motility, proliferation and in vivo angiogenesis. circARFGEF1 functioned as a competing endogenous RNAs (ceRNAs) by binding to and inducing degradation of miR-125a-3p. Mass spectrometry analysis demonstrated that glutaredoxin 3 (GLRX3) was a direct target of miR-125a-3p. Knockdown of GLRX3 impaired cell motility, proliferation and angiogenesis induced by vIRF1. Taken together, vIRF1 transcriptionally activates circARFGEF1, potentially by binding to Lef1, to promote cell oncogenic phenotypes via inhibiting miR-125a-3p and inducing GLRX3. These findings define a novel mechanism responsible for vIRF1-induced oncogenesis and establish the scientific basis for targeting these molecules for treating KSHV-associated cancers.

Kaposi’s sarcoma-associated herpesvirus (KSHV) is the etiological agent of Kaposi’s sarcoma (KS), which frequently occurs in people with AIDS. We and others had proved that KSHV-encoded viral interferon regulatory factor 1 (vIRF1) was crucial in the pathogenesis of KSHV-induced cancers. KSHV genome transcribes viral circular RNAs (circRNAs), however, the role of cellular circRNAs in vIRF1-induced tumorigenesis remains unknown. CircRNAs serves as competitive endogenous RNAs (ceRNAs) of miRNAs, thus regulating miRNA-mRNA network to influence mRNA stability and protein expression. Here we found that vIRF1 binds to the promoter of the parental gene ARFGEF1 and activate circARFGEF1 transcription through interaction with transcription factor lymphoid enhancer binding factor 1 (Lef1). CircARFGEF1 functioned as a ceRNA by binding to and inducing degradation of miR-125a-3p, thereby abrogating the inhibition effect of this miRNA on its direct targeting of GLRX3. Significantly, circARFGEF1/miR-125a-3p/GLRX3 axis was required for vIRF1 induction of cell motility, proliferation and in vivo angiogenesis. In summary, our study describes a novel mechanism of KSHV-induced oncogenesis by hijacking host circRNAs through a viral oncogene.

Propofol‑induced miR‑125a‑5p inhibits the proliferation and metastasis of ovarian cancer by suppressing LIN28B

Propofol, a commonly used intravenous anesthetic agent during surgery, has relatively widespread pharmacological actions. Previous studies have reported that propofol may act as an antitumor drug in several cancer types, such as pancreatic cancer, lung cancer and gastric cancer. However, the underlying mechanism in ovarian cancer remain unknown. Therefore, the present study investigated the pharmacological effect of propofol on microRNAs (miRNAs) in ovarian cancer treatment. Propofol (1, 5 or 10 µg/ml) was used to treat A2780 and SKOV3 ovarian cancer cells for 1, 2, 3, 4 or 5 days. The MTT assay was used to detect cell viability, while wound healing and Transwell assays were utilized to assess the invasive and migratory abilities. The bioinformatics prediction approach identified differentially expressed miRNAs (miRs) that were used in Gene Ontology, Gene Set Enrichment Analysis and Kyoto Encyclopedia of Genes and Genomes analyses. The expression levels of miR‑125a‑5p and lin‑28 homolog B (LIN28B) were evaluated by reverse transcription‑quantitative PCR (RT‑qPCR). A luciferase assay was performed to identify the relationship between miR‑125a‑5p and LIN28B. Western blotting was conducted to measure the protein expression of LIN28B. It was demonstrated that propofol significantly upregulated miR‑125a‑5p to exert its antitumor activity. RT‑qPCR results suggested that propofol could upregulate miR‑125a‑5p and LIN28B expression levels in ovarian cancer cell lines. Western blot analysis also indicated that propofol could enhance the expression of LIN28B in ovarian cancer cell lines. The luciferase assay identified that miR‑125a‑5p could directly inhibit the expression of LIN28B to suppress proliferation and metastasis in ovarian cancer. In conclusion, these results suggested that propofol inhibited ovarian cancer proliferation and metastasis by enhancing miR‑125a‑5p, which targets LIN28B.

Flaming the fight against cancer cells: the role of microRNA-93

There have been attempts to develop novel anti-tumor drugs in cancer therapy. Although satisfying results have been observed at a consequence of application of chemotherapeutic agents, the cancer cells are capable of making resistance into these agents. This has forced scientists into genetic manipulation as genetic alterations are responsible for generation of a high number of cancer cells. MicroRNAs (miRs) are endogenous, short non-coding RNAs that affect target genes at the post-transcriptional level. Increasing evidence reveals the potential role of miRs in regulation of biological processes including angiogenesis, metabolism, cell proliferation, cell division, and cell differentiation. Abnormal expression of miRs is associated with development of a number of pathologic events, particularly cancer. MiR-93 plays a significant role in both physiological and pathological mechanisms. At the present review, we show how this miR dually affects the proliferation and invasion of cancer cells. Besides, we elucidate the oncogenesis or oncosuppressor function of miR-93.

Association of the Epithelial-Mesenchymal Transition (EMT) with Cisplatin Resistance

Therapy resistance is a characteristic of cancer cells that significantly reduces the effectiveness of drugs. Despite the popularity of cisplatin (CP) as a chemotherapeutic agent, which is widely used in the treatment of various types of cancer, resistance of cancer cells to CP chemotherapy has been extensively observed. Among various reported mechanism(s), the epithelial–mesenchymal transition (EMT) process can significantly contribute to chemoresistance by converting the motionless epithelial cells into mobile mesenchymal cells and altering cell–cell adhesion as well as the cellular extracellular matrix, leading to invasion of tumor cells. By analyzing the impact of the different molecular pathways such as microRNAs, long non-coding RNAs, nuclear factor-κB (NF-ĸB), phosphoinositide 3-kinase-related protein kinase (PI3K)/Akt, mammalian target rapamycin (mTOR), and Wnt, which play an important role in resistance exhibited to CP therapy, we first give an introduction about the EMT mechanism and its role in drug resistance. We then focus specifically on the molecular pathways involved in drug resistance and the pharmacological strategies that can be used to mitigate this resistance. Overall, we highlight the various targeted signaling pathways that could be considered in future studies to pave the way for the inhibition of EMT-mediated resistance displayed by tumor cells in response to CP exposure.