A role for miR-34 in colon cancer stem cell homeostasis

AK, Shaker OG, El-Tahlawi SM, Sabri A, Yaseen SM. Molecular Signature of miR-34a/NEAT-1/p53 Axis in Mycosis Fungoides

Background

Mycosis fungoides (MF) is a type of cutaneous T-cell lymphoma where red rash exists on the skin. Understanding the role of miRNAs and ncRNAs in p53-response has become an open discussion, as they can regulate p53 or its downstream targets, and ncRNAs themselves.

Objectives

To evaluate the serum levels of NEAT-1, miR-34a, and p53 in MF patients and its relation to healthy controls to indicate whether it has a potential role in the pathogenesis of the disease. Subjects and Methods. This prospective case-control study was carried out on 75 subjects subdivided into two groups, 35 MF patients (stages 1 and II) and 40 matched healthy controls. Their clinical investigations and serum biomarkers (NEAT-1, miR-34a, and p53) were measured.

Results

There were significant elevations in the expression levels of both NEAT-1 (5.10 ± 1.16) and p53 (277.28 ± 62.02) in the serum of MF patients in comparison with controls (1.01 ± 0.031) and (194.29 ± 16.039), respectively, while the level of miR-34a tends to decrease in MF patients (0.24 ± 0.15). There are no significant difference between MF stages and the level of miR-34a, while in NEAT-1 and p53, there are significant differences with p value <0.05 between the stages and the biomarkers. There is a positive correlation between the %BSA and miR-34a and a slightly positive correlation between NEAT-1 and P53 with (r = 0.353, p=0.037) and (r = 0112, p=0.05), respectively. There were also negative correlations between disease duration and NEAT-1 with (r = -0.341, p=0.045) and between B2 microglobulin level and p53 (r = -0.373, p=0.027).

Conclusion

The combination of miR-34a, NEAT-1, and p53 may be considered as potential biomarkers that play an active role in the disease process of MF for helping in its early diagnosis and stage identification as well.

miR-34a inhibits melanoma growth by targeting ZEB1

Melanoma is a highly lethal cutaneous cancer with the tendency for early invasion and metastasis. Integrated miRNA transcriptome sequence analysis of human melanoma tumors and adjacent control tissues identified 17 miRNAs differentially expressed in melanoma tissues: let-7a-5p, let-7b-5p, let-7c, miR-374a-3p, miR-100-5p, miR-7, miR-195, miR-1908, miR-214, miR-221, miR-199a-5p, miR-21, miR-18, miR-34a, miR-199a-3p, miR-92a and miR-106b. Among these, miR-34a was most significantly down-regulated in melanoma tissues, and its expression correlated with TNM melanoma stage. miR-34a overexpression inhibited expression and activity of the transcription factor ZEB1, resulting in decreased proliferation and migration of melanoma cells. Moreover, miR-34a overexpression inhibited ZEB1 expression and melanoma tumor growth in vivo, in a melanoma nude mouse model. Together, these findings demonstrate that miR-34a inhibits melanoma growth by targeting the proto-oncogene ZEB1 and suggest the miR-34a -ZEB1 axis may serve as a novel target for melanoma treatment.

The P53/microRNA network: A potential tumor suppressor with a role in anticancer therapy

MicroRNAs (miRNAs) are endogenous and small non-coding RNAs that have been identified as mediators of tumor suppression as well as stress responses mediated by p53 suppressors. MiRNAs may act as tumor suppressors under certain conditions. MiRNAs regulated by p53 may control the expression of processes such as cell cycle progression, cell survival, and angiogenesis. P53 activity and expression are also controlled by miRNA; consequently alterations in the p53-miRNA network may be essential for tumor initiation and progression. Future studies on the p53-miRNA network presumably would find it helpful in diagnostic and therapeutic approaches or as tools for various cancers.

Cell Cycle Regulation of Stem Cells by MicroRNAs

MicroRNAs (miRNAs) are a class of small non-coding RNA molecules involved in the regulation of gene expression. They are involved in the fine-tuning of fundamental biological processes such as proliferation, differentiation, survival and apoptosis in many cell types. Emerging evidence suggests that miRNAs regulate critical pathways involved in stem cell function. Several miRNAs have been suggested to target transcripts that directly or indirectly coordinate the cell cycle progression of stem cells. Moreover, previous studies have shown that altered expression levels of miRNAs can contribute to pathological conditions, such as cancer, due to the loss of cell cycle regulation. However, the precise mechanism underlying miRNA-mediated regulation of cell cycle in stem cells is still incompletely understood. In this review, we discuss current knowledge of miRNAs regulatory role in cell cycle progression of stem cells. We describe how specific miRNAs may control cell cycle associated molecules and checkpoints in embryonic, somatic and cancer stem cells. We further outline how these miRNAs could be regulated to influence cell cycle progression in stem cells as a potential clinical application.

miR-665 targets c-MYC and HDAC8 to inhibit murine neuroblastoma cell growth

Neuroblastoma is a common tumor of the peripheral nervous system in children. Highly aggressive MYC-driven neuroblastoma is defined by increased c-MYC and/or MYCN expression. This study employed a mouse neuroblastoma cell model to assess the role of miR-665 in tumorigenesis. We found that miR-665 suppresses mRNAs, targeting c-MYC and HDAC8, which are involved in neuroblastoma tumorigenesis. N6,2'-O-dibutyryladenosine 3':5'cyclic monophosphate (Bt2cAMP) inhibited neuroblastoma cell growth by inhibiting c-MYC and HDAC8 expression and activating caspase 3. Bt2cAMP also upregulated miR-665, and miR665 transfection mimicked the effects of Bt2cAMP, including reduced c-MYC and HDAC8 expression, increased caspase 3 activation, and reduced neuroblastoma cell growth. As compared to untreated cells, Bt2cAMP increased the number of cells in G1 phase by 50% and the number in G2-M phase by 5%, while the number of cells in S phase was reduced 2.8-fold. Similarly, miR-665 transfection increased the number of cells in G1 phase by 16% and the number in G2M phase by 2%, and decreased the cells in S-phase by 18%. These findings indicate miR-665 suppresses neuroblastoma tumorigenesis by inhibiting c-MYC and HDAC8 expression and suggest miR-665 has potential as an anti-neuroblastoma therapeutic.

miR-34 inhibits growth and promotes apoptosis of osteosarcoma in nude mice through targetly regulating TGIF2 expression

miR-34 was reported to be involved in multiple tumors occurrence and development. The aim of the present study was to explore the impact of miR-34 on osteosarcoma and related mechanisms. Tumor tissues and non-tumor tissues of 34 patients with osteosarcoma were collected. qRT-PCR detection revealed that miR-34 was significantly down-regulated in tumor tissues (P<0.05). hFOB 1.19 and MG-63 cells were cultured. qRT-PCR detection showed that miR-34 was also significantly down-regulated in MG-63 cells (P<0.05). After transfection by miR-34 mimics, MG-63 cells proliferation in nude mice was significantly impaired (P<0.05), and percentage of apoptosis as well as caspase-3 positive cells proportion of osteosarcoma tissue in nude mice was markly increased (P<0.05). Western blot and immunofluorescence results also demonstrated that TGIF2 relative expression and TGIF2 positive cells proportion were both dramatically decreased (P<0.05). By luciferase reporter assay, we found that TGIF2 was the target gene of miR-34. After transfected by TGIF2 overexpression vector or co-transfected by miR-34 mimics and TGIF2 overexpression vector, we observed that, compared with blank group, tumor volume was significantly increased and apoptotic cells as well as caspase-3 positive cells proportion was obviously decreased in TGIF2 group (P<0.05), while no significant difference was found in these indicators between blank group and TGIF2 + mimics group. We concluded that miR-34 inhibited growth and promoted apoptosis of osteosarcoma in nude mice through targetting regulated TGIF2 expression.

Senescence-Associated MicroRNAs

Senescent cells arise as a consequence of cellular damage and can have either a detrimental or advantageous impact on tissues and organs depending on the specific cell type and metabolic state. As senescent cells accumulate in tissues with advancing age, they have been implicated in many age-related declines and diseases. The major facets of senescence include two pathways responsible for establishing and maintaining a senescence program, p53/CDKN1A(p21) and CDKN2A(p16)/RB, as well as the senescence-associated secretory phenotype. Numerous MicroRNAs influence senescence by modulating the abundance of key senescence regulatory proteins, generally by lowering the stability and/or translation of mRNAs that encode such factors. Accordingly, understanding the molecular mechanisms by which MicroRNAs influence senescence will enable diagnostic and therapeutic opportunities directed at senescent cells. Here, we review senescence-associated (SA)-MicroRNAs and discuss their implications in senescence-relevant pathologies.