The role of Lin28A and Lin28B in cancer beyond Let-7.

Lin28A and Lin28B are paralogous RNA-binding proteins that play fundamental roles in development and cancer by regulating the microRNA family of tumor suppressor Let-7. Although Lin28A and Lin28B share some functional similarities with Let-7 inhibitors, they also have distinct expression patterns and biological functions. Increasing evidence indicates that Lin28A and Lin28B differentially impact cancer stem cell properties, epithelial-mesenchymal transition, metabolic reprogramming, and other hallmarks of cancer. Therefore, it is important to understand the overexpression of Lin28A and Lin28B paralogs in specific cancer contexts. In this review, we summarize the main similarities and differences between Lin28A and Lin28B, their implications in different cellular processes, and their role in different types of cancer. In addition, we provide evidence of other specific targets of each lin28 paralog, as well as the lncRNAs and miRNAs that promote or inhibit its expression, and how this impacts cancer development and progression.

Maternal expression of miR-let-7d-3p and miR-451a during gestation influences the neuropsychomotor development of 90 days old babies: "Pregnancy care, healthy baby" study.

INTRODUCTION: Studies on maternal microRNA expression have emerged to better understand regulatory mechanisms during the gestational period, since microRNA expression has been associated with pregnancy disorders. OBJECTIVES: This study aims to investigate the association between the expression of the maternal microRNAs miR-let-7d-3p and miR-451a during the second gestational trimester and neuropsychomotor development at 90 days of life of infants. METHODS: This is a case-control study nested within a cohort, with the groups being divided into dyads in which pregnant women presented Major Depressive Episode (MDE) (n = 64), these being the cases, and their respective controls (no MDE; n = 64). The Bayley Scale III was used to assess the outcome of child development, and MDE was assessed through the Mini International Neuropsychiatric Interview Plus. The analysis of miR-let-7d-3p and miR-451a was done via serum from the pregnant women, utilizing the qRT-PCR (n = 128). RESULTS: The results indicated a negative association between expression levels of miR-451a (ß -3.3 CI95% -6.4;-0.3) and a positive associated of the miR-let-7d-3p with the cognitive development domain (ß 1.7 CI95% 0.1; 3.0), and a positive association between expression of miR-let-7d-3p with motor development of the infants (ß 1.6 CI95% 0.3; 2.9). CONCLUSION: This is a pioneering study on the topic that indicates a biological interrelationship between the miRNAs miR-let-7d-3p and miR-451a evaluated during the pregnancy and the motor and cognitive domains of infant development at 90 days postpartum.

let-7b-5p suppresses the proliferation and migration of pulmonary artery smooth muscle cells via down-regulating IGF1.

OBJECTIVES: Some previous studies indicated that the excessive proliferation and migration of Pulmonary Artery Smooth Muscle Cells (PASMCs) could be observed in pulmonary artery intima after Pulmonary Embolism (PE) occurred. In addition, recent studies identified some miRNAs that are differentially expressed in the blood of PE patients, which might be used as a diagnostic biomarker for PE, including let-7a-5p, let-7b-5p, and miR-150-5p. Hence, the authors sought to explore the effects of let-7b-5p in PASMC proliferation and migration and the corresponding regulatory mechanism. METHODS: Platelet-Derived Growth Factor (PDGF) was utilized to induce the hyper-proliferation model in PASMCs. The mRNA and protein expression levels were detected by RT-qPCR and western blot, respectively. The proliferation of PASMCs was evaluated by the detection of PCNA expression, as well as CCK-8 and Edu assays. Wound healing and Transwell assays were exploited to assess the migration ability of PASMCs. The targets of let-7b-5p were predicted based on two bioinformatics online tools. Dual-luciferase and Ago2 pull-down assays were applied to confirm the interaction between let-7b-5p and IGF1. RESULTS: 40 ng/mL PDGF was selected as the optimal concentration to induce PASMCs. let-7b-5p mimics suppressed the proliferation and migration of PDGF-induced PASMCs, while let-7b-5p inhibitor led to the opposite result. In further mechanism exploration, IGF1 was predicted and confirmed as the direct target gene of let-7b-5p. The promotion role of IGF1 overexpression on the proliferation and migration of PDGF-induced PASMCs was dramatically countered by let-7b-5p mimics. CONCLUSION: let-7b-5p prohibits the proliferation and migration of PDGF-induced PASMCs by modulating IGF1.

Study on the mechanism of let-7a-5p in regulating the proliferation in cervical cancer cells.

PURPOSE: To explore the regulatory effect of let-7a-5p/TGFBR1/Smad3 on the proliferation activity of cervical cancer cells. METHODS: The difference in let-7a-5p expression between normal people and patients with cervical cancer was detected by miREIA assay. The differences of let-7a-5p expression between cervical cancer cell line C33a and adjacent normal epithelial cell line HUCEC were determined by qRT-PCR. RESULTS: miREIA result showed that let-7a-5p concentrations were 178.5 ± 24.3 µg/L in healthy individuals and 106.1 ± 14.8 µg/L in cervical cancer patients (P = 0.0002). qRT-PCR showed that let-7a-5p in cervical cancer tissue (0.57 ± 0.03) was lower than that in adjacent normal tissue (0.84 ± 0.04, P = 0.0107). Compared with normal cervical epithelial cells (HUCEC), the expression of let-7a-5p was lower in cervical cancer cells (C33a, Hela, P = 0.0001). The results of CCK-8 and EDU detection showed that activation of let-7a-5p inhibited the proliferation of C33a (P = 0.00130, P << 0.0001) and Hela (P = 0.00254, P = 0.0066) cells. According to the analysis using Starbase V2.0 online database, let-7a-5p could target TGFßR1 in cervical cancer cell lines, and the let-7a-5p mimic reduces the mRNA expression level of TGFßR1 in cervical cancer cell C33a (P = 0.0067). Western blot results showed that TGFBR1 expression significantly decreased in cervical cancer cells after let-7a-5p mimic treatment (P = 0.0048) and significantly increased after let-7a-5p mimic inhibitor treatment (P = 0.0003). CONCLUSIONS: let-7a-5p represents the independent novel anti-oncogenes in cervical cancer, which can regulate TGF-ß1/TGFBR1/pSmad3 cell pathway and interfere with the proliferation of cervical cancer cells. Therefore, let-7a-5p can serve as a novel potential therapeutic target for the treatment of cervical cancer.

Expression of LIN28A/B and Let-7 miRNAs in canine mammary carcinomas / Expressão de LIN28A/B e Let-7 miRNAs em carcinomas mamários caninos

LIN28 is a RNA-binding protein including two highly conserved homologous, LIN28A and LIN28B. Proto-oncogenes such as LIN28A and LIN28B are generally targeted by the let-7 miRNAs in different types of human cancers. Here, we determined the expression of LIN28A in canine mammary tumor samples and the LIN28/let-7 pathway in canine mammary cell lines. In those cell lines, we identified a functional LIN28/let-7 pathway which exhibited high expression of let-7 members and low expression of its targets, including LIN28A and LIN28B. However, the mammary carcinoma tissue samples showed a frequent expression of LIN28A being expressed mainly in the epithelial cells. No association was observed between LIN28A expression and histopathological classification and grade, TNM and survival time. Our results suggested a possible role of the LIN28A protein in the development of canine mammary carcinomas due to the high frequency observed in the tumor samples (28 of 32). The in vitro experiments suggested that the LIN28/let-7 pathway is active in the tumor cells evaluated. However, more studies are necessary to elucidate the exact role of LIN28/let-7 pathway in canine mammary carcinomas.

LIN28 é uma proteína de ligação ao RNA, com duas formas homólogas altamente conservadas, LIN28A e LIN28B. Os proto-oncogenes LIN28A e LIN28B são regulados pela família de miRNAs let-7 em diferentes tipos de cânceres em humanos. No presente trabalho, o objetivo foi determinar a expressão de LIN28A em amostras de tumor mamário de cadelas e a via LIN28/let-7 em linhagens celulares mamárias caninas. Nestas linhagens, através das técnicas de qPCR e RNAseq, foi identificado que a via LIN28/let-7 apresenta-se funcional, com alta expressão dos membros da família let-7 e baixa expressão de seus alvos, entre eles LIN28A e LIN28B. No entanto, as amostras de tecidos de carcinomas mamários caninos demonstraram expressão frequente de LIN28A, sendo observada principalmente em células epiteliais. Não foram observadas associações entre expressão de LIN28A com classificação e gradação histopatológicas, TNM e tempo de sobrevida. Nossos resultados sugerem uma possível relação da proteína LIN28A no desenvolvimento de carcinomas mamários caninos devido à alta frequência observada nas amostras tumorais (28 de 32). Os experimentos in vitro sugerem que a via LIN28/let-7 é ativa nas linhagens celulares caninas avaliadas. Entretanto, estudos funcionais ainda são necessários para elucidar a função exata da via LIN28/let-7 nos carcinomas mamários caninos.

let-7b-5p suppresses the proliferation and migration of pulmonary artery smooth muscle cells via down-regulating IGF1

Abstract Objectives Some previous studies indicated that the excessive proliferation and migration of Pulmonary Artery Smooth Muscle Cells (PASMCs) could be observed in pulmonary artery intima after Pulmonary Embolism (PE) occurred. In addition, recent studies identified some miRNAs that are differentially expressed in the blood of PE patients, which might be used as a diagnostic biomarker for PE, including let-7a-5p, let-7b-5p, and miR-150-5p. Hence, the authors sought to explore the effects of let-7b-5p in PASMC proliferation and migration and the corresponding regulatory mechanism. Methods Platelet-Derived Growth Factor (PDGF) was utilized to induce the hyper-proliferation model in PASMCs. The mRNA and protein expression levels were detected by RT-qPCR and western blot, respectively. The proliferation of PASMCs was evaluated by the detection of PCNA expression, as well as CCK-8 and Edu assays. Wound healing and Transwell assays were exploited to assess the migration ability of PASMCs. The targets of let-7b-5p were predicted based on two bioinformatics online tools. Dual-luciferase and Ago2 pull-down assays were applied to confirm the interaction between let-7b-5p and IGF1. Results 40 ng/mL PDGF was selected as the optimal concentration to induce PASMCs. let-7b-5p mimics suppressed the proliferation and migration of PDGF-induced PASMCs, while let-7b-5p inhibitor led to the opposite result. In further mechanism exploration, IGF1 was predicted and confirmed as the direct target gene of let-7b-5p. The promotion role of IGF1 overexpression on the proliferation and migration of PDGF-induced PASMCs was dramatically countered by let-7b-5p mimics. Conclusion let-7b-5p prohibits the proliferation and migration of PDGF-induced PASMCs by modulating IGF1.

Can increased expression of miR-Let-7c reduce the transition potential of high-grade urothelial carcinoma?

BACKGROUND: Bladder cancer is the leading transitional cell carcinoma affecting men and women with high morbidity and mortality rates, justifying the need to develop new molecular target therapies using microRNAs. This study aimed to evaluate the behavior of the T24 cell line after transfection with miR-Let-7c precursor mimic through invasion, migration, apoptosis, and cell cycle assays. METHODS AND RESULTS: T24 cell was transfected with the Let-7c mimic and its respective control and evaluated after 24 h. The expression levels of miR-Let-7c were analyzed by qPCR. We performed wound healing, Matrigel and flow cytometry, apoptosis, and cell cycle assays to determine its effect on cellular processes. Cells transfected with miR-Let-7c showed increased apoptosis rates (p = 0.019), decreased migration 24 h (p = 0.031) and 48 h (p = 0.0006), invasion potential (p = 0.0007), and cell proliferation (p = 0.002). CONCLUSIONS: Our results demonstrate that miR-Let-7c can act in different pathways of the carcinogenic cellular processes of muscle-invasive urothelial carcinoma cells, inhibiting cell proliferation and increasing apoptosis levels, consequently limiting their invasion potential. However, further studies should be carried out better to elucidate this microRNA's role in high-grade urothelial carcinomas and unveil which targets this microRNA may present, which are intrinsically related to the cancer survival pathways.

The Role of microRNAs in Pulp Inflammation.

The dental pulp can be affected by thermal, physical, chemical, and bacterial phenomena that stimulate the inflammatory response. The pulp tissue produces an immunological, cellular, and vascular reaction in an attempt to defend itself and resolve the affected tissue. The expression of different microRNAs during pulp inflammation has been previously documented. MicroRNAs (miRNAs) are endogenous small molecules involved in the transcription of genes that regulate the immune system and the inflammatory response. They are present in cellular and physiological functions, as well as in the pathogenesis of human diseases, becoming potential biomarkers for diagnosis, prognosis, monitoring, and safety. Previous studies have evidenced the different roles played by miRNAs in proinflammatory, anti-inflammatory, and immunological phenomena in the dental pulp, highlighting specific key functions of pulp pathology. This systematized review aims to provide an understanding of the role of the different microRNAs detected in the pulp and their effects on the expression of the different target genes that are involved during pulp inflammation.

MicroRNA Levels in Cervical Cancer Samples and Relationship with Lesion Grade and HPV Infection.

BACKGROUND: miR-21, miR-214 and miR-let-7a are three validated and well-known miRNAs. miR-21 is described as an "oncomir" while miR-214 and miR-let-7a are described mainly as tumor suppressors. The role of these miRNAs remains unclear in cervical cancer, an important malignancy among women worldwide and responsible for many deaths every year. OBJECTIVE: The objective of this study is to describe the expression profile of miR-21, miR-214 and miR-let-7a in plasma and in cervical scraping from a control group and patients with different grades of cervical lesions and invasive cervical cancer and correlate with HPV infection groups. METHODS: Plasma and cervical scraping were submitted to DNA and RNA extraction. HPV detection and typing were performed by conventional PCR followed by PAGE to amplicons interpretation. The miRNA relative expression in plasma and cervical scraping samples was performed by real time PCR using specific TaqMan probes. RESULTS: miR-21 (p=0.0277) and miR-214 (p=0.0151) were up-regulated in cervical scraping samples of invasive cervical cancer (ICC) group. However, miR-214 was also up-regulated in the LSIL group (p=0.0062). Both miRNAs were not related to HPV infection. However, miR-let-7a was higher in HPV positive plasma samples (p=0.0433) than in HPV negative plasma samples and the correlation analysis confirmed the association between the levels of this miRNA with the presence of HPV (p=0.0407; r=0.3029), but not with lesion grade (p>0.05). CONCLUSION: Our results suggest that miR-21 is related to cervical cancer progression and miR-214 appears to have an ambiguous role in cervical lesions. miR-let-7a may be upregulated at a systemic level in patients with HPV infection.

Age-related increase of let-7 family microRNA in rat retina and vitreous.

Vitreous alterations occur from early stages and continue through the normal aging, with gradual lamellae formation and the appearance of liquefied spaces, which eventually leads to complications, such as retinal tear, retinal detachment, and intravitreal hemorrhage. The aim of the present study was to investigate the expression of let-7 miRNA family in the vitreous and retina in newborn (1-3- day-old), young adult (2-month-old), and aging (12-month-old) rats, as well as their role as regulators of vitreous components. MicroRNAs are small, non-coding RNAs that post-transcriptionally regulate gene expression. Our results showed detection of all investigated let-7 isoforms (let-7a, let-7b, let-7c, let-7d, let-7e, let-7f and let-7i) in the retina and vitreous. Although most let-7 members were significantly upregulated in the vitreous during development, only let-7b, let-7c, and let-7e followed this same expression pattern in the retina. Let-7b and -7c increased in aging vitreous as well, and were expressed in vitro by Müller glial cells and their extracellular vesicles. Moreover, let-7 targeted hyaluronan synthase 2 (Has2) mRNA, a synthesizing enzyme of hyaluronan. These observations indicate that let-7 function is important during retina and vitreous development, and that isoforms of let-7 increased with aging, potentially modulating hyaluronan content.

Dysregulated Expression of Apoptosis-Associated Genes and MicroRNAs and Their Involvement in Gastric Carcinogenesis.

PURPOSE: Analyze the expression of caspase-9, Smac/DIABLO, XIAP, let-7a, and let-7b in patients with normal gastric tissue, chronic gastritis, and gastric adenocarcinoma. METHODS: The expression of caspase-9, Smac/DIABLO, XIAP, let-7a, and let-7b by qRT-PCR was analyzed in 158 samples from 53 patients with normal gastric mucosa, 86 with chronic gastritis, and 19 with gastric cancer. RESULTS: The comparison between the gastric cancer and the control group revealed a decreased expression of caspase-9 in gastric cancer tissues; considering the Helicobacter pylor presence, comparable results were revealed. Smac/DIABLO was increased in gastric cancer cells, while XIAP demonstrated no significant difference in the gene expression. The microRNA analysis revealed a decreased expression of let-7a and let-7b in samples positive to H. pylori infection and in gastric cancer group, regardless of the presence of the bacterium. CONCLUSION: Our study provided some evidence of low activity of the intrinsic apoptosis pathway, as well as the influence of H. pylori on let-7a and let-7b expression.

Role and Regulation of Lin28 in Progenitor Cells During Central Nervous System Development.

Lin28 is a highly conserved RNA binding protein that regulates stemness whose molecular role has been widely studied in vitro. However, the regulation and the molecular role of Lin28 during the development of the vertebrate central nervous system (CNS) in vivo are not completely understood. Here, the expression and the putative role of Lin28 in the development of the mammalian CNS are reviewed in the context of recent results showing the progressive cellular and molecular changes in neural progenitor cells. Downstream genes that may play a role during CNS development and the effect of misregulated expression of Lin28 are discussed. Evidence suggests that Lin28 promotes symmetric divisions over asymmetric divisions, increasing the number of progenitors during early neurogenesis. Future quantitative analysis of Lin28 isoforms levels and stabilities together with single cell transcriptomics data, cell cycle dynamics and cell fate analysis in Lin28 gain- and loss-of-function experiments will provide a better understanding of the molecular role of Lin28 during development.

Structural insights of the pre-let-7 interaction with LIN28B.

The Let-7:LIN28 regulatory loop is a paradigm in miRNA regulation. LIN28 harbors two RNA binding domains, which interact with well-conserved sequences in pre-let-7 RNAs, the GNGAY and the GGAG motifs. Here, the differential binding between LIN28B and pre-let-7 members was associated with the structural characteristics of the pre-let-7 family mapped by SHAPE, uncovering diverse structural patterns within pre-let-7 members. Pre-let-7 mutants supported a relevant role of the GGAG motif location and the preE-stem stability for the interaction with LIN28B. Based on these results, we propose a core RNA structure for LIN28B interaction.

Functional Characterization of the Lin28/let-7 Circuit During Forelimb Regeneration in Ambystoma mexicanum and Its Influence on Metabolic Reprogramming.

The axolotl (Ambystoma mexicanum) is a caudate amphibian, which has an extraordinary ability to restore a wide variety of damaged structures by a process denominated epimorphosis. While the origin and potentiality of progenitor cells that take part during epimorphic regeneration are known to some extent, the metabolic changes experienced and their associated implications, remain unexplored. However, a circuit with a potential role as a modulator of cellular metabolism along regeneration is that formed by Lin28/let-7. In this study, we report two Lin28 paralogs and eight mature let-7 microRNAs encoded in the axolotl genome. Particularly, in the proliferative blastema stage amxLin28B is more abundant in the nuclei of blastemal cells, while the microRNAs amx-let-7c and amx-let-7a are most downregulated. Functional inhibition of Lin28 factors increase the levels of most mature let-7 microRNAs, consistent with an increment of intermediary metabolites of the Krebs cycle, and phenotypic alterations in the outgrowth of the blastema. In summary, we describe the primary components of the Lin28/let-7 circuit and their function during axolotl regeneration, acting upstream of metabolic reprogramming events.

Downregulation of the Polycomb-Associated Methyltransferase Ezh2 during Maturation of Hippocampal Neurons Is Mediated by MicroRNAs Let-7 and miR-124.

Ezh2 is a catalytic subunit of the polycomb repressive complex 2 (PRC2) which mediates epigenetic gene silencing through depositing the mark histone H3 lysine 27 trimethylation (H3K27me3) at target genomic sequences. Previous studies have demonstrated that Enhancer of Zeste Homolog 2 (Ezh2) was differentially expressed during maturation of hippocampal neurons; in immature neurons, Ezh2 was abundantly expressed, whereas in mature neurons the expression Ezh2 was significantly reduced. Here, we report that Ezh2 is downregulated by microRNAs (miRs) that are expressed during the hippocampal maturation process. We show that, in mature hippocampal neurons, lethal-7 (let-7) and microRNA-124 (miR-124) are robustly expressed and can target cognate motifs at the 3'-UTR of the Ezh2 gene sequence to downregulate Ezh2 expression. Together, these data demonstrate that the PRC2 repressive activity during hippocampal maturation is controlled through a post-transcriptional mechanism that mediates Ezh2 downregulation in mature neurons.

Regulation of Lin28a-miRNA let-7b-5p pathway in skeletal muscle cells by peroxisome proliferator-activated receptor delta.

Lin28a/miRNA let-7b-5p pathway has emerged as a key regulators of energy homeostasis in the skeletal muscle. However, the mechanism through which this pathway is regulated in the skeletal muscle has remained unclear. We have found that 8 wk of aerobic training (Tr) markedly decreased let-7b-5p expression in murine skeletal muscle, whereas high-fat diet (Hfd) increased its expression. Conversely, Lin28a expression, a well-known inhibitor of let-7b-5p, was induced by Tr and decreased by Hfd. Similarly, in human muscle biopsies, Tr increased LIN28 expression and decreased let-7b-5p expression. Bioinformatics analysis of LIN28a DNA sequence revealed that its enrichment in peroxisome proliferator-activated receptor delta (PPARδ) binding sites, which is a well-known metabolic regulator of exercise. Treatment of primary mouse skeletal muscle cells or C2C12 cells with PPARδ activators GW501516 and AICAR increased Lin28a expression. Lin28a and let-7b-5p expression was also regulated by PPARδ coregulators. While PPARγ coactivator-1α (PGC1α) increased Lin28a expression, corepressor NCoR1 decreased its expression. Furthermore, PGC1α markedly reduced the let-7b-5p expression. PGC1α-mediated induction of Lin28a expression was blocked by the PPARδ inhibitor GSK0660. In agreement, Lin28a expression was downregulated in PPARδ knocked-down cells leading to increased let-7b-5p expression. Finally, we show that modulation of the Lin28a-let-7b-5p pathway in muscle cells leads to changes in mitochondrial metabolism in PGC1α dependent fashion. In summary, we demonstrate that Lin28a-let-7b-5p is a direct target of PPARδ in the skeletal muscle, where it impacts mitochondrial respiration.

Let-7 miRNA's Expression Profile and Its Potential Prognostic Role in Uterine Leiomyosarcoma.

The lethal-7 (let-7) family is an important microRNA (miRNA) group that usually exerts functions as a tumor suppressor. We aimed to evaluate the expression profile of let-7a, let-7b, let-7c, let-7d, let-7e, let-7f, let-7g, and let-7i and to assess their value as prognostic markers in uterine leiomyosarcoma (LMS) patients. The miRNAs expression profile was assessed in 34 LMS and 13 normal myometrium (MM) paraffin-embedded samples. All let-7 family members showed downregulation in LMS. Our findings showed that patients with let-7e downregulation had worse overall survival (OS) and is an independent prognostic factor (hazard ratio [HR] = 2.24). In addition, almost half the patients had distant metastasis. LMS patients with downregulated let-7b and let-7d had worse disease-free survival (DFS); they are not independent prognostic factors (HR = 2.65). Patients' ages were associated with let-7d, let-7e and let-7f (p = 0.0160) downregulation. In conclusion, all the let-7 family members were downregulated in LMS patients, and the greater the loss of expression of these molecules, the greater their relationship with worse prognosis of patients. Let-7e expression might influence the OS, while let-7b and le-7d might influence the DFS. The lowest expression levels of let-7d, let-7e, and let-7f were associated with the oldest patients. Our findings indicate strong evidence of let-7's role as a potential prognostic biomarker in LMS.

IcarisideII facilitates the differentiation of ADSCs to SCs via let-7i/STAT3 axis to preserve erectile function.

BACKGROUND: IcarisideII (ICAII) could promote the differentiation of adipose tissue-derived stem cells (ADSCs) to Schwann cells (SCs), leading to improvement of erectile function (EF) and providing a realistic therapeutic option for the treatment of erectile dysfunction (ED). However, the underlying molecular mechanisms of ADSCs and ICAII in this process remain largely unclear. METHODS: ADSCs were treated with different concentrations of ICAII. Cell proliferation was determined by MTT assay. qRT-PCR and western blot were performed to detect expressions of SCs markers, signal transducer and activator of transcription-3 (STAT3), and microRNA-let-7i (let-7i). Luciferase reporter assay was conducted to verify the regulatory relationship between let-7i and STAT3. The detection of intracavernosal pressure (ICP) and the ratio of ICP/mean arterial pressure (MAP) were used to evaluate the EF in bilateral cavernous nerve injury (BCNI) rat models. RESULTS: ICAII promoted cell proliferation of ADSCs in a dose-dependent manner. The mRNA and protein levels of SCs markers were increased by ICAII treatment in a dose-dependent manner in ADSCs. Moreover, let-7i was significantly decreased in ICAII-treated ADSCs and upregulation of let-7i attenuated ICAII-induced promotion of SCs markers. In addition, STAT3 was a direct target of let-7i and upregulated in ICAII-treated ADSCs. Interestingly, overexpression of STAT3 abated the let-7i-mediated inhibition effect on differentiation of ADSCs to SCs and rescued the ICAII-mediated promotion effect on it. Besides, combination treatment of ADSCs and ICAII preserved the EF of BCNI rat models, which was undermined by let-7i overexpression. CONCLUSION: ICAII was effective for preserving EF by promoting the differentiation of ADSCs to SCs via modulating let-7i/STAT3 pathway.

Overexpression of Lin28a delays Xenopus metamorphosis and down-regulates albumin independently of its translational regulation domain.

BACKGROUND: Lin28 regulates stem cell biology and developmental timing. At the molecular level Lin28 inhibits the biogenesis of the micro RNA let-7 and directly controls the transcription and translation of several genes. In Xenopus, Lin28 overexpression delays metamorphosis and affects the expression of genes of the thyroid hormone (TH) axis. The TH carrier albumin, synthesized by the liver, is down-regulated in limbs and tail after Lin28 overexpression. The molecular mechanisms underlying the interaction between Lin28, let-7, and the hypothalamus-pituitary-thyroid gland (HPT) axis are unknown. RESULTS: We found that precursor and mature forms of let-7 increase during Xenopus metamorphosis. In the liver, lin28b is down-regulated and albumin is up-regulated during metamorphosis. Overexpression of a truncated form of Lin28a (Lin28aΔC), which has been shown not to interact with RNA helicase A to regulate translation, delays metamorphosis, indicating that the translational regulation domain is not required to inhibit the HPT axis. Importantly, both full length Lin28a and Lin28aΔC block the increase of albumin mRNA in the liver independently of changes in TH signaling. CONCLUSIONS: These results suggest that Lin28 delays metamorphosis through regulation of let-7 and that the decrease of the TH carrier albumin is one of the early changes after Lin28 overexpression.

Association of rs712 polymorphism in a let-7 microRNA-binding site of KRAS gene with colorectal cancer in a Mexican population.

OBJECTIVES: The rs712 polymorphism in a let-7 microRNA-binding site at KRAS gene has been associated with cancer. To examine its association with rs712 polymorphism, we analyzed Mexican individuals with colorectal cancer (CRC) and healthy subjects. MATERIALS AND METHODS: Genotyping of the rs712 polymorphism was performed by polymerase chain reaction in 281 controls and 336 CRC patients. RESULTS: The observed frequencies of rs712 polymorphism indicated an associated protective factor for CRC (P=0.032). An association between genotype and the disease was evident in: colon localization (allele T, odds ratio (OR) 3.82, 95% confidence Intervals (CI) 2.77-5.28, P=0.0001), node metastasis (genotype TT, OR 2.49, 95% CI 1.45-4.28, P=0.0009), poor differentiation (genotype GT, OR 2.35, 95% CI 1.35-4.1, P=0.0033), and poor chemotherapy response (genotype GT, OR 2.6, 95% CI 1.7-4.24, P=0.0001). CONCLUSION: Comparison of the data from patients with control group showed that polymorphism of rs712 in KRAS gene was protective factor, which was associated with susceptibility for CRC. However, the genotypes TT and GT of rs712 polymorphism in KRAS could contribute significantly to colon localization, node metastasis, poor differentiation and poor chemotherapy response in CRC patients in this sample population.