Lentivirus-delivered ZEB-1 small interfering RNA inhibits lung adenocarcinoma cell growth in vitro and in vivo

The effect of downregulation of Stathmin gene on biological behaviors of U373 and U87-MG glioblastoma cells

Background

Stathmin as a critical protein involved in microtubule polymerization, is necessary for survival of cancer cells. However, extremely little is known about Stathmin in glioblastoma. So, this study was designed to elucidate the function of Stathmin gene in the tumorigenesis and progression of glioblastoma cells.

Method

The lentiviral interference vector pLV3-si-Stathmin targeting Stathmin gene and the control vector pLV3-NC were established for the co-transfection of 293T cells together with the helper plasmids. Viral titer was determined via limiting dilution assay. Then pLV3-si-Stathmin and pLV3-NC were stably co-transfected into U373 and U87-MG glioblastoma cells. Expression levels of Stathmin protein in each group were determined by using Western Blot, and the proliferation and migration ability of the cells with downregulated Stathmin were evaluated through CCK8 assay and transwell invasion assay, respectively. Cell cycles and cell apoptosis were detected with flow cytometry. Finally, the effect of Stathmin in tumor formation was determined in nude mice.

Result

DNA sequencing and viral titer assay indicated that the lentiviral interference vector was successfully established with a viral titer of 4 × 10⁸ TU/ml. According to the results from Western Blotting, Stathmin protein expression level decreased significantly in the U373 and U87-MG cells after transfected with pLV3-si-Stathmin, respectively, compared with those transfected with pLV3-NC. In glioblastoma cells, the cell proliferation and migration were greatly inhibited after the downregulation of Stathmin protein. Flow cytometry showed that much more cells were arrested in G2/M phasein Stathmin downregulated group, compared with the non-transfection group and NC group. But Stathmin downregulation did not induce significant cell apoptosis. Tumor formation assay in nude mice showed that tumor formation was delayed after Stathmin downregulation, with a reduction in both tumor formation rate and tumor growth velocity.

Conclusion

Stathmin downregulation affected the biological behaviors of U373 and U87-MG glioblastoma cells, inhibiting the proliferation and migration of tumor cells. Stathmin gene may serve as a potential target in gene therapy for glioblastoma.

Zinc finger E-box-binding homeobox 1: its clinical significance and functional role in human thyroid cancer

Objective

Transcription factor zinc finger E-box-binding homeobox 1 (ZEB1), as one of the key inducers of epithelial-mesenchymal transition, has been reported to be regulated by microRNA-144 and Bcl-2-associated athanogene 3, which both promote thyroid cancer cell invasion. However, the involvement of ZEB1 in thyroid cancer has not been fully elucidated. In this study, we aimed to investigate the role and clinical implication of ZEB1 in this disease.

Methods

Immunohistochemistry was performed to examine the subcellular localization and the expression level of ZEB1 protein in 82 self-pairs of formalin-fixed and paraffin-embedded cancerous and adjacent noncancerous tissues obtained from patients with thyroid cancer. The roles of ZEB1 in thyroid cancer cell migration, invasion, and proliferation were also detected by transwell and MTT analyses, respectively.

Results

Immunohistochemistry showed that ZEB1 was predominantly localized in the nucleus of thyroid cancer cells. Its immunoreactive score in thyroid cancer tissues was significantly higher than that in adjacent noncancerous tissues (P=0.01). In addition, ZEB1 overexpression was significantly associated with the advanced tumor node metastasis staging (P=0.008), the positive lymph node metastasis (P=0.01) and distant metastasis (P=0.02). Furthermore, ZEB1 knockdown by siRNA could efficiently inhibit the migration, invasion, and proliferation abilities of thyroid cancer cells in vitro.

Conclusion

These findings indicated that ZEB1 might function as an oncogene, the overexpression of which was associated with the aggressive tumor progression of human thyroid cancer. Interestingly, ZEB1 also could promote thyroid cancer cell migration, invasion, and proliferation, suggesting that the inhibition of this protein might be a therapeutic strategy for the treatment of this malignancy.

microRNA-200b as a Switch for Inducible Adult Angiogenesis

SIGNIFICANCE

Angiogenesis is the process by which new blood vessels develop from a pre-existing vascular system. It is required for physiological processes such as developmental biology and wound healing. Angiogenesis also plays a crucial role in pathological conditions such as tumor progression. The underlying importance of angiogenesis necessitates a highly regulated process.

RECENT ADVANCES

Recent works have demonstrated that the process of angiogenesis is regulated by small noncoding RNA molecules called microRNAs (miRs). These miRs, collectively referred to as angiomiRs, have been reported to have a profound effect on the process of angiogenesis by acting as either pro-angiogenic or anti-angiogenic regulators.

CRITICAL ISSUES

In this review, we will discuss the role of miR-200b as a regulator of angiogenesis. Once the process of angiogenesis is complete, anti-angiogenic miR-200b has been reported to provide necessary braking. Downregulation of miR-200b has been reported across various tumor types, as deregulated angiogenesis is necessary for tumor development. Transient downregulation of miR-200b in wounds drives wound angiogenesis.

FUTURE DIRECTIONS

New insights and understanding of the molecular mechanism of regulation of angiogenesis by miR-200b has opened new avenues of possible therapeutic interventions to treat angiogenesis-related patho-physiological conditions. Antioxid. Redox Signal. 22, 1257-1272.

Development of small RNA delivery systems for lung cancer therapy

RNA interference (RNAi) has emerged as a powerful tool for studying target identification and holds promise for the development of therapeutic gene silencing. Recent advances in RNAi delivery and target selection provide remarkable opportunities for translational medical research. The induction of RNAi relies on small silencing RNAs, which affect specific messenger RNA (mRNA) degradation. Two types of small RNA molecules, small interfering RNAs (siRNAs) and microRNAs (miRNAs), have a central function in RNAi technology. The success of RNAi-based therapeutic delivery may be dependent upon uncovering a delivery route, sophisticated delivery carriers, and nucleic acid modifications. Lung cancer is still the leading cause of cancer death worldwide, for which novel therapeutic strategies are critically needed. Recently, we have reported a novel platform (PnkRNA™ and nkRNA^®) to promote naked RNAi approaches through inhalation without delivery vehicles in lung cancer xenograft models. We suggest that a new class of RNAi therapeutic agent and local drug delivery system could also offer a promising RNAi-based strategy for clinical applications in cancer therapy. In this article, we show recent strategies for an RNAi delivery system and suggest the possible clinical usefulness of RNAi-based therapeutics for lung cancer treatment.

Non-coding RNAs in lung cancer

The discovery that protein-coding genes represent less than 2% of all human genome, and the evidence that more than 90% of it is actively transcribed, changed the classical point of view of the central dogma of molecular biology, which was always based on the assumption that RNA functions mainly as an intermediate bridge between DNA sequences and protein synthesis machinery. Accumulating data indicates that non-coding RNAs are involved in different physiological processes, providing for the maintenance of cellular homeostasis. They are important regulators of gene expression, cellular differentiation, proliferation, migration, apoptosis, and stem cell maintenance. Alterations and disruptions of their expression or activity have increasingly been associated with pathological changes of cancer cells, this evidence and the prospect of using these molecules as diagnostic markers and therapeutic targets, make currently non-coding RNAs among the most relevant molecules in cancer research. In this paper we will provide an overview of non-coding RNA function and disruption in lung cancer biology, also focusing on their potential as diagnostic, prognostic and predictive biomarkers.

ZEB1 knockdown mediated using polypeptide cationic micelles inhibits metastasis and effects sensitization to a chemotherapeutic drug for cancer therapy

Metastasis and drug resistance are the main causes for the failure in clinical cancer therapy. Emerging evidence suggests an intricate role of epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs) in metastasis and drug resistance. The EMT-activator ZEB1 is crucial in malignant tumor progression by linking EMT-activation and stemness-maintenance. Here, we used multifunctional polypeptide micelle nanoparticles (NP) as nanocarriers for the delivery of ZEB1 siRNA and doxorubicin (DOX). The nanocarriers could effectively deliver siRNA to the cytoplasm and knockdown the target gene in H460 cells and H460 xenograft tumors, leading to reduced EMT and repressed CSC properties in vitro and in vivo. The complex micelle nanoparticles with ZEB1 siRNA (siRNA-NP) significantly reduced metastasis in the lung. When DOX and siRNA were co-delivered by the nanocarriers (siRNA-DOX-NP), a synergistic therapeutic effect was observed, resulting in dramatic inhibition of tumor growth in a H460 xenograft model. These results demonstrated that the siRNA-NP or siRNA-DOX-NP complex targeting ZEB1 could be developed into a new therapeutic approach for non-small cell lung cancer (NSCLC) treatment.

Integrated Analysis of Dysregulated miRNA-gene Expression in HMGA2-silenced Retinoblastoma Cells

Retinoblastoma (RB) is a primary childhood eye cancer. HMGA2 shows promise as a molecule for targeted therapy. The involvement of miRNAs in genome-level molecular dys-regulation in HMGA2-silenced RB cells is poorly understood. Through miRNA expression microarray profiling, and an integrated array analysis of the HMGA2-silenced RB cells, the dysregulated miRNAs and the miRNA-target relationships were modelled. Loop network analysis revealed a regulatory association between the transcription factor (SOX5) and the deregulated miRNAs (miR-29a, miR-9*, miR-9-3). Silencing of HMGA2 deregulated the vital oncomirs (miR-7, miR-331, miR-26a, miR-221, miR-17~92 and miR-106b∼25) in RB cells. From this list, the role of the miR-106b∼25 cluster was examined further for its expression in primary RB tumor tissues (n = 20). The regulatory targets of miR-106b∼25 cluster namely p21 (cyclin-dependent kinase inhibitor) and BIM (pro-apoptotic gene) were elevated, and apoptotic cell death was observed, in RB tumor cells treated with the specific antagomirs of the miR-106b∼25 cluster. Thus, suppression of miR-106b∼25 cluster controls RB tumor growth. Taken together, HMGA2 mediated anti-tumor effect present in RB is, in part, mediated through the miR-106b∼25 cluster.

siRNA delivery to the lung: what's new?

RNA interference (RNAi) has been thought of as the general answer to many unmet medical needs. After the first success stories, it soon became obvious that short interfering RNA (siRNA) is not suitable for systemic administration due to its poor pharmacokinetics. Therefore local administration routes have been adopted for more successful in vivo RNAi. This paper reviews nucleic acid modifications, nanocarrier chemistry, animal models used in successful pulmonary siRNA delivery, as well as clinical translation approaches. We summarize what has been published recently and conclude with the potential problems that may still hamper the efficient clinical application of RNAi in the lung.

Epithelial to mesenchymal transition inducing transcription factors and metastatic cancer

The epithelial to mesenchymal transition (EMT) is an important step for the developmental process. Recent evidences support that EMT allows the tumor cells to acquire invasive properties and to develop metastatic growth characteristics. Some of the transcription factors, which are actively involved in EMT process, have a significant role in the EMT-metastasis linkage. A number of studies have reported that EMT-inducing transcription factors (EMT-TFs), such as Twist, Snail, Slug, and Zeb, are directly or indirectly involved in cancer cell metastasis through a different signaling cascades, including the Akt, signal transducer and activator of transcription 3 (STAT3), mitogen-activated protein kinase (MAPK) and Wnt pathways, with the ultimate consequence of the downregulation of E-cadherin and upregulation of metastatic proteins, such as N-cadherin, vimentin, matrix metalloproteinase (MMP)-2, etc. This review summarizes the update information on the association of EMT-TFs with cancer metastasis and the possible cancer therapeutics via targeting the EMT-TFs.

miR-655 Is an EMT-suppressive microRNA targeting ZEB1 and TGFBR2

Recently, the epithelial-to-mesenchymal transition (EMT) has been demonstrated to contribute to normal and disease processes including cancer progression. To explore EMT-suppressive microRNAs (miRNAs), we established a cell-based reporter system using a stable clone derived from a pancreatic cancer cell line, Panc1, transfected with a reporter construct containing a promoter sequence of CDH1/E-cadherin in the 5′ upstream region of the ZsGreen1 reporter gene. Then, we performed function-based screening with 470 synthetic double-stranded RNAs (dsRNAs) mimicking human mature miRNAs using the system and identified miR-655 as a novel EMT-suppressive miRNA. Overexpression of miR-655 not only induced the upregulation of E-cadherin and downregulation of typical EMT-inducers but also suppressed migration and invasion of mesenchymal-like cancer cells accompanied by a morphological shift toward the epithelial phenotype. In addition, we found a significant correlation between miR-655 expression and a better prognosis in esophageal squamous cell carcinoma (ESCC). Moreover, ZEB1 and TGFBR2, which are essential components of the TGF-b signaling pathway, were identified as direct targets of miR-655, suggesting that the activation of the TGF-b-ZEB1-E-cadherin axis by aberrant downregulation of miR-655 may accelerate cancer progression.