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Gemcitabine has been considered a first-line chemotherapy agent for the treatment of pancreatic cancer. However, the initial response rate of gemcitabine is low and chemoresistance occurs frequently. Aptamers can be effectively internalized into cancer cells via binding to target molecules with high affinity and specificity. In the current study, we constructed an aptamer-based gemcitabine delivery system, APTA-12, and assessed its therapeutic effects on pancreatic cancer cells in vitro and in vivo. APTA-12 was effective in vitro and in vivo in pancreatic cancer cells with high expression of nucleolin. The results of in vitro cytotoxicity assays indicated that APTA-12 inhibited the growth of pancreatic cancer cell lines. In vivo evaluation showed that APTA-12 effectively inhibited the growth of pancreatic cancer in Capan-1 tumor-bearing mice compared to mice that received gemcitabine alone or vehicle. These results suggest that the gemcitabine-incorporated APTA-12 aptamer may be a promising targeted therapeutic strategy for pancreatic cancer.

Background/PurposeAptamers are oligonucleotide or peptide molecules that bind to a target molecule with high affinity and specificity. The present study aimed to evaluate the target specificity and applicability for in vivo molecular imaging of an aptamer labeled with a radioisotope.MethodsThe human epidermal growth factor receptor 2 (HER2/ErbB2) aptamer was radiolabeled with 18F-fluoride. HER2-positive tumor cell uptake of the aptamer was evaluated in comparison to negative controls by flow cytometry and confocal microscopy. Using 18F-labeled HER2-specific aptamer positron emission tomography (PET), in vivo molecular images of BT474 tumor-bearing mice were taken at 60, 90 and 120 minutes after injection.ResultsIn flow cytometric analysis, HER2 aptamer showed strong binding to HER2-positive BT474 cells, while binding to HER2-negative MDA-MB231 cells was quite low. Likewise, in confocal microscopic images, the aptamer was bound to HER2-positive breast cancer cells, with minimal binding to HER2-negative cells. In vivo PET molecular imaging of BT474 tumor-bearing mice revealed significant higher uptake of the 18F-labeled HER2 specific aptamer into the tumor compared to the that of HER2-negative cell tumor(p = 0.033). HER2 aptamer was able to preferentially bind to HER2-positive breast cancer cells both in vitro and in vivo, by recognizing HER2 structure on the surface of these cells.ConclusionThe 18F-labeled aptamer enabled appropriate visualization of HER2 expression by human breast cancer cells. The results suggest that a radiolabeled HER2 aptamer could potentially be applied in the development of treatment strategies or in targeted therapy against HER2-positive breast cancer cells.

CCR3, the receptor for CCL11, is expressed on the surface of immune cells and even on non-immune cells. CCL11-CCR3 interactions can promote cell migration and proliferation. In this study, we investigated the effect of CCL11 on angiogenesis in HUVECs and also examined the molecular mechanisms of this process. We found that CCL11 induced mRNA transcription and protein expression of CCR3 in HUVECs. Moreover, the scratch wound healing assay and MTS proliferation assay both demonstrated that CCL11 promotes endothelial cell migration and induces weak proliferation. CCL11 directly induced microvessel sprouting from the rat aortic ring; these effects occurred earlier and to a greater extent than with VEGF stimulation. Furthermore, CCL11-induced phosphorylation of Akt was abolished by PI3K inhibitors. siRNA-mediated knockdown of CCR3 led to a significant reduction of PI3K phosphorylation. However, the phosphorylation levels of ERK1/2 were not changed, even after CCL11 treatment. Cumulatively, our data suggest that the CCL11-CCR3 interaction mainly activates PI3K/Akt signal transduction pathway in HUVECs.

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Hypoxia is a condition in which the whole body or a region of the body is deprived of oxygen supply. The brain is very sensitive to the lack of oxygen and cerebral hypoxia can rapidly cause severe brain damage. Astrocytes are essential for the survival and function of neurons. Therefore, protecting astrocytes against cell death is one of the main therapeutic strategies for treating hypoxia. Hence, the mechanism of hypoxia-induced astrocytic cell death should be fully elucidated. In this study, astrocytes were exposed to hypoxic conditions using a hypoxia work station or the hypoxia mimetic agent cobalt chloride (CoCl 2 ). Both the hypoxic gas mixture (1% O 2 ) and chemical hypoxia-induced apoptotic cell death in T98G glioblastoma cells and mouse primary astrocytes. Reactive oxygen species were generated in response to the hypoxiamediated activation of caspase-1. Active caspase-1 induced the classical caspase-dependent apoptosis of astrocytes. In addition, the microRNA processing enzyme Dicer was cleaved by caspase-3 during hypoxia. Knockdown of Dicer using antisense oligonucleotides induced apoptosis of T98G cells. Taken together, these results suggest that astrocytic cell death during hypoxia is mediated by the reactive oxygen species/caspase-1/classical caspase-dependent apoptotic pathway. In addition, the decrease in Dicer levels by active caspase-3 amplifies this apoptotic pathway via a positive feedback loop. These findings may provide a new target for therapeutic interventions in cerebral hypoxia.

Hepatocellular carcinoma (HCC) is the most common malignancy of the liver, which can progress rapidly and has a poor prognosis. Glypican-3 (GPC3) has been proposed to be an important diagnostic biomarker and therapeutic target for HCC. Aptamers have emerged as promising drug delivery vehicles because of their high binding affinity for target molecules. Herein, we developed G12msi, a gemcitabine-incorporated DNA aptamer, targeting GPC3, and evaluated its binding specificity and anti-tumor efficacy in GPC3-overexpressing HCC cell lines and murine xenograft models. GPC3-targeted aptamers were selected by using the SELEX process and the chemotherapy drug gemcitabine was internally incorporated into the aptamer. To determine the binding affinity and internalization of the G12msi, flow cytometry and confocal microscopy were performed on GPC3-positive HepG2, Hep3B, and Huh7 cells, as well as a GPC3-negative A431 cell. The anti-tumor activities of G12msi were evaluated with in vitro and in vivo models. We found that G12msi binds to GPC3-overexpressing HCC tumor cells with high specificity and is effectively internalized. Moreover, G12msi treatment inhibited the cell proliferation of GPC3-positive HCC cell lines with minimal cytotoxicity in control A431 cells. In vivo systemic administration of G12msi significantly inhibited tumor growth of HCC HepG2 cells in xenograft models without causing toxicity. These results suggest that gemcitabine-incorporated GPC3 aptamer-based drug delivery may be a promising strategy for the treatment of HCC.