Substantial evidence indicates that cancer-associated fibroblasts (CAFs) are critical components in the process of cancer progression. However, the role of CAFs in the immunopathogenesis of human cancer remains elusive. In this study, we demonstrate that purified colorectal carcinoma-derived fibroblasts exhibit activated phenotypes characterized by substantial α-smooth muscle actin expression. These CAFs sharply suppress natural killer (NK) cell functions in co-culture experiments. In contrast, normal skin fibroblasts had only a minimal effect on NK cell phenotype and function. Moreover, we demonstrated that prostaglandin E2 (PGE2) was released by fibroblasts in co-culture experiments. Thus, the functional modulation of NK cells by CAFs may represent a novel mechanism linking the pro-inflammatory response to immune tolerance within the tumor milieu.
We reported two Au clusters with precisely controlled molecular size (AuPeptide and AuPeptide) showing different antitumor effects. In vitro, both AuPeptide and AuPeptide were well taken up by human nasopharyngeal cancer cells (CNE1 cells). However, only AuPeptide significantly induced CNE1 cell apoptosis. Further studies showed that CNE1 cells took up AuPeptide (1.98 × 10 mol/cell), and 9% of them entered mitochondria (0.186 × 10 mol/cell). As a comparison, the uptake of AuPeptide was only half the amount of AuPeptide (1.11 × 10 mol/cell), and only 1% of them entered mitochondria (0.016 × 10 mol/cell). That gave 11.6-fold more AuPeptide in mitochondria of CNE1 cells than AuPeptide. Further cell studies revealed that the antitumor effect may be due to the enrichment of AuPeptide in mitochondria. AuPeptide slightly decreased the Mcl-1 (antiapoptotic protein of mitochondria) and significantly increased the Puma (pro-apoptotic protein of mitochondria) expression level in CNE1 cells, which resulted in mitochondrial transmembrane potential change and triggered the caspase 9-caspase 3-PARP pathway to induce CNE1 cell apoptosis. In vivo, CNE1 tumor growth was significantly suppressed by AuPeptide in the xenograft model after 3 weeks of intraperitoneal injection. The TUNEL and immuno-histochemical studies of tumor tissue verified that CNE1 cell apoptosis was mainly via the Puma and Mcl-1 apoptosis pathway in the xenograft model, which matched the aforementioned CNE1 cell studies in vitro. The discovery of Au but not Au suppressing tumor growth via the mitochondria target was a breakthrough in the nanomedical field, as this provided a robust approach to turn on/off the nanoparticles' medical properties via atomically controlling their sizes.
Despite the precise controllability of droplet samples in digital microfluidic (DMF) systems, their capability in isolating single cells for long-time culture is still limited: typically, only a few cells can be captured on an electrode. Although fabricating small-sized hydrophilic micropatches on an electrode aids single-cell capture, the actuation voltage for droplet transportation has to be significantly raised, resulting in a shorter lifetime for the DMF chip and a larger risk of damaging the cells. In this work, a DMF system with 3D microstructures engineered on-chip is proposed to form semiclosed micro-wells for efficient single-cell isolation and long-time culture. Our optimum results showed that approximately 20% of the micro-wells over a 30 × 30 array were occupied by isolated single cells. In addition, lowevaporation-temperature oil and surfactant aided the system in achieving a low droplet actuation voltage of 36V, which was 4 times lower than the typical 150 V, minimizing the potential damage to the cells in the droplets and to the DMF chip. To exemplify the technological advances, drug sensitivity tests were run in our DMF system to investigate the cell response of breast cancer cells (MDA-MB-231) and breast normal cells (MCF-10A) to a widely used chemotherapeutic drug, Cisplatin (Cis). The results on-chip were consistent with those screened in conventional 96well plates. This novel, simple and robust single-cell trapping method has great potential in biological research at the single cell level.
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