Purpose: Prostate cancer is the second leading cause of cancer deaths among men in Western counties, which has also occurred in Chinese male with markedly increasing incidence in recent years. Although the mechanism underlying its progression still remains unclear, epigenetic modifications are important ethological parameters. The purpose of this study is to determine the methylation status and function of hypermethylatioted in cancer 1 (HIC1) in prostate cancer progression.Experimental Design: The methylation status of HIC1 promoter was assayed in cell lines, tissues, and plasma of patients with prostate cancer by using methylation-specific PCR and bisulfate sequencing PCR. The ability of HIC1 to regulate proliferation, migration, and invasion was assessed by MTT, scratch-healing assay, and reconstituted extracellular matrices in porous culture chambers. Tumorigenesis, metastases, and bone destruction were analyzed in mice bearing prostate cancer cells restoring HIC1 by using Xenogen IVIS with radiographic system and small-animal positron emission tomography computed tomographic images. Microarrays were searched for genes that had correlated expression with HIC1 mRNA. Reporter gene assays were used to determine whether HIC1 affected the expression of CXCR7, and chromatin immunoprecipitation was used to determine whether HIC1 bound to CXCR7 promoters. All P values were determined using 2-sided tests.Results: The methylation status of 11 CpG sites within HIC1 promoter was abundantly methylated in cell lines, tissues, and plasma of patients with prostate cancer compared with those of respective normal controls. Restoring HIC1 expression in prostate cancer cells markedly inhibited proliferation, migration, and invasion and induced the apoptosis in these cells. Moreover, mice bearing prostate cancer-restoring HIC1 cells had a marked effect on reducing tumor growth, multiple tissue metastases, and bone destruction. Notably, we also identified that the chemokine receptor CXCR7 is a direct downstream target gene of HIC1. Finally, we showed that CXCR7 promoter in prostate cancer cells is negatively regulated by HIC1, which may be responsible for prostate cancer progression.Conclusions: Our data show for the first time that hypermethylation of HIC1 promoter results in loss of its repressive function, responsible for prostate cancer progression and invasion. These findings suggest that therapies targeting epigenetic events regulating HIC1 expression may provide a more effective strategy for prostate cancer treatment.

Complex coacervation can be used as a route to compartmentalize a variety of solutes such as organic small molecules, inorganic nanoparticles, and proteins within microscale coacervate droplets. To obtain insight into the accumulation of proteins within complex coacervate phases, the encapsulation of Bovine Serum Albumin (BSA) within complex coacervates containing cationic polyelectrolyte poly(allylamine hydrochloride) (PAH) and anionic polyelectrolyte poly(acrylic aid) (PAA) was investigated as a function of mixing sequence, total polyelectrolyte concentration, BSA overall concentration, and the mixing molar ratio of PAA/PAH. Mixing BSA having a negative net charge with the polycation PAH before coacervation, increasing the total polyelectrolyte concentration and PAA/PAH molar ratio, or decreasing the BSA overall concentration led to more efficient protein encapsulation. Preservation of the secondary structure of BSA during the complex coacervation process was confirmed using circular dichroism spectroscopy. Our study shows that PAA-PAH coacervates can serve as a protective system against the denaturation of BSA when exposed to extremes of pH, high temperatures, as well as in solution of urea. Additionally, it was found that by encapsulation of proteins within coacervates via complex coacervation, the complexation between proteins and heavy metal can be efficiently inhibited. Protection of BSA against severe environmental conditions via encapsulation within polyelectrolyte coacervates provides new insights and methods to issues of maintaining stability and function of proteins.

Polyelectrolyte complex coacervation is a process that has been proposed as a model for protocell formation due to its ability to compartmentalize chemicals in solution without a membrane. During the liquid-liquid phase separation that results in water rich and polyelectrolyte rich phases, small molecules present in solution selectively partition to one phase over the other. This sequestration is based on relative affinities. Here, a study of the sequestration of methylene blue (MB) into the complex coacervate phase of three pairs of synthetic polyelectrolytes is presented; branched polyethylene imine with polyacrylic acid, polyvinyl sulfonate, or poly(4-styrenesulfonic acid). These materials are characterized with UV-vis, zeta potential measurements, and dynamic light scattering. The branched polyethylene imine/poly(4-styrenesulfonic acid) system is shown to have a significantly higher sequestration capacity for the MB as compared to either of the other two systems, based on π-π interactions which are not possible in the other systems.

Complex coacervation of polymers can be a route to the compartmentalization of aqueous solutions. Presented here is a study of the hydrogen-bonded complex coacervation of poly­(acrylic acid) and poly­(ethylene glycol) or Pluronic block copolymers and the ability of these coacervates to encapsulate various ionic and nonionic dyes as well as a pharmaceutical compound within them. The formation of complex coacervate driven by hydrogen bonding is studied as a function of both pH and salt content with turbidimetry and isothermal calorimetry. Small-angle X-ray scattering shows the presence of micelles within Pluronic containing coacervate materials formed with a Pluronic block copolymer concentration higher than its critical micelle concentration. Although dyes generally partition to the coacervate phase, in the absence of salt, dyes that are able to hydrogen bond with the coacervate components are better incorporated into the coacervate. It is observed that the addition of salt to the polymer solutions increases the hydrophobicity of the environment within the coacervate, increasing the ability to sequester dye molecules for which there is no hydrogen bonding with the coacervate components. These materials are characterized with UV–vis spectroscopy, dynamic light scattering, zeta potential measurements, isothermal calorimetry, small-angle X-ray scattering, and fluorescence spectroscopy.

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