还原、温度和pH三重响应性交联聚合物载药胶束的制备及其释药性能研究

本文利用自由基共聚法合成了一种多重响应性交联聚合物载药胶束,对其化学结构、纳米级形貌进行了表征,并测定其载药率。实验结果表明,交联聚合物载药胶束为尺寸约100 nm的球形颗粒;其在还原剂谷胱甘肽(GSH)作用下可发生降解并溶胀;交联聚合物载药胶束的低临界溶液温度(LCST)为39.4℃,当环境温度高于LCST时,该胶束结构发生明显收缩。本研究分析了该交联聚合物载药胶束在模拟肿瘤微环境下的载药释放情况,即当该交联聚合物载药胶束处于酸性(p H 5.0)、还原性(GSH 10 mmol/L)和高温(42.0℃)条件下时,受条件刺激可促进其中药物释放,其累积释放率可达91.78%,而该交联聚合物载药胶束在无刺激条件下累积释放率仅为1.12%。细胞毒性实验进一步表明,本文合成的交联聚合物载药胶束表现出了较强的细胞摄取能力,具有良好的生物相容性和较好的体外抗肿瘤活性。基于以上研究结果,本实验中制备的交联聚合物载药胶束具有多重响应性释药功能,有望成为一种具备高效可控释药功能的理想载体材料。     

Cytoplasmic localization of p27 (cyclin-dependent kinase inhibitor 1B/KIP1) in colorectal cancer: inverse correlations with nuclear p27 loss, microsatellite instability, and CpG island methylator phenotype

Cytoplasmic mislocalization of p27 (CDKN1B/KIP1) is caused by activated AKT1 and has been associated with poor prognosis in various cancers. CIMP in colorectal cancer is characterized by extensive promoter methylation and is associated with MSI-MSI-H and BRAF mutations. We have recently shown a positive correlation between MSI/CIMP and loss of nuclear p27. However, no study has examined cytoplasmic p27 mislocalization in relation to CIMP and MSI in colorectal cancer. Using MethyLight assays, we quantified DNA methylation in 8 CIMP-specific gene promoters (CACNA1G, CDKN2A (p16), CRABP1, IGF2, MLH1, NEUROG1, RUNX3, and SOCS1) in 853 colorectal cancer samples obtained from 2 large prospective cohorts. We assessed expressions of nuclear and cytoplasmic p27 and nuclear p53 by immunohistochemistry. Cytoplasmic p27 expression was inversely associated with loss of nuclear p27 (P < .0001), CIMP-high (P < .0001), MSI-H (P < .0001), and BRAF mutations (P < .0001). The inverse association of cytoplasmic p27 with CIMP-high (or MSI-H) was independent of MSI (or CIMP) status. In addition, the inverse association of cytoplasmic p27 with CIMP-high was independent of KRAS/BRAF status. BRAF and CDKN2A (p16) methylation were not correlated with cytoplasmic p27 after stratification by CIMP status. The inverse associations of cytoplasmic p27 with MSI-H and CIMP-high were much more pronounced in p53-negative than p53-positive tumors. In conclusion, cytoplasmic p27 expression is inversely associated with MSI-H and CIMP-high, particularly in p53-negative tumors, suggesting interplay of functional losses of p27 and p53 in the development of various molecular subtypes of colorectal cancer.