Rubenstein Marvin, Anderson Kenning M, Tsui Paulus, Guinan Patrick
Division of Cellular Biology, Hektoen Institute for Medical Research, 2100 W. Harrision Street, Chicago, IL 60612, United States.
Med Hypotheses. 2006;67(6):1375-80. doi: 10.1016/j.mehy.2006.05.055. Epub 2006 Jul 25.
Antisense oligonucleotides (oligos) directed against transforming growth factor-alpha (TGF-alpha) and its binding site, the epidermal growth factor receptor (EGFR), have demonstrated in vitro and in vivo efficacy against both the PC-3 and LNCaP prostate tumor models. In an attempt to increase the efficiency of these oligos a new type of antisense compound called a bispecific oligo has been evaluated in vitro both alone and in combination with traditional chemotherapeutic agents. These bispecifics, which were first proposed in this journal in 2004, include binding sites for both TGF-alpha and EGFR along the same stretch of complementary DNA. Such bispecifics are able to deliver essentially two antisense activities in an equal molar ratio and can be directed against mRNA encoding proteins of different biochemical pathways. The first bispecifics were developed against two proteins regulating a single autocrine loop. Subsequent bispecifics have been developed which target both EGFR and the apoptosis regulating protein bcl-2. Bispecific activity of a single linear sequence oligo has already been shown to have efficacy. To further develop this multispecific approach, we now propose a branched antisense compound, again, having multiple binding site activities (to complementary sequenced mRNA). Active oligos would be attached to a fat soluble backbone which might enhance targeting and also intracellular entry, release and activity. Such a structure would also permit the customization of these branched forms to include oligos targeting specific proteins related to the growth of various tumor types. Problems associated with the development of antisense oligos have included both membrane solubility and specific targeting. By designing this branched form of antisense structure, multiple activities can be retained (added), solubility improved and delivery enhanced. Such a new formulation would include several antisense oligos covalently bound to and branching off from a lipid-like backbone. An elongated hydrocarbon chain would increase fat solubility and would permit oligo incorporation into nanoparticles or liposome derived delivery vehicles. Specific delivery of oligos could also be enhanced by the tendency of these nanoparticle or liposomal microbubbles to be disrupted under the influence of ultrasonic waves beamed at the targeted tissue.
针对转化生长因子α（TGF-α）及其结合位点表皮生长因子受体（EGFR）的反义寡核苷酸（oligos）已在体外和体内对PC-3和LNCaP前列腺肿瘤模型显示出疗效。为了提高这些寡核苷酸的效率，一种新型的反义化合物——双特异性寡核苷酸已在体外单独以及与传统化疗药物联合进行了评估。这些双特异性寡核苷酸于2004年首次在本期刊中提出，在同一段互补DNA上包含TGF-α和EGFR的结合位点。这种双特异性寡核苷酸能够以等摩尔比传递两种基本的反义活性，并且可以针对编码不同生化途径蛋白质的mRNA。最初的双特异性寡核苷酸是针对调节单个自分泌环的两种蛋白质开发的。随后开发了针对EGFR和凋亡调节蛋白bcl-2的双特异性寡核苷酸。单个线性序列寡核苷酸的双特异性活性已显示具有疗效。为了进一步发展这种多特异性方法，我们现在提出一种分支反义化合物，同样具有多个结合位点活性（针对互补序列的mRNA）。活性寡核苷酸将连接到脂溶性主链上，这可能会增强靶向性以及细胞内进入、释放和活性。这样的结构还将允许定制这些分支形式，以包括针对与各种肿瘤类型生长相关的特定蛋白质的寡核苷酸。与反义寡核苷酸开发相关的问题包括膜溶解性和特异性靶向。通过设计这种分支形式的反义结构，可以保留（增加）多种活性，提高溶解性并增强递送。这种新制剂将包括几个与类脂主链共价结合并从其分支出来的反义寡核苷酸。延长的烃链将增加脂溶性，并允许寡核苷酸掺入纳米颗粒或脂质体衍生的递送载体中。这些纳米颗粒或脂质体微泡在照射到靶组织的超声波影响下破裂的趋势也可以增强寡核苷酸的特异性递送。
