单克隆抗体靶向制剂的研究进展

本文综述了制备单克隆抗体免疫偶合物的三种方法,即抗体与药物直接交联的方法,药物通过小分子与抗体连接的戊二醛法、顺乌头酸酐法、活性酯法、Ｎ－琥珀酰胺基－３－（２－吡啶基二硫）丙酸法（ＳＰＤＰ法）、腙衍生物法和肽键连接等方法,以及用大分子做载体的交联方法,并介绍了葡聚糖、聚谷氨酸、聚赖氨酸和聚合多肽作载体的性质和应用情况。     

Crystal structure of the yeast Sac1: implications for its phosphoinositide phosphatase function

Sac family phosphoinositide (PI) phosphatases are an essential family of CX₅R(T/S)‐based enzymes, involved in numerous aspects of cellular function such as PI homeostasis, cellular signalling, and membrane trafficking. Genetic deletions of several Sac family members result in lethality in animal models and mutations of the Sac3 gene have been found in human hereditary diseases. In this study, we report the crystal structure of a founding member of this family, the Sac phosphatase domain of yeast Sac1. The 2.0 Å resolution structure shows that the Sac domain comprises of two closely packed sub‐domains, a novel N‐terminal sub‐domain and the PI phosphatase catalytic sub‐domain. The structure further shows a striking conformation of the catalytic P‐loop and a large positively charged groove at the catalytic site. These findings suggest an unusual mechanism for its dephosphorylation function. Homology structural modeling of human Fig4/Sac3 allows the mapping of several disease‐related mutations and provides a framework for the understanding of the molecular mechanisms of human diseases.     

Snail mRNA及其蛋白在乳腺癌中的表达研究

目的观察Snail蛋白及mRNA在人乳腺癌组织中的表达及其与临床病理特征的关系,并探讨它在乳腺癌发生、发展及转移中的作用。方法应用SP免疫组织化学和原位分子杂交方法检测Snail蛋白和Snail mRNA在70例乳腺浸润性导管癌、30例乳腺导管内癌、30例乳腺单纯性增生组织中的表达。结果①70例乳腺癌中,Snail蛋白和Snail mRNA阳性率分别为87.2%(61/70)、81.4%(57/70),分别高于乳腺导管内癌组织53.3%(16/30)、46.7%(14/30)和乳腺单纯性增生组织26.7%(8/30)、23.3%(7/30),三者相比有统计学意义(χ2=36.4,P<0.01;χ2=32.4,P<0.01)。②Snail蛋白和SnailmRNA在有淋巴结转移组中的阳性率为97.6%(40/41)、95.1%(39/41),无转移组阳性率为72.4%(21/29)、62.1%(18/29),两者相比有统计学意义(χ2=8.29,P<0.01);组织学分级Ⅲ级组明显高于Ⅰ、Ⅱ级组表达,但无统计学意义(χ2=0.72,P>0.05;χ2=0.98,P>0.05)。③Snail蛋白与Snail mRNA的表达与年龄、肿瘤大小均无关(P>0.05)。结论 Snail蛋白与Snail mRNA的表达呈正相关,与乳腺癌的发生发展、淋巴结转移密切相关,可作为判断乳腺癌预后、转移的生物学标志。     

Circular RNA circCCNB1 inhibits the migration and invasion of nasopharyngeal carcinoma through binding and stabilizing TJP1 mRNA

Science China Life Sciences - Nasopharyngeal carcinoma (NPC) is a malignant tumor that usually occurs in people from Southeast Asia and Southern China. NPC is prone to migration and invasion,...     

Surrogate production of genome-edited sperm from a different subfamily by spermatogonial stem cell transplantation

The surrogate reproduction technique, such as inter-specific spermatogonial stem cells (SSCs) transplantation (SSCT), provides a powerful tool for production of gametes derived from endangered species or those with desirable traits. However, generation of genome-edited gametes from a different species or production of gametes from a phylogenetically distant species such as from a different subfamily, by SSCT, has not succeeded. Here, using two small cyprinid fishes from different subfamilies, Chinese rare minnow (gobiocypris rarus, for brief: Gr) and zebrafish (danio rerio), we successfully obtained Gr-derived genome-edited sperm in zebrafish by an optimized SSCT procedure. The transplanted Gr SSCs supported the host gonadal development and underwent normal spermatogenesis, resulting in a reconstructed fertile testis containing Gr spermatids and zebrafish testicular somatic cells. Interestingly, the surrogate spermatozoa resembled those of host zebrafish but not donor Gr in morphology and swimming behavior. When pou5f3 and chd knockout Gr SSCs were transplanted, Gr-derived genome-edited sperm was successfully produced in zebrafish. This is the first report demonstrating surrogate production of gametes from a different subfamily by SSCT, and surrogate production of genome-edited gametes from another species as well. This method is feasible to be applied to future breeding of commercial fish and livestock.

     

Acid-activatable prodrug nanogels for efficient intracellular doxorubicin release

Endosomal pH-activatable doxorubicin (DOX) prodrug nanogels were designed, prepared, and investigated for triggered intracellular drug release in cancer cells. DOX prodrugs with drug grafting contents of 3.9, 5.7, and 11.7 wt % (denoted as prodrugs 1, 2, and 3, respectively) were conveniently obtained by sequential treatment of poly(ethylene glycol)-b-poly(2-hydroxyethyl methacrylate-co-ethyl glycinate methacrylamide) (PEG-b-P(HEMA-co-EGMA)) copolymers with hydrazine and doxorubicin hydrochloride. Notably, prodrugs 1, 2, and 3 formed monodispersed nanogels with average sizes of 114.4, 75.3, and 66.3 nm, respectively, in phosphate buffer (PB, 10 mM, pH 7.4). The in vitro release results showed that DOX was released rapidly and nearly quantitatively from DOX prodrug nanogels at endosomal pH and 37 °C in 48 h, whereas only a minor amount (ca. 20% or less) of drug was released at pH 7.4 under otherwise the same conditions. Confocal laser scanning microscope (CLSM) observations revealed that DOX prodrug nanogels delivered and released DOX into the cytosols as well as cell nuclei of RAW 264.7 cells following 24 h incubation. MTT assays demonstrated that prodrug 3 had pronounced cytotoxic effects to tumor cells following 72 h incubation with IC(50) data determined to be 2.0 and 3.4 μg DOX equiv/mL for RAW 264.7 and MCF-7 tumor cells, respectively. The corresponding polymer carrier, PEG-b-P(HEMA-co-GMA-hydrazide), was shown to be nontoxic up to a tested concentration of 1.32 mg/mL. These endosomal pH-activatable DOX prodrug nanogels uniquely combining features of water-soluble macromolecular prodrugs and nanogels offer a promising platform for targeted cancer therapy.     

Galactose-decorated cross-linked biodegradable poly(ethylene glycol)-b-poly(ε-caprolactone) block copolymer micelles for enhanced hepatoma-targeting delivery of paclitaxel

The inferior in vivo stability of micellar drugs has been a prime challenge for their application in targeted drug delivery. Here we report on novel galactose-decorated covalently cross-linked biodegradable micelles based on photo-cross-linkable poly(ethylene glycol)-b-poly(acryloyl carbonate)-b-poly(ε-caprolactone) (PEG-PAC-PCL) and galactose-conjugated PEG-PCL (Gal-PEG-PCL) copolymers for enhanced hepatoma-targeting delivery of paclitaxel (PTX). The molecular weight of PEG in Gal-PEG-PCL was higher than that in PEG-PAC-PCL, thereby fully exposing Gal ligands at the micellar surface. These micelles, either with or without loading of PTX, were readily cross-linked by UV irradiation to afford micelles with small sizes (ca. 79-94 nm) and enhanced stability. The in vitro release studies confirmed that drug release from cross-linked micelles was significantly inhibited. Interestingly, MTT assays showed that Gal-decorated PTX-loaded cross-linked micelles retained a high antitumor activity in HepG2 cells, which was much more effective than PTX-loaded cross-linked micelles without Gal ligands and comparable to Gal-decorated PTX-loaded non-cross-linked micelles. Remarkably, the preliminary in vivo antitumor efficacy studies in SMMC-7721 tumor (human hepatoma)-bearing nude mice revealed that Gal-decorated PTX-loaded cross-linked micelles inhibited the growth of the human hepatoma more effectively than PTX-loaded cross-linked micelles as well as Gal-decorated PTX-loaded non-cross-linked micelles. These results indicate that Gal-decorated cross-linked PEG-PCL micelles have great potential in liver tumor-targeted chemotherapy.     

Fanconi anemia complementation group A (FANCA) protein has intrinsic affinity for nucleic acids with preference for single-stranded forms

The Fanconi anemia complementation group A (FANCA) gene is one of 15 disease-causing genes and has been found to be mutated in ～60% of Fanconi anemia patients. Using purified protein, we report that human FANCA has intrinsic affinity for nucleic acids. FANCA binds to both single-stranded (ssDNA) and double-stranded (dsDNA) DNAs; however, its affinity for ssDNA is significantly higher than for dsDNA in an electrophoretic mobility shift assay. FANCA also binds to RNA with an intriguingly higher affinity than its DNA counterpart. FANCA requires a certain length of nucleic acids for optimal binding. Using DNA and RNA ladders, we determined that the minimum number of nucleotides required for FANCA recognition is ～30 for both DNA and RNA. By testing the affinity between FANCA and a variety of DNA structures, we found that a 5'-flap or 5'-tail on DNA facilitates its interaction with FANCA. A patient-derived FANCA truncation mutant (Q772X) has diminished affinity for both DNA and RNA. In contrast, the complementing C-terminal fragment of Q772X, C772-1455, retains the differentiated nucleic acid-binding activity (RNA > ssDNA > dsDNA), indicating that the nucleic acid-binding domain of FANCA is located primarily at its C terminus, where most disease-causing mutations are found.