Saposin C stimulates growth and invasion,activates p42/44 and SAPK/JNK signaling pathways of MAPK and upregulates uPA/uPAR expression in prostate cancer and stromal cells

Aim:To determine the effect of saposin C (a known trophic domain of prosaposin) on proliferation,migration and invasion,as well as its effect on the expression of urokinase plasmonogen activator (uPA),its receptor (uPAR) and matrix metalloproteinases (MMP)-2 and -9 in normal and malignant prostate cells.In addition,we tested whether saposin C can activate p42/44 and stress-activated protein kinase/c-Jun NH_2-terminal kinase (SAPK/JNK) signal transduction pathways of the mitogen-activated protein kinase (MAPK) superfamily.Methods:We employed West- ern blot analysis,phospho-specific antibodies,cell proliferation assay,reverse transcriptase-polymerase chain reaction, in vitro kinase assays and migration and invasion to determine the effect of saposin C on various biological behaviors of prostate stromal and cancer cells.Results:Saposin C,in a cell type-specific manner,upregulates uPA/uPAR and immediate early gene c-Jun expression,stimulates cell proliferation,migration and invasion and activates p42/44 and SAPK/JNK MAPK pathways in prostate stromal and cancer cells.Normal prostate epithelial cells were not responsive to saposin C treatment in the above studies.Conclusion:Saposin C functions as a multipotential modulator of diverse biological activities in prostate cancer and stromal cells.These results strongly suggest that saposin C functions as a potent growth factor for prostatic cells and may contribute to prostate carcinogenesis and/or the development of hormone-refractory prostate cancer.

蛋白脂质微粒体Saposin C-dops能增强小鼠免疫功能

目的:研究新型抗肿瘤药Saposin C-dops对小鼠免疫功能的影响。方法:采用实效药量及其10倍药量的Saposin C-dops给雌性B6小鼠进行连续7d腹腔注射给药后,检测小鼠脾脏中与肿瘤免疫相关的免疫细胞、血清中的细胞因子和IgG含量的变化,从而判断其在正常药量和超量情况下对健康小鼠免疫力的影响。结果:Saposin C-dops在正常用药量情况下对小鼠免疫功能有显著激活效应,这种激活效应不是剂量依赖的,而且在超量应用的情况下对小鼠免疫功能不产生负面影响。结论:Sapo-sin C-dops具有免疫激活剂的作用,能增强小鼠的免疫功能。

Saposin C抑制雄激素受体的多泛素化以及在蛋白酶体中的降解(英文)

本研究旨在证实鞘脂活化蛋白C(saposin C)对雄激素受体(AR)多泛素化降解的影响及其机制.通过将真核表达载体saposin C转染LNCaP细胞,发现saposin C上调AR的蛋白水平和转录激活活性.进一步将野生型和突变型泛素质粒Ubwt和UbK48R分别与saposin C共转染LNCaP细胞发现,saposin C能够促进AR蛋白的单泛素化形式的稳定性,抑制AR的多泛素化修饰及其在蛋白酶体中的降解.其分子机制是saposin C、Ub和AR三者形成复合体,抑制了AR的进一步多泛素化过程.同时还发现,在这一机制中,细胞内低浓度的雄激素(0.1 nmol/L)与saposin C具有协同作用.

Saposin C促进PC3细胞p27^(KIP1)蛋白泛素化降解的研究

目的:探讨Saposin C促进PC3细胞抑癌基因p27KIP1蛋白泛素化降解,刺激细胞增殖,以及与PI3K/AKT信号通路的关系。方法:利用含有Saposin C的真核表达载体转染PC3细胞,检测Saposin C对PC3细胞Skp2、抑癌基因p27KIP1蛋白水平的调节以及对细胞增殖的影响。结果:Saposin C通过激活PI3K/AKT信号途径上调细胞内Skp2的蛋白含量,下调抑癌基因p27KIP1的蛋白水平,其机制是加速p27KIP1的蛋白降解,促进PC3细胞增殖。结论:Saposin C在PC3细胞中通过激活PI3K/AKT信号途径促进抑癌基因p27KIP1的蛋白泛素化降解,刺激细胞增殖。

Ectopic expression of neurotrophic peptide derived from saposin C increases proliferation and upregulates androgen receptor expression and transcriptional activity in human prostate cancer cells

Aim： To determine the effects of the functional domain of saposin C （neurotrophic peptide [NP]） on androgen receptor （AR） expression and transcriptional activity. Methods： We constructed DNA vectors expressing NP or a chimeric peptide of the viral TAT transduction domain and NP （TAT-NP） using gene cloning technology. The effects of ectopic expression of NP or TAT-NP on cell growth were examined by 3-（4, 5-dimethylthiazol-2-yl）-2, 5-diphenyl-2H-tetrazolium bromide （MTT） assay. Reverse transcription-polymerase chain reaction （RT-PCR）, Western blot, transient transfection and reporter gene assays were used to determine the effects of NP on AR expression and activation. Results： NP stimulated proliferation of androgen responsive LNCaP cells in the absence of androgens. RT-PCR and Western blot analyses showed that ectopic expression of NP resulted in induction of AR gene expression, and that the NP-stimulated expression of AR could be synergistically enhanced in the presence of androgens. Furthermore, reporter gene assay results showed that NP could enhance AR transactivation by increasing androgen-inducible gene reporter activity. Conclusion： We provided evidence that ectopic expression of saposin C-originated NP could upregulate AR gene expression and activate the AR transcriptional function in an androgen-independent manner in prostate cancer cells.

Targeting of elevated cell surface phosphatidylserine with saposin C-dioleoylphosphatidylserine nanodrug as individual or combination therapy for pancreatic cancer

Pancreatic cancer is one of the deadliest of cancers with a five-year survival of roughly 8%.Current therapies are:surgery,radiation and chemotherapy.Surgery is curative only if the cancer is caught very early,which is rare,and the latter two modalities are only marginally effective and have significant side effects.We have developed a nanosome comprised of the lysosomal protein,saposin C(SapC)and the acidic phospholipid,dioleoylphosphatidylserine(DOPS).In the acidic tumor microenvironment,this molecule,SapC-DOPS,targets the phosphatidylserine cancer-biomarker which is predominantly elevated on the surface of cancer cells.Importantly,SapC-DOPS can selectively target pancreatic tumors and metastases.Furthermore,SapC-DOPS has exhibited an impressive safety profile with only a few minor side effects in both preclinical experiments and in phase I clinical trials.With the dismal outcomes for pancreatic cancer there is an urgent need for better treatments and SapC-DOPS is a good candidate for addition to the oncologist’s toolbox.

鞘脂激活蛋白C通过上调雄激素受体的表达与活性促进LNCaP细胞的增殖

目的构建含有鞘脂激活蛋白C(Saposin C)的真核表达载体,探讨Saposin C在前列腺癌雄激素依赖性前列腺细胞(LNCaP)中对雄激素受体(AR)及细胞增殖的影响。方法通过cDNA法构建含有TAT和Saposin C的真核表达载体,并将其转染至前列腺癌LNCaP细胞。通过MTS、RT-PCR、Western blot等实验,分别检测TAT-Saposin C与Saposin C的AR基因表达与其转录激活功能,以及对前列腺癌细胞增殖的影响。结果在不依赖雄激素的情况下,Saposin C能够上调AR与PSA基因mRNA和蛋白质水平的表达,增加AR的转录激活活性,刺激LNCaP细胞的增殖。结论 Saposin C通过雄激素非依赖性上调AR的表达与转录激活活性,促进LNCaP细胞的增殖。