The cancer secretome,current status and opportunities in the lung,breast and colorectal cancer context

Despite major improvements on the knowledge and clinical management, cancer is still a deadly disease. Novel biomarkers for better cancer detection, diagnosis and treatment prediction are urgently needed. Proteins secreted, shed or leaking from the cancer cell, collectively termed the cancer secretome, are promising biomarkers since they might be detectable in blood or other biofluids. Furthermore, the cancer secretome in part represents the tumor microenvironment that plays a key role in tumor promoting processes such as angiogenesis and invasion. The cancer secretome, sampled as conditioned medium from cell lines, tumor/tissue interstitial fluid or tumor proximal body fluids, can be studied comprehensively by nanoLC-MS/MS-based approaches. Here, we outline the importance of current cancer secretome research and describe the mass spectrometry-based analysis of the secretome. Further, we provide an overview of cancer secretome research with a focus on the three most common cancer types: lung, breast and colorectal cancer. We conclude that the cancer secretome research field is a young, but rapidly evolving research field. Up to now, the focus has mainly been on the discovery of novel promising secreted cancer biomarker proteins. An interesting finding that merits attention is that in cancer unconventional secretion, e.g. via vesicles, seems increased. Refinement of current approaches and methods and progress in clinical validation of the current findings are vital in order to move towards applications in cancer management. This article is part of a Special Issue entitled: An Updated Secretome.     

OSBPL2-disrupted pigs recapitulate dual features of human hearing loss and hypercholesterolaemia

Oxysterol binding protein like 2(OSBPL2), an important regulator in cellular lipid metabolism and transport, was identified as a novel deafness-causal gene in our previous work. To resemble the phenotypic features of OSBPL2 mutation in animal models and elucidate the potential genotypephenotype associations, the OSBPL2-disrupted Bama miniature(BM) pig model was constructed using CRISPR/Cas9-mediated gene editing, somatic cell nuclear transfer(SCNT) and embryo transplantation approaches, and then subjected to phenotypic characterization of auditory function and serum lipid profiles. The OSBPL2-disrupted pigs displayed progressive hearing loss(HL) with degeneration/apoptosis of cochlea hair cells(HCs) and morphological abnormalities in HC stereocilia, as well as hypercholesterolaemia. High-fat diet(HFD) feeding aggravated the development of HL and led to more severe hypercholesterolaemia. The dual phenotypes of progressive HL and hypercholesterolaemia resembled in OSBPL2-disrupted pigs confirmed the implication of OSBPL2 mutation in nonsydromic hearing loss(NSHL) and contributed to the potential linkage between auditory dysfunction and dyslipidaemia/hypercholesterolaemia.     

Knockdown of NOB1 expression by RNAi inhibits cellular proliferation and migration in human gliomas

NOB1 (NIN1/RPN12 binding protein 1 homolog), a ribosome assembly factor, is thought to be essential for the processing of the 20S pre-rRNA into the mature 18S rRNA. It is also reported to participate in proteasome biogenesis. However, the contribution of NOB1 gene dysfunction to the pathology of human diseases, such as gliomas, has not been addressed. Here, we detected expression levels of NOB1 mRNA in U251, U87, U373, and A172 cells by quantitative real-time PCR. To analyze the expression levels of NOB1 protein in glioma tissues, we performed immunohistochemistry on 56 pathologically confirmed glioma samples (7 Grade I cases, 19 Grade II cases, 16 Grade III cases, and 14 Grade IV cases). A recombinant lentivirus expressing NOB1 short hairpin RNA (shNOB1) was constructed and infected into U251 and U87-MG human glioma cells. We found that NOB1 mRNA was expressed in all four cell lines. The expression level of the NOB1 protein was significantly higher in high-grade gliomas than in low-grade gliomas. Knockdown of the NOB1 gene resulted in suppression of the proliferation and the colony-forming abilities of U251 and U87-MG cells, cell cycle arrest during the G₀/G₁ phase, and a significant enhancement of cell apoptosis. In addition, cell migration was significantly suppressed in U251 and U87-MG cells that were infected with the shNOB1-expressing lentivirus. These results suggest that NOB1 promotes glioma cell growth and migration and could be a candidate for molecular targeting during gene therapy treatments of glioma.     

Multiple polymorphisms within the PLCE1 are associated with esophageal cancer via promoting the gene expression in a Chinese Kazakh population

Although recent genome-wide association studies of esophageal squamous cell carcinoma (ESCC) identified a susceptibility locus in phospholipase C epsilon 1 (PLCE1) in Chinese Han populations, few studies further confirmed these findings in pure Kazakh population in which there are higher incidence and mortality of ESCC. Here, we investigated the potential associations between 19 SNPs of PLCE1 and susceptibility to ESCC in 222 cases and 326 controls from a pure ethnic population of Kazakh. Real-time PCR and immunohistochemistry were performed to detect the PLCE1 expression levels and evaluate their association with PLCE1 polymorphism. We found that only 4 SNPs (rs753724, rs11187842, rs2274223, and rs12263737) with moderate linkage disequilibrium (LD) confer significantly increased risk of ESCC, with the ORs ranging from 1.43 to 2.04, and there was a risk allele dose-dependent increase in ESCC risk (P-trend = 0.043). Especially, the risk effects of rs2274223 were more evident in poor differentiation and advanced clinical stages of Kazakh ESCC. Additionally, the significantly lowest PLCE1 mRNA expression was found in the KYSE-150 cell line having no risk alleles compared with other three cell lines having risk alleles, and the normal tissues of both homozygous mutant type of PLCE1 rs12263737 and rs2274223 had a higher PLCE1 staining score than that of homozygous wild type. Our findings suggested that genetic variants in PLCE1 might serve as candidate markers for Kazakh ESCC susceptibility, and these LD variants might influence ESCC risk individually and jointly by promoting the messenger RNA and protein expression of the gene.     

MEK1 promotes YAP and their interaction is critical for tumorigenesis in liver cancer

Mitogen-activated protein kinase kinase 1 (MAP2K1/MEK1) as well as Yes-associated protein (YAP), the downstream effector of Hippo signaling pathway, is linked to hepatocarcinogenesis. However, little is known about whether and how MEK1 interacts with YAP. In this study, we find that MEK1-YAP interaction is critical for liver cancer cell proliferation and maintenance of transformed phenotypes both in vitro and in vivo. Moreover, MEK1 and YAP proteins are closely correlated in human liver cancer samples. Mechanistically, inhibition of MEK1 by both PD98059 and U0126 as well as RNAi reduces beta-transducin repeat containing E3 ubiquitin protein ligase (BTRC), which acts as a potential endogenous YAP protector.     

CYP26B1 promotes male germ cell differentiation by suppressing STRA8-dependent meiotic and STRA8-independent mitotic pathways

Germ cell sex is defined by factors derived from somatic cells. CYP26B1 is known to be a male sex-promoting factor that inactivates retinoic acid (RA) in somatic cells. In CYP26B1-null XY gonads, germ cells are exposed to a higher level of RA than in normal XY gonads and this activates Stra8 to induce meiosis while male-specific gene expression is suppressed. However, it is unknown whether meiotic entry by an elevated level of RA is responsible for the suppression of male-type gene expression. To address this question, we have generated Cyp26b1/Stra8 double knockout (dKO) embryos. We successfully suppressed the induction of meiosis in CYP26B1-null XY germ cells by removing the Stra8 gene. Concomitantly, we found that the male genetic program represented by the expression of NANOS2 and DNMT3L was totally rescued in about half of dKO germ cells, indicating that meiotic entry causes the suppression of male differentiation. However, half of the germ cells still failed to enter the appropriate male pathway in the dKO condition. Using microarray analyses together with immunohistochemistry, we found that KIT expression was accompanied by mitotic activation, but was canceled by inhibition of the RA signaling pathway. Taken together, we conclude that inhibition of RA is one of the essential factors to promote male germ cell differentiation, and that CYP26B1 suppresses two distinct genetic programs induced by RA: a Stra8-dependent meiotic pathway, and a Stra8-independent mitotic pathway.     

Cellular prostatic acid phosphatase,a PTEN-functional homologue in prostate epithelia,functions as a prostate-specific tumor suppressor

The inactivation of tumor suppressor genes (TSGs) plays a vital role in the progression of human cancers. Nevertheless, those ubiquitous TSGs have been shown with limited roles in various stages of diverse carcinogenesis. Investigation on identifying unique TSG, especially for early stage of carcinogenesis, is imperative. As such, the search for organ-specific TSGs has emerged as a major strategy in cancer research. Prostate cancer (PCa) has the highest incidence in solid tumors in US males. Cellular prostatic acid phosphatase (cPAcP) is a prostate-specific differentiation antigen. Despite intensive studies over the past several decades on PAcP as a PCa biomarker, the role of cPAcP as a PCa-specific tumor suppressor has only recently been emerged and validated. The mechanism underlying the pivotal role of cPAcP as a prostate-specific TSG is, in part, due to its function as a protein tyrosine phosphatase (PTP) as well as a phosphoinositide phosphatase (PIP), an apparent functional homologue to phosphatase and tensin homolog (PTEN) in PCa cells. This review is focused on discussing the function of this authentic prostate-specific tumor suppressor and the mechanism behind the loss of cPAcP expression leading to prostate carcinogenesis. We review other phosphatases' roles as TSGs which regulate oncogenic PI3K signaling in PCa and discuss the functional similarity between cPAcP and PTEN in prostate carcinogenesis.     

Cdkl在浆液性卵巢癌中的表达及其与化疗耐药及预后的相关性

目的：卵巢癌是女性生殖致死率最高的恶性肿瘤。Cdkl作为细胞周期依赖性激酶中的核心分子,对肿瘤细胞的发生发展具有重要作用。本文旨在探讨Cdkl蛋白在上皮性浆液性卵巢癌中的表达情况,并分析其表达水平与患者临床病理特征、化疗反应及预后之间的关系。方法：采用免疫组化法检测68例浆液性卵巢癌中Cdkl蛋白的表达情况,并结合临床资料分析Cdkl蛋白的表达水平在浆液性卵巢癌患者中的意义。结果：Cdkl在浆液性卵巢癌患者中具有不同程度的阳性表达,其表达水平和患者的年龄、病理分化程度、淋巴结转移情况及临床分期无明显相关性（P〉0．05）,但是其高表达与化疗耐药明显相关（P=0．040）。化疗耐药的卵巢癌患者中Cdkl的蛋白表达明显高于化疗敏感组,并且生存分析发现,高表达Cdkl的患者预后较差。结论：本研究证明Cdkl在浆液性卵巢癌中有较高表达,并且Cdkl的表达与卵巢癌化疗后复发有关,高的Cdkl表达预示着较差的预后。Cdkl可能是晚期浆液性卵巢癌治疗的新靶点。     

Cdk1在浆液性卵巢癌中的表达及其与化疗耐药及预后的相关性

目的:卵巢癌是女性生殖致死率最高的恶性肿瘤。Cdk1作为细胞周期依赖性激酶中的核心分子,对肿瘤细胞的发生发展具有重要作用。本文旨在探讨Cdk1蛋白在上皮性浆液性卵巢癌中的表达情况,并分析其表达水平与患者临床病理特征、化疗反应及预后之间的关系。方法:采用免疫组化法检测68例浆液性卵巢癌中Cdk1蛋白的表达情况,并结合临床资料分析Cdk1蛋白的表达水平在浆液性卵巢癌患者中的意义。结果:Cdk1在浆液性卵巢癌患者中具有不同程度的阳性表达,其表达水平和患者的年龄、病理分化程度、淋巴结转移情况及临床分期无明显相关性(P0.05),但是其高表达与化疗耐药明显相关(P=0.040)。化疗耐药的卵巢癌患者中Cdk1的蛋白表达明显高于化疗敏感组,并且生存分析发现,高表达Cdk1的患者预后较差。结论:本研究证明Cdk1在浆液性卵巢癌中有较高表达,并且Cdk1的表达与卵巢癌化疗后复发有关,高的Cdk1表达预示着较差的预后。Cdk1可能是晚期浆液性卵巢癌治疗的新靶点。