SF3B4 Depletion Retards the Growth of A549 Non-Small Cell Lung Cancer Cells via UBE4B-Mediated Regulation of p53/p21 and p27 Expression

Splicing factor B subunit 4 (SF3B4), a component of the U2-pre-mRNA spliceosomal complex, contributes to tumorigenesis in several types of tumors. However, the oncogenic potential of SF3B4 in lung cancer has not yet been determined. The in vivo expression profiles of SF3B4 in non-small cell lung cancer (NSCLC) from publicly available data revealed a significant increase in SF3B4 expression in tumor tissues compared to that in normal tissues. The impact of SF3B4 deletion on the growth of NSCLC cells was determined using a siRNA strategy in A549 lung adenocarcinoma cells. SF3B4 silencing resulted in marked retardation of the A549 cell proliferation, accompanied by the accumulation of cells at the G0/G1 phase and increased expression of p27, p21, and p53. Double knockdown of SF3B4 and p53 resulted in the restoration of p21 expression and partial recovery of cell proliferation, indicating that the p53/p21 axis is involved, at least in part, in the SF3B4-mediated regulation of A549 cell proliferation. We also provided ubiquitination factor E4B (UBE4B) is essential for p53 accumulation after SF3B4 depletion based on followings. First, co-immunoprecipitation showed that SF3B4 interacts with UBE4B. Furthermore, UBE4B levels were decreased by SF3B4 depletion. UBE4B depletion, in turn, reproduced the outcome of SF3B4 depletion, including reduction of polyubiquitinated p53 levels, subsequent induction of p53/p21 and p27, and proliferation retardation. Collectively, our findings indicate the important role of SF3B4 in the regulation of A549 cell proliferation through the UBE4B/p53/p21 axis and p27, implicating the therapeutic strategies for NSCLC targeting SF3B4 and UBE4B.

Hypercompact adenine base editors based on transposase B guided by engineered RNA

Transposon-associated transposase B (TnpB) is deemed an ancestral protein for type V, Cas12 family members, and the closest ancestor to UnCas12f1. Previously, we reported a set of engineered guide RNAs supporting high indel efficiency for Cas12f1 in human cells. Here we suggest a new technology whereby the engineered guide RNAs also manifest high-efficiency programmable endonuclease activity for TnpB. We have termed this technology TaRGET (TnpB-augment RNA-based Genome Editing Technology). Having this feature in mind, we established TnpB-based adenine base editors (ABEs). A Tad-Tad mutant (V106W, D108Q) dimer fused to the C terminus of dTnpB (D354A) showed the highest levels of A-to-G conversion. The limited targetable sites for TaRGET-ABE were expanded with engineered variants of TnpB or optimized deaminases. Delivery of TaRGET-ABE also ensured potent A-to-G conversion rates in mammalian genomes. Collectively, the TaRGET-ABE will contribute to improving precise genome-editing tools that can be delivered by adeno-associated viruses, thereby harnessing the development of clustered regularly interspaced short palindromic repeats (CRISPR)-based gene therapy.

Defect in cytosolic Neu2 sialidase abrogates lipid metabolism and impairs muscle function in vivo

Sialic acid (SA) is present in glycoconjugates and important in cell–cell recognition, cell adhesion, and cell growth and as a receptor. Among the four mammalian sialidases, cytosolic NEU2 has a pivotal role in muscle and neuronal differentiation in vitro. However, its biological functions in vivo remain unclear due to its very low expression in humans. However, the presence of cytoplasmic glycoproteins, gangliosides, and lectins involved in cellular metabolism and glycan recognition has suggested the functional importance of cytosolic Neu2 sialidases. We generated a Neu2 knockout mouse model via CRISPR/Cas9-mediated genome engineering and analyzed the offspring littermates at different ages to investigate the in vivo function of cytosolic Neu2 sialidase. Surprisingly, knocking out the Neu2 gene in vivo abrogated overall lipid metabolism, impairing motor function and leading to diabetes. Consistent with these results, Neu2 knockout led to alterations in sialylated glycoproteins involved in lipid metabolism and muscle function, as shown by glycoproteomics analysis.

Efficient CRISPR editing with a hypercompact Cas12f1 and engineered guide RNAs delivered by adeno-associated virus

Gene therapy would benefit from a miniature CRISPR system that fits into the small adeno-associated virus (AAV) genome and has high cleavage activity and specificity in eukaryotic cells. One of the most compact CRISPR-associated nucleases yet discovered is the archaeal Un1Cas12f1. However, Un1Cas12f1 and its variants have very low activity in eukaryotic cells. In the present study, we redesigned the natural guide RNA of Un1Cas12f1 at five sites: the 5' terminus of the trans-activating CRISPR RNA (tracrRNA), the tracrRNA-crRNA complementary region, a penta(uridinylate) sequence, the 3' terminus of the crRNA and a disordered stem 2 region in the tracrRNA. These optimizations synergistically increased the average indel frequency by 867-fold. The optimized Un1Cas12f1 system enabled efficient, specific genome editing in human cells when delivered by plasmid vectors, PCR amplicons and AAV. As Un1Cas12f1 cleaves outside the protospacer, it can be used to create large deletions efficiently. The engineered Un1Cas12f1 system showed efficiency comparable to that of SpCas9 and specificity similar to that of AsCas12a.

Depletion of ST6GALNACIII retards A549 non-small cell lung cancer cell proliferation by downregulating transferrin receptor protein 1 expression

Alterations in sialylation of terminal residues of glycoproteins have been implicated in forming tumor-associated glycans. ST6GALNAC transfers sialyl moiety to N-acetylgalactosamine residue via α2,6 linkage. Although the oncogenic characteristics of ST6GALNACI or II have been demonstrated in various cancer cells, the impact of ST6GALNACIII on tumor progression remains undefined. In this study, we evaluated the effect of ST6GALNACIII knockdown on the growth of A549 non-small cell lung cancer cells. ST6GALNACIII depletion resulted in significant retardation in growth of A549 cells under various culture conditions, including collagen-supported 3D culture and anchorage-independent soft agar culture conditions. Liquid chromatography with tandem mass spectrometry revealed that two glycopeptides of transferrin receptor protein 1 (TFR1) containing N-acetylhexosamine-sialic acid were not detected in ST6GALNACIII-depleted A549 cells compared with control cells. Subsequent lectin binding assay, western blotting, and real-time RT-PCR indicated that TFR1 sialylation was not significantly changed, but TFR1 protein and mRNA expressions were decreased after ST6GALNACIII knockdown. However, cell growth retardation by ST6GALNACIII knockdown was partially rescued by TFR1 overexpression. Additionally, TFR1 mRNA degradation was accelerated following ST6GALNACIII knockdown with concomitant reduction in mRNA levels of iron regulatory protein 1 and 2, the upstream regulators of TFR1 mRNA stability. Therefore, our results indicated an important role of ST6GALNACIII in promoting A549 cell growth through quantitative regulation of TFR1 expression and provided therapeutic implications for ST6GALNACIII targeting in tumor growth suppression in vivo.

One-step genotyping method in CRISPR based on short inner primer-assisted, tetra primer-paired amplifications

Base editors and prime editors induce precise DNA modifications over one or several nucleotides in eukaryotic cells. The T7E1 assay has been widely adopted for the assessment of genome editing, but it has several limitations in the applications for prime editing and base editing due to low sensitivity, inaccuracy and additional disadvantages. Here, we propose a short inner primer-assisted, tetra primer-paired amplification (SIPATA) method as an alternative to T7E1 analysis. SIPATA is a PCR-based method in which two long outer and two short (15 nt) inner primers are used for the amplification of a specific genotype in the presence of Hot start-Taq. One of the inner primers carries a 3'-terminally wild-type nucleotide sequence, and the other carries a post-editing sequence. Under optimized conditions, SIPATA enabled sensitive and accurate genotyping of single-nucleotide conversions by base editors and prime editors. Furthermore, SIPATA could be applied to trace low levels of DNA modifications achieved by HDR-mediated gene correction or chimerism during the generation of model animals. Multiplexed genotyping was also possible without compromising those multifaceted analytical advantages of SIPATA. Our findings demonstrate that SIPATA offers a robust, fast and sensitive genotyping platform for single-nucleotide variations in a variety of CRISPR applications.

Unbiased investigation of specificities of prime editing systems in human cells

Prime editors (PEs) enable targeted precise editing, including the generation of substitutions, insertions and deletions, in eukaryotic genomes. However, their genome-wide specificity has not been explored. Here, we developed Nickase-based Digenome-seq (nDigenome-seq), an in vitro assay that uses whole-genome sequencing to identify single-strand breaks induced by CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 (CRISPR-associated protein 9) nickase. We used nDigenome-seq to screen for potential genome-wide off-target sites of Cas9 H840A nickase, a PE component, targeted to nine human genomic sites. Then, using targeted amplicon sequencing of off-target candidates identified by nDigenome-seq, we showed that only five off-target sites showed detectable PE-induced modifications in cells, at frequencies ranging from 0.1 to 1.9%, suggesting that PEs provide a highly specific method of precise genome editing. We also found that PE specificity in human cells could be further improved by incorporating mutations from engineered Cas9 variants, particularly eSpCas9 and Sniper Cas9, into PE.

Highly efficient and safe genome editing by CRISPR-Cas12a using CRISPR RNA with a ribosyl-2'-O-methylated uridinylate-rich 3'-overhang in mouse zygotes

The CRISPR-Cas12a system has been developed to harness highly specific genome editing in eukaryotic cells. Given the relatively small sizes of Cas12a genes, the system has been suggested to be most applicable to gene therapy using AAV vector delivery. Previously, we reported that a U-rich crRNA enabled highly efficient genome editing by the CRISPR-Cas12a system in eukaryotic cells. In this study, we introduced methoxyl modifications at C2 in riboses in the U-rich 3'-overhang of crRNA. When mixed with Cas12a effector proteins, the ribosyl-2'-O-methylated (2-OM) U-rich crRNA enabled improvement of dsDNA digestibility. Moreover, the chemically modified U-rich crRNA achieved very safe and highly specific genome editing in murine zygotes. The engineered CRISPR-Cas12a system is expected to facilitate the generation of various animal models. Moreover, the engineered crRNA was evaluated to further improve a CRISPR genome editing toolset.

Selective Identification of α-Galactosyl Epitopes in N-Glycoproteins Using Characteristic Fragment Ions from Higher-Energy Collisional Dissociation

The α-galactosyl epitope is a terminal N-glycan moiety of glycoproteins found in mammals except in humans, and thus, it is recognized as an antigen that provokes an immunogenic response in humans. Accordingly, it is necessary to analyze the α-galactosyl structure in biopharmaceuticals or organ transplants. Due to an identical glycan composition and molecular mass between α-galactosyl N-glycans and hybrid/high-mannose-type N-glycans, it is challenging to characterize α-galactosyl epitopes in N-glycoproteins using mass spectrometry. Here, we describe a method to identify α-galactosyl N-glycopeptides in mice glycoproteins using liquid chromatography with tandem mass spectrometry with higher-energy collisional dissociation (HCD). The first measure was an absence of [Y_HM] ion peaks in the HCD spectra, which was exclusively observed in hybrid and/or high-mannose-type N-glycopeptides. The second complementary criterion was the ratio of an m/z 528.19 (Hex₂HexNAc₁) ion to m/z 366.14 (Hex₁HexNAc₁) ion (I_m/z528/I_m/z366). The measure of [I_m/z528/I_m/z366 > 0.3] enabled a clear-cut determination of α-galactosyl N-glycopeptides with high accuracy. In Ggta1 knockout mice, we could not find any α-galactosyl N-glycoproteins identified in WT mice plasma. Using this method, we could screen for α-galactosyl N-glycoproteins from mice spleen, lungs, and plasma samples in a highly sensitive and specific manner. Conclusively, we suggest that this method will provide a robust analytical tool for determination of α-galactosyl epitopes in pharmaceuticals and complex biological samples.

Machine Learning Classifies Core and Outer Fucosylation of N-Glycoproteins Using Mass Spectrometry

Protein glycosylation is known to be involved in biological progresses such as cell recognition, growth, differentiation, and apoptosis. Fucosylation of glycoproteins plays an important role for structural stability and function of N-linked glycoproteins. Although many of biological and clinical studies of protein fucosylation by fucosyltransferases has been reported, structural classification of fucosylated N-glycoproteins such as core or outer isoforms remains a challenge. Here, we report for the first time the classification of N-glycopeptides as core- and outer-fucosylated types using tandem mass spectrometry (MS/MS) and machine learning algorithms such as the deep neural network (DNN) and support vector machine (SVM). Training and test sets of more than 800 MS/MS spectra of N-glycopeptides from the immunoglobulin gamma and alpha 1-acid-glycoprotein standards were selected for classification of the fucosylation types using supervised learning models. The best-performing model had an accuracy of more than 99% against manual characterization and area under the curve values greater than 0.99, which were calculated by probability scores from target and decoy datasets. Finally, this model was applied to classify fucosylated N-glycoproteins from human plasma. A total of 82N-glycopeptides, with 54 core-, 24 outer-, and 4 dual-fucosylation types derived from 54 glycoproteins, were commonly classified as the same type in both the DNN and SVM. Specifically, outer fucosylation was dominant in tri- and tetra-antennary N-glycopeptides, while core fucosylation was dominant in the mono-, bi-antennary and hybrid types of N-glycoproteins in human plasma. Thus, the machine learning methods can be combined with MS/MS to distinguish between different isoforms of fucosylated N-glycopeptides.

Recent advances in the CRISPR genome editing tool set

Genome editing took a dramatic turn with the development of the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated proteins (Cas) system. The CRISPR-Cas system is functionally divided into classes 1 and 2 according to the composition of the effector genes. Class 2 consists of a single effector nuclease, and routine practice of genome editing has been achieved by the development of the Class 2 CRISPR-Cas system, which includes the type II, V, and VI CRISPR-Cas systems. Types II and V can be used for DNA editing, while type VI is employed for RNA editing. CRISPR techniques induce both qualitative and quantitative alterations in gene expression via the double-stranded breakage (DSB) repair pathway, base editing, transposase-dependent DNA integration, and gene regulation using the CRISPR-dCas or type VI CRISPR system. Despite significant technical improvements, technical challenges should be further addressed, including insufficient indel and HDR efficiency, off-target activity, the large size of Cas, PAM restrictions, and immune responses. If sophisticatedly refined, CRISPR technology will harness the process of DNA rewriting, which has potential applications in therapeutics, diagnostics, and biotechnology.

Improving CRISPR Genome Editing by Engineering Guide RNAs

CRISPR technology is a two-component gene editing system in which the effector protein induces genetic alterations with the aid of a gene targeting guide RNA. Guide RNA can be produced through chemical synthesis, in vitro transcription, or intracellular transcription. Guide RNAs can be engineered to have chemical modifications, alterations in the spacer length, sequence modifications, fusion of RNA or DNA components, and incorporation of deoxynucleotides. Engineered guide RNA can improve genome editing efficiency and target specificity, regulation of biological toxicity, sensitive and specific molecular imaging, multiplexing, and editing flexibility. Therefore, engineered guide RNA will enable more specific, efficient, and safe gene editing, ultimately improving the clinical benefits of gene therapy.

Effect of BIS depletion on HSF1-dependent transcriptional activation in A549 non-small cell lung cancer cells

The expression of BCL-2 interacting cell death suppressor (BIS), an anti-stress or anti-apoptotic protein, has been shown to be regulated at the transcriptional level by heat shock factor 1 (HSF1) upon various stresses. Recently, HSF1 was also shown to bind to BIS, but the significance of these protein-protein interactions on HSF1 activity has not been fully defined. In the present study, we observed that complete depletion of BIS using a CRISPR/Cas9 system in A549 non-small cell lung cancer did not affect the induction of heat shock protein (HSP) 70 and HSP27 mRNAs under various stress conditions such as heat shock, proteotoxic stress, and oxidative stress. The lack of a functional association of BIS with HSF1 activity was also demonstrated by transient downregulation of BIS by siRNA in A549 and U87 glioblastoma cells. Endogenous BIS mRNA levels were significantly suppressed in BIS knockout (KO) A549 cells compared to BIS wild type (WT) A549 cells at the constitutive and inducible levels. The promoter activities of BIS and HSP70 as well as the degradation rate of BIS mRNA were not influenced by depletion of BIS. In addition, the expression levels of the mutant BIS construct, in which 14 bp were deleted as in BIS-KO A549 cells, were not different from those of the WT BIS construct, indicating that mRNA stability was not the mechanism for autoregulation of BIS. Our results suggested that BIS was not required for HSF1 activity, but was required for its own expression, which involved an HSF1-independent pathway.

Lectin from Sambucus sieboldiana abrogates the anoikis resistance of colon cancer cells conferred by N-acetylglucosaminyltransferase V during hematogenous metastasis

Anoikis is a form of anchorage-dependent apoptosis, and cancer cells adopt anokis-resistance molecular machinery to conduct metastasis. Here, we report that N-acetylglucosaminyltransferase V gene expression confers anoikis resistance during cancer progression. Overexpression of N-acetylglucosaminyltransferase V protected detached cancer cells from apoptotic death, and suppression or knockout of the gene sensitized cancer cells to the apoptotic death. The gene expression also stimulated anchorage-dependent as well as anchorage-independent colony formation of cancer cells following anoikis stress treatments. Importantly, treatment with the lectin from Sambucus sieboldiana significantly sensitized anoikis-induced cancer cell deaths in vitro as well as in vivo. We propose that the lectin alone or an engineered form could offer a new therapeutic treatment option for cancer patients with advanced tumors.

14-3-3β Depletion Drives a Senescence Program in Glioblastoma Cells Through the ERK/SKP2/p27 Pathway

The induction of senescence in cancer cells has recently been implicated as a mechanism of tumor regression in response to various modes of stress. 14-3-3 proteins are conserved scaffolding molecules that are involved in various cellular functions. Among the seven isoforms, 14-3-3β is specifically expressed in astrocytoma in correlation with the malignancy grade. We investigated the possible role of 14-3-3β in the regulation of senescence induction in A172 glioblastoma cells. The knockdown of 14-3-3β by specific small interfering RNA resulted in a significant change in cellular phenotypes and an increase in cells staining positive for senescence-associated β-galactosidase. Western blotting of the 14-3-3β-depleted A172 cells revealed increased p27 expression and decreased SKP2 expression, while the expression of p53 and p21 was not altered. Subsequently, we demonstrated that ERK is a key modulator of SKP2/p27 axis activity in 14-3-3β-mediated senescence based on the following: (1) 14-3-3β knockdown decreased p-ERK levels; (2) treatment with U0126, an MEK inhibitor, completely reproduced the senescence morphology as well as the expression profiles of p27 and SKP2; and (3) the senescence phenotypes induced by 14-3-3β depletion were considerably recovered by constitutively active ERK expression. Our results indicate that 14-3-3β negatively regulates senescence in glioblastoma cells via the ERK/SKP2/p27 pathway. Furthermore, 14-3-3β depletion also resulted in senescence phenotypes in U87 glioblastoma cells, suggesting that 14-3-3β could be targeted to induce premature senescence as a therapeutic strategy against glioblastoma progression.

ERK-mediated phosphorylation of BIS regulates nuclear translocation of HSF1 under oxidative stress

B-cell lymphoma (BCL)-2-interacting cell death suppressor (BIS) has diverse cellular functions depending on its binding partners. However, little is known about the effects of biochemical modification of BIS on its various activities under oxidative stress conditions. In this study, we showed that H₂O₂ reduced BIS mobility on SDS–polyacrylamide gels in a time-dependent manner via the activation of extracellular signaling-regulated kinase (ERK). The combined results of mass spectroscopy and computational prediction identified Thr285 and Ser289 in BIS as candidate residues for phosphorylation by ERK under oxidative stress conditions. Deletion of these sites resulted in a partial reduction in the H₂O₂-induced mobility shift relative to that of the wild-type BIS protein; overexpression of the deletion mutant sensitized A172 cells to H₂O₂-induced cell death without increasing the level of intracellular reactive oxygen species. Expression of the BIS deletion mutant decreased the level of heat shock protein (HSP) 70 mRNA following H₂O₂ treatment, which was accompanied by impaired nuclear translocation of heat shock transcription factor (HSF) 1. Co-immunoprecipitation assays revealed that the binding of wild-type BIS to HSF1 was decreased by oxidative stress, while the binding of the BIS deletion mutant to HSF1 was not affected. These results indicate that ERK-dependent phosphorylation of BIS has a role in the regulation of nuclear translocation of HSF1 likely through modulation of its interaction affinity with HSF1, which affects HSP70 expression and sensitivity to oxidative stress.

Application of cancer-associated glycoforms and glycan-binding probes to an in vitro diagnostic multivariate index assay for precise diagnoses of cancer

Personalized medicine has emerged as a widely accepted trend in medicine for the efficacious and safe treatment of various diseases. It covers every medical treatment tailored according to various properties of individuals. Cancer-associated glycosylation mirrors cancer states more precisely, and this "sweet side of cancer" is thus intended to spur the development of an advanced in vitro diagnostic system. The changes of glyco-codes are often subtle and thus not easy to trace, thereby making it difficult to discriminate changes from various compounding factors. Special glycan-binding probes, often lectins, can be paired with aglycosylated antibodies to enable quantitative and qualitative measurements of glycoforms. With the in vitro diagnosis multivariate index assay (IVDMIA) considered to be capable of yielding patient-specific results, the combinatorial use of multiple glycoproteins may be a good modality to ensure disease-specific, personalized diagnoses.

Semi-quantitative measurement of a specific glycoform using a DNA-tagged antibody and lectin affinity chromatography for glyco-biomarker development

Aberrant glycosylation-targeted disease biomarker development is based on cumulative evidence that certain glycoforms are mass-produced in a disease-specific manner. However, the development process has been hampered by the absence of an efficient validation method based on a sensitive and multiplexed platform. In particular, ELISA-based analytical tools are not adequate for this purpose, mainly because of the presence of a pair of N-glycans of IgG-type antibodies. To overcome the associated hurdles in this study, antibodies were tagged with oligonucleotides with T7 promoter and then allowed to form a complex with corresponding antigens. An antibody-bound specific glycoform was isolated by lectin chromatography and quantitatively measured on a DNA microarray chip following production of fluorescent RNA by T7-trascription. This tool ensured measurement of targeted glycoforms of multiple biomarkers with high sensitivity and multiplexity. This analytical method was applied to an in vitro diagnostic multivariate index assay where a panel of hepatocellular carcinoma (HCC) biomarkers comprising alpha-fetoprotein, hemopexin, and alpha-2-macroglobulin (A2M) was examined in terms of the serum level and their fuco-fractions. The results indicated that the tests using the multiplexed fuco-biomarkers provided improved discriminatory power between non- hepatocellular carcinoma and hepatocellular carcinoma subjects compared with the alpha-fetoprotein level or fuco-alpha-fetoprotein test alone. The developed method is expected to facilitate the validation of disease-specific glycan biomarker candidates.

Hepatitis B virus X protein specially regulates the sialyl lewis a synthesis among glycosylation events for metastasis

Background

The metastasis of hematogenous cancer cells is associated with abnormal glycosylation such as sialyl lewis antigens. Although the hepatitis B virus X protein (HBx) plays important role in liver disease, the precise function of HBx on aberrant glycosylation for metastasis remains unclear.

Methods

The human hepatocellular carcinoma tissues, HBx transgenic mice and HBx-transfected cells were used to check the correlation of expressions between HBx and Sialyl lewis antigen for cancer metastasis. To investigate whether expression levels of glycosyltransferases induced in HBx-transfected cells are specifically associated with sialyl lewis A (SLA) synthesis, which enhances metastasis by interaction of liver cancer cells with endothelial cells, ShRNA and siRNAs targeting specific glycosyltransferases were used.

Results

HBx expression in liver cancer region of HCC is associated with the specific synthesis of SLA. Furthermore, the SLA was specifically induced both in liver tissues from HBx-transgenic mice and in in vitro HBx-transfected cells. HBx increased transcription levels and activities of α2-3 sialyltransferases (ST3Gal III), α1-3/4 fucosyltransferases III and VII (FUT III and VII) genes, which were specific for SLA synthesis, allowing dramatic cell-cell adhesion for metastatic potential. Interestingly, HBx specifically induced expression of N-acetylglucosamine-β1-3 galactosyltransferase V (β1-3GalT 5) gene associated with the initial synthesis of sialyl lewis A, but not β1-4GalT I. The β1-3GalT 5 shRNA suppressed SLA expression by HBx, blocking the adhesion of HBx-transfected cells to the endothelial cells. Moreover, β1-3GalT 5 silencing suppressed lung metastasis of HBx-transfected cells in in vivo lung metastasis system.

Conclusion

HBx targets the specific glycosyltransferases for the SLA synthesis and this process regulates hematogenous cancer cell adhesion to endothelial cells for cancer metastasis.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-13-222) contains supplementary material, which is available to authorized users.

PHLPP1 regulates contact inhibition by dephosphorylating Mst1 at the inhibitory site

Contact inhibition has been largely elusive despite that a loss of contact inhibition is a critical event for cancer development and progression. Here, we report that PHLPP1 is a binding protein for Mst1 and it modulates the Hippo pathway by dephosphorylating Mst1 at the inhibitory Thr(387) of Mst1. Yap1 was localized predominantly in the nucleus but marginally in the cytoplasm in HeLa cells under sparse conditions, whereas the functional protein was more directed to sequestration in the cytoplasm under dense environments. Furthermore, loss of PHLPP1 resulted in a failure of the apoptotic control. It is interesting that down-regulated expression of PHLPP1 appears to mimic the loss of contact inhibition, a hallmark of cancer.

Expression level and glycan dynamics determine the net effects of TIMP-1 on cancer progression

Tissue inhibitor of metalloproteinases (TIMPs; TIMP-1, -2, -3 and -4) are endogenous inhibitor for matrix metalloproteinases (MMPs) that are responsible for remodeling the extracellular matrix (ECM) and involved in migration, invasion and metastasis of tumor cells. Unlike under normal conditions, the imbalance between MMPs and TIMPs is associated with various diseased states. Among TIMPs, TIMP-1, a 184-residue protein, is the only N-linked glycoprotein with glycosylation sites at N30 and N78. The structural analysis of the catalytic domain of human stromelysin-1 (MMP-3) and human TIMP-1 suggests new possibilities of the role of TIMP-1 glycan moieties as a tuner for the proteolytic activities by MMPs. Because the TIMP-1 glycosylation participate in the interaction, aberrant glycosylation of TIMP-1 presumably affects the interaction, thereby leading to pathogenic dysfunction in cancer cells. TIMP-1 has not only the cell proliferation activities but also anti-oncogenic properties. Cancer cells appear to utilize these bilateral aspects of TIMP-1 for cancer progression; an elevated TIMP-1 level exerts to cancer development via MMP-independent pathway during the early phase of tumor formation, whereas it is the aberrant glycosylation of TIMP-1 that overcome the high anti-proteolytic burden. The aberrant glycosylation of TIMP-1 can thus be used as staging and/or prognostic biomarker in colon cancer. [BMB Reports 2012; 45(11): 623-628]

Decreased prevalence of high-risk human papillomavirus infection is associated with obesity

PURPOSE OF INVESTIGATION

Obesity is correlated with low education, low economic status, and lower rates of Pap smears, which are known as socio-demographic risk factors for cervical cancer. However, the association between obesity and high-risk human papillomavirus (HR-HPV) infection, the necessary cause of cervical cancer, and its related precursors, is not established.

MATERIALS AND METHODS

The authors examined the association between obesity and HR-HPV infection in 6,868 patients, who participated in annual health examinations at the Kangbuk Samsung Hospital in Seoul, Korea, from January through December 2007.

RESULTS

The prevalence of HR-HPV infection was 14.8%. Women infected with HR-HPV had a lower body mass index (BMI), when compared with non-infected women. After adjustment for alcohol intake, cigarette smoking, and marital status, HR-HPV infection was found to be negatively associated with BMI. When the analysis was stratified according to BMI, the risk of HR-HPV infection was significantly lower among those who were overweight (OR = 0.817, 95% CI = 0.680-0.982), or obese (OR = 0.688, 95% CI = 0.556-0.851), when compared with women with normal weight.

CONCLUSION

HR-HPV infection was associated with obesity defined by BMI, with a lower prevalence of infection observed in obese women.

Inhibition of MKK7-JNK by the TOR signaling pathway regulator-like protein contributes to resistance of HCC cells to TRAIL-induced apoptosis

BACKGROUND & AIMS

The TOR signaling pathway regulator-like (TIPRL) protein, the mammalian ortholog of yeast TIP41, was identified in an expression profiling screen for factors that regulate human liver carcinogenesis. We investigated the role of human TIPRL protein in hepatocellular carcinoma (HCC).

METHODS

We measured the level of TIPRL in HCC and adjacent nontumor tissues from patients. We used small interfering RNAs and zebrafish to study the function of TIPRL. We used annexin V propidium iodide staining and immunoblot analyses to measure apoptosis and activation of apoptotic signaling pathways. We used confocal microscopy, coimmunoprecipitation, and glutathione-S transferase pull-down analyses to determine interactions among mitogen-activated protein kinase kinase 7 (MKK7 or MAP2K7), TIPRL, and the protein phosphatase type 2A (PP2Ac). We studied the effects of TIPRL in tumor xenografts in mice.

RESULTS

Levels of TIPRL were higher in HCC tissues and cell lines than nontumor tissues and primary hepatocytes. Knockdown of tiprl expression in zebrafish led to large amounts of apoptosis throughout the embryos. Incubation of HCC cells, but not primary human hepatocytes, with small interfering RNA against TIPRL (siTIPRL) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) caused prolonged activation (phosphorylation) of MKK7 and c-Jun N-terminal kinase (JNK) and led to apoptosis, indicated by cleavage of procaspase-8,-3 and of poly-(adenosine diphosphate-ribose) polymerase. TIPRL bound to MKK7 and PP2Ac and promoted the interaction between MKK7 and PP2Ac. In mice, injection of HCC xenograft tumors with siTIPRL and TRAIL led to tumor apoptosis and regression.

CONCLUSIONS

TIPRL is highly up-regulated in human HCC samples and cell lines, compared with noncancerous liver tissues. TIPRL prevents prolonged activation of MKK7 and JNK and TRAIL-induced apoptosis by mediating the interaction between MKK7 and PP2Ac.

Utility of Basal luteinizing hormone levels for detecting central precocious puberty in girls

The hallmark of puberty is the progressive increase in gonadotropin-releasing hormone (GnRH) activity, reflected by an increase in the circulating concentration of luteinizing hormone (LH). The GnRH stimulation test is widely used in the evaluation of precocious puberty. The aim of our study was to assess the diagnostic utility of basal LH for the diagnosis of central precocious puberty (CPP) in girls. A total of 803 girls were referred to Ajou University Hospital for evaluation of precocious puberty between 2008 and 2011. All subjects underwent GnRH-stimulation tests as part of their evaluation. Serum LH and follicle stimulating hormone (FSH) were measured by immunoradiometric assay before and after the GnRH injection. Of the 803 subjects, 505 (62.9%) were included in the pubertal response group and 298 (37.1%) were in the prepubertal response group. Basal LH level was identified as a significant predictor for CPP. Based on the ROC curve, the optimal cut off point of basal LH related to 'pubertal response' was 1.1 IU/l, which was associated with 69.1% sensitivity and 50.5% specificity, with an area under the ROC curve of 0.620 (95% CI, 0.581-0.660). It is concluded that a single basal LH measurement can be used as a screening test to identify girls with CPP and to determine who should undergo GnRH stimulation test.

Overexpression and β-1,6-N-acetylglucosaminylation-initiated aberrant glycosylation of TIMP-1: a "double whammy" strategy in colon cancer progression

There has been ongoing debate over whether tissue inhibitor of metalloproteinase-1 (TIMP-1) is pro- or anti-oncogenic. We confirmed that TIMP-1 reinforced cell proliferation in an αvβ3 integrin-dependent manner and conferred resistance against cytotoxicity triggered by TNF-α and IL-2 in WiDr colon cancer cells. The cell-proliferative effects of TIMP-1 contributed to clonogenicity and tumor growth during the onset and early phase of tumor formation in vivo and in vitro. However, mass-produced TIMP-1 impeded further tumor growth by tightly inhibiting the activities of collagenases, which are critical for tumor growth and malignant transformation. Tumor cells could overcome this impasse by overexpression of N-acetylglucosaminyltransferase V, which deteriorates TIMP-1 into an aberrant glycoform. The aberrant glycoform of TIMP-1 was responsible for the mitigated inhibition of collagenases. The outbalanced activities of collagenases can degrade the basement membrane and the interstitial matrix, which act as a physical barrier for tumor growth and progression more efficiently. The concomitant overexpression of TIMP-1 and N-acetylglucosaminyltransferase V enabled WiDr cells to show a higher tumor growth rate as well as more malignant behaviors in a three-dimensional culture system.

Pros and cons of using aberrant glycosylation as companion biomarkers for therapeutics in cancer

Cancer treatment has been stratified by companion biomarker tests that serve to provide information on the genetic status of cancer patients and to identify patients who can be expected to respond to a given treatment. This stratification guarantees better efficiency and safety during treatment. Cancer patients, however, marginally benefit from the current companion biomarker-aided treatment regimens, presumably because companion biomarker tests are dependent solely on the mutation status of several genes status quo. In the true sense of the term, "personalized medicine", cancer patients are deemed to be identified individually by their molecular signatures, which are not necessarily confined to genetic mutations. Glycosylation is tremendously dynamic and shows alterations in cancer. Evidence is accumulating that aberrant glycosylation contributes to the development and progression of cancer, holding the promise for use of glycosylation status as a companion biomarker in cancer treatment. There are, however, several challenges derived from the lack of a reliable detection system for aberrant glycosylation, and a limited library of aberrant glycosylation. The challenges should be addressed if glycosylation status is to be used as a companion biomarker in cancer treatment and contribute to the fulfillment of personalized medicine.

Oculomotor nerve palsy caused by posterior communicating artery aneurysm: evaluation of symptoms after endovascular treatment

We report the outcome of endovascular treatment in a series of patients presenting with posterior communicating artery aneurysm causing ocular motor nerve palsy. A retrospective study was made of ten patients who were treated by coil embolization of posterior communicating artery aneurysm caused by oculomotor nerve palsy. The assessed parameters were as follows: patient's age, presence of subarachnoid hemorrhage, aneurysm size, preoperative severity of symptoms, and timing of treatment after onset of symptoms. Improvement of oculomotor nerve palsy after treatment was noted in eight patients (80.0%). Complete recovery was noted in seven patients (70.0%), partial recovery in one patient (10.0%), and no recovery in two patients (20%). Clinical presentations with early management (≤2 days) were significant in influencing recovery. Complete recovery from ocular motor nerve palsy was significantly higher in patients with initial incomplete palsy compared with initial complete palsy patients (6/6 versus 1/4). Early treatment and initial partial palsy are relevant to improving prognoses. Endovascular treatment is favored method for treating oculomotor palsy.

Generation of antibodies recognizing an aberrant glycoform of human tissue inhibitor of metalloproteinase-1 (TIMP-1) using decoy immunization and phage display

Aberrant glycosylation of human tissue inhibitor of metalloproteinase-1 (TIMP-1) by N-acetylglucosaminyltransferase-V (GnT-V) was previously reported to be related to cancer progression. Here, we report on the antibodies recognizing the structural features initiated by an addition of N-linked β(1,6)-N-acetylglucosamine (GlcNAc) branch by GnT-V on TIMP-1. Two glycoforms of TIMP-1, TIMP1-L produced in Lec4 cells without GnT-V activity and TIMP1-B in GnT-V overexpressing transfectant cells, were purified from culture supernatant and used for generation of antibodies. TIMP1-L was injected in the left hind footpad of mice as decoy and TIMP1-B in the right hind footpad as immunogen. Phage-displayed scFv library was constructed from the B cells retrieved from the right popliteal lymph nodes and subjected to panning and screening. Phage ELISA of individual clones revealed the scFv clones with preferential binding activity to TIMP1-B, and they were converted into an scFv-Fc format for further characterization of binding specificity. Glycan binding assay of an antibody, 1-9F, revealed its differential specificity toward an extension of glycan structure initiated with β(1,6)-GlcNAc linkage and terminally decorated with a sialic acid. This study demonstrates feasibility of a new strategy combining decoy immunization with phage display for the efficient generation of antibodies tracking down structural features of different glycoforms.

Galectin-3 binding protein promotes cell motility in colon cancer by stimulating the shedding of protein tyrosine phosphatase kappa by proprotein convertase 5

It has previously been reported that shedding of the PTPκ ectodomain drives enhanced motility of colon cancer cells. Herein, we provide mechanism underlying the regulation of PTPκ shedding by galectin-3 binding protein. PTPκ was inarguably scissored by the processed form of proprotein convertase 5 (subtilisin/kexin type 5), and galectin-3 binding protein which is over-produced in colon cancer cells and tissues contributed to increased cancer cell motility by acting as a negative regulator of galectin-3 at the cell surface. The high expression ratio of galectin-3 binding protein to galectin-3 was clinically correlated to lymphatic invasion. These results suggest that galectin-3 binding protein may be a potential therapeutic target for treatment of, at least, colon cancer patients with high expression of galectin-3 binding protein.

Comprehensive clinical follow-up of late effects in childhood cancer survivors shows the need for early and well-timed intervention

BACKGROUND

Due to recent advances in treatment, nearly 80% of childhood cancer patients become long-term survivors. Studies on the late effects of survivors are under way worldwide. However, data on Asian survivors remain limited.

METHODS

Data on 241 survivors at the Long-term Follow-up Clinic in Severance Hospital, South Korea, were collected and late effects were confirmed by oncologists.

RESULTS

The median follow-up from diagnosis was 7.8 years. Late effects were identified in 59.8% of survivors and 23.2% had two or more late effects. Grade 3 or higher late effects were present in 10.8%. The most common late effects involved endocrine system (29.0%). Late effects were present in 95.7% of brain tumor survivors and 36.0% of Wilms' tumor survivors. Chemotherapy, hematopoietic stem-cell transplantation and radiotherapy were significant factors associated with the number and severity of late effects (P < 0.05). Brain tumor survivors had more severe late effects (P < 0.001), whereas Wilms' tumor survivors had fewer and milder late effects (P < 0.05).

CONCLUSION

The observation that over 50% of cancer survivors suffered from late effects during the short follow-up period and that a high frequency of endocrine late effects was present indicates the need for early and well-timed intervention of the survivors.

Disialoganglioside GD3 synthase expression recruits membrane transglutaminase 2 during erythroid differentiation of the human chronic myelogenous leukemia K562 cells

By employing proteomics analysis tool, we examined the effects of GD3 synthase expression on the differentiation properties of chronic myelogenous leukemia (CML)-derived leukemia cells K562. Forced expression of GD3 synthase induced erythroid differentiation as determined by an increase in glycophorin A expression and synthesis of hemoglobins. The proteomic analysis revealed that 15 proteins were increased by GD3 synthase. In contrast, we observed three protein gel spots decreased in contents in the cell membranes of GD3 synthase-transfected K562 cells. Among the increased proteins, membrane transglutaminase 2 (TG2) was specifically increased in the cell membrane of GD3 synthase-transfected K562 cells. Then, we generated the GD3 synthase-transfected cells in the K562 cells. Interestingly, the TG2 level was increased in GD3 synthase-transfected cells compared with vector- and plasma membrane-associated ganglioside sialidase (Neu3)-transfected cells. In addition, its ability to be photoaffinity-labeled with [alpha-(32)P]GTP was also increased in the GD3 synthase- and TG2-transfected cells. Moreover, small interfering RNA (siRNA) analysis for the GD3 synthase showed the decrease or abolishment of the membrane TG2. Finally, GD3 synthase-transfected cells accelerated the erythroid differentiation. Therefore, we propose that the recruitment of TG2 into membranes by GD3 might play an important role in the erythroid differentiation in K562 cells.

Susceptibility of porcine keratocytes to immune-mediated damage in xeno-related rejection

We admixed cultured porcine keratocytes or corneal endothelial cells in the presence of human sera or peripheral blood mononuclear cells (PBMCs) for 4 to 72 hours to investigate their immune-related susceptibilities to xeno-related rejection. We evaluated complement deposition at 48 hours by flow cytometry after staining with the C3 anti-goat cy3 antibody. The inhibition of proliferation of porcine corneal cells by human sera was examined using the 3-[4,5-dimethy/thiazol-2,5-dephenyl tetrazolium bromide (MTT) assay over 24 to 72 hours. The amount of 51chromium (Cr)-release was estimated after a reaction between the porcine cells and human PBMCs for 4 hours. There was greater C3 deposition in keratocytes (60.2%) than in endothelial cells (26.9%; P = .05, Mann-Whitney U test). Both keratocytes and endothelial cells showed significant levels of proliferative inhibition over a period of 72 hours. The number of 51Cr-release cells on interleukin-2 addition was significantly higher among keratocytes (88.0%) than endothelial cells (51.4%) at a 1:100 target:effector ratio (P = .04, Mann-Whitney U test). Our present data suggested that porcine keratocytes might be key target cells in xeno-related rejections when the porcine cornea is transplanted to primates.

Novel black soy peptides with antiobesity effects: activation of leptin-like signaling and AMP-activated protein kinase

OBJECTIVE

To investigate the mechanisms underlying the antiobesity effects of a novel isoflavone-free peptide mixture (BSP) derived from black soybean.

DESIGN

Long-term effects of BSP were evaluated in diet-induced obese (DIO) mice fed a high-fat (HF) diet without or with BSP (2, 5 or 10% of energy) for 13 weeks, or for 8 weeks in combination with exercise. Acute effects of BSP on food intake and body weight in rats and leptin-deficient ob/ob mice were evaluated. Cell culture models or tissue extracts were used to investigate the mechanisms underlying the antiobesity effect.

MEASUREMENT

Total food intake, body weight gain, white adipose tissue (WAT) mass, plasma concentrations of leptin, adiponectin, cholesterol and triglyceride were measured. Janus kinase 2 (JAK2)-dependent signal transducers and activators of the transcription 3 (STAT3) phosphorylation and AMP-activated protein kinase (AMPK) activity were determined using Western-blot in cultured cells or tissue extracts.

RESULTS

DIO mice fed an HF diet with BSP (2, 5 or 10%) for 13 weeks gained less body weight (21.4, 19.8 or 17.1 g, respectively) than the mice fed an HF diet without BSP (22.6 g) concurrent with inhibition of total food intake in a dose-dependent manner. BSP also significantly decreased food intake in rats and leptin-deficient ob/ob mice. The highest dose of BSP (10%) significantly elevated the plasma adiponectin and decreased plasma triglyceride. BSP activated JAK2-dependent STAT3 in a cell model, and elevated the level of hypothalamic phospho-STAT3 in ob/ob mice. BSP also phosphorylated AMPK and acetyl-CoA carboxylase of C2C12 myocytes in a dose-dependent manner. The antiobesity effect was augmented by low-intensity wheel-based exercise. In exercised mice, BSP significantly decreased periepididymal WAT mass and body weight gain.

CONCLUSION

These results provided evidences that BSP decreased appetite and HF diet-induced body weight gain particularly in combination with exercise, through leptin-like STAT3 phosphorylation and AMPK activation.

Development of patatin knockdown potato tubers using RNA interference (RNAi) technology, for the production of human-therapeutic glycoproteins

BACKGROUND

Patatins encoded by a multi-gene family are one of the major storage glycoproteins in potato tubers. Potato tubers have recently emerged as bioreactors for the production of human therapeutic glycoproteins (vaccines). Increasing the yield of recombinant proteins, targeting the produced proteins to specific cellular compartments, and diminishing expensive protein purification steps are important research goals in plant biotechnology. In the present study, potato patatins were eliminated almost completely via RNA interference (RNAi) technology to develop potato tubers as a more efficient protein expression system. The gene silencing effect of patatins in the transgenic potato plants was examined at individual isoform levels.

RESULTS

Based upon the sequence similarity within the multi-gene family of patatins, a highly conserved target sequence (635 nts) of patatin gene pat3-k1 [GenBank accession no. DQ114421] in potato plants (Solanum tuberosum L.) was amplified for the construction of a patatin-specific hairpin RNAi (hpRNAi) vector. The CaMV 35S promoter-driven patatin hpRNAi vector was transformed into the potato cultivar Desiree by Agrobacterium-mediated transformation. Ten transgenic potato lines bearing patatin hpRNA were generated. The effects of RNA interference were characterized at both the protein and mRNA levels using 1D and 2D SDS/PAGE and quantitative real-time RT-PCR analysis. Dependent upon the patatin hpRNAi line, patatins decreased by approximately 99% at both the protein and mRNA levels. However, the phenotype (e.g. the number and size of potato tuber, average tuber weight, growth pattern, etc.) of hpRNAi lines was not distinguishable from wild-type potato plants under both in vitro and ex vitro growth conditions. During glycoprotein purification, patatin-knockdown potato tubers allowed rapid purification of other potato glycoproteins with less contamination of patatins.

CONCLUSION

Patatin-specific hpRNAi effectively suppressed the expression of a majority of patatin variants in potato tubers via the specific degradation of individual mRNAs of the patatin multi-gene family. More importantly, patatin-knockdown potato tubers appear to be an ideal host for the production of human therapeutic glycoproteins, because they eventually allow fast, easy purification of recombinant proteins, with less contamination from potato glycoprotein patatins.