Activation of nuclear factor κB pathway and downstream targets survivin and livin by SHARPIN contributes to the progression and metastasis of prostate cancer

Epigenetic regulation of androgen dependent and independent prostate cancer

Prostate cancer is one of the most common malignancies among men worldwide. Besides genetic alterations, epigenetic modulations including DNA methylation, histone modifications and miRNA mediated alteration of gene expression are the key driving forces for the prostate tumor development and cancer progression. Aberrant expression and/or the activity of the epigenetic modifiers/enzymes, results in aberrant expression of genes involved in DNA repair, cell cycle regulation, cell adhesion, apoptosis, autophagy, tumor suppression and hormone response and thereby disease progression. Altered epigenome is associated with prostate cancer recurrence, progression, aggressiveness and transition from androgen-dependent to androgen-independent phenotype. These epigenetic modifications are reversible and various compounds/drugs targeting the epigenetic enzymes have been developed that are effective in cancer treatment. This chapter focuses on the epigenetic alterations in prostate cancer initiation and progression, listing different epigenetic biomarkers for diagnosis and prognosis of the disease and their potential as therapeutic targets. This chapter also summarizes different epigenetic drugs approved for prostate cancer therapy and the drugs available for clinical trials.

Cancer invasion and metastasis: Insights from murine pubertal mammary gland morphogenesis

Cancer invasion and metastasis accounts for the majority of cancer related mortality. A better understanding of the players that drive the aberrant invasion and migration of tumors cells will provide critical targets to inhibit metastasis. Postnatal pubertal mammary gland morphogenesis is characterized by highly proliferative, invasive, and migratory normal epithelial cells. Identifying the molecular regulators of pubertal gland development is a promising strategy since tumorigenesis and metastasis is postulated to be a consequence of aberrant reactivation of developmental stages. In this review, we summarize the pubertal morphogenesis regulators that are involved in cancer metastasis and revisit pubertal mammary gland transcriptome profiling to uncover both known and unknown metastasis genes. Our updated list of pubertal morphogenesis regulators shows that most are implicated in invasion and metastasis. This review highlights molecular linkages between development and metastasis and provides a guide for exploring novel metastatic drivers.

SHARPIN Enhances Ferroptosis in Synovial Sarcoma Cells via NF-κB- and PRMT5-Mediated PGC1α Reduction

Sarcoma is a rare type of cancer for which new therapeutic agents are required. Ferroptosis is a nonapoptotic cell death triggered by iron-mediated lipid peroxidation. We found that TFRC, an iron uptake protein, was expressed at higher levels in sarcoma cell lines than in noncancer and carcinoma cell lines. Glutathione peroxidase 4 (GPX4) protects cells against ferroptosis, and its inhibition using RAS-selective lethal 3 (RSL3) had an antitumor effect that was more pronounced in sarcoma cell lines, particularly synovial sarcoma cells, compared to non-sarcoma cells. Because NF-κB can provoke ferroptosis, we examined the role of SHARPIN, an activator of NF-κB, in sarcoma. We found that SHARPIN expression was significantly associated with reduced survival in cohorts of patients with cancer, including sarcoma. In addition, SHARPIN promoted the sensitivity of sarcoma cells to ferroptosis. Further analyses revealed that the PGC1α/NRF2/SLC7A11 axis and BNIP3L/NIX-mediated mitophagy are regulated through NF-κB and PRMT5 downstream of SHARPIN. Our findings suggest that ferroptosis could have a therapeutic effect in sarcoma, particularly in subpopulations with high TFRC and SHARPIN expression.

Overexpression of SHARPIN promotes tumor progression in ovarian cancer

SHARPIN (Shank-associated RH domain interacting protein) plays an important role in tumorigenesis. However, its role in ovarian cancer remains largely unknown. To investigate this issue, we systematically analyzed the amplification and expression of the SHARPIN in the TCGA database. From the database, we found that SHARPIN was amplified in ovarian cancer compared to normal ovarian tissue, and the mRNA level of SHARPIN was significantly elevated in ovarian cancer compared to non-tumorigenic ovarian tissue. In addition, we observed similar results from ovarian cancer cell lines and clinical samples from ovarian cancer patients, which indicated that increased SHARPIN expression is associated with tumorigenesis in ovarian cancer. SHARPIN knockdown inhibited the migration and invasion of ovarian cancer cells, also inhibited cell cycle and promoted apoptosis, thereby suppressing cell proliferation. RNA-seq results showed that SHARPIN significantly increased the expression of P53 and P21 and decreased the expression of Cyclin D1 and c-Myc, all of which are involved in the regulation of cell proliferation. Subsequent mechanistic exploration revealed that SHARPIN knockdown increased the expression of caspases 3 and 9, leading to apoptosis of ovarian cancer cells. We also found that high expression of SHARPIN was associated with poor prognosis of ovarian cancer patients. Collectively, we demonstrated a positive correlation between SHARPIN and ovarian cancer progression and provide a basis for combined targeted therapy strategies for future ovarian cancer treatment.

SIPL1, Regulated by MAZ, Promotes Tumor Progression and Predicts Poor Survival in Human Triple-Negative Breast Cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer owing to a lack of effective targeted therapy and acquired chemoresistance. Here, we explored the function and mechanism of shank-interacting protein-like 1 (SIPL1) in TNBC progression.

METHODS

SIPL1 expression was examined in human TNBC tissues and cell lines by quantitative reverse transcription PCR, western blot, and immunohistochemistry. SIPL1 overexpression and silenced cell lines were established in BT-549 and MDA-MB-231 cells. The biological functions of SIPL1 in TNBC were studied in vitro using the CCK-8 assay, CellTiter-Glo Luminescent Cell Viability assay, caspase-3/8/9 assay, wound healing assay, and transwell assay and in vivo using a nude mouse model. The potential mechanisms underlying the effects of SIPL1 on TNBC progression were explored using bioinformatics analysis, luciferase reporter assays, and chromatin immunoprecipitation followed by qPCR.

RESULTS

SIPL1 expression was higher in human TNBC tissues and cell lines than in adjacent normal tissues and a breast epithelial cell line (MCF10A). High expression of SIPL1 was positively correlated with poor overall and disease-free survival in patients with TNBC. SIPL1 overexpression elevated and SIPL1 silencing repressed the malignant phenotypes of TNBC cells in vitro. SIPL1 overexpression promoted xenograft tumor growth in vivo. Myc-associated zinc-finger protein (MAZ) transcriptionally activated SIPL1. Finally, we found that SIPL1 promoted TNBC malignant phenotypes via activation of the AKT/NF-κB signaling pathways.

CONCLUSIONS

These results indicate that the MAZ/SIPL1/AKT/NF-κB axis plays a crucial role in promoting the malignant phenotypes of TNBC cells.

SHARPIN regulates the development of clear cell renal cell carcinoma by promoting von Hippel-Lindau protein ubiquitination and degradation

SHANK-associated RH domain interacting protein (SHARPIN) plays an important role in carcinogenesis, as well as inflammation and immunity. Our study explored the effects and underlying mechanisms of SHARPIN in clear cell renal cell carcinoma (ccRCC). By analyzing The Cancer Genome Atlas database, we found that upregulated SHARPIN in patients with ccRCC led to a poor prognosis. Semiquantitative immunohistochemical analysis of clinical samples was carried out and the results suggested the positive association between SHARPIN and hypoxia-induced factor-2α (HIF-2α). Von Hippel-Lindau protein (pVHL) is a tumor suppressor that contributes to degrading HIF-2α. Mechanically, SHARPIN promoted the ubiquitination and proteasomal degradation of pVHL, resulting in the sustained activation of HIF-2α. The α and β domains of pVHL and ubiquitin-like domain of SHARPIN are required for the interaction. The knockdown of SHARPIN effectively inhibited acquired sorafenib resistance in ccRCC cell lines and tumor growth in xenograft models. In conclusion, our work reveals a novel posttranslational regulation of SHARPIN on pVHL, indicating that SHARPIN could be a potential target for ccRCC treatment.

Identification of Somatic Genetic Alterations Using Whole-Exome Sequencing of Uterine Leiomyosarcoma Tumors

Background

The genomic abnormalities associated with uterine leiomyosarcoma (uLMS) have not been fully elucidated to date.

Objective

To understand the pathogenesis of uLMS and to identify driver mutations and potential therapeutic targets in uLMS.

Methods

Three matched tumor-constitutional DNA pairs from patients with recurrent uLMS were subjected to whole-exome capture and next-generation sequencing. The role of the selected gene SHARPIN in uLMS was analyzed by the CCK-8 assay and colony formation assay after specific siRNA knockdown.

Results

We identified four genes with somatic SNVs, namely, SLC39A7, GPR19, ZNF717, and TP53, that could be driver mutations. We observed that 30.7% (4/13) of patients with uLMS had TP53 mutations as analyzed by direct sequencing. Analysis of somatic copy number variants (CNVs) showed regions of chromosomal gain at 1q21-23, 19p13, 17q21, and 17q25, whereas regions of chromosomal loss were observed at 2q35, 2q37, 1p36, 10q26, 6p22, 8q24, 11p15, 11q12, and 9p21. The SHARPIN gene was amplified in two patients and mutated in another (SHARPIN: NM_030974: exon2: c.G264C, p.E88D). Amplification of the SHARPIN gene was associated with shorter PFS and OS in soft tissue sarcoma, as shown by TCGA database analysis. Knockdown of SHARPIN expression was observed to decrease cell growth and colony formation in uterine sarcoma cell lines.

Conclusions

Exome sequencing revealed mutational heterogeneity of uLMS. The SHARPIN gene was amplified in uLMS and could be a candidate oncogene.

SHARPIN stabilizes β-catenin through a linear ubiquitination-independent manner to support gastric tumorigenesis

BACKGROUND

Aberrant activation of Wnt/β-catenin signaling by dysregulated post-translational protein modifications, especially ubiquitination is causally linked to cancer development and progression. Although Lys48-linked ubiquitination is known to regulate Wnt/β-catenin signaling, it remains largely obscure how other types of ubiquitination, such as linear ubiquitination governs its signaling activity.

METHODS

The expression and regulatory mechanism of linear ubiquitin chain assembly complex (LUBAC) on Wnt/β-catenin signaling was examined by immunoprecipitation, western blot and immunohistochemical staining. The ubiquitination status of β-catenin was detected by ubiquitination assay. The impacts of SHARPIN, a core component of LUBAC on malignant behaviors of gastric cancer cells were determined by various functional assays in vitro and in vivo.

RESULTS

Unlike a canonical role in promoting linear ubiquitination, SHARPIN specifically interacts with β-catenin to maintain its protein stability. Mechanistically, SHARPIN competes with the E3 ubiquitin ligase β-Trcp1 for β-catenin binding, thereby decreasing β-catenin ubiquitination levels to abolish its proteasomal degradation. Importantly, SHARPIN is required for invasiveness and malignant growth of gastric cancer cells in vitro and in vivo, a function that is largely dependent on its binding partner β-catenin. In line with these findings, elevated expression of SHARPIN in gastric cancer tissues is associated with disease malignancy and correlates with β-catenin expression levels.

CONCLUSIONS

Our findings reveal a novel molecular link connecting linear ubiquitination machinery and Wnt/β-catenin signaling via SHARPIN-mediated stabilization of β-catenin. Targeting the linear ubiquitination-independent function of SHARPIN could be exploited to inhibit the hyperactive β-catenin signaling in a subset of human gastric cancers.

SHARPIN: Role in Finding NEMO and in Amyloid-Beta Clearance and Degradation (ABCD) Pathway in Alzheimer's Disease?

SHANK- associated RH domain-interacting protein (SHARPIN) is a multifunctional protein associated with numerous physiological functions and many diseases. The primary role of the protein as a LUBAC-dependent component in regulating the activation of the transcription factor NF-κB accounts to its role in inflammation and antiapoptosis. Hence, an alteration of SHARPIN expression or genetic mutations or polymorphisms leads to the alteration of the above-mentioned primary physiological functions contributing to inflammation-associated diseases and cancer, respectively. However, there are complications of targeting SHARPIN as a therapeutic approach, which arises from the wide-range of LUBAC-independent functions and yet unknown roles of SHARPIN including neuronal functions. The identification of SHARPIN as a postsynaptic protein and the emerging studies indicating its role in several neurodegenerative diseases including Alzheimer's disease suggests a strong role of SHARPIN in neuronal functioning. This review summarizes the functional roles of SHARPIN in normal physiology and disease pathogenesis and strongly suggests a need for concentrating more studies on identifying the unknown neuronal functions of SHARPIN and hence its role in neurodegenerative diseases.

SHARPIN regulates cell proliferation of cutaneous basal cell carcinoma via inactivation of the transcriptional factors GLI2 and c‑JUN

SHANK‑associated RH domain‑interacting protein (SHARPIN) is a component of the linear ubiquitin chain assembly complex that can enhance the NF‑κB and JNK signaling pathways, acting as a tumor‑associated protein in a variety of cancer types. The present study investigated the role of SHARPIN in cutaneous basal cell carcinoma (BCC). Human BCC (n=26) and normal skin (n=5) tissues, and BCC (TE354.T) and normal skin (HaCaT) cell lines were used to evaluate SHARPIN expression level using immunohistochemistry and western blotting, respectively. A lentivirus carrying SHARPIN‑targeting or negative control short hairpin RNA was infected into TE354.T cells, and the infected stable cells were assayed to analyze tumor cell proliferation, cell cycle, apoptosis, migration and invasion by Cell Counting Kit‑8 and 5‑ethynyl‑2'‑deoxyuridine incorporation assays, flow cytometry and Transwell assays. Western blotting was performed to assess the protein expression levels of gene signaling in SHARPIN‑silenced BCC cells. SHARPIN protein expression levels were downregulated or absent in BCC cancer nests and precancerous lesions compared with normal skin samples. In addition, SHARPIN expression levels were lower in TE354.T cells compared with HaCaT cells. SHARPIN shRNA enhanced tumor cell proliferation and the S phase of the cell cycle, whereas BCC cell apoptotic rates, and migratory and invasive abilities were not significantly altered. The expression levels of cyclin D1, cyclin‑dependent kinase 4, phosphorylated‑c‑JUN and GLI family zinc finger 2 proteins were increased, whereas Patched 1 (PTCH1) and PTCH2 were decreased in the SHARPIN‑shRNA‑infected BCC cells. Therefore, the present results suggested that SHARPIN may act as a tumor suppressor during BCC development.

Subcellular Compartmentalization of Survivin is Associated with Biological Aggressiveness and Prognosis in Prostate Cancer

The role of subcellular survivin compartmentalization in the biology and prognosis of prostate cancer is unclear. We therefore investigated subcellular localization of survivin in more than 3000 prostate cancer patients by quantitative immunohistochemistry and performed transcriptomics of 250 prostate cancer patients and healthy donors using publicly available datasets. Survivin (BIRC5) gene expression was increased in primary prostate cancers and metastases, but did not differ in recurrent vs non-recurrent prostate cancers. Survivin immunohistochemistry (IHC) staining was limited exclusively to the nucleus in 900 prostate cancers (40.0%), and accompanied by various levels of cytoplasmic positivity in 1338 tumors (59.4%). 0.5% of prostate cancers did not express survivin. Nuclear and cytoplasmic survivin staining intensities were strongly associated with each other, pT category, and higher Gleason scores. Cytoplasmic but not nuclear survivin staining correlated with high tumor cell proliferation in prostate cancers. Strong cytoplasmic survivin staining, but not nuclear staining predicted an unfavorable outcome in univariate analyses. Multivariate Cox regression analysis showed that survivin is not an independent prognostic marker. In conclusion, we provide evidence that survivin expression is increased in prostate cancers, especially in metastatic disease, resulting in higher aggressiveness and tumor progression. In addition, subcellular compartmentalization is an important aspect of survivin cancer biology, as only cytoplasmic, but not nuclear survivin accumulation is linked to biological aggressiveness and prognosis of prostate cancers.

SHARPIN overexpression promotes TAK1 expression and activates JNKs and NF-κB pathway in Mycosis Fungoides

Mycosis Fungoides (MF) is the most common subtype of cutaneous T-cell lymphomas (CTCL). Shank-associated RH domain-interacting protein (SHARPIN) participates in the initiation and development of multiple tumors. However, the clinical significance of SHARPIN in MF hasn't been investigated. The c-Jun N-terminal kinases (JNKs) pathway is a member of mitogen-activated protein kinases (MAPKs). Its dysregulation is observed in various tumors including CTCL, whereas the roles of JNKs pathway in MF remain largely unknown, the relationship between SHARPIN and JNKs pathway remains elusive. Herein, we showed that upregulated expression of SHARPIN was related to poor prognosis of MF patients. In vitro experiments found increased SHARPIN expression and activation of JNKs pathway in MF cell line MyLa2059. SHARPIN induced transforming growth factor β activated kinase-1 (TAK1) transcription, which is an upstream kinase of JNKs, NF-κB and p38 pathway, leading to activation of JNKs and NF-κB pathway. SHARPIN also promoted p38 signalling independent of TAK1 expression, by which overexpression of SHARPIN induced cell proliferation, inhibited apoptosis, enhanced migration and invasion of MyLa2059. Our work provided direct evidences for effects of SHARPIN on JNKs and NF-κB pathway, and the contributing roles of JNKs, NF-κB and p38 pathway regulated by SHARPIN in the development of MF.

Sharpin suppresses β1-integrin activation by complexing with the β1 tail and kindlin-1

Background

Previously sharpin has been identified as an endogenous inhibitor of β1-integrin activation by directly binding to a conserved region in the cytoplasmic tails (CTs) of the integrin β1-associated α subunits.

Methods

Here we employed biochemical approaches and cellular analyses to evaluate the function and molecular mechanism of the sharpin-kindlin-1 complex in regulating β1-integrin activation.

Results

In this study, we found that although the inhibition of sharpin on β1-integrin activation could be confirmed, sharpin had no apparent effect on integrin αIIbβ3 activation in CHO cell system. Notably, a direct interaction between sharpin and the integrin β1 CT was detected, while the interaction of sharpin with the integrin αIIb and the β3 CTs were substantially weaker. Importantly, sharpin was able to inhibit the talin head domain binding to the integrin β1 CT, which can mechanistically contribute to inhibiting β1-integrin activation. Interestingly, we also found that sharpin interacted with kindlin-1, and the interaction between sharpin and the integrin β1 CT was significantly enhanced when kindlin-1 was present. Consistently, we observed that instead of acting as an activator, kindlin-1 actually suppressed the talin head domain mediated β1-integrin activation, indicating that kindlin-1 may facilitate recruitment of sharpin to the integrin β1 CT.

Conclusion

Taken together, our findings suggest that sharpin may complex with both kindlin-1 and the integrin β1 CT to restrict the talin head domain binding, thus inhibiting β1-integrin activation.

Downregulation of survivin by adenovirus-mediated shRNA promotes apoptosis in skin cancer cells

Background

Survivin, a member of the inhibitor of apoptosis protein family, is highly expressed in many cancers and has important roles in inhibiting apoptosis by blocking caspase activation. However, its antitumor effects remain largely unknown. Here we explore the function of survivin in skin cancer.

Methods

We used qPCR and Western blot to examine survivin expression in skin cancer patients and cell line. We generated several survivin shRNA constructs and tested the effects of survivin shRNA on cancer cell viability using MTT assay, flow cytometry, and TUNEL assay.

Results

We found that survivin was upregulated in both skin cancer patients and skin cancer cell line A431. Knockdown survivin via shRNA inhibited cancer cell proliferation and promoted apoptosis in both A431 cell and in vivo xenograft tumor mouse model. The antitumor effect is comparable to resveratrol, a drug known to inhibit cancer progression. Moreover, we showed that inhibition of survivin was able to increase the expression of cleaved caspase 7/caspase 9 and activate the ataxia-telangiectasia mutated-NF-κB pathway in A431 cells.

Conclusion

Survivin-shRNA possesses antitumor abilities in vitro and in vivo by inhibiting the proliferation and promoting apoptosis of A431 cells. It may serve as a potential anticancer target for skin cancer therapy in the future.

Aberrant expression and high-frequency mutations of SHARPIN in nonmelanoma skin cancer

Squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) have exhibited a marked increase in incidence in previous decades and are the most common malignancies in Caucasian populations. Src homology 3 and multiple ankyrin repeat domains protein-associated RH domain-interacting protein (SHARPIN) has been identified as a commonly overexpressed proto-oncogene in several types of visceral cancer. However, to the best of our knowledge, the functions of SHARPIN in nonmelanoma skin cancer (NMSC) have not been described. The present study aimed to investigate the expression of SHARPIN protein and SHARPIN mutations in NMSC. A total of 85 BCC, 77 SCC and 21 keratoacanthoma (KA) formalin-fixed paraffin-embedded (FFPE) samples were collected. SHARPIN expression was detected using immunohistochemistry. DNA was extracted from the FFPE samples, and the sequences of SHARPIN were analyzed using polymerase chain reaction. In addition, high and moderate expression levels of SHARPIN were observed in normal skin tissues and KA samples. However, the expression of SHARPIN was absent in cancer nests and was significantly low in precancerous NMSC lesions. The total mutation frequency of SHARPIN was 21.8% in BCC and 17.0% in SCC. These data indicate that SHARPIN may serve a tumor-suppressing role and be a promising diagnostic, prognostic and therapeutic biomarker in NMSC.

APE1/Ref-1 redox-specific inhibition decreases survivin protein levels and induces cell cycle arrest in prostate cancer cells

A key feature of prostate cancer progression is the induction and activation of survival proteins, including the Inhibitor of Apoptosis (IAP) family member survivin. Apurinic/apyrimidinic endonuclease 1/redox effector factor 1 (APE1/Ref-1) is a multifunctional protein that is essential in activating oncogenic transcription factors. Because APE1/Ref-1 is expressed and elevated in prostate cancer, we sought to characterize APE1/Ref-1 expression and activity in human prostate cancer cell lines and determine the effect of selective reduction-oxidation (redox) function inhibition on prostate cancer cells in vitro and in vivo. Due to the role of oncogenic transcriptional activators NFĸB and STAT3 in survivin protein expression, and APE1/Ref-1 redox activity regulating their transcriptional activity, we assessed selective inhibition of APE1/Ref-1's redox function as a novel method to halt prostate cancer cell growth and survival. Our study demonstrates that survivin and APE1/Ref-1 are significantly higher in human prostate cancer specimens compared to noncancerous controls and that APE1/Ref-1 redox-specific inhibition with small molecule inhibitor, APX3330 and a second-generation inhibitor, APX2009, decreases prostate cancer cell proliferation and induces cell cycle arrest. Inhibition of APE1/Ref-1 redox function significantly reduced NFĸB transcriptional activity, survivin mRNA and survivin protein levels. These data indicate that APE1/Ref-1 is a key regulator of survivin and a potentially viable target in prostate cancer.

The Sharpin interactome reveals a role for Sharpin in lamellipodium formation via the Arp2/3 complex

Sharpin, a multifunctional adaptor protein, regulates several signalling pathways. For example, Sharpin enhances signal-induced NF-κB signalling as part of the linear ubiquitin assembly complex (LUBAC) and inhibits integrins, the T cell receptor, caspase 1 and PTEN. However, despite recent insights into Sharpin and LUBAC function, a systematic approach to identify the signalling pathways regulated by Sharpin has not been reported. Here, we present the first 'Sharpin interactome', which identifies a large number of novel potential Sharpin interactors in addition to several known ones. These data suggest that Sharpin and LUBAC might regulate a larger number of biological processes than previously identified, such as endosomal trafficking, RNA processing, metabolism and cytoskeleton regulation. Importantly, using the Sharpin interactome, we have identified a novel role for Sharpin in lamellipodium formation. We demonstrate that Sharpin interacts with Arp2/3, a protein complex that catalyses actin filament branching. We have identified the Arp2/3-binding site in Sharpin and demonstrate using a specific Arp2/3-binding deficient mutant that the Sharpin-Arp2/3 interaction promotes lamellipodium formation in a LUBAC-independent fashion.This article has an associated First Person interview with the first author of the paper.

Transfection with Livin and Survivin shRNA inhibits the growth and proliferation of non‑small cell lung cancer cells

Lung cancer is reported to be a major public health issue worldwide and the overall prognosis of patients remains poor. The expression levels of Livin and Survivin, of the inhibitors of apoptosis (IAP) family, are associated with prognostic significance in the majority of solid tumors. Therefore, in the presents study, short hairpin (sh)RNA expression vectors inhibiting the Livin and Survivin genes were constructed to examine the effects of the transfection of Livin shRNA and/or Survivin shRNA on the biological functions of tumor cells. The transfection efficiency was measured using fluorescence reverse transcription‑quantitative polymerase chain reaction and western blot analyses. The cell growth inhibition ratio was measured using a CCK assay. Cell apoptosis following transfection and in tumor tissues were measured using a TUNEL assay, and a cancer xenograft model was used to investigate the effect of Livin shRNA and/or Survivin shRNA on tumor growth. The results indicated that the mRNA and protein expression levels were suppressed following the transfection of Livin and Survivin shRNA into tumor cells (P<0.05, compared with control group). The growth of tumor cells in vivo and in vitro was significantly inhibited following transfection with Livin and Survivin shRNA, compared with that in the other groups (P<0.05). Taken together, the transfection of cells with Livin and Survivin inhibited tumor growth in vivo and in vitro, with the co‑transfection of Livin and Survivin shRNA showing increased efficiency, compared with transfection of either the Livin vector or Survivin vector alone. The combined inhibition of Livin and Survivin may be a promising multitargeted gene therapeutic strategy in cancer treatment.

Total glucosides of paeony inhibits lipopolysaccharide-induced proliferation, migration and invasion in androgen insensitive prostate cancer cells

Previous studies demonstrated that inflammatory microenvironment promoted prostate cancer progression. This study investigated whether total glucosides of paeony (TGP), the active constituents extracted from the root of Paeonia Lactiflora Pall, suppressed lipopolysaccharide (LPS)-stimulated proliferation, migration and invasion in androgen insensitive prostate cancer cells. PC-3 cells were incubated with LPS (2.0 μg/mL) in the absence or presence of TGP (312.5 μg /mL). As expected, cells at S phase and nuclear CyclinD1, the markers of cell proliferation, were increased in LPS-stimulated PC-3 cells. Migration activity, as determined by wound-healing assay and transwell migration assay, and invasion activity, as determined by transwell invasion assay, were elevated in LPS-stimulated PC-3 cells. Interestingly, TGP suppressed LPS-stimulated PC-3 cells proliferation. Moreover, TGP inhibited LPS-stimulated migration and invasion of PC-3 cells. Additional experiment showed that TGP inhibited activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK)/p38 in LPS-stimulated PC-3 cells. Correspondingly, TGP attenuated upregulation of interleukin (IL)-6 and IL-8 in LPS-stimulated PC-3 cells. In addition, TGP inhibited nuclear translocation of signal transducer and activator of transcription 3 (STAT3) in LPS-stimulated PC-3 cells. These results suggest that TGP inhibits inflammation-associated STAT3 activation and proliferation, migration and invasion in androgen insensitive prostate cancer cells.

A novel SHARPIN-PRMT5-H3R2me1 axis is essential for lung cancer cell invasion

SHARPIN (Shank-associated RH domain interacting protein) is the main component of the linear ubiquitin chain activation complex (LUBAC). SHARPIN is involved in regulating inflammation and cancer progression. However, whether SHARPIN plays an important role in lung cancer metastasis and the potential underlying mechanism are still unknown. Here, for the first time, we reported that SHARPIN expression is closely related to lung cancer progression. Moreover, SHARPIN plays a central role in controlling lung cancer cell metastasis. Mechanistic studies further revealed that PRMT5 (Protein arginine methyltransferase 5), responsible for catalyzing arginine methylation on histones, is a novel cofactor of SHARPIN. This finding provides the basis for further study of the crosstalk between protein ubiquitination and histone methylation. We further found that SHARPIN-PRMT5 is essential for the monomethylation of histones of chromatins at key metastasis-related genes, defining a new mechanism regulating cancer invasion. A novel MLL complex (ASH2 and WDR5) was implied in the link between histone arginine2 monomethylation (H3R2me1) and histone lysine4 trimethylation (H3K4me3) for the activation of metastasis-related genes. These novel findings establish a new epigenetic paradigm in which SHARPIN-PRMT5 has distinct roles in orchestrating chromatin environments for cancer-related genes via integrating signaling between H3R2me1 and H3K4me3.

Elevation of SHARPIN Protein Levels in Prostate Adenocarcinomas Promotes Metastasis and Impairs Patient Survivals

BACKGROUND

SHARPIN, SHANK-associated RH domain interacting protein, associates with a linear ubiquitin chain assembly complex (LUBAC) to regulate inflammation and immunity. It has been reported that SHARPIN is highly expressed in several human tumors including ovarian cancer and liver cancer. We found that SHARPIN is also highly expressed in prostate cancer cell lines of DU145, LNCAP, and PC-3. Suppression of SHARPIN caused an inhibition of NF-κB signal and decreases in tumorigenesis of cultured cells in NOD/SCID mouse model. Overexpression of SHARPIN in prostate cancer cells promoted cell growth and reduced apoptosis through NF-kB/ERK/Akt pathway and apoptosis-associated proteins.

METHODS

We analyzed the expression of SHARPIN in prostate cancer tissues from 95 patients and its relationship with other clinical characteristics associated with PCA malignancies and patient survivals, and examined the impacts of SHARPIN suppression with siRNA on proliferation, angiogenesis, invasion, and expression levels of MMP-9 of prostate cancer cells and metastasis to lung by these cells in nude mice.

RESULTS

High levels of SHARPIN were associated with high malignancies of PCA and predicted shorter survivals of PCA patients. Suppression of SHARPIN impaired cell proliferation, angiogenesis, and invasion and reduced levels of MMP-9 in prostate cancer cells and reduced the size of metastatic lung tumors induced by these cells in mice.

CONCLUSIONS

SHARPIN enhances the metastasis of prostate cancer and impair patient survivals. Prostate 77:718-728, 2017. © 2017 Wiley Periodicals, Inc.

Livin enhances chemoresistance in head and neck squamous cell carcinoma

The responsiveness of head and neck squamous cell carcinoma (HNSCC) to chemotherapy widely affects prognosis. Overcoming chemoresistance is necessary to improve prognoses in patients with advanced HNSCC. Evasion of apoptosis by cancer cells is a major cause of chemoresistance. Livin, a member of the human inhibitors of apoptosis protein family, is highly expressed in various human cancer tissues and is associated with tumor progression and poor prognosis in human cancers. The aim of the present study was to evaluate the role of Livin in the susceptibility to popularly used chemotherapeutic drugs such as cisplatin, 5-fluorouracil (FU) and docetaxel in human HNSCC cell lines (SNU1041, PCI1 and PCI50 cells). Reverse transcription polymerase chain reaction and western blotting were performed to determine mRNA and protein expression levels. Cell viability and apoptosis assays were used to assess the functional effects of small-interfering RNA-mediated knockdown of Livin. Each HNSCC cell line had different sensitivity to chemotherapeutic drugs. Livin knockdown significantly enhanced cytotoxicity to cisplatin, 5-FU and docetaxel in human HNSCC cells. Livin knockdown induced apoptosis and enhanced chemotherapy-induced apoptosis to cisplatin, 5-FU and docetaxel. Consistent with this, Livin-knockdown cells showed greater expression of cleaved caspases-3 and -7 and poly(ADP-ribose)polymerase compared with that in control cells after cisplatin, 5-FU, or docetaxel treatment. In conclusion, our results suggest that siRNA-mediated Livin knockdown enhanced the chemosensitivity of the three HNSCC cell lines to cisplatin, 5-FU and docetaxel. Although further investigations are required to support these findings, our results demonstrated that novel therapeutic strategies with combined use of siRNA targeting Livin and chemotherapeutic agents may have applications in the treatment of advanced HNSCC.

Dissecting major signaling pathways in prostate cancer development and progression: Mechanisms and novel therapeutic targets

Prostate cancer (PCa) is the most frequently diagnosed non-cutaneous malignancy and leading cause of cancer mortality in men. At the initial stages, prostate cancer is dependent upon androgens for their growth and hence effectively combated by androgen deprivation therapy (ADT). However, most patients eventually recur with an androgen deprivation-resistant phenotype, referred to as castration-resistant prostate cancer (CRPC), a more aggressive form for which there is no effective therapy presently available. The current review is an attempt to cover and establish an understanding of some major signaling pathways implicated in prostate cancer development and castration-resistance, besides addressing therapeutic strategies that targets the key signaling mechanisms.

Genomic profiling of invasive melanoma cell lines by array comparative genomic hybridization

Malignant melanoma is one of the most aggressive human cancers. Invasion of cells is the first step in metastasis, resulting in cell migration through tissue compartments. We aimed to evaluate genomic alterations specifically associated with the invasive characteristics of melanoma cells. Matrigel invasion assays were used to determine the invasive properties of cell lines that originated from primary melanomas. Array comparative genomic hybridization analyses were carried out to define the chromosome copy number alterations (CNAs). Several recurrent CNAs were identified by array comparative genomic hybridization that affected melanoma-related genes. Invasive primary cell lines showed high frequencies of CNAs, including the loss of 7q and gain of 12q chromosomal regions targeting PTPN12, ADAM22, FZD1, TFPI2, GNG11, COL1A2, SMURF1, VGF, RELN and GLIPR1 genes. Gain of the GDNF (5p13.1), GPAA1, PLEC and SHARPIN (8q24.3) genes was significantly more frequent in invasive cell lines compared with the noninvasive ones. Importantly, copy number gains of these genes were also found in cell lines that originated from metastases, suggesting their role in melanoma metastasis formation. The present study describes genomic differences between invasive and noninvasive melanoma cell lines that may contribute toward the aggressive phenotype of human melanoma cells.

Sharpin promotes hepatocellular carcinoma progression via transactivation of Versican expression

Sharpin (Shank-associated RH domain-interacting protein, also known as SIPL1) is a multifunctional molecule that participates in various biological settings, including nuclear factor-κB signaling activation and tumor suppressor gene inhibition. Sharpin is upregulated in various types of cancers, including hepatocellular carcinoma (HCC), and is implicated in tumor progression. However, the exact roles of Sharpin in tumorigenesis and tumor progression remain largely unknown. Here we report novel mechanisms of HCC progression through Sharpin overexpression. In our study, Sharpin was upregulated in human HCC tissues. Increased Sharpin expression enhanced hepatoma cell invasion, whereas decrease in Sharpin expression by RNA interference inhibited invasion. Microarray analysis identified that Versican, a chondroitin sulfate proteoglycan that plays crucial roles in tumor progression and invasion, was also upregulated in Sharpin-expressing stable cells. Versican expression increased in the majority of HCC tissues and knocking down of Versican greatly attenuated hepatoma cell invasion. Sharpin expression resulted in a significant induction of Versican transcription synergistically with Wnt/β-catenin pathway activation. Furthermore, Sharpin-overexpressing cells had high tumorigenic properties in vivo. These results demonstrate that Sharpin promotes Versican expression synergistically with the Wnt/β-catenin pathway, potentially contributing to HCC development. A Sharpin/Versican axis could be an attractive therapeutic target for this currently untreatable cancer.

Identifying Cancer Driver Genes Using Replication-Incompetent Retroviral Vectors

Identifying novel genes that drive tumor metastasis and drug resistance has significant potential to improve patient outcomes. High-throughput sequencing approaches have identified cancer genes, but distinguishing driver genes from passengers remains challenging. Insertional mutagenesis screens using replication-incompetent retroviral vectors have emerged as a powerful tool to identify cancer genes. Unlike replicating retroviruses and transposons, replication-incompetent retroviral vectors lack additional mutagenesis events that can complicate the identification of driver mutations from passenger mutations. They can also be used for almost any human cancer due to the broad tropism of the vectors. Replication-incompetent retroviral vectors have the ability to dysregulate nearby cancer genes via several mechanisms including enhancer-mediated activation of gene promoters. The integrated provirus acts as a unique molecular tag for nearby candidate driver genes which can be rapidly identified using well established methods that utilize next generation sequencing and bioinformatics programs. Recently, retroviral vector screens have been used to efficiently identify candidate driver genes in prostate, breast, liver and pancreatic cancers. Validated driver genes can be potential therapeutic targets and biomarkers. In this review, we describe the emergence of retroviral insertional mutagenesis screens using replication-incompetent retroviral vectors as a novel tool to identify cancer driver genes in different cancer types.

CYLD downregulates Livin and synergistically improves gemcitabine chemosensitivity and decreases migratory/invasive potential in bladder cancer: the effect is autophagy-associated

Although GC (gemcitabine and cisplatin) chemotherapy remains an effective method for treating bladder cancer (BCa), chemoresistance is a major obstacle in chemotherapy. In this study, we determined whether gemcitabine resistance correlates with migratory/invasive potential in BCa and whether this relationship is regulated by the cylindromatosis (CYLD)-Livin module. First, we independently investigated the correlation of CYLD/Livin and gemcitabine resistance with the potential for tumor migration and invasiveness. Second, we found that co-transfected CYLD and Livin dramatically improved sensitivity to gemcitabine chemotherapy and decreased migration/invasion potential. Next, we determined that CYLD may regulate Livin by the NF-κB-dependent pathway. We also found that CYLD overexpression and Livin knockdown might improve gemcitabine chemosensitivity by decreasing autophagy and increasing apoptosis in BCa cells. Finally, the effects of CYLD-Livin on tumor growth in vivo were evaluated. Our study demonstrates that CYLD-Livin might represent a potential therapeutic for chemoresistant BCa.

Linear ubiquitination signals in adaptive immune responses

Ubiquitin can form eight different linkage types of chains using the intrinsic Met 1 residue or one of the seven intrinsic Lys residues. Each linkage type of ubiquitin chain has a distinct three-dimensional topology, functioning as a tag to attract specific signaling molecules, which are so-called ubiquitin readers, and regulates various biological functions. Ubiquitin chains linked via Met 1 in a head-to-tail manner are called linear ubiquitin chains. Linear ubiquitination plays an important role in the regulation of cellular signaling, including the best-characterized tumor necrosis factor (TNF)-induced canonical nuclear factor-κB (NF-κB) pathway. Linear ubiquitin chains are specifically generated by an E3 ligase complex called the linear ubiquitin chain assembly complex (LUBAC) and hydrolyzed by a deubiquitinase (DUB) called ovarian tumor (OTU) DUB with linear linkage specificity (OTULIN). LUBAC linearly ubiquitinates critical molecules in the TNF pathway, such as NEMO and RIPK1. The linear ubiquitin chains are then recognized by the ubiquitin readers, including NEMO, which control the TNF pathway. Accumulating evidence indicates an importance of the LUBAC complex in the regulation of apoptosis, development, and inflammation in mice. In this article, I focus on the role of linear ubiquitin chains in adaptive immune responses with an emphasis on the TNF-induced signaling pathways.

Suppression of prostate cancer progression by cancer cell stemness inhibitor napabucasin

A small population of cells with stem cell-like properties in prostate cancer (PCa), called prostate cancer stem cells (PrCSCs) or prostate stemness-high cancer cells, displays highly tumorigenic and metastatic features and may be responsible for the therapy resistance. A small molecule, napabucasin (BBI608), recently have been identified with suppression of stemness-high cancer cells in a variety of cancers. However, the effects of napabucasin on PCa cells as well as PrCSCs isolated from PCa cells have not yet been defined. The effect of napabucasin on PCa cells in cell proliferation, colony formation, and cell migration in vitro were measured by MTS, colony formation assay, and Transwell, respectively. Flow cytometry was employed to evaluate cell cycle and cell apoptosis, and the effect on tumorigenesis in vivo was examined by tumor growth assays. Furthermore, the role of napabucasin on self-renewal and survival of PrCSCs was evaluated by their ability to grow spheres and cell viability assay, respectively. Western Blot and qRT-PCR were used to determine the effect of napabucasin on the expressions of stemness markers. Decrease in cell viability, colony formation, migration, and survival with cell cycle arrest, higher sensitivity to docetaxel in vitro, and repressed tumorigenesis in vivo was observed upon napabucasin treatment. More importantly, napabucasin can obviously inhibit spherogenesis and even kill PrCSCs in vitro. Downregulation of stemness markers was observed after PrCSCs were treated with napabucasin. This study demonstrates that napabucasin may be a novel approach in the treatment of advanced PCa, specifically for castration-resistant prostate cancer (CRPC).

A novel gammaretroviral shuttle vector insertional mutagenesis screen identifies SHARPIN as a breast cancer metastasis gene and prognostic biomarker

Breast cancer (BC) is the second leading cause of malignancy among U.S. women. Metastasis results in a poor prognosis and increased mortality, but the molecular mechanisms by which metastatic tumors occur are not well understood. Identifying the genes that drive the metastatic process could provide targets for improved therapy and biomarkers to improve BC patient outcomes. Using a forward mutagenesis screen, BC cells mutagenized with a replication-incompetent gammaretroviral vector (γRV) were xenotransplanted into the mammary fat pad of immunodeficient mice. In this approach the vector provirus dysregulates nearby genes, providing a selective advantage to transduced cells to form metastases. Metastatic tumors were analyzed for proviral integration sites to identify nearby candidate metastasis genes. The γRV has a transgene cassette that allows for rescue in bacteria and rapid identification of vector integration sites. Using this approach, we identified the previously described metastasis gene WWTR1 (TAZ), and three other novel candidate metastasis genes including SHARPIN. SHARPIN was independently validated in vivo as a BC metastasis gene. Analysis of patient data showed that SHARPIN expression predicts metastasis-free survival after adjuvant therapy. Our approach has broad potential to identify genes involved in oncogenic processes for BC and other cancers. We show here it can identify both known (WWTR1) and novel (SHARPIN) BC metastasis genes.

Mutually Exclusive Roles of SHARPIN in Integrin Inactivation and NF-κB Signaling

SHANK-associated RH domain interactor (SHARPIN) inhibits integrins through interaction with the integrin α-subunit. In addition, SHARPIN enhances nuclear factor-kappaB (NF-κB) activity as a component of the linear ubiquitin chain assembly complex (LUBAC). However, it is currently unclear how regulation of these seemingly different roles is coordinated. Here, we show that SHARPIN binds integrin and LUBAC in a mutually exclusive manner. We map the integrin binding site on SHARPIN to the ubiquitin-like (UBL) domain, the same domain implicated in SHARPIN interaction with LUBAC component RNF31 (ring finger protein 31), and identify two SHARPIN residues (V267, L276) required for both integrin and RNF31 regulation. Accordingly, the integrin α-tail is capable of competing with RNF31 for SHARPIN binding in vitro. Importantly, the full SHARPIN RNF31-binding site contains residues (F263A/I272A) that are dispensable for SHARPIN-integrin interaction. Importantly, disrupting SHARPIN interaction with integrin or RNF31 abolishes SHARPIN-mediated regulation of integrin or NF-κB activity, respectively. Altogether these data suggest that the roles of SHARPIN in inhibiting integrin activity and supporting linear ubiquitination are (molecularly) distinct.

P16-specific DNA methylation by engineered zinc finger methyltransferase inactivates gene transcription and promotes cancer metastasis

Background

P16 DNA methylation is well known to be the most frequent event in cancer development. It has been reported that genetic inactivation of P16 drives cancer growth and metastasis, however, whether P16 DNA methylation is truly a driver in cancer metastasis remains unknown.

Results

A P16-specific DNA methyltransferase (P16-dnmt) expression vector is designed using a P16 promoter-specific engineered zinc finger protein fused with the catalytic domain of dnmt3a. P16-dnmt transfection significantly decreases P16 promoter activity, induces complete methylation of P16 CpG islands, and inactivates P16 transcription in the HEK293T cell line. The P16-Dnmt coding fragment is integrated into an expression controllable vector and used to induce P16-specific DNA methylation in GES-1 and BGC823 cell lines. Transwell assays show enhanced migration and invasion of these cancer cells following P16-specific DNA methylation. Such effects are not observed in the P16 mutant A549 cell line. These results are confirmed using an experimental mouse pneumonic metastasis model. Moreover, enforced overexpression of P16 in these cells reverses the migration phenotype. Increased levels of RB phosphorylation and NFκB subunit P65 expression are also seen following P16-specific methylation and might further contribute to cancer metastasis.

Conclusion

P16 methylation could directly inactivate gene transcription and drive cancer metastasis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-015-0819-6) contains supplementary material, which is available to authorized users.

Neuron-type-specific signaling by the p75NTR death receptor is regulated by differential proteolytic cleavage

Signaling by the p75 neurotrophin receptor (p75(NTR), also known as NGFR) is often referred to as cell-context dependent, but neuron-type-specific signaling by p75(NTR) has not been systematically investigated. Here, we report that p75(NTR) signals very differently in hippocampal neurons (HCNs) and cerebellar granule neurons (CGNs), and we present evidence indicating that this is partly controlled by differential proteolytic cleavage. Nerve growth factor (NGF) induced caspase-3 activity and cell death in HCNs but not in CGNs, whereas it stimulated NFκB activity in CGNs but not in HCNs. HCNs and CGNs displayed different patterns of p75(NTR) proteolytic cleavage. Whereas the p75(NTR) carboxy terminal fragment (CTF) was more abundant than the intracellular domain (ICD) in HCNs, CGNs exhibited fully processed ICD with very little CTF. Pharmacological or genetic blockade of p75(NTR) cleavage by γ-secretase abolished NGF-induced upregulation of NFκB activity and enabled induction of CGN death, phenocopying the functional profile of HCNs. Thus, the activities of multifunctional receptors, such as p75(NTR), can be tuned into narrower activity profiles by cell-type-specific differences in intracellular processes, such as proteolytic cleavage, leading to very different biological outcomes.