Overexpression of inhibitor of DNA-binding (ID)-1 protein related to angiogenesis in tumor advancement of ovarian cancers

Autophagy-mediated ID1 turnover dictates chemo-resistant fate in ovarian cancer stem cells

BACKGROUND

The mechanisms enabling dynamic shifts between drug-resistant and drug-sensitive states in cancer cells are still underexplored. This study investigated the role of targeted autophagic protein degradation in regulating ovarian cancer stem cell (CSC) fate decisions and chemo-resistance.

METHODS

Autophagy levels were compared between CSC-enriched side population (SP) and non-SP cells (NSP) in multiple ovarian cancer cell lines using immunoblotting, immunofluorescence, and transmission electron microscopy. The impact of autophagy modulation on CSC markers and differentiation was assessed by flow cytometry, immunoblotting and qRT-PCR. In silico modeling and co-immunoprecipitation identified ID1 interacting proteins. Pharmacological and genetic approaches along with Annexin-PI assay, ChIP assay, western blotting, qRT-PCR and ICP-MS were used to evaluate effects on cisplatin sensitivity, apoptosis, SLC31A1 expression, promoter binding, and intracellular platinum accumulation in ID1 depleted backdrop. Patient-derived tumor spheroids were analyzed for autophagy and SLC31A1 levels.

RESULTS

Ovarian CSCs exhibited increased basal autophagy compared to non-CSCs. Further autophagy stimulation by serum-starvation and chemical modes triggered proteolysis of the stemness regulator ID1, driving the differentiation of chemo-resistant CSCs into chemo-sensitive non-CSCs. In silico modeling predicted TCF12 as a potent ID1 interactor, which was validated by co-immunoprecipitation. ID1 depletion freed TCF12 to transactivate the cisplatin influx transporter SLC31A1, increasing intracellular cisplatin levels and cytotoxicity. Patient-derived tumor spheroids exhibited a functional association between autophagy, ID1, SLC31A1, and platinum sensitivity.

CONCLUSIONS

This study reveals a novel autophagy-ID1-TCF12-SLC31A1 axis where targeted autophagic degradation of ID1 enables rapid remodeling of CSCs to reverse chemo-resistance. Modulating this pathway could counter drug resistance in ovarian cancer.

Chlamydia Trachomatis Infection: Their potential implication in the Etiology of Cervical Cancer

Pathogenic bacterial strains can alter the normal function of cells and induce different levels of inflammatory responses that are connected to the development of different diseases, such as tuberculosis, diarrhea, cancer etc. Chlamydia trachomatis (C. trachomatis) is an intracellular obligate gram-negative bacterium which has been connected with the cervical cancer etiology. Nevertheless, establishment of causality and the underlying mechanisms of carcinogenesis of cervical cancer associated with C. trachomatis remain unclear. Studies reveal the existence of C. trachomatis in cervical cancer patients. The DNA repair pathways including mismatch repair, nucleotide excision, and base excision are vital in the abatement of accumulated mutations that can direct to the process of carcinogenesis. C. trachomatis recruits DDR proteins away from sites of DNA damage and, in this way, impedes the DDR. Therefore, by disturbing host cell-cycle control, chromatin and DDR repair, C. trachomatis makes a situation favorable for malignant transformation. Inflammation originated due to infection directs over production of reactive oxygen species (ROS) and consequent oxidative DNA damage. This review may aid our current understanding of the etiology of cervical cancer in C. trachomatis-infected patients.

Inhibitor of DNA-binding family regulates the prognosis of ovarian cancer

Aim: The mechanistic role of inhibitor of DNA binding or differentiation (ID) family in ovarian cancer (OC) has remained unclear. Materials & methods: We used the Oncomine, GEPIA, Kaplan-Meier Plotter, cBioPortal, SurvExpress, PROGgene V2, TIMER, and FunRich to evaluate the prognostic value of IDs in patients with OC. Results: the mRNA transcripts of all IDs were markedly downregulated in OC compared with normal tissue. The prognostic value of IDs was also explored within the subtypes, pathological stages, clinical stages and TP53 mutational status. The group with low-risk IDs showed relatively good overall survival (OS) compared with the high-risk group. Conclusion: ID1/3/4 may be exploited as promising prognostic biomarkers and therapeutic targets in OC patients.

Analysis of Salmonella typhimurium Protein-Targeting in the Nucleus of Host Cells and the Implications in Colon Cancer: An in-silico Approach

Background

Infections of Salmonella typhimurium (S. typhimurium) are major threats to health, threats include diarrhoea, fever, acute intestinal inflammation, and cancer. Nevertheless, little information is available about the involvement of S. typhimurium in colon cancer etiology.

Methods

The present study was designed to predict nuclear targeting of S. typhimurium proteins in the host cell through computational tools, including nuclear localization signal (NLS) mapper, Balanced Subcellular Localization predictor (BaCeILo), and Hum-mPLoc using next-generation sequencing data.

Results

Several gene expression-associated proteins of S. typhimurium have been predicted to target the host nucleus during intracellular infections. Nuclear targeting of S. typhimurium proteins can lead to competitive interactions between the host and pathogen proteins with similar cellular substrates, and it may have a possible involvement in colon cancer growth. Our results suggested that S. typhimurium releases its proteins within compartments of the host cell, where they act as a component of the host cell proteome. Protein targeting is possibly involved in colon cancer etiology during intracellular bacterial infection.

Conclusion

The results of current in-silico study showed the potential involvement of S. typhimurium infection with alteration in normal functioning of host cell which act as possible factor to connect with the growth and development of colon cancer.

Uterine double-conditional inactivation of Smad2 and Smad3 in mice causes endometrial dysregulation, infertility, and uterine cancer

SMAD2 and SMAD3 are downstream proteins in the transforming growth factor-β (TGF β) signaling pathway that translocate signals from the cell membrane to the nucleus, bind DNA, and control the expression of target genes. While SMAD2/3 have important roles in the ovary, we do not fully understand the roles of SMAD2/3 in the uterus and their implications in the reproductive system. To avoid deleterious effects of global deletion, and given previous data showing redundant function of Smad2 and Smad3, a double-conditional knockout was generated using progesterone receptor-cre (Smad2/3 cKO) mice. Smad2/3 cKO mice were infertile due to endometrial hyperproliferation observed as early as 6 weeks of postnatal life. Endometrial hyperplasia worsened with age, and all Smad2/3 cKO mice ultimately developed bulky endometrioid-type uterine cancers with 100% mortality by 8 months of age. The phenotype was hormone-dependent and could be prevented with removal of the ovaries at 6 weeks of age but not at 12 weeks. Uterine tumor epithelium was associated with decreased expression of steroid biosynthesis genes, increased expression of inflammatory response genes, and abnormal expression of cell cycle checkpoint genes. Our results indicate the crucial role of SMAD2/3 in maintaining normal endometrial function and confirm the hormone-dependent nature of SMAD2/3 in the uterus. The hyperproliferation of the endometrium affected both implantation and maintenance of pregnancy. Our findings generate a mouse model to study the roles of SMAD2/3 in the uterus and serve to provide insight into the mechanism by which the endometrium can escape the plethora of growth regulatory proteins.

Inhibitor of DNA binding proteins: implications in human cancer progression and metastasis

Inhibitor of DNA binding (ID) proteins are a class of helix-loop-helix (HLH) transcription regulatory factors that act as dominant-negative antagonists of other basic HLH proteins through the formation of non-functional heterodimers. These proteins have been shown to play critical roles in a wide range of tumor-associated processes, including cell differentiation, cell cycle progression, migration and invasion, epithelial-mesenchymal transition, angiogenesis, stemness, chemoresistance, tumorigenesis, and metastasis. The aberrant expression of ID proteins has not only been detected in many types of human cancers, but is also associated with advanced tumor stages and poor clinical outcome. In this review, we provide an overview of the key biological functions of ID proteins including affiliated signaling pathways. We also describe the regulation of ID proteins in cancer progression and metastasis, and elaborate on expression profiles in cancer and the implications for prognosis. Lastly, we outline strategies for the therapeutic targeting of ID proteins as a promising and effective approach for anticancer therapy.

[Relationship between ID1 and EGFR-TKI Resistance in Non-small Cell Lung Cancer]

背景与目的

非小细胞肺癌(non-small cell lung cancer, NSCLC)是当今世界上发病率和死亡率最高的恶性肿瘤之一，而表皮生长因子受体-酪氨酸激酶抑制剂(epidermal growth factor receptor-tyrosine kinase inhibitors, EGFR-TKI)整体有效率为30%-40%，无进展生存期(progression-free survival, PFS)为12个月。但EGFR-TKI在临床中的耐药现象也很普遍，严重影响了其抑瘤作用。因此，克服耐药、寻找一种新的与肺癌耐药相关的预后因子势在必行。本研究旨在通过体内外实验探讨DNA结合抑制因子1(differentiation inhibitory factor 1, ID1)与NSCLCEGFR-TKI耐药之间的关系，看其是否有统计学意义，并初步探讨其机制。

方法

免疫组化(immunohistochemistry, IHC)检测手术标本(肺癌组织和癌旁组织)1D1的表达；qRT-PCR、Western-blot检测并比较肺癌细胞敏感株与耐药株中ID1的表达变化；MTT检测吉非替尼对ID1慢病毒载体处理肺癌细胞的细胞增殖情况，将肺癌细胞接种至裸鼠腋下，待肿瘤生长至一定体积使用吉非替尼治疗，估算肿瘤体积。

结果

ID1在肺癌组织中的表达明显高于正常组织(P < 0.05)；ID1的表达与NSCLC EGFR-TKI耐药呈正相关(P < 0.05)。

结论

ID1在NSCLC中高表达，并且参与了NSCLC EGFR-TKI的耐药，其机制可能与STAT3磷酸化程度增加有关。

Epigenetic regulation of transcription factor promoter regions by low-dose genistein through mitogen-activated protein kinase and mitogen-and-stress activated kinase 1 nongenomic signaling

Background

The phytoestrogen, genistein at low doses nongenomically activates mitogen-activated protein kinase p44/42 (MAPK_p44/42) via estrogen receptor alpha (ERα) leading to proliferation of human uterine leiomyoma cells. In this study, we evaluated if MAPK_p44/42 could activate downstream effectors such as mitogen- and stress-activated protein kinase 1 (MSK1), which could then epigenetically modify histone H3 by phosphorylation following a low dose (1 μg/ml) of genistein.

Results

Using hormone-responsive immortalized human uterine leiomyoma (ht-UtLM) cells, we found that genistein activated MAPK_p44/42 and MSK1, and also increased phosphorylation of histone H3 at serine10 (H3S10ph) in ht-UtLM cells. Colocalization of phosphorylated MSK1 and H3S10ph was evident by confocal microscopy in ht-UtLM cells (r = 0.8533). Phosphorylation of both MSK1and H3S10ph was abrogated by PD98059 (PD), a MEK1 kinase inhibitor, thereby supporting genistein’s activation of MSK1 and Histone H3 was downstream of MAPK_p44/42. In proliferative (estrogenic) phase human uterine fibroid tissues, phosphorylated MSK1 and H3S10ph showed increased immunoexpression compared to normal myometrial tissues, similar to results observed in in vitro studies following low-dose genistein administration. Real-time RT-PCR arrays showed induction of growth-related transcription factor genes, EGR1, Elk1, ID1, and MYB (cMyb) with confirmation by western blot, downstream of MAPK in response to low-dose genistein in ht-UtLM cells. Additionally, genistein induced associations of promoter regions of the above transcription factors with H3S10ph as evidenced by Chromatin Immunoprecipitation (ChIP) assays, which were inhibited by PD. Therefore, genistein epigenetically modified histone H3 by phosphorylation of serine 10, which was regulated by MSK1 and MAPK activation.

Conclusion

Histone H3 phosphorylation possibly represents a mechanism whereby increased transcriptional activation occurs following low-dose genistein exposure.

Electronic supplementary material

The online version of this article (doi:10.1186/s12964-016-0141-2) contains supplementary material, which is available to authorized users.

Computational prediction of Mycoplasma hominis proteins targeting in nucleus of host cell and their implication in prostate cancer etiology

Cancer has long been assumed to be a genetic disease. However, recent evidence supports the enigmatic connection of bacterial infection with the growth and development of various types of cancers. The cause and mechanism of the growth and development of prostate cancer due to Mycoplasma hominis remain unclear. Prostate cancer cells are infected and colonized by enteroinvasive M. hominis, which controls several factors that can affect prostate cancer growth in susceptible persons. We investigated M. hominis proteins targeting the nucleus of host cells and their implications in prostate cancer etiology. Many vital processes are controlled in the nucleus, where the proteins targeting M. hominis may have various potential implications. A total of 29/563 M. hominis proteins were predicted to target the nucleus of host cells. These include numerous proteins with the capability to alter normal growth activities. In conclusion, our results emphasize that various proteins of M. hominis targeted the nucleus of host cells and were involved in prostate cancer etiology through different mechanisms and strategies.

Effects of upregulation of Id3 in human lung adenocarcinoma cells on proliferation, apoptosis, mobility and tumorigenicity

The inhibitor of DNA-binding/differentiation 3 (Id3) protein is a helix-loop-helix transcription factor and may have an important role in cell proliferation and differentiation. This study was to evaluate the effects of upregulation of Id3 in human lung adenocarcinoma cells on proliferation, apoptosis, mobility and tumorigenicity. Short interference RNA suppression of Id3 (miRId3) in A549 cells was used to investigate the functional role(s) of Id3. Next, we used in vitro wound-healing assay and trans-well assay to study the effects of overexpressed Id3 on migration and invasion of A549 cells. Furthermore, to explore the influence of overexpressed Id3 on in vivo tumorigenesis, adenoviruses containing Id3 gene (Ad-Id3) and empty vector (Ad-LacZ) were generated. Co-transfection of pcDNA/miRId3 and pEGFP/Id3 into A549 cells reversed the Id3-induced cell proliferation inhibition and apoptosis. Upon Id3 transfection, A549 cells displayed decreased migratory and invasive capabilities, however, co-transfection of miRId3 and Id3 into A549 cells reversed the Id3-induced inhibitions of migratory and invasive capabilities. Three groups of nude mice were inoculated with Ad-LacZ, Ad-Id3 transfectants and untransfected A549 cells, respectively. Twenty-eight days after inoculation, tumors induced by Ad-Id3 transfectants grew much more slowly compared with Ad-LacZ transfectants and control group. This study provides for the first time both in vitro and in vivo proofs that forced expression of Id3 in lung adenocarcinoma cells reduces tumor growth rate and may be a potential target for tumor suppression.

Sex steroids in uterine endometrial cancers

Some uterine endometrial cancers conserve estrogen dependency in advancement. However, the concept of advancement in tumor is complicated, because it involves simple growth in primary tumor and secondary spreading. The expression manner of estrogen receptor alpha exon 5 splicing variant, ER beta, progesterone receptor-A (N-terminus deletion mutant) is associated with metastatic potential in uterine endometrial cancers. Increased estrogen-related receptor alpha expression is related to tumor advancement with the loss of estrogen dependency. Steroid receptor coactivator-3 contributes to tumor progression and can be used as a treatment target for advanced uterine endometrial cancers. Estrogen responsive oncogenes, c-jun and c-Ha-ras, are not modi-fied by progestin in uterine endometrial cancer cells and are considered to be an instinct phenotype as such cancers. By contrast, metastatic potential of estrogen-dependent uterine endometrial cancers can be partially controlled by progestin via metastasis-related genes, E-cadherin/catenins, plasminogen activator inhibitor-1, vascular endothelial growth factor. Thus, sex steroids related phenomena are impress-ive in the advancement of uterine endometrial cancers.

Effects of suberoylanilide hydroxamic acid (SAHA) combined with paclitaxel (PTX) on paclitaxel-resistant ovarian cancer cells and insights into the underlying mechanisms

Background

Suberoylanilide hydroxamic acid (SAHA) is a member of the hydroxamic acid class of the newly developed histone deacetylase inhibitors. Recently, Suberoylanilide hydroxamic acid has attracted increasing attention because of its antitumor activity and synergistic effects in combination with a variety of traditional chemotherapeutic drugs. Paclitaxel (PTX), is a natural anticancer drugs; however, resistance to paclitaxel has become a major challenge to the efficacy of this agent. The purpose of this study was to investigate the effects of the combined application of these two drugs on the paclitaxel-resistant ovarian cancer OC3/P cell line.

Methods

In the present study, the effects of Suberoylanilide hydroxamic acid or/and paclitaxel on OC3/P cells cultured in vitro were analyzed in terms of cell viability, migration, cell-cycle progression and apoptosis by CCK-8, wound healing and flow cytometry assays. Changes in cell ultrastructure were observed by transmission electron microscopy. The expression of genes and proteins related to proliferation, apoptosis and drug resistance were analyzed by quantitative real-time polymerase chain reaction and Western blot analyses.

Results

There was no cross-resistance of the paclitaxel-resistant ovarian cancer OC3/P cells to Suberoylanilide hydroxamic acid. Suberoylanilide hydroxamic acid combined with paclitaxel significantly inhibited cell growth and reduced the migration of OC3/P cells compared with the effects of Suberoylanilide hydroxamic acid or paclitaxel alone. Q-PCR showed the combination of Suberoylanilide hydroxamic acid and paclitaxel reduced intracellular bcl-2 and c-myc gene expression and increased bax gene expression more distinctly than the application of SAHA or paclitaxel alone. Moreover, the level of mdr1 gene expression in cells treated with Suberoylanilide hydroxamic acid was lower than that of the control group (P <0.05). Western blot analysis showed that Suberoylanilide hydroxamic acid alone or in combination with paclitaxel enhanced caspase-3 protein expression and degraded ID1 protein expression in OC3/P cells.

Conclusion

Suberoylanilide hydroxamic acid inhibited the growth of paclitaxel-resistant ovarian cancer OC3/P cells and reduced migration by the induction of cell-cycle arrest, apoptosis and autophagy. These observations indicate the possible synergistic antitumor effects of sequential Suberoylanilide hydroxamic acid and paclitaxel treatment.

Increased expression of Id1 and Id3 promotes tumorigenicity by enhancing angiogenesis and suppressing apoptosis in small cell lung cancer

Constant deregulation of Id1 and Id3 has been implicated in a wide range of carcinomas. However, underlying molecular evidence for the joint role of Id1 and Id3 in the tumorigenicity of small cell lung cancer (SCLC) is sparse. Investigating the biological significance of elevated expression in SCLC cells, we found that Id1 and Id3 co-suppression resulted in significant reduction of proliferation rate, invasiveness and anchorage-independent growth. Suppressing both Id1 and Id3 expression also greatly reduced the average size of tumors produced by transfectant cells when inoculated subcutaneously into nude mice. Further investigation revealed that suppressed expression of Id1 and Id3 was accompanied by decreased angiogenesis and increased apoptosis. Therefore, the SCLC tumorigenicity suppression effect of double knockdown of Id1 and Id3 may be regulated through pathways of apoptosis and angiogenesis.

Paclitaxel-exposed ovarian cancer cells induce cancer‑specific CD4+ T cells after doxorubicin exposure through regulation of MyD88 expression

Ovarian cancer has the highest mortality rate among gynecological malignancies due to high chemoresistance to the combination of platinum with taxane. Immunotherapy against ovarian cancer is a promising strategy to develop from animal-based cancer research. We investigated changes in the immunogenicity of paclitaxel-exposed ovarian cancer cells following exposure to other chemotherapeutic drugs. Murine ovarian surface epithelial cells (MOSECs) showed some resistance to paclitaxel, a first-line therapy for ovarian cancer. However, MOSECs pre-exposed to paclitaxel died through apoptosis after incubation with doxorubicin or cisplatin for 2 h. Injected into mice, the paclitaxel-exposed MOSECs post-treated with doxorubicin induced more MOSEC-specific CD4(+) T cells and extended survival for a greater time than MOSECs treated with paclitaxel alone; and bone marrow-derived dendritic cells (BMDCs) expressed higher levels of co-stimulatory molecules and produced IL-12 after co-culture with paclitaxel-exposed MOSECs treated with doxorubicin. We also observed that in paclitaxel-exposed MOSECs treated with doxorubicin, but not cisplatin, the expression of MyD88 and related target proteins decreased compared to paclitaxel-exposed MOSECs only, while in BMDCs co-cultured with these MOSECs the expression of myeloid differentiation primary response gene 88 (MyD88) increased. These findings suggest that paclitaxel pre-exposed cancer cells treated with doxorubicin can induce significant apoptosis and a therapeutic antitumor immune response in advanced ovarian cancer.

ID2 and ID3 protein expression mirrors granulopoietic maturation and discriminates between acute leukemia subtypes

The inhibitors of DNA binding (ID) inhibit basic helix-loop-helix transcription factors and thereby guide cellular differentiation and proliferation. To elucidate the involvement of IDs in hematopoiesis and acute leukemias (AL), we analyzed ID2 and ID3 expression in hematopoiesis and leukemic blasts in bone marrow biopsies (BMB). BMB of healthy stem cell donors (n = 19) and BMB of patients with acute myeloid leukemia (AML) with myelodysplasia-related changes (AML-MD; n = 19), de novo AML (n = 20), B-acute lymphoblastic leukemia (B-ALL) (n = 23), T-ALL (n = 19), were immunohistochemically stained for ID2 and ID3 expression. The expression patterns were evaluated and quantified for each hematopoietic lineage and each leukemia subtype. In normal BMB, immature granulopoiesis showed weak ID2 and strong ID3 expression, which was lost during maturation (p < 0.001). Erythropoiesis remained negative for ID2/3 (p < 0.001). ID2/3 expression differed between immature granulopoiesis and leukemic blasts (p < 0.001). Moreover, differential ID2/3 expression was seen between AL subgroups: AML, especially AML-MD, had more ID2- (p < 0.001) and ID3-positive (p < 0.001) blasts than ALL. We show a comprehensive in situ picture of ID2/3 expression in hematopoiesis and AL. Morphologically, ID2/3 proteins seem to be involved in the granulopoietic maturation. Importantly, the distinct ID2/3 expression patterns in AL indicate a specific deregulation of ID2/3 in the various types of AL and may support subtyping of AL.

Expression of Id-1 and VEGF in non-small cell lung cancer

Angiogenesis is essential for invasive tumor growth and metastasis. Bevacizumab has been widely used for the treatment of non-small cell lung cancer (NSCLC). Various studies clearly demonstrate the relevance of Id-1 and VEGF in angiogenesis. The aim of this study was to establish the role of Id-1 expression in tumor progression and angiogenesis in relation to VEGF in NSCLC. Seventy five patients underwent surgery for lung cancers. The expressions of Id-1 and VEGF in NSCLC samples were determined by immunohistochemistry. Expression of Id-1 and VEGF showed a close correlation in NSCLC (p < 0.001). In addition, Id-1 strong expression group showed high incidence of metastasis in multivariate analysis (p = 0.028). Id-1 strong expression group had short metastasis-free survival (p = 0.008) and short recurrence-free survival (p = 0.027). Strong Id-1 expression in NSCLC had a poor prognosis in association with VEGF expression. Id-1 may function in tumor growth and progression via angiogenesis. Therefore, Id-1 is considered to be a candidate for new therapeutic target and a prognostic factor in NSCLC.

Serum regulation of Id1 expression by a BMP pathway and BMP responsive element

Immediate early genes (IEGs) are expressed upon re-entry of quiescent cells into the cell cycle following serum stimulation. These genes are involved in growth control and differentiation and hence their expression is tightly controlled. Many IEGs are regulated through Serum Response Elements (SREs) in their promoters, which bind Serum Response Factor (SRF). However, many other IEGs do not have SREs in their promoters and their serum regulation is poorly understood. We have identified SRF-independent IEGs in SRF-depleted fibroblasts. One of these, Id1, was examined more closely. We mapped a serum responsive element in the Id1 promoter and find that it is identical to a BMP responsive element (BRE). The Id1 BRE is necessary and sufficient for the serum regulation of Id1. Inhibition of the BMP pathway by siRNA depletion of Smad 4, treatment with the BMP antagonist noggin, or the BMP receptor inhibitor dorsomorphin blocked serum induction of Id1. Further, BMP2 is sufficient to induce Id1 expression. Given reports that SRC inhibitors can block Id1 expression, we tested the SRC inhibitor, AZD0530, and found that it inhibits the serum activation of Id1. Surprisingly, this inhibition is independent of SRC or its family members. Rather, we show that AZD0530 directly inhibits the BMP type I receptors. Serum induction of the Id1 related gene Id3 also required the BMP pathway. Given these and other findings we conclude that the Id family of IEGs is regulated by BMPs in serum through similar BREs. This represents a second pathway for serum regulation of IEGs.

Id1 enhances human ovarian cancer endothelial progenitor cell angiogenesis via PI3K/Akt and NF-κB/MMP-2 signaling pathways

BACKGROUND

Endothelial progenitor cells (EPCs) contribute to tumor angiogenesis and growth. We previously reported that over-expression of an inhibitor of DNA binding/differentiation 1 (Id1) in EPCs can enhance EPC proliferation, migration, and adhesion. In this study, we investigated the role of Id1 in EPC angiogenesis in patients with ovarian cancer and the underlying signaling pathway.

METHODS

Circulating EPCs from 22 patients with ovarian cancer and 15 healthy control subjects were cultured. Id1 and matrix metalloproteinase-2 (MMP-2) expression were analyzed by real-time reverse transcription-polymerase chain reaction (RT-PCR) and western blot. EPC angiogenesis was detected by tube formation assays. Double-stranded DNA containing the interference sequences was synthesized according to the structure of a pGCSIL-GFP viral vector and then inserted into a linearized vector. Positive clones were identified as lentiviral vectors that expressed human Id1 short hairpin RNA (shRNA).

RESULTS

Id1 and MMP-2 expression were increased in EPCs freshly isolated from ovarian cancer patients compared to those obtained from healthy subjects. shRNA-mediated Id1 down-regulation substantially reduced EPC angiogenesis and MMP-2 expression. Importantly, transfection of EPCs with Id1 in vitro induced phosphorylation of Akt (p-Akt) via phosphoinositide 3-kinase and increased the expression of MMP-2 via NF-κB. Blockage of both pathways by specific inhibitors (LY294002 and PDTC, respectively) abrogated Id1-enhanced EPC angiogenesis.

CONCLUSIONS

Id1 can enhance EPC angiogenesis in ovarian cancer, which is mainly mediated by the PI3K/Akt and NF-κB/MMP-2 signaling pathways. Id1 and its downstream effectors are potential targets for treatment of ovarian cancer because of their contribution to angiogenesis.

Id1 and Id3 expression is associated with increasing grade of prostate cancer: Id3 preferentially regulates CDKN1B

As transcriptional regulators of basic helix-oop-helix (bHLH) transcription and non-bHLH factors, the inhibitor of differentiation (Id1, Id2, Id3, and Id4) proteins play a critical role in coordinated regulation of cell growth, differentiation, tumorigenesis, and angiogenesis. Id1 regulates prostate cancer (PCa) cell proliferation, apoptosis, and androgen independence, but its clinical significance in PCa remains controversial. Moreover, there is lack of evidence on the expression of Id2 and Id3 in PCa progression. In this study we investigated the expression of Id2 and Id3 and reevaluated the expression of Id1 in PCa. We show that increased Id1 and Id3 protein expression is strongly associated with increasing grade of PCa. At the molecular level, we report that silencing either Id1 or Id3 attenuates cell cycle. Although structurally and mechanistically similar, our results show that both these proteins are noncompensatory at least in PCa progression. Moreover, through gene silencing approaches we show that Id1 and Id3 primarily attenuates CDKN1A (p21) and CDKN1B (p27), respectively. We also demonstrate that silencing Id3 alone significantly attenuates proliferation of PCa cells as compared with Id1. We propose that increased Id1 and Id3 expression attenuates all three cyclin-dependent kinase inhibitors (CDKN2B, -1A, and -1B) resulting in a more aggressive PCa phenotype.

Acheron regulates vascular endothelial proliferation and angiogenesis together with Id1 during wound healing

RNA binding protein acheron has proved to be either the mediator of integrin-extracellular matrix interactions or the regulatory factor that participates in vertebrate development, cell differentiation and cell death. We report the role of acheron in vascular endothelial proliferation, angiogenesis and wound healing post-trauma. Co-immunoprecipitation showed that Acheron forms a ternary complex with β1 integrin and Id1 in human umbilical vein endothelial cells following stimulation with serious trauma serum. Acheron, vascular endothelial growth factor (VEGF), and β1 integrin mRNA expression was apparently inhibited, and capillary density and wound healing rate also were reduced in Id1-deficient mice trauma model. Acheron together with Id1 significantly induces VEGF, not CD105 level inhibition by serious trauma serum for 24 h. In conclusion, we have demonstrated that acheron may be an effective mediator of promoting endothelial proliferation, angiogenesis and wound healing probably by regulating VEGF together with Id1.

Inhibitor of differentiation-1 as a novel prognostic factor in NSCLC patients with adenocarcinoma histology and its potential contribution to therapy resistance

PURPOSE

High inhibitor of differentiation-1 (Id1) levels have been found in some tumor types. We aimed to study Id1 levels and their prognostic impact in a large series of stages I to IV non-small cell lung cancer (NSCLC) patients. Experiments in cell lines and cells derived from malignant pleural effusions (MPE) were also carried out.

EXPERIMENTAL DESIGN

A total of 346 NSCLC samples (three different cohorts), including 65 matched nonmalignant tissues, were evaluated for Id1 expression by using immunohistochemistry. Additional data from a fourth cohort including 111 patients were obtained for Id1 mRNA expression analysis by using publicly available microarrays. In vitro proliferation assays were conducted to characterize the impact of Id1 on growth and treatment sensitivity.

RESULTS

Significantly higher Id1 protein levels were found in tumors compared with normal tissues (P < 0.001) and in squamous carcinomas compared with adenocarcinomas (P < 0.001). In radically treated stages I to III patients and stage IV patients treated with chemotherapy, higher Id1 levels were associated with a shorter disease-free survival and overall survival in adenocarcinoma patients in a log-rank test. A Cox model confirmed the independent prognostic value of Id1 levels for both stages I to III and stage IV patients. In silico analysis confirmed a correlation between higher Id1 mRNA levels and poor prognosis for adenocarcinoma subjects. In vitro Id1 silencing in radio/chemotherapy-resistant adenocarcinoma cells from MPEs restored sensitivity to both therapies.

CONCLUSIONS

In our series, Id1 levels showed an independent prognostic value in patients with adenocarcinoma, regardless of the stage. Id1 silencing may sensitize adenocarcinoma cells to radiotherapy and chemotherapy.

Id1: a novel therapeutic target for patients with atherosclerotic plaque rupture

Plaque neovascularization and inflammation are responsible for plaque destabilization and rupture. However, the precise triggers for inflammation and neovascularization in atherosclerosis are largely unknown. Id1 (inhibitor of DNA-binding) protein is a helix-loop-helix transcription factor and plays an important role in angiogenesis and inflammation. The expression of Id1 can be up-regulated by plaque formation factors such as vascular endothelial growth factor (VEGF), hypoxia, NAD(P)H oxidase, and TNF-alpha. Moreover, Id1 is critical to endothelial progenitor cell (EPC) population formation and angiogenesis. Evidence from diverse sources has suggested that Id1 may affect plaque destabilization through angiogenesis and inflammation. Herein we hypothesize that Id1 is an important protein for the development and progression of atherosclerotic plaque destabilization and hence blocking the expression of Id1 may serve as new targets for antiatherogenic therapy.

The PI3K/Akt pathway upregulates Id1 and integrin α4 to enhance recruitment of human ovarian cancer endothelial progenitor cells

Background

Endothelial progenitor cells (EPCs) contribute to tumor angiogenesis and growth. We aimed to determine whether inhibitors of differentiation 1 (Id1) were expressed in circulating EPCs of patients with ovarian cancer, whether Id1 could mediate EPCs mobilization and recruitment, and, if so, what underlying signaling pathway it used.

Methods

Circulating EPCs cultures were from 25 patients with ovarian cancer and 20 healthy control subjects. Id1 and integrin α4 expression were analyzed by real-time reverse transcription-polymerase chain reaction and western blot. EPCs proliferation, migration, and adhesion were detected by MTT, transwell chamber, and EPCs-matrigel adhesion assays. Double-stranded DNA containing the interference sequences were synthesized according to the structure of a pGCSIL-GFP viral vector and then inserted into a linearized vector. Positive clones were identified as lentiviral vectors that expressed human Id1 short hairpin RNA (shRNA).

Results

Id1 and integrin α4 expression were increased in EPCs freshly isolated from ovarian cancer patients compared to those obtained from healthy subjects. siRNA-mediated Id1 downregulation substantially reduced EPCs function and integrin α4 expression. Importantly, Inhibition of PI3K/Akt inhibited Id1 and integrin α4 expression, resulting in the decreasing biological function of EPCs.

Conclusions

Id1 induced EPCs mobilization and recruitment is mediated chiefly by the PI3K/Akt signaling pathway and is associated with activation of integrin α4.

The NRF2-mediated oxidative stress response pathway is associated with tumor cell resistance to arsenic trioxide across the NCI-60 panel

Background

Drinking water contaminated with inorganic arsenic is associated with increased risk for different types of cancer. Paradoxically, arsenic trioxide can also be used to induce remission in patients with acute promyelocytic leukemia (APL) with a success rate of approximately 80%. A comprehensive study examining the mechanisms and potential signaling pathways contributing to the anti-tumor properties of arsenic trioxide has not been carried out.

Methods

Here we applied a systems biology approach to identify gene biomarkers that underlie tumor cell responses to arsenic-induced cytotoxicity. The baseline gene expression levels of 14,500 well characterized human genes were associated with the GI₅₀ data of the NCI-60 tumor cell line panel from the developmental therapeutics program (DTP) database. Selected biomarkers were tested in vitro for the ability to influence tumor susceptibility to arsenic trioxide.

Results

A significant association was found between the baseline expression levels of 209 human genes and the sensitivity of the tumor cell line panel upon exposure to arsenic trioxide. These genes were overlayed onto protein-protein network maps to identify transcriptional networks that modulate tumor cell responses to arsenic trioxide. The analysis revealed a significant enrichment for the oxidative stress response pathway mediated by nuclear factor erythroid 2-related factor 2 (NRF2) with high expression in arsenic resistant tumor cell lines. The role of the NRF2 pathway in protecting cells against arsenic-induced cell killing was validated in tumor cells using shRNA-mediated knock-down.

Conclusions

In this study, we show that the expression level of genes in the NRF2 pathway serve as potential gene biomarkers of tumor cell responses to arsenic trioxide. Importantly, we demonstrate that tumor cells that are deficient for NRF2 display increased sensitivity to arsenic trioxide. The results of our study will be useful in understanding the mechanism of arsenic-induced cytotoxicity in cells, as well as the increased applicability of arsenic trioxide as a chemotherapeutic agent in cancer treatment.

Ovarian cancer creates a suppressive microenvironment to escape immune elimination

BACKGROUND

Considering the high mortality rate of ovarian cancer due to the absence of curative treatment in advanced stage or at recurrence, new therapeutic strategies are urgently needed. Immunotherapy is one of these strategies that yielded promising results in fundamental and animal research in the past years. However, implementation in clinical practice remains poor. The aim of this review is to gain insight into the mechanisms of interaction between ovarian cancer and the immune system in order to develop better immunotherapeutic strategies.

METHODS

We searched the published literature for studies focusing on interactions between ovarian cancer and the immune system, with emphasis on outcome data in order to create a knowledge base that is well grounded in clinical reality.

RESULTS

The immunological response against cancer is a critical balance between immune-activating and immune-suppressing mechanisms. Besides the immune-activating tumor infiltrating lymphocytes (TILs), immune-suppressive regulatory T-cells (Tregs), tolerance-inducing plasmacytoid dendritic cells (pDCs), B7-H4+ macrophages, immune-suppressive cytokines such as IL10 and TGF-beta are also found in the tumor environment. Myeloid-derived suppressive cells (MDSCs) are recently found to have a significant role in immune suppression in ovarian cancer in murine studies. Furthermore, vascular endothelial growth factor (VEGF) is also known to have an immune-suppressing role besides its angiogenic role. All those concerted mechanisms result in the creation of an environment where the cancer is invincible and can grow unhampered.

CONCLUSION

Further knowledge of the mechanisms involved is needed to develop better strategies and improve the clinical applicability of immunotherapy. Effective immunotherapy must combine immune-activating strategies with elimination of immune-suppressing mechanisms. We believe that tilting the balance from an immune-suppressive to an immune-active environment may have an enormous impact on the disease.