Inhibitor Of Differentiation 1 Expression Research Articles

The miR-221/222 regulates the ID1 gene expression through PTEN, c-JUN and ARF4 mediators to control cell proliferation

Objective: To explore the effect of miR-221/222 on cell proliferation and regulation of inhibitor of differentiation1 (ID1) expression concerning the value of miR-221/22 in cancer diagnosis, prognosis, or therapeutic use. Methods: Embryonic cell line (HEK293), breast cancer cell line (MCF7), and lymphoblast cell line (U937) were employed to investigate cell proliferation in the presence or absence of miR-221/222 using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay. The relation of miR-221/222 and expression of the ID1 gene was monitored via luciferase activity and real-time PCR. Quantitative PCR was used to detect the effect of miR-221/222 on the expression of cellular proteins, c-JUN, ARF4, and PTEN. Results: The miR-221/222 significantly increased the expression level of the ID1 gene in MCF7 and U937 cell lines but downregulation of the ID1 gene was revealed for transfected HEK293 cells. Level of the ID1 mRNA showed that miR-221/222 regulated the ID1 gene expression at the transcriptional level. Moreover, miR-221/222 enhanced the cellular proteins, ARF4 and c-JUN, and expression in MCF7 and U937, while inhibiting them in HEK293. These findings indicated that the effect of miR-221/222 on ARF4 and c-JUN expression in HEK293 may be mediated by different pathways from MCF7 and U937. Conclusions: Increasing levels of miR-221/222 expression are correlated with cell proliferation and the regulation of ID1 expression. ID1 regulation is a complex process and miR-221/222 may regulate its expression via c-JUN and ARF4. The value of miR-221/22 in cancer diagnosis, prognosis, or therapeutic use may be cancer type dependent.

ID1 expressing macrophages support cancer cell stemness and limit CD8+ T cell infiltration in colorectal cancer

Elimination of cancer stem cells (CSCs) and reinvigoration of antitumor immunity remain unmet challenges for cancer therapy. Tumor-associated macrophages (TAMs) constitute the prominant population of immune cells in tumor tissues, contributing to the formation of CSC niches and a suppressive immune microenvironment. Here, we report that high expression of inhibitor of differentiation 1 (ID1) in TAMs correlates with poor outcome in patients with colorectal cancer (CRC). ID1 expressing macrophages maintain cancer stemness and impede CD8+ T cell infiltration. Mechanistically, ID1 interacts with STAT1 to induce its cytoplasmic distribution and inhibits STAT1-mediated SerpinB2 and CCL4 transcription, two secretory factors responsible for cancer stemness inhibition and CD8+ T cell recruitment. Reducing ID1 expression ameliorates CRC progression and enhances tumor sensitivity to immunotherapy and chemotherapy. Collectively, our study highlights the pivotal role of ID1 in controlling the protumor phenotype of TAMs and paves the way for therapeutic targeting of ID1 in CRC.

Expression of Bone Morphogenetic Protein 14 in Liver Disease and Cancer

The activation of hepatic stellate cells (HSCs) is the key event of hepatic fibrosis. Furthermore, activated HSCs also play an important role in the progression of hepatocellular cancer (HCC). Bone morphogenetic protein 14 (BMP14) is a member of the TGF-β/BMP superfamily. So far, most studies have analyzed BMP14 in the context of bone and cartilage formation and homeostasis. The aim of this study was to assess the expression and function of BMP14 in liver fibrosis and HCC. The BMP14 expression increased during the in vitro activation of primary human HSCs and also in mouse models of liver fibrosis. In human HCC, as well as non-tumorous liver tissues, there was a significant correlation between the expression of BMP14 and alpha-smooth-muscle actin (α-SMA), an established marker for HSC activation. RNAi-mediated BMP14 suppression in activated HSCs resulted in the reduced expression of the transcription factors inhibitor of differentiation 1 (ID1) and ID2, known targets of BMP signaling. Interestingly, α-SMA and collagen expression was also reduced in BMP14-depleted cells, while treatment with recombinant BMP14 induced ID1, ID2, α-SMA and collagen expression. In human HCC cell lines, treatment with recombinant BMP14 induced proliferation, migratory activity and colony formation. In summary, our data indicate activated HSCs as a major cellular source of enhanced BMP14 expression in fibrotic liver disease and HCC, and show that BMP14 exhibits pro-fibrogenic as well as pro-tumorigenic effects. Future analyses will reveal the potential of this soluble growth factor as a therapeutic target or prognostic marker for the progression of fibrosis and HCC in patients with chronic liver disease.

TWEAK Signaling-Induced ID1 Expression Drives Malignant Transformation of Hepatic Progenitor Cells During Hepatocarcinogenesis.

The malignant transformation of hepatic progenitor cells (HPCs) in the inflammatory microenvironment is the root cause of hepatocarcinogenesis. However, the potential molecular mechanisms are still elusive. The HPCs subgroup is identified by single-cell RNA (scRNA) sequencing and the phenotype of HPCs is investigated in the primary HCC model. Bulk RNA sequencing (RNA-seq) and proteomic analyses are also performed on HPC-derived organoids. It is found that tumors are formed from HPCs in peritumor tissue at the 16th week in a HCC model. Furthermore, it is confirmed that the macrophage-derived TWEAK/Fn14 promoted the expression of inhibitor of differentiation-1 (ID1) in HPCs via NF-κB signaling and a high level of ID1 induced aberrant differentiation of HPCs. Mechanistically, ID1 suppressed differentiation and promoted proliferation in HPCs through the inhibition of HNF4α and Rap1GAP transcriptions. Finally, scRNA sequencing of HCC patients and investigation of clinical specimens also verified that the expression of ID1 is correlated with aberrant differentiation of HPCs into cancer stem cells, patients with high levels of ID1 in HPCs showed a poorer prognosis. This study provides important intervention targets and a theoretical basis for the clinical diagnosis and treatment of HCC.

Interplay between transforming growth factor-\u03b2 and Nur77 in dual regulations of inhibitor of differentiation 1 for colonic tumorigenesis

The paradoxical roles of transforming growth factor-β (TGFβ) signaling and nuclear receptor Nur77 in colon cancer development are known but the underlying mechanisms remain obscure. Inhibitor of differentiation 1 (ID1) is a target gene of TGFβ and a key promoter for colon cancer progression. Here, we show that Nur77 enhances TGFβ/Smad3-induced ID1 mRNA expression through hindering Smurf2-mediated Smad3 mono-ubiquitylation, resulting in ID1 upregulation. In the absence of TGFβ, however, Nur77 destabilizes ID1 protein by promoting Smurf2-mediated ID1 poly-ubiquitylation, resulting in ID1 downregulation. Interestingly, TGFβ stabilizes ID1 protein by switching Nur77 interaction partners to inhibit ID1 ubiquitylation. This also endows TGFβ with an active pro-tumorigenic action in Smad4-deficient colon cancers. Thus, TGFβ converts Nur77’s role from destabilizing ID1 protein and cancer inhibition to inducing ID1 mRNA expression and cancer promotion, which is highly relevant to colon cancer stemness, metastasis and oxaliplatin resistance. Our data therefore define the integrated duality of Nur77 and TGFβ signaling in regulating ID1 expression and provide mechanistic insights into the paradoxical roles of TGFβ and Nur77 in colon cancer progression.

Cigarette smoking promotes keratinocyte malignancy via generation of cancer stem-like cells.

Objectives: Cigarette smoking is involved in the pathogenesis of head and neck squamous cell carcinoma (HNSCC). However, the underlying molecular mechanisms of cigarette smoking-induced HNSCC carcinogenesis are unclear and may involve cancer stem-like cell generation. We examined the effects of cigarette smoke condensate (CSC) on the formation of cancer stem-like cells, which are rich in octamer-binding transcription factor (OCT)-4, inhibitor of differentiation 1 (ID1), nuclear factor (NF)-κB, and B lymphoma Mo-MLV insertion region 1 homolog (BMI-1).Materials and Methods: We used in vitro, in vivo, and archival human HNSCC tissue analysis to evaluate the effects of CSC on cancer stem-like cell formation.Results: We found that CSC regulated OCT-4 expression, which subsequently regulated ID1 and NF-κB, at the promoter, mRNA, and protein levels in vitro. Furthermore, OCT-4 knockdown with siRNA reduced ID1 expression. ID1 and NF-κB synergistically increased the expression of BMI-1 and stimulated keratinocyte sphere generation. In vivo, ID1 and NF-κB acted together to generate malignant xenograft tumors, which were aggressive locally and systemically metastatic. Clinical data confirmed that ID1- and NF-κB-positive patients had poor clinical outcomes and 5-year disease-free survival.Conclusion: Our data suggest that smoking cigarettes promoted cancer stem-like cell generation in the head and neck area via the OCT-4/ID1/NF-κB/BMI-1 signaling pathway.

Inhibitor of Differentiation 1 (ID1) Facilitates the Efficacy of Sorafenib in Non-Small Cell Lung Cancer Cells through Suppressing Epithelial to Mesenchymal Transition.

BackgroundSorafenib, which is a multitargeted kinase inhibitor, has shown some antitumor effects in patients with non-small cell lung cancer (NSCLC). However, the potential target of sorafenib’s antitumor activity is largely unknown. Moreover, definitive predictive biomarkers of benefit have rarely been reported.Material/MethodsThe alteration in inhibitor of differentiation 1 (ID1) expression in NSCLC cells with sorafenib treatment was detected by western blotting. The sensitivity of NSCLC cells to sorafenib was observed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium) assay. Loss-of-function and gain-of-function experiments were performed to observe the role of ID1 expression in epithelial to mesenchymal transition (EMT) progression.ResultsInitially, we observed that ID1 was downregulated in NSCLC cells treated with sorafenib. The response of NSCLC cells to sorafenib was inhibited by the transfection of small interfering RNAs (siRNAs) targeting ID1. In contrast, the transfection of ID1-overexpressing plasmids improved the response of NSCLC cells to sorafenib. Further experiments indicated that ID1 is expressed at high levels in epithelial H460 cells and expressed at low levels in mesenchymal H358 cells. Loss-of-function and gain-of-function experiments suggested that ID1 negatively regulates EMT in NSCLC.ConclusionsThe expression of ID1 is dose-dependently inhibited by sorafenib, and the overexpression of ID1 contributes to the antitumor activity of sorafenib by suppressing EMT development. Our results indicate that ID1 might be a potential target for the antitumor activity of sorafenib in NSCLC and that targeting ID1 is a feasible strategy to improve the sensitivity of NSCLC cells to sorafenib.

High expression of ID1 in monocytes is strongly associated with phenotypic and functional MDSC markers in advanced melanoma

The efficacy of immunotherapies for malignant melanoma is severely hampered by local and systemic immunosuppression mediated by myeloid-derived suppressor cells (MDSC). Inhibitor of differentiation 1 (ID1) is a transcriptional regulator that was shown to be centrally involved in the induction of immunosuppressive properties in myeloid cells in mice, while it was overexpressed in CD11b+ cells in the blood of late-stage melanoma patients. Therefore, we comprehensively assessed ID1 expression in PBMC from stage III and IV melanoma patients, and studied ID1 regulation in models for human monocyte differentiation towards monocyte-derived dendritic cells. A highly significant elevation of ID1 was observed in CD33+CD11b+CD14+HLA-DRlow monocytic MDSC in the blood of melanoma patients compared to their HLA-DRhigh counterparts, while expression of ID1 correlated positively with established MDSC markers S100A8/9 and iNOS. Moreover, expression of ID1 in monocytes significantly decreased in PBMC samples taken after surgical removal of melanoma metastases, compared to those taken before surgery. Finally, maturation of monocyte-derived DC coincided with a significant downregulation of ID1. Together, these data indicate that increased ID1 expression is strongly associated with expression of phenotypic and immunosuppressive markers of monocytic MDSC, while downregulation is associated with a more immunogenic myeloid phenotype. As such, ID1 may be an additional phenotypic marker for monocytic MDSC. Investigation of ID1 as a pharmacodynamic biomarker or its use as a target for modulating MDSC is warranted.

Expansion and maintenance of primary corneal epithelial stem/progenitor cells by inhibition of TGFβ receptor I-mediated signaling

Transforming growth factor β (TGFβ) signaling is one of the most important signaling pathways regulating cell behavior in ocular tissues. Its functions are mainly linked to tissue fibrosis and inflammatory responses in ophthalmology. In epithelial cells, however, the growth inhibitory activity of TGFβ was reported in both non-ocular and ocular tissues. Since TGFβ is a bifunctional regulator that either inhibits or stimulates cell proliferation according to the specific context, we examined the effect of inhibition of TGFβ receptor (TβR) I-mediated signaling on primary corneal epithelial cells (CECs) in serum- and feeder-free conditions. The mouse CECs were isolated from the eyeballs of 6–8 weeks old female C57BL/6 mice using dispase and trypsin separately, cultivated in defined Keratinocyte serum-free medium (KSFM) with supplements (the complete medium) without feeder layer. Cells were divided into three groups, those cultured in complete medium additionally supplemented with 10 μM SB-431542, a specific inhibitor of TβR-I, were SB-CECs; those cultured in complete medium additionally supplemented with 10 ng/ml SRI-011381, a TGF-beta signaling agonist, were SRI-CECs; those cultured in complete medium without SB-431542 or SRI-011381 were control CECs. The growth rate and morphology were analyzed by light microscopy. The identity and stemness of cells was investigated through marker staining of p63, inhibitor of differentiation 1 (ID1), cytokeratin 12 (K12), cytokeratin 14 (K14), PAX6, pSmad3, alpha smooth muscle Actin (αSMA) and E-cadherin (E-cad); Real-time quantitative (RT-PCR) analysis of p63; Western blot analysis of ID1; as well as colony forming assay, sphere forming assay, healing wound in vitro assay and air-lifting interface assay. The results showed SB-CECs subcultured steadily, achieved sustained expansion, and expanded almost thrice faster than control CECs. Expanded SB-CECs exhibited smaller and more compact morphology, up-regulated p63 and ID1, as well as better performed colony-forming capacity, sphere-forming capacity, in vitro wound healing capacity, and the capacity to stratify and differentiate on air-lifting interface. Preliminary tests on human limbal epithelial cells (HLECs) showed the same results as mouse CECs. Interestingly, the ID1 expression pattern was almost identical to p63, the typical marker for corneal epithelial stem/progenitor cell (CESC/CEPC), in cultured CECs and normal corneal sections. Since ID1 has been proven to be regulated negatively by TGFβ signaling in epithelial cells and plays a role in blocking cell differentiation, its derepression by TβR-I inhibitor could be, at least in part, the underlying cause of CESC/CEPC expansion and the synchronously up-regulated expression of p63 in SB-CECs. In conclusion, inhibition of TβR-I-mediated signaling, CESCs/CEPCs achieved efficient long-term expansion in a feeder- and serum-free condition in vitro. And derepression of ID1 could be the underlying cause. Meanwhile, ID1 could serve as a marker for CESC/CEPC. These results may advance the basic and clinical CESC/CEPC research.

ZEB1-AS1 is associated with poor prognosis in non-small-cell lung cancer and influences cell migration and apoptosis by repressing ID1.

Long non-coding RNAs (lncRNAs) have been reported to play a vital role in non-small-cell lung cancer (NSCLC). ZEB1-AS1 overexpression predicts a poor prognosis in osteosarcoma and colorectal cancers. In the current study, we determined the clinical significance and prognostic value of ZEB1-AS1 in patients with NSCLC. The expression of ZEB1-AS1 and inhibitor of differentiation-1 (ID1) was measured using qRT-PCR and Western blot. Cell growth, migration, and invasion were determined using colony formation assays, Transwell assay, and flow cytometry, respectively. Tumor growth was determined with a xenograft model. ZEB1-AS1 was significantly up-regulated in NSCLC tissues compared with normal samples. ZEB1-AS1 overexpression was significantly associated with advanced tumor, lymph node, and metastases (TNM) stage and tumor size, as well as poorer overall survival. Moreover, ZEB1-AS1 knockdown inhibited NSCLC cell proliferation and migration, and promoted cell apoptosis. In addition, a chromatin immunoprecipitation assay revealed that ZEB1-AS1 interacted with STAT3, thereby repressing ID1 expression. Furthermore, rescue experiments indicated that ZEB1-AS1 functioned as an oncogene partly by repressing ID1 in NSCLC cells. Taken together, our findings indicate that ZEB1-AS1 serves as a promising therapeutic target to predict the prognosis of NSCLC.

Knockdown of inhibitor of differentiation 1 suppresses proliferation and induces apoptosis by inactivating PI3K/Akt/mTOR signaling in hemangioma-derived endothelial cells

Hemangioma (HA) is one of the commonest benign vascular neoplasms of infancy. Inhibitor of differentiation 1 (ID-1) has been reported to be an oncogene in multiple cancers. However, the role of ID-1 and its molecular mechanism in HA progression have not been elucidated. In the present study, we found that ID-1 expression at mRNA and protein levels was up-regulated in HA-derived endothelial cells (HDECs). Knockdown of ID-1 inhibited proliferation, facilitated apoptosis, and enhanced propranolol cytotoxicity in HDECs. Knockdown of ID-1 decreased the protein levels of phospholyrated protein kinase-B (Akt) and phospholyrated mammalian target of rapamycin (mTOR). Inhibition of PI3K/Akt/mTOR pathway by LY294002 abrogated ID-1-mediated pro-proliferation and anti-apoptosis effects in HDECs. In conclusion, knockdown of ID-1 suppressed proliferation and promoted apoptosis by inactivating phosphatidylinositol 3-kinase (PI3K)/Akt/mTOR signaling in HDECs, shedding light on the function of ID-1 in HA progression and highlighting the therapeutic value of ID-1 for HA.

The roles of ID-1 in human pancreatic ductal adenocarcinoma and the therapeutic effects of 2-methoxyestradiol.

Pancreatic ductal adenocarcinoma (PDAC) has poor prognosis and high mortality rate. Inhibitor of differentiation-1 (ID-1) overexpression has already been reported to be associated with low survival, but the detailed roles of ID-1 in PDAC are unclear. As an ID-1 inhibitor, 2-methoxyestradiol (2-ME) has been shown effective in the antitumor therapies, but its effect on PDAC is unknown. In this study, ID-1 overexpression and knockdown stable SW1990 cells were used to examine proliferation, migration and invasion abilities. Effectiveness of 2-ME was estimated in vivo, as well as in vitro by survival analysis, magnetic resonance imaging and tissue analysis. PDAC patients were retrospectively reviewed to assess the ID-1 expression and prognosis. We found that ID-1 was closely associated with in vitro SW1990 cells proliferation, migration and invasion abilities, as well as the expression of HIF-1α, VEGF and MMP-9. 2-ME was shown to be effective on tumor suppression both in vivo and in vitro, perhaps mainly by ID-1 regulation. Moreover, the relevance between high ID-1 expression and poor prognosis was validated in PDAC patients. Our data collectively reveals the roles of ID-1 in PDAC malignancy, and suggests 2-ME treatment may be a potential alternative chemotherapeutic agent for PDAC patients.

ID1 promotes hepatocellular carcinoma proliferation and confers chemoresistance to oxaliplatin by activating pentose phosphate pathway

BackgroundDrug resistance is one of the major concerns in the treatment of hepatocellular carcinoma (HCC). The aim of the present study was to determine whether aberrant high expression of the inhibitor of differentiation 1(ID1) confers oxaliplatin-resistance to HCC by activating the pentose phosphate pathway (PPP).MethodsAberrant high expression of ID1 was detected in two oxaliplatin-resistant cell lines MHCC97H–OXA(97H–OXA) and Hep3B–OXA(3B–OXA). The lentiviral shRNA or control shRNA was introduced into the two oxaliplatin-resistant cell lines. The effects of ID1 on cell proliferation, apoptosis and chemoresistance were evaluated in vitro and vivo. The molecular signaling mechanism underlying the induction of HCC proliferation and oxaliplatin resistance by ID1 was explored. The prognostic value of ID1/G6PD signaling in HCC patients was assessed using the Cancer Genome Atlas (TCGA) database.ResultsID1 was upregulated in oxaliplaitin-resistant HCC cells and promoted HCC cell proliferation and oxaliplatin resistance. Silencing ID1 expression in oxaliplaitin-resistant HCC cell lines inhibited cell proliferation and sensitized oxaliplaitin-resistant cells to death. ID1 knockdown significantly decreased the expression of glucose-6-phosphate dehydrogenase (G6PD), a key enzyme of the PPP. Silencing ID1 expression blocked the activation of G6PD, decreased the production of PPP NADPH, and augmented reactive oxygen and species (ROS), thus inducing cell apoptosis. Study of the molecular mechanism showed that ID1 induced G6PD promoter transcription and activated PPP through Wnt/β-catenin/c-MYC signaling. In addition, ID1/G6PD signaling predicted unfavorable prognosis of HCC patients on the basis of TCGA.ConclusionsOur study provided the first evidence that ID1 conferred oxaliplatin resistance in HCC by activating the PPP. This newly defined pathway may have important implications in the research and development of new more effective anti-cancer drugs.

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。

Inhibitor of differentiation 1 is a candidate prognostic marker in multicentric Castleman’s disease

Castleman's disease (CD) is a benign lymphoproliferative disorder characterized by dysfunctional lymphatic node hyperplasia. Lymphatic node hyperplasia is associated with elevated levels of inhibitor of differentiation 1 (ID1) in many human tumors. To assess the possible role of ID1 expression as a prognostic marker in multicentric CD (MCD), intra-lymph node ID1 expression was analyzed and related to clinical characteristics and outcomes in 48 patients. Furthermore, the correlation between ID1 and possible signaling molecules such as interleukin-6 (IL6), phosphorylated extracellular response kinase (p-ERK), and vascular endothelial growth factor C (VEGFC) was explored on six fresh MCD surgical specimens. Immunohistochemistry revealed that the patients with extensive ID1 expression had significantly poorer prognosis, compared to those with localized ID1. In addition, ID1 was positively associated with levels of IL6, p-ERK, and VEGFC. We conclude that ID1 may ultimately be a prognostic marker in MCD and that the IL6/ERK/VEGFC pathway is involved in the progress of this disease.

MicroRNA-381 Represses ID1 and is Deregulated in Lung Adenocarcinoma

MicroRNAs are small, noncoding RNAs that suppress gene expression by binding to the 3' untranslated region (UTR) and thereby repress translation or decrease messenger RNA stability. Inhibitor of differentiation 1 (ID1) is a putative stem-cell gene involved in invasion and angiogenesis. We previously showed that ID1 is regulated by Src kinases, overexpressed in human lung adenocarcinoma, and targeted by Src-dependent microRNAs. The current study focused on the association between miR-381 and ID1 in lung adenocarcinoma. An ID1 3'UTR-luciferase reporter assay was used to determine whether miR-381 directly targets ID1. Human lung cancer cell lines were stably transduced with a precursor of miR-381 to evaluate its role on ID1 expression and to investigate changes in cell migration and invasion. The Src tyrosine kinase inhibitors saracatinib and dasatinib were used to repress ID1 expression. MiR-381 expression was measured in 18 human lung adenocarcinomas and corresponding normal lung tissue by quantitative reverse-transcription polymerase chain reaction. ID1 is a direct target of miR-381 as shown by 3'UTR luciferase reporter assays. MiR-381 expression was negatively correlated with ID1 expression in lung cancer cell lines. Ectopic expression of miR-381 reduced ID1 mRNA and protein levels, and significantly decreased cell migration and invasion. Furthermore, miR-381 was significantly downregulated in human lung adenocarcinomas, and low miR-381 expression levels correlated with poor prognosis. These results suggest that downregulation of miR-381 and thus induction of its target ID1 may contribute to the metastatic potential of lung adenocarcinomas. Further studies to explore potential therapeutic strategies, including Src inhibitors, are ongoing.

Identification of ID‐1 as a potential target gene of MMSET in multiple myeloma

The frequently detected t(4;14)(p16.3;q32) translocation in multiple myeloma (MM) results in a dysregulation of two potential oncogenes: multiple myeloma SET domain (MMSET) and fibroblast growth factor receptor 3 (FGFR3). As the expression of FGFR3 is undetectable in 30% of the t(4;14)+ MM patients, MMSET has been suggested to play an important role in the malignant transformation associated with the t(4;14) translocation. Screening with a real-time polymerase chain reaction (PCR) found complex expression patterns of the MMSET transcripts in fluorescence-activated cell sorted (FACS)-purified plasma cells (PCs) from 15 t(4;14)+ MM patients. In addition, potential target genes of MMSET type I and II were identified, using microarray analyses of MMSET transfected cell lines. Subsequently, the expression of potential target genes was verified by real-time PCR in FACS-purified PCs from 15 t(4;14)+ and 22 t(4;14)- MM patients. We suggest that the inhibitor of differentiation 1 (ID-1) is a target gene of MMSET, based on its upregulation in MMSET transfected cell lines and a significant association between the t(4;14) translocation and ID-1 expression in MM patients (P = 0.002). As high levels of ID-1 are associated with cancer, our findings indicate that MMSET promotes oncogenic transformation in t(4;14)+ MM patients by transcriptional activation of ID-1 expression.