The helix-loop-helix protein, Id-1, is overexpressed and regulates growth in papillary thyroid cancer

Inhibitor of Differentiation 1 (Id1) in Cancer and Cancer Therapy

The inhibitor of DNA binding (Id) proteins are regulators of cell cycle and cell differentiation. Of all Id family proteins, Id1 is mostly linked to tumorigenesis, cellular senescence as well as cell proliferation and survival. Id1 is a stem cell-like gene more than a classical oncogene. Id1 is overexpressed in numerous types of cancers and exerts its promotion effect to these tumors through different pathways. Briefly, Id1 was found significantly correlated with EMT-related proteins, K-Ras signaling, EGFR signaling, BMP signaling, PI3K/Akt signaling, WNT and SHH signaling, c-Myc signaling, STAT3 signaling, RK1/2 MAPK/Egr1 pathway and TGF-β pathway, etc. Id1 has potent effect on facilitating tumorous angiogenesis and metastasis. Moreover, high expression of Id1 plays a facilitating role in the development of drug resistance, including chemoresistance, radiation resistance and resistance to drugs targeting angiogenesis. However, controversial results were also obtained. Overall, Id1 represent a promising target of anti-tumor therapeutics based on its potent promotion effect to cancer. Numerous drugs were found exerting their anti-tumor function through Id1-related signaling pathways, such as fucoidan, berberine, tetramethylpyrazine, crizotinib, cannabidiol and vinblastine.

ID Proteins May Reduce Aggressiveness of Thyroid Tumors

ID genes have an important function in the cell cycle, and ID proteins may help identify aggressive tumors, besides being considered promising therapeutic targets. However, their role in thyroid tumors is still poorly understood. We examined ID expression and their correlation with diagnostic and prognostic features aiming to find a clinical application in differentiated thyroid carcinoma (DTC) cases. mRNA levels of ID1, ID2, ID3, and ID4 genes were quantified and their expression was observed by immunohistochemistry in 194 thyroid samples including 68 goiters, 16 follicular adenomas, 75 classic papillary thyroid carcinomas, 18 follicular variants of papillary thyroid carcinoma, 5 follicular thyroid carcinomas, and 1 anaplastic thyroid cancer, besides 11 normal thyroid tissues. DTC patients were managed according to standard protocols and followed up for M = 28 ± 16 months. ID2, ID3, and ID4 mRNA levels were higher in benign (2.0 ± 1.9; 0.6 ± 0.6; and 0.7 ± 1.0 AU, respectively) than those in malignant nodules (0.30 ± 0.62; 0.3 ± 0.3; and 0.2 ± 0.3 AU, respectively, p < 0.0001 for all three genes) and were associated with no extra thyroid invasion or metastasis at diagnosis. ID3 nuclear protein expression was higher in benign than that in malignant cells (5.2 ± 0.9 vs 3.0 ± 1.8 AU; p < 0.0001). On the contrary, the cytoplasmic expression of ID3 was higher in malignant than that in benign lesions (5.7 ± 1.5 vs 4.0 ± 1.4 AU; p < 0.0001). Our data indicate that ID genes are involved in thyroid tumorigenesis and suggest these genes act impeding the evolution of more aggressive phenotypes. The different patterns of their tissue expression may help identify malignancy and characterize thyroid lesion aggressiveness.

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.

Correlation between the expression of Id-1 and hyperthermia-associated molecules in oral squamous cell carcinoma

OBJECTIVE

To investigate the expression of inhibitor of differentiation/DNA binding (Id-1), phosphatidylinositol-3-kinase/protein kinase B pathway proteins and hyperthermia-associated protein and their association with various clinicopathological factors in oral squamous cell cancer (OSCC), and explore the relationship among them in OSCC.

METHODS

Id-1, phosphorylated protein kinase B (p-Akt), phosphorylated glycogen synthase kinase 3β (p-GSK3β) and phosphorylated heat shock factor 1 (p-HSF1) expression were assessed immunohistochemically in 76 OSCC.

RESULTS

Id-1 (73.8%), p-Akt (65.8%), p-GSK3β (60.5%) and p-HSF1 (75%) were found to be overexpressed in most of the oral cancer samples tested, and the expressions of them are correlated with advanced clinical stage, metastasis and recurrence (p<0.01), but there is no apparent relationship with gender, age, differentiation and habits (p>0.05). Survival curves show that the survival of patients with high Id-1, p-Akt, p-GSK3β and p-HSF1 expression was significantly worse than those with low Id-1, p-Akt, p-GSK3β and p-HSF1 expression (p=0.000). Id-1 expression was significantly higher in cases with high expression of p-Akt, p-GSK3β and p-HSF1 than in those with low expression (p=0.002, p=0.003, p=0.001).

CONCLUSIONS

This study revealed that there was a positive correlation between Id-1 expression and the expression of p-Akt, p-GSK3β and p-HSF1. The inhibition of Id-1 expression can improve the efficacy of hyperthermia in OSCC.

My what big eyes you have: how the Drosophila retina grows

The compound eye of the fruit fly, Drosophila melanogaster, has for decades been used extensively to study a number of critical developmental processes including tissue development, pattern formation, cell fate specification, and planar cell polarity. To a lesser degree it has been used to examine the cell cycle and tissue proliferation. Discovering the mechanisms that balance tissue growth and cell death in developing epithelia has traditionally been the realm of those using the wing disc. However, over the last decade a series of observations has demonstrated that the eye is a suitable and maybe even preferable tissue for studying tissue growth. This review will focus on how growth of the retina is controlled by the genes and pathways that govern the specification of tissue fate, the division of the epithelium into dorsal-ventral compartments, the initiation, and progression of the morphogenetic furrow and the second mitotic wave.

Id-1 overexpression in invasive ductal carcinoma cells is significantly associated with intratumoral microvessel density in ER-negative/node-positive breast cancer

The aim of this study is to investigate the possible role of inhibitor of DNA binding (Id-1) overexpression in human breast cancer. We examined Id-1 expression by immunohistochemistry in 263 human breast cancers, 15 in situ lesions and 248 invasive cancers to investigate the relationship between its expression and various clinicopathological factors. Id-1 expression was significantly higher in invasive ductal carcinoma than in in situ ductal carcinoma or other invasive cancer subtypes (P=0.029 and 0.006, respectively). We also examined the association between Id-1 expression and tumor angiogenesis by measuring microvessel densities (MVD). Regarding the endothelial cells of microvessels showed negative or very weak Id-1 expression, Id-1 overexpression was found to be significantly related to MVD (P=0.014). Furthermore, Id-1 overexpression was found to be significantly associated with higher MVD in the ER-negative and node-involved subgroups of breast cancer (P=0.040 and 0.046, respectively). These data indicate that Id-1 overexpression is significantly associated with tumor angiogenesis, especially in the ER-negative and node-positive subtypes of invasive breast cancer. Thus, Id-1 presents a possible therapeutic antitumor target molecule in ER-negative and node-positive breast cancer.

Id helix-loop-helix proteins are differentially expressed in gestational trophoblastic disease

AIMS

To assess the expression of Id proteins in trophoblastic tissues and to correlate this with clinical parameters, proliferative and apoptotic indices as well as to related oncogene expression.

METHODS AND RESULTS

Immunohistochemistry for Id1, Id2, Id3 and Id4 was performed on 83 trophoblastic tissues including 17 normal first-trimester placentas, seven term placentas, 47 hydatidiform moles (HM), and 12 spontaneous miscarriages. The four Id proteins were predominantly expressed in the villous and implantation site intermediate trophoblast. Expression of Id1 in HM was significantly higher than that in normal placenta (P = 0.0006) and spontaneous miscarriage (P = 0.0001) but did not correlate with subsequent development of gestational trophoblastic neoplasia (GTN). Id1 expression correlated with the proliferation index as assessed by MCM7 (P = 0.003) and Ki67 (P = 0.017) and with the apoptotic activity assessed by TUNEL (P = 0.001) and M30 CytoDeath antibody (P = 0.013). Moreover, the expression of Id1 correlated with the expression of p53 (P = 0.004), p21(WAF1) (/CIP1) (P = 0.003) but not with p16 (P = 0.107).

CONCLUSIONS

Id proteins may play a role in the regulation of proliferative and apoptotic activity in trophoblastic tissue and are potentially useful in differentiating molar and non-molar gestation, but are not helpful in predicting GTN.

Id1 gene expression and regulation in human thyroid tissue

The Id genes encode helix-loop-helix (HLH) transcription proteins that lack a DNA binding basic domain. Id proteins (Id1, Id2, Id3, and Id4) function as dominant negative regulators of basic HLH transcription factors by forming inactive heterodimers. Recent studies suggest that the Id proteins participate in the regulation of cell growth, differentiation, tumorigenesis and angiogenesis in a variety of cell types. This report summarizes studies done in our laboratory on the expression and regulation of the Id1 gene in human thyroid tissue, the result of activation of the major mitogen signal transduction pathways on Id1 gene expression, and the effect of the Id1 gene on thyroid cancer cell growth and differentiation.

Id genes and proteins as promising targets in cancer therapy

Since the identification of Id proteins more than a decade ago, much work has demonstrated their regulatory roles in development, cell fate and lineage determination, proliferation, differentiation, angiogenesis, invasion and migration. Recent studies reveal not only that Id protein expression is significantly correlated both with cancer progression and with overall prognosis, but also that it can be exploited as a therapeutic target. This review will focus on the recent advances in our understanding of the relationships between Id expression and cancer, as well as providing a rationale for developing therapeutic strategies using Ids as targets to treat metastatic cancers.