Inhibitor of DNA binding 1 (Id1) mediates stemness of colorectal cancer cells through the Id1-c-Myc-PLAC8 axis via the Wnt/β-catenin and Shh signaling pathways

Detailed survey of an in vitro intestinal epithelium model by single-cell transcriptomics

The co-culture of two adult human colorectal cancer cell lines, Caco-2 and HT29, on Transwell is commonly used as an in vitro gut mimic, yet the translatability of insights from such a system to adult human physiological contexts is not fully characterized. Here, we used single-cell RNA sequencing on the co-culture to obtain a detailed survey of cell type heterogeneity in the system and conducted a holistic comparison with human physiology. We identified the intestinal stem cell-, transit amplifying-, enterocyte-, goblet cell-, and enteroendocrine-like cells in the system. In general, the co-culture was fetal intestine-like, with less variety of gene expression compared to the adult human gut. Transporters for major types of nutrients were found in the majority of the enterocytes-like cells in the system. TLR 4 was not expressed in the sample, indicating that the co-culture model is incapable of mimicking the innate immune aspect of the human epithelium.

Transcription factor 3 promotes migration and invasion potential and maintains cancer stemness by activating ID1 expression in esophageal squamous cell carcinoma

Transcription factor 3 (TCF3) is a member of the basic Helix - Loop - Helix (bHLH) transcription factor (TF) family and is encoded by the TCF3 gene (also known as E2A). It has been shown that TCF3 functions as a key transcription factor in the pathogenesis of several human cancers and plays an important role in stem cell maintenance and carcinogenesis. However, the effect of TCF3 in the progression of esophageal squamous cell carcinoma (ESCC) is poorly known. In our study, TCF3 was found to express highly and correlated with cancer stage and prognosis. TCF3 was shown to promote ESCC invasion, migration, and drug resistance both from the results of in vivo and in vitro assays. Moreover, further studies suggested that TCF3 played these roles through transcriptionally regulating Inhibitor of DNA binding 1(ID1). Notably, we also found that TCF3 or ID1 was associated with ESCC stemness. Furthermore, TCF3 was correlated with the expression of cancer stemness markers CD44 and CD133. Therefore, maintaining cancer stemness might be the underlying mechanism that TCF3 transcriptionally regulated ID1 and further promoted ESCC progression and drug resistance.

Orai3 Calcium Channel Contributes to Oral/Oropharyngeal Cancer Stemness through the Elevation of ID1 Expression

Emerging evidence indicates that intracellular calcium (Ca2+) levels and their regulatory proteins play essential roles in normal stem cell proliferation and differentiation. Cancer stem-like cells (CSCs) are subpopulations of cancer cells that retain characteristics similar to stem cells and play an essential role in cancer progression. Recent studies have reported that the Orai3 calcium channel plays an oncogenic role in human cancer. However, its role in CSCs remains underexplored. In this study, we explored the effects of Orai3 in the progression and stemness of oral/oropharyngeal squamous cell carcinoma (OSCC). During the course of OSCC progression, the expression of Orai3 exhibited a stepwise augmentation. Notably, Orai3 was highly enriched in CSC populations of OSCC. Ectopic Orai3 expression in non-tumorigenic immortalized oral epithelial cells increased the intracellular Ca2+ levels, acquiring malignant growth and CSC properties. Conversely, silencing of the endogenous Orai3 in OSCC cells suppressed the CSC phenotype, indicating a pivotal role of Orai3 in CSC regulation. Moreover, Orai3 markedly increased the expression of inhibitor of DNA binding 1 (ID1), a stemness transcription factor. Orai3 and ID1 exhibited elevated expression within CSCs compared to their non-CSC counterparts, implying the functional importance of the Orai3/ID1 axis in CSC regulation. Furthermore, suppression of ID1 abrogated the CSC phenotype in the cell with ectopic Orai3 overexpression and OSCC. Our study reveals that Orai3 is a novel functional CSC regulator in OSCC and further suggests that Orai3 plays an oncogenic role in OSCC by promoting cancer stemness via ID1 upregulation.

Prognostic implications of the ID1 expression in acute myeloid leukemia patients treated in a resource-constrained setting

INTRODUCTION

The aberrant expression of the inhibitor of DNA binding (ID1) gene has been frequently associated with the leukemogenesis and prognostication acute myeloid leukemia (AML), although its clinical importance has never been investigated in patients treated outside well-controlled clinical trials.

METHODS

Using quantitative real-time polymerase chain reaction, we investigated the role of the ID1 expression in the clinical outcomes of non-selected patients with acute myeloid leukemia treated in a real-life setting.

RESULTS

Overall, 128 patients were enrolled. Patients with high ID1 expression had a lower 3-year overall survival (OS) rate of 9%, with the 95% confidence interval (95%CI) at 3 to 20%, compared to patients with a low ID1 expression (22%, 95%CI: 11 - 34%) (p = 0.037), although these findings did not retain significance after adjustment (hazard ratio (HR): 1.5, 95%CI: 0.98 - 2.28; p = 0.057). The ID1 expression had no impact on post-induction outcomes (disease-free survival, p = 0.648; cumulative incidence of relapse, p = 0.584).

CONCLUSIONS

Although we are aware thar our data are confronted with many variables that cannot be fully controlled, including drug unavailability, risk-adapted treatment, comorbidities and the time from diagnosis to treatment initiation, we are firm believers that such an initiative can provide more realistic data on understudied populations, in particular those from low- and middle-income countries.

STAT3-Mediated Promoter-Enhancer Interaction Up-Regulates Inhibitor of DNA Binding 1 (ID1) to Promote Colon Cancer Progression

BACKGROUND

High expression of inhibitor of DNA binding 1 (ID1) correlates with poor prognosis in colorectal cancer (CRC). Aberrant enhancer activation in regulating ID1 transcription is limited.

METHODS

Immunohistochemistry (IHC), quantitative RT-PCR (RT-qPCR) and Western blotting (WB) were used to determine the expression of ID1. CRISPR-Cas9 was used to generate ID1 or enhancer E1 knockout cell lines. Dual-luciferase reporter assay, chromosome conformation capture assay and ChIP-qPCR were used to determine the active enhancers of ID1. Cell Counting Kit 8, colony-forming, transwell assays and tumorigenicity in nude mice were used to investigate the biological functions of ID1 and enhancer E1.

RESULTS

Human CRC tissues and cell lines expressed a higher level of ID1 than normal controls. ID1 promoted CRC cell proliferation and colony formation. Enhancer E1 actively regulated ID1 promoter activity. Signal transducer and activator of transcription 3 (STAT3) bound to ID1 promoter and enhancer E1 to regulate their activity. The inhibitor of STAT3 Stattic attenuated ID1 promoter and enhancer E1 activity and the expression of ID1. Enhancer E1 knockout down-regulated ID1 expression level and cell proliferation in vitro and in vivo.

CONCLUSIONS

Enhancer E1 is positively regulated by STAT3 and contributes to the regulation of ID1 to promote CRC cell progression and might be a potential target for anti-CRC drug studies.

Anti-Cancer Activity of Cannabis sativa Phytocannabinoids: Molecular Mechanisms and Potential in the Fight against Ovarian Cancer and Stem Cells

Ovarian cancer (OC) is the most lethal gynecological malignancy, with about 70% of cases diagnosed only at an advanced stage. Cannabis sativa, which produces more than 150 phytocannabinoids, is used worldwide to alleviate numerous symptoms associated with various medical conditions. Recently, studies across a range of cancer types have demonstrated that the phytocannabinoids Δ9-trans-tetrahydrocannabinol (THC) and cannabidiol (CBD) have anti-cancer activity in vitro and in vivo, but also the potential to increase other drugs’ adverse effects. THC and CBD act via several different biological and signaling pathways, including receptor-dependent and receptor-independent pathways. However, very few studies have examined the effectiveness of cannabis compounds against OC. Moreover, little is known about the effectiveness of cannabis compounds against cancer stem cells (CSCs) in general and OC stem cells (OCSCs) in particular. CSCs have been implicated in tumor initiation, progression, and invasion, as well as tumor recurrence, metastasis, and drug resistance. Several hallmarks and concepts describe CSCs. OCSCs, too, are characterized by several markers and specific drug-resistance mechanisms. While there is no peer-reviewed information regarding the effect of cannabis and cannabis compounds on OCSC viability or development, cannabis compounds have been shown to affect genetic pathways and biological processes related to CSCs and OCSCs. Based on evidence from other cancer-type studies, the use of phytocannabinoid-based treatments to disrupt CSC homeostasis is suggested as a potential intervention to prevent chemotherapy resistance. The potential benefits of the combination of chemotherapy with phytocannabinoid treatment should be examined in ovarian cancer patients.

Significant position of C-myc in colorectal cancer: a promising therapeutic target

Colorectal cancer (CRC) is a malignant tumor initiating from the mucosa of the colorectum. According to the 2020 statistics from the World Health Organization, there are 10.0% CRC cases among all 19.3 million new cancers, followed by lung and breast cancer, and 9.4% CRC cases among all 9.9 million cancer deaths, ranking second. The population of CRC patients in China is large, and its incidence and mortality continue to increase each year. Despite the continuous development of surgical methods, chemotherapy, radiotherapy, targeted therapy and immunotherapy, the overall survival of CRC patients remains low. Past research has suggested that c-myc plays a pivotal role in the development of CRC. A higher expression level of c-Myc is a negative prognostic marker in CRC. However, there are few drugs targeting c-myc directly. Therefore, we focused on discovering the mechanism of c-myc in CRC to provide a reference for a better therapy choice for patients.

PLAC8 Overexpression Promotes Lung Cancer Cell Growth via Wnt/β-Catenin Signaling

The PLAC8 expression in lung cancer tissues and in vitro grown lung cancer cells, as well as the involvement of the Wnt/β-Catenin signaling pathway, was investigated in this process. PLAC8 protein expression in human lung cancer tissues and lung tumor cells of different strains was discovered using immunohistochemistry staining and Western blot, respectively. Animal models of PLAC8 overexpression and knockdown were created using lentivirus. The development in tumor tissue was seen both in vitro and vivo. The Wnt/β-Catenin signaling pathway played an important part in this process, as shown by the dual luciferase reporter gene system. PLAC8 expression was elevated in lung cancer tissues and plasma and decreased in plasma after lung tumor resection. PLAC8 upregulation promotes cell proliferation in vivo and in vitro, while PLAC8 downregulation inhibits cell viability and proliferation. The results of the dual luciferase reporter gene system suggest that PLAC8 can significantly activate the Wnt/β-Catenin signaling pathway in cells and can conduct signaling through it. A potential treatment targeting the prognosis of lung cancer patients may be PLAC8 overexpression, which promotes the lung cancer cell proliferation through controlling the Wnt/β-Catenin signaling pathway.

Inhibitor of DNA binding 2 knockdown inhibits the growth and liver metastasis of colorectal cancer

BACKGROUND

Liver metastasis of colorectal cancer (CRC) remains high mortality and the mechanism is still unknown. Here we investigated the effects of inhibitor of DNA binding 2 (Id2) on growth and liver metastasis of CRC.

METHODS

qPCR and western blotting were used to demonstrate mRNA and protein expressions in Id2-knockdown HCT116 cells. Cell growth was observed by cell proliferation assay, colony formation assay and flow cytometry. Cell migration and invasion were observed with wound healing assay and transwell migration and invasion assay. The effects of Id2 knockdown on tumor growth and liver metastasis in vivo were evaluated respectively with subcutaneous tumor model and colorectal liver metastasis model by injecting HCT116 cells into the mesentery triangle of cecum in mice.

RESULTS

Id2 overexpression was found in CRC cell lines. Id2 knockdown resulted in a reduction in the proliferation, colony formation, migration and invasion of HCT116 cells. The suppression of cell proliferation was accompanied by the cell cycle arrest in the G0/G1 phase with down-regulation of Cyclin D1, Cyclin E, p-Cdk2/3, Cdk6, p-p27 and up-regulation of p21 and p27. Id2 knockdown reversed epithelial-mesenchymal transition (EMT) through increasing E-Cadherin and inhibiting N-Cadherin, Vimentin, β-catenin, Snail and Slug. Id2 was also found to inhibit CRC metastasis via MMP2, MMP9 and TIMP-1. Furthermore, Id2 knockdown suppressed CRC liver metastasis in vivo.

CONCLUSION

Id2 promotes CRC growth through activation of the PI3K/AKT signaling pathway, and triggers EMT to enhance CRC migration and invasion.

The Role and Research Progress of Inhibitor of Differentiation 1 in Atherosclerosis

Inhibitor of differentiation 1 has a helix-loop-helix (HLH) structure, belongs to a class of molecules known as the HLH trans-acting factor family, and plays an important role in advancing the cell cycle, promoting cell proliferation and inhibiting cell differentiation. Recent studies have confirmed that inhibitor of differentiation 1 plays an important role in the endothelial-mesenchymal transition of vascular endothelial cells, angiogenesis, reendothelialization after injury, and the formation and rupture of atherosclerotic plaques. An in-depth understanding of the role of inhibitor of differentiation 1 in atherosclerosis will provide new ideas and strategies for the treatment of related diseases.

Therapeutic strategies targeting Wnt/β‑catenin signaling for colorectal cancer (Review)

Colorectal cancer (CRC) is one of the most common carcinomas. Although great progress has been made in recent years, CRC survival remains unsatisfactory due to high metastasis and recurrence. Understanding the underlying molecular mechanisms of CRC tumorigenesis and metastasis has become increasingly important. Recently, aberrant Wnt/β‑catenin signaling has been reported to be strongly associated with CRC tumorigenesis, metastasis and recurrence. Therefore, the Wnt/β‑catenin signaling pathway has potential value as a therapeutic target for CRC. In the present review, the dysregulation of this pathway in CRC and the promoting or suppressing function of therapeutic targets on CRC were explored. In addition, the interaction between this pathway and epithelial‑mesenchymal transition (EMT), cell stemness, mutations, metastasis‑related genes and tumor angiogenesis in CRC cells were also investigated. Numerous studies on this pathway may help identify the potential diagnostic and prognostic markers and therapeutic targets for CRC.

Multifaced roles of PLAC8 in cancer

The role of PLAC8 in tumorigenesis has been gradually elucidated with the development of research. Although there are common molecular mechanisms that enforce cell growth, the impact of PLAC8 is varied and can, in some instances, have opposite effects on tumorigenesis. To systematically understand the role of PLAC8 in tumors, the molecular functions of PLAC8 in cancer will be discussed by focusing on how PLAC8 impacts tumorigenesis when it arises within tumor cells and how these roles can change in different stages of cancer progression with the ultimate goal of suppressing PLAC8-relevant cancer behavior and related pathologies. In addition, we highlight the diversity of PLAC8 in different tumors and its functional output beyond cancer cell growth. The comprehension of PLAC8's molecular function might provide new target and lead to the development of novel anticancer therapies.

Cancer Cells Retrace a Stepwise Differentiation Program during Malignant Progression

Pancreatic neuroendocrine tumors (PanNET) comprise two molecular subtypes, relatively benign islet tumors (IT) and invasive, metastasis-like primary (MLP) tumors. Until now, the origin of aggressive MLP tumors has been obscure. Herein, using multi-omics approaches, we revealed that MLP tumors arise from IT via dedifferentiation following a reverse trajectory along the developmental pathway of islet β cells, which results in the acquisition of a progenitor-like molecular phenotype. Functionally, the miR-181cd cluster induces the IT-to-MLP transition by suppressing expression of the Meis2 transcription factor, leading to upregulation of a developmental transcription factor, Hmgb3. Notably, the IT-to-MLP transition constitutes a distinct step of tumorigenesis and is separable from the classic proliferation-associated hallmark, temporally preceding accelerated proliferation of cancer cells. Furthermore, patients with PanNET with elevated HMGB3 expression and an MLP transcriptional signature are associated with higher-grade tumors and worse survival. Overall, our results unveil a new mechanism that modulates cancer cell plasticity to enable malignant progression. SIGNIFICANCE: Dedifferentiation has long been observed as a histopathologic characteristic of many cancers, albeit inseparable from concurrent increases in cell proliferation. Herein, we demonstrate that dedifferentiation is a mechanistically and temporally separable step in the multistage tumorigenesis of pancreatic islet cells, retracing the developmental lineage of islet β cells.This article is highlighted in the In This Issue feature, p. 2355.

PLAC8 gene knockout increases the radio-sensitivity of xenograft tumors in nude mice with nasopharyngeal carcinoma by promoting apoptosis

In vitro cell experiments showed that knocking out the placenta-specific protein 8 (PLAC8) gene significantly increased the sensitivity of tumor cells to radiation. This study used two nude mouse models of nasopharyngeal carcinoma (NPC) to investigate the radio-sensitization and molecular mechanism of PLAC8 knockout in vivo. The expression of PLAC8 in 120 NPC tissues and 30 nasopharyngitis (NPG) tissues was detected by immunohistochemistry (IHC) to analyze the relationship between PLAC8 and neck lymph node metastasis and prognosis in NPC patients. The mRNA expression level of PLAC8 in several NPC cell lines was detected by semi-quantitative RT-PCR. The PLAC8 gene was knocked out in CNE-2 cells using CRISPR/Cas9. The effect of PLAC8 gene knockout on the radiotherapy sensitivity of NPC cells was analyzed by establishing model 1 and model 2 tumor-bearing nude mouse models with two different irradiation methods. The expression of γH2AX, Bax, Bcl-2, Caspase-3 and cleaved Caspase-3 was detected by immunofluorescence (IF), IHC and western blot analysis. PLAC8 expression was significantly increased in NPC tissue samples and NPC cell lines compared with NPG tissue samples and normal cell lines (P<0.01). PLAC8 upregulation was associated with lymph node metastasis and a poor prognosis in patients with NPC (P<0.01). Both animal models showed that radiotherapy after PLAC8 knockout significantly slowed tumor growth and reduced tumor volume, with tumor inhibition rates of 100% and 66.04%, respectively. In model 2, PLAC8 knockout with radiotherapy increased the expressions of γH2AX, Bax, Caspase-3 and cleaved Caspase-3 but decreased the expression of Bcl-2 (P<0.01). In model 1, there was no tumor formation at the site where the cancer cells were injected. The expression levels of γH2AX, Bax, Caspase-3 and cleaved Caspase-3 in skin tissues taken at the injection site were lower than those in NPC tissues treated with radiotherapy, while the expression level of Bcl-2 was higher (P<0.01). PLAC8 expression is closely related to neck metastasis and the prognosis of NPC. PLAC8 gene knockout significantly increases the radio-sensitivity of NPC cells in vivo by promoting apoptosis, which is an effective strategy for the radiotherapy sensitization of NPC.

Id4 Suppresses the Growth and Invasion of Colorectal Cancer HCT116 Cells through CK18-Related Inhibition of AKT and EMT Signaling

Id4 is one of the inhibitors of DNA-binding proteins (Id) and involved in the pathogenesis of numerous cancers. The specific mechanism underlying the Id4-mediated regulation of proliferation, invasion, and metastasis of colorectal cancer (CRC) cells is still largely unclear. In the present study, results showed CRC cells had a lower baseline Id4 expression than normal intestinal epithelial NCM460 cells. In order to explore the role of Id4 in the tumorigenicity, CRC HCT116 cells with stable Id4 expression were used, and results showed Id4 overexpression arrested the cell cycle at the G0/G1 phase, inhibited the cell proliferation and the colony formation, as well as suppressed the migration and invasion. In the in vivo model, Id4 overexpression inhibited the tumor growth and metastasis in the nude mice. Furthermore, Id4 overexpression upregulated the expression of proteins associated with cell proliferation, inhibited the PI3K/AKT pathway, and suppressed epithelial-mesenchymal transition (EMT) of HCT116 cells. Moreover, Id4 significantly decreased cytokeratin 18 (CK18) expression, but CK18 overexpression in Id4 expressing HCT116-Id4 cells rescued the activation of AKT, p-AKT, MMP2, MMP7, and E-cadherin. Collectively, our study indicated Id4 may inhibit CRC growth and metastasis through inhibiting the PI3K/AKT pathway in a CK18-dependent manner and suppressing EMT. Id4 may become a target for the treatment of CRC.

Clinicopathological Significances of Cancer Stem Cell-Associated HHEX Expression in Breast Cancer

Aberrant expression of the transcription factor hematopoietic ally expressed homeobox/proline-rich homeodomain (HHEX/PRH) is implicated in numerous cancers. However, the association of HHEX with breast cancer (BC) remains unclear. In this study, HHEX mRNA and protein expression were analyzed using the Oncomine, UALCAN, GEPIA, TCGAportal, and HPA databases. We evaluated the effect of HHEX on clinicopathological parameters using Kaplan–Meier plotter, OncoLnc, TCGAportal, PROGgeneV2, and BC-GenExMiner. Western blotting was performed to compare the level of HHEX in breast samples of Tientsin Albino 2 mice, human breast precancerous lesions, benign breast tumors, and BC. The correlation between HHEX and cancer stem cells was investigated using the GEO (GSE52327 and GSE94865) and GEPIA datasets. Networks between HHEX and survival-related gene marker sets and microRNAs were analyzed using GEPIA, StarBase, and Cytoscape. Results of this study showed that HHEX expression in BC was significantly lower than those in breast precancerous lesions and benign breast tumors at both mRNA and protein levels. BC patients with lower HHEX expression had significantly worse overall survival and disease-free survival. Moreover, HHEX significantly affected the clinicopathology of BC. Specifically, low HHEX expression was correlated with the following groups of patients: age ≤51 years, ER-negative or PR-negative patients, HER-2 positive, triple-negative breast cancer, and basal-like BC. Immunohistochemical analysis of the breast samples showed significant differences of HHEX staining index (P < 0.001) among the three groups. To further investigate the mechanism, we determined the intersection of differentially expressed genes related to BC stem cells and those genes after HHEX expression was altered. This led to the identification of four potentially regulated genes-CXL12, BLNK, PAG1, and LPXN. Using StarBase and km-plotter, the negative regulation of HHEX expression and survival trends, including miR-130b, miR-30e, and miR-301b were joined into miRNA-HHEX-mRNA potential regulatory network. The abilities of proliferation, migration and invasion increased in MDA-MB-231 and BT-549 breast cancer cell lines after HHEX down expression and decreased after HHEX overexpression compared them in the control cells. In conclusion, these data suggest that HHEX expression is downregulated in BC and HHEX may regulate the development of BC through the stem cell-related genes.

Wnt-regulating microRNAs role in gastric cancer malignancy

Gastric cancer (GC) is responsible for high morbidity and mortality worldwide. This cancer claims fifth place among other cancers. There are a number of factors associated with GC development such as alcohol consumption and tobacco smoking. It seems that genetic factors play significant role in GC malignancy and progression. MicroRNAs (miRs) are short non-coding RNA molecules with negative impact on the expression of target genes. A variety of studies have elucidated the potential role of miRs in GC growth. Investigation of molecular pathways has revealed that miRs function as upstream modulators of Wnt signaling pathway. This signaling pathway involves in important biological processes such as cell proliferation and differentiation, and its dysregulation is associated with GC invasion. At the present review, we demonstrate that how miRs regulate Wnt signaling pathway in GC malignancy.

IL-1β Promotes Stemness of Tumor Cells by Activating Smad/ID1 Signaling Pathway

Background: IL-1β is reported to be involved in cancer development and distant metastasis. However, the underlying mechanism of IL-1β upon malignant behaviors remains largely unknown. In this study, we aimed to study whether IL-1β could enhance the stemness traits of tumor cells. Methods: The concentrations of serum IL-1β in head and neck squamous cell carcinoma (HNSCC) and melanoma patients were detected using ELISA assay. The effect and mechanisms of IL-1β on tumor cell growth, migration, invasion and stemness characters were studied using HNSCC cell SCC7 and melanoma cell B16-F10. The underlying mechanisms were further explored. Results: Enhanced concentrations of IL-1β were positively correlated with advanced tumor stage in both HNSCC and melanoma patients. IL-1β treatment led to a significant increase in tumor growth both in vitro and in vivo. IL-1β stimulation promoted cell proliferation, colony formation and tumorigenicity. In addition, IL-1β-stimulated tumor cells gained enhanced capabilities on wounding healing and invasion capabilities. Moreover, IL-1β stimulation promoted the stem-like capabilities of both HNSCC cells and melanoma cells, including the enrichment of aldehyde dehydrogenase⁺ (ALDH⁺) cells, up-regulation of stem cell related markers Nanog, OCT4, and SOX2, sphere formation and chemoresistance. Mechanistically, IL-1β treatment promoted the phosphorylation of Smad1/5/8 and activated its downstream target inhibitor of differentiation 1 (ID1). Silencing ID1 abrogated sphere formation and upregulated expression of stemness genes which were induced by IL-1β stimulation. Conclusion: Our data demonstrates that IL-1β promotes the stemness of HNSCC and melanoma cells through activating Smad/ID1 signal pathway.

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.