The Impact of Transcription Factor Prospero Homeobox 1 on the Regulation of Thyroid Cancer Malignancy

Impact of Prospero Homeobox-1 (PROX-1) οn the Oncogenic Phenotypes of Hepatocellular Carcinoma Cells

BACKGROUND/AIM

Transcriptional factor prospero homeobox-1 (PROX-1) is crucial for the embryonic development of various organs and cell fate specification. It exhibits either an oncogenic or tumor suppressive activity depending on cancer types. However, the relationship between PROX-1 and hepatocellular carcinoma (HCC) remains obscure. This study was conducted to investigate the effect of PROX-1 on the invasive and oncogenic phenotypes of human HCC cells.

MATERIALS AND METHODS

The effect of PROX-1 on tumor cell behavior was investigated by using a pcDNA-myc vector and a small interfering RNA in HepG2 and Huh7 human HCC cell lines. Flow cytometry, migration, invasion, proliferation, and tube formation assays were performed. PROX-1 expression in human HCC cells was explored by western blotting.

RESULTS

PROX-1 overexpression enhanced tumor cell proliferation and inhibited apoptosis and cell cycle arrest by modulating the activities of caspase-3, PARP, and cyclin-dependent kinase inhibitors, including p21, p27, and p57 in HCC cells. After PROX-1 overexpression, the number of migrating and invading HCC cells significantly increased, and the expression levels of N-cadherin and Snail increased in HCC cells. PROX-1 overexpression enhanced angiogenesis through increased VEGF-A and VEGF-C expression and decreased angiostatin expression. PROX-1 overexpression also increased the phosphorylation of glycogen synthase kinase-3β (GSK-3β) and forkhead box O1 (FOXO1) in HCC cells. After PROX-1 knockdown, their phosphorylation was reversed.

CONCLUSION

PROX-1 overexpression is associated with the invasive and oncogenic phenotypes of human HCC cells via GSK-3β and FOXO1 phosphorylation.

Predicting the prognosis of glioma patients with TERT promoter mutations and guiding the specific immune profile of immune checkpoint blockade therapy

The telomerase reverse transcriptase promoter (TERTp) is frequently mutated in gliomas. This study sought to identify immune biomarkers of gliomas with TERTp mutations. Data from TCGA were used to identify and validate survival-associated gene signatures, and immune and stromal scores were calculated using the ESTIMATE algorithm. High stromal or immune scores in patients with TERTp-mutant gliomas correlated with shorter overall survival compared to cases with low stromal or immune scores. Among TERTp-mutant gliomas with both high immune and high stromal scores, 213 commonly shared DEGs were identified. Among 71 interacting DEGs representing candidate hub genes in a PPI network, HOXC6, WT1, CD70, and OTP showed significant ability in establishing subgroups of high- and low-risk patients. A risk model based on these 4 genes showed strong prognostic potential for gliomas with mutated TERTp, but was inapplicable for TERTp-wild-type gliomas. TERTp-mutant gliomas with high-risk scores displayed a greater percentage of naïve B cells, plasma cells, naïve CD4 T cells, and activated mast cells than low-risk score gliomas. TIDE analysis indicated that immune checkpoint blockade (ICB) therapy may benefit glioma patients with TERTp mutations. The present risk model can help predict prognosis of glioma patients with TERTp mutations and aid ICB treatment options.

Multi-Omics and Management of Follicular Carcinoma of the Thyroid

Follicular thyroid carcinoma (FTC) is the second most common cancer of the thyroid gland, accounting for up to 20% of all primary malignant tumors in iodine-replete areas. The diagnostic work-up, staging, risk stratification, management, and follow-up strategies in patients who have FTC are modeled after those of papillary thyroid carcinoma (PTC), even though FTC is more aggressive. FTC has a greater propensity for haematogenous metastasis than PTC. Furthermore, FTC is a phenotypically and genotypically heterogeneous disease. The diagnosis and identification of markers of an aggressive FTC depend on the expertise and thoroughness of pathologists during histopathological analysis. An untreated or metastatic FTC is likely to de-differentiate and become poorly differentiated or undifferentiated and resistant to standard treatment. While thyroid lobectomy is adequate for the treatment of selected patients who have low-risk FTC, it is not advisable for patients whose tumor is larger than 4 cm in diameter or has extensive extra-thyroidal extension. Lobectomy is also not adequate for tumors that have aggressive mutations. Although the prognosis for over 80% of PTC and FTC is good, nearly 20% of the tumors behave aggressively. The introduction of radiomics, pathomics, genomics, transcriptomics, metabolomics, and liquid biopsy have led to improvements in the understanding of tumorigenesis, progression, treatment response, and prognostication of thyroid cancer. The article reviews the challenges that are encountered during the diagnostic work-up, staging, risk stratification, management, and follow-up of patients who have FTC. How the application of multi-omics can strengthen decision-making during the management of follicular carcinoma is also discussed.

Homeobox Protein PROX1 Expression is Negatively Regulated by Histone Deacetylase 1 and c-JUN Complex in MDA-MB-231 Human Breast Cancer Cells

Prospero homeobox 1 (PROX1) is a member of the homeobox transcription factor family that plays a critical role in the development of multiple tissues and specification of cell fate. PROX1 expression is differentially regulated based on the cellular context and plays an antagonistic role as a tumour promoter or suppressor in different tumour types. In human breast cancer, PROX1 expression is suppress-ed; however, the molecular mechanism by which it is down-regulated remains poorly understood. Here, we show that ectopic expression of PROX1 reduces the motility and invasiveness of MDA-MB-231 human breast cancer cells, suggesting that PROX1 functions as a negative regulator of tumour invasion in MDA-MB-231 cells. Treatment with histone deacetylase (HDAC) inhibitors up-regulates PROX1 mRNA and protein expression levels. Knockdown of HDAC1 using short hairpin RNA also up-regulates PROX1 mRNA and protein expression levels. We found that HDAC1 interacted with c-JUN at the activator protein (AP)-1-binding site located at -734 to -710 in the PROX1 promoter region to suppress PROX1 expression. In addition, c-JUN N-terminal kinase-mediated c-JUN phosphorylation was found to be crucial for silencing PROX1 expression. In conclusion, PROX1 expression can be silenced by the epigenetic mechanism involved in the complex formation of HDAC1 and c-JUN at the AP-1 site in the PROX1 promoter region in MDA-MB-231 human breast cancer cells. Therefore, this study revealed the epigenetic regulatory mechanism involved in the suppression of PROX1 expression in breast cancer cells.

The Role of PROX1 in Neoplasia: A Key Player Often Overlooked

The human PROX1 gene (Prospero homeobox gene 1) is a member of the homeobox transcription factor family. PROX1 plays a key role in the development of the lymphatic system and is primarily used as a lymphatic vessel marker. However, as the accumulating evidence indicates that PROX1 is also implicated in the tumorigenesis of various cancer types, the scientific community has attempted to elucidate its complicated function in neoplasia pathogenesis, as well as its utility in cancer diagnosis, prognosis, and therapy. PROX1 has been shown to participate in the complex molecular mechanisms affecting tumorigenesis and has been associated with a plethora of clinicopathological parameters, including tumor stage and patients’ overall survival. Depending on the specific organ affected, PROX1 has exhibited both tumor-promoting and tumor-suppressing properties, with its inhibition and reactivation representing possible novel therapeutic interventions, respectively. Moreover, researchers have reported PROX1 as a useful tool in the fields of diagnosis and prognosis assessment. The current study aims to summarize and present the existing data that render PROX1 a novel and useful diagnostic and prognostic biomarker, as well as a possible therapeutic target.

Prospero homeobox 1 promotes proliferation, migration, and invasion of osteosarcoma cells and its clinical significance

Osteosarcoma (OS) is the most common primary malignant bone tumor. Prospero homeobox 1 (PROX1) is a key transcription factor involved in some cancers, but the role of PROX1 in OS is unclear. This study aimed to explore the clinical and biology significance of PROX1 in OS. Fifty-four OS tissues and matched nontumor tissues were collected to explore the relationship between PROX1 expression and clinical characteristics and prognosis. qRT-PCR and immunohistochemistry were used to investigate the expression patterns of PROX1 in OS tissues and cells. CCK-8, wound healing, and transwell assays were used to detect the effects of PROX1 on the proliferation, migration, and invasion of OS cells. Transcriptome sequencing, bioinformatics analysis and qRT-PCR were used to explore the regulatory network of PROX1. PROX1 was significantly higher in OS tissues and cells compared to normal tissues and cell lines. In OS patients, high expression of PROX1 was associated with Enneking stage (P < 0.001) and M classification (P < 0.001). High PROX1 expression predicted a poorer overall survival (P = 0.0047). Compared with untreated cells, OS cells overexpressing PROX1 showed higher proliferation, migration, and invasion abilities, while knockdown of PROX1 suppressed these abilities. The results of Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that the down regulated genes were mainly enriched in TNF signaling pathway, MAPK signaling pathway, and neuroactive ligand-receptor interaction. High PROX1 expression was significantly associated with poor overall survival in OS patients. PROX1 may be a promising prognostic marker and therapeutic target for OS patients.

ZFPM2-AS1 transcriptionally mediated by STAT1 regulates thyroid cancer cell growth, migration and invasion via miR-515-5p/TUSC3

Objective: Our purpose was to study the roles and molecular mechanisms of long non-coding RNA (lncRNA) ZFPM2 Antisense RNA 1 (ZFPM2-AS1) in thyroid cancer.

Methods: Firstly, the expression of ZFPM2-AS1, miR-515-5p and TUSC3 was detected in thyroid cancer tissues and cells. Secondary, their biological functions (proliferation, apoptosis, migration and invasion) were analyzed by a serious of functional experiments including cell counting kit-8 (CCK-8), clone formation, 5-Ethynyl-2'-deoxyuridine (EdU), enzyme-linked immunosorbent assay (ELISA), wound healing and Transwell assays. Thirdly, the mechanisms of STAT1/ZFPM2-AS1 and ZFPM2-AS1/miR-515-5p/TUSC were validated using chromatin immunoprecipitation (CHIP), pull-down and luciferase reporter assays.

Results: ZFPM2-AS1 and TUSC were both highly expressed and miR-515-5p was down-regulated in thyroid cancer tissues as well as cells. Their knockdown weakened thyroid cancer cell growth, migration, and invasion. ZFPM2-AS1 was mainly distributed in the nucleus and cytoplasm of thyroid cancer cells. Mechanistically, up-regulation of ZFPM2-AS1 was induced by transcription factor STAT1 in line with CHIP and luciferase reporter assays. Furthermore, as a sponge of miR-515-5p, ZFPM2-AS1 decreased the ability of miR-515-5p to inhibit TUSC3 expression by pull-down, luciferase reporter and gain-and-loss assays, thereby promoting malignant progression of thyroid cancer.

Conclusion: ZFPM2-AS1 acted as an oncogene in thyroid cancer, which was transcriptionally mediated by STAT1. Furthermore, ZFPM2-AS1 weakened the inhibitory effect of miR-515-5p on TUSC3. Thus, ZFPM2-AS1 could be an underlying biomarker for thyroid cancer.

Cell and Molecular Biology of Thyroid Disorders 2.0

This issue is the second volume of the previous Special Issue, "Cell and Molecular Biology of Thyroid Disorders" [...].

Cancer and SOX proteins: New insight into their role in ovarian cancer progression/inhibition

Transcription factors are potential targets in disease therapy, particularly in cancer. This is due to the fact that transcription factors regulate a variety of cellular events, and their modulation has opened a new window in cancer therapy. Sex-determining region Y (SRY)-related high-mobility group (HMG) box (SOX) proteins are potential transcription factors that are involved in developmental processes such as embryogenesis. It has been reported that abnormal expression of SOX proteins is associated with development of different cancers, particularly ovarian cancer (OC). In the present review, our aim is to provide a mechanistic review of involvement of SOX members in OC. SOX members may suppress and/or promote aggressiveness and proliferation of OC cells. Clinical studies have also confirmed the potential of transcription factors as diagnostic and prognostic factors in OC. Notably, studies have demonstrated the relationship between SOX members and other molecular pathways such as ST6Ga1-I, PI3K, ERK and so on, leading to more complexity. Furthermore, SOX members can be affected by upstream mediators such as microRNAs, long non-coding RNAs, and so on. It is worth mentioning that the expression of each member of SOX proteins is corelated with different stages of OC. Furthermore, their expression determines the response of OC cells to chemotherapy. These topics are discussed in this review to shed some light on role of SOX transcription factors in OC.