PROX1 Promotes Secretory Granule Formation in Medullary Thyroid Cancer Cells

PROX1 is a regulator of neuroendocrine-related gene expression in lung carcinoid

Lung neuroendocrine neoplasms (NENs) are a diverse group of tumors characterized by neuroendocrine (NE) differentiation. Among lung NENs, lung carcinoid (LC) is a rare tumor with unique characteristics. Recent research has highlighted the importance of transcription factors (TFs) in establishing gene expression programs in lung NENs such as small cell lung carcinoma. However, the TFs that control the gene expression of LC are largely unknown. In this study, we report the expression and potential function of a TF called Prospero homeobox protein1 (PROX1) in LC. Publicly available transcriptome data suggested that PROX1 was highly expressed in LC tissues, which was confirmed by immunohistochemical analysis on a tissue microarray. Knockdown of PROX1 did not impact the cellular viability of an LC-derived cell line, NCI-H727. Meanwhile, transcriptome analysis revealed that PROX1 knockdown altered the expression of genes involved in NE differentiation. ASCL1, CHGA, CALCA, and LINC00261 were suggested as downstream genes of PROX1. These findings indicate that PROX1 may play an important role in the NE identity of LC by regulating the expression of key target genes.

Ubiquitin C-terminal hydrolase L1 promotes lymph node metastasis in small cell neuroendocrine carcinomas of the cervix

Objective

To screen for specific differentially expressed genes in small cell neuroendocrine carcinoma of the cervix (SCNEC) and to further explore their roles and mechanisms in tumor progression.

Methods

Differentially expressed genes in SCNEC compared with squamous cell carcinoma (SCC) and adenocarcinoma (AC) were screened by microarray and immunohistochemical analyses. The biological functions of the identified genes were examined in a SCNEC cell line using RNA interference and over-expression plasmid-transfection technologies. Co-expression network analysis and immunoprecipitation technology were used to explore the potential mechanisms.

Results

Compared with SCC and AC, UCHL1 (encoding ubiquitin C-terminal hydrolase L1) was identified as a specific differentially expressed gene in SCNEC, which was positively related to lymph node metastasis (LNM). Migration and invasion of SCNEC tumor cells were induced by UCHL1 over-expression and suppressed by UCHL1 down-regulation, as shown by scratch and transwell invasion assays. Co-expression network analysis suggested that Prospero homeobox protein 1 (PROX1) might interact with UCHL1, and in vivo immunoprecipitation and western blots verified that levels of ubiquitinated PROX1 were significantly decreased following UCHL1 overexpression.

Conclusion

UCHL1 is a potential biomarker of LNM in SCNEC. UCHL1 might promote SCNEC cell migration and invasion by reducing PROX1 ubiquitination.

Endocrine secretory granule production is caused by a lack of REST and intragranular secretory content and accelerated by PROX1

Endocrine secretory granules (ESGs) are morphological characteristics of endocrine/neuroendocrine cells and store peptide hormones/neurotransmitters. ESGs contain prohormones and ESG-related molecules, mainly chromogranin/secretogranin family proteins. However, the precise mechanism of ESG formation has not been elucidated. In this study, we experimentally induced ESGs in the non-neuroendocrine lung cancer cell line H1299. Since repressive element 1 silencing transcription factor (REST) and prospero homeobox 1 (PROX1) are closely associated with the expression of ESG-related molecules, we edited the REST gene and/or transfected PROX1 and then performed molecular biology, immunocytochemistry, and electron and immunoelectron microscopy assays to determine whether ESG-related molecules and ESGs were induced in H1299 cells. Although chromogranin/secretogranin family proteins were induced in H1299 cells by knockout of REST and the induction was accelerated by the PROX1 transgene, the ESGs could not be defined by electron microscopy. However, a small number of ESGs were detected in the H1299 cells lacking REST and expressing pro-opiomelanocortin (POMC) by electron microscopy. Furthermore, many ESGs were produced in the REST-lacking and PROX1- and POMC-expressing H1299 cells. These findings suggest that a lack of REST and the expression of genes related to ESG content are indispensable for ESG production and that PROX1 accelerates ESG production.

Trial registration: Not applicable.

ASCL1, NKX2-1, and PROX1 co-regulate subtype-specific genes in small-cell lung cancer

Lineage-defining transcription factors (LTFs) play key roles in small-cell lung cancer (SCLC) pathophysiology. Delineating the LTF-regulated genes operative in SCLC could provide a road map to identify SCLC dependencies. We integrated chromatin landscape and transcriptome analyses of patient-derived SCLC preclinical models to identify super-enhancers (SEs) and their associated genes in the ASCL1-, NEUROD1-, and POU2F3-high SCLC subtypes. We find SE signatures predict LTF-based classification of SCLC, and the SE-associated genes are enriched with those defined as common essential genes in DepMap. In addition, in ASCL1-high SCLC, we show ASCL1 complexes with NKX2-1 and PROX1 to co-regulate genes functioning in NOTCH signaling, catecholamine biosynthesis, and cell-cycle processes. Depletion of ASCL1 demonstrates it is a key dependency factor in preclinical SCLC models and directly regulates multiple DepMap-defined essential genes. We provide LTF/SE-based subtype-specific gene sets for SCLC for further therapeutic investigation.

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Super-enhancers support lineage-defining transcription factor SCLC classification

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SCLC super-enhancer-associated genes represent essential and lineage-identity genes

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ASCL1, NKX2-1, and PROX1 proteins interact in a complex in SCLC-A

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ASCL1, NKX2-1, and PROX1 regulate Notch-signaling, NE-specific, and cell-cycle genes

The association of transcription factor Prox1 with the proliferation, migration, and invasion of lung cancer

Background

The current study investigates the effect of transcription factor Prox1 on the proliferation, migration, and invasion ability of lung cancer.

Methods

Lung cancer cell lines (A549 and H446 cells) were transfected with Prox1NAD and siRNA, respectively. Thus, the A549 and H446 cells overexpressed Prox1 after transfection of Prox1NAD plasmids, and A549 and H446 cells have low expression of Prox1 after transfection with siRNA. Reverse transcriptase quantitative PCR and western blot analyses were used to detect Prox1 mRNA and protein expression in cells. Plate clone formation experiments and MTT experiments were used to detect cell proliferation. Western blot was used to detect the expression of Rho family-related proteins in cells.

Results

Compared to untransfected wild-type A549 and H446 that served as blank controls, the expression level of Prox1mRNA and protein in A549 and H446 cells overexpressing Prox1 after plasmid transfection was high, while the expression level of Prox1mRNA and protein in A549 and H446 cells with low expression of Prox1 after siRNA transfection was low. With the increase of Prox1 expression, the expression of RhoA and RhoC increased, while the expression of RhoB decreased.

Conclusion

The finding of this study may provide a new approach for the treatment of lung cancer using targeted gene therapy.

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

Transcription factor Prospero homeobox 1 (PROX1) is continuously expressed in the lymphatic endothelial cells, playing an essential role in their differentiation. Many reports have shown that PROX1 is implicated in cancer development and acts as an oncoprotein or suppressor in a tissue-dependent manner. Additionally, the PROX1 expression in many types of tumors has prognostic significance and is associated with patient outcomes. In our previous experimental studies, we showed that PROX1 is present in the thyroid cancer (THC) cells of different origins and has a high impact on follicular thyroid cancer (FTC) phenotypes, regulating migration, invasion, focal adhesion, cytoskeleton reorganization, and angiogenesis. Herein, we discuss the PROX1 transcript and protein structures, the expression pattern of PROX1 in THC specimens, and its epigenetic regulation. Next, we emphasize the biological processes and genes regulated by PROX1 in CGTH-W-1 cells, derived from squamous cell carcinoma of the thyroid gland. Finally, we discuss the interaction of PROX1 with other lymphatic factors. In our review, we aimed to highlight the importance of vascular molecules in cancer development and provide an update on the functionality of PROX1 in THC biology regulation.

Expression of Prox1 in Medullary Thyroid Carcinoma Is Associated with Chromogranin A and Calcitonin Expression and with Ki67 Proliferative Index, but Not with Prognosis

Medullary thyroid carcinoma (MTC) has been shown to express Prospero homeobox protein 1 (Prox1), a transcription factor whose expression is altered in a variety of human cancers. We conducted a retrospective study on a series of 32 patients with MTC to test the correlation of Prox1 expression in MTC with clinicopathological features and to evaluate its prognostic significance. Correlation of Prox1 immunohistochemical expression with tumor size, proliferative index (Ki67), and calcitonin and CEA serum levels prior to surgery was tested for significant correlations. The difference in Prox1 and Ki67 immunohistochemical expression according to the immunohistochemical staining intensity of CEA, chromogranin A, and calcitonin was tested using the Kruskal-Wallis H test and linear regression analysis. The prognostic value of Prox1 and Ki67 for our patient cohort was assessed by Kaplan-Meier log rank survival analysis. We demonstrated a positive correlation between Prox1 expression and Ki67 index. Prox1 also showed significant difference in expression according to chromogranin A and calcitonin immunohistochemical expression, with higher Prox1 expression in tumors with stronger chromogranin A or calcitonin staining. Prox1 expression did not correlate with PFS or OS based on Kaplan-Meier log rank survival analysis. In conclusion, Prox1 expression in MTC is positively correlated with Ki67 and with the immunohistochemical expression of chromogranin A and calcitonin. However, the present study does not support a role for Prox1 in MTC prognosis.

A novel gene-pair signature for relapse-free survival prediction in colon cancer

Background

Colon cancer (CC) patients with early relapse usually have a poor prognosis. In this study, we aimed to identify a novel signature to improve the prediction of relapse-free survival (RFS) in CC.

Methods

Four microarray datasets were merged into a training set (n=1,045), and one RNA-sequencing dataset was used as a validation set (n=384). In the training set, microarray meta-analysis screened out 596 common RFS-related genes across datasets, which were used to construct 177,310 gene pairs. Then, the LASSO penalized generalized linear model identified 16 RFS-related gene pairs, and a risk score was calculated for each sample according to the model coefficients.

Results

The risk score demonstrated a good ability in predicting RFS (area under the curve [AUC] at 5 years: 0.724; concordance index [C-index]: 0.642, 95% CI: 0.615–0.669). High-risk patients showed a poorer prognosis than low-risk patients (HR: 3.519, 95% CI: 2.870–4.314). Subgroup analysis reached consistent results when considering multiple confounders. In the validation set, the risk score had a similar performance (AUC at 5 years: 0.697; C-index: 0.696, 95% CI: 0.627–0.766; HR: 2.926, 95% CI: 1.892–4.527). When compared with a 13-gene signature, a 15-gene signature, and TNM stage, the score showed a better performance (P<0.0001; P=0.0004; P=0.0125), especially for the patients with a longer follow-up (R2=0.988, P<0.0001). When the follow-up was >5 years (n=314), the score demonstrated an excellent performance (C-index: 0.869, 95% CI: 0.816–0.922; HR: 13.55, 95% CI: 7.409–24.78).

Conclusion

Our study identified a novel gene-pair signature for prediction of RFS in CC.

Sporadic minute medullary thyroid carcinoma with a double RET mutation: A case report

We describe a 74-year-old man with a nodular goiter accompanied by an incidental sporadic minute medullary thyroid carcinoma (MTC). Histopathologically, the MTC was a well-defined 1.7 mm tumor in the upper one-third right lobe, with solid cell nests (SCNs) adjacent to the MTC. C-cells were scattered mainly around the SCNs, but C-cell hyperplasia was not evident in the background thyroid. The MTC cell phenotype was immunohistochemically identical to background C-cells, but was completely different from the SCN main cells. Direct DNA analyses of isolated MTC paraffin-embedded specimens revealed two RET proto-oncogene missense point mutations in exon 11 (i.e., C630R and C634W). The non-tumor thyroid tissue did not reveal any mutations. This study reports the smallest case of sporadic MTC with a double RET somatic mutation, substantiating that RET mutations can occur during a very early stage of carcinogenesis. The combined presence of C630R and C634W represent a novel somatic mutation in sporadic MTC. The present case indicates that the sporadic MTC originated from the surrounding C-cells of the SCNs without C-cell hyperplasia and that the SCN main cells may not be able to develop into an MTC.

Role of tumor microenvironment in tumorigenesis

Tumorigenesis is a complex and dynamic process, consisting of three stages: initiation, progression, and metastasis. Tumors are encircled by extracellular matrix (ECM) and stromal cells, and the physiological state of the tumor microenvironment (TME) is closely connected to every step of tumorigenesis. Evidence suggests that the vital components of the TME are fibroblasts and myofibroblasts, neuroendocrine cells, adipose cells, immune and inflammatory cells, the blood and lymphatic vascular networks, and ECM. This manuscript, based on the current studies of the TME, offers a more comprehensive overview of the primary functions of each component of the TME in cancer initiation, progression, and invasion. The manuscript also includes primary therapeutic targeting markers for each player, which may be helpful in treating tumors.

Thyroid Progenitors Are Robustly Derived from Embryonic Stem Cells through Transient, Developmental Stage-Specific Overexpression of Nkx2-1

The clinical importance of anterior foregut endoderm (AFE) derivatives, such as thyrocytes, has led to intense research efforts for their derivation through directed differentiation of pluripotent stem cells (PSCs). Here, we identify transient overexpression of the transcription factor (TF) NKX2-1 as a powerful inductive signal for the robust derivation of thyrocyte-like cells from mouse PSC-derived AFE. This effect is highly developmental stage specific and dependent on FOXA2 expression levels and precise modulation of BMP and FGF signaling. The majority of the resulting cells express thyroid TFs (Nkx2-1, Pax8, Foxe1, Hhex) and thyroid hormone synthesis-related genes (Tg, Tpo, Nis, Iyd) at levels similar to adult mouse thyroid and give rise to functional follicle-like epithelial structures in Matrigel culture. Our findings demonstrate that NKX2-1 overexpression converts AFE to thyroid epithelium in a developmental time-sensitive manner and suggest a general methodology for manipulation of cell-fate decisions of developmental intermediates.