SMAD proteins directly suppress PAX2 transcription downstream of transforming growth factor-beta 1 (TGF-β1) signalling in renal cell carcinoma

The Role of the PAX Genes in Renal Cell Carcinoma

Renal cell carcinoma (RCC) is a significant oncological challenge due to its heterogeneous nature and limited treatment options. The PAX developmental gene family encodes nine highly conserved transcription factors that play crucial roles in embryonic development and organogenesis, which have been implicated in the occurrence and development of RCC. This review explores the molecular landscape of RCC, with a specific focus on the role of the PAX gene family in RCC tumorigenesis and disease progression. Of the various RCC subtypes, clear cell renal cell carcinoma (ccRCC) is the most prevalent, characterized by the loss of the von Hippel-Lindau (VHL) tumor suppressor gene. Here, we review the published literature on the expression patterns and functional implications of PAX genes, particularly PAX2 and PAX8, in the three most common RCC subtypes, including ccRCC, papillary RCC (PRCC), and chromophobe RCC (ChRCC). Further, we review the interactions and potential biological mechanisms involving PAX genes and VHL loss in driving the pathogenesis of RCC, including the key signaling pathways mediated by VHL in ccRCC and associated mechanisms implicating PAX. Lastly, concurrent with our update regarding PAX gene research in RCC, we review and comment on the targeting of PAX towards the development of novel RCC therapies.

Co-Expression of Multiple PAX Genes in Renal Cell Carcinoma (RCC) and Correlation of High PAX Expression with Favorable Clinical Outcome in RCC Patients

Renal cell carcinoma (RCC) is the most common form of kidney cancer, consisting of multiple distinct subtypes. RCC has the highest mortality rate amongst the urogenital cancers, with kidney renal clear cell carcinoma (KIRC), kidney renal papillary cell carcinoma (KIRP), and kidney chromophobe carcinoma (KICH) being the most common subtypes. The Paired-box (PAX) gene family encodes transcription factors, which orchestrate multiple processes in cell lineage determination during embryonic development and organogenesis. Several PAX genes have been shown to be expressed in RCC following its onset and progression. Here, we performed real-time quantitative polymerase chain reaction (RT-qPCR) analysis on a series of human RCC cell lines, revealing significant co-expression of PAX2, PAX6, and PAX8. Knockdown of PAX2 or PAX8 mRNA expression using RNA interference (RNAi) in the A498 RCC cell line resulted in inhibition of cell proliferation, which aligns with our previous research, although no reduction in cell proliferation was observed using a PAX2 small interfering RNA (siRNA). We downloaded publicly available RNA-sequencing data and clinical histories of RCC patients from The Cancer Genome Atlas (TCGA) database. Based on the expression levels of PAX2, PAX6, and PAX8, RCC patients were categorized into two PAX expression subtypes, PAXClusterA and PAXClusterB, exhibiting significant differences in clinical characteristics. We found that the PAXClusterA expression subgroup was associated with favorable clinical outcomes and better overall survival. These findings provide novel insights into the association between PAX gene expression levels and clinical outcomes in RCC patients, potentially contributing to improved treatment strategies for RCC.

Inflammatory Networks in Renal Cell Carcinoma

Cancer-associated inflammation has been established as a hallmark feature of almost all solid cancers. Tumor-extrinsic and intrinsic signaling pathways regulate the process of cancer-associated inflammation. Tumor-extrinsic inflammation is triggered by many factors, including infection, obesity, autoimmune disorders, and exposure to toxic and radioactive substances. Intrinsic inflammation can be induced by genomic mutation, genome instability and epigenetic remodeling in cancer cells that promote immunosuppressive traits, inducing the recruitment and activation of inflammatory immune cells. In RCC, many cancer cell-intrinsic alterations are assembled, upregulating inflammatory pathways, which enhance chemokine release and neoantigen expression. Furthermore, immune cells activate the endothelium and induce metabolic shifts, thereby amplifying both the paracrine and autocrine inflammatory loops to promote RCC tumor growth and progression. Together with tumor-extrinsic inflammatory factors, tumor-intrinsic signaling pathways trigger a Janus-faced tumor microenvironment, thereby simultaneously promoting or inhibiting tumor growth. For therapeutic success, it is important to understand the pathomechanisms of cancer-associated inflammation, which promote cancer progression. In this review, we describe the molecular mechanisms of cancer-associated inflammation that influence cancer and immune cell functions, thereby increasing tumor malignancy and anti-cancer resistance. We also discuss the potential of anti-inflammatory treatments, which may provide clinical benefits in RCCs and possible avenues for therapy and future research.

Transforming Growth Factor-β1 Regulates Peroxisomal Genes/Proteins via Smad Signaling in Idiopathic Pulmonary Fibrosis Fibroblasts and Transgenic Mouse Models

Idiopathic pulmonary fibrosis (IPF) is a chronic human disease with persistent destruction of lung parenchyma. Transforming growth factor-β1 (TGF-β1) signaling plays a pivotal role in the initiation and pathogenesis of IPF. As shown herein, TGF-β1 signaling down-regulated not only peroxisome biogenesis but also the metabolism of these organelles in human IPF fibroblasts. In vitro cell culture observations in human fibroblasts and human lung tissue indicated that peroxisomal biogenesis and metabolic proteins were significantly down-regulated in the lung of 1-month-old transgenic mice expressing a constitutively active TGF-β type I receptor kinase (ALK5). The peroxisome biogenesis protein peroxisomal membrane protein Pex13p (PEX13p) as well as the peroxisomal lipid metabolic enzyme peroxisomal acyl-coenzyme A oxidase 1 (ACOX1) and antioxidative enzyme catalase were highly up-regulated in TGF-β type II receptor and Smad3 knockout mice. This study reports a novel mechanism of peroxisome biogenesis and metabolic regulation via TGF-β1-Smad signaling: interaction of the Smad3 transcription factor with the PEX13 gene in chromatin immunoprecipitation-on-chip assay as well as in a bleomycin-induced pulmonary fibrosis model applied to TGF-β type II receptor knockout mice. Taken together, data from this study suggest that TGF-β1 participates in regulation of peroxisomal biogenesis and metabolism via Smad-dependent signaling, opening up novel strategies for the development of therapeutic approaches to inhibit progression of pulmonary fibrosis patients with IPF.

Modeling Neoplastic Growth in Renal Cell Carcinoma and Polycystic Kidney Disease

Renal cell carcinoma (RCC) and autosomal dominant polycystic kidney disease (ADPKD) share several characteristics, including neoplastic cell growth, kidney cysts, and limited therapeutics. As well, both exhibit impaired vasculature and compensatory VEGF activation of angiogenesis. The PI3K/AKT/mTOR and Ras/Raf/ERK pathways play important roles in regulating cystic and tumor cell proliferation and growth. Both RCC and ADPKD result in hypoxia, where HIF-α signaling is activated in response to oxygen deprivation. Primary cilia and altered cell metabolism may play a role in disease progression. Non-coding RNAs may regulate RCC carcinogenesis and ADPKD through their varied effects. Drosophila exhibits remarkable conservation of the pathways involved in RCC and ADPKD. Here, we review the progress towards understanding disease mechanisms, partially overlapping cellular and molecular dysfunctions in RCC and ADPKD and reflect on the potential for the agile Drosophila genetic model to accelerate discovery science, address unresolved mechanistic aspects of these diseases, and perform rapid pharmacological screens.

CircTBL1XR1/miR-424 axis regulates Smad7 to promote the proliferation and metastasis of colorectal cancer

BACKGROUND

This study analyzed the effect of circular RNA (circRNA), TBL1XR1, on the malignant progression of colon cancer cells and explored its possible molecular mechanism.

METHODS

The expression levels of circTBL1XR1 in colorectal cancer and paracancerous tissues were detected by quantitative real-time polymerase chain (qRT-PCR). Changes in circTBL1XR1 expression in normal intestinal epithelial cells and colon cancer cell lines were detected at the cellular level. LoVo and SW620 cells with the highest circTBL1XR1 expression were transfected with circTBL1XR1, and the transfection efficiency was verified by qRT-PCR. The effects of circTBL1XR1 on the proliferation, migration, and invasion of colon cancer cells were detected by MTT, Transwell migration, and invasion assay, and a subcutaneous tumor model. Target genes of circTBL1XR1 were verified by luciferase reporter assay. Expression levels of circTBL1XR1 target genes were detected by qRT-PCR and Western blotting.

RESULTS

circTBL1XR1 was highly expressed in colon cancer patients. circTBL1XR1 expression in colon cancer cells was also higher than that in normal intestinal cells. In vivo and in vitro experimental results showed that overexpression of circTBL1XR1 enhanced the proliferation, migration, and invasion of colon cancer cells. After lowering circTBL1XR1, the ability of migration and invasion of colon cancer cells was significantly reduced. Bioinformatics retrieval and luciferase reporter gene assay confirmed that circTBL1XR1 can bind to microRNA-424 (miR-424) and that the Smad7 gene is the target gene of miR-424.

CONCLUSIONS

circTBL1XR1 was highly expressed in colon cancer, and miR-424 was poorly expressed in colon cancer cells. circTBL1XR1 regulates the expression of Smad7 through miR-424, thereby affecting the malignant progression of colorectal cancer.

PAX3 silencing inhibits prostate cancer progression through the suppression of the TGF-β/Smad signaling axis

Multiple studies have confirmed the pro-oncogenic effects of PAX3 in an array of cancers, but its role in prostate cancer (PCa) remains largely undefined. The aim of this study is to investigate the role of PAX3 in PCa. PAX3 expression was compared between PCa tumor tissue and nontumor tissues and PCa cell lines and normal prostate epithelial cells (PNT2) by western blot analysis and immunohistochemistry staining. MTT and immunofluorescence assays were used to detect PCa cell proliferation. Flow cytometry was used to evaluate cell apoptosis in PCa. Transwell assays were used for the determination of cell migration and PCa cell invasion. PAX3 expression was higher in PCa tissues and human PCa cell lines. Moreover, PAX3 silencing inhibited the proliferation, metastasis, and epithelial-mesenchymal transition (EMT) of PCa cells, and increased the rates of apoptosis. PAX3 silencing inhibited transforming growth factor-β (TGF-β)/Smad signaling in PCa cells. The effects of si-PAX3 on the proliferation, apoptosis, metastasis, and EMT of PCa cells were alleviated by TGF-β1 treatment. PAX3 silencing inhibits PCa progression through the inhibition of TGF-β/Smad signaling. This reveals PAX3 as a novel biomarker and therapeutic target for future PCa treatments.

Molecular Mechanism of Mesenchyme Homeobox 1 in Transforming Growth Factor β1-Induced P311 Gene Transcription in Fibrosis

Organ fibrosis is characterized by excessive fibroblast, and extracellular matrix and the molecular basis are not fully elucidated. Recent studies have proven that P311, an 8-kDa conserved protein, could promote various organ fibrosis, such as skin, kidney, liver, and lung, partially through upregulating transforming growth factor β1 (TGF-β1) translation. However, the upstream regulators and mechanism of P311 gene regulation remain unclear, although we previously found that cytokines, hypoxia, and TGF-β1 could upregulate P311 transcription. Here, we aimed to elucidate the molecular mechanism of TGF-β1–induced P311 transcriptional regulation, focusing on mesenchyme homeobox 1 (Meox1). In this article, we identified the core promoter of P311 through bioinformatics analysis and luciferase reporter assays. Moreover, we demonstrated that Meox1, induced by TGF-β1, could bind to the promoter of P311 and promote its transcriptional activity. Furthermore, the effect of Meox1 on P311 transcriptional expression contributed to altered migration and proliferation in human dermal fibroblast cells. In conclusion, we identified Meox1 as a novel transcription factor of P311 gene, providing a new clue of the pathogenesis in fibrosis.

Diosgenin inhibits the epithelial-mesenchymal transition initiation in osteosarcoma cells via the p38MAPK signaling pathway

Diosgenin is an important basic raw material for the production of steroid hormone drugs. It can be isolated and purified from a variety of traditional Chinese medicines or plants. Modern molecular biological studies have shown that diosgenin inhibits various tumor cells migration and invasion ability to varying degrees in vitro and in vivo. The aim of the present study was to observe the inhibitory effects of diosgenin on the invasive and metastatic capabilities of osteosarcoma cells and to determine the association between the effects of diosgenin on the epithelial-mesenchymal transition (EMT). Wound healing and Transwell assays were used to observe the inhibitory effects of diosgenin on the invasion and migration of two osteosarcoma cell lines. Immunofluorescence was used to observe changes in transforming growth factor β1 (TGF-β1) protein expression levels in the osteosarcoma cells following drug administration. EMT-associated proteins, including TGFβ1, E-cadherin and vimentin were detected by western blotting, which demonstrated that the drug may inhibit the initiation of EMT in osteosarcoma cells. Western blot analysis of the expression of all the proteins in the mitogen-activated protein kinase (MAPK) pathway demonstrated that the drug inhibited the MAPK signaling pathway. The primary mechanism of action of diosgenin was the inhibition of the phosphorylated p38 (pP38) protein. Through a combination of inhibitors of the p38MAPK signaling pathway and detection of the downstream EMT marker protein E-cadherin by quantitative PCR, pP38 was confirmed to be a target of diosgenin in the inhibition of EMT in the osteosarcoma cells via the MAPK molecular signaling pathway. Diosgenin may exhibit utility as an auxiliary drug for the clinical reduction of metastasis in patients with osteosarcoma.

miR-106b promotes proliferation and invasion by targeting Capicua through MAPK signaling in renal carcinoma cancer

Background: miR-106b has been reported to play a vital role in pathogenesis of some types of cancer, whilst the role of miR-106b in renal carcinoma cancer (RCC) remains unknown. Purpose: The objective of this study was to identify the mechanism of miR-106b regulating the progression of renal carcinoma. Method: The expression of miR-106b was analyzed in RCC cell lines, RCC and adjacent normal renal tissues through qRT-PCR assays. Target mRNA of miR-106b was predicted with databases and verified by luciferase reporter assays. And the effects of miR-106b or targeted mRNA on cell proliferation, invasion, the process of epithelial-mesenchymal transitions (EMTs) were assessed in vitrothrough CCK-8, transwell cell invasion assays, qRT-PCR and Western blotting assays respectively. In addition, the effects of miR-106b on the growth of xenografts mice were analyzedin vivo. Results: The results demonstrated that miR-106b was significantly increased both in RCC tissues and cell lines. Luciferase reporter assays revealed that miR-106b inhibited Capicua expression by targeting its 3'-UTR sequence. And miR-106b promoted cell proliferation, invasion, EMT progression in RCC cellin vitro, as well as promoted the tumor growth of 786-O cells derived xenografts mice. Additionally, loss of Capicua promoted the activation of MAPK signaling pathway. Conclusion: The study suggested that miR-106b regulated RCC progression through MAPK signaling pathway partly by targeting Capicua, which might provide valuable evidence for therapeutic target development of RCC.

Long Non-Coding RNA TFAP2A-AS1 Inhibits Cell Proliferation and Invasion in Breast Cancer via miR-933/SMAD2

BACKGROUND It is well documented that long non-coding RNAs (lncRNAs) are involved in the progression of multiple human tumors by sponging microRNAs (miRNAs). However, whether lncRNA TFAP2A-AS1 plays a role in the tumorigenesis of breast cancer (BC) remains undetermined. MATERIAL AND METHODS Real-time PCR (qRT-PCR) assay was performed to detect the relative mRNA expression of TFAP2A-AS1 and miR-933. Flow cytometry analysis, CCK-8 assay, and Transwell assay were applied to detect the effects of TFAP2A-AS1 overexpression on cell cycle, apoptosis, viability, and invasion of BC cells. In vivo proliferation assay was performed to evaluate the effects of TFAP2A-AS1 overexpression on tumor growth. Bioinformatics methods, dual-luciferase reporter, RNA immunoprecipitation (RIP), and RNA pull-down assays were used to predict and validate the interaction between TFAP2A-AS1 and miR-933, as well as SMAD2 and miR-933. Western blot assay was performed to examine the protein expression of SMAD2 in treated BC cells. RESULTS TFAP2A-AS1 expression was significantly lower in BC tissues and cell lines, and patients with high TFAP2A-AS1 expression exhibited a better prognosis than those with low TFAP2A-AS1 expression. Overexpression of TFAP2A-AS1 in BC cells caused cell cycle arrest, promoted cell apoptosis, suppressed cell ability, and attenuated cell invasion in vitro, and inhibited tumor growth in vivo. TFAP2A-AS1 was revealed to act as a miRNA sponge for miR-933 and then regulated the expression of Smad2. CONCLUSIONS Results from the present study suggest that TFAP2A-AS1 acts as a tumor suppressor in BC via the miR-933/SMAD2 axis.