P44/WDR77 restricts the sensitivity of proliferating cells to TGFβ signaling

Exploring the mechanism of Scleromitrion diffusum (Willd.) in treating lung cancer based on network pharmacology and experimental validation

This study aims to elucidate the mechanisms by which the effective components of Scleromitrion diffusum (Willd.) (SDW) treat lung cancer, using network pharmacology, in vitro cell experiments, and molecular docking methods. Network pharmacology techniques were employed to construct a network of SDW components, lung cancer targets, and signaling pathways. A proteinprotein interaction (P P I) network was built for target genes, identifying core gene targets. Signaling pathway and biological process analyses were conducted. MT T assays measured cell viability, and Western blot analysis assessed the impact of core protein targets and key pathway proteins on the stemness of three lung cancer cell lines. Molecular docking was performed to link SDW components with core proteins and key pathway targets related to lung cancer. SDW was found to target 88 genes and 5 active components (2-methoxy-3-methyl-9-10-anthraquinone, stigmasterol, beta-sitosterol, quercetin, and poriferasterol) relevant to lung cancer treatment. The P I3K/Akt and MEK/ERK pathways were identified as major signaling pathways. Extracts from SDW roots significantly inhibited the proliferation of three lung cancer cell lines (A549, HCC827, and NCIH-1395), primarily via P I3K/Akt and MEK/ERK pathways, significantly reducing the expression of p-Akt and p-Erk1/2 and slightly inhibiting caspase-9, p-P I3K, and EGFR expression. Molecular docking confirmed the strong binding activities of SDW components with lung cancer-related core proteins and key pathway targets. SDW may regulate apoptosis and proliferation in lung cancer treatment through P I3K-Akt and MAP K/ERK signaling pathways. The combination of network pharmacology, molecular docking, and experimental validation provides valuable insights into the molecular mechanisms of SDW in lung cancer therapy.

HNRNPC promotes estrogen receptor-positive breast cancer cell cycle by stabilizing WDR77 mRNA in an m6A-dependent manner

Breast cancer has become the most commonly diagnosed cancer. Heterogeneous nuclear ribonucleoprotein C (HNRNPC), a reader of N6-methyladenosine (m6A), has been observed to be upregulated in various types of cancer. Nevertheless, the role of HNRNPC in breast cancer and whether it is regulated by m6A modification deserve further investigation. The expression of HNRNPC in breast cancer was examined by quantitative real-time polymerase chain reaction and western blot analysis. RNA immunoprecipitation was performed to validate the binding relationships between HNRNPC and WD repeat domain 77 (WDR77). The effects of HNRNPC and m6A regulators on WDR77 were investigated by actinomycin D assay. The experiments in vivo were conducted in xenograft models. In this research, we found that HNRNPC was highly expressed in breast cancer, and played a crucial role in cell growth, especially in the luminal subtype. HNRNPC could combine and stabilize WDR77 mRNA. WDR77 successively drove the G1/S phase transition in the cell cycle and promoted cell proliferation. Notably, this regulation axis was closely tied to the m6A modification status of WDR77 mRNA. Overall, a critical regulatory mechanism was identified, as well as promising targets for potential treatment strategies for luminal breast cancer.

The essential role of WD repeat domain 77 in prostate tumor initiation induced by Pten loss

Prostate cancer is the most commonly diagnosed malignancy among men, but few genetic factors that drive prostate cancer initiation have been identified. The WD repeat domain 77 (Wdr77) protein is essential for cellular proliferation when localizes in the cytoplasm of epithelial cells at the early stage of prostate development. In the adult prostate, it is transported into the nucleus and functions as a co-regulator of the androgen receptor to promote cellular differentiation and prostate function. This developmental process is reversed during prostate tumorigenesis, i.e., Wdr77 is translocated from the nucleus into the cytoplasm to drive proliferation of prostate cancer cells. In this study, we used in vivo genetic studies to further investigate the role of Wdr77 in prostate tumorigenesis. We found that prostate-specific deletion of Wdr77 abolished prostate tumor initiation induced by loss of the tumor suppressor Pten. Mechanistically, Wdr77 ablation inhibited E2F3 activation and enhanced TGFβ signaling, leading to attenuated cellular proliferation induced by loss of Pten. These findings establish a critical role of Wdr77 for prostate tumor initiation.

The PRMT5/WDR77 complex regulates alternative splicing through ZNF326 in breast cancer

We observed overexpression and increased intra-nuclear accumulation of the PRMT5/WDR77 in breast cancer cell lines relative to immortalized breast epithelial cells. Utilizing mass spectrometry and biochemistry approaches we identified the Zn-finger protein ZNF326, as a novel interaction partner and substrate of the nuclear PRMT5/WDR77 complex. ZNF326 is symmetrically dimethylated at arginine 175 (R175) and this modification is lost in a PRMT5 and WDR77-dependent manner. Loss of PRMT5 or WDR77 in MDA-MB-231 cells leads to defects in alternative splicing, including inclusion of A-T rich exons in target genes, a phenomenon that has previously been observed upon loss of ZNF326. We observed that the alternatively spliced transcripts of a subset of these genes, involved in proliferation and tumor cell migration like REPIN1/AP4, ST3GAL6, TRNAU1AP and PFKM are degraded upon loss of PRMT5. In summary, we have identified a novel mechanism through which the PRMT5/WDR77 complex maintains the balance between splicing and mRNA stability through methylation of ZNF326.

The Structure and Function of the PRMT5:MEP50 Complex

Protein arginine methyltransferase 5 (PRMT5) plays multiple roles in cellular processes at different stages of the cell cycle in a tissue specific manner. PRMT5 in complex with MEP50/p44/WDR77 associates with a plethora of partner proteins to symmetrically dimethylate arginine residues on target proteins in both the nucleus and the cytoplasm. Overexpression of PRMT5 has been observed in several cancers, making it an attractive drug target. The structure of the 453 kDa heterooctameric PRMT5:MEP50 complex bound to an S-adenosylmethionine analog and a substrate peptide provides valuable insights into this intriguing target.

Protein arginine methyltransferase 5 regulates multiple signaling pathways to promote lung cancer cell proliferation

BACKGROUND

Protein arginine methyltransferase 5 (PRMT5) catalyzes the formation of symmetrical dimethylation of arginine residues in proteins. WD repeat domain 77 (WDR77), also known as p44, MEP50, or WD45, forms a stoichiometric complex with PRMT5. The PRMT5/p44 complex is required for cellular proliferation of lung and prostate epithelial cells during earlier stages of development and is re-activated during prostate and lung tumorigenesis. The molecular mechanisms by which PRMT5 and p44 promote cellular proliferation are unknown.

METHODS

Expression of PRMT5 and p44 in lung and prostate cancer cells was silenced and their target genes were identified. The regulation of target genes was validated in various cancer cells during lung development and tumorigenesis. Altered expression of target genes was achieved by ectopic cDNA expression and shRNA-mediated silencing.

RESULTS

PRMT5 and p44 regulate expression of a specific set of genes encoding growth and anti-growth factors, including receptor tyrosine kinases and antiproliferative proteins. Genes whose expression was suppressed by PRMT5 and p44 encoded anti-growth factors and inhibited cell growth when ectopically expressed. In contrast, genes whose expression was enhanced by PRMT5 and p44 encoded growth factors and increased cell growth when expressed. Altered expression of target genes is associated with re-activation of PRMT5 and p44 during lung tumorigenesis.

CONCLUSIONS

Our data provide the molecular basis by which PRMT5 and p44 regulate cell growth and lay a foundation for further investigation of their role in lung tumor initiation.

Yeast two-hybrid screening identified WDR77 as a novel interacting partner of TSC22D2

Transforming growth factor β-stimulated clone 22 domain family, member 2 (TSC22D2), a member of the TSC22D family, has been implicated as a tumor-associated gene, but its function remains unknown. To further explore its biological role, yeast two-hybrid screening combined with multiple bioinformatics tools was used to identify 44 potential interacting partners of the TSC22D2 protein that were mainly involved in gene transcription, cellular metabolism, and cell cycle regulation. The protein WD repeat domain 77 (WDR77) was selected for further validation due to its function in the cell cycle and tumor development, as well as its high detection frequency in the yeast two-hybrid assay. Immunoprecipitation and immunofluorescence experiments confirmed an interaction between the TSC22D2 and WDR77 proteins. Our work greatly expands the putative protein interaction network of TSC22D2 and provides deeper insight into the biological functions of the TSC22D2 and WDR77 proteins.

GLI pathogenesis-related 1 functions as a tumor-suppressor in lung cancer

Background

GLI pathogenesis-related 1 (GLIPR1) was originally identified in glioblastomas and its expression was also found to be down-regulated in prostate cancer. Functional studies revealed both growth suppression and proapoptotic activities for GLIPR1 in multiple cancer cell lines. GLIPR1’s role in lung cancer has not been investigated. Protein arginine methyltransferase 5 (PRMT5) is a protein arginine methyltransferase and forms a stoichiometric complex with the WD repeat domain 77 (WDR77) protein. Both PRMT5 and WDR77 are essential for growth of lung epithelial and cancer cells. But additional gene products that interact genetically or biochemichally with PRMT5 and WDR77 in the control of lung cancer cell growth are not characterized.

Methods

DNA microarray and immunostaining were used to detect GLIPR1 expression during lung development and lung tumorigenesis. GLIPR1 expression was also analyzed in the TCGA lung cancer cohort. The consequence of GLIPR1 on growth of lung cancer cells in the tissue culture and lung tumor xenografts in the nude mice was observed.

Results

We found that GLIPR1 expression is negatively associated with PRMT5/WDR77. GLIPR1 is absent in growing epithelial cells at the early stages of mouse lung development and highly expressed in the adult lung. Expression of GLIPR1 was down-regulated during lung tumorigenesis and its expression suppressed growth of lung cancer cells in the tissue culture and lung tumor xenografts in mice. GLIPR1 regulates lung cancer growth through the V-Erb-B avian erythroblastic leukemia viral oncogene homolog 3 (ErbB3).

Conclusions

This study reveals a novel pathway that PRMT5/WDR77 regulates GLIPR1 expression to control lung cancer cell growth and GLIPR1 as a potential therapeutic agent for lung cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-016-0508-4) contains supplementary material, which is available to authorized users.

The Wnt11 Signaling Pathway in Potential Cellular EMT and Osteochondral Differentiation Progression in Nephrolithiasis Formation

The molecular events leading to nephrolithiasis are extremely complex. Previous studies demonstrated that calcium and transforming growth factor-β1 (TGF-β1) may participate in the pathogenesis of stone formation, but the explicit mechanism has not been defined. Using a self-created genetic hypercalciuric stone-forming (GHS) rat model, we observed that the increased level of serous/uric TGF-β1 and elevated intracellular calcium in primary renal tubular epithelial cells (PRECs) was associated with nephrolithiasis progression in vivo. In the setting of high calcium plus high TGF-β1 in vitro, PRECs showed great potential epithelial to mesenchymal transition (EMT) progression and osteochondral differentiation properties, representing the multifarious increased mesenchymal and osteochondral phenotypes (Zeb1, Snail1, Col2A1, OPN, Sox9, Runx2) and decreased epithelial phenotypes (E-cadherin, CK19) bythe detection of mRNAs and corresponding proteins. Moreover, TGF-β-dependent Wnt11 knockdown and L-type Ca²⁺ channel blocker could greatly reverse EMT progression and osteochondral differentiation in PRECs. TGF-β1 alone could effectively promote EMT, but it had no effect on osteochondral differentiation in NRK cells (Rat kidney epithelial cell line). Stimulation with Ca²⁺ alone did not accelerate differentiation of NRK. Co-incubation of extracellular Ca²⁺ and TGF-β1 synergistically promotes EMT and osteochondral differentiation in NRK control cells. Our data supplied a novel view that the pathogenesis of calcium stone development may be associated with synergic effects of TGF-β1 and Ca²⁺, which promote EMT and osteochondral differentiation via Wnt11 and the L-type calcium channel.