MAC30 knockdown involved in the activation of the Hippo signaling pathway in breast cancer cells

TMEM97 is transcriptionally activated by YY1 and promotes colorectal cancer progression via the GSK-3β/β-catenin signaling pathway

Transmembrane protein 97 (TMEM97) is a conserved integral membrane protein highly expressed in various human cancers, including colorectal cancer (CRC), and it exhibits pro-tumor roles in breast cancer, gastric cancer, and glioma. However, whether TMEM97 participates in CRC progression is not fully understood. The expression of mRNA and protein was evaluated by real-time qPCR, western blotting, immunofluorescent, and immunohistochemical staining. TMEM97 functions in cell proliferation, apoptosis, migration, and invasion were assessed by CCK-8, flow cytometry, and transwell assays. The roles of TMEM97 in CRC cells in vivo was investigated using a subcutaneous xenograft model. The transcriptional regulation of TMEM97 was explored by luciferase reporter and ChIP assays. The silencing of TMEM97 inhibited migration and invasion of CRC cells in vitro and led to suppressed growth and enhanced apoptosis in CRC cells and xenografts, whereas overexpression of TMEM97 displayed opposite effects. Mechanistically, TMEM97 knockdown caused a reduction of the proliferating marker PCNA and an increase of pro-apoptotic proteins (cleaved caspase 8/3/7 and cleaved PARP) in CRC cells. TMEM97 also positively regulated the β-catenin signaling pathway in CRC cells and xenografts by modulating the phosphorylated-GSK-3β and active (non-phospho) β-catenin levels. Interestingly, YY1, a well-recognized oncogenic transcription factor, was identified to bind to the TMEM97 promoter and enhance its transcriptional activity, and silencing of TMEM97 abolished YY1-mediated pro-tumor effects on CRC cells. Our results suggest that TMEM97 is transcriptionally activated by YY1 and promotes CRC progression via the GSK-3β/β-catenin signaling pathway, providing that TMEM97 might be a novel therapeutic target for preventing CRC development.

Transmembrane protein 97 exhibits oncogenic properties via enhancing LRP6-mediated Wnt signaling in breast cancer

Upregulation of transmembrane protein 97 (TMEM97) has been associated with progression and poor outcome in multiple human cancers, including breast cancer. Recent studies suggest that TMEM97 may be involved in the activation of the Wnt/β-catenin pathway. However, the molecular mechanism of TMEM97 action on Wnt/β-catenin signaling is completely unclear. In the current study, TMEM97 was identified as an LRP6-interacting protein. TMEM97 could interact with LRP6 intracellular domain and enhance LRP6-mediated Wnt signaling in a CK1δ/ε-dependent manner. The binding of TMEM97 to LRP6 facilitated the recruitment of CK1δ/ε to LRP6 complex, resulting in LRP6 phosphorylation at Ser 1490 and the stabilization of β-catenin. In breast cancer cells, knockout of TMEM97 attenuated the Wnt/β-catenin signaling cascade via regulating LRP6 phosphorylation, leading to a decrease in the expression of Wnt target genes AXIN2, LEF1, and survivin. TMEM97 deficiency also suppressed cell viability, proliferation, colony formation, migration, invasion, and stemness properties in breast cancer cells. Importantly, TMEM97 knockout suppressed tumor growth through downregulating the Wnt/β-catenin signaling pathway in a breast cancer xenograft model. Taken together, our results revealed that TMEM97 is a positive modulator of canonical Wnt signaling. TMEM97-mediated Wnt signaling is implicated in the tumorigenesis of breast cancer, and its targeted inhibition may be a promising therapeutic strategy for breast cancer.

Hippo/TEAD4 signaling pathway as a potential target for the treatment of breast cancer

Breast cancer is the most common type of cancer among women worldwide. The Hippo signaling pathway is strongly associated with cell proliferation, migration, invasion, metastasis and resistance to breast cancer treatment. The upstream factors involved in the Hippo signaling pathway, including mammalian Ste20 kinases 1/2, large tumor suppressor kinases 1/2 and transcription coactivator Yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ), have been extensively studied as they are considered therapeutic targets for breast cancer. Recently, it has been suggested that the transcriptional enhancer factor domain (TEAD) family of transcription factors, particularly TEAD4, plays an important role in breast cancer. TEADs interact with YAP/TAZ to act as transcription factors. Notably, recent studies have demonstrated that TEAD4 may also function in a YAP/TAZ-independent manner and serve as a prognostic marker for breast cancer. The present review summarizes the current research on the effect of the aberrant activation of the Hippo signaling pathway on breast cancer progression. Furthermore, the latest advances on the role of the TEAD family in breast cancer are highlighted, and the role of TEAD4 as a potential target for therapeutic intervention in breast cancer is discussed.

TMEM97 facilitates the activation of SOCE by downregulating the association of cholesterol to Orai1 in MDA-MB-231 cells

The expression of TMEM97, a regulator of cholesterol transport, has been reported to be enhanced in some tumour cells. We have recently shown that TMEM97 is involved in the proliferation of the breast cancer cell line MDA-MB-231, probably through changes in store-operated calcium entry (SOCE). By using silencing and overexpression of TMEM97 in MDA-MB-231 cells (two manoeuvres that either reduce or increase the calcium influx, respectively), we show enhanced cholesterol uptake in these cells as compared to the non-tumoral breast cell line, MCF10A. The enhanced cholesterol uptake in MDA-MB-231 cells was inhibited by silencing TMEM97, while overexpression of this protein increased cholesterol uptake in MCF10A cells and, therefore, indicating that this protein plays a role in the enhanced cholesterol uptake in MDA-MB-231 cancer cell line. TMEM97 silencing and overexpression resulted in an increase and decrease in the association of cholesterol to the SOCE calcium channel Orai1, respectively. Interestingly, silencing of TMEM97 in MDA-MB-231 cells significantly reduced the co-localization of Orai1 with the SOCE regulatory protein STIM1. Finally, neither silencing nor overexpression of TMEM97 altered SOCE in MDA-MB-231 cells transfected with the cholesterol insensible mutant of Orai1(Y80E). Our results reveal a novel regulatory mechanism of SOCE that relies on TMEM97 activity that courses through the reduction of the cholesterol content in the plasma membrane, and subsequently, by impairing its interaction with Orai1.

Meningioma-associated protein 30 accelerates the proliferation and invasion of hepatocellular carcinoma by modulating Wnt/GSK-3β/β-catenin signaling

Meningioma-associated protein 30 (MAC30) has been recently identified as a new tumor-associated protein that is implicated in multiple tumor types. However, the role of MAC30 in hepatocellular carcinoma (HCC) has not been studied. In the current study, we explored the expression, biological function and underlying mechanism of MAC30 in HCC. We found that MAC30 expression was significantly elevated in HCC tissues and cell lines. Functional in vitro assays demonstrated that the knockdown of MAC30 inhibited the proliferation and invasion of HCC cells, while MAC30 overexpression facilitated these biological behaviors. Moreover, the knockdown of MAC30 decreased glycogen synthase kinase (GSK)-3β phosphorylation level and β-catenin expression, leading to the inactivation of Wnt/β-catenin signaling in HCC cells. The inhibition of GSK-3β or reactivation Wnt/β-catenin signaling markedly reversed MAC30 knockdown-mediated inhibitory effects on the proliferation and invasion of HCC cells. Notably, the inhibition of Wnt/β-catenin signaling abrogated the MAC30-evoked oncogenic role in HCC cells. In addition, the knockdown of MAC30 impeded tumor formation and the growth rate of HCC cells in vivo. Taken together, our data recognized MAC30 as a potential tumor-promotion factor in HCC, which accelerated the proliferation and invasion of HCC through the up-regulation of Wnt/β-catenin signaling. Our study suggests MAC30 as a potential anticancer target for HCC.

New insights into the core Hippo signaling and biological macromolecules interactions in the biology of solid tumors

As an evolutionarily conserved pathway, Hippo signaling pathway impacts different pathology and physiology processes such as wound healing, tissue repair/size and regeneration. When some components of Hippo signaling dysregulated, it affects cancer cells proliferation. Moreover, the relation Hippo pathway with other signaling including Wnt, TGFβ, Notch, and EGFR signaling leaves effect on the proliferation of cancer cells. Utilizing a number of therapeutic approaches, such as siRNAs and long noncoding RNA (lncRNA) to prevent cancer cells through the targeting of Hippo pathways, can provide new insights into cancer target therapy. The purpose of present review, first of all, is to demonstrate the importance of Hippo signaling and its relation with other signaling pathways in cancer. It also tries to demonstrate targeting Hippo signaling progress in cancer therapy.

The Role of the Hippo Pathway in Breast Cancer Carcinogenesis, Prognosis, and Treatment: A Systematic Review

Background

The Hippo pathway is a developmental pathway recently discovered in Drosophila melanogaster; in mammals it normally controls organ development and wound healing. Hippo signaling is deregulated in breast cancer (BC). MST1/2 and LATS1/2 kinases are the upstream molecular elements of Hippo signaling which phosphorylate and regulate the two effectors of Hippo signaling, YAP1 and TAZ cotranscriptional activators. The two molecular effectors of the Hippo pathway facilitate their activity through TEAD transcription factors. Several molecular pathways with known oncogenic functions cross-talk with the Hippo pathway.

Methods

A systematic review studying the correlation of the Hippo pathway with BC tumorigenesis, prognosis, and treatment was performed.

Results

Recent literature highlights the critical role of Hippo signaling in a wide spectrum of biological mechanisms in BC.

Discussion

The Hippo pathway has a crucial position in BC molecular biology, cellular behavior, and response to treatment. Targeting the Hippo pathway could potentially improve the prognosis and outcome of BC patients.

LncRNA MALAT1/miR-181a-5p affects the proliferation and adhesion of myeloma cells via regulation of Hippo-YAP signaling pathway

Multiple myeloma (MM) is a plasma cells malignant proliferative disease, especially in aged people. LncRNAs have been considered as important regulators in MM. This research was to study the effect of LncRNA MALAT1 on the proliferation and adhesion of myeloma cells and whether Long non-coding RNAs MALAT1(LncRNA MALAT1) plays its regulative role through Hippo-YAP signaling pathway by targeting miR-181a-5p. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis was used to detect the LncRNA MALAT1/miR-181a-5p expression and improve the transfection efficiency. Western blot analysis was used to analyze the expression of proliferation and apoptosis related proteins and Hippo-Yes-associated protein (YAP) signaling pathway related proteins. Cell proliferative ability and cell apoptosis were respectively determined by Cell Counting Kit-8 (CCK-8) assay and flow cytometry analysis. ELISA assay was for the determination of adherence factors. Immunohistochemistry was to detect the expression of proliferation and adhesion related proteins. LncRNA MALAT1 targeting gene was determined by Dual-luciferase reporter assay. LncRNA MALAT1 was increased in MM cells and LncRNA MALAT1 interference could inhibit cell proliferation and promote cell apoptosis with the changes in the related proteins. Also, LncRNA MALAT1 interference could inhibit cell adhesion through Hippo-YAP signaling pathway. MiR-181a-5p was demonstrated to be a target of LncRNA MALAT1 and miR-181a-5p overexpression could also regulate the changes in cellular behavior in accordance with the LncRNA MALAT1 interference. In addition, LncRNA MALAT1 interference could decrease the expression of miR-181a-5p and inhibit the growth of tumor. In conclusion, this study showed that LncRNA MALAT1 interference inhibited the proliferation and adhesion of myeloma cells by the up-regulation of miR-181a-5p through activating the Hippo-YAP signaling pathway.

FRMPD1 activates the Hippo pathway via interaction with WWC3 to suppress the proliferation and invasiveness of lung cancer cells

Purpose: The expression of FERM-domain-containing protein-1 (FRMPD1)/FERM and PDZ domain-containing protein-2 (FRMD2) in malignant tumors, including lung cancer, and its underlying molecular mechanism have not been reported yet. Materials and methods: Immunohistochemistry was performed to analyze the expression of FRMPD1 in lung cancer tissues, and statistical analysis was applied to analyze the relationship between FRMPD1 expression and clinicopathological factors. The biological effects of FRMPD1 on lung cancer cell proliferation and invasion were determined by functional experiments both in vivo and in vitro. Immunoblotting, RT-qPCR, dual-luciferase assay, and immunofluorescence were performed to demonstrate whether FRMPD1 stimulates Hippo signaling. Co-immunoprecipitation assays were used to clarify the underlying role of FRMPD1 in Hippo pathway activation via interaction with WW and C2 domain containing protein-3 (WWC3). Results: We found that FRMPD1 expression in lung cancer specimens was lower than that in normal bronchial epithelium and normal submucosal glands. FRMPD1 expression had a negative correlation with age, Tumor-Node-Metastasis (TNM) stage, lymph node metastasis, as well as poor prognosis. Moreover, ectopic expression of FRMPD1 significantly inhibited the proliferation and invasion of lung cancer cells, and inhibition of FRMPD1 expression led to opposite effects. Mechanistically, we found that FRMPD1 interacted with the C-terminal PDZ binding motif of WWC3 via its PSD95/DLG/ZO1 (PDZ) domain and promoted the phosphorylation of large tumor suppressor-1 (LATS1), thus inhibiting the nuclear translocation of yes-associated protein (YAP). Conclusion: FRMPD1 could activate the Hippo pathway and ultimately inhibit the malignant behavior of lung cancer cells through its interaction with WWC3. This work will provide an important experimental basis for the discovery of novel biomarkers of lung cancer and the development of targeted drugs.