PLCA8 suppresses breast cancer apoptosis by activating the PI3k/AKT/NF-κB pathway

PLAC8 attenuates pulmonary fibrosis and inhibits apoptosis of alveolar epithelial cells via facilitating autophagy

Idiopathic pulmonary fibrosis (IPF) is an irreversible lung condition that progresses over time, which ultimately results in respiratory failure and mortality. In this study, we found that PLAC8 was downregulated in the lungs of IPF patients based on GEO data, in bleomycin (BLM)-induced lungs of mice, and in primary murine alveolar epithelial type II (pmATII) cells and human lung epithelial cell A549 cells. Overexpression of PLAC8 facilitated autophagy and inhibited apoptosis of pmATII cells and A549 cells in vitro. Moreover, inhibition of autophagy or overexpression of p53 partially abolished the effects of PLAC8 on cell apoptosis. ATII cell-specific overexpression of PLAC8 alleviated BLM-induced pulmonary fibrosis in mice. Mechanistically, PLAC8 interacts with VCP-UFD1-NPLOC4 complex to promote p53 degradation and facilitate autophagy, resulting in inhibiting apoptosis of alveolar epithelial cells and attenuating pulmonary fibrosis. In summary, these findings indicate that PLAC8 may be a key target for therapeutic interventions in pulmonary fibrosis.

Machine learning-derived natural killer cell signature predicts prognosis and therapeutic response in clear cell renal cell carcinoma

BACKGROUND

Natural killer cells, interconnected with patient prognosis and treatment response, play a pivotal role in the tumor immune microenvironment and may serve as potential novel predictive biomarkers for renal cell carcinoma.

METHODS

Clear cell renal cell carcinoma transcriptome data and the corresponding clinical data were obtained from the Cancer Genome Atlas (TCGA) database. Single-cell sequencing data were sourced from the Gene Expression Omnibus (GEO) database. A risk model was established by integrating ten different machine learning algorithms, which resulted in 101 combined models. The model with the highest average C-index was selected for further analysis, and was assessed using nomogram, time-dependent receiver operating characteristics (ROC) and Kaplan-Meier survival analysis. The differences in immune infiltration fractions, clinicopathological features, and response to various targeted therapies and immunotherapy between high- and low-risk groups were investigated. Furthermore, qRT-PCR, IHC, colony formation test, CCK8 assay and flow cytometry were conducted to explore the expression pattern and function of ARHGAP9 in our own patient samples and renal cancer cell lines.

RESULTS

Totally, 156 NK cell-related genes and 5189 prognosis-related genes were identified, and 36 genes of their intersection demonstrated prognostic value. A risk model with 18 genes was established by Coxboost plus plsRcox, which can accurately predict the prognosis of ccRCC patients. Significant correlations were determined between risk score and tumor malignancy and immune cell infiltration. Meanwhile, a combination of tumor mutation burden plus risk score could have higher accuracy of predicting clinical outcomes. Moreover, high-risk group patients were more likely to be responsive to targeted therapy but show no response to immunotherapy.

CONCLUSIONS

Intricate signaling interactions between NK cells and various cellular subgroups were depicted and the developmental trajectory of NK cells was elucidated. A NK cells-related risk model was established, which can provide reliable prognostic information and identified patients with more probability of benefiting from therapy.

Role of UFMylation in tumorigenesis and cancer immunotherapy

Protein post-translational modifications (PTMs) represent a crucial aspect of cellular regulation, occurring after protein synthesis from mRNA. These modifications, which include phosphorylation, ubiquitination, acetylation, methylation, glycosylation, Sumoylation, and palmitoylation, play pivotal roles in modulating protein function. PTMs influence protein localization, stability, and interactions, thereby orchestrating a variety of cellular processes in response to internal and external stimuli. Dysregulation of PTMs is linked to a spectrum of diseases, such as cancer, inflammatory diseases, and neurodegenerative disorders. UFMylation, a type of PTMs, has recently gained prominence for its regulatory role in numerous cellular processes, including protein stability, response to cellular stress, and key signaling pathways influencing cellular functions. This review highlights the crucial function of UFMylation in the development and progression of tumors, underscoring its potential as a therapeutic target. Moreover, we discuss the pivotal role of UFMylation in tumorigenesis and malignant progression, and explore its impact on cancer immunotherapy. The article aims to provide a comprehensive overview of biological functions of UFMylation and propose how targeting UFMylation could enhance the effectiveness of cancer immunotherapy strategies.

Modulation of the tumor microenvironment and mechanism of immunotherapy-based drug resistance in breast cancer

Breast cancer, the most frequent female malignancy, is often curable when detected at an early stage. The treatment of metastatic breast cancer is more challenging and may be unresponsive to conventional therapy. Immunotherapy is crucial for treating metastatic breast cancer, but its resistance is a major limitation. The tumor microenvironment (TME) is vital in modulating the immunotherapy response. Various tumor microenvironmental components, such as cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), and myeloid-derived suppressor cells (MDSCs), are involved in TME modulation to cause immunotherapy resistance. This review highlights the role of stromal cells in modulating the breast tumor microenvironment, including the involvement of CAF-TAM interaction, alteration of tumor metabolism leading to immunotherapy failure, and other latest strategies, including high throughput genomic screening, single-cell and spatial omics techniques for identifying tumor immune genes regulating immunotherapy response. This review emphasizes the therapeutic approach to overcome breast cancer immune resistance through CAF reprogramming, modulation of TAM polarization, tumor metabolism, and genomic alterations.

microRNA-944 inhibits breast cancer cell proliferation and promotes cell apoptosis by reducing SPP1 through inactivating the PI3K/Akt pathway

Breast cancer is a common malignancy in women with poor prognosis. This study aimed to investigate the molecular mechanism of microRNA-944 (miR-944) mediated secreted phosphoprotein-1 (SPP1) in breast cancer progression and its regulatory effect on the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. Differential gene analysis was performed to identify key genes associated with breast cancer development by screening breast cancer-related microarray data. The expression of miR-944 and SPP1 and their relationship were determined in clinical samples and cells. sh-SPP1, oe-SPP1, LY294002 or miR-944 mimic were transfected into MCF-7 cells to investigate the role of miR-944 mediated SPP1 in breast cancer development and its regulatory effect on the PI3K/Akt pathway. Finally, the tumorigenicity of breast cancer cells was observed in nude mice. Through bioinformatics analysis, we identified SPP1 as a key gene in breast cancer, and miR-944 as an upstream miRNA of SPP1. In breast cancer tissues and cells, the expression of miR-944 was decreased while that of SPP1 was increased. miR-944 negatively regulated the expression of SPP1. In breast cancer cells, SPP1 activated the PI3K/Akt pathway to promote cell proliferation and inhibit apoptosis. In vitro cell experiments showed that the downregulation of miR-944 promoted the high expression of SPP1, which then activated the PI3K/Akt signaling pathway, promoting breast cancer cell proliferation. In vivo experiments further confirmed the anti-cancer role of miR-944 mediated SPP1 in breast cancer. Our study highlights the role of miR-944 mediated SPP1 in inhibiting breast cancer progression by blocking the PI3K/Akt pathway.

PLAC8 contributes to the malignant behaviors of cervical cancer cells by activating the SOX4-mediated AKT pathway

Cervical cancer (CC) is the primary cancer-related cause of morbidity and mortality in women. Previous studies have shown that placenta-specific 8 (PLAC8) has different functions in multiple malignancies. This study aimed to explore the function and regulatory mechanism of PLAC8 in CC. Bioinformatics and immunohistochemical analyses demonstrated that PLAC8 was significantly upregulated in CC tissues compared with normal tissues. Gain/loss-of-function experiments showed that siRNA-mediated knockdown of PLAC8 suppressed cell migration and invasion, while PLAC8 overexpression promoted cell motility. Moreover, PLAC8 was revealed to affect the epithelial-mesenchymal transition (EMT) process by upregulating epithelial (E)-cadherin and decreasing the expression of mesenchymal markers of EMT, including vimentin, zinc finger E-box binding homeobox 1 (ZEB1), neural (N)-cadherin, matrix metalloproteinase-9 (MMP-9), and MMP-2 in PLAC8-silenced cells. PLAC8 activated the AKT pathway, as proven by the downregulation of p-AKT_Ser473 and p-AKT_Thr308 expression after PLAC8 knockdown. Furthermore, PLAC8 overexpression upregulated the expression of sex-determining region Y-related high-mobility group box transcription factor 4 (SOX4), which is reported to mediate the activation of the AKT pathway, and SOX4 deficiency reversed the cellular functions caused by PLAC8 overexpression. Overall, the present study indicates that PLAC8 may facilitate CC development by activating the SOX4-mediated AKT pathway, suggesting that PLAC8 may serve as a potential biomarker for CC treatment.

Recent advances of bioactive proteins/polypeptides in the treatment of breast cancer

Proteins do not only serve as nutrients to fulfill the demand for food, but also are used as a source of bioactive proteins/polypeptides for regulating physical functions and promoting physical health. Female breast cancer has the highest incidence in the world and is a serious threat to women's health. Bioactive proteins/polypeptides exert strong anti-tumor effects and exhibit inhibition of multiple breast cancer cells. This review discussed the suppressing effects of bioactive proteins/polypeptides on breast cancer in vitro and in vivo, and their mechanisms of migration and invasion inhibition, apoptosis induction, and cell cycle arrest. This may contribute to providing a basis for the development of bioactive proteins/polypeptides for the treatment of breast cancer.

Graphical abstract

Extracellular vesicles derived from cancer-associated fibroblasts carry tumor-promotive microRNA-1228-3p to enhance the resistance of hepatocellular carcinoma cells to sorafenib

Cancer-associated fibroblasts (CAFs)-derived extracellular vesicles (EVs) can promote tumor progression by delivering microRNA (miRNA). Whether EVs could transfer miR-1228-3p into hepatocellular carcinoma (HCC) cells to affect chemoresistance was discussed in this study. Normal fibroblasts (NFs) and CAFs were isolated from tissue samples of HCC patients. We assessed the functions of HCC cells after co-culturing with NFs and CAFs. miR-1228-3p gain-of-function experiments were conducted. Next, functional assays were carried out to determine the binding of miR-1228-3p to placenta associated 8 (PLAC8). In vivo models were constructed for validation. CAFs-derived EVs exerted promoting effect on proliferative, migrating, invading potential of HCC cells and their resistance to sorafenib. PLAC8 was demonstrated as a direct target of miR-1228-3p. By targeting PLAC8, miR-1228-3p activated the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway. In addition, the transfer of miR-1228-3p from CAFs-derived EVs into HCC cells boosted chemoresistance of HCC cells, which was reversed by restoring PLAC8. All in all, CAF-EV-carried miR-1228-3p strengthens the chemoresistance of HCC through activating PLAC8-mediated PI3K/AKT pathway. This finding contributes to the development of EV-based therapies overcoming the chemoresistance of HCC.

Modification of PLAC8 by UFM1 affects tumorous proliferation and immune response by impacting PD-L1 levels in triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer is characterized by a poor prognosis and lack of targeted treatments, and thus, new targeting markers and therapeutic strategies are urgently needed. We previously indicated that PLAC8 promotes tumorigenesis and exerts multidrug resistance in breast cancer. Therefore, we aimed to characterize the PLAC8-regulated network in triple-negative breast cancer.

METHODS

We measured the levels of PLAC8 in breast cancer cell lines and found that PLAC8 is post-translationally modified by ubiquitin-fold modifier 1 (UFM1). Then, we revealed a new regulatory system of PD-L1 by PLAC8 in triple-negative breast cancer. We also tested the molecular functions of PLAC8 in triple-negative breast cancer cell lines and measured the expression of PLAC8 and PD-L1 in breast cancer tissues.

RESULTS

PLAC8 was generally highly expressed in triple-negative breast cancer and could be modified by UFM1, which maintains PLAC8 protein stability. Moreover, PLAC8 could promote cancer cell proliferation and affect the immune response by regulating the level of PD-L1 ubiquitination. Additionally, among patients with breast cancer, the expression of PLAC8 was higher in triple-negative breast cancer than in non-triple-negative breast cancer and positively correlated with the level of PD-L1.

CONCLUSIONS

Our current study discoveries a new PLAC8-regulated network in triple-negative breast cancer and provides corresponding guidance for the clinical diagnosis and immunotherapy of triple-negative breast cancer.

Ginsenoside CK, rather than Rb1, possesses potential chemopreventive activities in human gastric cancer via regulating PI3K/AKT/NF-κB signal pathway

Ginsenoside Rb1, a main component of ginseng, is often transformed into ginsenoside CK by intestinal flora to exert various pharmacological activity. However, it remains unclear whether ginsenoside CK is responsible for the anti-gastric cancer effect of ginsenoside Rb1 in vivo. In this study, network pharmacology was applied to predict the key signal pathways of ginsenoside Rb1 and ginsenoside CK when treating gastric cancer. The anti-proliferative effects of ginsenoside Rb1 and ginsenoside CK and the underlying mechanism in gastric cancer cells were explored by MTT, Hoechst3328 staining, ELISA, RT-qPCR and Western blotting. The results showed that PI3K-AKT/NF-κB signal pathway was the common important pathway of ginsenoside Rb1 and CK in the treatment of gastric cancer. The results of MTT assay showed that ginsenoside Rb1 could hardly inhibit the proliferation of HGC-27 cells, whereas ginsenoside CK could inhibit the proliferation of HGC-27 cells. Hoechst3328 staining showed that cells in the ginsenoside CK group were densely stained bright blue and nuclear fragmented, indicating that apoptosis occurred. ELISA results showed that ginsenoside CK could effectively downregulate the levels of cyclin CyclinB1 and CyclinD1, but ginsenoside Rb1 had no significant effect. Also, the results of Western blot and RT-qPCR showed that ginsenoside CK inhibited the expressions of anti-apoptosis-related protein Bcl-2 and apoptosis-related pathway PI3K/AKT/NF-κB, and promoted the expression of pro-apoptosis proteins Bax and Caspase 3, whereas ginsenoside Rb1 exerted no effect. In short, ginsenoside Rb1 had no anti-gastric cancer cell activity in vitro, but ginsenoside CK could effectively inhibit cell proliferation and induce cell apoptosis in HGC-27 cells. The mechanism might relate to the inhibitory effect of ginsenoside CK on the PI3K/AKT/NF-κB pathway. These results suggest that ginsenoside CK might be the in vivo material basis for the anti-gastric cancer activity of ginsenosides.

Prediction of the mechanism of Dachengqi Decoction treating colorectal cancer based on the analysis method of " into serum components -action target-key pathway"

ETHNOPHARMACOLOGICAL RELEVANCE

Colorectal cancer (CRC) is a common digestive tract malignant tumor that its morbidity and mortality seriously affect human health. At present, Dachengqi Decoction (DCQ), a traditional Chinese medicine formula, has been clinically used as an adjuvant therapy for CRC. However, pharmacodynamic substance basis and therapeutic mechanism are still unclear.

AIM OF THE STUDY

The main constituents absorbed in the blood and possible active targets after DCQ administration were explored based on the analysis method of "into serum components, action target and key pathway", which may provide reference for the study of the pharmacodynamic material basis and action mechanism of Dachengqi Decoction in the treatment of CRC.

MATERIAL AND METHODS

Based on the serum pharmacochemistry of traditional Chinese medicine (TCM), the prescription prototype ingredients of DCQ in mice serum samples were identified by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry technology (UPLC-Q-TOF-MS^E). Taking the prototype ingredients absorbed into serum as the research object, the possible targets and key pathways of DCQ in vivo were demonstrated by network pharmacology. Finally, using molecular docking verified the binding activity of prototype components and potential action targets.

RESULTS

A total of 46 prototype components of DCQ were identified in mice serum, most of which were derived from flavonoids and anthraquinones in Citrus aurantium L. and Rheum palmatum L. Network pharmacology prediction results indicated that the drug prototype components entering the serum may mainly regulate targets including mitogen-activated protein kinase (MAPK), interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), etc. and main pathways such as (phosphatidylinositol 3-kinase/protein kinase B) PI3K-AKT signaling pathway, advanced glycation end products-receptor for AGE (AGE-RAGE) signaling pathway and IL-17 signaling pathway, etc. Molecular docking showed that the prototype active components had strong binding activity to VEGF, Harvey rat sarcoma viral oncogene homolog (HRAS) and MAPK1.

CONCLUSIONS

This study elucidated that most of the direct acting substances of DCQ in vivo were flavonoids and anthraquinones, which may play a role in regulating cell reproduction and apoptosis and inhibiting inflammation, providing a reference for the research of pharmacodynamic material basis and mechanism of DCQ in the treatment of CRC.

The biology of YAP in programmed cell death

In the last few decades, YAP has been shown to be critical in regulating tumor progression. YAP activity can be regulated by many kinase cascade pathways and proteins through phosphorylation and promotion of cytoplasmic localization. Other factors can also affect YAP activity by modulating its binding to different transcription factors (TFs). Programmed cell death (PCD) is a genetically controlled suicide process present with the scope of eliminating cells unnecessary or detrimental for the proper development of the organism. In some specific states, PCD is activated and facilitates the selective elimination of certain types of tumor cells. As a candidate oncogene correlates with many regulatory factors, YAP can inhibit or induce different forms of PCD, including apoptosis, autophagy, ferroptosis and pyroptosis. Furthermore, YAP may act as a bridge between different forms of PCD, eventually leading to different outcomes regarding tumor development. Researches on YAP and PCD may benefit the future development of novel treatment strategies for some diseases. Therefore, in this review, we provide a general overview of the cellular functions of YAP and the relationship between YAP and PCD.

HJURP regulates cell proliferation and chemo-resistance via YAP1/NDRG1 transcriptional axis in triple-negative breast cancer

Triple-negative breast cancer is still a difficult point in clinical treatment at present, and a deep study of its pathogenesis has great clinical value. Therefore, our research mainly focuses on exploring the progression of triple-negative breast cancer and determines the important role of the HJURP/YAP1/NDRG1 transcriptional regulation axis in triple-negative breast cancer. We observed significantly increased HJURP expression levels in triple-negative breast cancer compared to other subtypes. HJURP could affect the level of ubiquitination modification of YAP1 protein and then regulate its downstream transcriptional activity. Mechanistically, we found that YAP1 positively regulates NDRG1 transcription by binding the promoter region of the NDRG1 gene. And HJURP/YAP1/NDRG1 axis could affect cell proliferation and chemotherapy sensitivity in triple-negative breast cancer. Taken together, these findings provide insights into the transcriptional regulation axis of HJURP/YAP1/NDRG1 in triple-negative breast cancer progression and therapeutic response.

Clinical study on Yanghe decoction in improving neo-adjuvant chemotherapy efficacy and immune function of breast cancer patients

INTRODUCTION

Neoadjuvant chemotherapy (NAC) plays an important role in downgrading preoperative tumor size, providing information on regimen activity, and increases treatment efficacy in breast cancer patients. An increasing number of patients have sought Traditional Chinese Medicine (TCM) during NAC to relieve discomfort, regulate immune function, and improve survival. However, limited evidence is available on how concurrent TCM treatment combined with NAC affects tumor response. This study aims to assess the efficacy of Yanghe decoction, a classical warming Yang formula, on pathological complete response (pCR) and explore its mechanism via the phosphatidylinositol-3-kinase/ protein kinase B/nuclear factor kappa-B (PI3K/Akt/NF-κB) pathway-mediated immune-inflammation microenvironment.

METHODS

A single-center, randomized, placebo-controlled, double-blinded randomized control trial (RCT) was designed. This trial aims to recruit 128 participants with breast cancer scheduled to receive NAC in China. All participants will be randomly assigned (1:1) to the Neo-Yanghe group (Yanghe decoction plus NAC) or the control group (placebo plus NAC). The primary outcome will be evaluated by the proportion of participants achieving pCR. The secondary outcomes include the expression level of PI3K/Akt/NF-κB pathway-related proteins, the objective response rate, the time to response, serum level of immune-inflammatory indicators, quality of life, disease-free survival, and overall survival.

DISCUSSION

This study will be the first RCT to evaluate the efficacy of Yanghe decoction combined with NAC in treating breast cancer patients, and elucidate the antitumor mechanism via the PI3K/Akt/NF-κB pathway-mediated immune-inflammation microenvironment. If possible, Neo-Yanghe treatment pattern will be a better pharmacological intervention to manage breast cancer than chemotherapy alone. The results of the trial will provide research-based evidence for the development of integrated Chinese and Western medicine guidelines and expert consensus.Trial registration: Chinese Clinical Trial Registry ChiCTR-INR-2000036943. Registered on September 28, 2020 (https://www.chictr.org.cn/hvshowproject.aspx?id=57141).

Long noncoding RNA HOXD-AS1 promotes the progression of pancreatic cancer through miR-664b-3p/PLAC8 axis

Pancreatic cancer (PC) is one of the most common malignancies worldwide. There are no effective early diagnosis and therapeutic methods for PC. Mounting evidence has shown that lncRNAs promote PC progression. For instance, HOXD-AS1 acts as an oncogenic lncRNA in some digestive tumors. However, its role in PC is unknown. This study aimed to investigate the role of HOXD-AS1 in PC and its underlying mechanisms. Quantitative reverse transcription (qRT‑PCR) was used to measure the expression levels of HOXD-AS1, miR-664b-3p, and PLAC8. CCK-8, colony formation, wound healing, and transwell assays were used to assess the effect of HOXD-AS1 on the proliferation, invasion and migration of PC cells. Dual-luciferase reporter and cell function rescue assays were used to verify the regulation relationship of miR-664b-3p and HOXD-AS1 or PLAC8. HOXD-AS1 was significantly upregulated in PC tissues than in paired adjacent tissues. Moreover, HOXD-AS1 was related to the advanced TNM stage. Meanwhile, HOXD-AS1 promoted the proliferation, invasion, and migration of PC cells. Mechanically, HOXD-AS1 upregulated PLAC8 by targeting miR-664b-3p. In conclusion, HOXD-AS1 was upregulated in PC tissues, promoting the proliferation, invasion, and migration of PC cells via the miR-664b-3p/PLAC8 axis.

miR-22 and miR-205 Drive Tumor Aggressiveness of Mucoepidermoid Carcinomas of Salivary Glands

Objectives

To integrate mRNA and miRNA expression profiles of mucoepidermoid carcinomas (MECs) and normal salivary gland (NSGs) tissue samples and identify potential drivers.

Material and Methods

Gene and miRNA expression arrays were performed in 35 MECs and six NSGs.

Results

We found 46 differentially expressed (DE) miRNAs and 3,162 DE mRNAs. Supervised hierarchical clustering analysis of the DE transcripts revealed two clusters in both miRNA and mRNA profiles, which distinguished MEC from NSG samples. The integrative miRNA-mRNA analysis revealed a network comprising 696 negatively correlated interactions (44 miRNAs and 444 mRNAs) involving cell signaling, cell cycle, and cancer-related pathways. Increased expression levels of miR-205-5p and miR-224-5p and decreased expression levels of miR-139-3p, miR-145-3p, miR-148a-3p, miR-186-5p, miR-338-3p, miR-363-3p, and miR-4324 were significantly related to worse overall survival in MEC patients. Two overexpressed miRNAs in MEC (miR-22 and miR-205) were selected for inhibition by the CRISPR-Cas9 method. Cell viability, migration, and invasion assays were performed using an intermediate grade MEC cell line. Knockout of miR-205 reduced cell viability and enhanced ZEB2 expression, while miR-22 knockout reduced cell migration and invasion and enhanced ESR1 expression. Our results indicate a distinct transcriptomic profile of MEC compared to NSG, and the integrative analysis highlighted miRNA-mRNA interactions involving cancer-related pathways, including PTEN and PI3K/AKT.

Conclusion

The in vitro functional studies revealed that miR-22 and miR-205 deficiencies reduced the viability, migration, and invasion of the MEC cells suggesting they are potential oncogenic drivers in MEC.

Loss of plac8 expression rapidly leads pluripotent stem cells to enter active state during planarian regeneration

The regenerative ability of planarians relies on their adult pluripotent stem cell population. Although all stem cells express a piwi homolog, recently it has become possible to classify the piwi+ stem cell population into specialized subpopulations according to the expression of genes related to differentiation. However, piwi+ stem cells behave practically as a homogeneous population after amputation, during which stem cells show accelerated proliferation, named ‘induced hyperproliferation’. Here, we show that plac8-A was expressed in almost all of the stem cells, and that a decrease of the plac8-A expression level led to induced hyperproliferation uniformly in a broad stem cell subpopulation after amputation. This reduction of plac8-A expression was caused by activated JNK signaling after amputation. Pharmacological inhibition of JNK signaling caused failure to induce hyperproliferation and resulted in regenerative defects. Such defects were abrogated by simultaneous knockdown of plac8-A expression. Thus, JNK-dependent suppression of plac8-A expression is indispensable for stem cell dynamics involved in regeneration. These findings suggest that plac8-A acts as a molecular switch of piwi+ stem cells for entry into the regenerative state after amputation.

Placenta-specific 8 (PLAC8) mediates inflammation and mobility of the hPDLCs via MEK/ERK signaling pathway

BACKGROUND

Placenta-specific 8 (PLAC8) is reported to regulate cellular functions in the progression of various diseases. However, its role in periodontitis is still unclear.

METHODS

Human periodontal ligament cells (hPDLCs) were treated with lipopolysaccharide of Porphyromonas Gingivalis (LPS-PG) to mimic periodontitis in vitro. Real-time quantitative polymerase chain reaction (RT-qPCR) was performed to measure the mRNA expression levels and western blot was for protein levels. Wound healing and transwell migration assays were performed to assess the cell mobility of hPDLCs. Both mRNA and protein levels of inflammatory cytokines including IFN-γ, IL-17, TNF-α, IL-4, IL-10 and IL-13 were accessed to evaluated process of periodontitis in vitro. Furthermore, the protein expressions of mitogen-activated protein kinase kinase (MEK), extracellular regulated protein kinase (ERK) and their phosphorylated products quantified by western blotting assay were determined to confirm the activation of the MEK/ERK signaling pathway.

RESULTS

The microarray analysis results showed that PLAC8 was most significantly downregulated in periodontium samples of patients with periodontitis, which participates in blood coagulation and integrin-mediated signaling pathway. PLAC8 was also markedly downregulated in the LPS-PG-treated hPDLCs. Moreover, overexpression of PLAC8 ameliorated inflammation and promoted cell mobility of LPS-PG-treated hPDLCs, while inhibition of PLAC8 exhibited the opposite effects. MEK/ERK was selected based on analyses of the protein-protein interaction (PPI) network as the potential signaling pathway interacted with PLAC8, and PLAC8 showed regulatory function on activation of the MEK/ERK pathway. Additionally, U0126, the inhibitor of MEK, abrogated the effects of PLAC8 on inflammation and cell mobility of LPS-PG-treated hPDLCs.

CONCLUSION

Overexpression of PLAC8 protected hPDLCs from dysfunction of inflammation and cell mobility via activating MEK/ERK pathway, indicating a novel therapeutic target for periodontitis.

Multifaced roles of PLAC8 in cancer

The role of PLAC8 in tumorigenesis has been gradually elucidated with the development of research. Although there are common molecular mechanisms that enforce cell growth, the impact of PLAC8 is varied and can, in some instances, have opposite effects on tumorigenesis. To systematically understand the role of PLAC8 in tumors, the molecular functions of PLAC8 in cancer will be discussed by focusing on how PLAC8 impacts tumorigenesis when it arises within tumor cells and how these roles can change in different stages of cancer progression with the ultimate goal of suppressing PLAC8-relevant cancer behavior and related pathologies. In addition, we highlight the diversity of PLAC8 in different tumors and its functional output beyond cancer cell growth. The comprehension of PLAC8's molecular function might provide new target and lead to the development of novel anticancer therapies.

PLAC8 promotes adriamycin resistance via blocking autophagy in breast cancer

Adriamycin (ADM) is currently one of the most effective chemotherapeutic agents in breast cancer treatment. However, growing resistance to ADM could lead to treatment failure and poor outcome. PLAC8 was reported as a novel highly conserved protein and functioned as an oncogene or tumour suppressor in various tumours. Here, we found higher PLAC8 expression was correlated with worse outcome and aggressive phenotype in breast cancer. Breast cancer patients with higher PLAC8 expression showed potential ADM resistance. In vitro experiments further confirmed that PLAC8 inhibited by siRNA or enforced overexpression by infecting pcDNA3.1(C)-PLAC8 plasmid correspondingly decreased or increased ADM resistance. Subsequently, we demonstrated that ectopic PLAC8 expression in MCF-7/ADMR cell blocked the accumulation of the autophagy-associated protein LC3 and resulted in cellular accumulation of p62. Rapamycin-triggered autophagy significantly increased cell response to ADM, while the autophagy inhibitor 3-MA enhanced ADM resistance. 3-MA and PLAC8 could synergistically cause ADM resistance via blocking the autophagy process. Additionally, the down-regulation of p62 by siRNA attenuated the activation of autophagy and PLAC8 expression in breast cancer cells. Thus, our findings suggest that PLAC8, through the participation of p62, inhibits autophagy and consequently results in ADM resistance in breast cancer. PLAC8/p62 pathway may act as novel therapeutic targets in breast cancer treatment and has potential clinical application in overcoming ADM resistance.

PLAC8 gene knockout increases the radio-sensitivity of xenograft tumors in nude mice with nasopharyngeal carcinoma by promoting apoptosis

In vitro cell experiments showed that knocking out the placenta-specific protein 8 (PLAC8) gene significantly increased the sensitivity of tumor cells to radiation. This study used two nude mouse models of nasopharyngeal carcinoma (NPC) to investigate the radio-sensitization and molecular mechanism of PLAC8 knockout in vivo. The expression of PLAC8 in 120 NPC tissues and 30 nasopharyngitis (NPG) tissues was detected by immunohistochemistry (IHC) to analyze the relationship between PLAC8 and neck lymph node metastasis and prognosis in NPC patients. The mRNA expression level of PLAC8 in several NPC cell lines was detected by semi-quantitative RT-PCR. The PLAC8 gene was knocked out in CNE-2 cells using CRISPR/Cas9. The effect of PLAC8 gene knockout on the radiotherapy sensitivity of NPC cells was analyzed by establishing model 1 and model 2 tumor-bearing nude mouse models with two different irradiation methods. The expression of γH2AX, Bax, Bcl-2, Caspase-3 and cleaved Caspase-3 was detected by immunofluorescence (IF), IHC and western blot analysis. PLAC8 expression was significantly increased in NPC tissue samples and NPC cell lines compared with NPG tissue samples and normal cell lines (P<0.01). PLAC8 upregulation was associated with lymph node metastasis and a poor prognosis in patients with NPC (P<0.01). Both animal models showed that radiotherapy after PLAC8 knockout significantly slowed tumor growth and reduced tumor volume, with tumor inhibition rates of 100% and 66.04%, respectively. In model 2, PLAC8 knockout with radiotherapy increased the expressions of γH2AX, Bax, Caspase-3 and cleaved Caspase-3 but decreased the expression of Bcl-2 (P<0.01). In model 1, there was no tumor formation at the site where the cancer cells were injected. The expression levels of γH2AX, Bax, Caspase-3 and cleaved Caspase-3 in skin tissues taken at the injection site were lower than those in NPC tissues treated with radiotherapy, while the expression level of Bcl-2 was higher (P<0.01). PLAC8 expression is closely related to neck metastasis and the prognosis of NPC. PLAC8 gene knockout significantly increases the radio-sensitivity of NPC cells in vivo by promoting apoptosis, which is an effective strategy for the radiotherapy sensitization of NPC.

Autophagy Process in Trophoblast Cells Invasion and Differentiation: Similitude and Differences With Cancer Cells

Early human placental development begins with blastocyst implantation, then the trophoblast differentiates and originates the cells required for a proper fetal nutrition and placental implantation. Among them, extravillous trophoblast corresponds to a non-proliferating trophoblast highly invasive that allows the vascular remodeling which is essential for appropriate placental perfusion and to maintain the adequate fetal growth. This process involves different placental cell types as well as molecules that allow cell growth, cellular adhesion, tissular remodeling, and immune tolerance. Remarkably, some of the cellular processes required for proper placentation are common between placental and cancer cells to finally support tumor growth. Indeed, as in placentation trophoblasts invade and migrate, cancer cells invade and migrate to promote tumor metastasis. However, while these processes respond to a controlled program in trophoblasts, in cancer cells this regulation is lost. Interestingly, it has been shown that autophagy, a process responsible for the degradation of damaged proteins and organelles to maintain cellular homeostasis, is required for invasion of trophoblast cells and for vascular remodeling during placentation. In cancer cells, autophagy has a dual role, as it has been shown both as tumor promoter and inhibitor, depending on the stage and tumor considered. In this review, we summarized the similarities and differences between trophoblast cell invasion and cancer cell metastasis specifically evaluating the role of autophagy in both processes.

Clinical significance of CD34+CD117dim/CD34+CD117bri myeloblast-associated gene expression in t(8;21) acute myeloid leukemia

t(8;21)(q22;q22) acute myeloid leukemia (AML) is a highly heterogeneous hematological malignancy with a high relapse rate in China. Two leukemic myeloblast populations (CD34⁺CD117^dim and CD34⁺CD117^bri) were previously identified in t(8;21) AML, and CD34⁺CD117^dim cell proportion was determined as an independent factor for this disease outcome. Here, we examined the impact of CD34⁺CD117^dim/CD34⁺CD117^bri myeloblast-associated gene expression on t(8;21) AML clinical prognosis. In this study, 85 patients with t(8;21) AML were enrolled. The mRNA expression levels of CD34⁺CD117^dim-associated genes (LGALS1, EMP3, and CRIP1) and CD34⁺CD117^bri-associated genes (TRH, PLAC8, and IGLL1) were measured using quantitative reverse transcription PCR. Associations between gene expression and clinical outcomes were determined using Cox regression models. Results showed that patients with high LGALS1, EMP3, or CRIP1 expression had significantly inferior overall survival (OS), whereas those with high TRH or PLAC8 expression showed relatively favorable prognosis. Univariate analysis revealed that CD19, CD34⁺CD117^dim proportion, KIT mutation, minimal residual disease (MRD), and expression levels of LGALS1, EMP3, CRIP1, TRH and PLAC8 were associated with OS. Multivariate analysis indicated that KIT mutation, MRD and CRIP1 and TRH expression levels were independent prognostic variables for OS. Identifying the clinical relevance of CD34⁺CD117^dim/CD34⁺CD117^bri myeloblast-associated gene expression may provide new clinically prognostic markers for t(8;21) AML.

Regulation of tamoxifen sensitivity by the PLAC8/MAPK pathway axis is antagonized by curcumin-induced protein stability change

Tamoxifen resistance remains the major obstacle to the estrogen receptor positive breast cancer endocrine therapy. Placenta-specific 8 (PLAC8) has been implicated in epithelial-mesenchymal transition and tumorigenesis. However, the molecular mechanisms underlying PLAC8 function in the context of tamoxifen resistance are unclear. Curcumin has attracted considerable attention in the last decades. It is isolated from Curcuma longa and has beneficial effects in cancer therapy. We studied this property by using MCF-7 and tamoxifen-resistant breast cancer cells (MCF-7/TAM) cell lines. PLAC8 can regulate MCF-7/TAM cell drug sensitivity through the MAPK/ERK pathway and shows the potential effects of curcumin or as a possible druggable target against tamoxifen failure.

Morusin induces apoptosis and autophagy via JNK, ERK and PI3K/Akt signaling in human lung carcinoma cells

Due to drug resistance and side effects, the development of novel therapeutics for the treatment of lung cancer is still in an urgent need. Morusin, a naturally occurring prenylated flavonoid isolated from the root bark of Morus alba, has been reported to be a promising candidate for cancer treatment including lung cancer. This study aimed to validate the anti-cancer effects of morusin in human non-small cell lung cancer (NSCLC) cell lines A549 and NCI-H292. The results indicated that morusin had growth inhibitory, pro-apoptotic and pro-autophagic effects on A549 and NCI-H292 cells. The induction of apoptosis was characterized by chromatin condensation and PARP cleavage. Mitochondrial membrane potential (MMP) loss, cytochrome c release, Bax/Bcl-2 dysregulation, and caspase-3 cleavage were also observed, indicating a mitochondria-dependent apoptosis was induced by morusin. A pro-autophagic effect was demonstrated by the increased level of LC3-Ⅱ and decreased level of SQSTM1/p62. Furthermore, morusin inhibited PI3K/Akt signaling and activated JNK, ERK pathways as indicated by the alteration in the ratio of phosphorylation level over total protein expression level. A PI3K/Akt inhibitor (LY294002), a JNK inhibitor (SP600125) and a MEK/ERK inhibitor (U0126) contributed to the determination that these pathways were involved in both apoptosis and autophagy induced by morusin. Moreover, morusin treatment strikingly enhanced intracellular ROS level, an ROS scavenger NAC blocked cell death and changes of Akt, JNK and ERK induced by morusin.

PLAC8 inhibits oral squamous cell carcinogenesis and epithelial-mesenchymal transition via the Wnt/β-catenin and PI3K/Akt/GSK3β signaling pathways

Placenta-specific 8 (PLAC8) is closely associated with the proliferation, apoptosis and autophagy of several tumor cells. However, the expression and function of PLAC8 in oral squamous cell carcinoma (OSCC) remain unknown. Therefore, the present study investigated the function and mechanism of PLAC8 in OSCC. Reverse transcription-quantitative PCR and western blot analyses were performed to quantify the expression of PLAC8 in OSCC cell lines. The function of PLAC8 in OSCC was investigated via transfection, the Transwell and Cell Counting Kit-8 assays, immunofluorescence staining and western blotting. The results demonstrated that PLAC8 exspression was downregulated in OSCC cell lines. PLAC8 inhibited the cell proliferation in OSCC. In addition, PLAC8 restrained invasion and epithelial-mesenchymal transition of OSCC cells. Furthermore, β-catenin helped to repress PLAC8 expression by regulating the Wnt/β-catenin and PI3K/Akt/GSK3β signaling pathways in OSCC cells. Collectively, the results of the present study suggest that PLAC8 acts as a tumor suppressor in OSCC by downregulating β-catenin.

Identification of Energy Metabolism Genes for the Prediction of Survival in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) samples were clustered into three energy metabolism-related molecular subtypes (C1, C2, and C3) with different prognosis using the gene expression data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). HCC energy metabolism-related molecular subtype analysis was conducted based on the 594 energy metabolism genes. Differential expression analysis yielded 576 differentially expressed genes (DEGs) among the three subtypes, which were closely related to HCC progression. Six genes were finally selected from the 576 DEGs through LASSO-Cox regression and used in constructing a six-gene signature-associated prognostic risk model, which was validated using the TCGA internal and three GEO external validation cohorts. The risk model showed that high ANLN, ENTPD2, TRIP13, PLAC8, and G6PD expression levels were associated with bad prognosis, and high expression of ADH1C was associated with a good prognosis. The validation results showed that our risk model had a high distinguishing ability of prognosis in HCC patients. The four enriched pathways of the risk model were obtained by gene set enrichment analysis (GSEA) and found to be associated with the tumorigenesis and development of HCC, including the cell cycle, Wnt signaling pathway, drug metabolism cytochrome P450, and primary bile acid biosynthesis. The risk score calculated from the established risk model in 204 samples and other clinical characteristics were used in building a nomogram with a good prognostic prediction ability (C-index = 0.746, 95% CI = 0.714-0.777). The area under the curves (AUCs) of the nomogram model in 1-, 2-, and 3-years were 0.82, 0.77, and 0.79, respectively. Then, qRT-PCR and immunohistochemistry were used to validate the mRNA expression levels of the six genes, and significant differences in mRNA and gene expression were observed among the tumor and adjacent tissues. Overall, our study divided HCC patients into three energy metabolism-related molecular subtypes with different prognosis. Then, a risk model with a good performance in prognostic prediction was built using the TCGA dataset. This model can be used as an independent prognostic evaluation index for HCC patients.

Placenta-specific 8 limits IFNγ production by CD4 T cells in vitro and promotes establishment of influenza-specific CD8 T cells in vivo

During type 1 immune responses, CD4 T helper 1 (Th1) cells and CD8 T cells are activated via IL-12 and contribute to the elimination of intracellular pathogens through interferon gamma (IFNγ) production. In this study, we identified Placenta-specific 8 (Plac8) as a gene that is uniquely expressed in Th1 CD4 T cells relative to other CD4 T cell subsets and hypothesized that Plac8 may represent a novel therapeutic target in Th1 CD4 T cells. First, we determined that Plac8 mRNA in CD4 T cells was induced following IL-12 stimulation via an indirect route that required new protein synthesis. Upon evaluating the functional relevance of Plac8 expression in Th1 CD4 T cells, we discovered that Plac8 was important for suppressing IFNγ mRNA and protein production by CD4 T cells 24 hours after IL-12 stimulation, however Plac8 did not contribute to pathogenic CD4 T cell function during two models of intestinal inflammation. We also noted relatively high basal expression of Plac8 in CD8 T cells which could be further induced following IL-12 stimulation in CD8 T cells. Furthermore, Plac8 expression was important for establishing an optimal CD8 T cell response against influenza A virus via a T cell-intrinsic manner. Altogether, these results implicate Plac8 as a potential regulator of Th1 CD4 and CD8 T cell responses during Th1 T cell-driven inflammation.

PLCA8 suppresses breast cancer apoptosis by activating the PI3k/AKT/NF-κB pathway

The cysteine‐rich lysosomal protein placenta‐specific 8 (PLAC8), also called onzin, has been shown to be involved in many types of cancers, and its role is highly dependent on cellular and physiological contexts. However, the precise function of PLAC8 in breast cancer (BC) progression remains unclear. In this study, we investigated both the clinical significance and biological functions of PLAC8 in BC progression. First, high PLAC8 expression was observed in primary BC tissues compared with adjacent normal tissues through immunohistochemistry analysis. The results of in vitro and in vivo assays further confirmed that PLAC8 overexpression promotes cell proliferation and suppress BC cell apoptosis, whereas PLAC8 silencing has the opposite effect. In addition, the forced expression of PLAC8 greatly induces cell migration, partially by affecting the EMT‐related genes, including down‐regulating E‐cadherin expression and facilitating vimentin expression. Further mechanistic analysis confirmed that PLAC8 contributes to cell proliferation and suppresses cell apoptosis in BC by activating the PI3K/AKT/NF‐κB pathway. The results of our study provide new insights into an oncogenic role of PLAC8 and reveal a novel PLAC8/ PI3K/AKT/NF‐κB pathway as a potential therapeutic target for BC.