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result(s) for
"Chen, Junjie"
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Biological and clinical aspects of HPV-related cancers
2020
Cancer-related diseases represent the second overall cause of death worldwide. Human papilloma virus (HPV) is an infectious agent which is mainly sexually transmitted and may lead to HPV-associated cancers in both men and women. Almost all cervical cancers are HPV-associated, however, an increasing number of head and neck cancers (HNCs), especially oropharyngeal cancer, can be linked to HPV infection. Moreover, anogenital cancers, including vaginal, vulvar, penial, and anal cancers, represent a subset of HPV-related cancers. Whereas testing and prevention of cervical cancer have significantly improved over past decades, anogenital cancers remain more difficult to confirm. Current clinical trials including patients with HPV-related cancers focus on finding proper testing for all HPV-associated cancers as well as improve the currently applied treatments. The HPV viral oncoproteins, E6 and E7, lead to degradation of, respectively, p53 and pRb resulting in entering the S phase without G1 arrest. These high-risk HPV viral oncogenes alter numerous cellular processes, including DNA repair, angiogenesis, and/or apoptosis, which eventually result in carcinogenesis. Additionally, a comprehensive analysis of gene expression and alteration among a panel of DNA double strand breaks (DSB) repair genes in HPV-negative and HPV-positive HNC cancers reveals differences pointing to HPV-dependent modifications of DNA repair processes in these cancers. In this review, we discuss the current knowledge regarding HPV-related cancers, current screening, and treatment options as well as DNA damage response-related biological aspects of the HPV infection and clinical trials.
Journal Article
METTL3-mediated m6A modification of HDGF mRNA promotes gastric cancer progression and has prognostic significance
2020
ObjectiveN6-methyladenosine (m6A) RNA methylation and its associated methyltransferase METTL3 are involved in tumour initiation and progression via the regulation of RNA function. This study explored the biological function and clinical significance of METTL3 in gastric cancer (GC).DesignThe prognostic value of METTL3 expression was evaluated using tissue microarray and immunohistochemical staining analyses in a human GC cohort. The biological role and mechanism of METTL3 in GC tumour growth and liver metastasis were determined in vitro and in vivo.ResultsThe level of m6A RNA was significantly increased in GC, and METTL3 was the main regulator involved in the abundant m6A RNA modification. METTL3 expression was significantly elevated in GC tissues and associated with poor prognosis. Multivariate Cox regression analysis revealed that METTL3 expression was an independent prognostic factor and effective predictor in human patients with GC. Moreover, METTL3 overexpression promoted GC proliferation and liver metastasis in vitro and in vivo. Mechanistically, P300-mediated H3K27 acetylation activation in the promoter of METTL3 induced METTL3 transcription, which stimulated m6A modification of HDGF mRNA, and the m6A reader IGF2BP3 then directly recognised and bound to the m6A site on HDGF mRNA and enhanced HDGF mRNA stability. Secreted HDGF promoted tumour angiogenesis, while nuclear HDGF activated GLUT4 and ENO2 expression, followed by an increase in glycolysis in GC cells, which was correlated with subsequent tumour growth and liver metastasis.ConclusionsElevated METTL3 expression promotes tumour angiogenesis and glycolysis in GC, indicating that METTL3 expression is a potential prognostic biomarker and therapeutic target for human GC.
Journal Article
Fine-grained restoration of Mongolian patterns based on a multi-stage deep learning network
2024
Mongolian patterns are easily damaged by various factors in the process of inheritance and preservation, and the traditional manual restoration methods are time-consuming, laborious, and costly. With the development of deep learning technology and the rapid growth of the image restoration field, the existing image restoration methods are mostly aimed at natural scene images. They do not apply to Mongolian patterns with complex line texture structures and high saturation-rich colors. In order to solve this problem, this paper proposes a Mongolian pattern restoration model with a multi-stage network. In the first stage, a pyramid context encoder network is introduced to learn the contextual features of the image for global restoration; in the second stage, a local restoration network is constructed by combining the RIC convolutional layer and the MPD down-sampling module; and in the third stage, the global refinement restoration is carried out by using the U-Net network that incorporates the attention mechanism. The experimental results show that this paper’s method achieves remarkable results in the Mongolian pattern repair task, using four evaluation metrics such as Peak Signal-to-Noise Ratio (PSNR), Structural Similarity (SSIM), LPIPS, and L1 Loss to compare with the existing method. The results show that this paper’s method performs well in the Mongolian pattern repair task. Also, the performance of the model on public datasets verifies its wide applicability. The method in this paper provides an efficient solution for the digital restoration of Mongolian motifs and has important application prospects.
Journal Article
A H2O2-activatable nanoprobe for diagnosing interstitial cystitis and liver ischemia-reperfusion injury via multispectral optoacoustic tomography and NIR-II fluorescent imaging
2021
Developing high-quality NIR-II fluorophores (emission in 1000–1700 nm) for in vivo imaging is of great significance. Benzothiadiazole-core fluorophores are an important class of NIR-II dyes, yet ongoing limitations such as aggregation-caused quenching in aqueous milieu and non-activatable response are still major obstacles for their biological applications. Here, we devise an activatable nanoprobe to address these limitations. A molecular probe named BTPE-NO
2
is synthesized by linking a benzothiadiazole core with two tetraphenylene groups serving as hydrophobic molecular rotors, followed by incorporating two nitrophenyloxoacetamide units at both ends of the core as recognition moieties and fluorescence quenchers. An FDA-approved amphiphilic polymer Pluronic F127 is then employed to encapsulate the molecular BTPE-NO
2
to render the nanoprobe BTPE-NO
2
@F127. The pathological levels of H
2
O
2
in the disease sites cleave the nitrophenyloxoacetamide groups and activate the probe, thereby generating strong fluorescent emission (950~1200 nm) and ultrasound signal for multi-mode imaging of inflammatory diseases. The nanoprobe can therefore function as a robust tool for detecting and imaging the disease sites with NIR-II fluorescent and multispectral optoacoustic tomography (MSOT) imaging. Moreover, the three-dimensional MSOT images can be obtained for visualizing and locating the disease foci.
Fluorescent imaging in the second biological window has advantages for in vivo applications. Here, the authors synthesise a molecular nanoprobe which activates upon binding H
2
O
2
, generating both strong fluorescent NIR-II emission and ultrasound signal for multi-mode imaging of inflammatory diseases.
Journal Article
FIGNL1-containing protein complex is required for efficient homologous recombination repair
by
Yuan, Jingsong
,
Chen, Junjie
in
Adenosine Triphosphatases - chemistry
,
Adenosine Triphosphatases - genetics
,
Adenosine Triphosphatases - metabolism
2013
The RAD51 recombinase plays a central role in homologous recombination (HR), which is critical for repair of DNA double-strand breaks, maintenance of genomic stability, and prevention of developmental disorders and cancer. Here, we report the identification of an RAD51-binding protein fidgetin-like 1 (FIGNL1). FIGNL1 specifically interacts with RAD51 through its conserved RAD51 binding domain. Cells depleted of FIGNL1 show defective HR repair. Interestingly, FIGNL1 is recruited to sites of DNA damage in a manner that is independent of breast cancer 2, early onset RAD51, and probably, RAD51 paralogs. Conversely, FIGNL1 depletion does not affect the loading of RAD51 onto ssDNA. Our additional analysis uncovered KIAA0146, also known as scaffolding protein involved in DNA repair (SPIDR), as a binding partner of FIGNL1 and established that KIAA0146/SPIDR acts with FIGNL1 in HR repair. Collectively, our study uncovers a protein complex, which consists of FIGNL1 and KIAA0146/SPIDR, in DNA repair and provides potential directions for cancer diagnosis and therapy.
Journal Article
Protein remote homology detection based on bidirectional long short-term memory
2017
Background
Protein remote homology detection plays a vital role in studies of protein structures and functions. Almost all of the traditional machine leaning methods require fixed length features to represent the protein sequences. However, it is never an easy task to extract the discriminative features with limited knowledge of proteins. On the other hand, deep learning technique has demonstrated its advantage in automatically learning representations. It is worthwhile to explore the applications of deep learning techniques to the protein remote homology detection.
Results
In this study, we employ the Bidirectional Long Short-Term Memory (BLSTM) to learn effective features from pseudo proteins, also propose a predictor called
ProDec-BLSTM
: it includes input layer, bidirectional LSTM, time distributed dense layer and output layer. This neural network can automatically extract the discriminative features by using bidirectional LSTM and the time distributed dense layer.
Conclusion
Experimental results on a widely-used benchmark dataset show that
ProDec-BLSTM
outperforms other related methods in terms of both the mean ROC and mean ROC50 scores. This promising result shows that
ProDec-BLSTM
is a useful tool for protein remote homology detection. Furthermore, the hidden patterns learnt by
ProDec-BLSTM
can be interpreted and visualized, and therefore, additional useful information can be obtained.
Journal Article
mTORC1 couples cyst(e)ine availability with GPX4 protein synthesis and ferroptosis regulation
2021
Glutathione peroxidase 4 (GPX4) utilizes glutathione (GSH) to detoxify lipid peroxidation and plays an essential role in inhibiting ferroptosis. As a selenoprotein, GPX4 protein synthesis is highly inefficient and energetically costly. How cells coordinate GPX4 synthesis with nutrient availability remains unclear. In this study, we perform integrated proteomic and functional analyses to reveal that SLC7A11-mediated cystine uptake promotes not only GSH synthesis, but also GPX4 protein synthesis. Mechanistically, we find that cyst(e)ine activates mechanistic/mammalian target of rapamycin complex 1 (mTORC1) and promotes GPX4 protein synthesis at least partly through the Rag-mTORC1-4EBP signaling axis. We show that pharmacologic inhibition of mTORC1 decreases GPX4 protein levels, sensitizes cancer cells to ferroptosis, and synergizes with ferroptosis inducers to suppress patient-derived xenograft tumor growth in vivo. Together, our results reveal a regulatory mechanism to coordinate GPX4 protein synthesis with cyst(e)ine availability and suggest using combinatorial therapy of mTORC1 inhibitors and ferroptosis inducers in cancer treatment.
Glutathione peroxidase 4 (GPX4) inhibits ferroptosis, but protein synthesis is inefficient and costly. Here, the authors reveal that cystine uptake promotes GPX4 synthesis by activating mTORC1 and show that cancer cells are sensitized to ferroptosis by mTORC1 inhibition.
Journal Article
Identification of Real MicroRNA Precursors with a Pseudo Structure Status Composition Approach
2015
Containing about 22 nucleotides, a micro RNA (abbreviated miRNA) is a small non-coding RNA molecule, functioning in transcriptional and post-transcriptional regulation of gene expression. The human genome may encode over 1000 miRNAs. Albeit poorly characterized, miRNAs are widely deemed as important regulators of biological processes. Aberrant expression of miRNAs has been observed in many cancers and other disease states, indicating they are deeply implicated with these diseases, particularly in carcinogenesis. Therefore, it is important for both basic research and miRNA-based therapy to discriminate the real pre-miRNAs from the false ones (such as hairpin sequences with similar stem-loops). Particularly, with the avalanche of RNA sequences generated in the postgenomic age, it is highly desired to develop computational sequence-based methods in this regard. Here two new predictors, called \"iMcRNA-PseSSC\" and \"iMcRNA-ExPseSSC\", were proposed for identifying the human pre-microRNAs by incorporating the global or long-range structure-order information using a way quite similar to the pseudo amino acid composition approach. Rigorous cross-validations on a much larger and more stringent newly constructed benchmark dataset showed that the two new predictors (accessible at http://bioinformatics.hitsz.edu.cn/iMcRNA/) outperformed or were highly comparable with the best existing predictors in this area.
Journal Article
Low-dose metformin targets the lysosomal AMPK pathway through PEN2
2022
Metformin, the most prescribed antidiabetic medicine, has shown other benefits such as anti-ageing and anticancer effects
1
–
4
. For clinical doses of metformin, AMP-activated protein kinase (AMPK) has a major role in its mechanism of action
4
,
5
; however, the direct molecular target of metformin remains unknown. Here we show that clinically relevant concentrations of metformin inhibit the lysosomal proton pump v-ATPase, which is a central node for AMPK activation following glucose starvation
6
. We synthesize a photoactive metformin probe and identify PEN2, a subunit of γ-secretase
7
, as a binding partner of metformin with a dissociation constant at micromolar levels. Metformin-bound PEN2 forms a complex with ATP6AP1, a subunit of the v-ATPase
8
, which leads to the inhibition of v-ATPase and the activation of AMPK without effects on cellular AMP levels. Knockout of
PEN2
or re-introduction of a PEN2 mutant that does not bind ATP6AP1 blunts AMPK activation. In vivo, liver-specific knockout of
Pen2
abolishes metformin-mediated reduction of hepatic fat content, whereas intestine-specific knockout of
Pen2
impairs its glucose-lowering effects. Furthermore, knockdown of
pen-2
in
Caenorhabditis elegans
abrogates metformin-induced extension of lifespan. Together, these findings reveal that metformin binds PEN2 and initiates a signalling route that intersects, through ATP6AP1, the lysosomal glucose-sensing pathway for AMPK activation. This ensures that metformin exerts its therapeutic benefits in patients without substantial adverse effects.
The molecular target of the antidiabetic medicine metformin is identified as PEN2, a subunit of γ-secretases, and the PEN2–ATP6AP1 axis offers potential targets for screening for metformin substitutes.
Journal Article
Recent progress in mass spectrometry proteomics for biomedical research
by
Xu Li;Wenqi Wang;Junjie Chen
in
Biomedical and Life Sciences
,
Biomedical research
,
Biomedical Research - methods
2017
Proteins are the key players in many cellular processes. Their composition, trafficking, and interactions underlie the dynamic processes of life. Furthermore, diseases are frequently accompanied by malfunction of proteins at multiple levels. Understanding how biological processes are regulated at the protein level is critically important to understanding the molecular basis for diseases and often shed light on disease prevention, diagnosis, and treatment. With rapid advances in mass spectrometry(MS)instruments and experimental methodologies, MS-based proteomics has become a reliable and essential tool for elucidating biological processes at the protein level. Over the past decade, we have witnessed great expansion of knowledge of human diseases with the application of MS-based proteomic technologies, which has led to many exciting discoveries. Herein we review the recent progress in MS-based proteomics in biomedical research, including that in establishing disease-related proteomes and interactomes. We also discuss how this progress will benefit biomedical research and clinical diagnosis and treatment of disease.
Journal Article