Pulmonary,cardiac and renal distribution of ACE2, furin,TMPRSS2 and ADAM17 in rats with heart failure: Potential implication for COVID-19 disease

Congestive heart failure (CHF) is often associated with kidney and pulmonary dysfunction. Activation of the renin-angiotensin-aldosterone system (RAAS) contributes to avid sodium retention, cardiac hypertrophy and oedema formation, including lung congestion. While the status of the classic components of RAAS such as renin, angiotensin converting enzyme (ACE), angiotensin II (Ang II) and angiotensin II receptor AT-1 is well studied in CHF, the expression of angiotensin converting enzyme-2 (ACE2), a key enzyme of angiotensin 1-7 (Ang 1-7) generation in the pulmonary, cardiac and renal systems has not been studied thoroughly in this clinical setting. This issue is of a special interest as Ang 1-7 counterbalance the vasoconstrictory, pro-inflammatory and pro-proliferative actions of Ang II. Furthermore, CHF predisposes to COVID-19 disease severity, while ACE2 also serves as the binding domain of SARS-CoV-2 in human host-cells, and acts in concert with furin, an important enzyme in the synthesis of BNP in CHF, in permeating viral functionality along TMPRSST2. ADAM17 governs ACE2 shedding from cell membranes. Therefore, the present study was designed to investigate the expression of ACE2, furin, TMPRSS2 and ADAM17 in the lung, heart and kidneys of rats with CHF to understand the exaggerated susceptibility of clinical CHF to COVID-19 disease. Heart failure was induced in male Sprague Dawley rats by the creation of a surgical aorto-caval fistula. Sham-operated rats served as controls. One week after surgery, the animals were subdivided into compensated and decompensated CHF according to urinary sodium excretion. Both groups and their controls were sacrificed, and their hearts, lungs and kidneys were harvested for assessment of tissue remodelling and ACE2, furin, TMPRSS2 and ADAM17 immunoreactivity, expression and immunohistochemical staining. ACE2 immunoreactivity and mRNA levels increased in pulmonary, cardiac and renal tissues of compensated, but not in decompensated CHF. Furin immunoreactivity was increased in both compensated and decompensated CHF in the pulmonary, cardiac tissues and renal cortex but not in the medulla. Interestingly, both the expression and abundance of pulmonary, cardiac and renal TMPRSS2 decreased in CHF in correlation with the severity of the disease. Pulmonary, cardiac and renal ADAM17 mRNA levels were also downregulated in decompensated CHF. Circulating furin levels increased in proportion to CHF severity, whereas plasma ACE2 remained unchanged. In summary, ACE2 and furin are overexpressed in the pulmonary, cardiac and renal tissues of compensated and to a lesser extent of decompensated CHF as compared with their sham controls. The increased expression of the ACE2 in heart failure may serve as a compensatory mechanism, counterbalancing the over-activity of the deleterious isoform, ACE. Downregulated ADAM17 might enhance membranal ACE2 in COVID-19 disease, whereas the suppression of TMPRSS2 in CHF argues against its involvement in the exaggerated susceptibility of CHF patients to SARS-CoV2.     

COVID-19 receptor and malignant cancers: Association of CTSL expression with susceptibility to SARS-CoV-2

CTSL is expressed by cancerous tissues and encodes a lysosomal cysteine proteinase that regulates cancer progression and SARS-CoV-2 entry. Therefore, it is critical to predict the susceptibility of cancer patients for SARS-CoV-2 and evaluate the correlation between disease outcomes and the expression of CTSL in malignant cancer tissues. In the current study, we analyzed CTSL expression, mutation rate, survival and COVID-19 disease outcomes in cancer and normal tissues, using online databases. We also performed immunohistochemistry (IHC) to test CTSL expression and western blot to monitor its regulation by cordycepin (CD), and N6, N6-dimethyladenosine (m⁶₂A), respectively. We found that CTSL is conserved across different species, and highly expressed in both normal and cancer tissues from human, as compared to ACE2 or other proteinases/proteases. Additionally, the expression of CTSL protein was the highest in the lung tissue. We show that the mRNA expression of CTSL is 66.4-fold higher in normal lungs and 54.8-fold higher in cancer tissues, as compared to ACE2 mRNA expression in the respective tissues. Compared to other proteases/proteinases/convertases such as TMPRSS2 and FURIN, the expression of CTSL was higher in both normal lungs and lung cancer samples. All these data indicate that CTSL might play an important role in COVID-19 pathogenesis in normal and cancer tissues of the lungs. Additionally, the CTSL-002 isoform containing both the inhibitor_I29 and Peptidase_C1 domains was highly prevalent in all cancers, suggesting its potential role in tumor progression and SARS-CoV-2 entry in multiple types of cancers. Further analysis of the expression of CTSL mutant showed a correlation with FURIN and TMPRSS2, suggesting a potential role of CTSL mutations in modulating SARS-CoV-2 entry in cancers. Moreover, high expression of CTSL significantly correlated with a short overall survival (OS) in lung cancer and glioma. Thus, CTSL might play a major role in the susceptibility of lung cancer and glioma patients to SARS-CoV-2 uptake and COVID-19 severity. Furthermore, CD or m⁶₂A inhibited CTSL expression in the cancer cell lines A549, MDA-MB-231, and/or PC3 in a dose dependent manner. In conclusion, we show that CTSL is highly expressed in normal tissues and increased in most cancers, and CD or m⁶₂A could inhibit its expression, suggesting the therapeutic potential of targeting CTSL for cancer and COVID-19 treatment.     

Evaluation and characterization of HSPA5 (GRP78) expression profiles in normal individuals and cancer patients with COVID-19

HSPA5 (BiP, GRP78) has been reported as a potential host-cell receptor for SARS-Cov-2, but its expression profiles on different tissues including tumors, its susceptibility to SARS-Cov-2 virus and severity of its adverse effects on malignant patients are unclear. In the current study, HSPA5 has been found to be expressed ubiquitously in normal tissues and significantly increased in 14 of 31 types of cancer tissues. In lung cancer, mRNA levels of HSPA5 were 253-fold increase than that of ACE2. Meanwhile, in both malignant tumors and matched normal samples across almost all cancer types, mRNA levels of HSPA5 were much higher than those of ACE2. Higher expression of HSPA5 significantly decreased patient overall survival (OS) in 7 types of cancers. Moreover, systematic analyses found that 7.15% of 5,068 COVID-19 cases have malignant cancer coincidental situations, and the rate of severe events of COVID-19 patients with cancers present a higher trend than that for all COVID-19 patients, showing a significant difference (33.33% vs 16.09%, p<0.01). Collectively, these data imply that the tissues with high HSPA5 expression, not low ACE2 expression, are susceptible to be invaded by SARS-CoV-2. Taken together, this study not only indicates the clinical significance of HSPA5 in COVID-19 disease and cancers, but also provides potential clues for further medical treatments and managements of COVID-19 patients.     

基于新型冠状病毒S蛋白结构及入胞机制的抗体与药物研发

新型冠状病毒肺炎,世界卫生组织命名为"2019冠状病毒病"(corona virus disease 2019,COVID-19),是一种由2019新型冠状病毒(2019-nCov)感染导致的肺炎.目前新冠肺炎在全球广泛流行,且疫情尚未得到全部控制.由于新型冠状病毒表面的刺突蛋白(spike protein,S)介导病...     

Co-expression of the SARS-CoV-2 entry molecules ACE2 and TMPRSS2 in human ovaries: Identification of cell types and trends with age

The high rate of SARS-CoV-2 infection poses a serious threat to public health. Previous studies have suggested that SARS-CoV-2 can infect human ovary, the core organ of the female reproductive system. However, it remains unclear which type of ovarian cells are easily infected by SARS-CoV-2 and whether ovarian infectivity differs from puberty to menopause. In this study, public datasets containing bulk and single-cell RNA-Seq data derived from ovarian tissues were analyzed to demonstrate the mRNA expression and protein distribution of the two key entry receptors for SARS-CoV-2—angiotensin-converting enzyme 2 (ACE2) and type II transmembrane serine protease (TMPRSS2). Furthermore, an immunohistochemical study of ACE2 and TMPRSS2 in human ovaries of different ages was conducted. Differentially expressed gene (DEG) analysis of ovaries of different ages and with varying ovarian reserves was conducted to explore the potential functions of ACE2 and TMPRSS2 in the ovary. The analysis of the public datasets indicated that the co-expression of ACE2 and TMPRSS2 was observed mostly in oocytes and partially in granulosa cells. However, no marked difference was observed in ACE2 or TMPRSS2 expression between young and old ovaries and ovaries with low and high reserves. Correspondingly, ACE2 and TMPRSS2 were detected in the human ovarian cortex and medulla, especially in oocytes of different stages, with no observed variations in their expression level in ovaries of different ages, which was consistent with the results of bioinformatic analyses. Remarkably, DEG analysis showed that a series of viral infection-related pathways were more enriched in ACE2-positive ovarian cells than in ACE2-negative ovarian cells, suggesting that SARS-CoV-2 may potentially target specific ovarian cells and affect ovarian function. However, further fundamental and clinical research is still needed to monitor the process of SARS-CoV-2 entry into ovarian cells and the long-term effects of SARS-CoV-2 infection on the ovarian function in recovered females.     

Hydroxychloroquine-mediated inhibition of SARS-CoV-2 entry is attenuated by TMPRSS2

Hydroxychloroquine, used to treat malaria and some autoimmune disorders, potently inhibits viral infection of SARS coronavirus (SARS-CoV-1) and SARS-CoV-2 in cell-culture studies. However, human clinical trials of hydroxychloroquine failed to establish its usefulness as treatment for COVID-19. This compound is known to interfere with endosomal acidification necessary to the proteolytic activity of cathepsins. Following receptor binding and endocytosis, cathepsin L can cleave the SARS-CoV-1 and SARS-CoV-2 spike (S) proteins, thereby activating membrane fusion for cell entry. The plasma membrane-associated protease TMPRSS2 can similarly cleave these S proteins and activate viral entry at the cell surface. Here we show that the SARS-CoV-2 entry process is more dependent than that of SARS-CoV-1 on TMPRSS2 expression. This difference can be reversed when the furin-cleavage site of the SARS-CoV-2 S protein is ablated or when it is introduced into the SARS-CoV-1 S protein. We also show that hydroxychloroquine efficiently blocks viral entry mediated by cathepsin L, but not by TMPRSS2, and that a combination of hydroxychloroquine and a clinically-tested TMPRSS2 inhibitor prevents SARS-CoV-2 infection more potently than either drug alone. These studies identify functional differences between SARS-CoV-1 and -2 entry processes, and provide a mechanistic explanation for the limited in vivo utility of hydroxychloroquine as a treatment for COVID-19.     

Molecular dynamic and bioinformatic studies of metformin-induced ACE2 phosphorylation in the presence of different SARS-CoV-2 S protein mutations

The SARS-CoV-2 infection activates host kinases and causes high phosphorylation in both the host and the virus. There were around 70 phosphorylation sites found in SARS-CoV-2 viral proteins. Besides, almost 15,000 host phosphorylation sites were found in SARS-CoV-2-infected cells. COVID-19 is thought to enter cells via the well-known receptor Angiotensin-Converting Enzyme 2 (ACE2) and the serine protease TMPRSS2. Substantially, the COVID-19 infection doesn’t induce phosphorylation of the ACE2 receptor at Serin-680(s680). Metformin's numerous pleiotropic properties and extensive use in medicine including COVID-19, have inspired experts to call it the “aspirin of the twenty-first century”. Metformin's impact on COVID-19 has been verified in clinical investigations via ACE2 receptor phosphorylation at s680. In the infection of COVID-19, sodium-dependent transporters including the major neutral amino acid (B⁰AT1) is regulated by ACE2. The structure of B⁰AT1 complexing with the COVID-19 receptor ACE2 enabled significant progress in the creation of mRNA vaccines. We aimed to study the impact of the interaction of the phosphorylation form of ACE2-s680 with wild-type (WT) and different mutations of SARS-CoV-2 infection such as delta, omicron, and gamma (γ) on their entrance of host cells as well as the regulation of B⁰AT1by the SARS-CoV-2 receptor ACE2. Interestingly, compared to WT SARS-CoV-2, ACE2 receptor phosphorylation at s680 produces conformational alterations in all types of SARS-CoV-2. Furthermore, our results showed for the first time that this phosphorylation significantly influences ACE2 sites K625, K676, and R678, which are key mediators for ACE2-B⁰AT1 complex.     

Single-cell RNA analysis on ACE2 expression provides insights into SARS-CoV-2 potential entry into the bloodstream and heart injury

Coronavirus disease-2019 (COVID-19) is a global pandemic with high infectivity and pathogenicity, accounting for tens of thousands of deaths worldwide. Recent studies have found that the pathogen of COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), shares the same cell receptor angiotensin converting enzyme II (ACE2) as SARS-CoV. The pathological investigation of COVID-19 deaths showed that the lungs had characteristics of pulmonary fibrosis. However, how SARS-CoV-2 spreads from the lungs to other organs has not yet been determined. Here, we performed an unbiased evaluation of cell-type-specific expression of ACE2 in healthy and fibrotic lungs, as well as in normal and failed adult human hearts, using published single-cell RNA-seq data. We found that ACE2 expression in fibrotic lungs mainly locates in arterial vascular cells, which might provide a route for bloodstream spreading of SARS-CoV-2. Failed human hearts have a higher percentage of ACE2-expressing cardiomyocytes, and SARS-CoV-2 might attack cardiomyocytes through the bloodstream in patients with heart failure. Moreover, ACE2 was highly expressed in cells infected by respiratory syncytial virus or Middle East respiratory syndrome coronavirus and in mice treated by lipopolysaccharide. Our findings indicate that patients with pulmonary fibrosis, heart failure, and virus infection have a higher risk and are more susceptible to SARS-CoV-2 infection. The SARS-CoV-2 might attack other organs by getting into the bloodstream. This study provides new insights into SARS-CoV-2 blood entry and heart injury and might propose a therapeutic strategy to prevent patients from developing severe complications.     

Low expression of TMPRSS2–a SARS-CoV-2 internalization protease–associates with basal subtype of head and neck squamous cell carcinoma

SARS-CoV-2 is a single-stranded RNA virus that has caused the ongoing COVID-19 pandemic. ACE2 and other genes utilized by SARS-CoV-2 to enter human cells have been shown to express in Head and Neck Squamous Cell Carcinoma (HNSCC) patients. However, their expression pattern in different subtypes has not been investigated. Hence, in the current study, we have analyzed the expression of ACE2, TMPRSS2 and FURIN in 649 HNSCC patients from two independent cohorts. Our analysis showed significantly lower expression of TMPRSS2 while significantly increased expression of ACE2 and FURIN in HPV-negative HNSCC. Comparison of expression of these genes in the three subtypes of HNSCC patients (basal, classical and inflamed/mesenchymal) showed no significant difference in the expression of ACE2 among the three subtypes; however, the basal subtype showed significantly reduced expression of TMPRSS2 but significantly increased expression of FURIN. Comparison of expression of these genes between the HPV-negative patients of basal subtype vs all others confirmed significantly lower expression of TMPRSS2 in HPV-negative patients of basal subtype as compared to all others. Our study shows that the different subtypes of HNSCC patients have different expression patterns of genes utilized by the SARS-CoV-2 to enter human cells, and hence, their susceptibility to SARS-CoV-2 may also be different. As the expression of TMPRSS2 is significantly lower in the HNSCC patients of the basal subtype, we predict that these patients would be less susceptible to SARS-CoV-2 infection than the patients of other subtypes. However, these findings need to be further validated.     

Phytopharmaceuticals mediated Furin and TMPRSS2 receptor blocking: can it be a potential therapeutic option for Covid-19?

BackgroundCurrently, novel coronavirus disease (Covid-19) outbreak creates global panic across the continents, as people from almost all countries and territories have been affected by this highly contagious viral disease. The scenario is deteriorating due to lack of proper & specific target-oriented pharmacologically safe prophylactic agents or drugs, and or any effective vaccine. drug development is urgently required to back in the normalcy in the community and to combat this pandemic.PurposeThus, we have proposed two novel drug targets, Furin and TMPRSS2, as Covid-19 treatment strategy. We have highlighted this target-oriented novel drug delivery strategy, based on their pathophysiological implication on SARS-CoV-2 infection, as evident from earlier SARS-CoV-1, MERS, and influenza virus infection via host cell entry, priming, fusion, and endocytosis.Study design &  MethodsAn earlier study suggested that Furin and TMPRSS2 knockout mice had reduced level of viral load and a lower degree of organ damage such as the lung. The present study thus highlights the promise of some selected novel and potential anti-viral Phytopharmaceutical that bind to Furin and TMPRSS2 as target.ResultFew of them had shown promising anti-viral response in both preclinical and clinical study with acceptable therapeutic safety-index.ConclusionHence, this strategy may limit life-threatening Covid-19 infection and its mortality rate through nano-suspension based intra-nasal or oral nebulizer spray, to treat mild to moderate SARS-COV-2 infection when Furin and TMPRSS2 receptor may initiate to express and activate for processing the virus to cause cellular infection by replication within the host cell and blocking of host-viral interaction.     

Downregulation of ACE2 expression by SARS-CoV-2 worsens the prognosis of KIRC and KIRP patients via metabolism and immunoregulation

Background: Angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) allow entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) into host cells and play essential roles in cancer therapy. However, the functions of ACE2 and TMPRSS2 in kidney cancer remain unclear, especially as kidneys are targets for SARS-CoV-2 infection.Methods: UCSC Xena project, the Cancer Genome Atlas (TCGA), and Gene Expression Omnibus (GEO) databases ({"type":"entrez-geo","attrs":{"text":"GSE30589","term_id":"30589"}}GSE30589 and {"type":"entrez-geo","attrs":{"text":"GSE59185","term_id":"59185"}}GSE59185) were searched for gene expression in human tissues, gene expression data, and clinical information. Several bioinformatics methods were utilized to analyze the correlation between ACE2 and TMPRSS2 with respect to the prognosis of kidney renal clear cell carcinoma (KIRC) and kidney renal papillary cell carcinoma (KIRP).Results: ACE2 expression was significantly upregulated in tumor tissue, while its downregulation was associated with low survival in KIRC and KIRP patients. TMPRSS2 was downregulated in KIRC and KIRP, and its expression was not correlated with patient survival. According to clinical risk factor-based prediction models, ACE2 exhibits predictive accuracy for kidney cancer prognosis and is correlated with metabolism and immune infiltration. In an animal model, ACE2 expression was remarkably downregulated in SARS-CoV-2-infected cells compared to in the control.Conclusion: ACE2 expression is highly correlated with various metabolic pathways and is involved in immune infiltration.it plays a crucial role than TMPRSS2 in diagnosing and prognosis of kidney cancer patients. The overlap in ACE2 expression between kidney cancer and SARS-CoV-2 infection suggests that patients with KIRC or KIRP are at high risk of developing serious symptoms.     

The possible double-edged sword effects of vitamin D on COVID-19: A hypothesis

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) gains access to host cells by attaching to angiotensin-converting enzyme 2 (ACE2). Vitamin D (VitD) can upregulate ACE2 and has an antagonistic effect on Renin, which exerts a vasodilatation and anti-inflammatory effect against coronavirus disease (COVID-19). However, it may also facilitate viral entry by increasing ACE2 as the main SARS-CoV-2 receptor and mediates ROS production through NADPH oxidase, as a double-edged sword effect. Lung function and the immune system are also influenced by VitD through several mechanisms, including increased natural antibiotics (Defensin and Cathelicidin) and upregulated transforming growth factor-β. A higher IgA, Th2/Th1 ratio, and T-regulatory cells are attributable to VitD effects on the immune cells, while these changes may also be a double-edged sword in COVID-19. Although VitD supplementation might be highly recommended in COVID-19, the administration's dosage and route could be challenging. Furthermore, this issue has not been mentioned in various studies so far. So, the report aimed to explain the current challenges with the application of VitD in COVID-19.     

TMPRSS2 promotes SARS-CoV-2 evasion from NCOA7-mediated restriction

Interferons play a critical role in regulating host immune responses to SARS-CoV-2, but the interferon (IFN)-stimulated gene (ISG) effectors that inhibit SARS-CoV-2 are not well characterized. The IFN-inducible short isoform of human nuclear receptor coactivator 7 (NCOA7) inhibits endocytic virus entry, interacts with the vacuolar ATPase, and promotes endo-lysosomal vesicle acidification and lysosomal protease activity. Here, we used ectopic expression and gene knockout to demonstrate that NCOA7 inhibits infection by SARS-CoV-2 as well as by lentivirus particles pseudotyped with SARS-CoV-2 Spike in lung epithelial cells. Infection with the highly pathogenic, SARS-CoV-1 and MERS-CoV, or seasonal, HCoV-229E and HCoV-NL63, coronavirus Spike-pseudotyped viruses was also inhibited by NCOA7. Importantly, either overexpression of TMPRSS2, which promotes plasma membrane fusion versus endosomal fusion of SARS-CoV-2, or removal of Spike’s polybasic furin cleavage site rendered SARS-CoV-2 less sensitive to NCOA7 restriction. Collectively, our data indicate that furin cleavage sensitizes SARS-CoV-2 Spike to the antiviral consequences of endosomal acidification by NCOA7, and suggest that the acquisition of furin cleavage may have favoured the co-option of cell surface TMPRSS proteases as a strategy to evade the suppressive effects of IFN-induced endo-lysosomal dysregulation on virus infection.     

SARS-CoV-2 cell receptor gene ACE2 -mediated immunomodulation in breast cancer subtypes

The recent outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has impacted the world severely. The binding of the SARS-CoV-2 virus to the angiotensin-converting enzyme 2 (ACE2) and its intake by the host cell is a necessary step for infection. ACE2 has garnered widespread therapeutic possibility as it is entry/interactive point for SARS-CoV-2, responsible for coronavirus disease 2019 (COVID-19) pandemic and providing a critical regulator for immune modulation in various disease. Patients with suffering from cancer always being on the verge of being immune compromised therefore gaining knowledge about how SARS-CoV-2 viruses affecting immune cells in human cancers will provides us new opportunities for preventing or treating virus-associated cancers. Despite COVID-19 pandemic got center stage at present time, however very little research being explores, which increase our knowledge in context with how SARS-CoV-2 infection affect cancer a cellular level. Therefore, in light of the ACE-2 as an important contributor of COVID-19 global, we analyzed correlation between ACE2 and tumor immune infiltration (TIL) level and the type markers of immune cells were investigated in breast cancer subtypes by using TIMER database. Our findings shed light on the immunomodulatory role of ACE2 in the luminal A subtype which may play crucial role in imparting therapeutic resistance in this cancer subtype.     

Malaria,COVID-19 and angiotensin-converting enzyme 2: what does the available population data say?

The etiopathogenesis of COVID-19 and its differential geographic spread suggest some populations are apparently ‘less affected’ through many host-related factors that involve angiotensin-converting enzyme 2 (ACE2) protein, which is also the entry receptor for SARS-CoV-2. The role of ACE2 has been well studied in COVID-19 but not in the context of malaria and COVID-19. We have previously suggested how malaria might intersect with COVID-19 through ACE2 mutation and here we evaluate the currently available data that could provide a link between the two diseases. Based on the existing global and Indian data on malaria, COVID-19 and the suggested ACE2 mutation, the association could not be examined robustly, neither accepting nor refuting the suggested hypothesis. We strongly recommend targeted evaluation of this hypothesis through carefully designed robust molecular epidemiological studies.     

新型冠状病毒抗体和小分子抑制剂的研究现状

世界卫生组织已宣布新型冠状病毒感染（coronavirus disease 2019,COVID-19）的爆发为全球大流行。中和抗体和小分子抑制剂在预防及治疗COVID-19中发挥重要作用。尽管已开发出了多种中和抗体以及疫苗,但是随着病原体严重急性呼吸综合征冠状病毒2(severe acute respiratory syndrome coronavirus 2,SARS-CoV-2)的不断变异,现有的抗体及疫苗面临巨大的挑战。小分子抑制剂主要通过干扰病毒与宿主的结合以及病毒自身的复制达到消灭病毒以及抑制病毒感染的作用,并且对SARS-CoV-2突变株具有广谱抑制作用,是当前研究的热点。近年来国内外学者对SARS-CoV-2的小分子抑制剂做了大量的研究工作,本文根据中和抗体识别的抗原表位以及小分子抑制剂的作用机制分别对用于预防及治疗COVID-19的中和抗体和小分子抑制剂进行综述,讨论其研究现状,并展望小分子抑制剂的应用前景,以期为该领域的进一步研究提供参考。