SPOP-mediated ubiquitination and degradation of PDK1 suppresses AKT kinase activity and oncogenic functions

SPARK regulates AGC kinases central to the Toxoplasma gondii asexual cycle

Apicomplexan parasites balance proliferation, persistence, and spread in their metazoan hosts. AGC kinases, such as PKG, PKA, and the PDK1 ortholog SPARK, integrate environmental signals to toggle parasites between replicative and motile life stages. Recent studies have cataloged pathways downstream of apicomplexan PKG and PKA; however, less is known about the global integration of AGC kinase signaling cascades. Here, conditional genetics coupled to unbiased proteomics demonstrates that SPARK complexes with an elongin-like protein to regulate the stability of PKA and PKG in the model apicomplexan Toxoplasma gondii. Defects attributed to SPARK depletion develop after PKG and PKA are down-regulated. Parasites lacking SPARK differentiate into the chronic form of infection, which may arise from reduced activity of a coccidian-specific PKA ortholog. This work delineates the signaling topology of AGC kinases that together control transitions within the asexual cycle of this important family of parasites.

Ginsenoside Rh2 shifts tumor metabolism from aerobic glycolysis to oxidative phosphorylation through regulating the HIF1-α/PDK4 axis in non-small cell lung cancer

BACKGROUND

Ginsenoside Rh2 (G-Rh2), a steroidal compound extracted from roots of ginseng, has been extensively studied in tumor therapy. However, its specific regulatory mechanism in non-small cell lung cancer (NSCLC) is not well understood. Pyruvate dehydrogenase kinase 4 (PDK4), a central regulator of cellular energy metabolism, is highly expressed in various malignant tumors. We investigated the impact of G-Rh2 on the malignant progression of NSCLC and how it regulated PDK4 to influence tumor aerobic glycolysis and mitochondrial function.

METHOD

We examined the inhibitory effect of G-Rh2 on NSCLC through I proliferation assay, migration assay and flow cytometry in vitro. Subsequently, we verified the ability of G-Rh2 to inhibit tumor growth and metastasis by constructing subcutaneous tumor and metastasis models in nude mice. Proteomics analysis was conducted to analyze the action pathways of G-Rh2. Additionally, we assessed glycolysis and mitochondrial function using seahorse, PET-CT, Western blot, and RT-qPCR.

RESULT

Treatment with G-Rh2 significantly inhibited tumor proliferation and migration ability both in vitro and in vivo. Furthermore, G-Rh2 inhibited the tumor's aerobic glycolytic capacity, including glucose uptake and lactate production, through the HIF1-α/PDK4 pathway. Overexpression of PDK4 demonstrated that G-Rh2 targeted the inhibition of PDK4 expression, thereby restoring mitochondrial function, promoting reactive oxygen species (ROS) accumulation, and inducing apoptosis. When combined with sodium dichloroacetate, a PDK inhibitor, it complemented the inhibitory capacity of PDKs, acting synergistically as a detoxifier.

CONCLUSION

G-Rh2 could target and down-regulate the expression of HIF-1α, resulting in decreased expression of glycolytic enzymes and inhibition of aerobic glycolysis in tumors. Additionally, by directly targeting mitochondrial PDK, it elevated mitochondrial oxidative phosphorylation and enhanced ROS accumulation, thereby promoting tumor cells to undergo normal apoptotic processes.

ELK3 destabilization by speckle-type POZ protein suppresses prostate cancer progression and docetaxel resistance

Accumulating evidence demonstrates that the activity regulation of ELK3, a member of the E26 transformation-specific oncogene family, is critical to regulating cell proliferation, migration, and survival in human cancers. However, the molecular mechanisms of how ELK3 induces chemoresistance in prostate cancer (PCa) have not been elucidated. In this study, we found that SPOP and ELK3 are an interacting partner. The interaction between SPOP and ELK3 resulted in increased ELK3 ubiquitination and destruction, assisted by checkpoint kinase-mediated ELK3 phosphorylation. Notably, the modulation of SPOP-mediated ELK3 protein stability affected the c-Fos-induced cell proliferation and invasion of PCa cells. The clinical involvement of the SPOP-ELK3 axis in PCa development was confirmed by an immunohistochemical assay on 123 PCa tissues, with an inverse correlation between increased ELK3 and decreased SPOP being present in ~80% of the specimens. This observation was supported by immunohistochemistry analysis using a SPOP-mutant PCa specimen. Finally, docetaxel treatment induced cell death by activating checkpoint kinase- and SPOP-mediated ELK3 degradation, while SPOP-depleted or SPOP-mutated PCa cells showed cell death resistance. Notably, this observation was correlated with the protein levels of ELK3. Taken together, our study reveals the precise mechanism of SPOP-mediated degradation of ELK3 and provides evidence that SPOP mutations contribute to docetaxel resistance in PCa.

Atypical inflammatory kinase IKBKE phosphorylates and inactivates FoxA1 to promote liver tumorigenesis

Physiologically, FoxA1 plays a key role in liver differentiation and development, and pathologically exhibits an oncogenic role in prostate and breast cancers. However, its role and upstream regulation in liver tumorigenesis remain unclear. Here, we demonstrate that FoxA1 acts as a tumor suppressor in liver cancer. Using a CRISPR-based kinome screening approach, noncanonical inflammatory kinase IKBKE has been identified to inhibit FoxA1 transcriptional activity. Notably, IKBKE directly binds to and phosphorylates FoxA1 to reduce its complex formation and DNA interaction, leading to elevated hepatocellular malignancies. Nonphosphorylated mimic Foxa1 knock-in mice markedly delay liver tumorigenesis in hydrodynamic transfection murine models, while phospho-mimic Foxa1 knock-in phenocopy Foxa1 knockout mice to exhibit developmental defects and liver inflammation. Notably, Ikbke knockout delays diethylnitrosamine (DEN)-induced mouse liver tumor development. Together, our findings not only reveal FoxA1 as a bona fide substrate and negative nuclear effector of IKBKE in hepatocellular carcinioma (HCC) but also provide a promising strategy to target IKBEK for HCC therapy.

SPOP promotes CREB5 ubiquitination to inhibit MET signaling in liver cancer

Liver cancer is ranked as the sixth most prevalent from of malignancy globally and stands as the third primary contributor to cancer-related mortality. Metastasis is the main reason for liver cancer treatment failure and patient deaths. Speckle-type POZ protein (SPOP) serves as a crucial substrate junction protein within the cullin-RING E3 ligase complex, acting as a significant tumor suppressor in liver cancer. Nevertheless, the precise molecular mechanism underlying the role of SPOP in liver cancer metastasis remain elusive. In the current study, we identified cAMP response element binding 5 (CREB5) as a novel SPOP substrate in liver cancer. SPOP facilitates non-degradative K63-polyubiquitination of CREB5 on K432 site, consequently hindering its capacity to activate receptor tyrosine kinase MET. Moreover, liver cancer-associated SPOP mutant S119N disrupts the SPOP-CREB5 interactions and impairs the ubiquitination of CREB5.This disruption ultimately leads to the activation of the MET signaling pathway and enhances metastatic properties of hepatoma cells both in vitro and in vivo. In conclusion, our findings highlight the functional significance of the SPOP-CREB5-MET axis in liver cancer metastasis.

SPOP inhibits HBV transcription and replication by ubiquitination and degradation of HNF1α

Hepatitis B virus (HBV) infection remains a significant public health burden worldwide. The persistence of covalently closed circular DNA (cccDNA) within the nucleus of infected hepatocytes is responsible for the failure of antiviral treatments. The ubiquitin proteasome system (UPS) has emerged as a promising antiviral target, as it can regulate HBV replication by promoting critical protein degradation in steps of viral life cycle. Speckle-type POZ protein (SPOP) is a critical adaptor for Cul3-RBX1 E3 ubiquitin ligase complex, but the effect of SPOP on HBV replication is less known. Here, we identified SPOP as a novel host antiviral factor against HBV infection. SPOP overexpression significantly inhibited the transcriptional activity of HBV cccDNA without affecting cccDNA level in HBV-infected HepG2-NTCP and primary human hepatocyte cells. Mechanism studies showed that SPOP interacted with hepatocyte nuclear factor 1α (HNF1α), and induced HNF1α degradation through host UPS pathway. Moreover, the antiviral role of SPOP was also confirmed in vivo. Together, our findings reveal that SPOP is a novel host factor which inhibits HBV transcription and replication by ubiquitination and degradation of HNF1α, providing a potential therapeutic strategy for the treatment of HBV infection.

Master kinase PDK1 in tumorigenesis

3-phosphoinositide-dependent protein kinase 1 (PDK1) is considered as master kinase regulating AGC kinase family members such as AKT, SGK, PLK, S6K and RSK. Although autophosphorylation regulates PDK1 activity, accumulating evidence suggests that PDK1 is manipulated by many other mechanisms, including S6K-mediated phosphorylation, and the E3 ligase SPOP-mediated ubiquitination and degradation. Dysregulation of these upstream regulators or downstream signals involves in cancer development, as PDK1 regulating cell growth, metastasis, invasion, apoptosis and survival time. Meanwhile, overexpression of PDK1 is also exposed in a plethora of cancers, whereas inhibition of PDK1 reduces cell size and inhibits tumor growth and progression. More importantly, PDK1 also modulates the tumor microenvironments and markedly influences tumor immunotherapies. In summary, we comprehensively summarize the downstream signals, upstream regulators, mouse models, inhibitors, tumor microenvironment and clinical treatments for PDK1, and highlight PDK1 as a potential cancer therapeutic target.

Conditional knockout of PDK1 in osteoclasts suppressed osteoclastogenesis and ameliorated prostate cancer-induced osteolysis in murine model

BACKGROUND

The development and maintenance of normal bone tissue is maintained by balanced communication between osteoblasts and osteoclasts. The invasion of cancer cells disrupts this balance, leading to osteolysis. As the only bone resorbing cells in vivo, osteoclasts play important roles in cancer-induced osteolysis. However, the role of 3-phosphoinositide-dependent protein kinase-1 (PDK1) in osteoclast resorption remains unclear.

METHODS

In our study, we used a receptor activator of nuclear factor-kappa B (RANK) promoter-driven Cre-LoxP system to conditionally delete the PDK1 gene in osteoclasts in mice. We observed the effect of osteoclast-specific knockout of PDK1 on prostate cancer-induced osteolysis. Bone marrow-derived macrophage cells (BMMs) were extracted and induced to differentiate osteoclasts in vitro to explore the role of PDK1 in osteoclasts.

RESULTS

In this study, we found that PDK1 conditional knockout (cKO) mice exhibited smaller body sizes when compared to the wild-type (WT) mice. Moreover, deletion of PDK1 in osteoclasts ameliorated osteolysis and rPDK1educed bone resorption markers in the murine model of prostate cancer-induced osteolysis. In vivo, we discovered that osteoclast-specific knockout of suppressed RANKL-induced osteoclastogenesis, bone resorption function, and osteoclast-specific gene expression (Ctsk, TRAP, MMP-9, NFATc1). Western blot analyses of RANKL-induced signaling pathways showed that conditional knockout of PDK1 in osteoclasts inhibited the early nuclear factor κB (NF-κB) activation, which consequently suppressed the downstream induction of NFATc1.

CONCLUSION

These findings demonstrated that PDK1 performs an important role in osteoclastogenesis and prostate cancer-induced osteolysis by modulating the PDK1/AKT/NF-κB signaling pathway.

PI3K/Akt signaling in urological cancers: Tumorigenesis function, therapeutic potential, and therapy response regulation

In addition to environmental conditions, lifestyle factors, and chemical exposure, aberrant gene expression and mutations involve in the beginning and development of urological tumors. Even in Western nations, urological malignancies are among the top causes of patient death, and their prevalence appears to be gender dependent. The prognosis for individuals with urological malignancies remains dismal and unfavorable due to the ineffectiveness of conventional treatment methods. PI3K/Akt is a popular biochemical mechanism that is activated in tumor cells as a result of PTEN loss. PI3K/Akt escalates growth and metastasis. Moreover, due to the increase in tumor cell viability caused by PI3K/Akt activation, cancer cells may acquire resistance to treatment. This review article examines the function of PI3K/Akt in major urological tumors including bladder, prostate, and renal tumors. In prostate, bladder, and kidney tumors, the level of PI3K and Akt are notably elevated. In addition, the activation of PI3K/Akt enhances the levels of Bcl-2 and XIAP, hence increasing the tumor cell survival rate. PI3K/Akt ] upregulates EMT pathways and matrix metalloproteinase expression to increase urological cancer metastasis. Furthermore, stimulation of PI3K/Akt results in drug- and radio-resistant cancers, but its suppression by anti-tumor drugs impedes the tumorigenesis.

Multiple forms of cell death: A focus on the PI3K/AKT pathway

Cell death is a natural biological process that occurs in living organisms. Since 1963, extensive research has shed light on the occurrence, progress, and final outcome of cell death. According to different cell phenotypes, it is classified into different types, including apoptosis, pyroptosis, necroptosis, autophagy, ferroptosis, cuproptosis, and so on. However, regardless of the form of cell death, what we ultimately expect is the disappearance of abnormal cells, such as tumor cells, while normal cells survive. As a result, it is vital to investigate the details of cell death, including death triggers, potent regulators, and executioners. Although significant progress has been made in understanding molecular pathways of cell death, many aspects remain unclear because of the complex regulatory networks in cells. Among them, the phosphoinositide-3-kinase (PI3K)/protein kinase B(AKT) pathway is discovered to be a crucial regulator of the cell death process. AKT, as a proto-oncogene, has become a major focus of attention in the medical community due to its role in regulating a multiplicity of cellular functions counting metabolism, immunity, proliferation, survival, transcription, and protein synthesis. Here, we explored the connection between the PI3K/AKT pathway and cell death, aiming to enhance our comprehension of the mechanism underlying this process. Such knowledge may pave the way for the subsequent development of more effective disease treatments, such as finding suitable targets for drug intervention.

Targeting PI3K/Akt signaling in prostate cancer therapy

Urological cancers have obtained much attention in recent years due to their mortality and morbidity. The most common and malignant tumor of urological cancers is prostate cancer that imposes high socioeconomic costs on public life and androgen-deprivation therapy, surgery, and combination of chemotherapy and radiotherapy are employed in its treatment. PI3K/Akt signaling is an oncogenic pathway responsible for migration, proliferation and drug resistance in various cancers. In the present review, the role of PI3K/Akt signaling in prostate cancer progression is highlighted. The activation of PI3K/Akt signaling occurs in prostate cancer, while PTEN as inhibitor of PI3K/Akt shows down-regulation. Stimulation of PI3K/Akt signaling promotes survival of prostate tumor cells and prevents apoptosis. The cell cycle progression and proliferation rate of prostate tumor cells increase by PI3K/Akt signaling induction. PI3K/Akt signaling stimulates EMT and enhances metastasis of prostate tumor cells. Silencing PI3K/Akt signaling impairs growth and metastasis of prostate tumor cells. Activation of PI3K/Akt signaling mediates drug resistance and reduces radio-sensitivity of prostate tumor cells. Anti-tumor compounds suppress PI3K/Akt signaling in impairing prostate tumor progression. Furthermore, upstream regulators such as miRNAs, lncRNAs and circRNAs regulate PI3K/Akt signaling and it has clinical implications for prostate cancer patients.

SPOP targets the immune transcription factor IRF1 for proteasomal degradation

Adaptation of the functional proteome is essential to counter pathogens during infection, yet precisely timed degradation of these response proteins after pathogen clearance is likewise key to preventing autoimmunity. Interferon regulatory factor 1 (IRF1) plays an essential role as a transcription factor in driving the expression of immune response genes during infection. The striking difference in functional output with other IRFs is that IRF1 also drives the expression of various cell cycle inhibiting factors, making it an important tumor suppressor. Thus, it is critical to regulate the abundance of IRF1 to achieve a 'Goldilocks' zone in which there is sufficient IRF1 to prevent tumorigenesis, yet not too much which could drive excessive immune activation. Using genetic screening, we identified the E3 ligase receptor speckle type BTB/POZ protein (SPOP) to mediate IRF1 proteasomal turnover in human and mouse cells. We identified S/T-rich degrons in IRF1 required for its SPOP MATH domain-dependent turnover. In the absence of SPOP, elevated IRF1 protein levels functionally increased IRF1-dependent cellular responses, underpinning the biological significance of SPOP in curtailing IRF1 protein abundance.

ACE2 in chronic disease and COVID-19: gene regulation and post-translational modification

Angiotensin-converting enzyme 2 (ACE2), a counter regulator of the renin-angiotensin system, provides protection against several chronic diseases. Besides chronic diseases, ACE2 is the host receptor for SARS-CoV or SARS-CoV-2 virus, mediating the first step of virus infection. ACE2 levels are regulated by transcriptional, post-transcriptional, and post-translational regulation or modification. ACE2 transcription is enhanced by transcription factors including Ikaros, HNFs, GATA6, STAT3 or SIRT1, whereas ACE2 transcription is reduced by the transcription factor Brg1-FoxM1 complex or ERRα. ACE2 levels are also regulated by histone modification or miRNA-induced destabilization. The protein kinase AMPK, CK1α, or MAP4K3 phosphorylates ACE2 protein and induces ACE2 protein levels by decreasing its ubiquitination. The ubiquitination of ACE2 is induced by the E3 ubiquitin ligase MDM2 or UBR4 and decreased by the deubiquitinase UCHL1 or USP50. ACE2 protein levels are also increased by the E3 ligase PIAS4-mediated SUMOylation or the methyltransferase PRMT5-mediated ACE2 methylation, whereas ACE2 protein levels are decreased by AP2-mediated lysosomal degradation. ACE2 is downregulated in several human chronic diseases like diabetes, hypertension, or lung injury. In contrast, SARS-CoV-2 upregulates ACE2 levels, enhancing host cell susceptibility to virus infection. Moreover, soluble ACE2 protein and exosomal ACE2 protein facilitate SARS-CoV-2 infection into host cells. In this review, we summarize the gene regulation and post-translational modification of ACE2 in chronic disease and COVID-19. Understanding the regulation and modification of ACE2 may help to develop prevention or treatment strategies for ACE2-mediated diseases.

Cooperative activation of PDK1 and AKT by MAPK4 enhances cancer growth and resistance to therapy

Phosphoinositide-dependent kinase-1 (PDK1) is a master kinase of the protein A, G, and C (AGC) family kinases that play important roles in regulating cancer cell proliferation, survival, and metabolism. Besides phosphorylating/activating AKT at the cell membrane in a PI3K-dependent manner, PDK1 also exhibits constitutive activity on many other AGC kinases for tumor-promoting activity. In the latter case, PDK1 protein levels dominate its activity. We previously reported that MAPK4, an atypical MAPK, can PI3K-independently promote AKT activation and tumor growth. Here, using triple-negative breast cancer (TNBC) cell models, we demonstrate that MAPK4 can also enhance PDK1 protein synthesis, thus phosphorylate/activate PDK1 substrates beyond AKT. This new MAPK4-PDK1 axis alone lacks vigorous tumor-promoting activity but cooperates with our previously reported MAPK4-AKT axis to promote tumor growth. Besides enhancing resistance to PI3K blockade, MAPK4 also promotes cancer cell resistance to the more stringent PI3K and PDK1 co-blockade, a recently proposed therapeutic strategy. Currently, there is no MAPK4 inhibitor to treat MAPK4-high cancers. Based on the concerted action of MAPK4-AKT and MAPK4-PDK1 axis in promoting cancer, we predict and confirm that co-targeting AKT and PDK1 effectively represses MAPK4-induced cancer cell growth, suggesting a potential therapeutic strategy to treat MAPK4-high cancers.

The therapeutic mechanism of transcranial iTBS on nerve regeneration and functional recovery in rats with complete spinal cord transection

Background

After spinal cord transection injury, the inflammatory microenvironment formed at the injury site, and the cascade of effects generated by secondary injury, results in limited regeneration of injured axons and the apoptosis of neurons in the sensorimotor cortex (SMC). It is crucial to reverse these adverse processes for the recovery of voluntary movement. The mechanism of transcranial intermittent theta-burst stimulation (iTBS) as a new non-invasive neural regulation paradigm in promoting axonal regeneration and motor function repair was explored by means of a severe spinal cord transection.

Methods

Rats underwent spinal cord transection and 2 mm resection of spinal cord at T10 level. Four groups were studied: Normal (no lesion), Control (lesion with no treatment), sham iTBS (lesion and no functional treatment) and experimental, exposed to transcranial iTBS, 72 h after spinal lesion. Each rat received treatment once a day for 5 days a week; behavioral tests were administered one a week. Inflammation, neuronal apoptosis, neuroprotective effects, regeneration and synaptic plasticity after spinal cord injury (SCI) were determined by immunofluorescence staining, western blotting and mRNA sequencing. For each rat, anterograde tracings were acquired from the SMC or the long descending propriospinal neurons and tested for cortical motor evoked potentials (CMEPs). Regeneration of the corticospinal tract (CST) and 5-hydroxytryptamine (5-HT) nerve fibers were analyzed 10 weeks after SCI.

Results

When compared to the Control group, the iTBS group showed a reduced inflammatory response and reduced levels of neuronal apoptosis in the SMC when tested 2 weeks after treatment. Four weeks after SCI, the neuroimmune microenvironment at the injury site had improved in the iTBS group, and neuroprotective effects were evident, including the promotion of axonal regeneration and synaptic plasticity. After 8 weeks of iTBS treatment, there was a significant increase in CST regeneration in the region rostral to the site of injury. Furthermore, there was a significant increase in the number of 5-HT nerve fibers at the center of the injury site and the long descending propriospinal tract (LDPT) fibers in the region caudal to the site of injury. Moreover, CMEPs and hindlimb motor function were significantly improved.

Conclusion

Neuronal activation and neural tracing further verified that iTBS had the potential to provide neuroprotective effects during the early stages of SCI and induce regeneration effects related to the descending motor pathways (CST, 5-HT and LDPT). Furthermore, our results revealed key relationships between neural pathway activation, neuroimmune regulation, neuroprotection and axonal regeneration, as well as the interaction network of key genes.

LncRNAs and regulated cell death in tumor cells

Regulated Cell Death (RCD) is a mode of cell death that occurs through drug or genetic intervention. The regulation of RCDs is one of the significant reasons for the long survival time of tumor cells and poor prognosis of patients. Long non-coding RNAs (lncRNAs) which are involved in the regulation of tumor biological processes, including RCDs occurring on tumor cells, are closely related to tumor progression. In this review, we describe the mechanisms of eight different RCDs which contain apoptosis, necroptosis, pyroptosis, NETosis, entosis, ferroptosis, autosis and cuproptosis. Meanwhile, their respective roles in the tumor are aggregated. In addition, we outline the literature that is related to the regulatory relationships between lncRNAs and RCDs in tumor cells, which is expected to provide new ideas for tumor diagnosis and treatment.

AMPK phosphorylates and stabilises copper transporter 1 to synergise metformin and copper chelator for breast cancer therapy

BACKGROUND

Predominant roles of copper and its transporter, copper transporter 1 (CTR1), in tumorigenesis have been explored recently; however, the upstream regulation of CTR1 and combinational intervention of copper chelators in malignancies remain largely unclear.

METHODS

CRISPR/Cas9-based kinome screening was used to identify the CTR1 upstream kinases. Immunofluorescence assays were utilised to detect CTR1 localisation. In vitro kinase assays and mass spectrometry were performed to detect CTR1 phosphorylation. Ubiquitination assays were performed to validate CTR1 stability. Colony formation, EdU labelling, Annexin V-FITC/PI-based apoptosis assays were carried out to detect the drug effect on cell growth and apoptosis. Xenografted mouse models were employed to investigate drug effects in vivo.

RESULTS

We identify that CTR1 undergoes AMPK-mediated phosphorylation, which enhances CTR1 stabilisation and membrane translocation by affecting Nedd4l interaction, resulting in increased oncogenic roles in breast cancer. Importantly, activation of AMPK with its agonist metformin markedly enhances CTR1 levels, and leads to the combinational usage of AMPK agonists and copper chelators for breast cancer treatment.

CONCLUSIONS

Our findings not only reveal the crosstalk between energy response and copper uptake via AMPK-mediated CTR1 phosphorylation and stability but also highlight the strategy to combat breast cancer by a combination of AMPK agonists and copper chelators.

SIGNIFICANCE

The connection between energy response and copper homoeostasis is linked by AMPK phosphorylating and stabilising CTR1, which provides a promising strategy to combat breast cancer by combining AMPK agonists and copper chelators.

Highly potent Platinum(IV) complexes with multiple-bond ligands targeting mitochondria to overcome cisplatin resistance

The efficacy and resistance of cisplatin-based compounds are very intractable problems at present. This study reports a series of platinum(IV) compounds containing multiple-bond ligands, which exhibited better tumor cell inhibitory activity and antiproliferative and anti-metastasis activities than cisplatin. The meta-substituted compounds 2 and 5 were particularly excellent. Further research showed that compounds 2 and 5 possessed appropriate reduction potential and performed significantly better than cisplatin in cellular uptake, reactive oxygen species response, the up-regulation of apoptosis and DNA lesion-related genes, and drug-resistant cell activity. The title compounds exhibited better antitumor potential and fewer side effects than cisplatin in vivo. Multiple-bond ligands were introduced into cisplatin to form the title compounds in this study, which not only enhanced their absorption and overcame drug resistance but also demonstrated the potential to target mitochondria and inhibit the detoxification of tumor cells.

Addressing the Reciprocal Crosstalk between the AR and the PI3K/AKT/mTOR Signaling Pathways for Prostate Cancer Treatment

The reduction in androgen synthesis and the blockade of the androgen receptor (AR) function by chemical castration and AR signaling inhibitors represent the main treatment lines for the initial stages of prostate cancer. Unfortunately, resistance mechanisms ultimately develop due to alterations in the AR pathway, such as gene amplification or mutations, and also the emergence of alternative pathways that render the tumor less or, more rarely, completely independent of androgen activation. An essential oncogenic axis activated in prostate cancer is the phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway, as evidenced by the frequent alterations of the negative regulator phosphatase and tensin homolog (PTEN) and by the activating mutations in PI3K subunits. Additionally, crosstalk and reciprocal feedback loops between androgen signaling and the PI3K/AKT/mTOR signaling cascade that activate pro-survival signals and play an essential role in disease recurrence and progression have been evidenced. Inhibitors addressing different players of the PI3K/AKT/mTOR pathway have been evaluated in the clinic. Only a limited benefit has been reported in prostate cancer up to now due to the associated side effects, so novel combination approaches and biomarkers predictive of patient response are urgently needed. Here, we reviewed recent data on the crosstalk between AR signaling and the PI3K/AKT/mTOR pathway, the selective inhibitors identified, and the most advanced clinical studies, with a focus on combination treatments. A deeper understanding of the complex molecular mechanisms involved in disease progression and treatment resistance is essential to further guide therapeutic approaches with improved outcomes.

Gene signature and prognostic value of ubiquitination-related genes in endometrial cancer

Protein ubiquitination is closely related to tumor occurrence and development. The specific role of ubiquitination in endometrial cancer remains largely unclear. Therefore, we constructed a novel endometrial cancer prognostic model based on ubiquitination-related genes. We extracted the expression matrices of ubiquitination-related genes from the Cancer Genome Atlas database, upon which we performed univariate Cox regression and least absolute shrinkage and selection operator (LASSO) regression analyses to obtain 22 ubiquitination-related genes for the construction of the prognostic model. Survival, regression, clinical correlation, and principal component analyses were performed to assess the performance of the model. Drug sensitivity analysis was performed based on these ubiquitination-related genes. Finally, a prognostic nomogram was constructed based on the prognostic model to quantify patient outcomes. Survival, regression, clinical correlation, and principal component analyses revealed that the performance of the prognostic model was satisfactory. Drug sensitivity analysis provided a potential direction for the treatment of endometrial cancer. The prognostic nomogram could be used to effectively estimate the survival rate of patients with endometrial cancer. In summary, we constructed a new endometrial cancer prognostic model and identified 5 differentially expressed, prognosis-associated, ubiquitination-related genes. These 5 genes are potential diagnostic and treatment targets for endometrial cancer.

USP20 is a predictor of poor prognosis in colorectal cancer and associated with lymph node metastasis, immune infiltration and chemotherapy resistance

Background

Colorectal cancer (CRC) is a highly prevalent malignancy with a poor prognosis. USP20 can support progression of variety of tumors. USP20 was shown to promote breast tumor metastasis, and proliferation of oral squamous carcinoma cells. However, the role of USP20 in CRC remains unclear.

Methods

We used bioinformatics to analyze the expression and prognosis of USP20 in pan-cancer and explore the relationship between USP20 expression and immune infiltration, immune checkpoints, and chemotherapy resistance in CRC. The differential expression and prognostic role of USP20 in CRC was validated by qRT-PCR and immunohistochemistry. Cox univariate and multivariate analyses were performed to assess risk factors for poor prognosis of CRC, and new prognostic prediction models were constructed and evaluated by decision curve analysis (ROC) and receiver operating characteristic (DCA). USP20 was overexpressed in CRC cell lines to explore the effect of USP20 on the functionalities of CRC cells. Enrichment analyses were used to explore the possible mechanism of USP20 in CRC.

Results

The expression of USP20 was lower in CRC tissues than adjacent normal tissues. Compared with low USP20 expression patients, CRC patients with high USP20 expression level had shorter OS. Correlation analysis showed that USP20 expression was associated with lymph node metastasis. Cox regression analysis revealed USP20 as an independent risk factor for poor prognosis in CRC patients. ROC and DCA analyses showed that the performance of the newly constructed prediction model was better than the traditional TNM model. Immune infiltration analysis shown that USP20 expression is closely associated with T cell infiltration in CRC. A co-expression analysis showed that USP20 expression was positively correlated with several immune checkpoint genes including ADORA2A, CD160, CD27 and TNFRSF25 genes and positively associated with multiple multi-drug resistance genes such as MRP1, MRP3, and MRP5 genes. USP20 expression positively correlated with the sensitivity of cells to multiple anticancer drugs. Overexpression of USP20 enhanced the migration and invasive ability of CRC cells. Enrichment pathway analyses showed the USP20 may play a role via the Notch pathway, Hedgehog pathway and beta-catenin pathway.

Conclusion

USP20 is downregulated in CRC and associated with prognosis in CRC. USP20 enhances CRC cells metastasis and is associated with immune infiltration, immune checkpoints, and chemotherapy resistance.

Sustained Aurora Kinase B Expression Confers Resistance to PI3K Inhibition in Head and Neck Squamous Cell Carcinoma

Tumor suppressor mutations in head and neck squamous cell carcinoma (HNSCC) dominate the genomic landscape, hindering the development of effective targeted therapies. Truncating and missense mutations in NOTCH1 are frequent in HNSCC, and inhibition of PI3K can selectively target NOTCH1 mutant (NOTCH1MUT) HNSCC cells. In this study, we identify several proteins that are differentially regulated in HNSCC cells after PI3K inhibition based on NOTCH1MUT status. Expression of Aurora kinase B (Aurora B), AKT, and PDK1 following PI3K inhibition was significantly lower in NOTCH1MUT cell lines than in wild-type NOTCH1 (NOTCH1WT) cells or NOTCH1MUT cells with acquired resistance to PI3K inhibition. Combined inhibition of PI3K and Aurora B was synergistic, enhancing apoptosis in vitro and leading to durable tumor regression in vivo. Overexpression of Aurora B in NOTCH1MUT HNSCC cells led to resistance to PI3K inhibition, while Aurora B knockdown increased sensitivity of NOTCH1WT cells. In addition, overexpression of Aurora B in NOTCH1MUT HNSCC cells increased total protein levels of AKT and PDK1. AKT depletion in NOTCH1WT cells and overexpression in NOTCH1MUT cells similarly altered sensitivity to PI3K inhibition, and manipulation of AKT levels affected PDK1 but not Aurora B levels. These data define a novel pathway in which Aurora B upregulates AKT that subsequently increases PDK1 selectively in NOTCH1MUT cells to mediate HNSCC survival in response to PI3K inhibition. These findings may lead to an effective therapeutic approach for HNSCC with NOTCH1MUT while sparing normal cells.

SIGNIFICANCE

Aurora B signaling facilitates resistance to PI3K inhibition in head and neck squamous cell carcinoma, suggesting that combined inhibition of PI3K and Aurora kinase is a rational therapeutic strategy to overcome resistance.

MiR-22-3p regulates the proliferation, migration and invasion of colorectal cancer cells by directly targeting KDM3A through the Hippo pathway

Colorectal cancer (CRC) has one of the highest incidences and mortality rates of all malignancies worldwide. microRNAs (miRNAs) have been reported to be involved in many biological processes of diseases. MiR-22-3p is considered to be involved in cancer progression, but its role in CRC remains unclear. In this study, we detected that in CRC, the level of miR-22-3p is downregulated. MiR-22-3p has antitumor effects in CRC. miR-22-3p can reduce the proliferative, invasive and migrative capacity of CRC cells. Luciferase reporter analyses confirmed that KDM3A was a target of miR-22-3p, which can directly target the 3'UTR of KDM3A and decrease the expression of KDM3A in CRC cells. Our study also confirmed that KDM3A plays a role as an oncogene in CRC. KDM3A overexpression attenuated the tumor suppressor effects of miR-22-3p in CRC cells, demonstrating that miR-22-3p exerts antitumor effects by targeting KDM3A. Overexpression of miR-22-3p in CRC reduced YAP1 expression, whereas overexpression of KDM3A restored the expression of YAP1. In summary, miR-22-3p might inhibit the progression of CRC by targeting KDM3A to regulate the HIPPO signaling pathway, which may provide an opportunity for the treatment of CRC.

Complexities of Prostate Cancer

Prostate cancer has a long disease history and a wide variety and uncertainty in individual patients' clinical progress. In recent years, we have seen a revolutionary advance in both prostate cancer patient care and in the research field. The power of deep sequencing has provided cistromic and transcriptomic knowledge of prostate cancer that has not discovered before. Our understanding of prostate cancer biology, from bedside and molecular imaging techniques, has also been greatly advanced. It is important that our current theragnostic schemes, including our diagnostic modalities, therapeutic responses, and the drugs available to target non-AR signaling should be improved. This review article discusses the current progress in the understanding of prostate cancer biology and the recent advances in diagnostic and therapeutic strategies.

SPOP in Cancer: Phenomena, Mechanisms and Its Role in Therapeutic Implications

Speckle-type POZ (pox virus and zinc finger protein) protein (SPOP) is a cullin 3-based E3 ubiquitin ligase adaptor protein that plays a crucial role in ubiquitin-mediated protein degradation. Recently, SPOP has attracted major research attention as it is frequently mutated in a range of cancers, highlighting pleiotropic tumorigenic effects and associations with treatment resistance. Structurally, SPOP contains a functionally critical N-terminal meprin and TRAF homology (MATH) domain for many SPOP substrates. SPOP has two other domains, including the internal Bric-a-brac-Tramtrack/Broad (BTB) domain, which is linked with SPOP dimerization and binding to cullin3, and a C-terminal nuclear localization sequence (NLS). The dysregulation of SPOP-mediated proteolysis is associated with the development and progression of different cancers since abnormalities in SPOP function dysregulate cellular signaling pathways by targeting oncoproteins or tumor suppressors in a tumor-specific manner. SPOP is also involved in genome stability through its role in the DNA damage response and DNA replication. More recently, studies have shown that the expression of SPOP can be modulated in various ways. In this review, we summarize the current understanding of SPOP's functions in cancer and discuss how to design a rational therapeutic target.

Therapeutic mechanism of transcranial iTBS on nerve regeneration and functional recovery in rats with complete spinal cord transection.. [DOI: 10.21203/rs.3.rs-2026215/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background: After spinal cord transection injury, the inflammatory microenvironment formed in the injury site and the cascade of secondary injury results in limited regeneration of injured axons and the apoptosis of neurons in the sensorimotor cortex (SMC). It is crucial to reverse these adverse processes for the recovery of voluntary movement. In this study, transcranial intermittent theta-burst stimulation (iTBS) was used for the treatment of complete spinal cord transection in rats. The mechanism of transcranial iTBS as a new non-invasive neural regulation paradigm in promoting axonal regeneration and motor function repair was explored. Methods: Rats from the iTBS group were treated with transcranial iTBS 72h after spinal cord injury (SCI). Each rat was received behavioral testing. Inflammation, neuronal apoptosis, neuroprotective effect, regeneration and synaptic plasticity were measured by immunofluorescence staining, western blotting and mRNA sequencing 2 or 4w after SCI. Each rat was received anterograde tracings in the SMC or the long descending propriospinal neurons and tested for motor evoked potentials. Regeneration of corticospinal tract (CST) and 5-hydroxytryptamine (5-HT) nerve fibers were detected eight weeks after SCI. Results: Compared with the control group and the sham iTBS group, rats of the iTBS group showed reduced inflammatory responses and neuronal apoptosis in the SMC two weeks after treatment. After four weeks, the neuroimmune microenvironment at the injury site was improved, and neuroprotective effects were seen to promote axonal regeneration and synaptic plasticity. Significantly, eight weeks after treatment, transcranial iTBS also increased the regeneration of CST, 5-HT nerve fibers, and the long descending propriospinal tract (LDPT). Moreover, motor evoked potentials and hindlimb motor function were significantly improved at eight weeks. Conclusions: Collectively, our results verified that iTBS has the potential to provide neuroprotective effects at early injury stages and pro-regeneration effects related to the 1) CST–5-HT; 2) CST–LDPT; and 3) CST–5-HT–LDPT descending motor pathways and revealed the relationships among neural pathway activation, neuroimmune regulation, neuroprotection, and axonal regeneration, as well as the interaction network of key genes. The proposed non-invasive transcranial iTBS treatment is expected to provide a serviceable practical and theoretical support for spinal cord injury.

Comprehensive analysis of TP53 and SPOP mutations and their impact on survival in metastatic prostate cancer

Background

Although TP53 and SPOP are frequently mutated in metastatic prostate cancer (PCa), their prognostic value is ambiguous, and large sample studies are lacking, especially when they co-occur with other genetic alterations.

Methods

Genomic data and patients’ clinical characteristics in PCa were downloaded from the cBioPortal database. We extensively analyzed other gene alterations in different mutation status of TP53 and SPOP. We further subdivided TP53 and SPOP mutation into subgroups based on different mutation status, and then evaluated the prognostic value. Two classification systems for TP53 survival analysis were used.

Results

A total of 2,172 patients with PCa were analyzed in our study, of which 1,799 were metastatic PCa patients. The mutual exclusivity analysis showed that TP53 and SPOP mutation has a strong mutual exclusion (p<0.001). In multivariable analysis, truncating TP53 mutations (HR=1.773, 95%CI:1.403-2.239, p<0.001) and other TP53 mutations(HR=1.555, 95%CI:1.267-1.908, p<0.001) were independent negative prognostic markers in metastatic PCa, whereas SPOP mutations(HR=0.592, 95%CI:0.427-0.819, p<0.001) were an independent prognostic factor for better prognosis. Mutations in TP53 were significantly associated with wild-type status for SPOP and CDK12, structural variants/fusions for TMPRSS2 and ERG, AR amplification and PTEN deletion (p<0.001). And truncating TP53 mutations have higher AR amplification rates than other TP53 mutations (p=0.022). Consistently, truncating TP53 mutations had a worse prognosis than other TP53 mutations (p<0.05). Then Kaplan-Meier survival curve showed that Co-occurring TP53 mutations in AR amplification or PTEN deletion tumors significantly reduced survival (p<0.05). Furthermore, those with SPOP-mutant tumors with co-occurring TP53 truncating mutations had shorter overall survival than those with SPOP-mutant tumors with wild-type or other TP53 mutations.

Conclusions

This study found that TP53 and SPOP mutations were mutually exclusive and both were independent prognostic markers for metastatic PCa. Genomic alteration and survival analysis revealed that TP53 and SPOP mutations represented distinct molecular subtypes. Our data suggest that molecular stratification on the basis of TP53 and SPOP mutation status should be implemented for metastatic PCa to optimize and modify clinical decision-making.

Functional roles of E3 ubiquitin ligases in prostate cancer

Prostate cancer (PCa) is a malignant epithelial tumor of the prostate gland with a high male cancer incidence. Numerous studies indicate that abnormal function of ubiquitin-proteasome system (UPS) is associated with the progression and metastasis of PCa. E3 ubiquitin ligases, key components of UPS, determine the specificity of substrates, and substantial advances of E3 ubiquitin ligases have been reached recently. Herein, we introduce the structures and functions of E3 ubiquitin ligases and summarize the mechanisms of E3 ubiquitin ligases-related PCa signaling pathways. In addition, some progresses in the development of inhibitors targeting E3 ubiquitin ligases are also included.

Novel insights into the SPOP E3 ubiquitin ligase: From the regulation of molecular mechanisms to tumorigenesis

Ubiquitin-mediated protein degradation is the primary biological process by which protein abundance is regulated and protein homeostasis is maintained in eukaryotic cells. Speckle-type pox virus and zinc finger (POZ) protein (SPOP) is a typical substrate adaptor of the Cullin 3-RING ligase (CRL3) family; it serves as a bridge between the Cullin 3 (Cul3) scaffold protein and its substrates. In recent years, SPOP has received increasing attention because of its versatility in its regulatory pathways and the diversity of tumor types involved. Mechanistically, SPOP substrates are involved in a wide range of biological processes, and abnormalities in SPOP function perturb downstream biological processes and promote tumorigenesis. Additionally, liquid-liquid phase separation (LLPS), a potential mechanism of membraneless organelle formation, was recently found to mediate the self-triggered colocalization of substrates with higher-order oligomers of SPOP. Herein, we summarize the structure of SPOP and the specific mechanisms by which it mediates the efficient ubiquitination of substrates. Additionally, we review the biological functions of SPOP, the regulation of SPOP expression, the role of SPOP in tumorigenesis and its therapeutic value.

SPOP Inhibition of Endometrial Carcinoma and Its Clinicopathological Relationship

Objective

Endometrial carcinoma (EC) ranks first in the incidence of female genital malignancies in developed countries. SPOP (speckle-type POZ protein) has changed in EC with a statistically high frequency. This research may play a crucial role in the initiation and progression of EC, ultimately leading to fresh therapeutic targets. Explore the expression of SPOP in EC; observe its effect on the proliferation, invasion, and migration of EC cells after upregulating the expression of SPOP through RNA activation.

Methods

The expression levels of SPOP protein in 150 EC tissues and 45 normal endometrial tissues were detected by immunohistochemistry and Western blotting. Analyze the relationship between SPOP expression and clinicopathological characteristics. The differences of the proliferation, migration, and invasion abilities between before and after transfection were analyzed using CCK-8 and Transwell assays.

Results

The results of immunohistochemistry and Western blotting showed the expression level of SPOP in EC tissue significantly reduced or even missed compared with normal endometrial tissue. The results of CCK-8 showed that the growth of EC significantly slowed down after the upregulating of SPOP expression. The results of the Transwell assay showed the migration and invasion abilities of EC cells were weakened after the level of SPOP was upregulated.

Conclusions

The expression level of SPOP in EC tissues is lower and related to the clinicopathological features compared with normal endometrial tissues. After upregulating the SPOP expression by RNA activation in EC cell lines, the abilities of proliferation, migration, and invasion of cells were significantly inhibited.

S6K1-mediated phosphorylation of PDK1 impairs AKT kinase activity and oncogenic functions

Functioning as a master kinase, 3-phosphoinositide-dependent protein kinase 1 (PDK1) plays a fundamental role in phosphorylating and activating protein kinases A, B and C (AGC) family kinases, including AKT. However, upstream regulation of PDK1 remains largely elusive. Here we report that ribosomal protein S6 kinase beta 1 (S6K1), a member of AGC kinases and downstream target of mechanistic target of rapamycin complex 1 (mTORC1), directly phosphorylates PDK1 at its pleckstrin homology (PH) domain, and impairs PDK1 interaction with and activation of AKT. Mechanistically, S6K1-mediated phosphorylation of PDK1 augments its interaction with 14-3-3 adaptor protein and homo-dimerization, subsequently dissociating PDK1 from phosphatidylinositol 3,4,5 triphosphate (PIP₃) and retarding its interaction with AKT. Pathologically, tumor patient-associated PDK1 mutations, either attenuating S6K1-mediated PDK1 phosphorylation or impairing PDK1 interaction with 14-3-3, result in elevated AKT kinase activity and oncogenic functions. Taken together, our findings not only unravel a delicate feedback regulation of AKT signaling via S6K1-mediated PDK1 phosphorylation, but also highlight the potential strategy to combat mutant PDK1-driven cancers.

The direct upstream regulation of PDK1 is not fully understood. Here the authors demonstrate that S6K1 directly phosphorylates PDK1 to inhibit AKT kinase activity and its ability to drive tumourigenesis.

Post-translational modifications on mitochondrial metabolic enzymes in cancer

Mitochondrion is the powerhouse of the cell. The research of nearly a century has expanded our understanding of mitochondrion, far beyond the view that mitochondrion is an important energy generator of cells. During the initiation, growth and survival of tumor cells, significant mitochondrial metabolic changes have taken place in the important enzymes of respiratory chain and tricarboxylic acid cycle, mitochondrial biogenesis and dynamics, oxidative stress regulation and molecular signaling. Therefore, mitochondrial metabolic proteins are the key mediators of tumorigenesis. Post-translational modification is the molecular switch that regulates protein function. Understanding how these mitochondria-related post-translational modification function during tumorigenesis will bring new ideas for the next generation of cancer treatment.

Phosphoinositide-Dependent Protein Kinases Regulate Cell Cycle Progression Through the SAD Kinase Cdr2 in Fission Yeast

Aberration in the control of cell cycle contributes to the development and progression of many diseases including cancers. Ksg1 is a Schizosaccharomyces pombe fission yeast homolog of mammalian phosphoinositide-dependent protein kinase 1 (PDK1) which is regarded as a signaling hub for human tumorigenesis. A previous study reported that Ksg1 plays an important role in cell cycle progression, however, the underlying mechanism remains elusive. Our genomic library screen for novel elements involved in Ksg1 function identified two serine/threonine kinases, namely SAD family kinase Cdr2 and another PDK1 homolog Ppk21, as multicopy suppressors of the thermosensitive phenotype of ksg1-208 mutant. We found that overexpression of Ppk21 or Cdr2 recovered the defective cell cycle transition of ksg1-208 mutant. In addition, ksg1-208 Δppk21 cells showed more marked defects in cell cycle transition than each single mutant. Moreover, overexpression of Ppk21 failed to recover the thermosensitive phenotype of the ksg1-208 mutant when Cdr2 was lacking. Notably, the ksg1-208 mutation resulted in abnormal subcellular localization and decreased abundance of Cdr2, and Ppk21 deletion exacerbated the decreased abundance of Cdr2 in the ksg1-208 mutant. Intriguingly, expression of a mitotic inducer Cdc25 was significantly decreased in ksg1-208, Δppk21, or Δcdr2 cells, and overexpression of Ppk21 or Cdr2 partially recovered the decreased protein level of Cdc25 in the ksg1-208 mutant. Altogether, our findings indicated that Cdr2 is a novel downstream effector of PDK1 homologs Ksg1 and Ppk21, both of which cooperatively participate in regulating cell cycle progression, and Cdc25 is involved in this process in fission yeast.

CRISPR Screen Contributes to Novel Target Discovery in Prostate Cancer

Prostate cancer (PCa) is one of the common malignancies in male adults. Recent advances in omics technology, especially in next-generation sequencing, have increased the opportunity to identify genes that correlate with cancer diseases, including PCa. In addition, a genetic screen based on CRISPR/Cas9 technology has elucidated the mechanisms of cancer progression and drug resistance, which in turn has enabled the discovery of new targets as potential genes for new therapeutic targets. In the era of precision medicine, such knowledge is crucial for clinicians in their decision-making regarding patient treatment. In this review, we focus on how CRISPR screen for PCa performed to date has contributed to the identification of biologically critical and clinically relevant target genes.