AMPK Promotes SPOP-Mediated NANOG Degradation to Regulate Prostate Cancer Cell Stemness

Nanog maintains stemness of Lkb1-deficient lung adenocarcinoma and prevents gastric differentiation

Growing evidence supports that LKB1-deficient KRAS-driven lung tumors represent a unique therapeutic challenge, displaying strong cancer plasticity that promotes lineage conversion and drug resistance. Here we find that murine lung tumors from the KrasLSL-G12D/+ ; Lkb1flox/flox (KL) model show strong plasticity, which associates with up-regulation of stem cell pluripotency genes such as Nanog. Deletion of Nanog in KL model initiates a gastric differentiation program and promotes mucinous lung tumor growth. We find that NANOG is not expressed at a meaningful level in human lung adenocarcinoma (ADC), as well as in human lung invasive mucinous adenocarcinoma (IMA). Gastric differentiation involves activation of Notch signaling, and perturbation of Notch pathway by the γ-secretase inhibitor LY-411575 remarkably impairs mucinous tumor formation. In contrast to non-mucinous tumors, mucinous tumors are resistant to phenformin treatment. Such therapeutic resistance could be overcome through combined treatments with LY-411575 and phenformin. Overall, we uncover a previously unappreciated plasticity of LKB1-deficient tumors and identify the Nanog-Notch axis in regulating gastric differentiation, which holds important therapeutic implication for the treatment of mucinous lung cancer.

Cancer Stemness Meets Immunity: From Mechanism to Therapy

Cancer stem cells (CSCs) are self-renewing cells that facilitate tumor initiation, promote metastasis, and enhance cancer therapy resistance. Transcriptomic analyses across many cancer types have revealed a prominent association between stemness and immune signatures, potentially implying a biological interaction between such hallmark features of cancer. Emerging experimental evidence has substantiated the influence of CSCs on immune cells, including tumor-associated macrophages, myeloid-derived suppressor cells, and T cells, in the tumor microenvironment and, reciprocally, the importance of such immune cells in sustaining CSC stemness and its survival niche. This review covers the cellular and molecular mechanisms underlying the symbiotic interactions between CSCs and immune cells and how such heterotypic signaling maintains a tumor-promoting ecosystem and informs therapeutic strategies intercepting this co-dependency.

RNAi mediated silencing of Nanog expression suppresses the growth of human colorectal cancer stem cells

Colorectal cancer (CRC) is the third most common cancer in the world known for its poor recurrence-free prognosis. Previous studies have shown that it is closely linked with cancer stem cells (CSCs), which have self-renewal potential and the capacity to differentiate into diverse populations. Nanog is an important transcription factor that functions to maintain the self-renewal and proliferation of embryonic stem cells; however, many recent studies have shown that Nanog is also highly expressed in many cancer stem cells. To investigate whether Nanog plays a crucial role in maintaining the stemness of colorectal CSCs, RNA interference was used to downregulate Nanog expression in the CRC stem cell line, EpCAM+CD44+HCT-116 cells (CCSCs). We examined the anti-tumor function of Nanog in vitro and in vivo, using small interfering RNA. Our results revealed that the Nanog mRNA expression level in CCSCs was higher than that in HCT-116 cells. We found that the depletion of Nanog inhibited proliferation and promoted apoptosis in CCSCs. In addition, the invasive ability of CCSCs was markedly restricted when Nanog was silenced by small interfering RNA. Furthermore, we found that the silencing of Nanog decreased tumor size and weight and improved the survival rate of tumor-bearing mice. In conclusion, these findings collectively demonstrate that Nanog, which is highly expressed in CRC stem cells, is a key factor in the development of tumor growth, and it may serve as a potential marker of prognosis and a novel and effective therapeutic target for the treatment of CRC.

Pluripotent Stem Cells: Cancer Study, Therapy, and Vaccination

INTRODUCTION

Pluripotent stem cells (PSCs) are promising tools for modern regenerative medicine applications because of their stemness properties, which include unlimited self-renewal and the ability to differentiate into all cell types in the body. Evidence suggests that a rare population of cells within a tumor, termed cancer stem cells (CSCs), exhibit stemness and phenotypic plasticity properties that are primarily responsible for resistance to chemotherapy, radiotherapy, metastasis, cancer development, and tumor relapse. Different therapeutic approaches that target CSCs have been developed for tumor eradication.

RESULTS AND DISCUSSION

In this review, we first provide an overview of different viewpoints about the origin of CSCs. Particular attention has been paid to views believe that CSCs are probably appeared through dysregulation of very small embryonic-like stem cells (VSELs) which reside in various tissues as the main candidate for tissue-specific stem cells. The expression of pluripotency markers in these two types of cells can strengthen the validity of this theory. In this regard, we discuss the common properties of CSCs and PSCs, and highlight the potential of PSCs in cancer studies, therapeutic applications, as well as educating the immune system against CSCs.

CONCLUSION

In conclusion, the resemblance of CSCs to PSCs can provide an appropriate source of CSC-specific antigens through cultivation of PSCs which brings to light promising ideas for prophylactic and therapeutic cancer vaccine development.

AMP-Activated Protein Kinase: Do We Need Activators or Inhibitors to Treat or Prevent Cancer?

AMP-activated protein kinase (AMPK) is a key regulator of cellular energy balance. In response to metabolic stress, it acts to redress energy imbalance through promotion of ATP-generating catabolic processes and inhibition of ATP-consuming processes, including cell growth and proliferation. While findings that AMPK was a downstream effector of the tumour suppressor LKB1 indicated that it might act to repress tumourigenesis, more recent evidence suggests that AMPK can either suppress or promote cancer, depending on the context. Prior to tumourigenesis AMPK may indeed restrain aberrant growth, but once a cancer has arisen, AMPK may instead support survival of the cancer cells by adjusting their rate of growth to match their energy supply, as well as promoting genome stability. The two isoforms of the AMPK catalytic subunit may have distinct functions in human cancers, with the AMPK-α1 gene often being amplified, while the AMPK-α2 gene is more often mutated. The prevalence of metabolic disorders, such as obesity and Type 2 diabetes, has led to the development of a wide range of AMPK-activating drugs. While these might be useful as preventative therapeutics in individuals predisposed to cancer, it seems more likely that AMPK inhibitors, whose development has lagged behind that of activators, would be efficacious for the treatment of pre-existing cancers.

S119N Mutation of the E3 Ubiquitin Ligase SPOP Suppresses SLC7A1 Degradation to Regulate Hepatoblastoma Progression

A previous study on hepatoblastoma revealed novel mutations and cancer genes in the Wnt pathway and ubiquitin ligase complex, including the tumor suppressor speckle-type BTB/POZ (SPOP). Moreover, the SPOP gene affected cell growth, and its S119N mutation was identified as a loss-of-function mutation in hepatoblastoma. This study aimed to explore more functions and the potential mechanism of SPOP and its S119N mutation. The in vitro effects of SPOP on cell proliferation, invasion, apoptosis, and in vivo tumor growth were investigated by western blot analysis, Cell Counting Kit-8, colony formation assay, flow cytometry, and xenograft animal experiments. The substrate of SPOP was discovered by a protein quantification assay and quantitative ubiquitination modification assay. The present study further proved that SPOP functioned as an anti-oncogene through the phosphatidylinositol 3-kinase/Akt signaling pathway to affect various malignant biological behaviors of hepatoblastoma both in vitro and in vivo. Furthermore, experimental results also suggested that solute carrier family 7 member 1 (SLC7A1) might be a substrate of SPOP and influence cell phenotype by regulating arginine metabolism. In conclusion, these findings demonstrated the function of SPOP and revealed a potential substrate related to hepatoblastoma tumorigenesis, which might thus provide a novel therapeutic target for hepatoblastoma.

The oncogenic potential of NANOG: An important cancer induction mediator

Cancer stem cells (CSCs) are a unique population in the tumor, but they only comprise 2%-5% of the tumor bulk. Although CSCs share several features with embryonic stem cells, CSCs can give rise to the tumor cells. CSCs overexpress embryonic transcription factor NANOG, which is downregulated in differentiated tissues. This transcription factor confers CSC's stemness, unlimited self-renewal, metastasis, invasiveness, angiogenesis, and drug-resistance with the assistance of WNT, OCT4, SOX2, Hedgehog, BMI-1, and other complexes. NANOG facilitates CSCs development via multiple pathways, like angiogenesis and lessening E-cadherin expression levels, which paves the road for metastasis. Moreover, NANOG represses apoptosis and leads to drug-resistance. This review aims to highlight the pivotal role of NANOG and the pertained pathways in CSCs. Also, this current study intends to demonstrate that targeting NANOG can dimmish the CSCs, sensitize the tumor to chemotherapy, and eradicate the cancer cells.

Androgen Deprivation Induces Reprogramming of Prostate Cancer Cells to Stem-Like Cells

In the past few years, cell plasticity has emerged as a mode of targeted therapy evasion in prostate adenocarcinoma. When exposed to anticancer therapies, tumor cells may switch into a different histological subtype, such as the neuroendocrine phenotype which is associated with treatment failure and a poor prognosis. In this study, we demonstrated that long-term androgen signal depletion of prostate LNCaP cells induced a neuroendocrine phenotype followed by re-differentiation towards a “stem-like” state. LNCaP cells incubated for 30 days in charcoal-stripped medium or with the androgen receptor antagonist 2-hydroxyflutamide developed neuroendocrine morphology and increased the expression of the neuroendocrine markers βIII-tubulin and neuron specific enolase (NSE). When cells were incubated for 90 days in androgen-depleted medium, they grew as floating spheres and had enhanced expression of the stem cell markers CD133, ALDH1A1, and the transporter ABCB1A. Additionally, the pluripotent transcription factors Nanog and Oct4 and the angiogenic factor VEGF were up-regulated while the expression of E-cadherin was inhibited. Cell viability revealed that those cells were resistant to docetaxel and 2-hidroxyflutamide. Mechanistically, androgen depletion induced the decrease in AMP-activated kinase (AMPK) expression and activation and stabilization of the hypoxia-inducible factor HIF-1α. Overexpression of AMPK in the stem-like cells decreased the expression of stem markers as well as that of HIF-1α and VEGF while it restored the levels of E-cadherin and PGC-1α. Most importantly, docetaxel sensitivity was restored in stem-like AMPK-transfected cells. Our model provides a new regulatory mechanism of prostate cancer plasticity through AMPK that is worth exploring.

PIK3C3 regulates the expansion of liver CSCs and PIK3C3 inhibition counteracts liver cancer stem cell activity induced by PI3K inhibitor

The existence of cancer stem cells (CSCs) accounts for hepatocellular carcinoma (HCC) treatment resistance, relapse, and metastasis. Although the elimination of cancer stem cells is crucial for cancer treatment, strategies for their elimination are limited. Here, we report that a remarkable increase in PIK3C3 was detected in HCC tissues and liver CSCs. Upregulated PIK3C3 facilitated liver CSC expansion in HCC cells; RNA interference-mediated silencing of PIK3C3 had an opposite effect. Furthermore, PIK3C3 inhibition by inhibitors effectively eliminated liver CSCs and inhibited the growth of tumors in vivo. The phosphoinositide 3-kinase (PI3K) pathway is considered an important hallmark of cancer. One of our recent studies found that prolonged inhibition by inhibitors of class I PI3K induces liver CSCs expansion. To our surprise, PIK3C3 inhibition blocked the expansion of CSCs induced by PI3K inhibitor; moreover, treatment with the combination of PIK3C3 inhibitor and PI3K inhibitor in maximal suppresses the expansion of liver CSCs of tumors in mice. Mechanistically, inhibition of PIK3C3 inhibit the activation of SGK3, a CSCs promoter, induced by PI3K inhibitor. We also show that PIK3C3 inhibitor suppresses liver CSCs by activation of the AMP-activated kinase (AMPK). Although PIK3C3 plays a critical role in autophagy, we find that PIK3C3 regulates liver CSCs independent of the autophagy process. These findings uncover the effective suppression of liver CSCs by targeting PIK3C3, and targeting PIK3C3 in combination with PI3K inhibitor inhibits the expansion of liver CSCs efficiently, which is an attractive therapeutic regimen for the treatment of HCC.

TGF-β signaling regulates SPOP expression and promotes prostate cancer cell stemness

SPOP, a substrate binding adaptor of E3 ubiquitin ligase Cullin3, is frequently mutated in human prostate cancer (PCa). However, whether and how SPOP is regulated at transcriptional level in PCa remain unclear. Here, we report that SPOP is down-regulated in PCa stem-like cells (CSCs) and tissues. Our study reveals that SPOP expression is repressed by TGF-β / SMAD signaling axis in PCa CSCs. SPOP promoter contains SMAD-binding elements (SBEs), which can interact with SMAD3. Moreover, TGF-β signaling inhibitor SB431542 promotes the SPOP expression and abrogates PCa stemness. Clinically, SPOP expression is downregulated in PCa patients, which is significantly related to a poor prognosis and lower survival rate. Thus, our findings uncover a mechanism of how SPOP expression is mediated in PCa CSCs via TGF-β/ SMAD3 signaling.

SPOP and cancer: a systematic review

The initiation and progression of cancer is dependent on the acquisition of mutations in oncogenes or tumor suppressor genes that ultimately leads to the dysregulation of key regulatory pathways. Though these mutations often occur in direct regulators of such pathways, some may confer tumorigenic potential by indirectly targeting several pathways congruently thereby exerting pleiotropic effects. In recent years, the tumor suppressor gene Speckle Type POZ Protein (SPOP) has gained a lot of attention as it has been found to be altered in a variety of different cancers. SPOP appears to exert pleiotropic tumorigenic effects as multiple different regulatory pathways become dysregulated upon SPOP alterations. SPOP has been identified as an E3 ubiquitin ligase substrate binding subunit of the proteasome complex. Since protein degradation is critical in regulating proper cellular function it is not surprising that the proteasome pathway is often found to be disrupted in cancer. Many studies have now indicated that mutations or changes in the expression of SPOP are one of several underlying reasons of proteasome pathway disruption in different cancers. Ultimately, either SPOP downregulation or mutation promotes stabilization of direct SPOP targets which subsequently promotes cancer through the dysregulation of key regulatory pathways. In this review, we will discuss the current literature on cancer-specific SPOP alterations as well the SPOP targets that are stabilized, and the pathways that are dysregulated, as a result.

The role of ubiquitination in tumorigenesis and targeted drug discovery

Ubiquitination, an important type of protein posttranslational modification (PTM), plays a crucial role in controlling substrate degradation and subsequently mediates the "quantity" and "quality" of various proteins, serving to ensure cell homeostasis and guarantee life activities. The regulation of ubiquitination is multifaceted and works not only at the transcriptional and posttranslational levels (phosphorylation, acetylation, methylation, etc.) but also at the protein level (activators or repressors). When regulatory mechanisms are aberrant, the altered biological processes may subsequently induce serious human diseases, especially various types of cancer. In tumorigenesis, the altered biological processes involve tumor metabolism, the immunological tumor microenvironment (TME), cancer stem cell (CSC) stemness and so on. With regard to tumor metabolism, the ubiquitination of some key proteins such as RagA, mTOR, PTEN, AKT, c-Myc and P53 significantly regulates the activity of the mTORC1, AMPK and PTEN-AKT signaling pathways. In addition, ubiquitination in the TLR, RLR and STING-dependent signaling pathways also modulates the TME. Moreover, the ubiquitination of core stem cell regulator triplets (Nanog, Oct4 and Sox2) and members of the Wnt and Hippo-YAP signaling pathways participates in the maintenance of CSC stemness. Based on the altered components, including the proteasome, E3 ligases, E1, E2 and deubiquitinases (DUBs), many molecular targeted drugs have been developed to combat cancer. Among them, small molecule inhibitors targeting the proteasome, such as bortezomib, carfilzomib, oprozomib and ixazomib, have achieved tangible success. In addition, MLN7243 and MLN4924 (targeting the E1 enzyme), Leucettamol A and CC0651 (targeting the E2 enzyme), nutlin and MI-219 (targeting the E3 enzyme), and compounds G5 and F6 (targeting DUB activity) have also shown potential in preclinical cancer treatment. In this review, we summarize the latest progress in understanding the substrates for ubiquitination and their special functions in tumor metabolism regulation, TME modulation and CSC stemness maintenance. Moreover, potential therapeutic targets for cancer are reviewed, as are the therapeutic effects of targeted drugs.

Targeting cancer stem cell pathways for cancer therapy

Since cancer stem cells (CSCs) were first identified in leukemia in 1994, they have been considered promising therapeutic targets for cancer therapy. These cells have self-renewal capacity and differentiation potential and contribute to multiple tumor malignancies, such as recurrence, metastasis, heterogeneity, multidrug resistance, and radiation resistance. The biological activities of CSCs are regulated by several pluripotent transcription factors, such as OCT4, Sox2, Nanog, KLF4, and MYC. In addition, many intracellular signaling pathways, such as Wnt, NF-κB (nuclear factor-κB), Notch, Hedgehog, JAK-STAT (Janus kinase/signal transducers and activators of transcription), PI3K/AKT/mTOR (phosphoinositide 3-kinase/AKT/mammalian target of rapamycin), TGF (transforming growth factor)/SMAD, and PPAR (peroxisome proliferator-activated receptor), as well as extracellular factors, such as vascular niches, hypoxia, tumor-associated macrophages, cancer-associated fibroblasts, cancer-associated mesenchymal stem cells, extracellular matrix, and exosomes, have been shown to be very important regulators of CSCs. Molecules, vaccines, antibodies, and CAR-T (chimeric antigen receptor T cell) cells have been developed to specifically target CSCs, and some of these factors are already undergoing clinical trials. This review summarizes the characterization and identification of CSCs, depicts major factors and pathways that regulate CSC development, and discusses potential targeted therapy for CSCs.

Regulation of Stem Cells by Cullin-RING Ligase

Stem cells can remain quiescent, self-renewal, and differentiate into many types of cells and even cancer stem cells. The coordination of these complex processes maintains the homeostasis of the organism. Ubiquitination is an important posttranslational modification process that regulates protein stability and activity. The ubiquitination levels of stem cell-associated proteins are closely related with stem cell characteristics. Cullin-RING Ligases (CRLs) are the largest family of E3 ubiquitin ligases, accounting for approximately 20% of proteins degraded by proteasome. In this review, we discuss the role of CRLs in stem cell homeostasis, self-renewal, and differentiation and expound their ubiquitination substrates. In addition, we also discuss the effect of CRLs on the formation of cancer stem cells that may provide promising therapy strategies for cancer.

Cullin 3 and Its Role in Tumorigenesis

Cullin 3 (Cul3) family of ubiquitin ligases comprises three components, the RING finger protein RBX1, the Cul3 scaffold, and a Bric-a-brac/Tramtrack/Broad complex (BTB) protein. The BTB protein serves as a bridge to connect Cul3 to substrate and is functionally equivalent to the combination of substrate adaptor and linker in other Cullin complexes. Human genome encodes for ~180 BTB proteins, implying a broad spectrum of ubiquitination signals and substrate repertoire. Accordingly, Cul3 ubiquitin ligases are involved in diverse cellular processes, including cell division, differentiation, cytoskeleton remodeling, stress responses, and nerve cell functions. Emerging evidence has pointed to the prominent role of Cul3 ubiquitin ligases in cancer. This chapter will describe recent advances on the roles of Cul3 E3 ligase complexes in regulating various cancer hallmarks and therapeutic responses and the mutation/dysregulation of Cul3 substrate adaptors in cancer. In particular, we will focus on several extensively studied substrate adaptors, such as Keap1, SPOP, KLHL20, and LZTR1, and will also discuss other recently identified Cul3 adaptors with oncogenic or tumor-suppressive functions. We conclude that Cul3 ubiquitin ligases represent master regulators of human malignancies and highlight the importance of developing modulating agents for oncogenic/tumor-suppressive Cul3 E3 ligase complexes to prevent or intervene tumorigenesis.

DAXX in cancer: phenomena, processes, mechanisms and regulation

DAXX displays complex biological functions. Remarkably, DAXX overexpression is a common feature in diverse cancers, which correlates with tumorigenesis, disease progression and treatment resistance. Structurally, DAXX is modular with an N-terminal helical bundle, a docking site for many DAXX interactors (e.g. p53 and ATRX). DAXX's central region folds with the H3.3/H4 dimer, providing a H3.3-specific chaperoning function. DAXX has two functionally critical SUMO-interacting motifs. These modules are connected by disordered regions. DAXX's structural features provide a framework for deciphering how DAXX mechanistically imparts its functions and how its activity is regulated. DAXX modulates transcription through binding to transcription factors, epigenetic modifiers, and chromatin remodelers. DAXX's localization in the PML nuclear bodies also plays roles in transcriptional regulation. DAXX-regulated genes are likely important effectors of its biological functions. Deposition of H3.3 and its interactions with epigenetic modifiers are likely key events for DAXX to regulate transcription, DNA repair, and viral infection. Interactions between DAXX and its partners directly impact apoptosis and cell signaling. DAXX's activity is regulated by posttranslational modifications and ubiquitin-dependent degradation. Notably, the tumor suppressor SPOP promotes DAXX degradation in phase-separated droplets. We summarize here our current understanding of DAXX's complex functions with a focus on how it promotes oncogenesis.

Prostate Cancer-associated SPOP mutations enhance cancer cell survival and docetaxel resistance by upregulating Caprin1-dependent stress granule assembly

BACKGROUND

The gene encoding the E3 ubiquitin ligase substrate-binding adaptor SPOP is frequently mutated in primary prostate cancer, but how SPOP mutations contribute to prostate cancer pathogenesis remains poorly understood. Stress granules (SG) assembly is an evolutionarily conserved strategy for survival of cells under stress, and often upregulated in human cancers. We investigated the role of SPOP mutations in aberrant activation of the SG in prostate cancer and explored the relevanve of the mechanism in therapy resistance.

METHODS

We identified SG nucleating protein Caprin1 as a SPOP interactor by using the yeast two hybrid methods. A series of functional analyses in cell lines, patient samples, and xenograft models were performed to investigate the biological significance and clinical relevance of SPOP regulation of SG signaling in prostate cancer.

RESULTS

The cytoplasmic form of wild-type (WT) SPOP recognizes and triggers ubiquitin-dependent degradation of Caprin1. Caprin1 abundance is elevated in SPOP-mutant expressing prostate cancer cell lines and patient specimens. SPOP WT suppresses SG assembly, while the prostate cancer-associated mutants enhance SG assembly in a Caprin1-dependent manner. Knockout of SPOP or expression of prostate cancer-associated SPOP mutants conferred resistance to death caused by SG inducers (e.g. docetaxel, sodium arsenite and H2O2) in prostate cancer cells.

CONCLUSIONS

SG assembly is aberrantly elevated in SPOP-mutated prostate cancer. SPOP mutations cause resistance to cellular stress induced by chemtherapeutic drug such as docetaxel in prostate cancer.

SPOP suppresses pancreatic cancer progression by promoting the degradation of NANOG

Speckle-type POZ domain protein (SPOP), an adaptor in the E3 ubiquitin ligase complex, recognizes substrates and promotes protein degradation via the ubiquitin-proteasome system. It appears to help regulate progression of several cancers, and we show here that it acts as a tumor suppressor in pancreatic cancer. Our analysis of patient tissues showed decreased SPOP expression, which was associated with poor prognosis. SPOP knockdown in SW1990 (in vitro/vivo) and PANC-1 (in vitro) cells led to significantly greater proliferation, migration, and invasion. Co-immunoprecipitation experiments in SW1990 cells showed that SPOP interacted with the stem-cell marker NANOG, and this interaction has recently been shown to play a critical role in regulating progression of prostate cancer. We showed that, in one patient with pancreatic cancer, the expression of a truncated form of SPOP (p.Q360*) lacking the nuclear localization signal led to nuclear accumulation of NANOG, which promoted growth and metastasis of pancreatic cancer cells. Our results suggest that SPOP suppresses progression of pancreatic cancer by promoting the ubiquitination and subsequent degradation of NANOG. These results identify the SPOP-NANOG interaction as a potential therapeutic target against pancreatic cancer.

Network Pharmacology Identifies the Mechanisms of Action of Shaoyao Gancao Decoction in the Treatment of Osteoarthritis

BACKGROUND Osteoarthritis (OA) affects the health and wellbeing of the elderly. Shaoyao Gancao decoction (SGD) is used in traditional Chinese medicine (TCM) for the treatment of OA and has two active components, shaoyao (SY) and gancao (GC). This study aimed to undertake a network pharmacology analysis of the mechanism of the effects of SGD in OA. MATERIAL AND METHODS The active compounds and candidates of SGD were obtained from the Traditional Chinese Medicine (TCM) Databases@Taiwan, the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database, the STITCH database, the ChEMBL database, and PubChem. The network pharmacology approach involved network construction, target prediction, and module analysis. Significant signaling pathways of the cluster networks for SGD and OA were identified using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. RESULTS Twenty-three bioactive compounds were identified, corresponding to 226 targets for SGD. Also, 187 genes were closely associated with OA, of which 161 overlapped with the targets of SGD and were considered to be therapeutically relevant. Functional enrichment analysis suggested that SGD exerted its pharmacological effects in OA by modulating multiple pathways, including cell cycle, cell apoptosis, drug metabolism, inflammation, and immune modulation. CONCLUSIONS A novel approach was developed to systematically identify the mechanisms of the TCM, SGD in OA using network pharmacology analysis.

Cellular and Molecular Mechanisms Underlying Prostate Cancer Development: Therapeutic Implications

Prostate cancer is the most frequent nonskin cancer and second most common cause of cancer-related deaths in man. Prostate cancer is a clinically heterogeneous disease with many patients exhibiting an aggressive disease with progression, metastasis, and other patients showing an indolent disease with low tendency to progression. Three stages of development of human prostate tumors have been identified: intraepithelial neoplasia, adenocarcinoma androgen-dependent, and adenocarcinoma androgen-independent or castration-resistant. Advances in molecular technologies have provided a very rapid progress in our understanding of the genomic events responsible for the initial development and progression of prostate cancer. These studies have shown that prostate cancer genome displays a relatively low mutation rate compared with other cancers and few chromosomal loss or gains. The ensemble of these molecular studies has led to suggest the existence of two main molecular groups of prostate cancers: one characterized by the presence of ERG rearrangements (~50% of prostate cancers harbor recurrent gene fusions involving ETS transcription factors, fusing the 5' untranslated region of the androgen-regulated gene TMPRSS2 to nearly the coding sequence of the ETS family transcription factor ERG) and features of chemoplexy (complex gene rearrangements developing from a coordinated and simultaneous molecular event), and a second one characterized by the absence of ERG rearrangements and by the frequent mutations in the E3 ubiquitin ligase adapter SPOP and/or deletion of CDH1, a chromatin remodeling factor, and interchromosomal rearrangements and SPOP mutations are early events during prostate cancer development. During disease progression, genomic and epigenomic abnormalities accrued and converged on prostate cancer pathways, leading to a highly heterogeneous transcriptomic landscape, characterized by a hyperactive androgen receptor signaling axis.

The Contributions of Prostate Cancer Stem Cells in Prostate Cancer Initiation and Metastasis

Research in the last decade has clearly revealed a critical role of prostate cancer stem cells (PCSCs) in prostate cancer (PC). Prostate stem cells (PSCs) reside in both basal and luminal layers, and are the target cells of oncogenic transformation, suggesting a role of PCSCs in PC initiation. Mutations in PTEN, TP53, and RB1 commonly occur in PC, particularly in metastasis and castration-resistant PC. The loss of PTEN together with Ras activation induces partial epithelial–mesenchymal transition (EMT), which is a major mechanism that confers plasticity to cancer stem cells (CSCs) and PCSCs, which contributes to metastasis. While PTEN inactivation leads to PC, it is not sufficient for metastasis, the loss of PTEN concurrently with the inactivation of both TP53 and RB1 empower lineage plasticity in PC cells, which substantially promotes PC metastasis and the conversion to PC adenocarcinoma to neuroendocrine PC (NEPC), demonstrating the essential function of TP53 and RB1 in the suppression of PCSCs. TP53 and RB1 suppress lineage plasticity through the inhibition of SOX2 expression. In this review, we will discuss the current evidence supporting a major role of PCSCs in PC initiation and metastasis, as well as the underlying mechanisms regulating PCSCs. These discussions will be developed along with the cancer stem cell (CSC) knowledge in other cancer types.