Camptothecin induces G2/M phase arrest through the ATM-Chk2-Cdc25C axis as a result of autophagy-induced cytoprotection: Implications of reactive oxygen species

Downstream-of-gene (DoG) transcripts contribute to an imbalance in the cancer cell transcriptome

Downstream-of-gene (DoG) transcripts are an emerging class of noncoding RNAs. However, it remains largely unknown how DoG RNA production is regulated and whether alterations in DoG RNA signatures exist in major cancers. Here, through transcriptomic analyses of matched tumors and nonneoplastic tissues and cancer cell lines, we reveal a comprehensive catalog of DoG RNA signatures. Through separate lines of evidence, we support the biological importance of DoG RNAs in carcinogenesis. First, we show tissue-specific and stage-specific differential expression of DoG RNAs in tumors versus paired normal tissues with their respective host genes involved in tumor-promoting versus tumor-suppressor pathways. Second, we identify that differential DoG RNA expression is associated with poor patient survival. Third, we identify that DoG RNA induction is a consequence of treating colon cancer cells with the topoisomerase I (TOP1) poison camptothecin and following TOP1 depletion. Our results underlie the significance of DoG RNAs and TOP1-dependent regulation of DoG RNAs in diversifying and modulating the cancer transcriptome.

The impact of selective HDAC inhibitors on the transcriptome of early mouse embryos

BACKGROUND

Histone acetylation, which is regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs), plays a crucial role in the control of gene expression. HDAC inhibitors (HDACi) have shown potential in cancer therapy; however, the specific roles of HDACs in early embryos remain unclear. Moreover, although some pan-HDACi have been used to maintain cellular undifferentiated states in early embryos, the specific mechanisms underlying their effects remain unknown. Thus, there remains a significant knowledge gap regarding the application of selective HDACi in early embryos.

RESULTS

To address this gap, we treated early embryos with two selective HDACi (MGCD0103 and T247). Subsequently, we collected and analyzed their transcriptome data at different developmental stages. Our findings unveiled a significant effect of HDACi treatment during the crucial 2-cell stage of zygotes, leading to a delay in embryonic development after T247 and an arrest at 2-cell stage after MGCD0103 administration. Furthermore, we elucidated the regulatory targets underlying this arrested embryonic development, which pinpointed the G2/M phase as the potential period of embryonic development arrest caused by MGCD0103. Moreover, our investigation provided a comprehensive profile of the biological processes that are affected by HDACi, with their main effects being predominantly localized in four aspects of zygotic gene activation (ZGA): RNA splicing, cell cycle regulation, autophagy, and transcription factor regulation. By exploring the transcriptional regulation and epigenetic features of the genes affected by HDACi, we made inferences regarding the potential main pathways via which HDACs affect gene expression in early embryos. Notably, Hdac7 exhibited a distinct response, highlighting its potential as a key player in early embryonic development.

CONCLUSIONS

Our study conducted a comprehensive analysis of the effects of HDACi on early embryonic development at the transcriptional level. The results demonstrated that HDACi significantly affected ZGA in embryos, elucidated the distinct actions of various selective HDACi, and identified specific biological pathways and mechanisms via which these inhibitors modulated early embryonic development.

MAGED2 Depletion Promotes Stress-Induced Autophagy by Impairing the cAMP/PKA Pathway

Melanoma-associated antigen D2 (MAGED2) plays an essential role in activating the cAMP/PKA pathway under hypoxic conditions, which is crucial for stimulating renal salt reabsorption and thus explaining the transient variant of Bartter's syndrome. The cAMP/PKA pathway is also known to regulate autophagy, a lysosomal degradation process induced by cellular stress. Previous studies showed that two members of the melanoma-associated antigens MAGE-family inhibit autophagy. To explore the potential role of MAGED2 in stress-induced autophagy, specific MAGED2-siRNA were used in HEK293 cells under physical hypoxia and oxidative stress (cobalt chloride, hypoxia mimetic). Depletion of MAGED2 resulted in reduced p62 levels and upregulation of both the autophagy-related genes (ATG5 and ATG12) as well as the autophagosome marker LC3II compared to control siRNA. The increase in the autophagy markers in MAGED2-depleted cells was further confirmed by leupeptin-based assay which concurred with the highest LC3II accumulation. Likewise, under hypoxia, immunofluorescence in HEK293, HeLa and U2OS cell lines demonstrated a pronounced accumulation of LC3B puncta upon MAGED2 depletion. Moreover, LC3B puncta were absent in human fetal control kidneys but markedly expressed in a fetal kidney from a MAGED2-deficient subject. Induction of autophagy with both physical hypoxia and oxidative stress suggests a potentially general role of MAGED2 under stress conditions. Various other cellular stressors (brefeldin A, tunicamycin, 2-deoxy-D-glucose, and camptothecin) were analyzed, which all induced autophagy in the absence of MAGED2. Forskolin (FSK) inhibited, whereas GNAS Knockdown induced autophagy under hypoxia. In contrast to other MAGE proteins, MAGED2 has an inhibitory role on autophagy only under stress conditions. Hence, a prominent role of MAGED2 in the regulation of autophagy under stress conditions is evident, which may also contribute to impaired fetal renal salt reabsorption by promoting autophagy of salt-transporters in patients with MAGED2 mutation.

Effectiveness of Nonfunctionalized Graphene Oxide Nanolayers as Nanomedicine against Colon, Cervical, and Breast Cancer Cells

Recent studies in nanomedicine have intensively explored the prospective applications of surface-tailored graphene oxide (GO) as anticancer entity. However, the efficacy of nonfunctionalized graphene oxide nanolayers (GRO-NLs) as an anticancer agent is less explored. In this study, we report the synthesis of GRO-NLs and their in vitro anticancer potential in breast (MCF-7), colon (HT-29), and cervical (HeLa) cancer cells. GRO-NLs-treated HT-29, HeLa, and MCF-7 cells showed cytotoxicity in the MTT and NRU assays via defects in mitochondrial functions and lysosomal activity. HT-29, HeLa, and MCF-7 cells treated with GRO-NLs exhibited substantial elevations in ROS, disturbances of the mitochondrial membrane potential, an influx of Ca²⁺, and apoptosis. The qPCR quantification showed the upregulation of caspase 3, caspase 9, bax, and SOD1 genes in GRO-NLs-treated cells. Western blotting showed the depletion of P21, P53, and CDC25C proteins in the above cancer cell lines after GRO-NLs treatment, indicating its function as a mutagen to induce mutation in the P53 gene, thereby affecting P53 protein and downstream effectors P21 and CDC25C. In addition, there may be a mechanism other than P53 mutation that controls P53 dysfunction. We conclude that nonfunctionalized GRO-NLs exhibit prospective biomedical application as a putative anticancer entity against colon, cervical, and breast cancers.

Combination of Chemotherapy and Mild Hyperthermia Using Targeted Nanoparticles: A Potential Treatment Modality for Breast Cancer

Despite the clinical benefits that chemotherapeutics has had on the treatment of breast cancer, drug resistance remains one of the main obstacles to curative cancer therapy. Nanomedicines allow therapeutics to be more targeted and effective, resulting in enhanced treatment success, reduced side effects, and the possibility of minimising drug resistance by the co-delivery of therapeutic agents. Porous silicon nanoparticles (pSiNPs) have been established as efficient vectors for drug delivery. Their high surface area makes them an ideal carrier for the administration of multiple therapeutics, providing the means to apply multiple attacks to the tumour. Moreover, immobilising targeting ligands on the pSiNP surface helps direct them selectively to cancer cells, thereby reducing harm to normal tissues. Here, we engineered breast cancer-targeted pSiNPs co-loaded with an anticancer drug and gold nanoclusters (AuNCs). AuNCs have the capacity to induce hyperthermia when exposed to a radiofrequency field. Using monolayer and 3D cell cultures, we demonstrate that the cell-killing efficacy of combined hyperthermia and chemotherapy via targeted pSiNPs is 1.5-fold higher than applying monotherapy and 3.5-fold higher compared to using a nontargeted system with combined therapeutics. The results not only demonstrate targeted pSiNPs as a successful nanocarrier for combination therapy but also confirm it as a versatile platform with the potential to be used for personalised medicine.

Camptothecin Effectively Regulates Germline Differentiation through Bam-Cyclin A Axis in Drosophila melanogaster

Camptothecin (CPT), first isolated from Chinese tree Camptotheca acuminate, produces rapid and prolonged inhibition of DNA synthesis and induction of DNA damage by targeting topoisomerase I (top1), which is highly activated in cancer cells. CPT thus exhibits remarkable anticancer activities in various cancer types, and is a promising therapeutic agent for the treatment of cancers. However, it remains to be uncovered underlying its cytotoxicity toward germ cells. In this study we found that CPT, a cell cycle-specific anticancer agent, reduced fecundity and exhibited significant cytotoxicity toward GSCs and two-cell cysts. We showed that CPT induced GSC loss and retarded two-cell cysts differentiation in a niche- or apoptosis-independent manner. Instead, CPT induced ectopic expression of a differentiation factor, bag of marbles (Bam), and regulated the expression of cyclin A, which contributed to GSC loss. In addition, CPT compromised two-cell cysts differentiation by decreasing the expression of Bam and inducing cell arrest at G1/S phase via cyclin A, eventually resulting in two-cell accumulation. Collectively, this study demonstrates, for the first time in vivo, that the Bam-cyclin A axis is involved in CPT-mediated germline stem cell loss and two-cell cysts differentiation defects via inducing cell cycle arrest, which could provide information underlying toxicological effects of CPT in the productive system, and feature its potential to develop as a pharmacology-based germline stem cell regulation agent.

Downregulation of CDC25C in NPCs Disturbed Cortical Neurogenesis

Cell division regulators play a vital role in neural progenitor cell (NPC) proliferation and differentiation. Cell division cycle 25C (CDC25C) is a member of the CDC25 family of phosphatases which positively regulate cell division by activating cyclin-dependent protein kinases (CDKs). However, mice with the Cdc25c gene knocked out were shown to be viable and lacked the apparent phenotype due to genetic compensation by Cdc25a and/or Cdc25b. Here, we investigate the function of Cdc25c in developing rat brains by knocking down Cdc25c in NPCs using in utero electroporation. Our results indicate that Cdc25c plays an essential role in maintaining the proliferative state of NPCs during cortical development. The knockdown of Cdc25c causes early cell cycle exit and the premature differentiation of NPCs. Our study uncovers a novel role of CDC25C in NPC division and cell fate determination. In addition, our study presents a functional approach to studying the role of genes, which elicit genetic compensation with knockout, in cortical neurogenesis by knocking down in vivo.

Dual-Functionalized Nanoliposomes Achieve a Synergistic Chemo-Phototherapeutic Effect

The enhancement of photodynamic therapy (PDT) effectiveness by combining it with other treatment modalities and improved drug delivery has become an interesting field in cancer research. We have prepared and characterized nanoliposomes containing the chemotherapeutic drug irinotecan (CPT11_lip), the photodynamic agent protoporphyrin IX (PpIX_lip), or their combination (CPT11-PpIX_lip). The effects of individual and bimodal (chemo-phototherapeutic) treatments on HeLa cells have been studied by a combination of biological and photophysical studies. Bimodal treatments show synergistic cytotoxic effects on HeLa cells at relatively low doses of PpIX/PDT and CPT11. Mechanistic cell inactivation studies revealed mitotic catastrophe, apoptosis, and senescence contributions. The enhanced anticancer activity is due to a sustained generation of reactive oxygen species, which increases the number of double-strand DNA breaks. Bimodal chemo-phototherapeutic liposomes may have a very promising future in oncological therapy, potentially allowing a reduction in the CPT11 concentration required to achieve a therapeutic effect and overcoming resistance to individual cancer treatments.

RYBP Sensitizes Cancer Cells to PARP Inhibitors by Regulating ATM Activity

Ring1 and YY1 Binding Protein (RYBP) is a member of the non-canonical polycomb repressive complex 1 (PRC1), and like other PRC1 members, it is best described as a transcriptional regulator. Previously, we showed that RYBP, along with other PRC1 members, is also involved in the DNA damage response. RYBP inhibits recruitment of breast cancer gene 1(BRCA1) complex to DNA damage sites through its binding to K63-linked ubiquitin chains. In addition, ataxia telangiectasia mutated (ATM) kinase serves as an important sensor kinase in early stages of DNA damage response. Here, we report that overexpression of RYBP results in inhibition in both ATM activity and recruitment to DNA damage sites. Cells expressing RYBP show less phosphorylation of the ATM substrate, Chk2, after DNA damage. Due to its ability to inhibit ATM activity, we find that RYBP sensitizes cancer cells to poly-ADP-ribose polymerase (PARP) inhibitors. Although we find a synergistic effect between PARP inhibitor and ATM inhibitor in cancer cells, this synergy is lost in cells expressing RYBP. We also show that overexpression of RYBP hinders cancer cell migration through, at least in part, ATM inhibition. We provide new mechanism(s) by which RYBP expression may sensitize cancer cells to DNA damaging agents and inhibits cancer metastasis.

The Distinct Roles of LKB1 and AMPK in p53-Dependent Apoptosis Induced by Cisplatin

Liver kinase B1 (LKB1) is a serine/threonine protein kinase that acts as a key tumor suppressor protein by activating its downstream kinases, such as AMP-activated protein kinase (AMPK). However, the regulatory actions of LKB1 and AMPK on DNA damage response (DDR) remain to be explored. In this study, we investigated the function of LKB1 in DDR induced by cisplatin, a representative DNA-damaging agent, and found that LKB1 stabilizes and activates p53 through the c-Jun N-terminal kinase (JNK) pathway, which promotes cisplatin-induced apoptosis in human fibrosarcoma cell line HT1080. On the other hand, we found that AMPKα1 and α2 double knockout (DKO) cells showed enhanced stabilization of p53 and increased susceptibility to apoptosis induced by cisplatin, suggesting that AMPK negatively regulates cisplatin-induced apoptosis. Moreover, the additional stabilization of p53 and subsequent apoptosis in AMPK DKO cells were clearly canceled by the treatment with the antioxidants, raising the possibility that AMPK suppresses the p53 activation mediated by oxidative stress. Thus, our findings unexpectedly demonstrate the reciprocal regulation of p53 by LKB1 and AMPK in DDR, which provides insights into the molecular mechanisms of DDR.

A silica-based antioxidant nanoparticle for oral delivery of Camptothecin which reduces intestinal side effects while improving drug efficacy for colon cancer treatment

Camptothecin (CPT) is a potent anticancer agent for the treatment of colorectal cancer; however, it exhibits some limitations, including poor solubility, low stability, and low bioavailability via oral administration, which restrict its usability in clinical treatments. In addition, overproduction of reactive oxygen species (ROS) during chemotherapy induces drug resistance and severe intestinal side effects. In this study, silica-installed ROS scavenging nanoparticles (siRNP) with 50-60 nm in diameter were employed to overcome the aforementioned drawbacks of CPT. The solubility of CPT was significantly improved by incorporating it into the core of the nanoparticle, forming CPT-loaded siRNP (CPT@siRNP). The anticancer activity of CPT@siRNP against colorectal cancer cells (C-26) in vitro was significantly improved as compared to free CPT through higher efficiency of intracellular internalization and induction of apoptosis. Owing to its antioxidant properties, CPT@siRNP reduced cytotoxicity to normal endothelial cells, which was in sharp contrast to the high toxicity of free CPT. Oral administration of CPT and CPT@siRNP to the C-26 tumor-bearing mice exhibited antitumor activity, accompanied by effective suppression of tumor growth. Although CPT treatment suppressed tumor progression, it caused severe side effects, including intestinal damage and significant bodyweight loss. Interestingly, such noticeable side effects were not observed in the mice treated with CPT@siRNP, and the effect of tumor growth inhibition tended to be similar to or higher than that of CPT treatment. The results obtained in this study indicate that CPT@siRNP is a potential therapeutic nanomedicine for the treatment of colon cancer. STATEMENT OF SIGNIFICANCE: Here we employed silica-containing antioxidant nanoparticle (siRNP) as promising oral delivery nanocarrier of campothecin (CPT) to treat colon cancer. The design of siRNP via covalent conjugation of antioxidant nitroxide radicals and the silanol groups in the polymer backbone contributes to a significant increase in the absorption of hydrophobic drug molecules inside the core and enhances the stability of nanoparticles in the gastrointestinal environment for oral drug delivery. CPT-loaded siRNP (CPT@siRNP) significantly improved solubility of CPT. As compared to free CTP, the CPT@siRNP treatment showed a significantly higher toxicity to colon cancer cell, inhibition of cancer cell migration, and induction of apopotosis. With the antioxidant feature, siRNP also significantly suppressed the intestinal side effects caused by CPT treatment in tumor-bearing mouse model.

eIF3a-PPP2R5A-mediated ATM/ATR dephosphorylation is essential for irinotecan-induced DNA damage response

Objectives

The individual differences and pervasive resistance seriously hinder the optimization of irinotecan‐based therapeutic effectiveness. Eukaryotic translation initiation factor 3a (eIF3a) plays a key role in tumour occurrence, prognosis and therapeutic response. This study focused on the role of eIF3a in irinotecan‐induced DNA damage response.

Materials and Methods

The cck8 cell viability and clone survival analyses were used to test the regulatory role of eIF3a on irinotecan sensitivity in HT29 and CACO2 cell lines in vitro. This regulatory role was also verified in vivo by conducting subcutaneous xenograft model. Irinotecan‐induced DNA damage, cell cycle arrest and apoptosis were tested by flow cytometry analysis, TUNEL staining, western blot and comet assays. The immunofluorescence, co‐IP, luciferase reporter assay, RIP and flow cytometric analyses were carried out to investigate the underline mechanism.

Results

We demonstrated that eIF3a continuously activates ATM/ATR signal by translationally inhibiting PPP2R5A, a phosphatase that directly dephosphorylates and inactivates ATM/ATR after DNA repair complete. Suppression of PPP2R5A resulted in chronic ATM/ATR phosphorylation and activation, impairing DNA repair and enhancing irinotecan sensitivity.

Conclusions

Our study suggested eIF3a with a high potential to influence phenotypic functions, which may contribute substantially to the early identification of susceptible individuals and the provision of personalized medication to irinotecan‐treated patients.

Peroxidasin Enhances Basal Phenotype and Inhibits Branching Morphogenesis in Breast Epithelial Progenitor Cell Line D492

The human breast is composed of terminal duct lobular units (TDLUs) that are surrounded by stroma. In the TDLUs, basement membrane separates the stroma from the epithelial compartment, which is divided into an inner layer of luminal epithelial cells and an outer layer of myoepithelial cells. Stem cells and progenitor cells also reside within the epithelium and drive a continuous cycle of gland remodelling that occurs throughout the reproductive period. D492 is an epithelial cell line originally isolated from the stem cell population of the breast and generates both luminal and myoepithelial cells in culture. When D492 cells are embedded into 3D reconstituted basement membrane matrix (3D-rBM) they form branching colonies mimicking the TDLUs of the breast, thereby providing a well-suited in vitro model for studies on branching morphogenesis and breast development. Peroxidasin (PXDN) is a heme-containing peroxidase that crosslinks collagen IV with the formation of sulfilimine bonds. Previous studies indicate that PXDN plays an integral role in basement membrane stabilisation by crosslinking collagen IV and as such contributes to epithelial integrity. Although PXDN has been linked to fibrosis and cancer in some organs there is limited information on its role in development, including in the breast. In this study, we demonstrate expression of PXDN in breast epithelium and stroma and apply the D492 cell line to investigate the role of PXDN in cell differentiation and branching morphogenesis in the human breast. Overexpression of PXDN induced basal phenotype in D492 cells, loss of plasticity and inhibition of epithelial-to-mesenchymal transition as is displayed by complete inhibition of branching morphogenesis in 3D culture. This is supported by results from RNA-sequencing which show significant enrichment in genes involved in epithelial differentiation along with significant negative enrichment of EMT factors. Taken together, we provide evidence for a novel role of PXDN in breast epithelial differentiation and mammary gland development.

Natural products are an important source for proteasome regulating agents

BACKGROUND

Natural medicines have a long history in the prevention and treatment of various diseases in East Asian region, especially in China. Modern research has proved that the pharmacological effects of numerous natural medicines involve the participation of ubiquitin proteasome system (UPS). UPS can degrade the unwanted and damaged proteins widely distributed in the nucleus and cytoplasm of various eukaryotes.

PURPOSE

The objective of the present study was to review and discuss the regulatory effects of natural products and extracts on proteasome components, which may help to find new proteasome regulators for drug development and clinical applications.

METHODS

The related information was compiled using the major scientific databases, such as CNKI, Elsevier, ScienceDirect, PubMed, SpringerLink, Wiley Online, and GeenMedical. The keywords "natural product" and "proteasome" were applied to extract the literature. Nature derived extracts, compounds and their derivatives involved in proteasome regulation were included, and the publications related to synthetic proteasome agents were excluded.

RESULTS

The pharmacological effects of more than 80 natural products and extracts derived from phytomedicines related to the proteasome regulation were reviewed. These natural products were classified according to their chemical properties. We also summarized some laws of action of natural products as proteasome regulators in the treatment of diseases, and listed the action characteristics of the typical natural products.

CONCLUSION

Natural products derived from nature can induce the degradation of damaged proteins through UPS or act as regulators to directly regulate the activity of proteasome. But few proteasome modulators are applied clinically. Summary of known rules for proteasome modulators will contribute to discover, modify and synthesize more proteasome modulators for clinical applications.

ATM at the crossroads of reactive oxygen species and autophagy

Reactive oxygen species (ROS) are generally small, short-lived and highly reactive molecules, initially thought to be a pathological role in the cell. A growing amount of evidence in recent years argues for ROS functioning as a signaling intermediate to facilitate cellular adaptation in response to pathophysiological stress through the regulation of autophagy. Autophagy is an essential cellular process that plays a crucial role in recycling cellular components and damaged organelles to eliminate sources of ROS in response to various stress conditions. A large number of studies have shown that DNA damage response (DDR) transducer ataxia-telangiectasia mutated (ATM) protein can also be activated by ROS, and its downstream signaling pathway is involved in autophagy regulation. This review aims at providing novel insight into the regulatory mechanism of ATM activated by ROS and its molecular basis for inducing autophagy, and revealing a new function that ATM can not only maintain genome homeostasis in the nucleus, but also as a ROS sensor trigger autophagy to maintain cellular homeostasis in the cytoplasm.

Camptothecin Inhibits Neddylation to Activate the Protective Autophagy Through NF-κB/AMPK/mTOR/ULK1 Axis in Human Esophageal Cancer Cells

The neddylation pathway is overactivated in esophageal cancer. Our previous studies indicated that inactivation of neddylation by the NAE inhibitor induced apoptosis and autophagy in cancer cells. Camptothecin (CPT), a well-known anticancer agent, could induce apoptosis and autophagy in cancer cells. However, whether CPT could affect the neddylation pathway and the molecular mechanisms of CPT-induced autophagy in esophageal cancer remains elusive. We found that CPT induced apoptosis and autophagy in esophageal cancer. Mechanistically, CPT inhibited the activity of neddylation and induced the accumulation of p-IkBa to block NF-κB pathway. Furthermore, CPT induced the generation of ROS to modulate the AMPK/mTOR/ULK1 axis to finally promote protective autophagy. In our study, we elucidate a novel mechanism of the NF-κB/AMPK/mTOR/ULK1 pathway in CPT-induced protective autophagy in esophageal cancer cells, which provides a sound rationale for combinational anti-ESCC therapy with CPT and inhibition AMPK/ULK1 pathway.

Current advances of endophytes as a platform for production of anti-cancer drug camptothecin

Camptothecin (CPT), a well-known monoterpenoid indole alkaloid with broad-spectrum anti-cancer activity, is produced from plants and endophytes. In view of the limitations of plants as sources of camptothecin in productivity and efficiency, endophytes serve as the fast growth, high cost-effectiveness, good reproducibility, and feasible genetic manipulation, so they have the potential to meet the huge market demand of the pharmaceutical industry. In this review, we summarized the isolation, identification and fermentation of CPT-producing endophytes, as well as the biosynthesis, extraction and detection of camptothecin from endophytes. Among them, we put emphasis on increasing the production of camptothecin in endophytes through different strategies such as changing the proportion of carbon, nitrogen and phosphate source, adding the precursors, elicitors or adsorbent resin, utilizing co-culture fermentation or fermenter culture. However, cell subculture and metabolic reprogramming affect the expression of camptothecin biosynthetic genes in CPT-producing endophytes, which poses a challenge to the industrial production of camptothecin. Therefore, it will be useful to gain insights through the review of these researches and provide alternative approaches to develop economical, eco-friendly and reliable natural products.

Label-Free Quantification of Cell Cycle Synchronicity of Human Neural Progenitor Cells Based on Electrophysiology Phenotypes

The ability to coax human-induced pluripotent stem cells (hiPSCs) into human neural progenitor cells (hNPCs) can lead to novel drug discovery and transplant therapy platforms for neurological diseases. Since hNPCs can form organoids that mimic brain development, there is emerging interest in their label-free characterization for controlling cell composition to optimize organoid formation in three-dimensional (3D) cultures. However, this requires the ability to quantify hNPCs in heterogeneous samples with subpopulations of similar phenotype. Using high-throughput (>6000 cells per condition), single-cell impedance cytometry, we present the utilization of electrophysiology for quantification of hNPC subpopulations that are altered in cell cycle synchronicity by camptothecin (CPT) exposure. Electrophysiology phenotypes are determined from impedance magnitude and phase metrics for distinguishing each cell cycle phase, as validated by flow cytometry, for a wide range of subpopulation proportions. Using multishell dielectric models for each cell cycle phase, electrophysiology alterations with CPT dose could be predicted. This label-free detection strategy can prevent loss of cell viability to speed the optimization of cellular compositions for organoid development.

Analyzing Signaling Pathways Using Antibody Arrays

Cell signaling is comprised of complex networks that regulate homeostasis and human diseases. The analyses of such pathways would improve our understanding of disease pathology and direct drug development. However, it remains a great challenge to study pathways using traditional methods. We developed a high-throughput sandwich-based antibody array technology for the simultaneous detection of multiple targets, capable of identifying the relative expression levels or phosphorylation levels of major signaling pathway proteins. This array-based system features a nitrocellulose membrane or glass slide solid support, spotted with antibodies targeting key proteins of major signaling pathways, including RTK, EGFR, MAPK, AKT, apoptosis, TGFb, JAK/STAT, NFkB, and insulin receptor pathways. We employed these antibody arrays to investigate how the anti-cancer drugs, camptothecin and phorbol 12-myristate 13-acetate (PMA), alter protein phosphorylation in Jurkat and HeLa cells, respectively. Our array data suggest that camptothecin treatment induced DNA double-strand breaks in Jurkat cells and activated the DNA damage pathways ATM and Chk2, which then further induced apoptosis through caspase 3 and PARP. PMA induced the MAPK pathway in HeLa cells through the activation of ERK, CREB, and RSK1. These array results are consistent with previous studies using traditional methods and were validated with Western blotting. Our studies demonstrate that pathway antibody arrays provide a rapid, efficient, and multiplexed approach for profiling phosphorylated proteins.

Vitamin D3 Ameliorates DNA Damage Caused by Developmental Exposure to Endocrine Disruptors in the Uterine Myometrial Stem Cells of Eker Rats

Early-life exposure of the myometrium to endocrine-disrupting chemicals (EDCs) has been shown to increase the risk of uterine fibroid (UF) prevalence in adulthood. Vitamin D3 (VitD3) is an unique, natural compound that may reduce the risk of developing UFs. However, little is known about the role and molecular mechanism of VitD3 on exposed myometrial stem cells (MMSCs). We investigated the role and molecular mechanism underlying VitD3 action on DNA damage response (DDR) defects in rat MMSCs due to developmental exposure to diethylstilbestrol (DES), with the additional goal of understanding how VitD3 decreases the incidence of UFs later in life. Female newborn Eker rats were exposed to DES or a vehicle early in life; they were then sacrificed at 5 months of age (pro-fibroid stage) and subjected to myometrial Stro1+/CD44+ stem cell isolation. Several techniques were performed to determine the effect of VitD3 treatment on the DNA repair pathway in DES-exposed MMSCs (DES-MMSCs). Results showed that there was a significantly reduced expression of RAD50 and MRE11, key DNA repair proteins in DES-exposed myometrial tissues, compared to vehicle (VEH)-exposed tissues (p < 0.01). VitD3 treatment significantly decreased the DNA damage levels in DES-MMSCs. Concomitantly, the levels of key DNA damage repair members, including the MRN complex, increased in DES-MMSCs following treatment with VitD3 (p < 0.01). VitD3 acts on DNA repair via the MRN complex/ATM axis, restores the DNA repair signaling network, and enhances DDR. This study demonstrates, for the first time, that VitD3 treatment attenuated the DNA damage load in MMSCs exposed to DES and classic DNA damage inducers. Moreover, VitD3 targets primed MMSCs, suggesting a novel therapeutic approach for the prevention of UF development.

The role of CDC25C in cell cycle regulation and clinical cancer therapy: a systematic review

One of the most prominent features of tumor cells is uncontrolled cell proliferation caused by an abnormal cell cycle, and the abnormal expression of cell cycle-related proteins gives tumor cells their invasive, metastatic, drug-resistance, and anti-apoptotic abilities. Recently, an increasing number of cell cycle-associated proteins have become the candidate biomarkers for early diagnosis of malignant tumors and potential targets for cancer therapies. As an important cell cycle regulatory protein, Cell Division Cycle 25C (CDC25C) participates in regulating G2/M progression and in mediating DNA damage repair. CDC25C is a cyclin of the specific phosphatase family that activates the cyclin B1/CDK1 complex in cells for entering mitosis and regulates G2/M progression and plays an important role in checkpoint protein regulation in case of DNA damage, which can ensure accurate DNA information transmission to the daughter cells. The regulation of CDC25C in the cell cycle is affected by multiple signaling pathways, such as cyclin B1/CDK1, PLK1/Aurora A, ATR/CHK1, ATM/CHK2, CHK2/ERK, Wee1/Myt1, p53/Pin1, and ASK1/JNK-/38. Recently, it has evident that changes in the expression of CDC25C are closely related to tumorigenesis and tumor development and can be used as a potential target for cancer treatment. This review summarizes the role of CDC25C phosphatase in regulating cell cycle. Based on the role of CDC25 family proteins in the development of tumors, it will become a hot target for a new generation of cancer treatments.

A Multifunctional Nanotherapy for Targeted Treatment of Colon Cancer by Simultaneously Regulating Tumor Microenvironment

Colitis-associated colon cancer (CAC) is a widely recognized cancer, while treatment with the existing chemotherapeutic drugs affords limited clinical benefits. Herein we proposed a site-specific, combination nanotherapy strategy for targeted treatment of CAC by the oral route. Methods: A reactive oxygen species (ROS)-responsive and hydrogen peroxide-eliminating material OCD was synthesized, which was further produced into a functional nanoparticle (OCD NP). The antioxidative stress and anti-inflammatory effects of OCD NP were examined by in vitro and in vivo experiments. By packaging an anticancer drug camptothecin-11 (CPT-11) into OCD NP, a ROS-responsive nanotherapy CPT-11/OCD NP was obtained, and its antitumor activity was evaluated by both in vitro and in vivo studies. Preliminary safety studies were also performed for CPT-11/OCD NP in mice. Results: OCD NP significantly attenuated oxidative stress and inhibited inflammatory response in different cells and mice with induced colitis. CPT-11/OCD NP could selectively release drug molecules under intestinal pH conditions and at high levels of ROS. In C26 murine colon carcinoma cells, this nanotherapy showed significantly higher antitumor activity compared to free CPT-11 and a non-responsive CPT-11 nanotherapy. Correspondingly, oral delivery of CPT-11/OCD NP notably inhibited tumorigenesis and tumor growth in mice with induced CAC. By combination therapy with the nanovehicle OCD NP in the inflammatory phase, more desirable therapeutic effects were achieved. Furthermore, CPT-11/OCD NP displayed excellent safety profile for oral administration at a dose that is 87.3-fold higher than that employed in therapeutic studies. Conclusions: Anticancer nanotherapies derived from intrinsic anti-inflammatory nanocarriers are promising for targeted combination treatment of inflammation-associated tumors by simultaneously shaping pro-inflammatory microenvironment toward a relatively normal niche sensitive to chemotherapy.

Camptothecin induces c-Myc- and Sp1-mediated hTERT expression in LNCaP cells: Involvement of reactive oxygen species and PI3K/Akt

Camptothecin (CPT), a quinoline alkaloid isolated from Camptotheca acuminate, targets topoisomerase I, which is continuously expressed in cancer cells. However, the molecular mechanisms responsible for CPT-induced telomerase inhibition remain unclear. Unexpectedly, we found that CPT upregulates hTERT expression and concomitantly increases telomerase activity. However, transfection of hTERT-targeting siRNA had no effect on CPT-induced G₂/M phase arrest, suggesting that CPT-induced telomerase activation was not related to G₂/M phase arrest. CPT simultaneously increased Nrf2 expression and the level of intracellular reactive oxygen species (ROS), whereas pretreatment with the antioxidants N-acetyl-cysteine (NAC) or glutathione (GSH) strongly attenuated ROS production, which was accompanied by hTERT downregulation. Additionally, transient Nrf2 knockdown enhanced CPT-induced ROS production and hTERT promoter activity. CPT also upregulated hTERT expression and telomerase activity by inducing c-Myc and Sp1 expression and activity. Moreover, c-Myc stimulated ROS production in response to CPT, leading to Sp1 activation, which promoted hTERT expression and telomerase activity. CPT treatment enhanced the phosphorylation of PI3K and Akt, which led to hTERT phosphorylation into the nucleus. These findings demonstrate that CPT positively regulates telomerase activity by upregulating hTERT expression and phosphorylation via the c-Myc/ROS/Sp1 and PI3K/Akt axis.

Camptothecin enhances c-Myc-mediated endoplasmic reticulum stress and leads to autophagy by activating Ca2+-mediated AMPK

Camptothecin (CPT) from Camptotheca acuminate was discovered for anticancer drugs, which targets topoisomease I. However, whether CPT regulates c-Myc expression has not been understood in endoplasmic reticulum (ER) stress and autophagy. In this study, we found that CPT enhanced c-Myc expression and that the transient knockdown of c-Myc abrogated reactive oxygen species (ROS) generation, which resulted in the accumulation of ER stress-regulating proteins, such as PERK, eIF2α, ATF4, and CHOP. Moreover, the transfection of eIF2α-targeted siRNA attenuated CPT-induced autophagy and decreased the levels of Beclin-1 and Atg7, which indicated that CPT upregulated ER stress-mediated autophagy. In addition, CPT phosphorylated AMPK in response to intracellular Ca²⁺ release. Ca²⁺ chelators, ethylene glycol tetraacetic acid and a CaMKII inhibitor, K252a, decreased CPT-induced Beclin-1 and Atg7, and downregulated AMPK phosphorylation, which suggested that CPT-induced Ca²⁺ release leads to the activation of autophagy through CaMKII-mediated AMPK phosphorylation. CPT also phosphorylated JNK and activated the DNA-binding activity of AP-1; furthermore, knockdown of JNK abolished the expression level of Beclin-1 and Atg7, which implied that the JNK-AP-1 pathway was a potent mediator of CPT-induced autophagy. Our findings indicated that CPT promoted c-Myc-mediated ER stress and ROS generation, which enhances autophagy via the Ca²⁺-AMPK and JNK-AP-1 pathways.