B1, a novel naphthalimide-based DNA intercalator, induces cell cycle arrest and apoptosis in HeLa cells via p53 activation

Suppression of oxidative phosphorylation and IDH2 sensitizes colorectal cancer to a naphthalimide derivative and mitoxantrone

Colorectal cancer (CRC) is one of the most prevalent cancers worldwide. Oxidative phosphorylation (OXPHOS) has attracted a considerable attention in CRC. It is of great interest to explore novel therapies that inhibit OXPHOS for CRC treatment. Compound 6c is a novel naphthalimide derivative. However, the effects of 6c on CRC and the underlying mechanism are unclear. In this study, 6c suppressed CRC tumor growth and metastasis. RNA-seq data showed that 6c triggered the inhibition of OXPHOS and tricarboxylic acid cycle. 6c specifically inhibited mitochondrial complex III activity and the expression of isocitrate dehydrogenase 2 (IDH2), resulting in oxidative stress. Antioxidants reversed 6c-induced cell death, senescence, and autophagosomes formation. 6c inhibited autophagy flux; however, pretreatment with autophagy inhibitors resulted in the reduction of 6c-induced cytoplasmic vacuolization and proliferation inhibition. Moreover, combinatory treatment of 6c and mitoxantrone (MIT) showed stronger inhibitory effects on CRC compared with the single agent. Downregulation of IDH2 induced reactive oxygen species production, leading to MIT accumulation and autophagic cell death after co-treatment with 6c and MIT. In summary, our findings indicated 6c as a promising candidate for CRC treatment.

Promising Anticancer Effect of Aurisin A Against the Human Lung Cancer A549 Cell Line

Objective:

To investigate the anticancer effect of aurisin A and the underlying mechanisms of its action on the human lung cancer A549 cell line.

Methods:

Cell viability was determined by sulforhodamine B (SRB) assay, while cell cycle distribution and apoptosis were measured by flow cytometry. The molecular underlying mechanisms of anti-cancer properties of aurisin A was determined by western blot analysis.

Results:

Aurisin A exerts its anticancer effects by inhibiting cell growth (p<0.001), increasing the proportion of cells at the G0/G1 phase (p<0.001), and decreasing the expression of cyclin D (p<0.05) and cyclin-dependent kinase 4 (Cdk-4) (p<0.001). Nuclear morphological changes were observed in aurisin A-treated cells, demonstrated by a dose-dependent increase in the number of apoptosis cells (p<0.001). After aurisin A treatment, B-cell lymphoma 2 (Bcl-2) was down-regulated (p<0.05), cleaved caspase-3 was up-regulated (p<0.05). In addition, aurisin A inhibits migration of cancer cells in a dose-dependent manner (p<0.001) and decreases the expression of epidermal growth factor receptor (EGFR) (p<0.05) and phosphorylated p38 (pp38) (p<0.05).

Conclusion:

These results indicated that in-vitro treatment of aurisin A against this human lung cancer cell line inhibits cell proliferation and migration, and induces apoptosis and cell-cycle arrest. Aurisin A is a promising anticancer agent for use against human lung cancer.

Caspase-independence and characterization of bisnaphthalimidopropyl spermidine induced cytotoxicity in HL60 cells

Bisnaphthalimides are DNA intercalators of potential use as chemotherapeutics but for which the range of mechanism of action is only gradually being elucidated. Using human promyelocytic HL-60 cells, we extend characterization of the cytotoxicity of bisnaphthalimidopropylspermidine (BNIPSpd) and examine the relationship with caspase-activity. Within 4 h exposure, BNIPSpd (1-10 μM) induced significant DNA strand breakage. Evidence of apoptosis was progressive through the experimental period. Within 6 h, BNIPSpd increased the proportion of cells exhibiting plasma membrane phosphatidylserine exposure. Within 12 h, active caspase expression increased and was sustained with 5 and 10 μM BNIPSpd. Flow cytometric analysis revealed caspase activity in cells with and without damaged membranes. By 24 h, 5 and 10 μM BNIPSpd increased hypodiploid DNA content and internucleosomal DNA fragmentation (DNA ladders) typical of the later stages of apoptosis. 1 μM BNIPSpd exposure also increased hypodiploid DNA content by 48 h. Polyamine levels decreased by 24 h BNIPSpd exposure. The pan-caspase inhibitor, z-VAD-fmk, significantly decreased DNA degradation (hypodiploid DNA and DNA ladders) and cytotoxicity. Despite this, cell growth and viability remained significantly impaired. We propose that BNIPSpd cytotoxicity arises through DNA damage and not polyamine depletion and that cytotoxicity is dominated by but not dependent upon caspase driven apoptosis.

A novel triazolonaphthalimide induces apoptosis and inhibits tumor growth by targeting DNA and DNA-associated processes

DNA and DNA-associated processes have been classes of the most important targets of chemotherapeutic drugs. As classic DNA intercalators and topoisomerase inhibitors, naphthalimides have been extensively investigated as potential anti-cancer drugs. We recently synthesized a novel series of triazolonaphthalimides with excellent anti-cancer activities. In the present study, one of the most potent triazolonaphthalimides, LSS-11, was investigated. LSS-11 bound to DNA in vitro and in cell mainly by minor groove binding and significantly increased the stability of DNA, which could be fundamental for the biological activities of LSS-11. In addition to inhibiting DNA topoisomerase II-catalyzed decatenation of knotted circulated DNA, LSS-11 dramatically inhibited DNA replication mediated by polymerase chain reaction and isothermal helicase-dependent amplification, as well as the expression of luciferase driven by a minimal TA promoter in cell. Furthermore, LSS-11 exhibited strong cytotoxicity in selected human colon cancer cell lines by inducing cell cycle arrest and apoptosis, which was accompanied by DNA damage response. Finally, LSS-11 potently inhibited the growth of S180 murine sarcoma and SW480 human colorectal cancer xenografts in vivo without significant major toxicities. These results suggest that LSS-11 deserves further research and development as a novel anti-cancer agent, and provided new understandings of mechanisms by which LSS-11 inhibited multiple DNA-associated processes and tumor growth.

Lnc-ATB contributes to gastric cancer growth through a MiR-141-3p/TGFβ2 feedback loop

The long noncoding RNA (lncRNA) ATB is an important regulator in human tumors. Here, we aimed to investigate the potential molecular mechanisms of lnc-ATB in gastric cancer (GC) tumorigenesis. RT-qPCR analysis was used to detect lnc-ATB expression level in 20 pairs of gastric cancer tissues and adjacent normal gastric mucosa tissues (ANTs). Moreover, the biological role of lnc-ATB was determined in vitro. We found that lnc-ATB was significantly upregulated in GC tissues compared to lnc-ATB expression in ANTs. These high lnc-ATB expression levels predicted poor prognosis in GC patients. Low levels of lnc-ATB inhibited GC cell proliferation and cell cycle arrest in vitro. Lnc-ATB was found to directly bind miR-141-3p. Moreover, TGF-β actives lnc-ATB and TGF-β2 directly binds mir-141-3p. Finally, we demonstrated that lnc-ATB fulfilled its oncogenic roles in a ceRNA-mediated manner. Our study suggests that lnc-ATB promotes tumor progression by interacting with miR-141-3p and that Lnc-ATB may be a valuable prognostic predictor for GC. In conclusion, the positive feedback loop of lnc-ATB/miR-141-3p/TGF-β2 may be a potential therapeutic target for the treatment of GC.

Antitumor effect of forbesione isolated from Garcinia hanburyi on cholangiocarcinoma in vitro and in vivo

Cholangiocarcinoma (CCA) is a malignancy with no effective therapy and poor prognosis. Forbesione, a caged xanthone isolated from Garcinia hanburyi, has been reported to inhibit proliferation and to induce apoptosis in human CCA cell lines. The present study aimed to further explore the potential anticancer properties of forbesione by testing its effects against the hamster CCA cell line Ham-1 in vitro and in vivo. It was observed that forbesione inhibited the growth of Ham-1 cells in vitro and suppressed Ham-1 growth as allograft in hamsters by inducing cell cycle arrest at the S phase. This was mediated by decreasing the protein expression of cyclin E, cyclin A and cyclin-dependent kinase 2. In addition, increased expression of p21 and p27 was detected, which could possibly explain the reduced expression of proliferating cell nuclear antigen and of the bile duct cell marker cytokeratin 19 observed in forbesione-treated Ham-1 cells in vitro and in tumor tissues of forbesione-treated hamsters. Furthermore, forbesione induced apoptosis through multiple pathways. The death receptor pathway was activated by increased expression of Fas, Fas-associated death domain and activated caspase-3, along with decreased expression of procaspase-8 and procaspase-3. The mitochondrial pathway was driven by increased expression of B-cell lymphoma (Bcl)-2-like protein 4, activated caspase-9 and inhibitor of κB-α, along with decreased expression of Bcl-2, survivin, procaspase-9 and nuclear factor-κB/p65. The endoplasmic reticulum pathway was stimulated by increased expression of activated caspase-12 and decreased expression of procaspase-12. No side effects or toxicity were observed in forbesione-treated hamsters. Thus, forbesione is a potential drug candidate for cancer therapy that deserves further investigation.

New role of aminothiazonaphthalimide derivatives: outstanding photoinitiators for cationic and radical photopolymerizations under visible LEDs

Aminothiazonaphthalimide derivatives can act as photoinitiators (when combined with additives) to start the cationic polymerization or the radical polymerization upon exposure to visible LEDs or a polychromatic visible light.

E2F1-dependent pathways are involved in amonafide analogue 7-d-induced DNA damage, G2/M arrest, and apoptosis in p53-deficient K562 cells

The E2F1 gene well known is its pivotal role in regulating the entry from G1 to S phase, while the salvage antitumoral pathway which implicates it, especially in the absence of p53, is not fully characterized. We therefore attempted to identify the up- and down-stream events involved in the activation of the E2F1-dependent pro-apoptotic pathway. For this purpose, a amonafide analogue, 7-d (2-(3-(2-(Dimethylamino)ethylamino)propyl)-6-(dodecylamino)-1H-benzo[de]isoquinoline-1,3(2H)-dione) was screened, which exhibited high antitumor activity against p53-deficient human Chronic Myelogenous Leukemia (CML) K562 cells. Analysis of flow cytometry and western blots of K562 cells treated with 7-d revealed an appreciable G2/M cycle arrest and apoptosis in a dose and time-dependent manner via p53-independent pathway. A striking increase in "Comet tail" formation and γ-H2AX expression showed that DNA double strand breaks (DSB) were caused by 7-d treatment. ATM/ATR signaling was reported to connect E2F1 induction with apoptosis in response to DNA damage. Indeed, 7-d-induced G2/M arrest and apoptosis were antagonized by ATM/ATR signaling inhibitor, Caffeine, which suggested that ATM/ATR signaling was activated by 7-d treatment. Furthermore, the increased expression of E2F1, p73, and Apaf-1 and p73 dissociation from HDM2 was induced by 7-d treatment, however, knockout of E2F1 expression reversed p73, Apaf-1, and p21(Cip1/WAF1) expression, reactivated cell cycle progression, and inhibited 7-d-induced apoptosis. Altogether our results for the first time indicate that 7-d mediates its growth inhibitory effects on CML p53-deficient cells via the activation of an E2F1-dependent mitochondrial and cell cycle checkpoint signaling pathway which subsequently targets p73, Apaf-1, and p21(Cip1/WAF1).

B1-induced caspase-independent apoptosis in MCF-7 cells is mediated by down-regulation of Bcl-2 via p53 binding to P2 promoter TATA box

The Bcl-2 family contains a panel of proteins which are conserved regulators of apoptosis in mammalian cells, like the anti-apoptotic protein Bcl-2. According to its significant role in altering susceptibility to apoptosis, the deciphering of the mechanism of Bcl-2 expression modulation may be crucial for identifying therapeutics strategies for cancer. Treatment with naphthalimide-based DNA intercalators, including M2-A and R16, generally leads to a decrease in Bcl-2 intracellular amounts. Whereas the interest for these chemotherapeutics is accompanied by advances in the fundamental understanding of their anticancer properties, the molecular mechanism underlying changes in Bcl-2 expression remains poorly understood. We report here that p53 contributes to Bcl-2 down-regulation induced by B1, a novel naphthalimide-based DNA intercalating agent. Indeed, the decrease in Bcl-2 protein levels observed during B1-induced apoptosis was correlated to the decrease in mRNA levels, as a result of the inhibition of Bcl-2 transcription and promoter activity. In this context, we evaluated p53 contribution in the Bcl-2 transcriptional down-regulation. We found a significant increase of p53 binding to P(2) promoter TATA box in MCF7 cells by chromatin immunoprecipitation. These data suggest that B1-induced caspase-independent apoptosis in MCF-7 cells is associated with the activation of p53 and the down-regulation of Bcl-2. Our study strengthens the links between p53 and Bcl-2 at a transcriptional level, upon naphthalimide-based DNA intercalator treatment.