Upregulation of CASP9 through NF-κB and Its Target MiR-1276 Contributed to TNFα-promoted Apoptosis of Cancer Cells Induced by Doxorubicin

Under some conditions, nuclear factor-κB (NF-κB) has a pro-apoptotic role, but the mechanisms underlying this function remain unclear. This study demonstrated that NF-κB directly binds to CASP9 and miR1276 in tumor necrosis factor α (TNFα)-treated HeLa and HepG2 cells. NF-κB upregulated CASP9 expression, whereas downregulated miR1276 expression in the TNFα-treated cells. The miR1276 repressed CASP9 expression in both cells. As a result, a typical NF-κB-mediated coherent feed-forward loop was formed in the TNFα-treated cells. It was proposed that the NF-κB-mediated loop may contribute to cell apoptosis under certain conditions. This opinion was supported by the following evidence: TNFα promoted the apoptosis of HeLa and HepG2 cells induced by doxorubicin (DOX). CASP9 was significantly upregulated and activated by TNFα in the DOX-induced cells. Moreover, a known inhibitor of CASP9 activation significantly repressed the TNFα promotion of apoptosis induced by DOX. These findings indicate that CASP9 is a new mediator of the NF-κB pro-apoptotic pathway, at least in such conditions. This study therefore provides new insights into the pro-apoptotic role of NF-κB. The results also shed new light on the molecular mechanism underlying TNFα-promotion of cancer cells apoptosis induced by some anticancer drugs such as DOX.

A lysosome specific theranostic NO donor inhibits cancer cells by stimuli responsive molecular self-decomposition with an on-demand fluorescence pattern

The anticancer mechanism of NO is difficult to study owing to its short lifetime and high reactivity. Thus, a theranostic anticancer NO donor assembled with NO on-demand release abilities, accurate lysosome location capabilities and signal feedback behavior was developed. Profiting from the theranostic properties, the specific mechanism was comprehensively studied. Spectral and cell imaging studies revealed that the as prepared NO donors could release NO in solution or within cancer cells. Fluorescence co-dyeing experiments demonstrated that Mo-Nap-NO entered lysosomes specifically and disrupted them after being triggered by light. Upon irradiation with 460 nm visible light, both the donors demonstrated considerable in vitro anticancer effects. A further mechanistic study showed that after entering the lysosome and being triggered by 460 nm irradiation, NO ruptured the lysosome, resulting in the release of cathepsin D into the cytosol, which activated the caspase3 mediated apoptosis pathway.

LYG-202 inhibits activation of endothelial cells and angiogenesis through CXCL12/CXCR7 pathway in breast cancer

Angiogenesis is critical for the growth and metastasis of triple-negative breast cancer (TNBC) and its inhibition reduces the risk of progression of metastatic TNBC. In this study, we investigated that LYG-202, a flavonoid with a piperazine substitution, inhibited angiogenesis induced by conditioned media (CM) from MDA-MB-231 cells under hypoxia and revealed its underlying mechanism. The results showed that LYG-202 decreased CXCL12 secretion and CXCR7 expression, leading to suppression of its downstream ERK/AKT/nuclear factor kappa B (NF-κB) signaling, which eventually decreased the expression of MMP-2, MMP-9, RhoA and increased VE-cadherin expression in EA.hy 926 cells treated with CM from MDA-MB-231 cells under hypoxia. The decreased migration ability, increased cell adhesion and inhibited CXCR7 pathway by LYG-202 could also be reproduced in human umbilical vein endothelial cells. More importantly, LYG-202 also inhibited tumor angiogenesis and tumor growth of human breast cancer MDA-MB-231 cells in nude mice through CXCL12/CXCR7 pathway. In summary, LYG-202 is a potential agent to prohibit tumor angiogenesis through inhibiting the activation of endothelial cells.

Combination of 7-hydroxycoumarin in a platinum(IV) complex derived from cisplatin enhanced cytotoxicity with multiple mechanisms of action

A novel compound, Cou-platin, composed of 7-hydroxycoumarin and a platinum(IV) moiety derived from cisplatin was designed and synthesized. Significantly, Cou-platin exhibited more potent in vitro antitumor activity against all tested cancer cell lines than that of cisplatin, which was mainly attributed to the liberation of cisplatin and 7-hydroxycoumarin upon reduction with a biomolecular agent. Besides, cellular accumulation of Cou-platin was dramatically increased among several cancer cells in contrast to cisplatin. Flow cytometry study revealed that Cou-platin arrested cell cycle at G2 phase and induced cell apoptosis. Western blots results indicated that it not only activated cell apoptosis pathway, but also inhibited extracellular regulated protein kinases/mitogen-activated protein kinase pathway. In vivo tests showed that Cou-platin, at equimolar dose to cisplatin, could inhibit tumor growth in nude mouse HCT116 tumor xenograft models almost as cisplatin and oxaliplatin, but with less toxicity.

Hybrid of DNA-targeting Chlorambucil with Pt(IV) Species to Reverse Drug Resistance

Two hybrids of Pt(IV) species were designed and prepared by addition of a chlorambucil unit to the axial positions of the Pt(IV) complexes derived from DN603 and DN604. In vitro studies of two hybrids against two pairs of cisplatin sensitive and resistant cancer cell lines indicated that compound 5 had superior antitumor activity to cisplatin and chlorambucil via suppressing DNA damage repair to reverse drug resistance. Mechanistic investigation suggested that the potent antitumor activity of compound 5 arose from its major suppression of CK2-mediated MRE11-RAD50-NBS1(MRN) complex promotion of DNA double-strand break (DSB) repair. In nude mice with A549/CDDP xenografts, compound 5 exhibited higher anticancer efficacy than cisplatin and chlorambucil by reversing drug resistance, displayed improved effectiveness, and had no toxicity effects. Overall, compound 5 is a promising drug candidate, which could promote the anticancer activity and reverse drug resistance by attenuating CK2-induced MRN-dependent DSB repair.

Identification of novel NF-κB transcriptional targets in TNFα-treated HeLa and HepG2 cells

Identification of target genes of NF-κB is critical for deeply understanding its biological functions. Here, we identified five novel NF-κB target genes. Firstly, we found that 20 NF-κB potential target genes (PTGs) identified by ChIP-Seq and Genechip assay were enriched into the KEGG term of Pathways in cancer, 16 of them were enriched into the KEGG pathways of small cell lung cancer, chronic myeloid leukemia, basal cell carcinoma, pancreatic cancer, and colorectal cancer. Among these PTGs, there are many documented NF-κB target genes. Therefore, NF-κB may play important role in cancer progression by transcriptionally regulating these genes. Apart from the known target genes, we also found some novel PTGs including CYCS, MITF, FZD1, FZD8, and PIAS1. We subsequently demonstrated whether NF-κB transcriptionally control the five PTGs. The ChIP-Seq assay revealed that NF-κB/p65 bound to these genes in TNFα-treated HeLa. The bioinformatic analysis indicated that the NF-κB binding regions (i.e., ChIP-Seq peaks) contained κB sites and NF-κB/RelA DNA-binding motif. The ChIP-qPCR assay also confirmed that NF-κB bound to these regions in both TNFα-treated HeLa and HepG2 cells. The reporter construct showed that NF-κB could regulate luciferase expression via its binding region. Finally, qPCR and Western blot assay demonstrated that NF-κB indeed regulated the expression of these genes in the TNFα-treated HeLa and HepG2 cells. In a word, CYCS, MITF, FZD1, FZD8, and PIAS1 were identified as bona fide NF-κB target genes. These findings provide more insights into the role of NF-κB in cancers.

Reversal of cisplatin resistance in human gastric cancer cells by a wogonin-conjugated Pt(IV) prodrug via attenuating Casein Kinase 2-mediated Nuclear Factor-κB pathways

Pt(IV) prodrugs, with two additional coordination sites in contrast to Pt(II) drugs, have been actively studied nowadays, for they can perform well in enhancing the accumulation and retention of the corresponding Pt(II) drugs in cancer cells. Our designed Pt(II) drug, DN604, was recently found to exhibit significant anticancer activity and low toxicity, while, wogonin, a naturally O-methylated flavones, has been widely investigated for its tumor therapeutic potential. Thus, two Pt(IV)-based prodrugs were derived by addition of a wogonin unit to the axial position of DN604 and its analogue DN603 via a linker group. In vitro cytotoxicity assay indicated that the resulting compound 8 not only inherited the genotoxicity of DN604 on gastric cancer cells, but also obtained the COX inhibitory property arising from wogonin. Further studies revealed that compound 8 caused the accumulation of ROS production and decreased the mitochondrial membrane potential (ΔΨm). The CK2α kinase activity assay, ChIP and luciferase assays showed that CK2 plays an important role in the blockade of compound 8 on activated NF-κB survival pathways, which were established for sensitivity of cancer cells to platinum drugs. Similarly in vivo, in nude mice with SGC-7901/cDDP xenografts, compound 8 improved the effectiveness of DN604 via reversing tumor resistance and maintaining low toxicity. Overall, compound 8 is a promising Pt(IV) prodrug, which could be used to promote the anticancer activity of its counterpart Pt(II) species and reverse drug resistance via attenuating CK2-mediated NF-κB pathways during platinum-based chemotherapies.