Cytotoxicity, crosslinking and biological activity of three mitomycins

Stereoisomeric mitomycins interstrand crosslinks differently impact gene expression in MCF-7 and K562 cancer cells

Mitomycin C (MC) is an anticancer drug used to treat stomach, anal and lung cancers. The main cytotoxicity of MC is due to its ability to form interstrand crosslinks with DNA (ICLs). The stereochemical configuration at C1″ of MC major ICL is R (α-ICL). In contrast, decarbamoylmitomycin C, a synthetic derivative of MC, generates the major S stereoisomeric ICL (β-ICL). Here, we investigated the effect of the stereochemical configuration of the α/β-ICL on the cellular response by focusing on gene expression changes in MCF-7 and K562 cell lines, one with wild type and the other with mutated TP53, upon treatment with both ICLs. We transfected both cell lines with duplex oligonucleotides containing either the α- or β-ICL at a single site and extracted RNA for transcriptome analysis. Results show that the stereochemical configuration of the α/β-ICL is responsible for distinct gene expression changes in MCF-7 and K562 cells. Our data also show that, in MCF-7 cells, α-ICL treatment triggers a strong increase in CDKN1A expression which is also observed at the protein level, contrary to what happens upon β-ICL treatment. In addition, β-ICL treatment led to a strong downregulation of a greater number of genes than the α-ICL in both cell lines, in particular in K562 cells, which harbor a TP53 mutation. This suggests that the β-ICL toxicity relies on a mechanism which leads to an overall downregulation of gene expression and may explain the greater toxicity of DMC toward TP53 mutant cells.

Unveiling FDA-approved Drugs and Formulations in the Management of Bladder Cancer: A Review

Urological cancers are one of the most prevalent malignancies around the globe. Specifically, bladder cancer severely threatens the health of humans because of its heterogeneous and aggressive nature. Extensive studies have been conducted for many years in order to address the limitations associated with the treatment of solid tumors with selective substances. This article aims to provide a summary of the therapeutic drugs that have received FDA approval or are presently in the testing phase for use in the prevention or treatment of bladder cancer. In this review, FDA-approved drugs for bladder cancer treatment have been listed along with their dose protocols, current status, pharmacokinetics, action mechanisms, and marketed products. The article also emphasizes the novel preparations of these drugs that are presently under clinical trials or are in the approval stage. Thus, this review will serve as a single point of reference for scientists involved in the formulation development of these drugs.

Mitomycin C and its analog trigger cytotoxicity in MCF-7 and K562 cancer cells through the regulation of RAS and MAPK/ERK pathways

Mitomycin C (MC) is an anti-cancer drug which functions by forming interstrand crosslinks (ICLs) between opposing DNA strands. MC analog, 10-decarbamoyl mitomycin C (DMC), unlike MC, has stronger cytotoxic effects on cancer cells with TP53 mutation. We previously demonstrated that MC/DMC could activate p21WAF1/CIP1 in MCF-7 (TP53-proficient) and K562 (TP53 deficient) cells in a TP53-independent mode. We also found that MC/DMC regulate AKT activation in a TP53-dependent manner and that AKT deactivation is not associated with the activation of p21WAF1/CIP1 in response to MC/DMC treatment. RAS proteins are known players in the upstream mediated signaling of p21WAF1/CIP1 activation that leads to control of cell proliferation and cell death. Thus, this prompted us to investigate the effect of both drugs on the expression of RAS proteins and regulation of the MAPK/ERK signaling pathways in MCF-7 and K562 cancer cells. To accomplish this goal, we performed comparative label free proteomics profiling coupled to bioinformatics/complementary phosphoprotein arrays and Western blot validations of key signaling molecules. The MAPK/ERK pathway exhibited an overall downregulation upon MC/DMC treatment in MCF-7 cells but only DMC exhibited a mild downregulation of that same pathway in TP53 mutant K562 cells. Furthermore, treatment of MCF-7 and K562 cell lines with oligonucleotides containing the interstrand crosslinks (ICLs) formed by MC or DMC shows that both ICLs had a stronger effect on the downregulation of RAS protein expression in mutant TP53 K562 cells. We discuss the implication of this regulation of the MAPK/ERK pathway in relation to cellular TP53 status.

A minimal Fanconi Anemia complex in early diverging fungi

Fanconi Anemia (FA) pathway resolves DNA interstrand cross links (ICL). The FA pathway was initially recognized in vertebrates, but was later confirmed in other animals and speculated in fungi. FA proteins FANCM, FANCL and FANCJ are present in Saccharomyces cerevisiae but, their mechanism of interaction to resolve ICL is still unclear. Unlike Dikarya, early diverging fungi (EDF) possess more traits shared with animals. We traced the evolutionary history of the FA pathway across Opisthokonta. We scanned complete proteomes for FA-related homologs to establish their taxonomic distribution and analyzed their phylogenetic trees. We checked transcription profiles of FA genes to test if they respond to environmental conditions and their genomic localizations for potential co-localization. We identified fungal homologs of the activation and ID complexes, 5 out of 8 core proteins, all of the endonucleases, and deubiquitination proteins. All fungi lack FANCC, FANCF and FANCG proteins responsible for post-replication repair and chromosome stability in animals. The observed taxonomic distribution can be attributed to a gradual degradation of the FA pathway from EDF to Dikarya. One of the key differences is that EDF have the ID complex recruiting endonucleases to the site of ICL. Moreover, 21 out of 32 identified FA genes are upregulated in response to different growth conditions. Several FA genes are co-localized in fungal genomes which also could facilitate co-expression. Our results indicate that a minimal FA pathway might still be functional in Mucoromycota with a gradual loss of components in Dikarya ancestors.

Construction of Diversified Penta-Spiro-Heterocyclic and Fused-Heterocyclic Frameworks with Potent Antitumor Activity

Multiple-spiro/fused-heterocyclic frameworks containing indazolone are structurally unique and represent a class of potentially dominant skeletons. In this work, we successfully fulfilled Rh(III)-catalyst mediated substrate- and pH- controlled strategies to construct four novel types of complicated penta-spiro/fused-heterocyclic frameworks via C-H activation/[4+1] and [4+2] annulation cascades. This method had mild reaction conditions, a broad scope of substrates, moderate to good yields, and valuable applications, which could realize for the first time the generation of the novel di-spiro-heterocyclic and multiple fused-heterocyclic products with unique structures. More importantly, novel spiro[cyclohexane-indazolo[1,2-a]indazole] scaffold constructed by this method exhibited potent antitumor activity against a variety of refractory solid tumors and hematological malignancies in vitro. Overall, our work provided new insights into the construction of complex and diverse multiple spiro/fused-heterocyclic systems and offered novel valuable lead compounds for the discovery of antitumor drugs.