Tributyltin induces G2/M cell cycle arrest via NAD(+)-dependent isocitrate dehydrogenase in human embryonic carcinoma cells

Evaluation of Anticancer Activity of Novel and Tumor-Targeted Glutamine-Conjugated Organotin(IV) Compounds in Colorectal Cancer─An In Vitro and In Vivo Study

Over the years, numerous ligand-based organotin(IV) Schiff base compounds have shown remarkable cytotoxicity and anticancer activities, but their clinical use is restricted by systemic toxicity, prompting the search for targeted therapies. Targeted delivery can be enhanced by exploiting the inherent characteristics of cancer cells such as glutamine addiction, which is essential to support cellular biosynthesis and cell growth to sustain aberrant proliferation. Our previous study revealed glutamine-conjugated organotin(IV) compounds have strong DNA/protein affinities, favorable in silico ADME profiles, and significant antiproliferative activity. In this study, these compounds demonstrated significant cytotoxicity against human colon carcinoma and adenocarcinoma cell lines via the induction of cell cycle arrest and apoptosis. In DMH/DSS-induced experimental colon carcinogenesis, these compounds reduced tumor burden and volume and inhibited cell proliferation and induced apoptosis, with minimal toxicity. Tissue distribution studies revealed selective accumulation in the colon. These findings support their potential as chemotherapeutic candidates for colon cancer.

Biochemical mechanisms of tributyltin chloride-induced cell toxicity in Sertoli cells

Tributyltin chloride (TBTCL) is a widely used fungicide and heat stabilizer in compositions of PVC. TBTCL has been detected in human bodies and potentially causes harmful effects on humans' thyroid, cardiovascular and other organs. As one of the first examples of endocrine disruptors, the toxicity effects of TBTCL on the male reproduction system have aroused concerns. However, the potential cellular mechanisms are not fully explored. In the current study, by using Sertoli cells, a critical regulator of spermatogenesis as a cell model, we showed that with 200 nM exposure for 24 h, TBTCL causes apoptosis and cell cycle arrest. RNA sequencing analyses suggested that TBTCL probably activates endoplasmic reticulum (ER) stress, and disrupts autophagy. Biochemical analysis showed that TBTCL indeed induces ER stress and the dysregulation of autophagy. Interestingly, activation of ER stress and inhibition of autophagy is responsible for TBTCL-induced apoptosis and cell cycle arrest. Our results thus uncovered a novel insight into the cellular mechanisms for TBTCL-induced toxicology in Sertoli cells.

Triphenyltin(IV) dithiocarbamate compound induces genotoxicity and cytotoxicity in K562 human erythroleukemia cells primarily via mitochondria-mediated apoptosis

The novel di-and triphenyltin(IV) dithiocarbamate compounds represented as R_nSnL₂ (where R = C₄H₉, C₆H₅; n = 2,3; L = N,N-dithiocarbamate), Ph₂Sn(N,N-diisopropyldithiocarbamate) (OC1), Ph₃Sn(N,N-diisopropyldithiocarbamate) (OC2), Ph₂Sn(N,N-diallyldithiocarbamate) (OC3), Ph₃Sn(N,N-diallyldithiocarbamate) (OC4), and Ph₂Sn(N,N-diethyldithiocarbamate) (OC5) were assessed for their cytotoxicity in K562 human erythroleukemia cells. All compounds inhibited the growth of cells at low micromolar concentrations (<10 μM), and the mechanism underlying their antiproliferative effects on K562 cells was apoptosis, as corroborated by the exposure of plasma membrane phosphatidylserine. OC2, which showed the most promising antiproliferative activity, was selected for further analyses. The results demonstrated that OC2 induced apoptosis in K562 cells via an intrinsic mitochondrial pathway triggered upon DNA damage, an early apoptotic signal. Subsequently, OC2 produced excessive intracellular reactive oxygen species. The role of oxidative stress was corroborated by the significant reduction in GSH levels and percentage of apoptosis in NAC-pretreated cells. OC2 could arrest the cell cycle progression in the S phase. These new findings elucidate the antiproliferative potential of OC2 in the K562 human erythroleukemia cells and warrant further investigation, specifically to determine the exact signaling pathway underlying its antileukemic efficacy.

Environmental Impacts on Male Reproductive Development: Lessons from Experimental Models

BACKGROUND

Male reproductive development in mammals can be divided into a gonadal formation phase followed by a hormone-driven differentiation phase. Failure of these processes may result in Differences in Sex Development (DSD), which may include abnormalities of the male reproductive tract, including cryptorchidism, hypospadias, infertility, and testicular germ cell cancer (TGCC). These disorders are also considered to be part of a testicular dysgenesis syndrome (TDS) in males. Whilst DSDs are considered to result primarily from genetic abnormalities, the development of TDS disorders is frequently associated with environmental factors.

SUMMARY

In this review, we will discuss the development of the male reproductive system in relation to DSD and TDS. We will also describe the experimental systems, including studies involving animals and human tissues or cells that can be used to investigate the role of environmental factors in inducing male reproductive disorders. We will discuss recent studies investigating the impact of environmental chemicals (e.g., phthalates and bisphenols), lifestyle factors (e.g., smoking) and pharmaceuticals (e.g., analgesics) on foetal testis development. Finally, we will describe the evidence, involving experimental and epidemiologic approaches, for a role of environmental factors in the development of specific male reproductive disorders, including cryptorchidism, hypospadias, and TGCC.

KEY MESSAGES

Environmental exposures can impact the development and function of the male reproductive system in humans. Epidemiology studies and experimental approaches using human tissues are important to translate findings from animal studies and account for species differences in response to environmental exposures.

Cellular Basis of Organotin(IV) Derivatives as Anticancer Metallodrugs: A Review

Organotin(IV) compounds have wide applications in industrial and agricultural fields owing to their ability to act as poly(vinyl chloride) stabilizers and catalytic agents as well as their medicinal properties. Moreover, organotin(IV) compounds may have applications as antitumor, anti-inflammatory, antifungal, or antimicrobial agents based on the observation of synergistic effects following the binding of their respective ligands, resulting in the enhancement of their biological activities. In this review, we describe the antiproliferative activities of organotin(IV) compounds in various human cancer cell lines based on different types of ligands. We also discuss the molecular mechanisms through which organotin(IV) compounds induce cell death via apoptosis through the mitochondrial intrinsic pathway. Finally, we present the mechanisms of cell cycle arrest induced by organotin(IV) compounds. Our report provides a basis for studies of the antitumor activities of organotin(IV) compounds and highlights the potential applications of these compounds as anticancer metallodrugs with low toxicity and few side effects.

New triorganotin(iv) compounds with aromatic carboxylate ligands: synthesis and evaluation of the pro-apoptotic mechanism

Three new organotin(iv) carboxylate compounds were synthesized and structurally characterized by elemental analysis and FT-IR and multinuclear NMR (1H, 13C, 119Sn) spectroscopy. Single X-ray crystallography reveals that compound C2 has a monoclinic crystal system with space group P21/c having distorted bipyramidal geometry defined by C3SnO2. The synthesized compounds were screened for drug-DNA interactions via UV-Vis spectroscopy and cyclic voltammetry showing good activity with high binding constants. Theoretical investigations also support the reactivity of the compounds as depicted from natural bond orbital (NBO) analysis using Gaussian 09. Synthesized compounds were initially evaluated on two cancer (HeLa and MCF-7) cell lines and cytotoxicity to normal cells was evaluated using a non-cancerous (BHK-21) cell line. All the compounds were found to be active, with IC50 values less than that of the standard drug i.e. cisplatin. The cytotoxic effect of the most potent compound C2 was confirmed by LDH cytotoxicity assay and fluorescence imaging after PI staining. Apoptotic features in compound C2 treated cancer cells were visualized after DAPI staining while regulation of apoptosis was observed by reactive oxygen species generation, binding of C2 with DNA, a change in mitochondrial membrane potential and expression of activated caspase-9 and caspase-3 in cancer cells. Results are indicative of activation of the intrinsic pathway of apoptosis in C2 treated cancer cells.

5-Fluorouracil inhibits neural differentiation via Mfn1/2 reduction in human induced pluripotent stem cells

5-fluorouracil (5-FU) has been widely used for the treatment of tumors. Regardless of its widespread use as an anti-cancer drug, 5-FU therapy can cause several side effects, including developmental toxicity and neurotoxicity. However, the potential action of 5-FU at the early fetal stage has not yet been completely elucidated. In the present study, we investigated the effect of 5-FU exposure on neural induction, using human induced pluripotent stem cells (iPSCs) as a model of human fetal stage. 5-FU exposure reduced the expression of several neural differentiation marker genes, such as OTX2, in iPSCs. Since the neural differentiation process requires ATP as a source of energy, we next examined intracellular ATP content using iPSCs. We found that 5-FU decreased intracellular ATP levels in iPSCs. We further focused on the effects of 5-FU on mitochondrial dynamics, which plays a role of ATP production. We found that 5-FU induced mitochondrial fragmentation and reduced the level of mitochondrial fusion proteins, mitofusin 1 and 2 (Mfn1/2). Double knockdown of Mfn1/2 genes in iPSCs downregulated the gene expression of OTX2, suggesting that Mfn mediates neural differentiation in iPSCs. Taken together, these results indicate that 5-FU has a neurotoxicity via Mfn-mediated mitochondria dynamics in iPSCs. Thus, mitochondrial dysfunction in iPSCs could be used as a possible marker for cytotoxic effects of drugs.

Tributyltin Inhibits Neural Induction of Human Induced Pluripotent Stem Cells

Tributyltin (TBT), one of the organotin compounds, is a well-known environmental pollutant. In our recent study, we reported that TBT induces mitochondrial dysfunction, in human-induced pluripotent stem cells (iPSCs) through the degradation of mitofusin1 (Mfn1), which is a mitochondrial fusion factor. However, the effect of TBT toxicity on the developmental process of iPSCs was not clear. The present study examined the effect of TBT on the differentiation of iPSCs into the ectodermal, mesodermal, and endodermal germ layers. We found that exposure to nanomolar concentration of TBT (50 nM) selectively inhibited the induction of iPSCs into the ectoderm, which is the first step in neurogenesis. We further assessed the effect of TBT on neural differentiation and found that it reduced the expression of several neural differentiation marker genes, which were also downregulated by Mfn1 knockdown in iPSCs. Taken together, these results indicate that TBT induces developmental neurotoxicity via Mfn1-mediated mitochondrial dysfunction in iPSCs.

Angelicin inhibits human lung carcinoma A549 cell growth and migration through regulating JNK and ERK pathways

Angelicin is a member of a well-known class of chemical photosensitizes that have anticancer proper-ties in several cancer cell lines. However, the effects and the potential underlying mechanisms of angelicin action on human lung cancer cells remain unclear. Here, we report that angelicin has an essential role in inhibiting human lung carcinoma growth and metastasis. We found that angelicin markedly induced cell apoptosis and arrested the cell cycle in vitro. Angelicin also inhibited the migration of non-small cell lung cancer (NSCLC) A549 cells in a Transwell assay in a dose-dependent manner. In addition, after angelicin treatment, the expression levels of Bax, cleaved caspase-3 and cleaved caspase-9 were increased, and Bcl-2 expression was decreased. Moreover, our results indicate that angelicin inhibits NSCLC growth not only by downregulating cyclin B1, cyclin E1 and Cdc2, which are related to the cell cycle, but also by reducing MMP2 and MMP9 and increasing E-cadherin expression levels. Furthermore, extracellular signal-regulated kinase (ERK)1/2 and c-Jun NH2-terminal protein kinase (JNK)1/2 phosphorylation increased in parallel with the angelicin treatments. The inhibition of ERK1/2 and JNK1/2 by specific inhibitors significantly abrogated angelicin-induced cell apoptosis, cell cycle arrest and migration inhibition. We established in vivo A549 cell transplant and metastasis models and found that angelicin exerted a significant inhibitory effect on A549 cell growth and lung metastasis. Overall, our results suggested that angelicin is able to inhibit NSCLC A549 cell growth and metastasis by targeting ERK and JNK signaling, which demonstrates potential for NSCLC therapy.

Nicotine induces mitochondrial fission through mitofusin degradation in human multipotent embryonic carcinoma cells

Nicotine is considered to contribute to the health risks associated with cigarette smoking. Nicotine exerts its cellular functions by acting on nicotinic acetylcholine receptors (nAChRs), and adversely affects normal embryonic development. However, nicotine toxicity has not been elucidated in human embryonic stage. In the present study, we examined the cytotoxic effects of nicotine in human multipotent embryonal carcinoma cell line NT2/D1. We found that exposure to 10 μM nicotine decreased intracellular ATP levels and inhibited proliferation of NT2/D1 cells. Because nicotine suppressed energy production, which is a critical mitochondrial function, we further assessed the effects of nicotine on mitochondrial dynamics. Staining with MitoTracker revealed that 10 μM nicotine induced mitochondrial fragmentation. The levels of the mitochondrial fusion proteins, mitofusins 1 and 2, were also reduced in cells exposed to nicotine. These nicotine effects were blocked by treatment with mecamylamine, a nonselective nAChR antagonist. These data suggest that nicotine degrades mitofusin in NT2/D1 cells and thus induces mitochondrial dysfunction and cell growth inhibition in a nAChR-dependent manner. Thus, mitochondrial function in embryonic cells could be used to assess the developmental toxicity of chemicals.