Drug-induced Morphological Changes Research Articles

Antitumor Potential of the Isoflavonoids (+)- and (-)-2,3,9-Trimethoxypterocarpan: Mechanism-of-Action Studies.

Synthetically derived samples of (+)-(6aS,11aS)-2,3,9-trimethoxypterocarpan [(+)-1] and its enantiomer [(-)-1], both of which are examples of naturally occurring isoflavonoids, were evaluated, together with the corresponding racemate, as cytotoxic agents against the HL-60, HCT-116, OVCAR-8, and SF-295 tumor cell lines. As a result it was established that compound (+)-1 was particularly active with OVCAR-8 cells being the most sensitive and responding in a dose-dependent manner. A study of cell viability and drug-induced morphological changes revealed the compound causes cell death through a mechanism characteristic of apoptosis. Finally, a computational study of the interactions of compound (+)-1 and (S)-monastrol, an established, synthetically derived, potent, and cell-permeant inhibitor of mitosis, with the kinesin-type protein Eg5 revealed that both bind to this receptor in a similar manner. Significantly, compound (+)-1 binds with greater affinity, an effect attributed to the presence of the associated methoxy groups.

134 - Structural Variations in Selenium Drugs Determine Selective Toxicity towards Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer affecting approximately 20% of women. TNBC cells lack three key receptors: progesterone, oestrogen and Her2, and as a result, TNBC cannot be treated using existing targeted therapies; therefore patients have an extremely poor prognosis. Recently selenium based drugs have been proposed as therapeutics to treat a range of disorders, and here we investigated the potential of these drugs to target TNBC. Representative selenium compounds diphenyl selenide (DPS) and diphenyl diselenide (DPDS) were characterised by their cytotoxicity against the TNBC cell lines: MDA-MB-231, MDA-MB-468 and HS-578T and, to probe selectivity, against the non-TNBC line SK-BR-3, which expresses Her2. DPS showed no anti-cancer action against any breast cancer cells, however, its structural analogue DPDS showed pronounced cytotoxicity in the range 5-20 μM against all TNBC cell lines studied. Interestingly neither drug displayed cytotoxicity towards a non-TNBC cell line, indicating that DPDS may be capable of selectively destroying TNBC cells without damaging the surrounding healthy cells in the cancerous tissue. Mechanistic analysis indicated that DPDS induced apoptosis in TNBC via a caspase-3 dependent mechanism which correlated with p53 upregulation and membrane changes characteristic of apoptosis. In addition, drug-induced morphological changes characteristic of apoptosis, including membrane disruption and cell shrinkage, were observed in all TNBC cell lines using phase contrast microscopy. These findings provide the first evidence that DPDS may be a selective anti-cancer drug towards TNBC, and identify crucial structural features for TNBC activity, paving the way towards a next generation treatment for a cancer with a notoriously low survival rate.

Profiling of the effects of antifungal agents on yeast cells based on morphometric analysis.

The incidence of fungal infection and evolution of multidrug resistance have increased the need for new antifungal agents. To gain further insight into the development of antifungal drugs, the phenotypic profiles of currently available antifungal agents of three classes-ergosterol, cell wall and nucleic acid biosynthesis inhibitors-were investigated using yeast morphology as a chemogenomic signature. The comparison of drug-induced morphological changes with the deletion of 4718 non-essential genes not only confirmed the mode of action of the drugs but also revealed an unexpected connection among ergosterol, vacuolar proton-transporting V-type ATPase and cell-wall-targeting drugs. To improve, simplify and accelerate drug development, we developed a systematic classifier that sorts a newly discovered compound into a class with a similar mode of action without any mutant information. Using well-characterized agents as target unknown compounds, this method successfully categorized these compounds into their respective classes. Based on our data, we suggest that morphological profiling can be used to develop novel antifungal drugs.

RXRα-regulated liver SAMe and GSH levels influence susceptibility to alcohol-induced hepatotoxicity

Retinoids influence the pathogenesis of alcohol liver disease (ALD). To analyze the impact of retinoid X receptor alpha (RXRα) on ALD, alcohol-induced hepatotoxicity was studied using mice fed ethanol intragastrically for 25 days. Alcohol-induced microvesicular fat around the central vein and drug-induced morphological changes (loss of rough endoplasmic reticulum, pinkish cytoplasm, and enlarged hepatocyte) in the pericentral area were observed in the liver of wild-type mice. In the hepatocyte RXRα-deficient mouse liver, alcohol induced fat accumulation, mitosis, acute inflammation, and necrosis. The histology score after alcohol treatment was significantly higher in mutant mice than in wild-type mice. However, drug-induced morphological changes were not apparent in alcohol-treated hepatocyte RXRα-deficient mice. Northern analysis showed that the basal and alcohol-induced CYP2B, CYP2A, and CYP3A mRNA levels were lower in hepatocyte RXRα-deficient mice than in wild-type mice, which in turn may protect mutant mice from morphological changes. Compared with wild-type mice, hepatocyte RXRα-deficient mice have significant lower levels of S-adenosylmethionine and glutathione, which is further reduced after alcohol treatment, and that may account for severe liver injury induced by alcohol. The overall result suggests an important role of RXRα in preventing alcohol-induced liver injury.

Paclitaxel-induced apoptotic changes followed by time-lapse video microscopy in cell lines established from head and neck cancer.

Paclitaxel (Taxol) is a potent chemotherapeutic drug for squamous-cell carcinoma (SCC) of the head and neck in vitro with microtubule-stabilizing activity that arrests cells in G2-M. To study the mechanism of its cytotoxic effect on SCC in vitro, we exposed five laryngeal SCC cell lines to 10 nM paclitaxel. The cell lines were studies by time-lapse video microscopy for 96 h, and by agarose gel electrophoresis. Paclitaxel blocked the cells in the premitotic phase for 6-24 h, after which the cells died morphologically by apoptosis. Mitotically arrested cells were seen within a few minutes after exposure to paclitaxel. No mitoses were seen in the paclitaxel-treated cells. A few apoptoses were also seen in the control cultures grown without paclitaxel, but they represented only 6%-20% of the frequency of apoptoses seen in the paclitaxel-treated group. In some paclitaxel-treated cultures the cells escaped the mitotic arrest without cytokinesis and formed multinucleated cells that eventually died. Agarose gel electrophoresis showed oligonucleosomal DNA fragmentation characteristic of apoptosis. We conclude that time-lapse video microscopy is an efficient method of observing drug-induced morphological changes in cell culture. Paclitaxel at a 10 nM concentration rapidly induces a premitotic block, which usually leads to apoptotic cell death. In some cases multinucleated cells are formed that morphologically also eventually die by apoptosis.

Bupivacaine: Morphological effects on spinal cords of cats and durations of spinal anesthesia in sheep

Summary Bupivacaine HCl, 0.25, 0.5 and 1.0%, was administered epidurally to cats and the duration of block recorded. Subsequent gross and microscopic examination of the spinal cords revealed morphological changes due to the presence of the polyethylene catheter in the epidural space. There was no evidence of drug-induced morphological changes. Spinal anesthesia with 0.25, 0.5 and 1.0% bupivacaine HCl was performed in sheep, and durations of sensory analgesia and motor block were recorded. Despite certain limitations, inherent in all animal models, the sheep is an excellent model for the study of spinal anesthetic agents.