Prenatal developmental sequences of the esophageal epithelium in the New Zealand white rabbits: Light and electron microscopic analysis

Several morphogenetic sequences occur during esophageal development and birth defects occur due to defects in foregut morphogenesis. This work aimed to record the cellular events in the morphogenesis of rabbits' esophageal epithelium. On the 16th day of gestation, the esophageal epithelium varied from stratified ciliated columnar to stratified squamous type. The surface epithelium presented mucous cells with mucigen granules of various sizes occupying their supranuclear cytoplasm. Cytoplasmic vacuolation was evident in all layers of the esophageal epithelium at this age. On the 18th gestational day, some light cells could be detected in the middle portion of the epithelium, while others occupied the whole epithelial length. On the 21st day, mucous cells are more frequently observed at the apical esophageal part as well as at the surface epithelium. Numerous elongated dark cells could be distinguished embedded between the basal cells. On the 24th gestational day the number of the mucous cells reached its peak. Reaching the 30th gestational day, several lamellar bodies, a keratinized layer and mitotic divisions could be demonstrated, and the number of both mucous and dark cells was greatly decreased. Collectively, detection of surface mucous and dark cells together with the non-cornified surface in some regions of the rabbit esophageal epithelium at the end of gestation ensure a postnatal development to reach the adult epithelium essential to sustain the passage of the harsh raw food. Future immunohistochemical studies are recommended to investigate the components of secretions in mucous cells and functional studies to highlight the dark cells significance. RESEARCH HIGHLIGHTS: Esophageal epithelium of fetal rabbit was analyzed by light and transmission microscopy. Surface epithelium presented mucous cells with mucigen granules of various sizes. They reached their maximum number on 24th day then decreased. On the 16th day, cytoplasmic vacuolation was evident in all epithelial layers. On the 21st day, numerous elongated dark cells could be distinguished embedded between the basal cells. Before birth, several lamellar bodies, a keratinized layer and mitotic divisions could be demonstrated, and the number of both mucous and dark cells was greatly decreased.

Rutin Linoleate Triggers Oxidative Stress-Mediated Cytoplasmic Vacuolation in Non-Small Cell Lung Cancer Cells

Lung cancer (LC) represents one of the most prevalent health issues globally and is a leading cause of tumor-related mortality. Despite being one the most attractive compounds of plant origin due to its numerous biological properties, the therapeutic applications of rutin (RUT) are limited by its disadvantageous pharmacokinetics. Thus, the present study aimed to evaluate in vitro the application of two RUT fatty acids bioconjugates, rutin oleate (RUT-O) and rutin linoleate (RUT-L), as potential improved RUT-based chemotherapeutics in non-small cell lung cancer (NSCLC) treatment. The results indicate that both compounds lacked cytotoxic potential in EpiAirway™ tissues at concentrations up to 125 µM. However, only RUT-L exerted anti-tumorigenic activity in NCI-H23 NSCLC cells after 24 h of treatment by reducing cell viability (up to 47%), proliferation, and neutral red uptake, causing cell membrane damage and lactate dehydrogenase (LDH) leakage, affecting cytoskeletal distribution, inducing cytoplasmic vacuolation, and increasing oxidative stress. The cytopathic effects triggered by RUT-L at 100 and 125 µM are indicators of a non-apoptotic cell death pathway that resembles the characteristics of paraptosis. The novel findings of this study stand as a basis for further investigations on the anti-cancer properties of RUT-L and their underlying mechanisms.

Antiparasitic effect of copper alloy mesh on tomont stage of Cryptocaryon irritans in aquaculture

Copper alloy sheets have been shown to prevent cryptocaryoniasis. Therefore, we studied the potential efficiency of copper alloy mesh (CAM) in aquaculture tanks to prevent cryptocaryoniasis outbreaks. The effectivenesses of CAM against the tomont stage of Cryptocaryon irritans and in protecting fish from cryptocaryoniasis were tested both in vitro and in vivo. The mortality rate of C. irritans tomonts increased as the contact time with CAM rose and peaked at 70 min (100% of mortality). Morphological changes were observed such as the shrinking of the protoplasm of the treated tomonts, resulting in a larger gap between the cytoplasm and the cyst wall. Mitochondrial dysfunction due to shrinkage in the inner portion, outer and inner mitochondrial membrane damage and cytoplasmic vacuolation was revealed by ultrastructural analysis. The use of CAM effectively preventing reinfection was also provided. In comparison with group B (infected fish without CAM), both groups A (uninfected fish as a control group) and C (infected fish treated with CAM) had a 100% survival rate until the end of the trial. CAM has the same anticryptocaryoniasis effect as copper alloy sheets but is more advantageous due to its lightweight, reduced labor cost and lower purchase cost. It is noticeable that CAM exposure also prevents the excessive accumulation of copper ions in aquaculture sea water.

Synergistic killing effect of paclitaxel and honokiol in non-small cell lung cancer cells through paraptosis induction

PURPOSE

Paclitaxel is an anticancer drug for the treatment of non-small cell lung cancer (NSCLC). However, drug-resistance remains a major problem. Honokiol is a natural component which has been found to exhibit anti-tumor activity. Paclitaxel and honokiol have been reported to be able to induce paraptosis. The aim of this study was to investigate whether honokiol can reverse paclitaxel resistance by inducing paraptosis in NSCLC cells.

METHODS

NSCLC cell lines H1650 (paclitaxel-sensitive), H1299 and H1650/PTX (intrinsic and acquired paclitaxel-resistant, respectively) were used to assess the cytotoxic effects of paclitaxel and honokiol. Light and transmission electron microscopy were performed to detect cytoplasmic vacuolation. In vitro cell viability and clonogenic survival assays, as well as in vivo xenograft assays were conducted to test synergistic killing effects of paclitaxel and honokiol on NSCLC cells. Western blotting, flow cytometry and immunofluorescence were performed to evaluate paraptosis-regulating mechanisms.

RESULTS

We found that combination treatment with paclitaxel and honokiol synergistically killed H1650, H1299 and H1650/PTX cells by inducing paraptosis, which is characterized by cytoplasmic vacuolation. Moreover, paclitaxel/honokiol treatment resulted in a significant growth delay in H1299 xenograft tumors that showed extensive cytoplasmic vacuolation. Mechanistically, proteasomal inhibition-mediated endoplasmic reticulum (ER) stress and unfolded protein responses leading to ER dilation, and the disruption of intracellular Ca2+ homeostasis and mitochondrial Ca2+ overload resulting in mitochondrial disfunction, were found to be involved in paclitaxel/honokiol-induced paraptosis. Cellular protein light chain 3 (LC3) may play an important role in paclitaxel/honokiol induced cytoplasmic vacuolation and NSCLC cell death.

CONCLUSIONS

Combination of honokiol and paclitaxel may represent a novel strategy for the treatment of paclitaxel-resistant NSCLC.

Proteasomal dysfunction and ER stress triggers 2'-hydroxy-retrochalcone-induced paraptosis in cancer cells

Chalcones are biologically active class of compounds, known for their anticancer activities. Here we show for the first time that out of the six synthetic derivatives of chalcone tested, 2'-hydroxy-retrochalcone (HRC) was the most effective in inducing extensive cytoplasmic vacuolation mediated death called paraptosis in malignant breast and cervical cancer cells. The cell death by HRC is found to be nonapoptotic in nature due to the absence of DNA fragmentation, PARP cleavage, and phosphatidylserine externalization. It was also found to be nonautophagic as there was an increase in the levels of autophagic markers LC3I, LC3II and p62. Immunofluorescence with the endoplasmic reticulum (ER) marker protein calreticulin showed that the cytoplasmic vacuoles formed were derived from the ER. This ER dilation was due to ER stress as evidenced from the increase in polyubiquitinated proteins, Bip and CHOP. Docking studies revealed that HRC could bind to the Thr1 residue on the active site of the chymotrypsin-like subunit of the proteasome. The inhibition of proteasomal activity was further confirmed by the fluorescence based assay of the chymotrypsin-like subunit of the 26S proteasome. The cell death by HRC was also triggered by the collapse of mitochondrial membrane potential and depletion of ATP. Pretreatment with thiol antioxidants and cycloheximide were able to inhibit this programmed cell death. Thus our data suggest that HRC can effectively kill cancer cells via paraptosis, an alternative death pathway and can be a potential lead molecule for anticancer therapy.

Cannabinoid Combination Induces Cytoplasmic Vacuolation in MCF-7 Breast Cancer Cells

This study evaluated the synergistic anti-cancer potential of cannabinoid combinations across the MDA-MB-231 and MCF-7 human breast cancer cell lines. Cannabinoids were combined and their synergistic interactions were evaluated using median effect analysis. The most promising cannabinoid combination (C6) consisted of tetrahydrocannabinol, cannabigerol (CBG), cannabinol (CBN), and cannabidiol (CBD), and displayed favorable dose reduction indices and limited cytotoxicity against the non-cancerous breast cell line, MCF-10A. C6 exerted its effects in the MCF-7 cell line by inducing cell cycle arrest in the G₂ phase, followed by the induction of apoptosis. Morphological observations indicated the induction of cytoplasmic vacuolation, with further investigation suggesting that the vacuole membrane was derived from the endoplasmic reticulum. In addition, lipid accumulation, increased lysosome size, and significant increases in the endoplasmic reticulum chaperone protein glucose-regulated protein 78 (GRP78) expression were also observed. The selectivity and ability of cannabinoids to halt cancer cell proliferation via pathways resembling apoptosis, autophagy, and paraptosis shows promise for cannabinoid use in standardized breast cancer treatment.

Hepatic histopathological and ultrastructural alterations induced by 10 nm silver nanoparticles

Silver nanoparticles (Ag NPs) are invested in various sectors and are becoming more persistent in our ambient environment with potential risk on our health and the ecosystems. The current study aims to investigate the histological, histochemical and ultrastructural hepatic changes that might be induced by 10 nm silver nanomaterials. Male mice (BALB/C) were exposed for 35 injections of daily dose of 10 nm Ag NPs (2 mg/kg). Liver tissues were subjected to examination by light and electron microscopy for histological, histochemical and ultrastructural alterations. Exposure to Ag NPs induced Kupffer cells hyperplasia, sinusoidal dilatation, apoptosis, ground glass hepatocytes appearance, nuclear changes, inflammatory cells infiltration, hepatocytes degeneration and necrosis. In addition, 10 nm Ag NPs induced histochemical alterations mainly glycogen depletion with no hemosiderin precipitation. Moreover, these nanomaterials exhibited ultrastructure alterations including mitochondrial swelling and cristolysis, cytoplasmic vacuolation, apoptosis, multilammellar myelin figures formation and endoplasmic destruction and reduction. The findings revealed that Ag NPs can induce alterations in the hepatic tissues, the chemical components of the hepatocytes and in the ultrastructure of the liver. One may also conclude that small size Ag NPs, which are increasingly used in human products could cause various toxigenic responses to all hepatic tissue components.

Xanthohumol induces paraptosis of leukemia cells through p38 mitogen activated protein kinase signaling pathway

Xanthohumol as a natural polyphenol demonstrates an anticancer activity, but its underlying mechanism remains unclear. In this study, we showed that xanthohumol (XN) induces paraptosis of leukemia cells. The paraptosis is one cell death which is characterized by dilation of the endoplasmic reticulum and/or mitochondria. The results demonstrated that XN treatment significantly inhibited cell proliferation and triggered extensive cytoplasmic vacuolation of HL-60 leukemia cells, but it did not cause the cleavage of caspase-3 protein or apoptosis. In contrast, XN treatment resulted in LC3-II accumulation through blocking of autophagosome maturation. Interestingly, the induction of cytoplasmic vacuolization by XN is not associated with autophagy modulated by XN, therefore, XN-induced cell death of HL-60 leukemia cells is not the classical apoptotic cell death. Intriguingly, XN treatment triggered the dilatation of endoplasma reticulum (ER) and induced ER stress by upregulating C/EBP homologous protein and unfolded protein response regulator Grp78/Bip. Furthermore, XN treatment triggered p38 mitogen activated protein kinase and its specific inhibitor inhibited the paraptosis of HL-60 leukemia cells by XN. In conclusion, we for the first time demonstrated that XN treatment can induce paraptosis of leukemia cells through activation of p38 MAPK signaling.

Wheat germ agglutinin-induced paraptosis-like cell death and protective autophagy is mediated by autophagy-linked FYVE inhibition

Wheat germ agglutinin (WGA) is a lectin that specifically binds cell surface glycoproteins and disrupts nuclear pore complex function through its interaction with POM121. Our data indicate WGA induces paraptosis-like cell death without caspase activation. We observed the main features of paraptosis, including cytoplasmic vacuolation, endoplasmic reticulum dilation and increased ER stress, and the unfolded protein response in WGA-treated cervical carcinoma cells. Conversion of microtubule-associated protein I light chain 3 (LC3-I) into LC3-II and punctuate formation suggestive of autophagy were observed in WGA-treated cells. WGA-induced autophagy antagonized paraptosis in HeLa and CaSKi cells, which expressed autophagy-linked FYVE (Alfy) protein, but not in SiHa cells that did not express Alfy. Alfy knockdown in HeLa cells induced paraptosis-like cell death. These data indicate that WGA-induced cell death occurs through paraptosis and that autophagy may exert a protective effect. WGA treatment and Alfy inhibition could be an effective therapeutic strategy for apoptosis-resistant cervical cancer cells.

Active vacuolar H+ ATPase and functional cycle of Rab5 are required for the vacuolation defect triggered by PtdIns(3,5)P2 loss under PIKfyve or Vps34 deficiency

The two evolutionarily conserved mammalian lipid kinases Vps34 and PIKfyve are involved in an important physiological relationship, whereby the former produces phosphatidylinositol (PtdIns) 3P that is used as a substrate for PtdIns(3,5)P2 synthesis by the latter. Reduced production of PtdIns(3,5)P2 in proliferating mammalian cells is phenotypically manifested by the formation of multiple translucent cytoplasmic vacuoles, readily rescued upon exogenous delivery of PtdIns(3,5)P2 or overproduction of PIKfyve. Although the aberrant vacuolation phenomenon has been frequently used as a sensitive functional measure of localized PtdIns(3,5)P2 reduction, cellular factors governing the appearance of cytoplasmic vacuoles under PtdIns3P-PtdIns(3,5)P2 loss remain elusive. To gain further mechanistic insight about the vacuolation process following PtdIns(3,5)P2 reduction, in this study we sought for cellular mechanisms required for manifestation of the aberrant endomembrane vacuoles triggered by PIKfyve or Vps34 dysfunction. The latter was achieved by various means such as pharmacological inhibition, gene disruption, or dominant-interference in several proliferating mammalian cell types. We report here that inhibition of V-ATPase with bafilomycin A1 as well as inactivation of the GTP-GDP cycle of Rab5a GTPase phenotypically rescued or completely precluded the cytoplasmic vacuolization despite the continued presence of inactivated PIKfyve or Vps34. Bafilomycin A1 also restored the aberrant EEA1-positive endosomes, enlarged upon short PIKfyve inhibition with YM201636. Together, our work identifies for the first time that factors such as active V-ATPase or functional Rab5a cycle are acting coincidentally with the PtdIns(3,5)P2 reduction in triggering formation of aberrant cytoplasmic vacuoles under PIKfyve or Vps34 dysfunction.