Knowledge and attitude toward theranostics among Nuclear Medicine Technologists

This study was conducted to determine the knowledge and attitude of nuclear medicine technologists toward theranostics. This research utilized a quantitative correlational research design. Data were gathered from 69 practicing nuclear medicine technologists, specifically those that do not perform or have theranostics procedures. The data were gathered using a self-made questionnaire and statistically treated using frequency, percentage, range, mean, standard deviation, t-test, ANOVA, Kruskal-Wallis H test, Mann-Whitney U test, and Spearman Rank Order Correlation. Findings show that the majority of the respondents are male, and most are 20-30 years old. Most of the respondents have good knowledge and show a “positive attitude” toward theranostics. In general, there are no significant differences in the knowledge of the respondents about theranostics when they are grouped according to sex, years of experience and type of hospital they are currently employed in. However, there is a significant difference when grouped according to age, where the 31–40-year-old group showed a higher level of knowledge than the 20-30-year-old group possibly due to learning more about practices with theranostics. With the respondents’ attitude toward theranostics, there are no significant differences when they are grouped according to age, sex, years of experience, and type of hospital they are currently employed in. The findings also show that there is a weak positive relationship between the knowledge and attitude of the respondents toward theranostics. Generally, the results show that nuclear medicine technologists have very good attitude toward and good knowledge of theranostics

C6-ceramide synergistically potentiates the anti-tumor effects of histone deacetylase inhibitors via AKT dephosphorylation and α-tubulin hyperacetylation both in vitro and in vivo

Histone deacetylase inhibitors (HDACIs) have shown promising anti-tumor effects for a variety of malignancies, however, many tumors are reportedly resistant to them. In this study, we made a novel discovery that co-administration of HDACIs (Trichostatin A (TSA) and others) and exogenous cell-permeable short-chain ceramide (C6) results in striking increase in cancer cell death and apoptosis in multiple cancer cells. These events are associated with perturbations in diverse cell signaling pathways, including inactivation of Akt/mTOR and increase in α-tubulin acetylation (both in vivo and in vitro). TSA interacts in a highly synergistic manner with C6-ceramide to disrupt HDAC6/protein phosphatase 1 (PP1)/tubulin complex, to induce α-tubulin hyperacetylation, and to release and activate PP1, which then leads to AKT dephosphorylation and eventually causes cancer cell death. Interestingly, TSA itself results in short-term ceramide accumulation, which as a result of metabolic (glycosylation) removal, does not result in evident increase of cancer cell death. However, adding C6-ceramide led to a very pronounced increase in ceramide level and marked increase in cell death. Importantly, the effective synergistic anti-tumor activity of TSA plus C6-ceramide is also seen in in vivo mice xenograft pancreatic and ovarian cancer models, indicating that this regimen (HDACI plus C6-ceramide) may represent a more effective form of therapy against pancreatic and ovarian carcinoma

Altered sphingolipid metabolism in multidrug-resistant ovarian cancer cells is due to uncoupling of glycolipid biosynthesis in the Golgi apparatus

Multidrug-resistant tumor cells display enhanced levels of glucosylceramide. In this study, we investigated how this relates to the overall sphingolipid composition of multidrug-resistant ovarian carcinoma cells and which mechanisms are responsible for adapted sphingolipid metabolism. We found in multidrug-resistant cells substantially lower levels of lactosylceramide and gangliosides in sharp contrast to glucosylceramide, galactosylceramide, and sphingomyelin levels. This indicates a block in the glycolipid biosynthetic pathway at the level of lactosylceramide formation, with concomitant accumulation of glucosylceramide. A series of observations exclude regulation at the enzyme level as the underlying mechanism. First, reduced lactosylceramide formation occurred only in intact resistant cells whereas cell-free activity of lactosylceramide synthase was higher compared with the parental cells. Second, the level of lactosylceramide synthase gene expression was equal in both phenotypes. Third, glucosylceramide synthase (mRNA and protein) expression and activity were equal or lower in resistant cells. Based on the kinetics of sphingolipid metabolism, the observation that brefeldin A does not restore lactosylceramide synthesis, and altered localization of lactosylceramide synthase fused to green fluorescent protein, we conclude that lactosylceramide biosynthesis is highly uncoupled from glucosylceramide biosynthesis in the Golgi apparatus of resistant cells

The golgi-associated COPI-coated buds and vesicles contain beta/gamma -actin

It has been shown previously that the morphology and subcellular positioning of the Golgi complex is controlled by actin microfilaments. To further characterize the association between actin microfilaments and the Golgi complex, we have used the Clostridium botulinum toxins C2 and C3, which specifically inhibit actin polymerization and cause depolymerization of F-actin in intact cells by the ADP ribosylation of G-actin monomers and the Rho small GTP-binding protein, respectively. Normal rat kidney cells treated with C2 showed that disruption of the actin and the collapse of the Golgi complex occurred concomitantly. However, when cells were treated with C3, the actin disassembly was observed without any change in the organization of the Golgi complex. The absence of the involvement of Rho was further confirmed by the treatment with lysophosphatidic acid or microinjection with the constitutively activated form of RhoA, both of which induced the stress fiber formation without affecting the Golgi complex. Immunogold electron microscopy in normal rat kidney cells revealed that beta- and gamma-actin isoforms were found in Golgi-associated COPI-coated buds and vesicles. Taken together, the results suggest that the Rho signaling pathway does not directly regulate Golgi-associated actin microfilaments, and that beta- and gamma-actins might be involved in the formation and/or transport of Golgi-derived vesicular or tubular intermediates

Actin and microtubule regulation of Trans-Golgi network architecture, and copper-dependent protein transport to the cell surface

The Menkes disease ATPase (MNK) is a copper transporter that localizes to the mammalian trans-Golgi network (TGN) and shows substantial co-localization with a ubiquitous TGN resident protein and marker, TGN46. We tested our hypothesis that these two TGN residents and integral membrane proteins are localized to biochemically distinct TGN sub-compartments using constitutively active mutant proteins and drugs that disrupt membrane traffic, lumenal pH and the cellular cytoskeleton. The pH-disrupting agent, monensin, causes MNK to be more diffusely distributed with partial separation of staining patterns for these two TGN residents. Expression of a constitutively active Rho-kinase (ROCK-KIN), which causes formation of juxta-nuclear astral actin arrays, also effects separation of MNK and TGN46 staining patterns. Treatment of ROCK-KIN expressing cells with latrunculin B, an actin-depolymerizing agent, causes complete overlap of MNK and TGN46 staining patterns with concomitant disappearance of polymerized actin. When microtubules are depolymerized in ROCK-KIN expressing cells by nocodazole, both MNK and TGN46 are found in puncate structures throughout the cell. However, a substantial proportion of MNK is still found in a juxta-nuclear location in contrast to TGN46. Actin distribution in these cells reveals that juxta-nuclear MNK is distinct to the astral actin clusters in ROCK-KIN expressing cells where the microtubules were depolymerized. The TGN to cell-surface transport of MNK requires both actin and microtubule networks, whilst the constitutive trafficking of proteins is independent of actin. Taken together, our findings indicate that at least two TGN sub-domains are regulated by separate cytoskeletal dynamics involving actin and tubulin

The Na+/H+ Exchanger NHE6 in the Endosomal Recycling System Is Involved in the Development of Apical Bile Canalicular Surface Domains in HepG2 Cells

This study underscores the emerging role of NHE6 as a novel regulatory protein in the apical surface development of human hepatoma HepG2 cells. A limited range of endosomal pH facilitated by NHE6.1 is suggested to be important for securing the polarized distribution of membrane lipids and proteins and maintenance of apical bile canaliculi