The Golgi apparatus-complex is a highly dynamic organelle which is considered the “heart” of intracellular transportation. Since its discovery by Camillo Golgi in 1873, who described it as the ‘‘black reaction,’’ and despite the enormous volume of publications about Golgi, this apparatus remains one of the most enigmatic of the cytoplasmic organelles. A typical mammalian Golgi consists of a parallel series of flattened, disk-shaped cisternae which align into stacks. The tremendous volume of Golgi-related incoming and outgoing traffic is mediated by different motor proteins, including members of the dynein, kinesin, and myosin families. Yet in spite of the strenuous work it performs, Golgi contrives to maintain its monolithic morphology and orchestration of matrix and residential proteins. However, in response to stress, alcohol, and treatment with many pharmacological drugs over time, Golgi undergoes a kind of disorganization which ranges from mild enlargement to critical scattering. While fragmentation of the Golgi was confirmed in cancer by electron microscopy almost fifty years ago, it is only in recent years that we have begun to understand the significance of Golgi fragmentation in the biology of tumors. Below author would like to focus on how Golgi fragmentation opens the doors for cascades of fatal pathways which may facilitate cancer progression and metastasis. Among the issues addressed will be the most important cancer-specific hallmarks of Golgi fragmentation, including aberrant glycosylation, abnormal expression of the Ras GTPases, dysregulation of kinases, and hyperactivity of myosin motor proteins.

Core 2 N-acetylglucosaminyltransferase 1 (C2GnT1) is a key enzyme participating in the synthesis of core 2-associated sialyl Lewis x (C2-O-sLe^x), a ligand involved in selectin-mediated leukocyte trafficking and cancer metastasis. To accomplish that, C2GnT1 needs to be localized to the Golgi and this step requires interaction of its cytoplasmic tail (CT) with a protein that has not been identified. Employing C2GnT1 CT as the bait to perform a yeast two-hybrid screen, we have identified Golgi phosphoprotein 3 (GOLPH3) as a principal candidate protein that interacts with C2GnT1 and demonstrated that C2GnT1 binds to GOLPH3 via the LLRRR⁹ sequence in the CT. Confocal fluorescence microscopic analysis shows substantial Golgi co-localization of C2GnT1 and GOLPH3. Upon GOLPH3 knockdown, C2GnT1 is found mainly in the endoplasmic reticulum and decorated with complex-type N-glycans, indicating that the enzyme has been transported to the Golgi but is not retained. Also, we have found that a recombinant protein consisting of C2GnT1 CT^1–16-Leu^17–32-Gly^33–42-GFP is localized to the Golgi although the same construct with mutated CT (AAAAA⁹) is not. The data demonstrate that the C2GnT1 CT is necessary and sufficient for Golgi localization of C2GnT1. Furthermore, GOLPH3 knockdown results in reduced synthesis of C2-O-sLe^x associated with P-selectin glycoprotein ligand-1, reduced cell tethering to and rolling on immobilized P- or E-selectin, and compromised E-selectin-induced activation of spleen tyrosine kinase and cell adhesion to intercellular adhesion molecule-1 under dynamic flow. Our results reveal that GOLPH3 can regulate cell-cell interaction by controlling Golgi retention of C2GnT1.

Prostate cancer progression is associated with upregulation of sialyl-T antigen produced by β-galactoside α-2,3-sialyltransferase-1 (ST3Gal1) but not with core 2-associated polylactosamine despite expression of core 2 N-acetylglucosaminyltransferase-L (C2GnT-L/GCNT1). This property allows androgen-refractory prostate cancer cells to evade galectin-1 (LGALS1)–induced apoptosis, but the mechanism is not known. We have recently reported that Golgi targeting of glycosyltransferases is mediated by golgins: giantin (GOLGB1) for C2GnT-M (GCNT3) and GM130 (GOLGA2)-GRASP65 (GORASP1) or GM130-giantin for core 1 synthase. Here, we show that for Golgi targeting, C2GnT-L also uses giantin exclusively whereas ST3Gal1 uses either giantin or GM130-GRASP65. In addition, the compact Golgi morphology is detected in both androgen-sensitive prostate cancer and normal prostate cells, but fragmented Golgi and mislocalization of C2GnT-L are found in androgen-refractory cells as well as primary prostate tumors (Gleason grade 2–4). Furthermore, failure of giantin monomers to be phosphorylated and dimerized prevents Golgi from forming compact morphology and C2GnT-L from targeting the Golgi. On the other hand, ST3Gal1 reaches the Golgi by an alternate site, GM130-GRASP65. Interestingly, inhibition or knockdown of non-muscle myosin IIA (MYH9) motor protein frees up Rab6a GTPase to promote phosphorylation of giantin by polo-like kinase 3 (PLK3), which is followed by dimerization of giantin assisted by protein disulfide isomerase A3 (PDIA3), and restoration of compact Golgi morphology and targeting of C2GnT-L. Finally, the Golgi relocation of C2GnT-L in androgen-refractory cells results in their increased susceptibility to galectin-1–induced apoptosis by replacing sialyl-T antigen with polylactosamine. Implications: This study demonstrates the importance of Golgi morphology and regulation of glycosylation and provides insight into how the Golgi influences cancer progression and metastasis. Mol Cancer Res; 12(12); 1704–16. ©2014 AACR.

It has been a long-standing debate in the research and medical societies whether alcohol consumption is linked to the risk of prostate cancer (PCa). Many comprehensive studies from different geographical areas and nationalities have shown that moderate and heavy drinking is positively correlated with the development of PCa. Nevertheless, some observations could not confirm that such a correlation exists; some even suggest that wine consumption could prevent or slow prostate tumor growth. Here, we have rigorously analyzed the evidence both for and against the role of alcohol in PCa development. We found that many of the epidemiological studies did not consider other, potentially critical, factors, including diet (especially, low intake of fish, vegetables and linoleic acid, and excessive use of red meat), smoking, family history of PCa, low physical activity, history of high sexual activities especially with early age of first intercourse, and sexually transmitted infections. In addition, discrepancies between observations come from selectivity criteria for control groups, questionnaires about the type and dosage of alcohol, and misreported alcohol consumption. The lifetime history of alcohol consumption is critical given that a prostate tumor is typically slow-growing; however, many epidemiological observations that show no association monitored only current or relatively recent drinking status. Nevertheless, the overall conclusion is that high alcohol intake, especially binge drinking, is associated with increased risk for PCa, and this effect is not limited to any type of beverage. Alcohol consumption is also directly linked to PCa lethality as it may accelerate the growth of prostate tumors and significantly shorten the time for the progression to metastatic PCa. Thus, we recommend immediately quitting alcohol for patients diagnosed with PCa. We discuss the features of alcohol metabolism in the prostate tissue and the damaging effect of ethanol metabolites on intracellular organization and trafficking. In addition, we review the impact of alcohol consumption on prostate-specific antigen level and the risk for benign prostatic hyperplasia. Lastly, we highlight the known mechanisms of alcohol interference in prostate carcinogenesis and the possible side effects of alcohol during androgen deprivation therapy.

Glycosylation of secreted and membrane-bound mucins is carried out by glycosyltransferases localized to specific Golgi compartments according to the step in which each enzyme participates. However, the Golgi-targeting mechanisms of these enzymes are not clear. Herein, we investigate the Golgi-targeting mechanisms of core 1 β3 galactosyltransferase (C1GalT1) and core 2 β1,6-N-acetylglucosaminyltransferase-2 or mucus type (C2GnT-M), which participate in the early O-glycosylation steps. siRNAs, co-immunoprecipitation, and confocal fluorescence microscopy were employed to identify the golgins involved in the Golgi docking of vesicular complexes (VCs) that carry these two enzymes. We have found that these VCs use different golgins for docking: C2GnT-M-carrying VC (C2GnT-M-VC) utilizes Giantin, whereas C1GalT1-VC employs GM130-GRASP65 complex. However, in the absence of GRASP65, C1GalT1-VC utilizes GM130-Giantin complex. Also, we have found that these VCs are 1.1–1.2 μm in diameter, specific for each enzyme, and independent of coat protein complex II and I (COPII and COPI). These two fluorescently tagged enzymes exhibit different fluorescence recovery times in the Golgi after photobleaching. Thus, novel enzyme-specific Golgi-targeting mechanisms are employed by glycosyltransferases, and multiple Golgi docking strategies are utilized by C1GalT1.

The Golgi apparatus is a highly dynamic organelle which frequently undergoes morphological changes in certain normal physiological processes or in response to stress. The mechanisms are largely not known. We have found that heat shock of Panc1 cells expressing core 2 N-acetylglucosaminyltransferase-M (Panc1-C2GnT-M) induces Golgi disorganization by increasing non-muscle myosin IIA (NMIIA)–C2GnT-M complexes and polyubiquitination and proteasomal degradation of C2GnT-M. These effects are prevented by inhibition or knockdown of NMIIA. Also, the speed of Golgi fragmentation induced by heat shock is found to be positively correlated with the levels of C2GnT-M in the Golgi. The results are reproduced in LNCaP cells expressing high levels of two endogenous glycosyltransferases—core 2 N-acetylglucosaminyltransferase-L:1 and β-galactoside:α2-3 sialyltransferase 1. Further, during recovery after heat shock, Golgi reassembly as monitored by a Golgi matrix protein giantin precedes the return of C2GnT-M to the Golgi. The results are consistent with the roles of giantin as a building block of the Golgi architecture and a docking site for transport vesicles carrying glycosyltransferases. In addition, inhibition/depletion of HSP70 or HSP90 in Panc1-C2GnT-M cells also causes an increase of NMIIA–C2GnT-M complexes and NMIIA-mediated Golgi fragmentation but results in accumulation or degradation of C2GnT-M, respectively. These results can be explained by the known functions of these two HSP: participation of HSP90 in protein folding and HSP70 in protein folding and degradation. We conclude that NMIIA is the master regulator of Golgi fragmentation induced by heat shock or inhibition/depletion of HSP70/90.