Loss of LARGE2 disrupts functional glycosylation of α-dystroglycan in prostate cancer

Dystroglycan (DG) is a cell surface receptor for extracellular matrix proteins and is involved in cell polarity, matrix organization, and mechanical stability of tissues. Previous studies documented loss of DG protein expression and glycosylation in a variety of cancer types, but the underlying mechanisms and the functional consequences with respect to cancer progression remain unclear. Here, we show that the level of expression of the βDG subunit as well as the glycosylation status of the αDG subunit inversely correlate with the Gleason scores of prostate cancers; furthermore, we show that the functional glycosylation of αDG is substantially reduced in prostate cancer metastases. Additionally, we demonstrate that LARGE2 (GYLTL1B), a gene not previously implicated in cancer, regulates functional αDG glycosylation in prostate cancer cell lines; knockdown of LARGE2 resulted in hypoglycosylation of αDG and loss of its ability to bind laminin-111 while overexpression restored ligand binding and diminished growth and migration of an aggressive prostate cancer cell line. Finally, our analysis of LARGE2 expression in human cancer specimens reveals that LARGE2 is significantly down-regulated in the context of prostate cancer, and that its reduction correlates with disease progression. Our results describe a novel molecular mechanism to account for the commonly observed hypoglycosylation of αDG in prostate cancer.

Abstract 439: Glycosylation of α-dystroglycan in prostate cancer: Prognostic implications and regulation by LARGE2

Cancer cells exhibit altered interactions with their extracellular matrix microenvironment that are thought to underlie tumor progression and metastasis. Dystroglycan (DG) is a receptor for extracellular matrix proteins including laminins and perlecan that consists of a ligand-binding α subunit and a transmembrane β subunit. DG protein expression is reduced in numerous types of cancer, including prostate cancer. Typically DG mRNA expression is not remarkably altered and mutations in the DG gene have not been reported in any cancer to date. We have investigated the basis for reduced DG expression in prostate cancer. Using tissue microarray (n=50; Gleason score 6-8) we show that loss of either α or β DG independently predicts Gleason score. We show that loss of αDG immunostaining in human prostatectomy samples (n=138) trended towards predicting overall mortality independent of grade and stage with an estimated hazard ratio of 1.32 (CI=0.92, 1.89; p=0.1381). Furthermore, analysis of prostate cancer metastases in bone, lung and lymph node shows a near universal loss of αDG immunostaining. Importantly, we observed cases in which αDG is reduced while βDG persisted in serial sections, suggesting that these subunits may be differentially affected. In these studies, we detected αDG using a glycosylation-sensitive antibody IIH6. Therefore, we investigated the basis of altered αDG glycosylation using a series of prostate cancer cell lines. We found that αDG glycosylation is heterogeneous across several prostate cancer cell lines. Importantly, we found that an aggressive derivative of PC-3 cells lacks IIH6 immunoreactivity, but not core αDG protein expression; whereas the bulk PC-3 population is IIH6 positive. We evaluated the relative expression of a panel of glycosyltransferases known to modify αDG in these cell lines and found that loss of IIH6 immunoreactivity is correlated with loss of LARGE2 expression. This result contrasts with previous findings implicating LARGE or iGNT with abnormal glycosylation of αDG in breast and prostate cancer respectively. Reduced expression of LARGE2 is also observed in pancreatic cancer cell lines and is correlated with loss of IIH6 immunoreactivity. We show that LARGE2 is involved in the functional glycosylation of αDG in prostate cancer cells. shRNA-mediated knockdown of LARGE2 in prostate cancer cells does not affect growth rate, but does increase transwell migration across laminin-1 substrate. Our results are the first to implicate loss of LARGE2 expression as a means to explain the loss of appropriate glycosylation of αDG in prostate or other cancers, and indicates that LARGE2 function may modulate prostate cancer progression and metastasis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 439. doi:1538-7445.AM2012-439

Adhesive temperature: effects on adhesive properties and resin-dentin bond strength

OBJECTIVES

To evaluate the effect of adhesive temperature on the resin-dentin bond strength (μTBS), nanoleakage (NL), adhesive layer thickness (AL), and degree of conversion (DC) of ethanol/water- (SB) and acetone-based (PB) etch-and-rinse adhesive systems.

METHODS

The bottles of the two adhesives were kept at each temperature (5°C, 20°C, 37°C, and 50°C) for 2 hours before application to demineralized dentin surfaces of 40 molars. Specimens were prepared for μTBS testing. Bonded sticks (0.8 mm(2)) were tested under tension (0.5 mm/min). Three bonded sticks from each tooth were immersed in silver nitrate and analyzed by scanning electron microscopy. The DC of the adhesives was evaluated by Fourier transformed infrared spectroscopy.

RESULTS

Lower μTBS was observed for PB at 50°C. For SB, the μTBS values were similar for all temperatures. DC was higher at 50°C for PB. Higher NL and thicker AL were observed for both adhesives in the 5°C and 20°C groups compared to the 37°C and 50°C groups. The higher temperatures (37°C or 50°C) reduced the number of pores within the adhesive layer of both adhesive systems.

CONCLUSIONS

It could be useful to use an ethanol/water-based adhesive at 37°C or 50°C and an acetone-based adhesive at 37°C to improve adhesive performance.

Abstract 421: Dystroglycan glycosylation status predicts Gleason grade and influences prostate tumor growth

Dystroglycan, an extracellular matrix receptor, is expressed in many tissues including muscle, neural, adipose and epithelial where its function includes roles in polarity, basement membrane formation and tissue morphogenesis. Loss of dystroglycan expression has been shown in many epithelial cancers including prostate cancer yet the underlying mechanism remains unclear. Here, we investigate the role of DG in prostate cancer progression. We show that staining for the extracellular αDG subunit with the glycosylation-sensitive IIH6 anti-αDG antibody as well as the transmembrane βDG subunit are independent predictors of Gleason score in clinical prostate cancer specimens. In addition, increased αDG glycosylation due to expression of LARGE, a putative glycosyltransferase, in prostate cancer cell lines results in decreased tumor growth in prostate cancer xenografts. We determined that this reduction in growth is specific to the effect of LARGE on dystroglycan. Therefore our work has shown that the extent of αDG glycosylation predicts Gleason scores in prostate cancer and that LARGE dependent glycosylation of αDG regulates tumor growth.

This work is supported by a grant from the National Institutes of Health R01-CA130916

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 421.

Surgically discovered xanthogranulomatous pyelonephritis invading inferior vena cava with coexisting renal cell carcinoma

Xanthogranulomatous pyelonephritis (XGP) is a chronic inflammatory process that results in replacement of renal and/or perirenal tissue with a diffuse infiltrate of inflammatory cells referred to as xanthoma cells. We present a case of a 49-year-old man with an incidentally discovered renal mass with inferior vena cava (IVC) thrombus, who was found intraoperatively to have a significant inflammatory process involving the posterior wall of his IVC and right renal vein consistent with XGP surrounding a focus of clear cell renal cell carcinoma in the midportion of his right kidney.

Determination of charge states of single swift heavy projectiles by high-energy delta-electrons

The effective charge state is an important particle parameter which is required for the calculation of many effects concerning the interaction between radiation and matter such as an estimate of the radial dose of swift heavy projectiles, stopping power and so on. A new method for the determination of effective charge states of heavy ions is based on the measurement of the number of high-energy delta-electrons which are ejected from a target by the penetrating ion. These electrons are detectable with a CCD-detector and their number can be correlated to the effective charge state of the projectile for known particle velocities. This method is even applicable to operation with single swift heavy ions within statistical bounds.

The development of auditory event related potentials in the rhesus monkey (Macaca mulatta)

Auditory event related potentials were recorded from neonatal, 3-month, and 3-year old rhesus monkeys. Auditory brainstem evoked responses (ABRs) were reliably recorded at all ages. ABR latencies decreased with age. Age effects were greater the more centrally generated the wave. Wave I amplitude decreased with age, Wave II increased, and Wave IV remained about the same. Stimulus rate effects were greater in neonates than older monkeys. Stimulus frequency also affected the ABR, but not differentially as a function of age. Recording montage had a significant effect on the recorded waveform. Wave I tended to be larger in amplitude in horizontal recordings and front-back recordings, while the later waves were relatively more prominent in more vertical montages. Middle latency evoked responses and late potentials were less reliably recorded than the ABR. Their reproducibility improved with age. Auditory event related potentials are promising measures of auditory function for research requiring nonhuman primate models of the developing human.

The changing image of Catholic women

The characteristics of Roman Catholic women in today's society were investigated. Subjects were 154 Catholic women, both religious and lay, who participated on a volunteer basis. The Catholic lay women (111) were divided into two groups: those who attended a Catholic elementary school (63) and those who attended a non-Catholic elementary school (48). Catholic women religious were found to be more dominant and independent minded than in previous research. All of the women studied were found to be more aggressive and more critical of authority than in previous studies. Likewise, Catholic women no longer see themselves in the role of nurturers.