Pathological features of Gleason score 6 prostate cancers in the low and intermediate range of prostate‐specific antigen level: is there a difference?

OBJECTIVE

To assess the pathological features of Gleason score 6 prostate cancers after radical prostatectomy in the low (<4 ng/mL) and intermediate range of prostate‐specific antigen level (4–10 ng/mL), as such prostate cancers are considered to be well differentiated tumours with a low risk for recurrence after therapy.

PATIENTS AND METHODS

In all, 1354 patients with T1c prostate cancer and PSA levels of <10.0 ng/mL had a radical retropubic prostatectomy. Patients with Gleason score 6 tumours were divided into two groups, those with PSA levels of <4 and 4.0–10.0 ng/mL. Extracapsular extension, positive surgical margins, biochemical recurrence (BCR) and mean time to BCR were evaluated.

RESULTS

Of the 1354 patients, there were 437 (32.3%) with Gleason score 6 prostate cancers. Patients in the low PSA group had less extraprostatic disease than those with a higher level (5.9% vs 14.5%) and both groups had an almost equal proportion of positive surgical margins (9.4% vs 11.0%). In the low PSA group there was statistically significantly shorter BCR than in the high PSA group, with a mean time to BCR of 1.7 vs 3.1 years.

CONCLUSIONS

These results show a statistically significantly higher rate of extraprostatic disease and earlier BCR in men with a high than a low PSA level even in Gleason score 6 prostate cancer. As the rate of BCR and extracapsular extension are significantly related to prostate cancer mortality, these findings further support the concept of screening using low PSA levels.     

Growth of Mycobacterium tuberculosis at acidic pH depends on lipid assimilation and is accompanied by reduced GAPDH activity

Acidic pH arrests the growth of Mycobacterium tuberculosis in vitro (pH < 5.8) and is thought to significantly contribute to the ability of macrophages to control M. tuberculosis replication. However, this pathogen has been shown to survive and even slowly replicate within macrophage phagolysosomes (pH 4.5 to 5) [M. S. Gomes et al., Infect. Immun. 67, 3199–3206 (1999)] [S. Levitte et al., Cell Host Microbe 20, 250–258 (2016)]. Here, we demonstrate that M. tuberculosis can grow at acidic pH, as low as pH 4.5, in the presence of host-relevant lipids. We show that lack of phosphoenolpyruvate carboxykinase and isocitrate lyase, two enzymes necessary for lipid assimilation, is cidal to M. tuberculosis in the presence of oleic acid at acidic pH. Metabolomic analysis revealed that M. tuberculosis responds to acidic pH by altering its metabolism to preferentially assimilate lipids such as oleic acid over carbohydrates such as glycerol. We show that the activity of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is impaired in acid-exposed M. tuberculosis likely contributing to a reduction in glycolytic flux. The generation of endogenous reactive oxygen species at acidic pH is consistent with the inhibition of GAPDH, an enzyme well-known to be sensitive to oxidation. This work shows that M. tuberculosis alters its carbon diet in response to pH and provides a greater understanding of the physiology of this pathogen during acid stress.

Tuberculosis (TB) is a chronic disease mostly affecting the lungs and, despite the availability of a vaccine and antibiotic therapy, remains the leading cause of death due to a single bacterium. An estimated 2 billion people are thought to be infected with Mycobacterium tuberculosis, the causative agent of TB, with 10 million new infections each year and 1 million deaths (1). M. tuberculosis success as a pathogen can be attributed to its ability to adapt and persist within the host. This intracellular pathogen replicates within macrophages and must be able to withstand host-imposed stresses as well as gain access to nutrients to survive and proliferate. M. tuberculosis has been observed inside lipid-rich lesions during infection in humans and in animal models of TB (2, 3). Its genome contains an extensive number of redundant genes dedicated to β-oxidation necessary for lipid breakdown, indicating the importance of lipid catabolism (4). In addition to β-oxidation, lipid utilization depends on two key enzymes, isocitrate lyase (ICL) required for the glyoxylate shunt and phosphoenolpyruvate carboxykinase (PEPCK) catalyzing the first committed step of gluconeogenesis. Mutants lacking either ICL or PEPCK cannot grow with lipids as a sole carbon source and are severely attenuated in the TB mouse model (5–7). While M. tuberculosis can simultaneously use several different carbon sources to grow in vitro (8), lipids seem to be the primary source of carbon during infection (5, 7, 9–11). Whether this is because glycolytic carbon sources are scarce or inaccessible or because M. tuberculosis requires lipids to grow during infection is unknown.Despite its ability to block phagosome–lysosome fusion, a notable fraction of phagocytosed M. tuberculosis is rapidly trafficked toward acidified compartments, and this proportion increases upon macrophage activation by T cell produced interferon-γ (IFN-γ) (12–14). Moreover, lung tissues from TB patients were found to have a median pH of pH 5.5 (15) supporting that M. tuberculosis faces acid stress during its infectious cycle in humans. M. tuberculosis can survive at a pH as low as pH 4.5 by maintaining its intracellular pH close to neutral at least in part through sustained peptidoglycan hydrolysis (16, 17). While the identification of mechanisms that enable M. tuberculosis to survive at acidic pH has taken much attention, how the pathogen adapts to an acidified environment to grow and promote disease remains ill defined. At acidity lower than pH 5.8, M. tuberculosis enters a nonreplicating state in vitro (18). This growth arrest at mildly acidic pH is surprising considering that the bacterium likely replicates in more acidic environments during infection.The media used to culture mycobacteria contain glycerol and glucose as main carbon sources. Previous work demonstrated that growth of M. tuberculosis at acidic pH is improved by changing the carbon source (18, 19). Pyruvate promoted growth of M. tuberculosis at pH 5.7 (19) indicating that growth at acidic pH is regulated by available carbon sources. Because lipids appear to be the primary carbon source M. tuberculosis utilizes to grow in vivo (5, 7, 9–11), we hypothesized that providing host-relevant carbon sources to M. tuberculosis, such as lipids, would serve as a more physiologically relevant model to examine how M. tuberculosis responds to acidic pH. Here, we demonstrate that providing oleic acid (OA) (and other host-relevant lipids) as a carbon source to M. tuberculosis, resulted in sustained growth in acidic cultures at pH 5.5 and below. We applied metabolomics, genetic, and biochemical approaches to investigate this pH-driven use of lipids to support growth. Our work helps explain the dependence of M. tuberculosis on lipids as a primary carbon source during infection and demonstrates that M. tuberculosis is well adapted to the acidic environments it encounters during infection; in fact, it is not only able to maintain its neutral intrabacterial pH, as previously reported, but can replicate in acidic conditions similar to those within phagolysosomes.     

GlialCAM, an immunoglobulin-like cell adhesion molecule is expressed in glial cells of the central nervous system

Using structure based genome mining targeting vascular endothelial and platelet derived growth factor immunoglobulin (Ig) like folds, we have identified a sequence corresponding to a single transmembrane protein with two Ig domains, which we cloned from a human brain cDNA library. The cDNA is identical to hepatocyte cell adhesion molecule (hepaCAM), which was originally described as a tumor suppressor gene in liver. Here, we show that the protein is predominantly expressed in the mouse and human nervous system. In liver, the expression is very low in humans, and is not detected in mice. To identify the central nervous system (CNS) regions and cell types expressing the protein, we performed a LacZ reporter gene assay on heterozygous mice in which one copy of the gene encoding the novel protein had been replaced with beta-galactosidase. beta-galactosidase expression was prominent in white matter tracts of the CNS. Furthermore, expression was detected in ependymal cells of the brain ventricular zones and the central canal of the spinal cord. Double labeling experiments showed expression mainly in CNPase positive oligodendrocytes (OL). Since the protein is predominantly expressed in the CNS glial cells, we named the molecule glial cell adhesion molecule (GlialCAM). A potential role for GlialCAM in myelination was supported by its up-regulation during postnatal mouse brain development, where it was concomitantly expressed with myelin basic protein (MBP). In addition, in vitro, GlialCAM was observed in various developmental stages of OL and in astrocytes in processes and at cell contact sites. In A2B5 positive OL, GlialCAM colocalizes with GAP43 in OL growth cone like structures. Overall, the data presented here indicate a potential function for GlialCAM in glial cell biology.     

Leukemic blasts in transformed JAK2-V617F-positive myeloproliferative disorders are frequently negative for the JAK2-V617F mutation

To study the role of the JAK2-V617F mutation in leukemic transformation, we examined 27 patients with myeloproliferative disorders (MPDs) who transformed to acute myeloid leukemia (AML). At MPD diagnosis, JAK2-V617F was detectable in 17 of 27 patients. Surprisingly, only 5 of 17 patients developed JAK2-V617F-positive AML, whereas 9 of 17 patients transformed to JAK2-V617F-negative AML. Microsatellite analysis in a female patient showed that mitotic recombination was not responsible for the transition from JAK2-V617F-positive MPD to JAK2-V617F-negative AML, and clonality determined by the MPP1 polymorphism demonstrated that the granulocytes and leukemic blasts inactivated the same parental X chromosome. In a second patient positive for JAK2-V617F at transformation, but with JAK2-V617F-negative leukemic blasts, we found del(11q) in all cells examined, suggesting a common clonal origin of MPD and AML. We conclude that JAK2-V617F-positive MPD frequently yields JAK2-V617F-negative AML, and transformation of a common JAK2-V617F-negative ancestor represents a possible mechanism.     

Inhibition of Dll4-mediated signaling induces proliferation of immature vessels and results in poor tissue perfusion

Vascular development is dependent on various growth factors and certain modifiers critical for providing arterial or venous identity, interaction with the surrounding stroma and tissues, hierarchic network formation, and recruitment of pericytes. Notch receptors and ligands (Jagged and Delta-like) play a critical role in this process in addition to VEGF. Dll4 is one of the Notch ligands that regulates arterial specification and maturation events. In the current study, we have shown that loss of function by either targeted allele deletion or use of a soluble form of Dll4 extracellular domain leads to inhibition of Notch signaling, resulting in increased vascular proliferation but defective maturation. Newly forming vessels have thin caliber, a markedly reduced vessel lumen, markedly reduced pericyte recruitment, and deficient vascular perfusion. sDll4 similarly induced defective vascular response in tumor implants leading to reduced tumor growth. Interference with Dll4-Notch signaling may be particularly desirable in tumors that have highly induced Dll4-Notch pathway.     

ECOG performance status 0 or 1 and symptom classification do not improve the ability to predict renal cell carcinoma-specific survival

ObjectivesWe tested and compared the improvement in prognostic ability related to the consideration of either ECOG performance status (ECOGPS) and/or symptom classification (S-CLASS) in renal cell carcinoma specific mortality (RCC-SM) predictions.MethodsUnivariate and multivariate Cox regression analyses targeted RCC-SM in 2570 RCC patients treated with either partial or radical nephrectomy. The increment in predictive accuracy related to the addition of either ECOGPS, S-CLASS or both was quantified using Harrell’s concordance index.ResultsFollow-up ranged from 0.1 to 23 years (median 3.2) and 610 patients (23.7%) died of RCC. In multivariable analyses, ECOGPS and S-CLASS represented independent predictors of RCC-SM. The addition of ECOGPS to established RCC-SM predictors increased the predictive accuracy by 0.3% (p = 0.8) versus 0.6% (p = 0.5) for S-CLASS versus 0.6% (p = 0.5) for both.ConclusionsNeither ECOGPS nor S-CLASS improves the ability to predict RCC-SM. Therefore, these variables may be safely omitted when RCC-SM risk is quantified.