Medulloblastoma is the most common malignant brain tumor of childhood. Although the current treatment protocols for this cancer have improved overall survival, they lead to devastating and lifelong sequelae and mortality remains high in recurrent and metastatic disease. Novel targeted therapies are crucial to improve survival in these children without treatment-related toxicity. Medulloblastoma development is largely driven by deregulation of normal cerebellar proliferation wherein aberrant sonic hedgehog (Shh) pathway signaling plays a critical role. Activating mutations of Shh genes are frequent in medulloblastoma and promote their rapid growth. Poor outcomes in Shh-driven tumors have prompted the evaluation of targeted agents against the Shh pathway but these have had limited success - likely due to the upregulation of additional oncogenic pathways including the Ras/MAPK pathway and HIF-1α. These pathways stimulate glycolysis in part by activating the 6-phosphofructo-2-kinase/fructose-2,6 bisphosphatase family of enzymes (PFKFB1-4). The PFKFBs produce fructose-2,6-bisphosphate (F26BP), a potent activator of 6-phosphofructo-1-kinase, a rate-limiting step in glycolysis. We found that the PFKFB4 enzyme is highly expressed in a series of patient-derived medulloblastomas and correlated significantly with expression of the Shh pathway effector Smoothened (SMO). Through HIF-1α upregulation, we observed that hypoxia strongly induced PFKFB4 expression in Shh-active medulloblastoma cells and that silencing PFKFB4 in these cells markedly suppressed F26BP and glycolytic flux to lactate and significantly decreased cell survival and proliferation, more prominently in hypoxia, indicating that PFKFB4 may be preferentially required for survival and growth under hypoxia. We found that co-silencing PFKFB4 and Shh proteins significantly reduced cell survival and that co-targeting PFKFB4 (with a novel small molecule inhibitor) and Shh effectors synergistically decreased cell viability. To mimic Shh antagonist resistance, we subjected Shh medulloblastoma cells to prolonged Shh inhibitor exposure and have found that these cells show increased proliferation and glycolysis and increased expression of PFKFB4 and are more sensitive to PFKFB4 inhibition. Taken together, our data indicate that targeting PFKFB4 may be a valid therapeutic option in aggressive, treatment-resistant medulloblastoma and strongly support the examination of PFKFB4 inhibitors in these tumors.
Thrombotic microangiopathies (TMAs) are a group of rare disorders that can be considered life threatening. The hallmark of this disease is a microangiopathic hemolytic anemia with an associated thrombocytopenia which could be congenital or acquired. Acquired vitamin B12 deficiency is overlooked in developed countries but can mimic a TMA. We report the case of 17-year-old male with malabsorption of vitamin B12 with development of pseudo-TMA. When faced with a clinical presentation of a TMA in a child or an adolescent patient, physicians must be aware of the possibility of vitamin B12 deficiency especially in patients at risk for malabsorption.
Abstract Primary and metastatic breast cancers are driven by oncogenic mutations to rely on glucose metabolism to support their rapid proliferation. Of these genetic changes, the increased activity of the human epidermal growth factor receptor 2 (HER2/ErbB2) is observed in a third of all breast tumors. HER2 has been shown to activate downstream effectors (e.g. Ras, HIF-1α) that stimulate glycolysis - in part by activation of the 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase family of enzymes (PFKFB1-4). The PFKFBs produce fructose-2,6-bisphosphate (F26BP) which activates a key rate-limiting glycolytic enzyme, 6-phosphofructo-1-kinase (PFK1). In preliminary studies, we found that the PFKFB4 family member was highly expressed in a series of patient-derived HER2+ breast tumors relative to normal breast with markedly higher expression in their matched metastatic lymph nodes. We next determined that silencing PFKFB4 markedly reduced F26BP, glycolysis and cell survival in HER2+ breast cancer cells and inhibited tumor growth in vivo. Through virtual screening, we have discovered a first-in-class small molecule inhibitor of PFKFB4, termed 5MPN, that selectively inhibits PFKFB4 activity with a resultant decrease in F26BP, glycolysis and cancer cell growth. 5MPN also caused a significant decrease in the invasion and migration of HER2+ breast cancer cells in vitro, importantly at concentrations well below levels that affect cell viability and marked suppression in the growth of established tumors, without systemic toxicity. In additional studies, we have found that the related PFKFB3 isoform is also expressed in HER+ breast tumors. Our previous work found that the PFKFB4 enzyme localizes to the cytoplasm (where PFK1 and the glycolytic pathway function) indicating a possible dominant role for PFKFB4 in glycolytic regulation. PFKFB3 however largely localized to the nucleus where it serves an important function in proliferation via activation of cyclin-dependent kinases. Based on the different roles played by these enzymes in cancer cells, we next evaluated the effects of simultaneous administration of 5MPN ± a clinical candidate PFKFB3 inhibitor on survival and proliferation in HER2+ breast cancer and found that the combination synergistically and significantly decreased viability and growth in several examined HER2+ breast cancer cell lines. Our data indicate that targeting PFKFB4 may be a viable therapeutic option against breast cancer and strongly support the further exploration of co-targeting PFKFB4 and PFKFB3 as a potential therapeutic strategy for the successful treatment of HER2+ breast cancer. Citation Format: Simone Chang, Jason Chesney, John O. Trent, Sucheta Telang. Targeting glucose metabolism in HER2+breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2519.
A 68-year-old man presented with rhythmic shaking of right-sided extremities that occurred several times per day. The patient appeared confused with incoherent speech. His medical history was significant for West Nile fever diagnosed 8 weeks prior and managed supportively. During that admission, there had been extensive testing that was negative for Human T-Lymphotropic Virus (HTLV), HIV, syphilis or antinuclear antibodies. On examination, there was involuntary myoclonic jerking of the left face, neck and arm (online supplementary video 1). MRI of the brain was notable for leukoaraiosis (figure 1).
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Figure 1
Areas of hyperintense fluid-attenuated inversion recovery (FLAIR)/T2 foci noted in the superficial and deep subcortical white matter of the supratentorium.
Electroencephalography (EEG) showed continuous generalised slowing, suggestive of a moderate diffuse encephalopathy. There was …
Congenital factor V deficiency (FVD) is a rare bleeding disorder. In this study, we investigated the genetic basis in an African American patient with factor V activity 3%. Custom sequence capture and targeted next-generation (NGS) sequencing of the F5 gene were undertaken followed by PCR and Sanger sequencing. Two novel variants were identified. In silico analyses correlated clinically with the patient's factor V activity and hemorrhagic tendency. A review of the literature regarding these genomic alterations is presented. We described two novel mutations causing moderate FVD. The first, Chr1:g.169483698C>A with cDNA change (F5):c.6529-1G>T, occurred in a conserved nucleotide at the canonical acceptor splice site of intron 24. The second, Chr1:g.169515775C>T with cDNA change (F5):c.1667G>A, was a missense variant of exon 11, affecting a highly conserved amino acid in the A2 domain. Further research into the mechanisms of F5 mutations leading to FVD and residual factor V expression are needed.
Sir, Enterococci are facultative anaerobic Gram-positive cocci that very rarely cause lung infections.[1] Even rarer, enterococcal infection can cause empyema.[2] In patients with systemic lupus erythematosus (SLE), empyema due to Salmonella enteritidis, Mycobacterium tuberculosis, and Nocardia asteroides has been reported,[3] but Enterococcus has never been implicated. A 23-year-old female with SLE presented with dyspnea, chest pain, and 2 weeks of fever and productive cough. There were absent breath sounds and dullness to percussion on the right hemithorax; investigations showed anemia, neutrophilia, and thrombocytopenia. Chest radiography confirmed a moderate pleural effusion and a concomitant right-sided pneumothorax. Tube thoracostomy resulted in purulent, malodorous drainage and fluid analysis confirmed empyema. On culture, there was heavy monomicrobial growth of Enterococcus. Despite drainage, the pneumothorax persisted over the next week [Figure 1a]. Computed tomography scanning confirmed persistent collapsed right lung and thickened visceral pleura [Figure 1b], leading to the diagnosis of trapped lung. The patient was treated with antibiotics and pulmonary decortication, with improved symptoms.Figure 1: (a) Chest radiograph and (b) computed tomography scan revealing persistent right-sided pneumothorax with visceral pleural thickeningEnterococcus does not commonly cause pulmonary infection. However, when infection due to Enterococcus does occur, it tends to be complicated.[4] Recently, a case of culture-negative empyema in SLE was described,[5] the first in the literature. However, it was noted that the patient received a dose of levofloxacin before thoracentesis. The second case with a similar diagnosis of sterile empyema in SLE has since been reported, but this patient also received levofloxacin before culture.[3] Grupper et al. have questioned whether enterococcal-associated respiratory infections are underdiagnosed due to the increased use of amoxicillin or fluoroquinolones. Pneumothorax ex-vacuo or trapped lung has been described with complicated parapneumonic effusion. It is thought that chronic inflammation leads to the formation of a fibrous layer on the visceral pleura that prevents re-expansion. Although rare, empyema due to Enterococcus is a potentially life-threatening event in patients with SLE. Physicians must keep in mind this differential, and early thoracentesis with culture before antibiotic therapy is important. Finally, persistent pneumothorax after drainage in these patients must prompt the evaluation for visceral pleural thickening and pneumothorax ex-vacuo. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
