Loss of tumor suppressor KDM6A amplifies PRC2-regulated transcriptional repression in bladder cancer and can be targeted through inhibition of EZH2

Trithorax-like group complex containing KDM6A acts antagonistically to Polycomb-repressive complex 2 (PRC2) containing EZH2 in maintaining the dynamics of the repression and activation of gene expression through H3K27 methylation. In urothelial bladder carcinoma, KDM6A (a H3K27 demethylase) is frequently mutated, but its functional consequences and therapeutic targetability remain unknown. About 70% of KDM6A mutations resulted in a total loss of expression and a consequent loss of demethylase function in this cancer type. Further transcriptome analysis found multiple deregulated pathways, especially PRC2/EZH2, in KDM6A-mutated urothelial bladder carcinoma. Chromatin immunoprecipitation sequencing analysis revealed enrichment of H3K27me3 at specific loci in KDM6A-null cells, including PRC2/EZH2 and their downstream targets. Consequently, we targeted EZH2 (an H3K27 methylase) and demonstrated that KDM6A-null urothelial bladder carcinoma cell lines were sensitive to EZH2 inhibition. Loss- and gain-of-function assays confirmed that cells with loss of KDM6A are vulnerable to EZH2. IGFBP3, a direct KDM6A/EZH2/H3K27me3 target, was up-regulated by EZH2 inhibition and contributed to the observed EZH2-dependent growth suppression in KDM6A-null cell lines. EZH2 inhibition delayed tumor onset in KDM6A-null cells and caused regression of KDM6A-null bladder tumors in both patient-derived and cell line xenograft models. In summary, our study demonstrates that inactivating mutations of KDM6A, which are common in urothelial bladder carcinoma, are potentially targetable by inhibiting EZH2.

Trogocytic CD137 transfer causes an internalization of CD137 ligand on murine APCs leading to reduced T cell costimulation

CD137 ligand (CD137L) is expressed on APCs and crosslinks CD137, a powerful costimulatory molecule on T cells during cognate interactions, and thereby greatly enhances immune responses. We report that CD137 can be transferred from activated T cells and from tumor cells that express CD137 to other cells via trogocytosis. This trogocytic transfer is independent of CD137L expression by the recipient cell. However, if CD137L is present on the recipient cell, the transferred CD137 binds to CD137L and the CD137-CD137L complex becomes internalized. The removal of CD137L from the surface of APCs lowers their ability to costimulate T cells, as evidenced by a reduced IFN-γ secretion. Removal of CD137L on APCs by trogocytic transfer of CD137 occurs within 1 h and requires cell-cell contact and the continuous presence of CD137-expressing cells. Bidirectional signaling exists for the CD137 receptor/ligand system, because CD137L also signals into APCs. We propose that the trogocytic transfer of CD137 from activated T cells to APCs and the subsequent removal of CD137L from APCs is a physiologic regulatory mechanism that limits immune activity. Furthermore, we hypothesize that the trogocytic transfer of CD137 occurs in cancers and quenches the activity of APCs, contributing to the cancer cells escaping immune surveillance. Taken together, our findings demonstrate that the trogocytic transfer of CD137 leads to an internalization of CD137L on APCs and a reduction in immune activity.

CD137 ligand reverse signaling skews hematopoiesis towards myelopoiesis during aging

CD137 is a costimulatory molecule expressed on activated T cells. Its ligand, CD137L, is expressed on the surface of hematopoietic progenitor cells, and upon binding to CD137 induces reverse signaling into hematopoietic progenitor cells promoting their activation, proliferation and myeloid differentiation. Since aging is associated with an increasing number of myeloid cells we investigated the role of CD137 and CD137L on myelopoiesis during aging. Comparing 3 and 12 months old WT, CD137^−/− and CD137L^−/− mice we found significantly more granulocytes and monocytes in the bone marrow of older WT mice, while this age-dependent increase was absent in CD137^−/− and CD137L^−/− mice. Instead, the bone marrow of 12 months old CD137^−/− and CD137L^−/− mice was characterized by an accumulation of hematopoietic progenitor cells, suggesting that the differentiation of hematopoietic progenitor cells became arrested in the absence of CD137L signaling. CD137L signaling is initiated by activated CD137-expressing, CD4⁺ T cells. These data identify a novel molecular mechanisms underlying immune aging by demonstrating that CD137-expressing CD4⁺ T cells in the bone marrow engage CD137L on hematopoietic progenitor cells, and that this CD137L signaling biases hematopoiesis towards myelopoiesis during aging.

Inhibition of proliferation and induction of apoptosis in multiple myeloma cell lines by CD137 ligand signaling

Background

Multiple myeloma (MM) is a malignancy of terminally-differentiated plasma cells, and the second most prevalent blood cancer. At present there is no cure for MM, and the average prognosis is only three to five years. Current treatments such as chemotherapy are able to prolong a patient's life but rarely prevent relapse of the disease. Even hematopoietic stem cell transplants and novel drug combinations are often not curative, underscoring the need for a continued search for novel therapeutics. CD137 and its ligand are members of the Tumor Necrosis Factor (TNF) receptor and TNF superfamilies, respectively. Since CD137 ligand cross-linking enhances proliferation and survival of healthy B cells we hypothesized that it would also act as a growth stimulus for B cell cancers.

Methodology/Principal Findings

Proliferation and survival of B cell lymphoma cell lines were not affected or slightly enhanced by CD137 ligand agonists in vitro. But surprisingly, they had the opposite effects on MM cells, where CD137 ligand signals inhibited proliferation and induced cell death by apoptosis. Furthermore, secretion of the pro-inflammatory cytokines, IL-6 and IL-8 were also enhanced in MM but not in non-MM cell lines in response to CD137 ligand agonists. The secretion of these cytokines in response to CD137 ligand signaling was consistent with the observed activation of the classical NF-κB pathway. We hypothesize that the induction of this pathway results in activation-induced cell death, and that this is the underlying mechanism of CD137-induced MM cell death and growth arrest.

Conclusions/Significance

These data point to a hitherto unrecognized role of CD137 and CD137 ligand in MM cell biology. The selective inhibition of proliferation and induction of cell death in MM cells by CD137 ligand agonists may also warrant a closer evaluation of their therapeutic potential.

EMG myokymia as a cause of ptosis in hypothyroidism

Ptosis is known to be associated with thyroid disorders. We describe two biochemically corrected hypothyroid patients presenting with isolated bilateral ptosis. EMG of the orbicularis oculi showed continuous grouped motor unit potentials. In the absence of obvious aetiology, it is hypothesised that focal demyelination of terminal branches to the orbicularis oculi may play a role in the generation of the discharges.

Two Chinese families with Pendred's syndrome--radiological imaging of the ear and molecular analysis of the pendrin gene

We report two families in whom the index cases satisfied the classical diagnostic criteria of Pendred's syndrome. In family I, two siblings were deaf, and one was normal. In family II, both parents and two offspring were deaf. Computed tomography scans performed in five of six of these deaf individuals showed enlarged vestibular aqueducts in all cases, and Mondini cochlea only in family II. Affected members in family I were compound heterozygotes inheriting the paternal allele with a novel mutation S398del in exon 10 and a maternal allele with two mutations IVS13+9C-->G in intron 13, in addition to H723R. In family II, the mother and one child carried both the novel intronic IVS8-2A-->G and H723R mutations, whereas the father and index case were homozygous for the IVS8-2A-->G mutation. A perchlorate discharge test was positive in 50% of cases tested. In conclusion, we concur that radiological and molecular studies should be performed for confirmation of Pendred's syndrome. We report, for the first time, a Pendred's syndrome family in which affected members had three mutations, as well as a second family in whom the intermarriage of two Pendred's syndrome patients resulted in Pendred's syndrome offspring.

Perioperative management of a patient with congenital myasthenia gravis for elective caesarean section

Congenital disorders of neuromuscular transmission are commonly referred to as congenital myasthenia gravis because of their clinical similarity to the immune-mediated disease. Differentiation between the immune-mediated and congenital forms of the disease is important, because therapy established for the former may not be appropriate for patients with the latter presentation. The course of this rare neuromuscular disorder during pregnancy and its influence on anaesthesia remain largely unknown. We report on the case of a 32-year-old parturient suffering from congenital myasthenia gravis scheduled for elective caesarean section. The perioperative management of this patient who underwent the operation under spinal anaesthesia was reviewed. The effects of anaesthetic agents and techniques on the course of congenital myasthenic patients may need further review in the light of latest findings in the electrophysiology, genetic and therapeutic studies of this syndrome.

Hip fracture incidence rates in Singapore 1991-1998

In this population-based study, we determined the incidence rates of hip fracture among Singapore residents aged 50 years and above. Information was obtained from a centralized database system which captured admissions with the primary diagnosis of a closed hip fracture (ICD-9 codes 820, 820.0, 820.2 and 820.8, n = 12,927) from all health care establishments in the country from 1991 to 1998 inclusive. After removing duplicates, hospital transfers, readmissions and non-acute care admissions, the total number of hip fractures was 9406. Based on the national population census 1990 (n = 464,100) and yearly population estimates, the age-adjusted hip fracture rates for 1991-1998 (per 100,000) were 152 in men and 402 in women. This was 1.5 and over 5 times higher than corresponding rates in the 1960s. From 1991 to 1998, these hip fracture rates tended to increase by 0.7% annually in men and by 1.2% annually in women. Among the three major racial groups, in men, the Chinese had significantly higher age-adjusted hip fracture rates (per 100,000): 168 (95% confidence interval (CI) 158-178) compared with 128 (95% CI 105-152) for Indians and 71 (95% CI 54-88) for Malays. A similar pattern occurred in women: 410 (95% CI 395-425), for Chinese compared with 361 (95% CI 290-432) for Indians and 264 (95% CI 225-303) for Malays. Since the 1960s, the main increases in hip fracture rates have been seen in the Chinese and Malays, with the rates in Indians appearing to decrease. Hip fracture incidence rates in Singapore have risen rapidly over the past 30-40 years, particularly in women, and are now among the highest in Asia. Significant racial differences in hip fracture rates occur within the same community. Time trends in hip fracture rates differed between races.

A simple tool to identify asian women at increased risk of osteoporosis

Patients with low bone mineral density (BMD) have a high risk of future fractures, and should be actively considered for treatment to reduce their risk. However, BMD measurements are not widely available in some communities, because of cost and lack of equipment. Simple questionnaires have been designed to help target high-risk women for BMD measurements, thereby avoiding the cost of measuring women at low risk. However, such tools have previously focused on evaluation of non-Asian women. We collected information about numerous risk factors from postmenopausal Asian women in eight countries in Asia using questionnaires, and evaluated the ability of these risk factors to identify women with osteoporosis as defined by femoral neck BMD T-scores < or =-2.5. Multiple variable regression analysis and item reduction yielded a final tool based on only age and body weight. This risk index had a sensitivity of 91% and specificity of 45%, with an area under the curve of 0.79. Previously published risk indices based on larger numbers of variables performed similarly well in this Asian population. Large differences in risk were identified using our index to create three categories: 61% of the high-risk women had osteoporosis, compared with only 15% and 3% of the intermediate- and low-risk women, respectively. The low-risk group represented 40% of all women, for whom BMD measurements are probably not needed unless important risk factors, such as prior nonviolent fracture or corticosteroid use, are present. An existing population-based sample of postmenopausal Japanese women was used to validate our index. In this sample of Japanese women the sensitivity was 98% and specificity was 29%; the low-risk category, for whom BMD is probably unnecessary, represented 25% of all women. We conclude that our index performed well for classifying the risk of osteoporosis among postmenopausal Asian women and applying it would result in more prudent use of BMD technology.

Interferon-alpha induced thyroid dysfunction: three clinical presentations and a review of the literature

Three patients who developed symptomatic, autoimmune-mediated thyroid dysfunction during treatment with interferon-alpha (IFN-alpha) for chronic active hepatitis C with liver cirrhosis, age-related macular degeneration with foveal involvement, and chronic myelogenous leukemia, respectively, are described. The first two patients developed autoimmune hypothyroidism that required thyroxine replacement, and the third developed autoimmune thyroiditis with transient thyrotoxicosis. The clinical manifestations were protean, and required a high index of suspicion for diagnosis, the failure of which led to significant morbidity. A literature review revealed that the mean incidence of IFN-alpha induced thyroid dysfunction was 6%. Spontaneous resolution occurred in more than half with discontinuation of IFN-alpha treatment. Hypothyroidism was induced more frequently than hyperthyroidism. At least one positive thyroid autoantibody titer was found in 17% of patients receiving IFN-alpha. Risk factors for developing thyroid dysfunction with IFN-alpha treatment were female sex, underlying malignancy or hepatitis C, higher doses of IFN-alpha for longer durations, combination immunotherapy (especially with interleukin-2), and the presence of thyroid autoantibodies prior to or during treatment.

Aldosterone to renin ratios in the evaluation of primary aldosteronism

Primary aldosteronism, though an uncommon cause of hypertension, causes significant morbidity, making it important to diagnose and treat this condition. Its evaluation requires complex and time consuming investigative procedures in order to confirm the diagnosis and to differentiate between the subtypes of aldosterone producing adenoma and idiopathic hyperaldosteronism. Often, the values of renin and aldosterone are equivocal, and the diagnosis of primary aldosteronism is in doubt. In this study, we examine the use of aldosterone to renin ratios in confirming the diagnosis of primary aldosteronism when the usual criteria of suppressed renin and elevated aldosterone are not met. We have found that an aldosterone to renin ratio of 50 has a 100% specificity and 92% sensitivity for detecting primary aldosteronism. Also, an aldosterone to renin ratio of > 2000 is suggestive of an aldosterone producing adenoma.

Thyroid stimulating hormone receptor antibody levels in Singaporean patients with autoimmune thyroid disease

Stimulating thyrotrophin receptor antibodies (TRAbs) have been identified as the antibodies responsible for the pathogenesis of Graves' disease (GD) while blocking TRAbs have been implicated as the cause of hypothyroidism in some patients with chronic lymphocytic thyroiditis (CLT). TRAb positivity in patients with other thyroid disorders such as silent thyroiditis, toxic multinodular goitre and subacute thyroiditis has been reported but the role of TRAb in these disorders is unclear. A study was carried out to determine the prevalence of TRAb positivity in Singaporean patients with a spectrum of thyroid diseases. TRAb levels were measured in 181 patients with GD, 54 patients with CLT (37 goitrous and 17 agoitrous), 16 patients with thyroid nodules, 11 patients with subacute thyroiditis, 1 patient with hyperthyroidism due to a human chorionic gonadotrophin (HCG)-secreting tumour, 2 patients with thyroid stimulating hormone-secreting tumours and 2 patients with amiodarone-induced dysthyroidism. Using a cut-off of 10.0 U/L, TRAb levels were found to be positive in 79.0% of GD patients, 9.2% of CLT patients (euthyroid and hypothyroid) and no patients with other thyroid disorders. TRAb was a more sensitive marker of GD than anti-thyroglobulin antibodies (53.2%) but not anti-microsomal (78.3%) antibodies. TRAb levels > 10.0 U/L appear to be highly specific for autoimmune thyroid disease.

Abnormal thyroid and adrenocortical function test results in intensive care patients

A prospective, cohort study of 75 consecutive patients requiring management in the medical intensive care unit (MICU) of the Singapore General Hospital was carried out over a five-month period to determine thyroid and adrenocortical profiles and evaluate their use in predicting patient outcome. Up to 88% of patients had at least one abnormal thyroid function and 77% had abnormal adrenocortical function test results. There were significantly lower triiodothyronine, thyroxine and free thyroxine, but not thyrotropin levels, and higher cortisol levels in non-survivors compared to survivors (all P < 0.01). Of the endocrine parameters, triiodothyronine and cortisol concentrations were independent predictors of outcome. The overall predictive accuracy of combining these two variables on admission into the MICU was 74%. The APACHE II (acute physiology and chronic health evaluation II) score alone predicted outcome with 71% accuracy, and in combination with triiodothyronine and cortisol levels improved accuracy to 84%. The use of dopamine alone predicted outcome with 74% accuracy, and in combination with triiodothyronine and cortisol levels, improved accuracy to 84%. Measurements of total triiodothyronine and cortisol concentrations on admission to the MICU, and consideration of the use of dopamine improve on the APACHE II score in outcome prediction.

Multiple endocrine neoplasia type two B. A case report with light and electron microscopic and immunohistochemical correlation

PURPOSE

To describe a case of multiple endocrine neoplasia type two B (MEN IIB) where ocular and systemic clinicopathological findings are correlated, in association with light and electron microscopic and immunohistochemical findings.

METHODS

A 23-year-old man presented with mucosal neuromas of the lips, tongue and eyelids, a Marfanoid habitus and prominent corneal nerves. These findings led to the diagnosis of multiple endocrine neoplasia type two B. The patient subsequently developed phaeochromocytoma and metastatic medullary thyroid carcinoma (MTC) which led to his demise. Correlation of light and electron microscopic and immunohistochemical findings with the systemic and ocular findings is presented to emphasise the aggressiveness of MTC in MEN IIB. Clinicopathological correlation was obtained by examining the eyes post mortem.

RESULTS AND CONCLUSIONS

Three new findings in MEN IIB have been established by this study. The enlarged corneal nerves can now be regarded as ganglioneuromas. Medullary thyroid carcinoma metastases were found in the choroid. Light and electron microscopic examination of the eye showed ganglioneuromas of the nerves in the limbus, trabecular meshwork, uveal tract and posterior ciliary nerves; this finding may account for the glaucoma occasionally seen in patients with MEN IIB.