A new approach to the treatment of acute myeloid leukaemia targeting the receptor for growth hormone-releasing hormone.

Growth hormone-releasing hormone (GHRH) is secreted by the hypothalamus and acts on the pituitary gland to stimulate the release of growth hormone (GH). GHRH can also be produced by human cancers, in which it functions as an autocrine/paracrine growth factor. We have previously shown that synthetic antagonistic analogues of GHRH are able to successfully suppress the growth of 60 different human cancer cell lines representing over 20 cancers. Nevertheless, the expression of GHRH and its receptors in leukaemias has never been examined. Our study demonstrates the presence of GHRH receptor (GHRH-R) on 3 of 4 human acute myeloid leukaemia (AML) cell lines-K-562, THP-1, and KG-1a-and significant inhibition of proliferation of these three cell lines in vitro following incubation with the GHRH antagonist MIA-602. We further show that this inhibition of proliferation is associated with the upregulation of pro-apoptotic genes and inhibition of Akt signalling in leukaemic cells. Treatment with MIA-602 of mice bearing xenografts of these human AML cell lines drastically reduced tumour growth. The expression of GHRH-R was further confirmed in 9 of 9 samples from patients with AML. These findings offer a new therapeutic approach to this malignancy and suggest a possible role of GHRH-R signalling in the pathology of AML.

A Case of AML Characterized by a Novel t(4;15)(q31;q22) Translocation That Confers a Growth-Stimulatory Response to Retinoid-Based Therapy.

Here we report the case of a 30-year-old woman with relapsed acute myeloid leukemia (AML) who was treated with all-trans retinoic acid (ATRA) as part of investigational therapy (NCT02273102). The patient died from rapid disease progression following eight days of continuous treatment with ATRA. Karyotype analysis and RNA-Seq revealed the presence of a novel t(4;15)(q31;q22) reciprocal translocation involving the TMEM154 and RASGRF1 genes. Analysis of primary cells from the patient revealed the expression of TMEM154-RASGRF1 mRNA and the resulting fusion protein, but no expression of the reciprocal RASGRF1-TMEM154 fusion. Consistent with the response of the patient to ATRA therapy, we observed a rapid proliferation of t(4;15) primary cells following ATRA treatment ex vivo. Preliminary characterization of the retinoid response of t(4;15) AML revealed that in stark contrast to non-t(4;15) AML, these cells proliferate in response to specific agonists of RARα and RARγ. Furthermore, we observed an increase in the levels of nuclear RARγ upon ATRA treatment. In summary, the identification of the novel t(4;15)(q31;q22) reciprocal translocation opens new avenues in the study of retinoid resistance and provides potential for a new biomarker for therapy of AML.

Clinical Responsiveness to All-trans Retinoic Acid Is Potentiated by LSD1 Inhibition and Associated with a Quiescent Transcriptome in Myeloid Malignancies.

PURPOSE: In preclinical studies, the lysine-specific histone demethylase 1A (LSD1) inhibitor tranylcypromine (TCP) combined with all-trans retinoic acid (ATRA) induces differentiation and impairs survival of myeloid blasts in non-acute promyelocytic leukemia acute myeloid leukemia (AML). We conducted a phase I clinical trial (NCT02273102) to evaluate the safety and activity of ATRA plus TCP in patients with relapsed/refractory AML and myelodysplasia (MDS). PATIENTS AND METHODS: Seventeen patients were treated with ATRA and TCP (three dose levels: 10 mg twice daily, 20 mg twice daily, and 30 mg twice daily). RESULTS: ATRA-TCP had an acceptable safety profile. The MTD of TCP was 20 mg twice daily. Best responses included one morphologic leukemia-free state, one marrow complete remission with hematologic improvement, two stable disease with hematologic improvement, and two stable disease. By intention to treat, the overall response rate was 23.5% and clinical benefit rate was 35.3%. Gene expression profiling of patient blasts showed that responding patients had a more quiescent CD34+ cell phenotype at baseline, including decreased MYC and RARA expression, compared with nonresponders that exhibited a more proliferative CD34+ phenotype, with gene expression enrichment for cell growth signaling. Upon ATRA-TCP treatment, we observed significant induction of retinoic acid-target genes in responders but not nonresponders. We corroborated this in AML cell lines, showing that ATRA-TCP synergistically increased differentiation capacity and cell death by regulating the expression of key gene sets that segregate patients by their clinical response. CONCLUSIONS: These data indicate that LSD1 inhibition sensitizes AML cells to ATRA and may restore ATRA responsiveness in subsets of patients with MDS and AML.

Ex-vivo sensitivity profiling to guide clinical decision making in acute myeloid leukemia: A pilot study.

A precision medicine approach is appealing for use in AML due to ease of access to tumor samples and the significant variability in the patients' response to treatment. Attempts to establish a precision medicine platform for AML, however, have been unsuccessful, at least in part due to the use of small compound panels and having relatively slow turn over rates, which restricts the scope of treatment and delays its onset. For this pilot study, we evaluated a cohort of 12 patients with refractory AML using an ex vivo drug sensitivity testing (DST) platform. Purified AML blasts were screened with a panel of 215 FDA-approved compounds and treatment response was evaluated after 72h of exposure. Drug sensitivity scoring was reported to the treating physician, and patients were then treated with either DST- or non-DST guided therapy. We observed survival benefit of DST-guided therapy as compared to the survival of patients treated according to physician recommendation. Three out of four DST-treated patients displayed treatment response, while all of the non-DST-guided patients progressed during treatment. DST rapidly and effectively provides personalized treatment recommendations for patients with refractory AML.

Muc4/sialomucin complex, the intramembrane ErbB2 ligand, in cancer and epithelia: to protect and to survive.

The membrane mucin Muc4, also called sialomucin complex (SMC), is a heterodimeric complex of two subunits, ASGP-1 and ASGP-2, derived from a single gene. It is produced by multiple epithelia in both membrane and soluble forms and serves as a protective agent for the epithelia. The membrane form of Muc4 acts as a steric barrier to the apical cell surface of epithelial or tumor cells. An important example is the uterus of the rat, in which Muc4 expression is downregulated for blastocyst implantation. The soluble form facilitates the protection and lubrication of epithelia by mucous gels composed of gel-forming mucins, as in the airway, where Muc4 is proposed to participate in mucociliary transport as a constituent of the periciliary fluid. The soluble form is also found in body fluids, such as milk, tears, and saliva. The transmembrane subunit ASGP-2 acts as an intramembrane ligand and activator for the receptor tyrosine kinase ErbB2. Formation of this ligand-receptor complex is proposed to repress apopotosis in epithelial and cancer cells in which the ligand-receptor complex is formed, providing a second type of cell protective mechanism. Muc4 expression is regulated in epithelial tissues in a cell- and tissue-specific manner during epithelial differentiation. In stratified epithelia, it is predominantly in the most superficial, differentiated layers, often coincident with ErbB2. Dysregulation of Muc4 expression may contribute to cell and tissue dysfunction, such as the proposed contribution of Muc4 to mammary tumor progression. These observations clearly show that Muc4 has multiple roles in epithelia, which may provide insights into aberrant behaviors of these tissues and their derivative carcinomas.

Risk Stratification System for Oral Cancer Screening.

Oral cavity and oropharyngeal cancer (oral cancer) is a deadly disease that is increasing in incidence. Worldwide 5-year survival is only 50% due to delayed intervention with more than half of the diagnoses at stage III and IV, whereas earlier detection (stage I and II) yields survival rates up to 80% to 90%. Salivary soluble CD44 (CD44), a tumor-initiating marker, and total protein levels may facilitate oral cancer risk assessment and early intervention. This study used a hospital-based design with 150 cases and 150 frequency-matched controls to determine whether CD44 and total protein levels in oral rinses were associated with oral cancer independent of age, gender, race, ethnicity, tobacco and alcohol use, and socioeconomic status (SES). High-risk subjects receiving oral cancer prevention interventions as part of a community-based program (n = 150) were followed over 1 year to determine marker specificity and variation. CD44 ≥5.33 ng/mL was highly associated with case status [adjusted OR 14.489; 95% confidence interval (CI), 5.973-35.145; P < .0001, vs. reference group CD44 <2.22 ng/mL and protein <1.23 mg/mL]. Total protein aided prediction above CD44 alone. Sensitivity and specificity in the frequency-matched study was 80% and 48.7%, respectively. However, controls were not representative of the target screening population due, in part, to a high rate of prior cancer. In contrast, specificity in the high-risk community was 74% and reached 95% after annual retesting. Simple and inexpensive salivary CD44 and total protein measurements may help identify individuals at heightened risk for oral cancer from the millions who partake in risky behaviors. Cancer Prev Res; 9(6); 445-55. ©2016 AACR.

CD44 interacts with EGFR and promotes head and neck squamous cell carcinoma initiation and progression.

OBJECTIVES: CD44 is a promising target for therapy in head and neck squamous cell carcinoma (HNSCC) and has two defined roles in tumorigenesis: it is a cancer stem cell (CSC) marker and it promotes migration and proliferation through interaction with many signaling molecules. The purpose of this study was to investigate the role of CD44 in HNSCC carcinogenesis. MATERIALS AND METHODS: The effects of CD44 in cell proliferation, migration, apoptosis and cisplatin resistance were studied by its overexpression in HNSCC cells. We also evaluated the effect of CD44 on tumor progression by siRNA methodology, immunohistochemistry (IHC) and western blot analysis. CD44 and EGFR colocalization were examined in CAL 27 cells by laser scanning confocal microscopy. The interaction between CD44 and EGFR was analyzed by immunoprecipation. RESULTS: Overexpression of CD44 enhances cell proliferation and migration and correlates with increased cisplatin resistance and apoptosis inhibition in SCC25 cells. Downregulation of CD44 in CAL27 cells inhibited constitutive EGFR phosphorylation and significantly reduced tumor growth in nude mice. CD44 and EGFR colocalized in CAL 27 cells. CD44 coimmunoprecipated with EGFR in CAL 27 cells, indicating that these proteins interact with each other. CONCLUSION: CD44 therapy in HNSCC may target the CSC population and alter EGFR signaling.

Salivary markers and risk factor data: a multivariate modeling approach for head and neck squamous cell carcinoma detection.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) is a debilitating and deadly disease largely due to late stage diagnosis. Prior work indicates that soluble CD44 (solCD44) and total protein may be useful diagnostic markers for HNSCC. In this study we combine the markers solCD44, IL-8, HA, and total protein with demographic and risk factor data to derive a multivariate logistic model that improves HNSCC detection as compared to our previous data using biomarkers alone. METHODS: We performed the solCD44, IL-8, HA, and total protein assays on oral rinses from 40 HNSCC patients and 39 controls using ELISA assays. Controls had benign diseases of the upper aerodigestive tract and a history of tobacco or alcohol use. All subjects completed a questionnaire including demographic and risk factor data. RESULTS: Depending on cancer subsite, differences between cases and controls were found for all markers. A multivariate logistic model including solCD44, total protein and variables related to smoking, oral health and education offered a significant improvement over the univariate models with an AUC of 0.853. Sensitivity ranged from 75-82.5% and specificity from 69.2-82.1% depending on predictive probability cut points. CONCLUSION: A multivariate model, including simple and inexpensive molecular tests in combination with risk factors, results in a promising tool for distinguishing HNSCC patients from controls. IMPACT: In this case-control study, the resulting observations led to an unprecedented multivariate model that distinguished HNSCC cases from controls with better accuracy than the current gold standard which includes oral examination followed by tissue biopsy. Since the components are simple, noninvasive, and inexpensive to obtain, this model combining biomarkers, risk factor and demographic data serves as a promising prototype for future cancer detection tests.

Presence of MUC4 in human milk and at the luminal surfaces of blood vessels.

MUC4 is a heterodimeric membrane mucin, composed of a mucin subunit ASGP-1 (MUC4alpha) and a transmembrane subunit ASGP-2 (MUC4beta), which has been implicated in the protection of epithelial cell surfaces. Surprisingly, development and characterization of a new monoclonal antibody (mAb), called 1G8, against ASGP-2 demonstrated by immunohistochemistry the presence of MUC4 at the luminal surfaces of blood vessels of both normal tissues and tumors. Muc4 was detected with 1G8 and other Muc4 antibodies in blood vessels from humans, rats and mice. This expression of MUC4 in endothelial cells was confirmed by immunoblotting with 1G8 in human umbilical vein endothelial cells (HUVECs), human iliac artery endothelial cells (HIAECs), and human microvascular endothelial cells (HMVECs). MUC4 could be observed on HUVECs grown on either plastic or Matrigel. Finally, MUC4 expression in the three types of endothelial cell lines was confirmed by reverse transcription-polymerase chain reaction (RT-PCR). These results provide, to our knowledge, the first demonstration of a member of the MUC gene family and membrane mucin in blood vessels. As a luminal surface component, the MUC4 is situated to contribute to the non-adhesive luminal surface and to act as an intrinsic protection and survival factor.

PEA3 transactivates the Muc4/sialomucin complex promoter in mammary epithelial and tumor cells.

Sialomucin complex (SMC, rat Muc4) is a heterodimeric glycoprotein composed of two subunits, the mucin component ascites sialoglycoprotein ASGP-1 and the transmembrane subunit ASGP-2, which is aberrantly expressed on the surfaces of a variety of tumor cells. Up-regulation of the Muc4/SMC gene in the 13762 sublines of the rat mammary adenocarcinoma correlates with the overexpression of transcription factor PEA3 and the receptor tyrosine kinase ErbB2. Here we report that PEA3 is capable of transactivating the Muc4/SMC promoter in a dose-dependent manner via direct attachment to a PEA3 binding site. ERM and ER81, the other two members of the PEA3 subfamily of transcription factors, could not transactivate the Muc4/SMC promoter. Transcriptional activation of Muc4/SMC by PEA3 is potentiated by Ras and MEKK1 kinases. These data suggest that expression of PEA3 in mammary tumors leads to up-regulation of Muc4/SMC transcription, the gene product of which may contribute to the metastatic potential of mammary tumors.