Abstract 1227: Immune modulatory effect of pramlintide for cutaneous squamous cell carcinoma treatment

Cutaneous squamous cell carcinoma (cuSCC) accounts for 15-20% of skin cancers. Treatment of cuSCC with pramlintide, a synthetic analog of the hormone amylin, is currently under investigation in mouse models and human clinical trials. In cancer cells, pramlintide inhibits glycolysis, resulting in cell death and tumor regression. In order to investigate the potential use of pramlintide in combinatory therapies with checkpoint inhibitors, we aimed to study the immune modulatory effect of pramlintide in an immune competent mouse model of spontaneous ultraviolet radiation-induced cuSCC, as well as its effect on human T cells in vitro. To induce cuSCC, SKH-1 hairless mice were subjected to ultraviolet radiation until at least one tumor reached >4mm of diameter. Mice were then treated with 45 µg/kg of pramlintide or vehicle control for 10 days, every other day. Skin-draining lymph nodes, spleen and tumors were harvested for immunophenotyping of the T cell and myeloid compartment by flow cytometry. While the proportion of CD103+ dendritic cells (DCs) and CD3+ T cells remained constant after pramlintide treatment, a significant decrease in the proportion of both monocytic and granulocytic myeloid-derived suppressor cells (m-MDSCs and g-MDSCs) was observed relative to vehicle-control treated mice. Interestingly, pramlintide abolished m-MDSC differentiation from bone marrow progenitors in vitro suggesting that pramlintide may regulate a pathway necessary for m-MDSC development. Purified human CD3+ T cells activated in the presence of pramlintide exhibited a time-dependent increase in intracellular and secreted IFN-γ. Therefore, pramlintide may have immune modulatory effects based on both a reduction in myeloid-dependent suppression and a direct stimulatory effect on T cells that would culminate in superior anti-tumor T cell responses that augment immunotherapeutic approaches for the treatment of cuSCC.

Citation Format: Leticia Tordesillas, Rebecca Hesterberg, Ivannie Ortiz-Rivera, Brittney R. Sell, Omar Chavez Chiang, Kimberly T. Nguyen, Brian L. Murphy, Pearlie K. Burnette, Elsa R. Flores, Kenneth Y. Tsai. Immune modulatory effect of pramlintide for cutaneous squamous cell carcinoma treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1227.

Abstract LB-249: HDAC11 regulates lysine acetylation of enolase 1

Therapeutic molecules targeting the activity of histone deacetylases (HDACs) are currently under investigation for the treatment of several malignancies. There are currently eighteen human HDACs and while histone deacetylation is associated with transcriptional repression, acetylated lysine targets are functionally diverse and include cytoplasmic, nuclear, and mitochondrial proteins. Here, we used a new class of novel small molecule inhibitors that are highly selective for HDAC11 to identify its role in the regulation of non-histone proteins. Stable isotope labeling with amino acids in cell culture (SILAC) followed by mass spectrometry in the presence of HDAC11 selective inhibitors identified proteins with acetylation and/or expression changes after treatment and were compared to known HDAC substrates to establish a unique set of putative HDAC11 target proteins. Metabolic processes were highly enriched in this data set. Specifically, acetylated enolase 1 (ENO1, 2-phospho-D-glycerate hydrolase) which catalyzes the conversion of 2-phosphoglycerate to phosphoenolpyruvate (PEP) in the glycolytic pathway was highly altered after HDAC11 inhibition. Using acetylated lysine specific immunoprecipitation, we validated the hyperacetylated state of ENO1 upon HDAC11 inhibition. Functional assays confirmed that the HDAC11 inhibition lowered ENO1-mediated PEP production, and reduced proliferation and viability of hematopoietic and solid tumor cells. Similar observations were obtained in HDAC11 knock down cell lines confirming that HDAC11 is a required molecule in the regulation of ENO1-mediated metabolic regulation. The proteomics data also mapped three distinct target lysine residues of HDAC11 in ENO1 and each of these residues were substituted to either an acetylated or an un-acetylated lysine mimic to test their function in ENO1 activity and stability. We confirmed that K335 is the major target site of HDAC11 and its substitution to the acetylated mimic (glutamine) causes loss of enolase activity. Concomitantly, using proton nuclear magnetic resonance spectroscopy we identified some glycolytic intermediates upstream of ENO1 to be increased and downstream intermediates quantitatively reduced after HDAC11 inhibition suggesting that glycolysis is functionally suppressed. Glycolytic pathway disruption was associated with a compensatory increase in oxygen consumption and ATP production through oxidative phosphorylation in these oncogene transformed tumor cells, but not in their non-transformed counterparts. Suppression of fatty acid oxidation by inhibiting carnitine palmitoyltransferase 1 (CPT-1) or blocking glutamine utilization by inhibiting glutaminase (GLS1) in combination with HDAC11 inhibition resulted in a cooperative reduction in cellular ATP levels further supporting a direct role of HDAC11 in regulating glycolysis in tumor cells. For the first time, this study mechanistically and functionally defines a cytoplasmic non-histone protein regulated by HDAC11.

Citation Format: Vasundhara Sharma, Agni Christodoulidou, Lanzhu Yue, Aileen Y. Alontaga, William E. Goodheart, Rebecca Hesterberg, Xiaozhang Zheng, Matthew W. Martin, Jennifer Y. Lee, Pearlie K. Burnette, Kenneth L. Wright. HDAC11 regulates lysine acetylation of enolase 1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-249.

Abstract 4960: Recent ultraviolet radiation exposure and circulating immunosuppressive T-regulatory cells

Background: Ultraviolet radiation exposure (UVR) is a risk factor for several different cancer types. While the mutagenicity of UVR is well-documented, UVR’s effects on human systemic immune function are not well understood. Several lines of evidence suggest that UVR may have immunosuppressive effects, however, no epidemiologic studies have investigated the association between quantitative measures of UVR and a biomarker of immune function. Objective: To evaluate the association between UVR and systemic immune function, we conducted a cross-sectional analysis of recent UVR and circulating regulatory T- cells (“Tregs”) among a cohort of skin cancer screening patients. Methods: 350 patients undergoing regular skin cancer screenings with no prevalent skin cancer at the time of enrollment were recruited from the University of South Florida Dermatology clinic. At the baseline visit, blood was obtained, and a spectrophotometer was used to measure skin pigmentation at a sun-unexposed site (the axilla) and two sun-exposed sites: the forehead and the upper forearm. Recent sun exposure was quantified as the difference in readings between the sun-exposed and sun-unexposed sites. Using flow cytometry assays, lymphocyte samples were examined for Tregs (CD4+CD25+ CD127lowFoxp3+), and proportions of Tregs with enhanced immunosuppressive function (CD27-, CD45RA- Treg) and skin tissue affinity (CLA+, CCR4high) were determined. Associations between UVR exposure and Tregs were described using Spearman correlation coefficients. Linear regression using log-transformed values of UVR and Tregs was used to adjust for age and sex. Results: Among all 350 participants, UVR was positively correlated with circulating immunosuppressive CD27-, CD45RA- Tregs (r=0.127, p=0.020 for UVR measured at the forehead and r=0.197, p=0.0002 for UVR measured at the forearm). UVR measured at the forearm was also positively correlated with skin-homing Tregs expressing CLA (r=0.167, p=0.002) and CCR4 (r=0.19, p=0.0004). When participants were categorized into light versus dark constitutive pigmentation based on the median value of spectrophotometer readings for the sun-unexposed axilla, the correlation between UVR averaged across the forehead and forearm was more strongly correlated with immunosuppressive Tregs among lighter-skin participants (r=0.30, p<0.001) than darker-skin participants (r=0.065, p=0.400). Conclusion: Recent UVR is positively associated with increased levels of circulating immunosuppressive Tregs, including Tregs with skin tissue affinity, with the association being stronger among naturally lighter-skinned individuals. UVR-associated immunosuppressive effects among otherwise immunocompetent individuals may play a role in skin cancer carcinogenesis.

Citation Format: Dana E. Rollison, Shalaka S. Hampras, Jane L. Messina, Neil A. Fenske, Basil S. Cherpelis, Michael J. Schell, Rhianna Reed, Juliana Balliu, Rebecca Hesterberg, Afua A. Akuffo, Pearlie K. Burnette. Recent ultraviolet radiation exposure and circulating immunosuppressive T-regulatory cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4960. doi:10.1158/1538-7445.AM2017-4960

Abstract 3439: Interaction between cutaneous human papillomavirus infection and telomere length in association with cutaneous squamous cell carcinoma

Background: We previously reported that cutaneous human papillomavirus (HPV) infection was associated with significantly increased risk of cutaneous squamous cell carcinoma (SCC), while longer telomeres were associated with significantly reduced risk of SCC. We conducted further research to evaluate the interaction between cutaneous HPV and telomere length in association with SCC. Methods: Previously, a clinic based case-control (173 SCC cases and 300 controls) study was conducted, between 2007-2008, at the University of South Florida and Moffitt Cancer Center. HPV seropositivity (33 types) and DNA positivity (25 beta-HPV types) in eyebrow hairs (EB) and SCC tumors were measured using multiplex assays. Using quantitative PCR, relative telomere length was measured in peripheral blood leukocytes by determining the ratio of telomere repeat copy number to a single-copy gene copy number for each sample. For the present analyses, subjects with available data on telomere length and a) HPV serology (135 cases and 201 controls), b) HPV DNA in EB (130 SCC cases and 195 controls) and c) HPV DNA in SCC tumors (117 cases), were included. Association between telomere length and SCC was examined after stratification by HPV serostatus and HPV DNA status in EB, and odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression, adjusting for age and gender. Results: Telomere length did not differ significantly between beta-HPV seronegative (mean = 1.16, standard deviation (SD) = 0.57) and seropositive controls [mean (SD) = 1.24(0.75), P value = 0.56], or by tumor HPV DNA status (P value = 0.93). Longer telomere length was associated with significantly reduced risk of SCC among subjects seronegative to all HPV types or seropositive to a single beta1 HPV type (OR = 0.01, 95% CI = 0.001-0.10), while no association was observed among those seropositive to >1 beta1 HPV types (OR = 1.01, 95% CI = 0.95-1.07, Pinteraction = <0.0001). A significant interaction (Pinteraction = 0.0004) was also observed between telomere length and DNA positivity for > = 1 beta-HPV types in EB in association with SCC (OREB DNA negative = 0.003, 95% CI = <0.001-0.09; OREB DNA positive = 1.02, 95% CI = 0.98-1.06). Further, longer telomere length was associated with 62% (OR = 0.38, 95% CI = 0.19-0.75, Pinteraction = 0.004) and 55% (OR = 0.45, 95% CI = 0.23-0.90, Pinteraction = 0.01) reduced risk of SCC among subjects DNA negative for all beta-HPV types or positive for a single beta1 or beta2 type, respectively, while no associations were observed among those with EB DNA positivity for >1 beta1 or beta2 types (OR = 1.02, 95% CI = 0.98-1.07 for both groups). In summary, multiple beta-HPV infections showed significant statistical interaction with telomere length in association with SCC. Conclusion: Presence of cutaneous HPV infection may attenuate the protective effect of longer telomeres on the risk of SCC.

Citation Format: Shalaka S. Hampras, Michael Pawlita, Massimo Tommasino, Jong Park, Pearlie K. Burnette, Neil A. Fenske, Basil A. Cherpelis, Dana E. Rollison. Interaction between cutaneous human papillomavirus infection and telomere length in association with cutaneous squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3439.

Abstract A86: Harnessing T-cell homeostasis to diagnose and treat solid and liquid tumors

T-cell populations are subject to homeostatic control from cytokines and microenvironmental signaling. Disruption of homeostasis can cause changes to the dynamics of the system that have implications for the progression of cancer. Here we present two mathematical models that examine the progression of tumors in the context of T-cell homeostasis and provide therapeutic decision support in the clinic. Model 1: During a chronic disease such as cancer, T cells often become tolerant to the antigens presented by the disease. This tolerant state effectively limits the response of the immune system to the tumor. Experimental evidence has shown that depletion of T-cells can lead to a loss of T-cell tolerance. During the homeostatic phase of T-cell compartment repopulation, there is a temporary window of opportunity during which T cells lose their tolerant state, allowing them to respond to tumor antigens. In addition, clonal expansion of the tumor-specific T-cell clone may be enhanced during the regrowth phase due to increased stimulation. We use an ordinary differential equation (ODE) model to explore the effect of T-cell depletion and homeostatic repopulation on the loss of tolerance in the T-cell compartment and subsequent effectiveness of immune-mediated tumor cytotoxicity. The model predicts different outcomes for the tumor and T-cell compartment, dependent on the strength and schedule of the depletion therapy. The optimal regimen can lead to tumor control in some cases, but T-cell exhaustion is also common dynamic predicted by the model. By understanding the effects of T-cell depletion, immune depleting therapies can be optimized to enhance immune potential. Model 2: Large Granular Lymphocytic Leukemia (LGLL) is a T-cell lymphoproliferative disorder that exhibits clonal expansion of a subset of T cells. Since there are no clinical biomarkers to predict the aggressiveness of the disease, treatment decisions are often made on a watch and wait approach. Using a set of ODEs, we develop a model of LGLL that uses clinical patient data from diagnosis to predict the timeframe for progression of the disease. Our experimental results have suggested that the disease is caused by a change in sensitivity to both positive and negative regulators of T-cell homeostasis. The model incorporates these cell-specific mechanisms to investigate their effect when placed in a homeostatic setting. The level of dysregulation as measured from patient-specific data determines the rate of outgrowth of the diseased T-cell clone, and therefore serve as a useful predictive tool for managing treatment decisions in the clinic.

Citation Format: Mark Robertson-Tessi, Derek Park, Kimberly Luddy, Adam Mailloux, Pearlie K. Burnette, Alexander Anderson. Harnessing T-cell homeostasis to diagnose and treat solid and liquid tumors. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr A86.

Functional association of TGF-beta receptor II with cyclin B

Utilizing the cytoplasmic tail of Transforming Growth Factor Receptor Type II (TGFbeta RII) as bait in a yeast two hybrid system, we have identified human cyclin B2 as a direct physical partner of TGFbeta RII. Analysis of deletion mutants of glutathione-S-transferase (GST)-cyclin B2 mapped its binding domain for TGFbeta RII to the C-terminal and revealed a negative regulatory region immediately upstream of the cyclin box. Using recombinant proteins, Cdc2 was demonstrated to indirectly interact with TGFbeta RII via cyclin B2. This interaction was reproduced in THP-1 monocytic cells, where TGFbeta treatment markedly enhanced the ability of cyclin B2 and, correspondingly, Cdc2 from TGFbeta-treated THP-1 cells, to bind the GST-TGFbeta RII fusion protein. More importantly, TGFbeta RII co-precipitated with cyclin B2 in TGFbeta-treated THP-1 cells. TGFbeta treatment also caused threonine phosphorylation of Cdc2 in the TGFbeta RII-cyclin B2-Cdc2 complex in THP1 cells, in parallel with down regulation of Cdc2 function as measured by histone H1 kinase activity. Cyclin B1 had the same capacity to bind TGFbeta RII and mediate indirect Cdc2 binding. These results suggest an alternative mechanism that cell cycle arrest in the G1/S phase caused by TGFbeta may, in part, be due to inactivation of cyclin B/Cdc2 kinase, which is needed for entry into the G2/M phase.

Rifampin-associated thrombocytopenia secondary to poor compliance

Rifampin can be associated with severe adverse effects such as hepatitis, acute renal failure, hemolytic anemia, and thrombocytopenia. Thrombocytopenia has traditionally been associated with intermittent therapy. This article reports the occurrence of rifampin-associated thrombocytopenia in an indigent patient after a four-month lapse in therapy for pulmonary tuberculosis. The patient's platelet count dropped rapidly to a level of 1000/mm3 after receiving a single 600 mg dose of rifampin. After returning to a normal level of greater than 100,000/mm3, the patient's platelets again dropped to 1200/mm3 with readministration of rifampin. The long-term therapy necessary to eradicate the Mycobacterium tuberculosis organism makes economic considerations important. This patient and other indigent patients who may be poor compliers because they are unable to buy the necessary medication may be at a higher risk for adverse reactions.