Rapid evolution of glycan recognition receptors reveals an axis of host-microbe arms races beyond canonical protein-protein interfaces

Detection of microbial pathogens is a primary function of many mammalian immune proteins. This is accomplished through the recognition of diverse microbial-produced macromolecules including proteins, nucleic acids and carbohydrates. Pathogens subvert host defenses by rapidly changing these structures to avoid detection, placing strong selective pressures on host immune proteins that repeatedly adapt to remain effective. Signatures of rapid evolution have been identified in numerous immunity proteins involved in the detection of pathogenic protein substrates, but whether similar signals can be observed in host proteins engaged in interactions with other types of pathogen-derived molecules has received less attention. This focus on protein-protein interfaces has largely obscured the study of fungi as contributors to host-pathogen conflicts, despite their importance as a formidable class of vertebrate pathogens. Here, we provide evidence that mammalian immune receptors involved in the detection of microbial glycans have been subject to recurrent positive selection. We find that rapidly evolving sites in these genes cluster in key functional domains involved in carbohydrate recognition. Further, we identify convergent patterns of substitution and evidence for balancing selection in one particular gene, MelLec, which plays a critical role in controlling invasive fungal disease. Our results also highlight the power of evolutionary analyses to reveal uncharacterized interfaces of host-pathogen conflict by identifying genes, like CLEC12A, with strong signals of positive selection across mammalian lineages. These results suggest that the realm of interfaces shaped by host-microbe conflicts extends beyond the world of host-viral protein-protein interactions and into the world of microbial glycans and fungi.

Abstract 1525: Upregulation of genes linked to epithelial-mesenchymal transition in anaplastic thyroid cancer

Introduction: Epithelial-mesenchymal transition (EMT) plays a major role in invasion, migration, and drug resistance in cancer. There are several signaling pathways associated with EMT, including PI3K/Akt and NFΚB. EMT is present in several cancer types, especially in the recurrent and metastatic setting. Anaplastic thyroid cancer (ATC) accounts for 2% of thyroid cancers and are notoriously aggressive. Clinically, these patients have poor survival rates and are resistant to standard of care therapies. ATC can arise de novo from follicular thyroid cells or in association with papillary thyroid carcinoma (PTC). Therefore, we investigated the differences in gene signature and cancer pathway expression in these histological subtypes, and their potential association with genes upregulated in EMT.

Methods: De novo ATC and mixed ATC/PTC cases (N=12) from 1998 to 2018 with viable formalin-fixed paraffin-embedded (FFPE) tissue were identified and selected. 8 cases exhibited both PTC and ATC components while the rest (N=4) were pure ATC cases, as confirmed by a pathologist. In the 4 mixed ATC/PTC histology group specimen, 3 were identified by a pathologist to contain greater than 80% ATC involvement while the fourth was characterized as 40% ATC and 60% PTC. The NanoString PanCancer Pathway panel, which contains 770 genes from 13 signaling pathways, was performed with the extracted tumor RNA to evaluate and compare the gene signatures of the pure ATC versus mixed ATC/PTC cases.

Results: Majority of patients (N=11, 92%) developed metastatic disease, a common feature of ATC, and are currently deceased (N=10, 83%). Using Nanostring panel on the patient specimen, we identified differential expression of genes and cancer pathways in the mixed ATC/PTC cohort in comparison to the pure ATC cohort. 28 genes, strongly associated with cancer pathways including MAPK, cell cycle-apoptosis, driver genes, and RAS, were significantly upregulated with at least two-fold change in the mixed ATC/PTC histology group in comparison to the pure ATC histology group (p<0.01). Three genes strongly linked with EMT demonstrated increased expression. MMP3 was the most upregulated gene in the mixed ATC/PTC histology group, with a 41.4 linear fold change (p=0.001), and has been shown to induce EMT in various cancers. Two other EMT-related genes, TNF and PIK3CG, were similarly significantly expressed in the mixed ATC/PTC versus the pure ATC histology group (p<0.005).

Conclusion: Our results demonstrate a significant difference in the expression of cancer-related genes between the mixed ATC/PTC and the pure ATC histology groups. Our findings also suggest a correlation between mixed ATC/PTC histology cases and genes associated with EMT.

Citation Format: Rebecca R. Pharaon, Hannah J. Young, Kimberley-Jane C. Bonjoc, Feras Ally, Holly Yin, Robert Kang, Thomas Gernon, Ammar Chaudhry, Ellie Maghami. Upregulation of genes linked to epithelial-mesenchymal transition in anaplastic thyroid cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1525.

Role of AXL in metastatic melanoma and impact of TP-0903 as a novel therapeutic option for melanoma brain metastasis

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Background: Melanoma brain metastases (MBM) are common with a median overall survival of 4-5 months. Although immunotherapies have improved clinical outcomes and have doubled overall survival in MBM, there is a high incidence rate of relapse caused by drug resistance. AXL, a receptor tyrosine kinase (RTK), is associated with drug resistance and metastasis in many cancers. The activation of AXL via trans-phosphorylation regulates multiple signaling pathways that induce tumor survival, metastasis, drug resistance, and epithelial-to-mesenchymal transition (EMT). In MBM, AXL is upregulated and associated with disease progression, promoting cell invasion and migration. This suggests that targeting AXL can be a novel strategy to overcome treatment-related resistance in MBM. TP-0903, an investigational small molecule inhibitor of AXL, has shown efficacy in reversing the mesenchymal phenotype and re-sensitizing resistant cancer cells to targeted therapies in heme malignancies, pancreatic, and breast cancer. We aim to investigate the efficacy of TP-0903 in MBM. Methods: The Cancer Genome Atlas (TCGA) data was utilized to investigate the signaling pathways downstream of AXL that are upregulated in advanced melanoma. Nine signaling molecules including AKT1, mTOR, and PAK4 were analyzed to identify any correlation between gene expression levels and overall survival. Four metastatic melanoma cell lines were used to evaluate the effect of TP-0903 on cell viability and active AXL downregulation was assessed in vitro through MTS cell viability assays and Immunoblotting. Wound closure assays were executed to understand the functional consequences of AXL downregulation. Results: In all nine genes, high expression levels confer poor survival probability. Cell viability assays of four malignant melanoma cell lines showed that TP-0903 treatment resulted in IC50 values ranging from 32 – 692 nM. Western blot analysis indicated that TP-0903 reduced the levels of phosphorylated AXL in malignant melanoma cell lines. In addition, increasing TP-0903 concentrations reduced the rate of cell migration in these malignant melanoma cell lines. Conclusions: AXL plays a role in EMT, treatment resistance, and metastasis in MBM, resulting in poor survival. Our findings suggest TP-0903 is effective in reducing cell migration, inhibit metastasis, and can be a potential therapeutic option in MBM.

Differential immune pathways in classic and mixed variants of anaplastic thyroid cancer

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Background: Patients with anaplastic thyroid cancer (ATC) have poor outcomes due to treatment resistance with an estimated 5-year survival rate of 7%. Although “classic” ATC can arise de novo from follicular thyroid cells, it can also arise in association with papillary thyroid carcinoma (PTC), as a “mixed” histology. The immunologic and molecular differences between these histological subtypes have not been well-characterized. We aimed to investigate the differences in immune signatures in these histological subtypes to assess immune pathway differences in the classic ATC and mixed ATC/PTC tumor microenvironment. Methods: Classic ATC and mixed ATC/PTC cases (N = 12) from 1998 to 2018 with viable formalin-fixed paraffin-embedded (FFPE) tissue were identified and selected by a board-certified pathologist. 4 samples exhibited both PTC and ATC components while 8 were classic ATC cases, as confirmed by a pathologist. In the 4 mixed ATC/PTC histology specimens, 3 were identified to contain greater than 80% ATC involvement while the fourth was characterized as 40% ATC and 60% PTC. The NanoString Immune Profiling panel contains more than 770 genes. It was performed with extracted RNA to evaluate and compare the gene expression of classic ATC versus mixed ATC/PTC. Results: Majority of patients (N = 11) developed metastatic disease, a common feature of ATC, and are currently deceased (N = 10). The NanoString panel identified several differentially expressed immune pathways in the mixed ATC/PTC in comparison to the classic ATC group. There is upregulation of CD3 (p < 0.01) and CD8 (p < 0.01) transcripts in the mixed ATC/PTC group, but not CD4 transcripts (p > 0.05). Additionally, we found that genes associated with B cell and T cell function were significantly upregulated in the mixed ATC group, including CD27 (p < 0.01), CD28 (p < 0.05), BTLA (p < 0.01), CTLA4 (p < 0.01), LAG3 (p < 0.05), and TIGIT(p < 0.01). We did not observe any significant differences in the expression of PD1 (p > 0.05) or MR1 (p > 0.05) between classic ATC and mixed ATC variants. Conclusions: Our study demonstrates a significant difference in the immune landscape between classic and mixed variants of ATC. Our results indicate there may be an increase in immune cell infiltration and tumor inflammation in the mixed ATC variant, which suggests patients with the mixed ATC variant may show a positive response to immunotherapy.

Epidemiology of cardiovascular risk factors in chronic renal disease

Treatment and prevention of cardiovascular disease in the general population has benefited greatly from the identification of cardiovascular disease risk factors. Given the particularly high risk of cardiovascular disease and total mortality among patients with chronic renal insufficiency (CRI) and end-stage renal disease (ESRD), it is important to assess the role of traditional and nontraditional risk factors for cardiovascular disease. This review discusses the foundations of risk factor epidemiology and briefly summarizes the evidence regarding cardiovascular risk factors in renal disease. Diabetes and hypertension have a very high prevalence in patients with CRI. Patients with CRI and ESRD also have a higher frequency of cardiac dysfunction and left ventricular hypertrophy, which further increase the risk of cardiovascular disease. Finally, patients with renal disease have a higher prevalence of less established risk factors, including low HDL, and high triglycerides, lipoprotein(a), and homocysteine, where prospective studies and clinical trials are needed to provide a scientific basis for reduction of cardiovascular risk among patients with renal disease.

Nigrostriatal dopamine system mediates baroreflex sensitivity in rats

Both sham-operated rats and rats with lesions of the nigrostriatal dopamine (DA) pathway were subjected to increasing or decreasing carotid sinus pressure (respectively produced by phenylephrine injection or bilateral carotid occlusion) and their striatal DA release and baroreflex responses were compared. In sham-operated rats, phenylephrine produced both increased striatal DA release and decreased heart rate, while bilateral carotid occlusion produced the opposite effects. Both the striatal DA release and baroreflex responses produced by phenylephrine or carotid occlusion were attenuated by lesions of the nigrostriatal DA pathway induced by intramedial forebrain bundle injection of 6-hydroxydopamine. The data indicate that the nigrostriatal DA pathway mediates baroreflex sensitivity in rats.

Influence of Environmental Quality on Pollen Competitive Ability in Wild Radish

Pollen of Raphanus raphanistrum produced under low nutrient conditions sired fewer seeds than pollen produced under better conditions when the two types were applied on a stigma together. No difference was seen in single-donor crosses. Male mating success can be strongly influenced by the environmental conditions of pollen-bearing plants, a factor overlooked in studies of plant reproductive biology and in standard quantitative genetic crossing designs, where effects of male parent are equated with heritable genetic variation.