Taste evolution in an herbivorous drosophilid

Plant secondary metabolites pose a challenge for generalist herbivorous insects because they are not only potentially toxic, they also may trigger aversion. On the contrary, some highly specialized herbivorous insects evolved to use these same compounds as 'token stimuli' for unambiguous determination of their host plants. Two questions that emerge from these observations are how recently derived herbivores evolve to overcome this aversion to plant secondary metabolites and the extent to which they evolve increased attraction to these same compounds. In this study, we addressed these questions by focusing on the evolution of bitter taste preferences in the herbivorous drosophilid Scaptomyza flava, which is phylogenetically nested deep in the paraphyletic Drosophila. We measured behavioral and neural responses of S. flava and a set of non-herbivorous species representing a phylogenetic gradient (S. pallida, S. hsui, and D. melanogaster) towards host- and non-host derived bitter plant compounds. We observed that S. flava evolved a shift in bitter detection, rather than a narrow shift towards glucosinolates, the precursors of mustard-specific defense compounds. In a dye-based consumption assay, S. flava exhibited shifts in aversion toward the non-mustard bitter, plant-produced alkaloids caffeine and lobeline, and reduced aversion towards glucosinolates, whereas the non-herbivorous species each showed strong aversion to all bitter compounds tested. We then examined whether these changes in bitter preferences of S. flava could be explained by changes in sensitivity in the peripheral nervous system and compared electrophysiological responses from the labellar sensilla of S. flava, S. pallida, and D. melanogaster. Using scanning electron microscopy, we also created a map of labellar sensilla in S. flava and S. pallida. We assigned each sensillum to a functional sensilla class based on their morphology and initial response profiles to bitter and sweet compounds. Despite a high degree of conservation in the morphology and spatial placement of sensilla between S. flava and S. pallida, electrophysiological studies revealed that S. flava had reduced sensitivity to glucosinolates to varying degrees. We found this reduction only in I type sensilla. Finally, we speculate on the potential role that evolutionary genetic changes in gustatory receptors between S. pallida and S. flava may play in driving these patterns. Specifically, we hypothesize that the evolution of bitter receptors expressed in I type sensilla may have driven the reduced sensitivity observed in S. flava, and ultimately, its reduced bitter aversion. The S. flava system showcases the importance of reduced aversion to bitter defense compounds in relatively young herbivorous lineages, and how this may be achieved at the molecular and physiological level.

Abstract 722: The hallmark of COVID-19 cancer disparities: Cellular sequelae

Coronavirus disease-19 (COVID-19). Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a novel coronavirus resulting in a severe threat to safety and public health. Genetic analyses suggest that SARS-COV-2 belongs to the Betacoronavirus group and Middle East respiratory syndrome coronavirus (MERS-CoV). Like most viruses, some are oncogenic, and genetic instability is involved in the initiating factor for tumor progression that is known to lead to malignancy, resulting in disease sequelae. Genomic instability is characterized by the increased rate of acquisition of alterations in the mammalian genome. These changes encompass a diverse set of biological end points including gene mutation and amplification, cellular transformation, clonal heterogeneity and delayed reproductive cell death. The loss of stability of the genome is becoming accepted as one of the most important aspects of viral induced carcinogenesis, and the numerous genetic changes associated with cancer cell implicate genomic stability as contributing to the neoplastic phenotype. The aim of this study is to analyze the influence of COVID-19 cancer related diseases and determine the epigenetic-genomic profiles in these diseases. In our experimental procedures, we will use oral epithelium cells as a model for this cancer study. We proposed a novel approach to study COVID-19-induced genetic changes with oral epithelium cells. We used these cells with COVID-19 co treatment to determine mechanisms that lead cells into crisis. Preliminary data using oral viral infected cells show that the viral infection can trigger certain gatekeeper proteins like p53 and pRB to be degraded and forcing cells to go into crises, and telomerase is turned on. In this study we will determine if COVID-19 transfected cells can follow the process using the Hayflick model, which show cells that are in crises, and some may progress to cancer. In summary, preliminary data show that viral infected cells that are none cancerous and are telomerase positive, may use a similar mechanism to send cells into crisis that turn telomerase on resulting in cellular malignancy.

Citation Format: Eva McGhee, Mengtao LI, Yi-Ling Lin, Nefertari Carr, Chinelo Njubigbo, Rohun Sadeghi, Brooke Su-Velez, Julian Handler, Adin Handler, Judith Okoro, Sebhat Afework, Jay Vadgama. The hallmark of COVID-19 cancer disparities: Cellular sequelae [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 722.

Abstract 427: A mouse model for studying oncogenesis of HPV-associated oropharyngeal cancer

The human papillomavirus (HPV) causes 70% of oropharyngeal cancers in the United States. While the molecular and cellular mechanisms and the stepwise progression of HPV-related cervical cancer have been well studied, oropharyngeal HPV carcinogenesis remains to be unraveled since an equivalent HPV premalignant stage has never been identified in clinical oropharyngeal tissues. In this study, a series of keratinocyte cell lines derived from the base of the tongue of C3H mice were established. These cells formed varying degrees of malignancy in the syngenetic mice and are used to study the biology of HPV-related oropharyngeal cancer in an immunocompetent host. Keratinocytes from the base of the tongue were isolated from C3H newborns and were subsequently retrovirally immortalized with TERT or HPV16 E6E7 oncoproteins, with or without oncogene H-ras. They are designated MOKT1 (TERT), MOKT1/H-ras (TERT/H-ras), MOKE2 (E6E7), or MOKE2/H-ras (E6E7/H-ras). These cells were injected in the masseter muscle of syngeneic mice and the developing lesions were harvested for histological analysis over a time course of 1 month. E6E7 transformed MOKE2 cells exhibited features of HPV associated cancer cells. We found that p63 and phosphorylated STAT3 were upregulated in MOKE2 cells in comparison to MOKT1 cells. MOKE2 cells obtained growth advantages with increased cell proliferation and decreased apoptosis. In addition, MOKE2 cells showed increased cell migration activity in wound healing assays. While all cell lines grew indefinitely in vitro, MOKT1 and MOKT1/H-ras failed to show any sign of malignancy when implanted in vivo. MOKE2 demonstrated features of malignancy, but the phenotype was transient. Host immunity does not appear to be the determining factor for suppressing tumor growth as MOKE2 regressing also occurred when implanted in immunodeficient NSG mice. Only MOKE2/H-ras cells were capable of progressing and establishing permanent cancer. Ourdata suggest that differentiation induced cell growth arrest may contribute to tumor regression and a second hit is required to overcome such arrest. The MOKE2 cells can be used in syngeneic mice to study secondary oncogenic factors in the development of HPV-related oropharyngeal cancer.

Citation Format: Eva McGhee, Yi-Ling Lin, Jay Vadgama, Khadijah Lang, Judith Okoro, Victoria Vidal, Naomi Long, Mengtao Li. A mouse model for studying oncogenesis of HPV-associated oropharyngeal 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 427.

Abstract 3789: Genomic instability changes acquired by HPV16 E6/E7 targeting multipolar mitoses aneuploidy: Cellular sequelae

Malignant progression of high-risk Papillomavirus (HPV), associated lesions is a slow and inefficient process. HPV a non-enveloped epitheliotropic double stranded DNA virus, is an etiological agent of oral cancer. Oral cancer is related to the persistent infection by high-risk HPV type 16, E6/E7 oncoproteins. The E6/E7 complex significantly contribute to the carcinogenic genetic instability effect of high-risk HPV through the degradation of two gatekeeper proteins, p53 and pRB, respectively. This process is associated with viral genome integration into a host cellular chromosome and accumulation of numerical and structural chromosome aberrations. Viral genome integration results in consistent, sustained and dysregulated expression of the E6 and E7 oncogenes, and continued E6/E7 expression is necessary for maintenance of the transformed phenotype of HPV positive cancer cell. Induction of genomic instability by high-risk HPV E6/E7 demonstrates that HPV also drive malignant progression through targeting the nuclear and mitotic apparatus protein-1 (NuMA), and through subversion of DNA double strand break repair by HPV E6/E7 induced centrosome abnormalities. This in turn may cause abnormal localization of the microtubule protein dynein. The NuMA provides a cohesive force that guarantees the integrity of the mitotic spindle poles. However, there are no studies addressing the relationship between HPV16 infection-oral cancer, NuMA expression, and genomic instability. The aim of this study determined if HPV16 E6/E7 subverts centrosome coalescence in oral cancer caused by HPV oncogenes targeting the NuMA protein. In our experimental procedures, we proposed a novel approach to study HPV-induced chromosomal changes with reconstructed human oral epithelium in SCID mouse. We used HPV16, which is the most common HPV type found in oral cancer. Two plasmids were used to produce HPV-16 E6/E7. The first plasmid p16sheLL expresses the two viral capsid proteins, L1 and L2. The second plasmid pBR322HPV16 contains the full length HPV-16 genome. This approach closely mimics the architecture of normal human oral epithelium. In our study, we first focused on analyzing selected cellular processes involving multipolar mitoses. We examined Dynein localization in mitotic cells by immunofluorescence. We also analyzed progressive morphological and cytopathic changes in HPV-infected oral epithelia by using molecular cytogenetic analysis. In summary these data indicate that NuMA expression is alternated, and HPV16 E6/E7 oncoproteins can promote increased upregulation of genomic instability by induction of centrosome abnormalities and inhibition of DNA double strand break repair. We also found High-risk HPV16 E6/E7 oncoproteins induced mitotic defects and genetic aneuploidies through induction of supernumerary anaphase bridges, supernumerary centrosomes, and DNA double strand breaks.

Citation Format: Eva McGhee, Mengtao Li, Yi-Ling Lin, Khadijah Lang, Meidrah Tyler, Judith Okoro, Mai Do, Naomi Long, Jenna Cormier, Adin Handler, Julian Handler, Sameeran Das, Benjamin Liu, Anthonia Duru, Billy Ballard, Roland Pattillo, Jay Vadgama. Genomic instability changes acquired by HPV16 E6/E7 targeting multipolar mitoses aneuploidy: Cellular sequelae [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 3789.

Abstract 3388: Molecular characterization of HPV type 18 cervical cancer: Upregulation of telomerase expression and induced chromosomal instability by E6 and E7 oncoproteins

Human papillomavirus (HPV), high-risk type 18, is directly associated with approximately 98% incidence of invasive cervical cancer. Epithelial cells infected with HPV-18 become transformed and exhibit overexpression of telomerase activity and chromosomal instability. As a result of this transformation, E6 and E7 oncoproteins are perpetually expressed: E6 degrades the tumor suppressor p53; E7 inhibits the tumor suppressor pRB, leading to uncontrollable growth and the extension of telomere length. While a few studies explored the chromosomal instability induced by HPV E6 and E7 oncoproteins, the full scope of the problem has not been clearly characterized. In this research we investigated HPV-18 acquired genomic instability by E6 and E7 oncoproteins. HPV-positive cervical cancer cells, HeLa, were studied through spectral karyotyping (SKY), Giemsa banding (G-banding), telomere length, and telomerase activity using PCR ELISA assay and the TRAPeze XL Kit, which uses fluorescence energy transfer. With the use of SKY, G-banding, and chromosomal instability analysis, HeLa cells exhibited many aneuploidies. In our results, there were consistent translocations on chromosomes 4 and 11, with deletions on chromosomes 11 and 20. There were also other translocations on chromosomes 9 and 20, with deletions on chromosome 10. Additionally, copies of chromosome 5 and unidentifiable marker chromosomes were noted. Moreover, telomerase data suggest that upregulated expression of telomerase activity correlates with the increase in chromosomal instability. The aforementioned aneuploidy is demonstrative of the induced chromosomal instability from HPV-18 infection. In addition to the tumor-suppressor disruption acquired by E6 and E7 oncoproteins, HeLa cells showed gene deletion on chromosome 11. The ATM gene, which is specifically located between distal regions 11q22.3 and 11q23 of chromosome 11, is known to help identify breaks in DNA and plays a crucial role in DNA repair. Damage to the ATM gene may further play an important role in increasing cancer progression.

Citation Format: Mai Do, Nichelle Cox, Naomi Long, Liliana Zarate, Chinelo Ezechukwu, Jenna Cormier, Hyun Chung, Meidrah Tyler, Judith Okoro, Diondra Harris, Victoria Vidal, Jerica Watson, Ellie Canty, Shyam Arya, Benjamin Liu, Roland Pattillo, Billy Ballard, Jay Vadgama, Eva McGhee. Molecular characterization of HPV type 18 cervical cancer: Upregulation of telomerase expression and induced chromosomal instability by E6 and E7 oncoproteins [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 3388.

Elimination of Cancer Health Disparities through the Acceleration of HPV Vaccines and Vaccinations: A Simplified Version of the President's Cancer Panel Report on HPV Vaccinations

The human papillomavirus (HPV) is a major public health concern affecting both females and males. HPV is associated with cervical, anal, head and neck cancers. About 99% of all cervical cancers are related to HPV. HPV vaccines, Gardasil, Cervarix, and Gardasil 9 are used in the primary prevention of HPV related cancers. Gardasil and Gardasil 9 are available for use in both females and males ages 9 to 26, while Cervarix is available for females ages 9 to 25. Gardasil 9 was approved by the FDA for prevention against additional HPV types. Despite the availability of this preventative measure against cervical cancer, the rate of HPV vaccination in the United States remains lower than that of other industrialized nations. The purpose of this study is to elucidate mechanisms to help increase the HPV vaccination rate by using education as a tool; by simplifying the president report so that lay person can understand the information presented in the report. Through the quantitative examination of the data from the states with the lowest and highest vaccination rates, using SPSS statistical analysis; we analyzed several factors involved with the low uptake of the vaccines. The results collected show that socioeconomic status, misconceptions about HPV, and misconceptions about the safety of the vaccines were identified as possible obstacles to the effective uptake of HPV vaccinations. The proposals made by the President’s Cancer Panel to accelerate the uptake of vaccines include, increasing coverage of the vaccines through government-sponsored programs, and the Affordable Care Act; increasing accessibility to vaccines through pharmacies, schools, and clinics; and disseminating more information on HPV to healthcare providers, parents, caregivers, and patients. Allowing greater accessibility to the vaccines for all populations regardless of income, education, and eliminating misconceptions of the vaccines would play a significant role in eliminating cancer.