ONCOGENIC KRAS AND TELOMERE BIOLOGY IN CRC PROGRESSION

While colorectal cancer (CRC) patients diagnosed with localized stage disease (as defined by SEER) have a 5-year survival rate of 90%, this rate plunges to 14% for patients diagnosed with metastatic CRC. Consequently, there is an immediate imperative to elucidate the mechanisms that drive the transition to advanced CRC. Human CRCs carrying oncogenic mutations in the KRAS oncogene, henceforth referred to as KRAS*, exhibit a 25% higher propensity for developing liver metastases. Similarly, in our CRC mouse model, engineered with an inducible Kras* transgene and conditional null alleles of Apc and Tp53 (referred to as iKAP), KRAS* has been implicated in driving cancer progression and metastasis. Mechanistically, KRAS*-driven cancer metastasis operates, in part, by activating cancer cell-intrinsic TGFβ signaling and suppressing anti-tumoral immunity through the IRF2-CXCL3 axis, which recruits myeloid-derived suppressor cells. Regrettably, emerging therapies targeting KRAS* have demonstrated limited efficacy in clinical settings. This challenge has spurred our efforts to identify and validate additional mechanisms underpinning KRAS*-driven cancer progression, with the ultimate aim of expanding the array of therapeutic targets for metastatic CRC. By utilizing the iKAP model and employing functional gene set enrichment and histological analyses of KRAS*-expressing CRC metastases, we have uncovered a robust adipogenesis signature and an abundance of lipid-rich fibroblasts and angiogenesis in the tumor microenvironment. Consequently, our co-culture experiments involving mouse embryonic fibroblasts and conditioned media from iKAP primary cell lines have induced their differentiation into a cell population displaying traits of both adipocytes and fibroblasts, aptly referred to as \u27lipid-rich fibroblasts.\u27 In the initial segment of my study, I have elucidated the molecular mechanisms through which KRAS*-expressing cancer cells drive lipo-fibrogenesis and have shed light on the tumor biological role of lipid-rich fibroblasts in facilitating KRAS*-driven CRC progression. As only a minority of cases among both human and mouse KRAS* CRC show progression to metastatic disease, it is clear that genetic events beyond KRAS activation play a pivotal role in driving metastases. Notably, patients, irrespective of KRAS mutations, exhibit a nearly identical lymph node metastatic rate of approximately 40%. In order to explore these pro-metastasis events more effectively, I propose an integration of an inducible telomerase reverse transcriptase (LSL-Tert) into our existing iAP model, which is engineered with conditional null alleles of Apc and Tp53. This introduced modification enables us to replicate telomere-based crisis and genome instability, subsequently followed by telomerase reactivation. In prior studies employing telomerase-inducible mouse models of prostate cancer, the introduction of crisis-telomerase sequences led to the development of cancer-relevant genomic aberrations and an escalation in metastatic potential. While the inclusion of genomic instability within the iAP model may not fully replicate the intricacies of the human context, it does provide a platform for identifying gene alterations and biological transformations associated with the metastatic process. In the second phase of my research, I have introduced human-like telomere dynamics into the iAP model (referred to as iTAP) to investigate the consequences of telomere-based crisis and telomerase reactivation in driving metastasis and unraveling the underlying biological changes. These endeavors hold the potential to expedite the discovery of novel therapeutic targets for advanced CRC disease

Race, Politics, and Justice: A Clash of Interpretations

Today\u27s climate of racial reckoning in the United States raises profound questions about the roots of racial-ethnic inequality. While protesters lament and denounce what they view as a systematically racist society that devalues Black lives, critics of the movement condemn the chaos on the streets and what they view as dangerous misdiagnoses of societal ills. The contrast in interpretations goes beyond race, however, with profound moral and emotional differences across the political divide. This essay reviews two major texts representing contrasting interpretations of racial disparities on the ``left\u27\u27 and ``right\u27\u27 in the United States. Applying the tools of political psychology, the essay examines Ijeoma Oluo\u27s So you want to talk about race, and Jason Riley\u27s Please Stop Helping Us: How Liberals Make it Harder for Blacks to Succeed. It will be seen that the claims, counterclaims, and evidence found in each text reflect as much the political sensibilities of the left and right as they do sober analyses of the relevant evidence regarding racial inequality. The second half of the paper will engage in a discussion concerning moral and evolutionary psychology, examining the different moral foundation found in liberals and conservatives, such as Oluo and Riley, respectively, and how such foundations have developed to become part of our ideological identities and the way in which they impact our thoughts, core beliefs, and group affiliations. The findings have implications for the prospects of overcoming confirmation bias and finding common ground regarding the contentious questions of racial inequality and social justice

Molecular basis of heavy-chain class switching and switch region deletion in an Abelson virus-transformed cell line

We demonstrated that a subclone of an Abelson murine leukemia virus-transformed B-lymphoid cell line switched from mu to gamma 2b expression in vitro, by the classical recombination-deletion mechanism. In this line, the expressed VHDJH region and the C gamma 2b constant region gene were juxtaposed by a recombination event which linked the highly repetitive portions of the S mu and S gama 2b regions and resulted in the loss of the C mu gene from the intervening region. An additional recombination event in this subclone involved an internal deletion in the S mu region of the expressed (switched) allele. One end of this deletion occurred very close to the switch recombination point. Despite the recombination-deletion mechanism of switching, the gamma 2b-producing line retained two copies of the C mu gene and two copies of the sequence just 5' to the S gamma 2b recombination point. The possible significance of the retention of these sequences to the mechanism of class switching is discussed

Knowledge About the Human Papillomavirus Vaccine Among Employees at a Tertiary Cancer Center: Room for Improvement

Introduction: The human papillomavirus (HPV) vaccine is recommended by the U.S. Centers for Disease Control and Prevention for routine vaccination of boys and girls to protect against HPV-related cancers and genital warts. To meet the Healthy People 2020 target for HPV vaccination, health care providers must understand the importance of strongly recommending the HPV vaccine to all eligible adolescents. We sought to determine HPV vaccination patterns among employees at a tertiary cancer center and their children and attitudes regarding HPV vaccination among the employees. Methods: All employees at a tertiary cancer center were invited to participate in a cross-sectional survey administered online during July and August 2015. The survey included questions about HPV vaccination of participants and their children, including reasons why vaccine-eligible employees and children had not been vaccinated. Results: Of those eligible, 13% of male and 33% of female employees and 44% of daughters and 24% of sons of employees had completed the vaccine series. The main reasons for not completing the series or not having one’s son completing the series were not knowing that the vaccine was needed and vaccine not recommended by a health care provider. The main reasons for not having one’s daughter complete the series were the two aforementioned reasons and daughter not yet sexually active. Conclusion: Opportunities exist to educate health care workers about the benefits of the HPV vaccine and to increase the number of providers who recommend HPV vaccination to their patients

An ordinary differential equation model for the multistep transformation to cancer

Cancer is viewed as a multistep process whereby a normal cell is transformed into a cancer cell through the acquisition of mutations. We reduce the complexities of cancer progression to a simple set of underlying rules that govern the transformation of normal cells to malignant cells. In doing so, we derive an ordinary differential equation model that explores how the balance of angiogenesis, cell death rates, genetic instability, and replication rates give rise to different kinetics in the development of cancer. The key predictions of the model are that cancer develops fastest through a particular ordering of mutations and that mutations in genes that maintain genomic integrity would be the most deleterious type of mutations to inherit. In addition, we perform a sensitivity analysis on the parameters included in the model to determine the probable contribution of each. This paper presents a novel approach to viewing the genetic basis of cancer from a systems biology perspective and provides the groundwork for other models that can be directly tied to clinical and molecular data.Comment: 12 pages, submitted to Journal of Theoretical Biolog

FoxO3 transcription factor and Sirt6 deacetylase regulate LDL-cholesterol homeostasis via control of the proprotein convertase subtilisin/kexin type 9 (Pcsk9) gene expression

Elevated LDL-cholesterol is a risk factor for the development of cardiovascular disease. Thus, proper control of LDL-cholesterol homeostasis is critical for organismal health. Genetic analysis has identified PCSK9 (proprotein convertase subtilisin/kexin type 9) as a crucial gene in the regulation of LDL-cholesterol via control of LDL receptor degradation. Although biochemical characteristics and clinical implications of PCSK9 have been extensively investigated, epigenetic regulation of this gene is largely unknown. In this work we have discovered that Sirt6, an NAD+-dependent histone deacetylase, plays a critical role in the regulation of the Pcsk9 gene expression in mice. Hepatic Sirt6 deficiency leads to elevated Pcsk9 gene expression and LDL-cholesterol as well. Mechanistically, we have demonstrated that Sirt6 can be recruited by forkhead transcription factor FoxO3 to the proximal promoter region of the Pcsk9 gene and deacetylates histone H3 at lysines 9 and 56, thereby suppressing the gene expression. Also remarkably, overexpression of Sirt6 in high fat diet-fed mice lowers LDL-cholesterol. Overall, our data suggest that FoxO3 and Sirt6, two longevity genes, can reduce LDL-cholesterol levels through regulation of the Pcsk9 gene

An In Vivo Screen Identifies PYGO2 as a Driver for Metastatic Prostate Cancer

Advanced prostate cancer displays conspicuous chromosomal instability and rampant copy number aberrations, yet the identity of functional drivers resident in many amplicons remain elusive. Here, we implemented a functional genomics approach to identify new oncogenes involved in prostate cancer progression. Through integrated analyses of focal amplicons in large prostate cancer genomic and transcriptomic datasets as well as genes upregulated in metastasis, 276 putative oncogenes were enlisted into an in vivo gain-of-function tumorigenesis screen. Among the top positive hits, we conducted an in-depth functional analysis on Pygopus family PHD finger 2 (PYGO2), located in the amplicon at 1q21.3. PYGO2 overexpression enhances primary tumor growth and local invasion to draining lymph nodes. Conversely, PYGO2 depletion inhibits prostate cancer cell invasion in vitro and progression of primary tumor and metastasis in vivo In clinical samples, PYGO2 upregulation associated with higher Gleason score and metastasis to lymph nodes and bone. Silencing PYGO2 expression in patient-derived xenograft models impairs tumor progression. Finally, PYGO2 is necessary to enhance the transcriptional activation in response to ligand-induced Wnt/β-catenin signaling. Together, our results indicate that PYGO2 functions as a driver oncogene in the 1q21.3 amplicon and may serve as a potential prognostic biomarker and therapeutic target for metastatic prostate cancer.Significance: Amplification/overexpression of PYGO2 may serve as a biomarker for prostate cancer progression and metastasis. Cancer Res; 78(14); 3823-33. ©2018 AACR

Foxo1 Links Hyperglycemia to LDL Oxidation and Endothelial Nitric Oxide Synthase Dysfunction in Vascular Endothelial Cells

OBJECTIVE: Atherosclerotic cardiovascular disease is the leading cause of death among people with diabetes. Generation of oxidized LDLs and reduced nitric oxide (NO) availability because of endothelial NO synthase (eNOS) dysfunction are critical events in atherosclerotic plaque formation. Biochemical mechanism leading from hyperglycemia to oxLDL formation and eNOS dysfunction is unknown. RESEARCH DESIGN AND METHODS: We show that glucose, acting through oxidative stress, activates the transcription factor Foxo1 in vascular endothelial cells. RESULTS: Foxo1 promotes inducible NOS (iNOS)-dependent NO-peroxynitrite generation, which leads in turn to LDL oxidation and eNOS dysfunction. We demonstrate that Foxo1 gain-of-function mimics the effects of hyperglycemia on this process, whereas conditional Foxo1 knockout in vascular endothelial cells prevents it. CONCLUSIONS: The findings reveal a hitherto unsuspected role of the endothelial iNOS-NO-peroxynitrite pathway in lipid peroxidation and eNOS dysfunction and suggest that Foxo1 activation in response to hyperglycemia brings about proatherogenic changes in vascular endothelial cell function

Dissecting tumor metabolic heterogeneity : Telomerase and large cell size metabolically define a sub-population of stem-like, mitochondrial-rich, cancer cells

Tumor cell metabolic heterogeneity is thought to contribute to tumor recurrence, distant metastasis and chemo-resistance in cancer patients, driving poor clinical outcome. To better understand tumor metabolic heterogeneity, here we used the MCF7 breast cancer line as a model system to metabolically fractionate a cancer cell population. First, MCF7 cells were stably transfected with an hTERT-promoter construct driving GFP expression, as a surrogate marker of telomerase transcriptional activity. To enrich for immortal stem-like cancer cells, MCF7 cells expressing the highest levels of GFP (top 5%) were then isolated by FACS analysis. Notably, hTERT-GFP(+) MCF7 cells were significantly more efficient at forming mammospheres (i.e., stem cell activity) and showed increased mitochondrial mass and mitochondrial functional activity, all relative to hTERT-GFP(-) cells. Unbiased proteomics analysis of hTERT-GFP(+) MCF7 cells directly demonstrated the over-expression of 33 key mitochondrial proteins, 17 glycolytic enzymes, 34 ribosome-related proteins and 17 EMT markers, consistent with an anabolic cancer stem-like phenotype. Interestingly, MT-CO2 (cytochrome c oxidase subunit 2; Complex IV) expression was increased by >20-fold. As MT-CO2 is encoded by mt-DNA, this finding is indicative of increased mitochondrial biogenesis in hTERT-GFP(+) MCF7 cells. Importantly, most of these candidate biomarkers were transcriptionally over-expressed in human breast cancer epithelial cells in vivo. Similar results were obtained using cell size (forward/side scatter) to fractionate MCF7 cells. Larger stem-like cells also showed increased hTERT-GFP levels, as well as increased mitochondrial mass and function. Thus, this simple and rapid approach for the enrichment of immortal anabolic stem-like cancer cells will allow us and others to develop new prognostic biomarkers and novel anti-cancer therapies, by specifically and selectively targeting this metabolic sub-population of aggressive cancer cells. Based on our proteomics and functional analysis, FDA-approved inhibitors of protein synthesis and/or mitochondrial biogenesis, may represent novel treatment options for targeting these anabolic stem-like cancer cells