Cancers, Volume 8, Issue 8 (August 2016) – 6 articles

Non-alcoholic fatty liver disease (NAFLD), characterized by fat accumulation in liver, is closely associated with central obesity, over-nutrition and other features of metabolic syndrome, which elevate the risk of developing hepatocellular carcinoma (HCC). The Wnt/β-catenin signaling pathway plays a significant role in the physiology and pathology of liver. Up to half of HCC patients have activation of Wnt/β-catenin signaling. However, the mutation frequencies of CTNNB1 (encoding β-catenin protein) or other antagonists targeting Wnt/β-catenin signaling are low in HCC patients, suggesting that genetic mutations are not the major factor driving abnormal β-catenin activities in HCC. Emerging evidence has demonstrated that obesity-induced metabolic pathways can deregulate chromatin modifiers such as histone deacetylase 8 to trigger undesired global epigenetic changes, thereby modifying gene expression program which contributes to oncogenic signaling. This review focuses on the aberrant epigenetic activation of Wnt/β-catenin in the development of NAFLD-associated HCC. A deeper understanding of the molecular mechanisms underlying such deregulation may shed light on the identification of novel druggable epigenetic targets for the prevention and/or treatment of HCC in obese and diabetic patients. Full article

Head and neck cancers (HNCs) are a highly heterogeneous group of tumours that are associated with diverse clinical outcomes. Recent evidence has demonstrated that human papillomavirus (HPV) is involved in up to 25% of HNCs; particularly in the oropharyngeal carcinoma (OPC) subtype where it can account for up to 60% of such cases. HPVs are double-stranded DNA viruses that infect epithelial cells; numerous HPV subtypes, including 16, 18, 31, 33, and 35, drive epithelial cell transformation and tumourigenesis. HPV positive (HPV+) HNC represents a distinct molecular and clinical entity from HPV negative (HPV−) disease; the biological basis for which remains to be fully elucidated. HPV positivity is strongly correlated with a significantly superior outcome; indicating that such tumours should have a distinct management approach. This review focuses on the recent scientific and clinical investigation of HPV+ HNC. In particular, we discuss the importance of molecular and clinical evidence for defining the role of HPV in HNC, and the clinical impact of HPV status as a biomarker for HNC. Full article

T-cell Factor/Lymphoid Enhancer Factor (TCF/LEF) transcription factors are major regulators of Wnt targets, and the products of the TCF7 and TCF7L2 genes have both been implicated in the progression of colorectal cancer in animal models and humans. TCFs recognize specific DNA sequences through their high mobility group (HMG) domains, but invertebrate TCFs and some isoforms of vertebrate TCF7 and TCF7L2 contain a second DNA binding domain known as the C-clamp. This review will cover the basic properties of C-clamps and their importance in Wnt signaling, using data from Drosophila, C. elegans, and mammalian cell culture. The connection between C-clamp containing TCFs and colorectal cancer will also be discussed. Full article

Population aging is a public health problem affecting the majority of the developed world. As populations age, the incidence of degenerative diseases increases exponentially, leading to large increases in public spending on healthcare. Here we summarize recent findings on the developmental drift theory of aging, and the links that have been established between aging and the Wnt signaling pathways. We focus on insights derived from model organisms connecting the evolutionary basis of aging and the link to developmental programming. Full article

Few studies have assessed the burden of human papillomavirus (HPV) infection in Pakistan. We aim to provide specific information on HPV-type distribution in invasive cervical cancer (ICC) in the country. A total of 280 formalin-fixed paraffin-embedded tissue blocks were consecutively selected from Shaukat Khanum Memorial Cancer Hospital and Research Centre (Lahore, Pakistan). HPV-DNA was detected by SPF10 broad-spectrum PCR followed by DNA enzyme immunoassay and genotyping by LiPA25. HPV-DNA prevalence was 87.5% (95%CI: 83.0–91.1), with 96.1% of cases histologically classified as squamous cell carcinoma. Most of the HPV-DNA positive cases presented single infections (95.9%). HPV16 was the most common type followed by HPV18 and 45. Among HPV-DNA positive, a significantly higher contribution of HPV16/18 was detected in Pakistan (78.4%; 72.7–83.3), compared to Asia (71.6%; 69.9–73.4) and worldwide (70.8%; 69.9–71.8) and a lower contribution of HPVs31/33/45/52/58 (11.1%; 7.9–15.7 vs. 19.8%; 18.3–21.3 and 18.5%; 17.7–19.3). HPV18 or HPV45 positive ICC cases were significantly younger than cases infected by HPV16 (mean age: 43.3, 44.4, 50.5 years, respectively). A routine cervical cancer screening and HPV vaccination program does not yet exist in Pakistan; however, the country could benefit from national integrated efforts for cervical cancer prevention and control. Calculated estimations based on our results show that current HPV vaccine could potentially prevent new ICC cases. Full article

Malignant brain tumors continue to represent a devastating diagnosis with no real chance for cure. Despite an increasing list of potential salvage therapies, standard-of-care for these patients has not changed in over a decade. Immunotherapy has been seen as an exciting option, with the potential to offer specific and long lasting tumor clearance. The “gold standard” in immunotherapy has been the development of a tumor-specific CD8 T cell response to potentiate tumor clearance and immunological memory. While many advances have been made in the field of immunotherapy, few therapies have seen true success. Many of the same principles used to develop immunotherapy in tumors of the peripheral organs have been applied to brain tumor immunotherapy. The immune-specialized nature of the brain should call into question whether this approach is appropriate. Recent results from our own experiments require a rethinking of current dogma. Perhaps a CD8 T cell response is not sufficient for an organ as immunologically unique as the brain. Examination of previously elucidated principles of the brain’s immune-specialized status and known immunological preferences should generate discussion and experimentation to address the failure of current therapies. Full article