Effect of ionising radiation on HPV-positive and HPV-negative oropharyngeal cancer cell lines

In recent decades, the incidence of human papillomavirus (HPV) associated oropharyngeal squamous cell carcinoma (OPSCC) has increased world-wide. Overall, HPV-positive OPSCC patients respond better to treatment (increased survival rate) compared to HPV-negative patients. This might be partially associated with a deficiency in repair of double-strand DNA breaks, and/or with residual p53 activity in HPV-positive tumours. However new studies, specific to HPV-positive OPSCC, are limited due to the low number of relevant OPSCC in-vitro models. The general aims of this study were to develop new HPV-positive OPSCC cell lines and use them, together with established OPSCC cell lines, to investigate responses to ionising radiation (IR). These experiments were intended to test that HPV-positive OPSCC cell lines were more sensitive to IR than HPV-negative OPSCC cell lines. Two novel OPSCC cell lines, one HPV-positive and one HPV-negative, were derived and characterised. The HPV-positive OPSCC cell lines demonstrated greater variation in radio-sensitivity compared to HPV-negative OPSCC cell lines. However, radio-sensitivity was not associated with p53 accumulation and/or cell cycle arrest. All HPV-positive OPSCC cell lines showed G2 arrest after IR, but so did several HPV-negative lines. The mRNA sequencing data confirmed expression of HPV oncogenes and integration of HPV DNA into the host genome, with an increase of integration sites after IR. Comparison of irradiated HPV-positive and HPV-negative cell lines did not show consistent differences in gene expression associated with DNA repair. The transcription of DNA repair factors did not correlate with radio-sensitivity within the HPV-positive cell lines. The study was successful in generating and characterising new OPSCC cell lines but did not find evidence that the better prognosis of HPV-positive tumours is associated with defects in DNA repair. This suggests that additional mechanisms may be responsible for the improved prognosis of HPV-positive OPSCC patients following treatment

Sensitivity of human papillomavirus-positive and -negative oropharyngeal cancer cell lines to ionizing irradiation

Human papillomavirus‑positive (HPV+) oropharyngeal squamous cell carcinoma (OPSCC) has increased in incidence and has a much better prognosis than HPV‑negative (HPV‑) OPSCC with radiotherapy alone, but exactly why is unknown. The present study therefore aimed to further examine the sensitivity and possible changes in gene expression of several HPV+ and HPV‑ OPSCC, including various novel cell lines, upon ionizing irradiation (IR). Previously established HPV+ UM‑SCC‑47, UPCI‑SCC‑90, CU‑OP‑2, CU‑OP‑3 and HPV‑ UM‑SCC‑4, UM‑SCC‑6, UM‑SCC‑74a, UM‑SCC‑19 and newly established CU‑OP‑17 and CU‑OP‑20, characterised here, were subjected to 0‑6 Gy. Surviving fractions of each cell line were tested by clonogenic assays, and irregularities in cell cycle responses were examined by flow cytometry, while changes in gene expression were followed by mRNA sequencing. HPV+ OPSCC cell lines showed greater variation in sensitivity to ionizing irradiation (IR) and tended to be more sensitive than HPV‑ OPSCC cell lines. However, their IR sensitivity was not correlated to the proportion of cells in G2 arrest, and HPV‑ cell lines generally showed lower increases in G2 after IR. Upon IR with 2 Gy, mRNA sequencing revealed an increase in minor HPV integration sites in HPV+ cell lines, and some changes in gene expression in OPSCC cell lines, but not primarily those associated with DNA repair. To conclude, HPV+ OPSCC cell lines showed greater variation in their sensitivity to IR, with some that were radioresistant, but overall the HPV+ OPSCC group still tended to be more sensitive to IR than the HPV‑ OPSCC group. In addition, HPV+ OPSCC lines were more frequently in G2 as compared to HPV‑ cell lines, but the increase in G2 arrest upon IR in HPV+ OPSCC was not correlated to sensitivity to IR. Increases in minor HPV integration sites and changes in gene expression were also demonstrated after irradiation with 2 Gy

Sensitivity to inhibition of DNA repair by Olaparib in novel oropharyngeal cancer cell lines infected with Human Papillomavirus

The incidence of Human Papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) is increasing rapidly in the UK. Patients with HPV-positive OPSCC generally show superior clinical responses relative to HPV-negative patients. We hypothesised that these superior responses could be associated with defective repair of DNA double strand breaks (DSB). The study aimed to determine whether defective DNA repair could be associated with sensitivity to inhibition of DNA repair using the PARP inhibitor Olaparib. Sensitivity to Olaparib, and induction and repair of DNA damage, were assessed in a panel of 8 OPSCC cell-lines, including 2 novel HPV-positive lines. Effects on cell cycle distribution and levels of PARP1 and p53 were quantified. RNA-sequencing was used to assess differences in activity of DNA repair pathways. Two HPV-positive OPSCC lines were sensitive to Olaparib at potentially therapeutic doses (0.1–0.5 μM). Two HPV-negative lines were sensitive at an intermediate dose. Four other lines, derived from HPV-positive and HPV-negative tumours, were resistant to PARP inhibition. Only one cell-line, UPCISCC90, showed results consistent with the original hypothesis i.e. that in HPV-positive cells, treatment with Olaparib would cause accumulation of DSB, resulting in cell cycle arrest. There was no evidence that HPV-positive tumours exhibit defective repair of DSB. However, the data suggest that a subset of OPSCC may be susceptible to PARP-inhibitor based therap

WHO/IUIS Allergen Nomenclature: Providing a common language

A systematic nomenclature for allergens originated in the early 1980s, when few protein allergens had been described. A group of scientists led by Dr. David G. Marsh developed a nomenclature based on the Linnaean taxonomy, and further established the World Health Organization/International Union of Immunological Societies (WHO/IUIS) Allergen Nomenclature Sub-Committee in 1986. Its stated aim was to standardize the names given to the antigens (allergens) that caused IgE-mediated allergies in humans. The Sub-Committee first published a revised list of allergen names in 1986, which continued to grow with rare publications until 1994. Between 1994 and 2007 the database was a text table online, then converted to a more readily updated website. The allergen list became the Allergen Nomenclature database (www.allergen.org), which currently includes approximately 880 proteins from a wide variety of sources. The Sub-Committee includes experts on clinical and molecular allergology. They review submissions of allergen candidates, using evidence-based criteria developed by the Sub-Committee. The review process assesses the biochemical analysis and the proof of allergenicity submitted, and aims to assign allergen names prior to publication. The Sub-Committee maintains and revises the database, and addresses continuous challenges as new “omics” technologies provide increasing data about potential new allergens. Most journals publishing information on new allergens require an official allergen name, which involves submission of confidential data to the WHO/IUIS Allergen Nomenclature Sub-Committee, sufficient to demonstrate binding of IgE from allergic subjects to the purified protein

Whole-exome sequencing of HPV positive tonsillar and base of tongue squamous cell carcinomas reveals a global mutational pattern along with relapse-specific somatic variants

To identify predictive/targetable markers in human papillomavirus positive (HPV+) ton-sillar and base of tongue cancer (TSCC/BOTSCC), whole-exome sequencing (WES) of tumours of patients with/without recurrence was performed. Forty primary tumours and adjacent normal tissue were separated by micro-dissection from formalin-fixed paraffin-embedded tissue from patients treated with curative intent 2000–2014 at Karolinska University Hospital. Successful sequencing was obtained in primary tumours of 18 patients without and primaries of 17 with local or distant recurrence, as well as in 10 corresponding recurrences (i.e., five local relapses and five distant metas-tases) from these 17 patients. One variant—a high-impact deletion in the CDC27 gene—was observed only in primaries of 5/17 patients that had a recurrence after full treatment but in none of those without recurrence. In addition, 3 variants and 26 mutated genes, including CDC27, BCLAF1 and AQP7, were present in at least 30% of all primary tumours independent of prognosis. To conclude, a CDC27 deletion was specific and found in ~30% of samples from patients with a local relapse/distant metastasis and could, therefore, potentially be a prospective marker to predict prognosis. Commonly mutated genes, such as BCLAF1, should be further studied in the context of targeted therapy