Quantification of telomerase activity in normal oral mucosal tissue and oral squamous cell carcinoma

[Effect of WRAP53 β Targeted Co-Inhibitory Pathways Based on Comprehensive Bioinformatics Analysis in Treating Squamous Cell Carcinoma of the Head and Neck]

Objective

To investigate the association between WD40-encoding RNA antisense to p53 ( WRAP53 β), a telomerase new core subunit, and the clinical, genomic and immune infiltration characteristics of squamous cell carcinoma of the head and neck (HNSC), and to explore for potential joint targeted therapy of HNSC.

Methods

Tumor IMmune Estimation Resource (TIMER) online modules were adopted to predict the association between WRAP53 β expression and the clinical features, oncogene, and immune infiltration of HNSC in the Cancer Genome Atlas (TCGA) cohort. Tumor Immune Single-cell Hub (TISCH) was used to analyze WRAP53 β expression at the single cell level. Analysis of the small molecule inhibitors potentially targeting WRAP53 β was carried out by Computational Analysis of REsistance (CARE). In the in vitro verification experiment, recombinant lentiviral particles with the sh WRAP53 β sequence were synthesized. Then, the oral squamous cell carcinoma cell line Cal27 (the sh WRAP53 βgroup) stably expressing sh WRAP53 β were constructed, and two control groups were set up (the shNC group consisting of Cal27 cells added with lentiviral particles containing non-specific control sequences and the Con group consisting of untreated Cal27 cells). MTT assay was done to examine the proliferation of cells in the three groups. Cellular immunofluorescence assay was done for further qualitative examination of the expression of P53 protein in the cells of the sh WRAP53 β group and the shNC group. Western blot was done to measure the expression of WRAP53β and γ-H2AX, a DNA damage protein, in the 18 th, 23 rd and 28 th passages of the sh WRAP53 β group and the shNC group. Finally, specimens of 13 cases of oral squamous cell carcinoma and 7 cases of oral mucosal inflammation were collected, and the expression of WRAP53β and γ-H2AX in the clinical specimens of oral squamous cell carcinoma was verified with immunohistochemistry.

Resluts

TIMER analysis revealed that the expression level of WRAP53 β in HNSC tissues was significantly higher than that in normal tissues. There was a significant positive correlation between WRAP53 β expression and multiple genes in the p53 pathway, including CCNB1, CCNB2 and CDK1. Although no significant correlation between WRAP53 β expression and infiltrating immune cells was found, WRAP53 β was significantly positively correlated with the inflammatory factors IFN-γ and IL23A, and negatively correlated with IL-1A and IL-6 in HPV-positive carcinoma of the head and neck. TISCH single cell sequencing datasets also showed higher expression of WRAP53 β in malignant cells, and very low or zero expression in immune cells. According to the CARE scores, the most potent WRAP53 β co-inhibitory drugs were ATM, CDK1 and MDM4 targeted inhibitors. In vitro cell experiments showed that the proliferation ability of Cal27 cells decreased significantly in the sh WRAP53 β group as compared with that of the control group between Day 5 and Day 7 ( P<0.05). Furthermore, the expression of P53 decreased significantly in the sh WRAP53 β group. As compared with the control group, the expression of WRAP53β in sh WRAP53 β group significantly decreased in the 18 th, 23 rd and 28 th passages ( P<0.05), while γ-H2AX expression only decreased in the 18 th and 28 th passages ( P<0.05) according to the results of Western blot. Clinical specimens showed rather high positive expression rate of γ-H2AX in oral squamous cell carcinoma tissues (12/13), while the expression of WRAP53β was not detected in oral mucositis samples (0/7).

Conclusions

WRAP53 β showed significantly higher expression level in HSNC, and was significantly associated with p53 pathway genes. ATM, CDK1 and MDM4 inhibitors may be potential WRAP53 β co-inhibitory agents. RNA interference of WRAP53 β expression may cause inhibition of DNA damage, thereby indicating therapeutic potential for HNSC.

Change of telomerase activity in peripheral blood of patients with head and neck squamous cell carcinoma pre and post curative treatment

BACKGROUND

There is no clinically applicable tumor marker for head and neck cancers. Telomerase is detected in approximately 90% of all malignant tumors, it may predict poor or favorable outcomes, thus being both a highly attractive biomarker and a target for the development of molecular-based cancer diagnostics, prognostics, and therapeutics.

AIM

Primary aim was to detect a change of telomerase activity before and after curative treatment.

MATERIALS AND METHODS

Patients with biopsy proven head and neck squamous cell carcinoma, stage I-IVB treated with a curative intent, performance status 0-2 and malignancy at one primary site were included in the study. Telomerase levels were tested in tissue biopsy. Plasma telomerase levels were tested at baseline, 5 days and at 3 months after treatment using ELISA.

RESULTS

Raised plasma telomerase activity was seen in all the patients with cancer at baseline. The mean plasma telomerase level at baseline was 861.4522 ng/ml, at 5 days after completion of curative treatment was 928.92 ng/ml and at 3 months of follow up was 898.87 ng/ml. The mean tissue biopsy telomerase level was 19768.53 ng/mg. There was a significant increase in baseline telomerase levels in cancer patients compared to normals (volunteers) (t = -3.52, p = 0.001).There was a significant increase in plasma levels of telomerase at 3 months compared to baseline values (z = -1.98, p = 0.04). The increase in telomerase level did not correlate with the response of the treatment.

CONCLUSION

In patients with head and neck squamous cell carcinomas treated with a curative intent, the change in levels of telomerase correlates neither with the disease status nor with prognostic factors.

Raising the bar in anticancer therapy: recent advances in, and perspectives on, telomerase inhibitors

Telomerase is a ribonucleic reverse transcriptase enzyme that uses an integral RNA component as a template to add tandem telomeric DNA repeats, TTAGGG, at the 3' end of the chromosomes. 85-90% of human tumors and their derived cell lines predominantly express high levels of telomerase, therefore contributing to cancer cell development. However, in normal cells, telomerase activity is almost always absent except in germ cells and stem cells. This differential expression has been exploited to develop highly specific and potent cancer therapeutics. In this review, we outline recent advances in the development of telomerase inhibitors as anticancer agents.