Expression of pAkt affects p53 codon 72 polymorphism-based prediction of response to radiotherapy in nasopharyngeal carcinoma

Biological Adaptations of Tumor Cells to Radiation Therapy

Radiation therapy has been used worldwide for many decades as a therapeutic regimen for the treatment of different types of cancer. Just over 50% of cancer patients are treated with radiotherapy alone or with other types of antitumor therapy. Radiation can induce different types of cell damage: directly, it can induce DNA single- and double-strand breaks; indirectly, it can induce the formation of free radicals, which can interact with different components of cells, including the genome, promoting structural alterations. During treatment, radiosensitive tumor cells decrease their rate of cell proliferation through cell cycle arrest stimulated by DNA damage. Then, DNA repair mechanisms are turned on to alleviate the damage, but cell death mechanisms are activated if damage persists and cannot be repaired. Interestingly, some cells can evade apoptosis because genome damage triggers the cellular overactivation of some DNA repair pathways. Additionally, some surviving cells exposed to radiation may have alterations in the expression of tumor suppressor genes and oncogenes, enhancing different hallmarks of cancer, such as migration, invasion, and metastasis. The activation of these genetic pathways and other epigenetic and structural cellular changes in the irradiated cells and extracellular factors, such as the tumor microenvironment, is crucial in developing tumor radioresistance. The tumor microenvironment is largely responsible for the poor efficacy of antitumor therapy, tumor relapse, and poor prognosis observed in some patients. In this review, we describe strategies that tumor cells use to respond to radiation stress, adapt, and proliferate after radiotherapy, promoting the appearance of tumor radioresistance. Also, we discuss the clinical impact of radioresistance in patient outcomes. Knowledge of such cellular strategies could help the development of new clinical interventions, increasing the radiosensitization of tumor cells, improving the effectiveness of these therapies, and increasing the survival of patients.

Multiple Mechanisms Involving in Radioresistance of Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is the malignant tumor with ethnic and geographical distribution preference. Although intensity-modulated radiotherapy (IMRT)-based radiotherapy combined with chemotherapy and targeted therapy has dramatically improved the overall survival of NPC patients, there are still some patients suffering from recurrent tumors and the prognosis is poor. Multiple mechanisms may be responsible for radioresistance of NPC, such as cancer stem cells (CSCs) existence, gene mutation or aberrant expression of genes, epigenetic modification of genes, abnormal activation of certain signaling pathways, alteration of tumor microenvironment, stress granules (SGs) formation, etc. We conduct a comprehensive review of the published literatures focusing on the causes of radioresistance, retrospect the regulation mechanisms following radiation, and discuss future directions of overcoming the resistance to radiation.

A review of radiation genomics: integrating patient radiation response with genomics for personalised and targeted radiation therapy

Background

The success of radiation therapy for cancer patients is dependent on the ability to deliver a total tumouricidal radiation dose capable of eradicating all cancer cells within the clinical target volume, however, the radiation dose tolerance of the surrounding healthy tissues becomes the main dose-limiting factor. The normal tissue adverse effects following radiotherapy are common and significantly impact the quality of life of patients. The likelihood of developing these adverse effects following radiotherapy cannot be predicted based only on the radiation treatment parameters. However, there is evidence to suggest that some common genetic variants are associated with radiotherapy response and the risk of developing adverse effects. Radiation genomics is a field that has evolved in recent years investigating the association between patient genomic data and the response to radiation therapy. This field aims to identify genetic markers that are linked to individual radiosensitivity with the potential to predict the risk of developing adverse effects due to radiotherapy using patient genomic information. It also aims to determine the relative radioresponse of patients using their genetic information for the potential prediction of patient radiation treatment response.

Methods and materials

This paper reports on a review of recent studies in the field of radiation genomics investigating the association between genomic data and patients response to radiation therapy, including the investigation of the role of genetic variants on an individual’s predisposition to enhanced radiotherapy radiosensitivity or radioresponse.

Conclusion

The potential for early prediction of treatment response and patient outcome is critical in cancer patients to make decisions regarding continuation, escalation, discontinuation, and/or change in treatment options to maximise patient survival while minimising adverse effects and maintaining patients’ quality of life.

Effect of p53 codon 72 polymorphism on the survival outcome in advanced stage cervical cancer patients in India

Background & objectives:

The Arg>Pro polymorphism in codon 72 of p53 gene is known to affect the susceptibility of cervical cancer differently in different population worldwide although information regarding its role in determining survival status and disease outcome in patients is lacking. The present study was conducted to determine the genotype frequency and prognostic role of p53 codon 72 Arg>Pro polymorphism in patients with advanced stage cervical cancer in India.

Methods:

The p53 codon 72 polymorphism was determined in tumour biopsies (n = 107) and matched blood samples (n = 19) in cervical cancer patients using polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP). Effect of p53 genotype on the overall survival (OS) and recurrence-free survival (RFS) was analyzed. Individual Arg or Pro alleles were studied for their significance on survival as Pro carriers (Pro/Pro + Arg/Pro) versus Arg/Arg individuals or Arg carriers (Arg/Arg + Arg/Pro) versus Pro/Pro individuals.

Results:

The frequencies for Arg/Arg, Arg/Pro and Pro/Pro genotypes were 27.2, 49.5 and 23.3 per cent, respectively. There was no significant difference in the genotypes with respect to patients’ OS or RFS.

Interpretation & conclusions:

The findings of our study indicated that p53 codon 72 polymorphism might not be an independent marker in predicting clinical outcome in advanced stage cervical cancer patients. Further studies need to be done in larger samples to confirm these findings.

Chemoradiotherapy with weekly low-dose docetaxel and cisplatin concurrent with radiation for patients with locally advanced nasopharyngeal carcinoma, followed by adjuvant chemotherapy for selected patients

OBJECTIVE

We investigated the efficacy and safety of concurrent chemoradiotherapy using weekly low-dose docetaxel and cisplatin in patients with locally advanced nasopharyngeal carcinoma.

METHODS

This was a retrospective analysis of 31 patients who were treated with this regimen from 2001 to 2014. Concurrent chemoradiotherapy consisted of radiotherapy with a total dose of 59.4-70.2 Gy plus weekly administration of docetaxel (5-10 mg/m²) and cisplatin (20 mg/m²), up to six cycles. At least two cycles of platinum-based adjuvant chemotherapy were prescribed for Stage IV and Stage III patients with partial response or stable disease after concurrent chemoradiotherapy.

RESULTS

Of the 31 patients, 28 (90%) completed concurrent chemoradiotherapy as planned. The overall complete response and partial response rates were 42% and 52%, respectively. Seventeen of the 21 patients who were prescribed adjuvant chemotherapy underwent it. After a median follow-up of 39.1 months for the 23 surviving patients, 9 (29%) developed locoregional recurrence or progression and 6 patients (19%) developed distant metastasis. The 3-year overall survival and progression-free survival rates were 76% and 56%, respectively. Univariate analyses revealed that clinical stage was a significant predictor of complete response, overall survival and progression-free survival. The most serious adverse events were mucositis during concurrent chemoradiotherapy and neutropenia during adjuvant chemotherapy.

CONCLUSIONS

This concurrent chemoradiotherapy protocol showed practical efficacy with high feasibility and acceptable toxicity. To improve the progression-free survival of patients with Stage IV disease who are treated by this protocol, changes to their treatment strategy should be considered.

MiRNA-203 Reduces Nasopharyngeal Carcinoma Radioresistance by Targeting IL8/AKT Signaling

Radioresistance poses a major challenge in nasopharyngeal carcinoma (NPC) treatment, but little is known about how miRNA (miR) regulates this phenomenon. In this study, we investigated the function and mechanism of miR-203 in NPC radioresistance, one of downregulated miRs in the radioresistant NPC cells identified by our previous microarray analysis. We observed that miR-203 was frequently downregulated in the radioresistant NPC tissues compared with radiosensitive NPC tissues, and its decrement significantly correlated with NPC radioresistance and poor patient survival, and was an independent predictor for reduced patient survival. In vitro radioresponse assays showed that miR-203 mimic markedly decreased NPC cell radioresistance. In a mouse model, therapeutic administration of miR-203 agomir dramatically sensitized NPC xenografts to irradiation. Mechanistically, we confirmed that IL8 was a direct target of miR-203, and found that reduced miR-203 promoted NPC cell radioresistance by activating IL8/AKT signaling. Moreover, the levels of IL8 and phospho-AKT were significantly increased in the radioresistant NPC tissues compared with radiosensitive NPC tissues, and negatively associated with miR-203 level. Our data demonstrate that miR-203 is a critical determinant of NPC radioresponse, and its decrement enhances NPC radioresistance through targeting IL8/AKT signaling, highlighting the therapeutic potential of the miR-203/IL8/AKT signaling axis in NPC radiosensitization.

The long-term outcomes of alternating chemoradiotherapy for locoregionally advanced nasopharyngeal carcinoma: a multiinstitutional phase II study

To examine the long-term outcomes of alternating chemoradiotherapy (ALCRT) for patients with locoregionally advanced nasopharyngeal carcinoma (NPC) and to assess the efficacy of ALCRT for NPC. Patients with stage IIB to IVB, ECOG PS 0-2, 18-70 years-old, and sufficient organ function were eligible for this study. First, chemotherapy, consisting of 5-fluorouracil (800 mg/m(2) per 24 h on days 1-5) and cisplatin (100 mg/m(2) per 24 h on day 6), was administered, then a wide field of radiotherapy (36 Gy/20 fraction), chemotherapy, a shrinking field of radiotherapy (34 Gy/17 fraction), and chemotherapy were performed alternately. Between December 2003 and March 2006, 90 patients in 25 facilities were enrolled in this study, 87 patients were finally evaluated. A total of 67 patients (76.1%) completed the course of treatment. The overall survival and the progression-free survival rates at 5 years were 78.04% (95% CI: 69.1~87.0%), and 68.74% (95% CI: 58.8~78.7%), respectively. The long-term outcomes of ALCRT for NPC were thought to be promising. ALCRT will be considered to be a controlled trial to compare therapeutic results with those of concurrent chemoradiotherapy for NPC.

Radiogenomics helps to achieve personalized therapy by evaluating patient responses to radiation treatment

Radiogenomics is the whole genome application of radiogenetics, which focuses on uncovering the underlying genetic causes of individual variation in sensitivity to radiation. There is a growing consensus that radiosensitivity is a complex, inherited polygenic trait, dependent on the interaction of many genes involved in multiple cell processes. An understanding of the genes involved in processes such as DNA damage response and oxidative stress response, has evolved toward examination of how genetic variants, most often, single nucleotide polymorphisms (SNPs), may influence interindividual radioresponse. Many experimental approaches, such as candidate SNP association studies, genome-wide association studies and massively parallel sequencing are being proposed to address these questions. We present a review focusing on recent advances in association studies of SNPs to radiotherapy response and discuss challenges and opportunities for further studies. We also highlight the clinical perspective of radiogenomics in the future of personalized treatment in radiation oncology.

New biological markers in the decision of treatment of head and neck cancer patients

Head and neck squamous cell carcinoma is the sixth most common cancer type worldwide. Also the 5-year survival rate of less than 50 % seems to be lower than other cancer types. There are some reasons behind this high mortality rate; one of them is the lack of knowledge about the biology and genomic instability behind the carcinogenic processes. These biological features could condition the failure of frontline treatment, in which case rescue treatment should be used, representing an overtreatment for the patients. For years many biological factors have been tested as prognostic and predictive factors in relation to treatment with a modest success. To find appropriate tests which could be used in the context of the individualized treatment decision, we have reviewed new biological markers, not only in tumor tissue, but also in normal tissue from head and neck carcinoma patients.