p53 alterations in recurrent squamous cell cancer of the head and neck refractory to radiotherapy

HPV status and immunohistochemical analysis of p16, p53 and PD‑L1 expression as prognostic biomarkers in patients with squamous cell anal cancer receiving definitive radiotherapy/chemoradiotherapy

Anal squamous cell carcinoma (SCC) treated with definitive radiotherapy (RT)/chemoradiotherapy (CRT) has shown high success rates, yet challenges such as treatment resistance and recurrence persist. The present study aimed to investigate the associations between immunohistochemical (IHC) evaluation, treatment response and prognosis in anal SCC. A retrospective cohort analysis included 42 patients with anal SCC treated at a single institution between 2006 and 2022. Human papillomavirus (HPV) status was determined, and the IHC analysis of p16, p53 and PD-L1 expression was conducted using formalin-fixed, paraffin-embedded biopsies. A complete response to RT/CRT was observed in 71.4% of patients. Recurrence occurred in 38.1% of cases, of which 7.1% had local-regional recurrence (LRR), 14.3% had distant recurrence (DR), and 16.7% had both LRR and DR. HPV positivity (71.4%) was significantly associated with p16 positivity. Lack of complete response was associated with HPV-negative status, p16-negative status, increased recurrence and DR. In addition, recurrence was significantly associated with p53-positive status, and p53 positivity was significantly associated with increased LRR. PD-L1 positivity, defined as a combined positive score (CPS) ≥1% was found in 73.8% of the patients, and exhibited significant associations with HPV positivity and p16 positivity. PD-L1 CPS ≥ 1% was also associated with an increased LRR. Univariate analysis revealed that age <65 years, a complete response and HPV positivity were associated with increased 5-year overall survival (OS), while a complete response, HPV positivity and p53-negative status were associated with increased 5-year disease-free survival (DFS). Multivariate analysis identified that age <65 years and HPV positivity are independent prognostic factors for 5-year OS, and a complete response and p53-negative status are independent prognostic factors for 5-year DFS. In conclusion, these findings suggust that the identification of HPV status and poor prognostic biomarkers at diagnosis may be used to guide personalized treatment strategies, with the combination of immunotherapy with standard CRT potentially providing improved outcomes.

The molecular characteristics of recurrent/metastatic HPV-positive head and neck squamous cell carcinoma: A systematic review of the literature

OBJECTIVES

About 17% of patients with human papillomavirus (HPV)-positive head and neck squamous cell carcinoma (HNSCC), which is mainly comprised of oropharyngeal SCC (OPSCC), will experience disease recurrence, which is often considered incurable when manifested at a metastatic and/or recurrent stage. We conducted a critical qualitative systematic review. Our objectives were to provide an overview of the molecular landscape of recurrent/metastatic HPV-positive HNSCC as well as novel molecular biomarkers.

DESIGN

A literature review was conducted to identify studies reporting on the molecular characteristics of recurrent/metastatic HPV-positive HNSCC, novel molecular biomarkers and treatment options. The reviews of abstracts, full articles, and revision of the included studies, followed by data extraction and quality assessment were performed by three independent assessors. All primary literature, such as retrospective, prospective, and clinical trials as well as basic research studies were considered, and the final search was conducted at the end of February 2023. The level of evidence was rated using the guidelines published by the Oxford Centre for Evidence-based Medicine and quality was assessed using the Newcastle-Ottawa Scale criteria.

RESULTS AND CONCLUSIONS

The literature search resulted in the identification of 1991 articles. A total of 181 full articles were screened, and 66 articles were included in this analysis. Several studies reported that recurrent/metastatic HPV-positive HNSCC had higher rates of TP53 mutation and were genomically similar to HPV-negative HNSCC. The detection of circulating tumour tissue-modified HPV DNA (ctHPVDNA) as a specific biomarker has shown promising results for monitoring treatment response and recurrence in the subset of HPV-positive HNSCC. In addition, evidence for targeted therapy in recurrent/metastatic HPV-positive HNSCC has emerged, including agents that inhibit overexpressed EGFR. Studies of combination immunotherapy are also underway. Our review outlines the latest evidence on the distinct molecular profiles of recurrent/metastatic HPV-positive HNSCC as well as the clinical potential of ctHPVDNA testing in routine practice. More controlled and longitudinal studies are needed to identify additional molecular targets and to assess the performance and benefits of novel molecular biomarkers in clinical practice.

Epithelial-to-mesenchymal transition status correlated with ultrastructural features, and TP53 mutation in patient-derived oral cancer cell lines

BACKGROUND

Oral Squamous Cell Carcinoma (OSCC) is a highly prevalent cancer in the Indian subcontinent. The major cause of mortality in OSCC patients is metastasis. Epithelial-to-mesenchymal transition (EMT) marks an important step in the metastatic process. Additionally, TP53, an important tumor suppressor gene, is also a significant determinant of the treatment outcome, and also plays a role in EMT. Therefore, understanding the interconnections between ultrastructural features, EMT status and TP53 mutational status is of vital importance.

METHODS AND RESULTS

The ultrastructure of five OSCC cell lines was visualized by transmission electron microscopy. Trans-well invasion and migration assays as well as scratch-wound assay, and the expression of various EMT-related genes were utilized to assess the EMT status of the cell lines. The TP53 exons were amplified for the ACOSC3, ACOSC4 and ACOSC16 cell lines and sequenced and the mutations in the gene were identified by sequence alignment. The TP53 mutation in the UPCI:SCC029B cell line has been previously reported, while UPCI:SCC040 has been reported to harbor a wild type TP53. The ACOSC4 cell line which showed the shortest intercellular gaps, also had the least invasive and migratory potential. Interestingly, ACOSC4 showed the highest expression of E-cadherin and the lowest expression of Vimentin, TWIST1, ZEB1, and MMPs. Additionally, TP53 gene of ACOSC4 was unmutated, whereas the ACOSC3 and ACOSC16 harbored TP53 mutations. The mutation in ACOSC3 (R196*) was also found in 7 TCGA samples. Similarly, the UPCI:SCC040 cell line that harbors a wild type TP53 showed shorter intracellular gaps.

CONCLUSIONS

Cellular migratory properties are associated with cellular ultrastructure, epithelial-to-mesenchymal transition status and the status of TP53 mutation in the genome.

Circulating tumour DNA alterations: emerging biomarker in head and neck squamous cell carcinoma

Head and Neck cancers (HNC) are a heterogeneous group of upper aero-digestive tract cancer and account for 931,922 new cases and 467,125 deaths worldwide. About 90% of these cancers are of squamous cell origin (HNSCC). HNSCC is associated with excessive tobacco and alcohol consumption and infection with oncogenic viruses. Genotyping tumour tissue to guide clinical decision-making is becoming common practice in modern oncology, but in the management of patients with HNSCC, cytopathology or histopathology of tumour tissue remains the mainstream for diagnosis and treatment planning. Due to tumour heterogeneity and the lack of access to tumour due to its anatomical location, alternative methods to evaluate tumour activities are urgently needed. Liquid biopsy approaches can overcome issues such as tumour heterogeneity, which is associated with the analysis of small tissue biopsy. In addition, liquid biopsy offers repeat biopsy sampling, even for patients with tumours with access limitations. Liquid biopsy refers to biomarkers found in body fluids, traditionally blood, that can be sampled to provide clinically valuable information on both the patient and their underlying malignancy. To date, the majority of liquid biopsy research has focused on blood-based biomarkers, such as circulating tumour DNA (ctDNA), circulating tumour cells (CTCs), and circulating microRNA. In this review, we will focus on ctDNA as a biomarker in HNSCC because of its robustness, its presence in many body fluids, adaptability to existing clinical laboratory-based technology platforms, and ease of collection and transportation. We will discuss mechanisms of ctDNA release into circulation, technological advances in the analysis of ctDNA, ctDNA as a biomarker in HNSCC management, and some of the challenges associated with translating ctDNA into clinical and future perspectives. ctDNA provides a minimally invasive method for HNSCC prognosis and disease surveillance and will pave the way in the future for personalized medicine, thereby significantly improving outcomes and reducing healthcare costs.

Everolimus downregulates STAT3/HIF-1α/VEGF pathway to inhibit angiogenesis and lymphangiogenesis in TP53 mutant head and neck squamous cell carcinoma (HNSCC)

TP53 mutant head and neck squamous cell carcinoma (HNSCC) patients exhibit poor clinical outcomes with 50-60% recurrence rates in advanced stage patients. In a recent phase II clinical trial, adjuvant therapy with everolimus (mTOR inhibitor) significantly increased 2-year progression-free survival in p53 mutated patients. TP53-driven mTOR activation in solid malignancies causes upregulation of HIF-1α and its target, downstream effector VEGF, by activating STAT3 cell signaling pathway. Here, we investigated the effects of everolimus on the STAT3/HIF-1α/VEGF pathway in TP53 mutant cell lines and xenograft models. Treatment with everolimus significantly inhibited cell growth in vitro and effectively reduced the growth of TP53 mutant xenografts in a minimal residual disease (MRD) model in nude mice. Everolimus treatment was associated with significant downregulation of STAT3/HIF-1α/VEGF pathway in both models. Further, treatment with everolimus was associated with attenuation in tumor angiogenesis and lymphangiogenesis as indicated by decreased microvessel density of vascular and lymphatic vessels in HN31 and FaDu xenografts. Everolimus downregulated the STAT3/HIF-1α/VEGF pathway to inhibit growth and in vitro tube formation of HMEC-1 (endothelial) and HMEC-1A (lymphatic endothelial) cell lines. Our studies demonstrated that everolimus inhibits the growth of TP53 mutant tumors by inhibiting angiogenesis and lymphangiogenesis through the downregulation of STAT3/HIF-1α/VEGF signaling.

p53 Modulates Radiosensitivity in Head and Neck Cancers-From Classic to Future Horizons

p53, initially considered a tumor suppressor, has been the subject of research related to cancer treatment resistance in the last 30 years. The unfavorable response to multimodal therapy and the higher recurrence rate, despite an aggressive approach, make HNSCC a research topic of interest for improving therapeutic outcomes, even if it is only the sixth most common malignancy worldwide. New advances in molecular biology and genetics include the involvement of miRNA in the control of the p53 pathway, the understanding of mechanisms such as gain/loss of function, and the development of different methods to restore p53 function, especially for HPV-negative cases. The different ratio between mutant p53 status in the primary tumor and distant metastasis originating HNSCC may serve to select the best therapeutic target for activating an abscopal effect by radiotherapy as a "booster" of the immune system. P53 may also be a key player in choosing radiotherapy fractionation regimens. Targeting any pathway involving p53, including tumor metabolism, in particular the Warburg effect, could modulate the radiosensitivity and chemo-sensitivity of head and neck cancers.

Mutated p53 in HGSC-From a Common Mutation to a Target for Therapy

Simple Summary

Ovarian high-grade serous cancer (HGSC), the most common and the deadliest subtype of epithelial ovarian cancer, is characterized by frequent mutations in the TP53 tumor suppressor gene, encoding for the p53 protein in nearly 100% of cases. This makes p53 the focus of many studies trying to understand its role in HGSC. The aim of our review paper is to provide updates on the latest findings related to the role of mutant p53 in HGSC. This includes the clinical outcomes of TP53 mutations in HGSC, upstream regulators and downstream effectors of p53, its function in the earliest stages of HGSC development and in the interplay between the tumor cells and their microenvironment. We summarize with the likelihood of p53 mutants to serve as biomarkers for early diagnosis and as targets for therapy in HGSC.

Abstract

Mutations in tumor suppressor gene TP53, encoding for the p53 protein, are the most ubiquitous genetic variation in human ovarian HGSC, the most prevalent and lethal histologic subtype of epithelial ovarian cancer (EOC). The majority of TP53 mutations are missense mutations, leading to loss of tumor suppressive function of p53 and gain of new oncogenic functions. This review presents the clinical relevance of TP53 mutations in HGSC, elaborating on several recently identified upstream regulators of mutant p53 that control its expression and downstream target genes that mediate its roles in the disease. TP53 mutations are the earliest genetic alterations during HGSC pathogenesis, and we summarize current information related to p53 function in the pathogenesis of HGSC. The role of p53 is cell autonomous, and in the interaction between cancer cells and its microenvironment. We discuss the reduction in p53 expression levels in tumor associated fibroblasts that promotes cancer progression, and the role of mutated p53 in the interaction between the tumor and its microenvironment. Lastly, we discuss the potential of TP53 mutations to serve as diagnostic biomarkers and detail some more advanced efforts to use mutated p53 as a therapeutic target in HGSC.

Characteristics and Management of TP53-Mutated Diffuse Large B-Cell Lymphoma Patients

Background/Aim

TP53 mutation is recognized as a negative prognostic factor for patients with diffuse large B-cell lymphoma (DLBCL). Here, we present the characteristics of TP53^mut DLBCL patients following investigation of the effect of a treatment approach on survival of TP53^mut DLBCL patients.

Methods

A total of 44 DLBCL patients with TP53^mut and treated with an R-CHOP regimen were included for analysis. Patients who failed to achieve a complete response (CR) to initial treatment or relapsed in the first 6 months after initial CR were deemed to have primary refractory disease.

Results

Among 44 patients harboring TP53 mutations who underwent upfront R-CHOP or R-CHOP–like treatment, 21 (47.7%) had limited-stage and 23 (52.3%) presented advanced-stage disease. Apart from the seven patients receiving upfront surgical resection, 37 had measurable disease under the R-CHOP regimen, with 59.1% (n=26) developing primary refractory disease. Seven limited-stage patients after early complete resection and one with residue resection remained event-free at median follow-up of 37 months. Multivariate analysis revealed that elevated baseline lactate dehydrogenase (LDH), extranodal involvement (two or more), Ann Arbor stage, and locoregional treatment (surgery or radiation therapy) were independent indicators for progression-free survival (PFS). After adjustment for baseline LDH and extranodal involvement, adding locoregional treatment including surgery and radiation to the R-CHOP regimen significantly improved PFS (p=0.008) and overall survival (p=0.017) in limited-stage TP53^mut DLBCL patients compared to R-CHOP–only treatment.

Conclusion

This study presents the characteristics of TP53-mutated DLBCL and implies a potential benefit of locoregional treatment in limited-stage DLBCL patients with TP53 mutations.

Clinico-pathological peculiarities of human papilloma virus driven head and neck squamous cell carcinoma: A comprehensive update

AIMS

The current article provides a detailed account of the current understanding of molecular and clinico-pathological aspects of Human papilloma virus (HPV) driven head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

The literature review included most of the landmark trials and clinical studies related to the HPV driven HNSCC.

KEY FINDINGS

HPV positive HNSCC differ distinctly from HPV negative tobacco-related HNSCC, especially in oropharyngeal region. Therefore, the American joint committee on cancer`s latest manual for classification and staging of cancer suggests a separate staging system for HPV positive oropharyngeal cancers. Despite the younger patients being affected and the high propensity for cervical metastasis, the HPV positive oropharyngeal cancers respond much better to the treatment. The association with wild type TP53 and low EGFR expression confers the favorable prognosis in HPV driven HNSCC. Since the association is not universal, we suggest checking for p53 and EGFR expression status before considering de-intensification of therapy. In addition, the presence of matted lymph nodes and five or more nodes could mean relatively poorer prognosis, and are not suitable for de-intensification of therapy. The same is also true probably with higher T stage and co-existing tobacco use. The methods for the detection of p16, HPV DNA, HPV E6/E7 mRNA, anti-E6/E7 antibodies, in tissue, in serum and in saliva of patients, along with their clinical implications are also discussed.

SIGNIFICANCE

This article provides latest developments on the HPV driven HNSCC. 'Diagnosis of transcriptionally active HPV infection,' 'Modalities for surveillance,' 'Implication of de-escalation of therapy' are some of the critical issues that could serve the medical, the research as well as the patient communities.

Absence of disruptive TP53 mutations in high-risk human papillomavirus-driven neck squamous cell carcinoma of unknown primary

BACKGROUND

To enforce the evidence for causality between high-risk human papillomavirus (hrHPV) infections and neck squamous cell carcinoma from unknown primary (NSCCUP) and provide biological basis for treatment de-intensification, we searched for TP53 mutations in association with HPV status.

METHODS

TP53 mutations were searched for by amplification of exons 4 to 10.

RESULTS

Of the 70 NSCCUP, 27 (39%) harbored HPV infection. TP53 sequencing resulted in the identification of 19 patients harboring single mutations including 16 disruptive alterations (84%). The association of TP53 mutations and HPV could be evaluated in 48 NSCCUP including those with disruptive mutation in any exon (n = 16) and those without mutations but with complete sequence of exons 4 to 9 (n = 32): no disruptive mutations were found in the 17 HPV-driven NSCCUP but in 16 of the 31 non-HPV-driven NSCCUP (P = .0002).

CONCLUSION

In a fraction of cases, NSCCUP is an HPV-driven entity harboring wild-type TP53 gene or nondisruptive TP53 mutations. HPV-driven NSCCUP might benefit from treatment de-intensification.

No Mutation Detected in Five Hot Spot Codons of the Tp53 Gene by Restriction Site Mutation Analysis in Patients with Carcinoma of the Tongue

The present study evaluated 5 of the 8 main TP53 mutation hot spots in cancer by restriction site mutation analysis and compared the results with p53 protein expression in patients with cancer of the tongue. Tumor samples from 49 patients with tongue cancer were screened for TP53 mutations in exons 5 through 8 by PCR restriction site mutation analysis and for p53 protein expression by immunohistochemistry using the DO-7 antibody. Nuclear accumulation of p53 protein was seen in 22% (11/49) of the tumors, whereas none of the patients exhibited TP53 mutations in exons 5 through 8. The observed data suggest that TP53 mutations alone are not responsible for abnormal accumulation of p53 protein in tobacco-chewing-mediated tongue carcinogenesis.

Molecular biology and immunology of head and neck cancer

In recent years, our knowledge and understanding of head and neck squamous cell carcinoma (HNSCC) has expanded dramatically. New high-throughput sequencing technologies have accelerated these discoveries since the first reports of whole-exome sequencing of HNSCC tumors in 2011. In addition, the discovery of human papillomavirus in relationship with oropharyngeal squamous cell carcinoma has shifted our molecular understanding of the disease. New investigation into the role of immune evasion in HNSCC has also led to potential novel therapies based on immune-specific systemic therapies.

Defining the genomic landscape of head and neck cancers through next-generation sequencing

Next-generation sequencing (NGS) has revolutionized the field of genomics and improved our understanding of cancer biology. Advances have been achieved by sequencing tumor DNA and using matched normal DNA to filter out germ line variants to identify cancer-specific changes. The identification of high incidences of activating mutations in head and neck squamous cell carcinoma (HNSCC) amenable to drug targeting has been made, with clear distinctions between the mutational profile of HPV-positive and HPV-negative tumors. This wealth of new understanding undoubtedly ameliorates our understanding of HNSCC cancer biology and elucidates clear targets for drug targeting which will guide future personalized medicine.

The mutational spectrum of squamous-cell carcinoma of the head and neck: targetable genetic events and clinical impact

Squamous-cell cancer of the head and neck (SCCHN) represents a heterogeneous disease entity, with various etiological factors implicated in the genesis of distinct molecular subsets of tumors, which exhibit different biological and clinical behavior. Treatment of SCCHN is expected to change in the next decade as targeted therapies continue to make strides. Recently, next-generation sequencing studies conducted on ∼190 SCCHN specimens shed light into the molecular pathogenesis of the disease. These studies discovered mutations in genes involved in the differentiation program of squamous epithelium and the Notch/p63 axis (such as NOTCH1, TP63 and FBXW7), and validated genetic alterations derived from previous studies (such as mutations in TP53, CDKN2A, PIK3CA, CCND1 and HRAS) as driver genetic events in SCCHN neoplastic transformation. More recently, comprehensive data from The Cancer Genome Atlas (TCGA) project on 306 SCCHN specimens provided further insight into SCCHN inherent molecular complexity, identifying novel significantly mutated genes, including FAT1, MLL2, TGFRBR2, HLA-A, NFE2l2 and CASP8. In this article, we provide an overview of the mutational spectrum of SCCHN, with emphasis on the clinical implementation of this knowledge. We also discuss the potential integration of new data within the framework of precision cancer medicine.

Therapeutic efficacy of p53 restoration in Mdm2-overexpressing tumors

The p53 (TP53) tumor suppressor is the most frequently mutated gene in human cancers. Restoring expression of wild-type p53 has led to tumor growth suppression in a variety of tumor models that are p53 deficient. Other mechanisms, for example, upregulation of Mdm2, exist in tumors to inactivate the p53 pathway. Mdm2, an E3 ubiquitin ligase that targets p53 for proteasomal degradation, is present at high levels in many tumors with wild-type p53. In this study, the effects of restoring p53 activity were probed in Mdm2-overexpressing tumors genetically using animal models. Here, it was demonstrated that elevated levels of Mdm2 and decreased levels of p53 act additively to dampen p53 activity in DNA damage response and tumor development. Our data further indicate that restoration of wild-type p53 expression in Mdm2-overexpressing angiosarcomas results in tumor stasis and regression in some cases. Finally, it was determined that restored p53 suppressed cell proliferation but did not elicit apoptosis in the Mdm2-overexpressing angiosarcomas.

IMPLICATIONS

Restoration of wild-type p53 expression in Mdm2-overexpressing tumors suppresses tumor growth, which represents a potential clinical strategy to treat tumors with high levels of Mdm2.

Oral cavity and oropharyngeal squamous cell carcinoma genomics

Recent technological advances now permit the study of the entire cancer genome, which can elucidate complex pathway interactions that are not apparent at the level of single genes. In this review, the authors describe innovations that have allowed for whole-exome/genome analysis of genetic and epigenetic alterations and of changes in gene expression. Studies using next-generation sequencing, array comparative genomic hybridization, methylation arrays, and gene expression profiling are reviewed, with a particular focus on findings from recent whole-exome sequencing projects. A discussion of the implications of these data on treatment and future goals for cancer genomics is included.

Loss of p53 in stromal fibroblasts promotes epithelial cell invasion through redox-mediated ICAM1 signal

Tumor microenvironment plays a major role in cancer development. Understanding how the stroma affects epithelial transformation will provide a basis for new preventive strategies. Recent evidence suggests that oxidative stress in stroma may play a role in cancer progression, and loss of p53 function in the stromal cells was associated with poor prognosis and high tumor recurrence. However, the underlying mechanisms remain poorly understood. Here, we investigated the role of p53 loss in fibroblasts in epithelial transformation and the mechanistic involvement of reactive species. Using 3D organotypic culture and other assays, we report that the stroma containing p53-deficient fibroblasts could induce the nontumorigenic epithelial cells of oral and ovarian tissue origins to become invasive through reactive nitrogen species (RNS)-mediated release of the cytokine ICAM1. The p53-deficient fibroblasts have increased RNS production and accumulation of oxidative DNA-damage products associated with specific upregulation of endothelial nitric oxide synthase (eNOS). Suppression of RNS production by siRNA of eNOS or the antioxidant NAC reduced ICAM1 expression and prevented the stroma-mediated epithelial invasion. Our study uncovers the novel mechanism by which redox alteration associated with loss of p53 in stromal fibroblasts functions as a key inducer of epithelial transformation and invasion via RNS-mediated ICAM1 signaling. Thus, the modulation of redox signaling in the microenvironment may serve as a new approach to preventing epithelial transformation and suppressing cancer invasion.

Lessons learned from next-generation sequencing in head and neck cancer

Scientific innovation has enabled whole exome capture and massively parallel sequencing of cancer genomes. In head and neck cancer, next-generation sequencing has granted us further understanding of the mutational spectrum of squamous cell carcinoma. As a result of these new technologies, frequently occurring mutations were identified in NOTCH1, a gene that had not previously been implicated in head and neck cancer. The current review describes the most common mutations in head and neck cancer: TP53, NOTCH1, HRAS, PIK3CA, and CDKN2A. Emphasis is placed on the involved cellular pathways, clinical correlations, and potential therapeutic interventions. Additionally, the implications of human papillomavirus on mutation patterns are discussed.

Molecular imaging of MDM2 messenger RNA with 99mTc-labeled antisense oligonucleotides in experimental human breast cancer xenografts

The mouse double-minute 2 (MDM2) oncogene, amplified or overexpressed in many human cancers, has been suggested to be a novel target for cancer therapy. Visualization of MDM2 expression using radionuclide targeting can provide important diagnostic information in malignant tumors. The overall aim of this study was to evaluate whether liposome-coated (99m)Tc-radiolabeled antisense oligonucleotides (ASONs) targeting MDM2 messenger RNA (mRNA) could be used for imaging of MDM2 expression in vivo.

METHODS

ASON and mismatch oligonucleotide (ASONM) targeted to MDM2 mRNA were synthesized and radiolabeled with (99m)Tc using the bifunctional chelator hydrazinonicotinamide (HYNIC). Then the radiolabeled probe was characterized in vitro. Reverse-transcriptase polymerase chain reaction and Western blotting were performed to assay the MDM2 mRNA and protein level after MCF-7 (human breast adenocarcinoma cell line) cells were incubated with liposome-coated (99m)Tc-HYNIC-ASON/ASONM at various concentrations for 24 h. Following established MCF-7-bearing nude mice models, the biodistribution of liposome-coated (99m)Tc-HYNIC-ASON/ASONM was investigated, and in vivo tumor scintigraphic images were acquired for these animal models. All data were analyzed by statistical software.

RESULTS

The labeling efficiencies of (99m)Tc-HYNIC-ASON and (99m)Tc-HYNIC-ASONM were 57.2% ± 2.98% and 56.3% ± 3.01%, respectively; the specific activities were 1,450 ± 60.2 and 1,370 ± 55.4 kBq/μg, respectively; and the radiochemical purity for both was above 95%. The radiolabeled ASON still had the ability to hybridize to the sense oligonucleotide. In comparison with the mismatch probe, the antisense probe had an obvious effect on the levels of MDM2 mRNA and protein. The levels of mRNA and protein were significantly different for different concentration antisense probe groups (P < 0.01). The excretion of the antisense and mismatch probe was mainly through the liver and kidneys. The tumor radioactivity uptake of the antisense probe was significantly higher than that of the mismatch probe (P < 0.01). At 1-10 h after injection of the antisense probe, the tumor could be clearly visualized, whereas the tumors were not imaged at any time after injection of the mismatch probe.

CONCLUSION

The accumulation of liposome-coated (99m)Tc-labeled ASONs in breast cancer tissue is specific. The antisense imaging with liposome-coated (99m)Tc-HYNIC-ASON may be a promising method for visualization of MDM2 expression in human breast cancer.

Head and Neck Squamous Cell Cancer: Biology (II) and Translational Methods

The essential steps implicated in carcinogenesis are acquisition of autonomous proliferative signaling; inhibition of growth inhibitory signals; evasion of apoptosis; immortalization; angiogenesis; tissue invasion and metastasis. A considerable progress in understanding the process of carcinogenesis has further stimulated the high throughput translational methods and systems biology approach to revolutionize this field of cancer biology. The era of molecular targeted therapy has dawned and would soon replace the more 'toxic' classical 'broad-spectrum' cancer chemotherapy. This review summarises the steps of carcinogenesis and the concepts involved in translational methods, systems-biology and molecular targeted therapy.

Radiosensitization by antisense anti-MDM2 mixed-backbone oligonucleotide in in vitro and in vivo human cancer models

PURPOSE

The MDM2 oncogene, amplified or overexpressed in many human cancers, has been suggested to be a novel target for cancer therapy. We have demonstrated a second-generation antisense antihuman-MDM2 oligonucleotide to have antitumor activity when administered alone or in combination with cancer chemotherapeutic agents. In the present study, we investigated the effect of the antisense oligonucleotide on radiation therapy.

EXPERIMENTAL DESIGN

The in vitro radiosensitization activity was determined in cell lines of human cancers of prostate (LNCaP and PC3), breast (MCF-7 and MDA-MB-468), pancreas (PANC-1), and glioma (U87-MG and A172) and its in vivo radiosensitization activity in xenograft models of LNCaP, PC3, MCF-7, MDA-MB-468, and PANC-1.

RESULTS

In cells containing at least one functional p53 allele (LNCaP, U87-MG, and A172), after specific inhibition of MDM2 expression, p53 and p21 levels were elevated. In LNCaP cells, the Bax level was increased, and Bcl-2 and E2F1 levels were decreased. In PC3 cells that are p53 null, after inhibition of MDM2 expression, Bax and p21 levels were elevated, and E2F1 levels were decreased. On the basis of in vitro clonogenic assay, the antisense oligonucleotide, in a sequence-specific manner, significantly increased radiation-induced antiproliferation effects. It also increased radiation-induced inhibitory effects on tumor growth in SCID or nude mice bearing LNCaP, PC3, MCF-7, MDA-MB-468, and PANC-1 xenografts.

CONCLUSIONS

These results suggest that MDM2 has a role in radiation therapy of human cancers, regardless of p53 status, providing a basis for future development of MDM2 inhibitors, such as antisense oligonucleotides, as radiosensitizers.

Chemosensitization and radiosensitization of human cancer by antisense anti-MDM2 oligonucleotides: in vitro and in vivo activities and mechanisms

MDM2 oncogene is overexpressed in many human cancers including breast, colon, and prostate cancer, and MDM2 levels are associated with poor prognosis in patients with cancer. Here, we summarize the investigation of the functions of MDM2 oncogene in human cancer growth and the value of MDM2 as a drug target for prostate cancer therapy by using antisense to inhibit MDM2 expression. Antisense anti-human-MDM2 oligonucleotides and mismatch controls were tested in in vitro and in vivo human cancer models for antitumor activity. Targeted gene products and related proteins were analyzed and the antitumor activity was determined when the oligonucleotides were used alone or in combination with cancer chemotherapeutics and radiation therapy. The antisense oligonucleotide specifically inhibited MDM2 expression in a dose- and time-dependent manner, resulting in significant antitumor activity in vitro and in vivo. The antisense oligonucleotides also potentiated the effects of p53 activation and p21 induction by chemotherapeutic agents 10-hydroxycamptothecin, adriamycin, 5-fluorouracil, and paclitaxel. In a dose-dependent manner, the antisense oligonucleotide showed antitumor activity in nude mice bearing human cancer xenografts and increased therapeutic effectiveness of the chemotherapeutic agents irinotecan, paclitaxel, and Rituxan and radiation therapy. These results indicate that MDM2 has a role in various tumor growth through both p53-dependent and p53-independent mechanisms, indicating that MDM2 inhibitors have a broad spectrum of antitumor activities in human cancers regardless of p53 status. These results provide a basis for clinical evaluation of antisense anti-MDM2 oligonucleotides as chemosensitizer and radiosensitizer.

Radiochemotherapy in head and neck cancer

The present paper is based on a talk given, during the meeting of the EORTC Radiotherapy Group, held in Arona (Italy) on April 19-20, 2002. This review analyses many still open questions on combined chemotherapy and radiotherapy in head and neck cancer, on the basis of the available data. The paper may help to point out future directions for novel clinical researches on combined chemotherapy and radiotherapy in head and neck cancer.

The p53 network in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and, despite advances in treatment, still represents a clinical challenge. Inactivation of one or more components of the p53 network is an extremely common event in human neoplasia. In HNSCC, disabling of p53 occurs in a high proportion of cases by mutation in the p53 gene, but other mechanisms of inactivation, such as the presence of human papillomavirus (HPV) and molecular abnormalities in other components of the pathway, are also recognised. The frequent changes occurring in the p53 pathway in HNSCC imply that molecular genetic and immunocytochemical analysis of this critical tumour suppressor network may be of diagnostic and prognostic utility in the clinical management of HNSCC. Further, these changes also provide targets for the development of novel therapeutic approaches to this increasingly common cancer, in which clinical cure for advanced disease remains an elusive goal.

Expression of Ku86 confers favorable outcome of tonsillar carcinoma treated with radiotherapy

BACKGROUND

To determine possible molecular markers for predicting radiosensitivity in squamous cell carcinoma, we have examined the relationship between pretreatment expression of the DNA damage recognition complex DNA-PK, its in vitro substrates, p53 and MDM2, local tumor control after radiotherapy (RT), and patient survival.

METHODS AND MATERIALS

Formalin-fixed tumor biopsy specimens from 79 previously untreated patients with tonsillar carcinoma were analyzed by immunohistochemical methods.

RESULTS

Tumors expressing high levels of Ku86 had better locoregional control in contrast to tumors expressing low levels of Ku86 (p =.023). Survival of patients with tumors expressing high levels of DNA-PKcs was significantly better than survival of patients with tumors expressing low levels of DNA-PKcs (p =.0024). p53 and MDM2 status alone did not correlate with survival of patients. However, patients with p53 tumors and high DNA-PKcs expression had significantly better survival than patients with p53+ tumors expressing low levels of DNA-PKcs (p =.0018). Furthermore, survival of patients with high expression of DNA-PKcs or Ku86 and low MDM2 levels was significantly better when compared with survival of patients with low DNA-PKcs or Ku86 and high MDM2 (p =.0017 and p =.0034, respectively).

CONCLUSIONS

High expression of DNA-PKcs/Ku86 in combination with p53 negativity in tonsillar carcinoma correlates with better survival of patients. Identifying tumors with a phenotype predicting poor survival may be used to optimize treatment of patients with radioresistant tumors.

A lack of association between p53 mutations and recurrent nasopharyngeal carcinomas refractory to radiotherapy

OBJECTIVE

The object of this study was to determine the incidence of p53 mutation in recurrent nasopharyngeal carcinoma refractory to radiotherapy.

STUDY DESIGN

Prospective study.

METHODS

There were 31 patients enrolled in this study between 1995 and 1998. All patients had received radiotherapy but none of them had undergone chemotherapy or local salvage surgery previously.

RESULTS

The p53 status of each tumor was analyzed by polymerase chain reaction and by sequencing of exons 5 to 8 (codons 126-306). Five (16.1%) of 31 patients had mutations in the p53 gene, of which 2 were non-sense mutations, 2 were transition mutations, and 1 was a frameshift deletion mutation. The majority of the p53 mutations were found in exon 5. There is no significant difference in the incidence of p53 mutation compared with that of the previous reports for the primary disease. Based on the clinicopathologic data, there was no specific difference found between these 5 patients and the others.

CONCLUSIONS

This study shows that p53 mutation is an infrequent event and may have no essential role in recurrent nasopharyngeal carcinomas.

Splicing mutations in TP53 in human squamous cell carcinoma lines influence immunohistochemical detection

The mutational status of the tumor suppressor gene TP53 is often examined by immunohistochemistry. We compared the incidence of TP53 mutations in 12 permanent squamous cell carcinoma lines of the head and neck with the immunohistochemical staining obtained with two different antibodies. The mutational status of the TP53 gene was assessed by sequencing the complete coding frame of the TP53 mRNA. All 12 tumor cell lines had TP53 mutations. Six of them showed missense mutations and five had premature stop codons caused either by splicing mutations or nonsense mutations or by exon skipping. One tumor cell line was heterozygous, with a truncating splicing mutation and an additional missense mutation located on different alleles. In one case, an in-frame insertion of 23 extra codons was found. All missense mutations were positive in immunhistochemistry and Western blotting. The truncated p53 was not immunohistochemically detected in three cases with the DO-7 antibody and in five cases with the G59-12 antibody, giving false-negative results in 25% or 40%, respectively, of all tumor cell lines examined. We conclude that splicing mutations are common in squamous cell carcinoma lines and that the incidence of p53 inactiviation by erroneous splicing is higher than yet reported. Sequencing of only the exons of TP53 may miss intronic mutations leading to missplicing and may therefore systematically underestimate the TP53 mutation frequency.

Oncolytic virotherapy for cancer with the adenovirus dl1520 (Onyx-015): results of phase I and II trials

Replication-selective viral agents hold promise as a novel cancer treatment platform (virotherapy). dl1520 (Onyx-015, now CI-1042, Pfizer Corp., Groton, CT, USA), an E1B-55kD gene-deleted adenovirus, was the first such genetically engineered agent to be tested in humans. Over 250 cancer patients have now been treated on approximately ten clinical trials (phase I-III). The virus was generally well tolerated at doses of up to 2 x 10(12) particles by intratumoural, intraperitoneal, hepatic arterial and i.v. administration; no maximally-tolerated doses were identified following intra-vascular administration. Viral replication was tumour-selective and was documented after administration by all routes; however, viral replication was variable depending on tumour histology. Single agent efficacy has been relatively limited to date (0-14% local tumour regression rates). In combination with chemotherapy, however, encouraging antitumoural activity has been demonstrated. These clinical research results demonstrate the potential of this novel treatment platform, as well as the hurdles to be overcome. Novel replication-selective agents with improved potency are being developed.

Human papillomavirus-associated head and neck squamous cell carcinoma: mounting evidence for an etiologic role for human papillomavirus in a subset of head and neck cancers

There is increasing molecular and epidemiologic evidence that human papillomavirus (HPV) is associated with a distinct subset of head and neck squamous cell carcinomas. The strength and consistency of HPV DNA presence in oropharyngeal cancers bolster the argument that this association is likely causal. HPV-positive tonsillar cancer in particular is emerging as a specific disease entity with distinct molecular, pathologic, and clinical characteristics. Recent data suggest that the incidence of tonsillar carcinoma in the United States is increasing, despite a decline in tobacco use, supporting the existence of other important risk factors such as HPV infection. Individuals with a history of an HPV-associated anogenital cancer and HIV-infected men are at increased risk for tonsillar carcinoma. This review focuses on the recent literature (since 1998) investigating the relationship between HPV and head and neck cancer development, using the current paradigm for causal inference in epidemiologic research attributed to Sir A. Bradford Hill. Data examining the association of HPV with pathogenesis of head and neck squamous cell carcinoma before 1999 were previously reviewed in this journal.

TP53 mutation is related to poor prognosis after radiotherapy, but not surgery, in squamous cell carcinoma of the head and neck

BACKGROUND AND METHODS

TP53 gene-mutation and expression of p53 have been described to influence the radiosensitivity of tumour cells from head and neck carcinomas. The present study was performed to evaluate whether TP53 mutation may influence the clinical outcome of head and neck cancer patients treated with radiotherapy or surgery.

MATERIALS AND METHODS

DNA was extracted from formalin-fixed paraffin-embedded tissue sections from primary biopsies taken before radiotherapy. Gene mutations (in exons 5-9) were identified using denaturing gradient gel electrophoresis (DGGE) as the initial scanning procedure and characterized by sequencing. Patients were treated with primary radiotherapy or surgery alone. Treatment was given according to the DAHANCA schedules with 5 or 6 weekly fractions (2 Gy) of radiotherapy (66-68 Gy). Most patients were also treated with the hypoxic radiosensitizer Nimorazole. The results are reported as 5-year actuarial values, and differences estimated by log-rank analysis.

RESULTS

The present analysis is based on 114 patients with squamous cell carcinoma of the larynx, pharynx and oral cavity diagnosed between March 1992 and October 1996. Ninety patients received primary radiotherapy alone and 21 were treated with surgery. TP53 mutations were found in 45 patients (39%) and in patients receiving radiotherapy, TP53 mutation was highly associated with poor prognosis. Loco-regional control rates (5-year actuarial values) for TP53 mutation was 29 vs. 54% for TP53 wildtype (P < 0.01). For disease-free survival the corresponding values were 13 and 38% (P < 0.01), respectively. The correlations were not found to be related to specific subtypes of mutations (e.g. missense mutations affecting DNA-contact or Zn-binding regions) but rather to the presence of any mutation at all. In contrast, TP53 mutation did not influence the response to surgery.

CONCLUSIONS

A strong relationship was observed between TP53 mutation and poor prognosis (increased risk of loco-regional failure and death) in head and neck cancer patients given primary radiotherapy but not surgery.

Clinical research results with dl1520 (Onyx-015), a replication-selective adenovirus for the treatment of cancer: what have we learned?

Replication-selective microbial agents hold promise as a novel cancer treatment platform. dl1520 (Onyx-015), an E1B-55 kD gene-deleted adenovirus, was the first such genetically engineered agent to be tested in humans. Over 200 cancer patients have been treated to date on over 10 clinical trials (phases I-III). The virus was generally well-tolerated at doses of up to 2 x 10(12) particles by intratumoral, intraperitoneal, hepatic arterial and intravenous administration; no maximally tolerated doses were identified by any route of administration. Viral replication was tumor-selective, and was documented after administration by all routes; replication was generally transient (<10 days), however, and was variable depending on tumor histology. single agent efficacy has been limited to date (0-14% local tumor regression rates). in combination with chemotherapy, however, encouraging antitumoral activity has been demonstrated. these clinical research results demonstrate the potential of this novel treatment platform, as well as the hurdles to be overcome. novel replication-selective agents with improved potency are needed.

Genetic alterations in head and neck cancer: interactions among environmental carcinogens, cell cycle control, and host DNA repair

Head and neck squamous cell carcinomas (HNSCC) arise as a consequence of cumulative genetic changes brought about by continued exposure to carcinogens associated with tobacco and alcohol use, influenced by viral agents such as human papillomaviruses, in a background of acquired or heritable genetic susceptibility. The presence of widespread genomic instability in HNSCC, such as cytogenetic aberrations, allelic imbalance/loss of heterozygosity, and microsatellite instability, suggests that there is an imperfection in the host DNA repair machinery. Genomic instability with progressive accumulation of detrimental genetic alterations appears to be dependent upon a circuitous interaction between the environmental genotoxic insults and the host DNA repair machinery, the functional integrity of which is governed by the proper cell cycle control and host DNA repair capacity. Thus, it can be hypothesized that continued exposure to environmental carcinogens (ie, longstanding history of smoking and drinking), loss of proper cell cycle control (eg, inactivation of p53 or p16 tumor suppressor genes or amplification of the proto-oncongene cyclin D1), and impaired DNA repair capacity (both inherited and acquired) are prerequisites in head and neck carcinogenesis.