Re-irradiation of metastatic disease in the neck from xeroderma pigmentosum

Background

Xeroderma pigmentosum, an autosomal recessive disease that occurs with a frequency of 1:250,000, is caused by a genetic defect in nucleotide excision repair enzymes. Mutation of these enzymes leads to the development of multiple basal cell and squamous cell carcinomas.

Objectives

We present a case of xeroderma pigmentosum in a patient with cervical and intraparotid metastatic disease from recurrent cutaneous squamous cell carcinomas of the face and scalp, treated with neck dissection and re-irradiation. With the illustrative case report, we include a literature review of diagnosis, prognostic factors, and treatment, with emphasis on surgical and radiation treatment of cervical metastatic disease from recurrent skin carcinomas.

Case Presentation

A xeroderma pigmentosum patient presented to our clinic with a 2-cm right submental and 1-cm right infra-auricular mass after resection of multiple squamous cell carcinomas of the scalp and face, and external-beam radiation therapy to the right face and neck. Fine-needle aspiration biopsy of the submental mass revealed poorly differentiated squamous cell carcinoma. The patient was brought to the operating room for a right modified radical neck dissection and excision of the right submental and intraparotid mass. Surgical pathology revealed 3 level ia and supraclavicular lymph nodes that were positive for metastatic squamous cell carcinoma. Re-irradiation to the entire right hemi-neck and left submandibular nodal region was performed using opposed oblique portals for the upper neck and a low anterior en face hemi-neck portal. The left parotid region was also included in the re-irradiation volume. Treatment was completed without delayed complications or recurrences to date.

Conclusions

To our knowledge, this is the first case report in the literature of a patient with xeroderma pigmentosum who subsequently developed metastatic disease from recurrent cutaneous squamous cell carcinoma. Because of the rarity of xeroderma pigmentosum, this case report is also the first to describe re-irradiation to treat cervical and intraparotid metastatic disease in a xeroderma pigmentosum patient.     

Prevalence of human papillomavirus in skin tumors from repair deficient xeroderma pigmentosum patients

The predisposition to skin cancers in childhood is the hallmark of xeroderma pigmentosum (XP), a rare autosomal recessive disorder, deficient in DNA repair and hypersensitive to ultraviolet irradiation. Human papillomavirus (HPVs), are common infections of the skin which are often found associated to benign lesions and non-melanoma skin cancers (NMSC), mainly squamous cell carcinomas (SCC) and basal cell carcinomas (BCC). Our study is the first to analyse 40 SCCs, 27 BCCs and nine normal skin biopsies from XP patients for HPV DNA which are found more frequently in SCCs (20/40) than in BCCs (4/27) or normal skin (2/9). The HPV spectrum includes 22 different epidermodysplasia verruciformis (EV) HPV types, which predominate in SCCs (48%) compared to BCCs (15%) and normal skin (22%). Our data, showing an association between EV HPV and SCCs from young XP patients is comparable to that found for NMSC from adult immunosuppressed organ transplant patients and raises the question of the importance of HPV infection in skin carcinogenesis.     

Far less frequent mutations in ras genes than in the p53 gene in skin tumors of xeroderma pigmentosum patients

Mutations in Ha-ras, and n-rasNras genes in squamous and basal cell carcinomas in patients with xeroderma Pigmentosum (XP) were examined by the polymerase chain reaction followed by single-strand conformation polymorphism analysis and direct base sequencing. No mutation was detected in codons 12, 13, and 61 of the ras genes in XP skin tumors. This was in contrast with previous findings of a high frequency of mutation in the p53 gene in skin tumors in XP patients. A novel mutation in codon 6 of the ki-ras gene was detected in a squamous cell carcinoma. The mutation was a C→T transtion at a dipyrimidine (5′-CT) sequence and could have been produced by solar ultraviolet light. The mutated ras gene did not have the ability to transform NIH/3T3 cells. In three tumors, multiple base substitutions were detected in exon 1 of the Ki-ras and N-ras genes. These results and our previous work on p53 gene mutations suggest that mutations in ras genes are far less frequent than in the p53 gene in the skin tumors in XP patients and that ras genes are less important in skin tumorigenesis in XP patients that is the p53 gene.     

The emerging role of DNA repair proteins as predictive, prognostic and therapeutic targets in cancer

Advanced cancer is the second leading cause of death in the western world. Chemotherapy and radiation are the two main treatment modalities currently available to improve patient outcomes, but treatment related toxicity and the emergence of resistance limit their effectiveness. Hence there is an urgent need to develop novel treatment strategies. Rapid advances in cancer biology have identified key pathways involved in the repair of DNA damage induced by chemotherapeutic agents and irradiation. Efficient DNA repair in the cancer cell is an important mechanism for therapeutic resistance. Up to 130 genes have been identified that are associated with human DNA repair. Several of these proteins are emerging as important predictive and prognostic factors in solid tumours. Inhibition of DNA repair has the potential to enhance the efficacy of currently available DNA damaging agents. In recent years, several promising drug targets have been identified and novel drugs synthesised that target specific DNA repair proteins. These agents have shown impressive anti-cancer effects in preclinical studies in combination with chemotherapy or irradiation. Their role in human cancer is now being investigated in early phase clinical trials in combination with chemotherapy. MGMT inhibitors, PARP inhibitors and methoxyamine are currently in early stages of clinical development. Innovative clinical trial designs are essential to evaluate the potential of DNA repair inhibitor in cancer therapy.     

Role of activator protein-1 and methylation function in 12-O-tetradecanoylphorbol-13-acetate--mediated inhibition of differentiation of Friend erythroleukemia cells.

Friend erythroleukemia cells (FELCs) differentiate after hexamethylene-bis-acetamide treatment. This differentiation is characterized by an increase in beta-globin gene expression that is followed by appearance of the hemoglobin. Phorbol-ester tumor promoters, such as 12-O-tetradecanoylphorbol-13-acetate (TPA), inhibit differentiation of TPA-sensitive cells but not TPA-resistant cells. We have shown that the increase in beta-globin expression is inhibited by TPA in a TPA-sensitive clone but not in a TPA-resistant clone. To study the molecular mechanisms of regulation of gene expression by TPA, we examined the possible involvement of gene methylation and the TPA-responsive element (TRE). Both clones showed similar patterns of methylation around the beta-globin gene. Moreover, TPA-induced TRE binding and TRE enhancer activity were similar in both variants. These results suggest that the TPA inhibition of induced differentiation may not be explained by regulation of the methylation state. The activator protein-1 also does not play a crucial role in the sensitivity of FELCs to TPA.     

Targeting human apurinic/apyrimidinic endonuclease 1 (APE1) in phosphatase and tensin homolog (PTEN) deficient melanoma cells for personalized therapy

Phosphatase and tensin homolog (PTEN) loss is associated with genomic instability. APE1 is a key player in DNA base excision repair (BER) and an emerging drug target in cancer. We have developed small molecule inhibitors against APE1 repair nuclease activity. In the current study we explored a synthetic lethal relationship between PTEN and APE1 in melanoma. Clinicopathological significance of PTEN mRNA and APE1 mRNA expression was investigated in 191 human melanomas. Preclinically, PTEN-deficient BRAF-mutated (UACC62, HT144, and SKMel28), PTEN-proficient BRAF-wildtype (MeWo), and doxycycline-inducible PTEN-knockout BRAF-wildtype MeWo melanoma cells were DNA repair expression profiled and investigated for synthetic lethality using a panel of four prototypical APE1 inhibitors. In human tumours, low PTEN mRNA and high APE1 mRNA was significantly associated with reduced relapse free and overall survival. Pre-clinically, compared to PTEN-proficient cells, PTEN-deficient cells displayed impaired expression of genes involved in DNA double strand break (DSB) repair. Synthetic lethality in PTEN-deficient cells was evidenced by increased sensitivity, accumulation of DSBs and induction of apoptosis following treatment with APE1 inhibitors. We conclude that PTEN deficiency is not only a promising biomarker in melanoma, but can also be targeted by a synthetic lethality strategy using inhibitors of BER, such as those targeting APE1.     

ATM-dependent phosphorylation of 53BP1 in response to genomic stress in oxic and hypoxic cells

The ATM kinase is activated by chromatin modification following exogenous and endogenous DSBs or cell stress, including acute anoxia. The p53 binding protein 1 (53BP1) contains multiple ATM-consensus phosphorylation sites in its N- and C-termini and may therefore be a distal read-out of ATM function. We have examined the cellular activation of these phosphorylation sites for the first time in situ following anoxic/hypoxic stress and IR-induced exogenous DSBs. We show that multiple residues of 53BP1 are phosphorylated and that these phosphoforms form discrete nuclear foci following IR or during DNA replication as exogenous or endogenous DNA double strand breaks (DSBs), respectively. Novel data pertaining to the phosphorylation of 53BP1^Ser25in situ supports its dependency on the ATM kinase; but this occurs independently of p53 function. We show that 53BP1^Ser25 is activated specifically in S-phase cells during anoxia in an ATM-dependent manner. Exogenous DSBs form discrete IR-induced foci whereas oxygen stress induced non-localized 53BP1^Ser25 activation. Our in vitro data are supported by irradiated xenograft studies in vivo whereby 53BP1^Ser25 phosphorylation does not occur in sub-regions positive for the hypoxia marker EF5. We propose a model whereby DSBs induce chromatin modification at sites of DNA damage which are tracked by the ATM substrates γ H2AX and 53BP1^Ser25 in a mechanism distinct from p53-mediated cell cycle arrest. Together this work indicates 53BP1^Ser25, and possibly other 53BP1 phosphoforms, as a bona fide DSB-biomarkers for surveying ongoing DNA-damage related signaling in oxic and hypoxic cells during clinical radiotherapy.     

Expression of DNA mismatch repair proteins in transformed non-Hodgkin's lymphoma: relationship to smoking

It has been hypothesized that defects in DNA-mismatch repair are associated with smoking in certain types of transformed non-Hodgkin lymphoma (NHL). We have analyzed biopsy samples from two indolent B-cell lymphomas, follicular lymphoma (FL) and chronic lymphocytic leukemia/small lymphocytic leukemia (CLL/SLL), that have transformed to diffuse-large B-cell lymphoma (DLBCL). We correlated the presence or absence of DNA-mismatch repair enzymes by immunostaining as well as the p53 status to smoking history. Of all patients (n = 30), 37% showed negative immunostaining of MLH1, 16% showed negative immunostaining of MSH2 and 63% had p53 mutations and/or protein expression. Eighteen out of 20 transformed follicular lymphomas and seven out of 10 CLL/SLL that have transformed to DLBCL (Richter's syndrome) were informative for smoking histories. We found that the relative risk of negative immunostaining for either MLH1 or MSH2 was 2.2 times higher in smokers than non-smokers (relative risk = 2.2041, 95% confidence interval: 0.89714, 5.41491). No direct correlation was found between smoking and the mutations in the p53 gene. These results suggest that cigarette smoking may play a role in the development of transformed lymphomas through defective mismatch repair.     

The effect of cis-platinum on the repair of radiation damage in plateau phase Chinese hamster (V-79) cells

The interaction of cis-dichlorodiammine platinum (II) (cis-DDP) with irradiation may be important in the clinical settings for which this drug is currently used. We have approached this problem by observing the effect of cis-DDP on repair of sublethal radiation damage (SLD) and potentially lethal radiation damage (PLD).Fed plateau phase Chinese hamster (V-79) cells were pretreated with cis-DDP for 2 hours prior to irradiation and for varying intervals after irradiation in single dose and two dose repair experiments. For drug concentrations of 5 μM and 10 μM (minimally toxic doses), inhibition of repair was observed in a split dose experiment. Repair of PLD was inhibited only minimally in the presence of cis-platinum in single dose experiments. This selective drug radiation interaction suggests that simultaneous combinations of platinum with radiation may result in altered biological effects of radiation.     

甲状腺滤泡癌组织中PD-L1与dMMR相关蛋白表达的关系及其临床意义

目的:探讨甲状腺滤泡癌组织中PD-L1与dMMR相关蛋白表达的关系及其临床意义.方法:收集2015年1月至2020年6月福建医科大学附属第二医院60例甲状腺滤泡癌患者的癌组织蜡块,再次经H-E染色确诊,采用免疫组化法检测癌组织和癌旁组织中PD-Ll的表达以及MMR系统4个基因(MLH1、MSH2、MSH6、PMS2)编...     

Hypermethylation of the DNA mismatch repair gene hMLH1 and its association with lymph node metastasis and T1799A BRAF mutation in patients with papillary thyroid cancer

BACKGROUND: It remains to be investigated whether the aberrant methylation of DNA repair genes plays a pathogenic role in BRAF mutation-promoted tumorigenesis of papillary thyroid cancer (PTC). METHODS: In the current study, the promoter methylation status of 23 DNA repair genes in relation to clinicopathologic characteristics and BRAF mutation was examined in PTC tumors using methylation-specific polymerase chain reaction. RESULTS: Among the 38 PTC tumors examined, 3 of 23 DNA repair genes were hypermethylated, including the hMLH1 gene in 8 of 38 samples (21%), the PCNA gene in 5 of 38 samples (13%), and the OGG1 gene in 2 of 38 samples (5%). Methylation of these genes was also found in some thyroid cancer cell lines. Methylation of the hMLH1 gene in particular was found to be associated with lymph node metastasis of PTC (5 of 8 samples [63%] in the methylation group vs 3 of 30 samples [10%] in the nonmethylation group; P = .0049). Methylation of the hMLH1 gene was also found to be associated with the T1799A BRAF mutation in PTC (6 of 19 samples (32%) in the BRAF mutation-positive group vs 2 of 19 samples (11%) in the BRAF mutation-negative group; P = .042). CONCLUSIONS: The data from the current study suggest that, as shown previously in colon cancer, aberrant methylation of the hMLH1 gene may play a role in BRAF mutation-promoted thyroid tumorigenesis.     

Deleted in breast cancer 1 (DBC1) deficiency results in apoptosis of breast cancer cells through impaired responses to UV-induced DNA damage

DBC1 (deleted in breast cancer 1) participates in the regulation of cell survival and death in response to various stimuli. In particular, DBC1 promotes cell death upon DNA damage through inhibition of SIRT1 deacetylase. However, the SIRT1-independent functions of DBC1 in the regulation of DNA damage response are less well understood. Therefore, we analyzed the DNA damage response in Hs578T breast cancer cell line in which the DBC1–SIRT1 interaction is barely detectable. DBC1–siRNA transfected cells showed a failure in the DNA damage checkpoint and the accumulation of genomic damage following UV irradiation. In addition, DBC1-deficient cells exhibited less JNK activation. Finally, the interruptions of signaling in DBC1-depleted cells contributed to cell death in response to UV irradiation. Overall, these data suggest that DBC1 is essential for a fully efficient and effective response to UV irradiation. Therefore, DBC1 plays a critical role in maintaining genomic stability and cellular integrity following UV-induced genotoxic stress.