Validation of Next-Generation Sequencing of Entire Mitochondrial Genomes and the Diversity of Mitochondrial DNA Mutations in Oral Squamous Cell Carcinoma

Background

Oral squamous cell carcinoma (OSCC) is mainly caused by smoking and alcohol abuse and shows a five-year survival rate of ~50%. We aimed to explore the variation of somatic mitochondrial DNA (mtDNA) mutations in primary oral tumors, recurrences and metastases.

Methods

We performed an in-depth validation of mtDNA next-generation sequencing (NGS) on an Illumina HiSeq 2500 platform for its application to cancer tissues, with the goal to detect low-level heteroplasmies and to avoid artifacts. Therefore we genotyped the mitochondrial genome (16.6 kb) from 85 tissue samples (tumors, recurrences, resection edges, metastases and blood) collected from 28 prospectively recruited OSCC patients applying both Sanger sequencing and high-coverage NGS (~35,000 reads per base).

Results

We observed a strong correlation between Sanger sequencing and NGS in estimating the mixture ratio of heteroplasmies (r = 0.99; p<0.001). Non-synonymous heteroplasmic variants were enriched among cancerous tissues. The proportions of somatic and inherited variants in a given gene region were strongly correlated (r = 0.85; p<0.001). Half of the patients shared mutations between benign and cancerous tissue samples. Low level heteroplasmies (<10%) were more frequent in benign samples compared to tumor samples, where heteroplasmies >10% were predominant. Four out of six patients who developed a local tumor recurrence showed mutations in the recurrence that had also been observed in the primary tumor. Three out of five patients, who had tumor metastases in the lymph nodes of their necks, shared mtDNA mutations between primary tumors and lymph node metastases. The percentage of mutation heteroplasmy increased from the primary tumor to lymph node metastases.

Conclusions

We conclude that Sanger sequencing is valid for heteroplasmy quantification for heteroplasmies ≥10% and that NGS is capable of reliably detecting and quantifying heteroplasmies down to the 1%-level. The finding of shared mutations between primary tumors, recurrences and metastasis indicates a clonal origin of malignant cells in oral cancer.     

Somatic mutations in mitochondrial genome and their potential roles in the progression of human gastric cancer

Background

Somatic mutation in mitochondrial DNA (mtDNA) has been proposed to contribute to initiation and progression of human cancer. In our previous study, high frequency of somatic mutations was found in the D-loop region of mtDNA of gastric cancers. However, it is unclear whether somatic mutations occur in the coding region of mtDNA of gastric cancers.

Methods

Using DNA sequencing, we studied 31 gastric cancer specimens and corresponding non-cancerous stomach tissues. Moreover, a human gastric cancer SC-M1 cell line was treated with oligomycin to induce mitochondrial dysfunction. Cisplatin sensitivity and cell migration were analyzed.

Results

We identified eight somatic mutations in the coding region of mtDNAs of seven gastric cancer samples (7/31, 22.6%). Patients with somatic mutations in the entire mtDNA of gastric cancers did not show significant association with their clinicopathologic features. Among the eight somatic mutations, five point mutations (G3697A, G4996A, G9986A, C12405T and T13015C) are homoplasmic and three mutations (5895delC, 7472insC and 12418insA) are heteroplasmic. Four (4/8, 50%) of these somatic mutations result in amino acid substitutions in the highly conserved regions of mtDNA, which potentially lead to mitochondrial dysfunction. In addition, in vitro experiments in SC-M1 cells revealed that oligomycin-induced mitochondrial dysfunction promoted resistance to cisplatin and enhanced cell migration. N-acetyl cysteine was effective in the prevention of the oligomycin-enhanced migration, which suggests that reactive oxygen species generated by defective mitochondria may be involved in the enhanced migration of SC-M1 cells.

General Significance

Our results suggest that somatic mtDNA mutations and mitochondrial dysfunction may play an important role in the malignant progression of gastric cancer.     

A20 Mutation Is Not a Prognostic Marker for Activated B-Cell-Like Diffuse Large B-Cell Lymphoma

Background

Constitutive activation of nuclear factor κB (NF-κB) is a hallmark of activated B-cell-like diffuse large B-cell lymphoma (ABC-DLBCL). Mutations in the A20 gene activate NF-κB, but the prognostic value of A20 mutations in ABC-DLBLC is unclear.

Purpose

To investigate the prognostic value of A20 mutation in ABC-DLBCL patients.

Methods

The somatic mutation of A20 was investigated in 68 de novo ABC-DLBCLs by PCR/sequencing. The Kaplan-Meier method was used to estimate median overall survival (OS) and progression-free survival (PFS).

Results

The A20 mutation rate in ABC-DLBCL patients was 29.4%. Complete remission rates were 35% and 45.8% in patients with and without A20 mutations, respectively (P = 0.410). In patients with and without A20 mutations, the median OS was 24.0 and 30.6 months, respectively (P = 0.58), and the median PFS was 15 and 17.4 months, respectively (P = 0.52). None of the differences between the patient groups were significant.

Conclusions

Our findings suggested that the A20 mutation is a frequent event in ABC-DLBCLs. However, there was no significant difference in PFS and OS in patients with or without A20 mutations. Further study is required to completely exclude A20 somatic mutation as a prognostic marker in the ABC subtype of DLBLC.     

Genetics of Aldosterone-Producing Adenoma in Korean Patients

Objectives

Recently, somatic mutations in KCNJ5, ATP1A1, ATP2B3, and CACNA1D genes were found to be associated with the pathogenesis of aldosterone-producing adenoma (APA). This study aimed to investigate the prevalence of somatic mutations in KCNJ5, ATP1A1, ATP2B3, and CACNA1D and examine the correlations between these mutations and the clinical and biochemical characteristics in Korean patients with APA.

Methods

We performed targeted gene sequencing in 66 patients with APA to detect somatic mutations in these genes.

Results

Somatic KCNJ5 mutations were found in 47 (71.2%) of the 66 patients with APA (31 cases of p.G151R and 16 cases of p.L168R); these two mutations were mutually exclusive. Somatic mutations in the ATP1A1, ATP2B3, and CACNA1D genes were not observed. Somatic KCNJ5 mutations were more prevalent in female patients (66% versus 36.8%, respectively; P = 0.030). Moreover, patients with KCNJ5 mutations comprised a significantly higher proportion of patients younger than 35 years of age (19.1% versus 0%, respectively; P = 0.040). There were no significant differences in pre-operative blood pressure, plasma aldosterone, serum potassium, lateralization index, and adenoma size according to mutational status. Patients with KCNJ5 mutations were less likely to need antihypertensive medications after adrenalectomy compared with those without mutation (36.2% versus 63.2%; P = 0.045).

Conclusions

The present study demonstrated the high prevalence of somatic KCNJ5 mutations in Korean patients with APA. Carriers of somatic KCNJ5 mutations were more likely to be female. Early diagnosis and better therapeutic outcomes were associated with somatic KCNJ5 mutations in APA.     

Detection of epidermal growth factor receptor mutations in formalin fixed paraffin embedded biopsies in Malaysian non-small cell lung cancer patients

Background

Somatic mutations of the epidermal growth factor receptor (EGFR) are reportedly associated with various responses in non-small cell lung cancer (NSCLC) patients receiving the anti-EGFR agents. Detection of the mutation therefore plays an important role in therapeutic decision making. The aim of this study was to detect EGFR mutations in formalin fixed paraffin embedded (FFPE) samples using both Scorpion ARMS and high resolution melt (HRM) assay, and to compare the sensitivity of these methods.

Results

All of the mutations were found in adenocarcinoma, except one that was in squamous cell carcinoma. The mutation rate was 45.7% (221/484). Complex mutations were also observed, wherein 8 tumours carried 2 mutations and 1 tumour carried 3 mutations.

Conclusions

Both methods detected EGFR mutations in FFPE samples. HRM assays gave more EGFR positive results compared to Scorpion ARMS.     

Prospective Evaluation of First-Line Erlotinib in Advanced Non-Small Cell Lung Cancer (NSCLC) Carrying an Activating EGFR Mutation: A Multicenter Academic Phase II Study in Caucasian Patients (FIELT)

Introduction

Epidermal Growth Factor Receptor (EGFR) tyrosine kinase inhibition is the preferred first-line treatment of advanced adenocarcinoma of the lung that harbors EGFR activating tyrosine kinase domain mutations. Most data available pertain to Asian populations in which such mutations are more prevalent. We report on the long-term results of first-line treatment with erlotinib in Caucasian patients with advanced adenocarcinoma of the lung that have a somatic EGFR mutation in their tumor.

Methods

Multicenter academic prospective phase II study with erlotinib in patients with an activating EGFR tyrosine kinase (TK) domain somatic mutation (any exon encoding the kinase domain) in the tumor and no prior treatment for their advanced disease.

Results

Phenotypic preselecting of 229 patients led to a high EGFR mutation detection rate of 24% of which 46 patients were included in the phase II study. With a progression free survival (PFS) of 81% at three months the study met its primary endpoint for presumed superiority over chemotherapy. With an overall median PFS of 11 months and a median overall survival (OS) of 23 months, the results compare favorably with results obtained in randomized studies using TKI in first line in EGFR mutation positive adenocarcinoma of the lung.

Conclusion

The present study reinforces the use of EGFR tyrosine kinase inhibition (TKI) as a first line treatment of choice for advanced adenocarcinoma of the lung carrying an activating EGFR mutation. The mutation rate in preselected Caucasian patients is higher than previously reported. Issues relevant for clinical practice are discussed.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00339586","term_id":"NCT00339586"}}NCT00339586     

Cathepsin B Expression and the Correlation with Clinical Aspects of Oral Squamous Cell Carcinoma

Background

Cathepsin B (CTSB), a member of the cathepsin family, is a cysteine protease that is widely distributed in the lysosomes of cells in various tissues. It is overexpressed in several human cancers and may be related to tumorigenesis. The main purpose of this study was to analyze CTSB expression in oral squamous cell carcinoma (OSCC) and its correlation with patient prognosis.

Methodology/Principal Findings

Tissue microarrays were used to detect CTSB expression in 280 patients and to examine the association between CTSB expression and clinicopathological parameters. In addition, the metastatic effects of the CTSB knockdown on two oral cancer cell lines were investigated by transwell migration assay. Cytoplasmic CTSB expression was detected in 34.6% (97/280) of patients. CTSB expression was correlated with positive lymph node metastasis (p = 0.007) and higher tumor grade (p = 0.008) but not with tumor size and distant metastasis. In addition, multivariate analysis using a Cox proportional hazards model revealed a higher hazard ratio, demonstrating that CTSB expression was an independent unfavorable prognostic factor in buccal mucosa carcinoma patients. Furthermore, the Kaplan–Meier curve revealed that buccal mucosa OSCC patients with positive CTSB expression had significantly shorter overall survival. Moreover, treatment with the CTSB siRNA exerted an inhibitory effect on migration in OC2 and CAL27 oral cancer cells.

Conclusions

We conclude that CTSB expression may be useful for determining OSCC prognosis, particularly for patients with lymph node metastasis, and may function as a biomarker of the survival of OSCC patients in Taiwan.     

AZD2014 Radiosensitizes Oral Squamous Cell Carcinoma by Inhibiting AKT/mTOR Axis and Inducing G1/G2/M Cell Cycle Arrest

Background

Oral squamous cell carcinoma (OSCC) is one of the most common malignant neoplasms in Taiwan. Activation of the mTOR signaling pathway has been linked to decreased radiation responsiveness in human oral cancer, thus it limits efficacy of radiotherapy. To address this question, we investigated the effect of AZD2014, a novel small molecular ATP-competitive inhibitor of mTORC1 and mTORC2 kinase, as a radiosensitizer in primary OSCC and OSCC-derived cell line models.

Methods

We isolated primary tumor cells from OSCC tissues and cell lines. AZD2014 was administered with and without ionizing radiation. The radiosensitizing effect of AZD2014 were then assessed using cell viability assays, clonogenic survival assays, and cell cycle analyses. Western blotting was used to detect protein expression.

Results

Combination treatment with AZD2014 and irradiation resulted in significant reduction in OSCC cell line and primary OSCC cell colony formation due to the enhanced inhibition of AKT and both mTORC1 and mTORC2 activity. Pre-treatment with AZD2014 in irradiated oral cancer cells induced tumor cell cycle arrest at the G1 and G2/M phases, which led to disruption of cyclin D1-CDK4 and cyclin B1-CDC2 complexes. Moreover, AZD2014 synergized with radiation to promote both apoptosis and autophagy by increasing caspase-3 and LC3 in primary OSCC cells.

Conclusions

These findings suggest that in irradiated OSCC cells, co-treatment with AZD2014, which targets mTORC1 and mTORC2 blockade, is an effective radiosensitizing strategy for oral squamous cell carcinoma.     

口腔鳞状细胞癌线粒体DNA的HVRⅢ区突变的研究（英文）

目的：检测口腔鳞状细胞癌患者线粒体DNA复制控制区（mtDNA D-loop）高变Ⅲ区（hypervariable regionⅢ,HVRⅢ）的突变情况,并探讨其意义。方法：以口腔鳞状细胞癌患者癌旁组织及正常组织作为对照,对7例口腔鳞状细胞癌组织样本的mtDNA D-loop HVRⅢ区进行PCR扩增和测序分析。结果：在7例患者的癌组织、癌旁组织、正常组织样本中共发现72个（56种）核苷酸改变,其中51个（26种）为核苷酸多态性改变;3个肿瘤组织样本中共发现21个突变,其中16个位于HVRⅢ区范围内;癌旁组织及正常组织未发现突变;口腔鳞状细胞癌的mtDNA D-loop HVRⅢ区突变率为42.9%（3/7）。结论：mtDNA D-loop HVRⅢ区的变异可能与口腔鳞状细胞癌的易感性有一定的联系;本研究为寻找新的肿瘤基因诊断和肿瘤遗传易感性的标志物提供了依据。     

High-Throughput Genotyping in Metastatic Esophageal Squamous Cell Carcinoma Identifies Phosphoinositide-3-Kinase and BRAF Mutations

Background

Given the high incidence of metastatic esophageal squamous cell carcinoma, especially in Asia, we screened for the presence of somatic mutations using OncoMap platform with the aim of defining subsets of patients who may be potential candidate for targeted therapy.

Methods and Materials

We analyzed 87 tissue specimens obtained from 80 patients who were pathologically confirmed with esophageal squamous cell carcinoma and received 5-fluoropyrimidine/platinum-based chemotherapy. OncoMap 4.0, a mass-spectrometry based assay, was used to interrogate 471 oncogenic mutations in 41 commonly mutated genes. Tumor specimens were prepared from primary cancer sites in 70 patients and from metastatic sites in 17 patients. In order to test the concordance between primary and metastatic sites from the patient for mutations, we analyzed 7 paired (primary-metastatic) specimens. All specimens were formalin-fixed paraffin embedded tissues and tumor content was >70%.

Results

In total, we have detected 20 hotspot mutations out of 80 patients screened. The most frequent mutation was PIK3CA mutation (four E545K, five H1047R and one H1047L) (N = 10, 11.5%) followed by MLH1 V384D (N = 7, 8.0%), TP53 (R306, R175H and R273C) (N = 3, 3.5%), BRAF V600E (N = 1, 1.2%), CTNNB1 D32N (N = 1, 1.2%), and EGFR P733L (N = 1, 1.2%). Distributions of somatic mutations were not different according to anatomic sites of esophageal cancer (cervical/upper, mid, lower). In addition, there was no difference in frequency of mutations between primary-metastasis paired samples.

Conclusions

Our study led to the detection of potentially druggable mutations in esophageal SCC which may guide novel therapies in small subsets of esophageal cancer patients.     

Comprehensive Re-Sequencing of Adrenal Aldosterone Producing Lesions Reveal Three Somatic Mutations near the KCNJ5 Potassium Channel Selectivity Filter

Background

Aldosterone producing lesions are a common cause of hypertension, but genetic alterations for tumorigenesis have been unclear. Recently, either of two recurrent somatic missense mutations (G151R or L168R) was found in the potassium channel KCNJ5 gene in aldosterone producing adenomas. These mutations alter the channel selectivity filter and result in Na⁺ conductance and cell depolarization, stimulating aldosterone production and cell proliferation. Because a similar mutation occurs in a Mendelian form of primary aldosteronism, these mutations appear to be sufficient for cell proliferation and aldosterone production. The prevalence and spectrum of KCNJ5 mutations in different entities of adrenocortical lesions remain to be defined.

Materials and Methods

The coding region and flanking intronic segments of KCNJ5 were subjected to Sanger DNA sequencing in 351 aldosterone producing lesions, from patients with primary aldosteronism and 130 other adrenocortical lesions. The specimens had been collected from 10 different worldwide referral centers.

Results

G151R or L168R somatic mutations were identified in 47% of aldosterone producing adenomas, each with similar frequency. A previously unreported somatic mutation near the selectivity filter, E145Q, was observed twice. Somatic G151R or L168R mutations were also found in 40% of aldosterone producing adenomas associated with marked hyperplasia, but not in specimens with merely unilateral hyperplasia. Mutations were absent in 130 non-aldosterone secreting lesions. KCNJ5 mutations were overrepresented in aldosterone producing adenomas from female compared to male patients (63 vs. 24%). Males with KCNJ5 mutations were significantly younger than those without (45 vs. 54, respectively; p<0.005) and their APAs with KCNJ5 mutations were larger than those without (27.1 mm vs. 17.1 mm; p<0.005).

Discussion

Either of two somatic KCNJ5 mutations are highly prevalent and specific for aldosterone producing lesions. These findings provide new insight into the pathogenesis of primary aldosteronism.     

Novel Somatic Mutations to PI3K Pathway Genes in Metastatic Melanoma

Background

BRAF^V600 inhibitors have offered a new gateway for better treatment of metastatic melanoma. However, the overall efficacy of BRAF^V600 inhibitors has been lower than expected in clinical trials, and many patients have shown resistance to the drug’s effect. We hypothesized that somatic mutations in the Phosphoinositide 3-Kinase (PI3K) pathway, which promotes proliferation and survival, may coincide with BRAF^V600 mutations and contribute to chemotherapeutic resistance.

Methods

We performed a somatic mutation profiling study using the 454 FLX pyrosequencing platform in order to identify candidate cancer genes within the MAPK and PI3K pathways of melanoma patients. Somatic mutations of theses candidate cancer genes were then confirmed using Sanger sequencing.

Results

As expected, BRAF^V600 mutations were seen in 51% of the melanomas, whereas NRAS mutations were seen in 19% of the melanomas. However, PI3K pathway mutations, though more heterogeneous, were present in 41% of the melanoma, with PTEN being the highest mutated PI3K gene in melanomas (22%). Interestingly, several novel PI3K pathway mutations were discovered in MTOR, IRS4, PIK3R1, PIK3R4, PIK3R5, and NFKB1. PI3K pathway mutations co-occurred with BRAF^V600 mutations in 17% of the tumors and co-occurred with 9% of NRAS mutant tumors, implying cooperativity between these pathways in terms of melanoma progression.

Conclusions

These novel PI3K pathway somatic mutations could provide alternative survival and proliferative pathways for metastatic melanoma cells. They therefore may be potential chemotherapeutic targets for melanoma patients who exhibit resistance to BRAF^V600 inhibitors.     

Prognostic Value Analysis of Mutational and Clinicopathological Factors in Non-Small Cell Lung Cancer

Introduction

Targeting activating oncogenic driver mutations in lung adenocarcinoma has led to prolonged survival in patients harboring these specific genetic alterations. The prognostic value of these mutations has not yet been elucidated. The prevalence of recently uncovered non-coding somatic mutation in promoter region of TERT gene is also to be validated in lung cancer. The purpose of this study is to show the prevalence, association with clinicalpathological features and prognostic value of these factors.

Methods

In a cohort of patients with non-small cell lung cancer (NSCLC) (n = 174, including 107 lung adenocarcinoma and 67 lung squamous cell carcinoma), EGFR, KRAS, HER2 and BRAF were directly sequenced in lung adeoncarcinoma, ALK fusions were screened using FISH (Fluorescence in situ Hybridization).TERT promoter region was sequenced in all of the 174 NSCLC samples. Associations of these somatic mutations and clinicopathological features, as well as prognostic factors were evaluated.

Results

EGFR, KRAS, HER2, BRAF mutation and ALK fusion were mutated in 25.2%, 6.5%, 1.9%, 0.9% and 3.7% of lung adenocarcinomas. No TERT promoter mutation was validated by reverse-sided sequencing. Lung adenocarcinoma with EGFR and KRAS mutations showed no significant difference in Disease-free Survival (DFS) and Overall Survival (OS). Cox Multi-variate analysis revealed that only N stage and HER2 mutation were independent predictors of worse overall survival (HR = 1.653, 95% CI 1.219–2.241, P = 0.001; HR = 12.344, 95% CI 2.615–58.275, P = 0.002).

Conclusions

We have further confirmed that TERT promoter mutation may only exist in a very small fraction of NSCLCs. These results indicate that dividing lung adenocarcinoma into molecular subtypes according to oncogenic driver mutations doesn''t predict survival difference of the disease.     

The Response,Outcome and Toxicity of Aggressive Palliative Thoracic Radiotherapy for Metastatic Non-Small Cell Lung Cancer Patients with Controlled Extrathoracic Diseases

Background and Purpose

For metastatic non-small cell lung cancer (NSCLC) patients with controlled extrathoracic disease after systemic treatment, stable or progressive primary lung lesions may cause respiratory symptoms and increase comorbidities. In the present study, we sought to investigate whether aggressive palliative thoracic radiotherapy (RT) can enhance local control and improve the survival for this subgroup of patients.

Materials and Methods

Between March 2006 and December 2014, 56 patients with metastatic NSCLC who had responsive or stable extrathoracic diseases after chemotherapy and/or molecular targets, and received thoracic RT for stable and progressive primary lung lesions were included. RT with a median dose of 55 Gy (range, 40–62 Gy) was administered in 1.8–2.5 Gy fractions to primary lung tumor and regional mediastinal lymph nodes using modern RT technique. Overall survival (OS) from diagnosis, and locoregional progression-free survival (LRPFS), and survival calculated from radiotherapy (OS-RT) were estimated using the Kaplan-Meier method.

Results

There were 37 men and 19 women with a median age of 60 years at diagnosis. The median interval from the diagnosis of metastatic disease to thoracic RT was 8 months. Following thoracic RT, 26 patients (46%) achieved complete or partial response (overall response rate, ORR). Patients with squamous cell carcinoma or poorly-differentiated carcinoma had a higher ORR than those with adenocarcinoma (63% vs. 34%, P = 0.034). EGFR mutations was closely associated with a better ORR (45% vs. 29%, P = 0.284). At a median follow-up time of 44 months, the median OS, LRPFS after RT, and OS-RT were 50 months, 15 months, and 18 months.

Conclusion

Radical palliative throractic RT is safe and might be beneficial for primary lung lesions of metastatic NSCLC patients with controlled extrathoracic diseases.     

Clinical Outcomes of Patients with Resected Oral Cavity Cancer and Simultaneous Second Primary Malignancies

Objectives

Simultaneous second primary tumors (SSPT) are not uncommon in patients with oral cavity squamous cell carcinoma (OSCC) living in areas where the habit of betel quid chewing is widespread. We sought to identify the main prognostic factors in OSCC patients with SSPT and incorporate them into a risk stratification scheme.

Methods

A total of 1822 consecutive patients with primary OSCC treated between January 1996 and February 2014 were analyzed for the presence of SSPT. The 18-month and 5-year overall survival (OS) rates served as the main outcome measures.

Results

Of the 1822 patients, 77 (4%) were found to have SSPT (i.e, two malignancies identified within one month of each other). The 18-month and 5-year OS rates in patients without SSPT and with SSPT were 82% and 69%, and 72% and 53%, respectively (p = 0.0063). Patients with SSPT were further divided into patients with either esophageal cancer or hepatocellular carcinoma (eso-HCC subgroup, n = 8) and other tumors (NO eso-HCC subgroup, n = 69). After multivariate analysis, neck nodal extracapsular spread (ECS, n = 18) and the presence of eso-HCC were identified as independent adverse prognostic factors. The 18-month OS rates of SSPT patients with both eso-HCC and ECS (n = 5) vs. the remaining patients (n = 72) were 0% and 78%, respectively (p < 0.0001).

Conclusion

OSCC patients with neck nodal ECS and esophageal cancer or hepatocellular carcinoma as SSPT have a dismal short-term prognosis.     

Somatic mutations in the D-loop and decrease in the copy number of mitochondrial DNA in human hepatocellular carcinoma

Somatic mutations in mitochondrial DNA (mtDNA) have been detected in many human cancers, including hepatocellular carcinoma (HCC). The D-loop region was found to be a "hot spot" for mutation in mtDNA of the tumors. However, effects of the D-loop mutations on the copy number of mtDNA in tumor tissues are poorly understood. Using direct sequencing, we examined mutations in the D-loop region of mtDNA in 61 HCCs and the corresponding non-tumor liver tissues. The results revealed that 39.3% of the HCCs carried somatic mutation(s) in the D-loop of mtDNA, and most of these mutations were homoplasmic. Moreover, 37.0% (10/27) of these mutations were T-to-C and G-to-A transitions and 40.7% (11/27) of them were located in the polycytidine stretch between nucleotide position (np) 303 and 309 of mtDNA. In addition, we found that mtDNA copy number of HCC was significantly decreased in 60.5% of the patients with hepatoma, especially in those with somatic mutation(s) in the D-loop of mtDNA (17/24). This decrease in mtDNA copy number was highly associated with the occurrence of point mutations near the replication origin of the heavy-strand of mtDNA. Interestingly, we found that 42.9% (6/14) of the HCCs without mutation in the D-loop had a reduced copy number of mtDNA, indicating that other unidentified factors involved in mitochondrial biogenesis might be defective in the tumor. The results obtained in this study strongly suggest that somatic mutations in the D-loop together with the decrease in the copy number of mtDNA may be an important event during the early phase of liver carcinogenesis.     

Clinicopathological Characteristics and Survival Outcomes of Primary Signet Ring Cell Carcinoma in the Stomach: Retrospective Analysis of Single Center Database

Purpose

To investigate the clinicopathological features and prognosis of signet ring cell carcinoma of the stomach (SRC).

Methods

A total of 1464 gastric cancer patients who underwent curative gastrectomy from 2000 to 2008 at a single center were evaluated. Signet ring cell carcinoma (SRC) was defined as the presence of at least 50% signet ring cells in the pathologic specimen. The clinicopathological parameters and prognosis of SRC were analyzed by comparing with non-signet ring cell carcinoma (NSRC).

Results

Of 1464 patients, 138 patients (9.4%) were classified as SRC. There were significant differences in gender, age, tumor location, TNM stage, p21 expression, and p53 expression between SRC and NSRC. The 5-year survival rates of SRC and NSRC were 36.2% and 49.5%, respectively. The prognosis of SRC was poorer than that of NSRC (P <0.001). Multivariate analysis showed that SRC histology was an independent factor for poor prognosis (P <0.001).

Conclusion

Patients with SRC tend to present with a more advanced stage and poorer prognosis than patients with other types of gastric carcinoma.     

Analysis of Tp53 codon 72 polymorphisms, Tp53 mutations, and HPV infection in cutaneous squamous cell carcinomas

Background

Non-melanoma skin cancers are one of the most common human malignancies accounting for 2–3% of tumors in the US and represent a significant health burden. Epidemiology studies have implicated Tp53 mutations triggered by UV exposure, and human papilloma virus (HPV) infection to be significant causes of non-melanoma skin cancer. However, the relationship between Tp53 and cutaneous HPV infection is not well understood in skin cancers. In this study we assessed the association of HPV infection and Tp53 polymorphisms and mutations in lesional specimens with squamous cell carcinomas.

Methods

We studied 55 cases of histologically confirmed cutaneous squamous cell carcinoma and 41 controls for the presence of HPV infection and Tp53 genotype (mutations and polymorphism).

Results

We found an increased number of Tp53 mutations in the squamous cell carcinoma samples compared with perilesional or control samples. There was increased frequency of homozygous Tp53-72R polymorphism in cases with squamous cell carcinomas, while the Tp53-72P allele (Tp53-72R/P and Tp53-72P/P) was more frequent in normal control samples. Carcinoma samples positive for HPV showed a decreased frequency of Tp53 mutations compared to those without HPV infection. In addition, carcinoma samples with a Tp53-72P allele showed an increased incidence of Tp53 mutations in comparison carcinomas samples homozygous for Tp53-72R.

Conclusions

These studies suggest there are two separate pathways (HPV infection and Tp53 mutation) leading to cutaneous squamous cell carcinomas stratified by the Tp53 codon-72 polymorphism. The presence of a Tp53-72P allele is protective against cutaneous squamous cell carcinoma, and carcinoma specimens with Tp53-72P are more likely to have Tp53 mutations. In contrast Tp53-72R is a significant risk factor for cutaneous squamous cell carcinoma and is frequently associated with HPV infection instead of Tp53 mutations. Heterozygosity for Tp53-72R/P is protective against squamous cell carcinomas, possibly reflecting a requirement for both HPV infection and Tp53 mutations.