Forward and reverse mutations in stages of cancer development.

BACKGROUND: Massive occurrences of interstitial loss of heterozygosity (LOH) likely resulting from gene conversions were found by us in different cancers as a type of single-nucleotide variations (SNVs), comparable in abundance to the commonly investigated gain of heterozygosity (GOH) type of SNVs, raising the question of the relationships between these two opposing types of cancer mutations. METHODS: In the present study, SNVs in 12 tetra sample and 17 trio sample sets from four cancer types along with copy number variations (CNVs) were analyzed by AluScan sequencing, comparing tumor with white blood cells as well as tissues vicinal to the tumor. Four published "nontumor"-tumor metastasis trios and 246 pan-cancer pairs analyzed by whole-genome sequencing (WGS) and 67 trios by whole-exome sequencing (WES) were also examined. RESULTS: Widespread GOHs enriched with CG-to-TG changes and associated with nearby CNVs and LOHs enriched with TG-to-CG changes were observed. Occurrences of GOH were 1.9-fold higher than LOH in "nontumor" tissues more than 2 cm away from the tumors, and a majority of these GOHs and LOHs were reversed in "paratumor" tissues within 2 cm of the tumors, forming forward-reverse mutation cycles where the revertant LOHs displayed strong lineage effects that pointed to a sequential instead of parallel development from "nontumor" to "paratumor" and onto tumor cells, which was also supported by the relative frequencies of 26 distinct classes of CNVs between these three types of cell populations. CONCLUSIONS: These findings suggest that developing cancer cells undergo sequential changes that enable the "nontumor" cells to acquire a wide range of forward mutations including ones that are essential for oncogenicity, followed by revertant mutations in the "paratumor" cells to avoid growth retardation by excessive mutation load. Such utilization of forward-reverse mutation cycles as an adaptive mechanism was also observed in cultured HeLa cells upon successive replatings. An understanding of forward-reverse mutation cycles in cancer development could provide a genomic basis for improved early diagnosis, staging, and treatment of cancers.

Waterborne exposure to BPS causes thyroid endocrine disruption in zebrafish larvae.

Bisphenol S (BPS) is widely used as a raw material in industry, resulting in its ubiquitous distribution in natural environment, including the aqueous environment. However, the effect of BPS on the thyroid endocrine system is largely unknown. In this study, zebrafish (Danio rerio) embryos were exposed to BPS at 1, 3, 10, and 30 µg/L, from 2 h post-fertilization (hpf) to 168hpf. Bioconcentration of BPS and whole-body thyroid hormones (THs), thyroid-stimulating hormone (TSH) concentrations as well as transcriptional profiling of key genes related to the hypothalamic-pituitary-thyroid (HPT) axis were examined. Chemical analysis indicated that BPS was accumulated in zebrafish larvae. Thyroxine (T4) and triiodothyronine (T3) levels were significantly decreased at ≥ 10 and 30 µg/L of BPS, respectively. However, TSH concentration was significantly induced in the 10 and 30 µg/L BPS-treated groups. After exposure to BPS, the mRNA expression of corticotrophin releasing hormone (crh) and thyroglobulin (tg) genes were up-regulated at ≥10 µg/L of BPS, in a dose-response manner. The transcription of genes involved in thyroid development (pax8) and synthesis (sodium/iodide symporter, slc5a5) were also significantly increased in the 30 µg/L of BPS treatment group. Moreover, exposure to 10 µg/L or higher concentration of BPS significantly up-regulated genes related to thyroid hormone metabolism (deiodinases, dio1, dio2 and uridinediphosphate glucoronosyltransferases, ugt1ab), which might be responsible for the altered THs levels. However, the transcript of transthyretin (ttr) was significantly down-regulated at ≥ 3 µg/L of BPS, while the mRNA levels of thyroid hormone receptors (trα and trß) and dio3 remained unchanged. All the results indicated that exposure to BPS altered the whole-body THs and TSH concentrations and changed the expression profiling of key genes related to HPT axis, thus triggering thyroid endocrine disruption.

The clinicopathological significance of RUNX3 hypermethylation and mRNA expression in human breast cancer, a meta-analysis.

Aberrant promoter methylation of RUNX3 has been reported in several tumors including human breast cancer (BC). However, the association between RUNX3 hypermethylation and incidence of BC remains elusive. In this study, a detailed literature search was performed in Medline and Google Scholar for related research publications. Analysis of pooled data were executed. Odds ratios with corresponding confidence intervals were determined and summarized, respectively. Finally, 13 studies were identified for the meta-analysis. Analysis of the pooled data showed that RUNX3 hypermethylation was significantly higher in both ductal carcinoma in situ and invasive ductal carcinoma (IDC) than in normal breast tissues. In addition, RUNX3 methylation was significantly higher in IDC than in benign tumor. However, RUNX3 methylation was not significantly higher in IDC than in ductal carcinoma in situ. We also determined that RUNX3 hypermethylation was significantly higher in ER positive BC than in ER negative BC. In addition, high RUNX3 mRNA expression was found to be correlated with better overall survival and relapse-free survival for all BC patients. Our results strongly support that RUNX3 hypermethylation may play an important role in BC incidence. RUNX3 methylation is a valuable early biomarker for the diagnosis of BC. Further large-scale studies will provide more insight into the role of RUNX3 hypermethylation in the carcinogenesis and clinical diagnosis of BC patients.

Overexpression of Thy1 and ITGA6 is associated with invasion, metastasis and poor prognosis in human gallbladder carcinoma.

Gallbladder cancer (GBC) is a rare but highly aggressive cancer for which no well-accepted prognostic biomarkers have been identified. Thymus cell antigen 1 (Thy1), also known as cluster of differentiation (CD)90, and integrin α6 (ITGA6), also known as CD49f, are important molecules in cancer and putative markers of various stem cell types. However, their role in GBC remains to be elucidated. In the present study, Thy1 and ITGA6 expression status in clinical GBC samples, which comprised squamous cell/adenosquamous carcinoma (SC/ASC) and adenocarcinoma (AC) subtypes, was investigated. The associations between Thy1 and ITGA6 expression and clinical parameters and survival rate were analyzed separately. The THY1 and ITGA6 messenger RNA levels were significantly higher in both SC/ASC and AC tissues than in adjacent non-tumor tissues (all P<0.001). These results were subsequently confirmed by immunohistochemical analyses. Overexpression of Thy1 and ITGA6 was correlated with poor differentiation, large tumor size, lymph node metastasis and great invasiveness in SC/ASC (Thy1, P=0.045, P=0.005, P=0.003 and P=0.009, respectively, and ITGA6, P=0.029, P=0.011, P=0.009 and P=0.004, respectively) and AC (Thy1, P=0.027, P<0.001, P=0.003 and P 0.004, respectively, and ITGA6, P=0.002, P=0.003, P=0.006 and P=0.006, respectively). Both Thy1 and ITGA6 were expressed at higher levels in AC with advanced tumor-node-metastasis stage (TNM) than in AC with low TNM stage (P=0.001 and P=0.018, respectively). In addition, patients with elevated Thy1 or ITGA6 expression had shorter overall survival than those with negative Thy1 or ITGA6 expression. Multivariate Cox regression analysis demonstrated that Thy1 (SC/ASC, P=0.001 and AC, P=0.005) and ITGA6 (both P=0.003) were independent predictors of poor prognosis in both SC/ASC and AC patients. In conclusion, Thy1 and ITGA6 could be clinical prognostic markers for GBC.

X-ray repair cross-complementing group 1(XRCC1) genetic polymorphisms and thyroid carcinoma risk: a meta-analysis.

A number of studies have been conducted to explore the association of XRCC1 polymorphisms with thyroid cancer risk, but the results have been inconsistent. Thus we performed the present meta-analysis to clarify this issue based on all of the evidence available to date. Relevant studies were retrieved by searching PubMed and statistical analysis conducted using Stata software. Nine studies were included in this meta-analysis (1,620 cases and 3,557 controls). There were 6 studies (932 cases and 2,270 controls) of the Arg194Trp polymorphism, 7 studies (1432 cases and 3356 controls) of the Arg280His polymorphism and 9 studies (1,620 cases and 3,557 controls) for the Arg399Gln polymorphism. No association of XRCC1 Arg194Trp, Arg280His and Arg399Gln polymorphism with thyroid cancer risk was observed in the overall analysis. However, subgroup analysis revealed: 1) an elevated risk in aa vs AA analysis (OR=2.03, 95%CI= 1.24-3.31) and recessive genetic model analysis (OR=1.93, 95%CI= 1.20-3.08) in the larger sample size trials for XRCC1 Arg194Trp polymorphism; 2) a decreased thyroid cancer risk on subgroup analysis based on ethnicity in Aa vs AA analysis (OR=0.84, 95%CI= 0.72-0.98) and in a dominant genetic model (OR=0.84, 95%CI= 0.72-0.97) in Caucasian populations for the XRCC1 Arg399Gln polymorphism; 3) a decreased thyroid cancer risk on subgroup analysis based on design type in Aa vs AA analysis (OR=0.72, 95% CI= 0.54-0.97) among the PCC trials for the Arg399Gln polymorphism. Our results suggest that the XRCC1 Arg399Gln polymorphism may be associated with decreased thyroid cancer risk among Caucasians and XRCC1 Arg194Trp may be associated with a tendency for increased thyroid cancer risk in the two larger sample size trials.

Role of potassium channels in regulation of rat coronary arteriole tone.

Activity of potassium (K(+)) channels plays a key role in regulating arterial tone and therefore blood flow. But little is known about the roles of K(+) channels in the coronary arterioles. The aim of the present study was to investigate the influences of several potassium channel blockers on resting vascular tone in isolated rat coronary arteriole. The coronary arterioles were carefully dissected, cannulated and pressurized. The inner diameter of vessels was recorded by a computerized diameter tracking system and the effects of K(+) channels on the development of vascular myogenic tone was tested by application of various K(+) channel inhibitors. Inhibition of voltage-dependent K(+) (K(V)) channels and inward rectifier K(+) (K(ir)) channels significantly increased the tone constriction. But inhibition of Ca(2+)-activated K(+) (K(Ca)) channels and ATP-sensitive K(+) (K(ATP)) channels had no effect on the resting tone. In addition, inhibition of nitric oxide synthase (NOS) further decreased the tone diameter. Combined inhibition of K(V), K(ir) and NOS induced the strongest tone constriction. Our results suggested that activity of K(V) and K(ir) channels, and basal nitric oxide (NO) contribute to the myogenic tone in rat coronary arteriole under resting conditions, but basal NO may not contribute to the activation of K(V) and K(ir) channels. K(Ca) and K(ATP) channels are likely to have a very low open probability under normal conditions.

Tanshinone II(A) elicited vasodilation in rat coronary arteriole: roles of nitric oxide and potassium channels.

Salvia miltiorrhiza has been widely used in the treatment of various cardiovascular diseases due to its ability to improve coronary microcirculation and increase coronary blood flow. Tanshinone II(A), the major active lipophilic ingredient responsible for the beneficial actions of Salvia miltiorrhiza, was shown to induce vasodilation in coronary arteries. But its effects on coronary arterioles remain unknown. The purpose of this study was to investigate the effects of tanshinone II(A) on isolated rat coronary arteriole and the underlying mechanisms. Coronary arterioles were carefully dissected, cannulated and pressurized. Tanshinone II(A)-elicited vascular inner diameter change was recorded by a computerized diameter tracking system. To investigate the mechanisms governing the vasodilative effects of tanshinone II(A), the roles of endothelium, endothelium-derived vasoactive factors and potassium channels were assessed respectively. Endothelium denudation, inhibition of nitric oxide synthase (NOS), inhibition of the cytochrome P450 epoxygenase, and blockade of the large conductance calcium(Ca(2+))-activated potassium channels (BKca) significantly decreased the vasodilation elicited by Tanshinone II(A). The results indicated that tanshinone II(A) induces an endothelium-dependent vasodilation in coronary arterioles; nitric oxide (NO) and cytochrome P450 metabolites contribute to the vasodilation; activation of BKca channels plays an important role in the vasodilation.

[Diagnosis and therapy of childhood thyroid carcinoma: clinical analysis of 12 cases].

OBJECTIVE: To explore the clinical characteristics, diagnosis and therapy of thyroid carcinoma in children. METHODS: Clinical data of 12 children under the age of 14 years, diagnosed as thyroid carcinoma between August 1998 and August 2008, were reviewed. RESULTS: A hard thyroid mass was observed in 10 out of 12 children with thyroid carcinoma, but only one out of 15 children with benign thyroid tumor (<0.05). The rate of cervical lymph node metastasis in children with thyroid carcinoma was significantly higher than that in children with benign thyroid tumor (<0.05). There was no significant difference in the final diagnostic rate of thyroid carcinoma between ultrasonography and CT scans (75% vs 83%; >0.05). All of 12 cases were pathologically confirmed as differentiated thyroid carcinoma, including papillary carcinoma (7 cases), follicular carcinoma (3 cases) and papillary-follicular carcinoma (2 cases). Nine patients (75%) had cervical lymph node metastasis. All patients received surgical treatment and postoperative thyroxin therapy. No patient was administered with postoperative radioiodine 131I therapy. Unilateral lobectomy plus isthmectomy along with a functional cervical lymph node dissection was a primary operation mode (83%). The follow-up period was 2 months to 10 years. The 5-and 10-year survival rates were 100%. CONCLUSIONS: Childhood thyroid carcinoma is mostly differentiated and characterized by hard thyroid mass and cervical lymph node metastasis. A combination of ultrasonography and CT is helpful to the diagnosis of childhood thyroid carcinoma. The treatment outcome may be satisfactory by optimal therapy in children with thyroid carcinoma.