N6-methyladenosine (m6A) RNA modification in tumor immunity

Growing evidence supports that cancer progression is closely associated with the tumor microenvironment and immune evasion. Importantly, recent studies have revealed the crucial roles of epigenetic regulators in shaping the tumor microenvironment and restoring immune recognition. N⁶-methyladenosine (m⁶A) modification, the most prevalent epigenetic modification of mammalian mRNAs, has essential functions in regulating the processing and metabolism of its targeted RNAs, and therefore affects various biological processes including tumorigenesis and progression. Recent studies have demonstrated the critical functions and molecular mechanisms underlying abnormal m⁶A modification in the regulation of tumor immunity. In this review, we summarize recent research progress in the potential roles of m⁶A modification in tumor immunoregulation, with a special focus on the anti-tumor processes of immune cells and involvement in immune-associated molecules and pathways. Furthermore, we review current knowledge regarding the close correlation between m⁶A-related risk signatures and the tumor immune microenvironment landscape, and we discuss the prognostic value and therapeutic efficacy of m⁶A regulators in a variety of cancer types.     

The clinical significance of 99mTc-MIBI breast imaging in the diagnosis of early breast cancer

Objective: To find an effective, sensitive, specific and noninvasive diagnostic method of breast cancer. Methods: 109 masses of 102 patients with breast lesions smaller than 2 cm in diameter were divided into three groups to undergo ^99mTc-MIBI imaging and compared with the results of pathology examination. 20 cases without breast lesions were selected as control. Abnormal condensation of ^99mTc-MIBI in the breast reaching 10% higher than that in the counterpart of the healthy breast was regarded as positive. Results: Of 32 breast cancers, positive imaging appeared in 25. Negative imaging were found in 31 of 38 benign breast lesions. Of 39 occult breast lesions, positive imaging appeared in 6 and 3 of them were breast cancer, 2 of 3 patients with slightly increased ^99mTc-MIBI imaging threshold were breast cancer also. No positive imaging was found in the control group. The diagnostic accuracy, sensitivity, specificity, positive predictive value, negative predictive value of ^99mTc-MIBI was 88.4%, 89.2%, 88.0%, 75.0% and 95.3%, respectively. Conclusion: ^99mTc-MIBI imaging had higher sensitivity and accuracy in the diagnosis of breast cancer and differentiation between benign and malignant breast lesions. It could provide useful information for the diagnosis of clinically suspected breast cancer. Biography: Ren Chang-cai, (1951–), associate professor of general surgery, majors in breast and thyroid diseases, especially skillful on diagnosis and treatment of early stage breast cancer and treatment of advanced breast cancer.     

RNA m6A修饰与肿瘤

RNA m6A（N6-methyladenosine,m6A）修饰是由m6A甲基转移酶和去甲基化酶所调节的,整个过程是动态可逆的。m6A修饰可以调控基因的表达,在许多生命进程中发挥着重要的作用。近年来,有文章报道m6A修饰通过调节RNA稳定性,微小RNA处理,mRNA剪切和翻译,在人类肿瘤的发生发展中起着重要作用,包括肺癌、肝癌、乳腺癌、子宫内膜癌和急性髓细胞白血病等。本文总结了RNA m6A修饰与肿瘤的关系,以及RNA m6A修饰在不同肿瘤中的生物学功能,对于研究RNA m6A修饰的靶基因及其所调控的肿瘤发生和发展具有重要意义。     

Research progress concerning m6A methylation and cancer

N6-methyladenosine (m⁶A) methylation is a type of methylation modification on RNA molecules, which was first discovered in 1974, and has become a hot topic in life science in recent years. m⁶A modification is an epigenetic regulation similar to DNA and histone modification and is dynamically reversible in mammalian cells. This chemical marker of RNA is produced by m⁶A ‘writers’ (methylase) and can be degraded by m⁶A ‘erasers’ (demethylase). Methylated reading protein is the ‘reader’, that can recognize the mRNA containing m⁶A and regulate the expression of downstream genes accordingly. m⁶A methylation is involved in all stages of the RNA life cycle, including RNA processing, nuclear export, translation and regulation of RNA degradation, indicating that m⁶A plays a crucial role in RNA metabolism. Recent studies have shown that m⁶A modification is a complicated regulatory network in different cell lines, tissues and spatio-temporal models, and m⁶A methylation is associated with the occurrence and development of tumors. The present review describes the regulatory mechanism and physiological functions of m⁶A methylation, and its research progress in several types of human tumor, to provide novel approaches for early diagnosis and targeted treatment of cancer.     

6A甲基化修饰在肿瘤中的作用

N6-甲基腺苷(m6A)修饰作为表观遗传学研究的一部分,是最常见的RNA修饰之一,近年来受到越来越多的关注。m6A甲基化修饰由甲基转移酶、去甲基化酶及阅读蛋白共同动态调节。大量研究表明,m6A甲基化修饰可以通过调节与癌症相关的生物学功能来影响癌症的发生发展。本文简要介绍了m6A甲基化修饰,并对m6A甲基化修饰在不同肿瘤中的作用进行综述。     

99mTc-MIBI SPECT compared with201TI SPECT for the detection of breast cancer and lymph node metastasis

A comparative study of²⁰¹Tl and^99mTc-methoxy-2 isobutyl isonitrile (^99mTc-MIBI) was performed in 39 breast tumors.²⁰¹Tl scintigraphy was carried out in 24 breast tumors and^99mTc-MIBI scintigraphy in 15. The sensitivity of²⁰¹Tl for malignant tumors was 100% (22/22), but specificity was 0% (0/2). On^99mTc-MIBI scintigraphy, the sensitivity for malignant tumors was 83.3% (10/l2) and specificity was 100% (3/3).^99mTc-MIBI might be more useful for the diagnosis of breast tumors, because the tumor/background ratio of^99mTc-MIBI was significantly higher than that of²⁰¹T1. In addition,²⁰¹Tl scintigraphy and^99mTc-MIBI scintigraphy showed the same degree of accuracy (93.3%) in detecting lymph node metastasis. Moreover, when either ultrasonography (US) with²⁰¹Tl or^99mTc-MIBI scintigraphy was positive for lymph node metastasis, the accuracy of detection became 94.4%. The combined use of ultrasonography and scintigraphy might improve the accuracy of diagnosis of lymph node metastasis.     

N6-甲基腺嘌呤与癌症的研究进展

N6-甲基腺嘌呤(m⁶A)作为一种主要的RNA甲基化修饰,通过多种机制影响人类癌症的发生和发展。m⁶A修饰影响RNA代谢的多个方面,从RNA加工、核输出、RNA翻译到衰变。在这篇综述中,介绍了m⁶A甲基化基本概念,m⁶A甲基转移酶复合物和m⁶A去甲基化酶在几种主要癌症中的调控作用和一些作为m⁶A结合蛋白的蛋白质执行的m⁶A修饰的生物学功能。此外,还讨论了m⁶A甲基化的双重作用以及它在临床应用中的潜力。     

Radioguided Intraoperative Margins Evaluation (RIME): Preliminary results of a new technique to aid breast cancer resection

Aims

Women undergoing breast-conserving surgery for cancer can present residual disease. We have developed a technique called Radioguided Intraoperative Margins Evaluation (RIME) that uses a radiopharmaceutical to distinguish normal and cancer tissues. The aim of this study was to assess whether RIME is a feasible technique, and if it could help in breast cancer resection with free margins, minimizing residual disease.

Methods

Twenty-three breast cancer patients programmed for mastectomy were selected. Before surgery, the patients were submitted to scintimammography with ^99mTc-sestamibi to estimate the optimal time to begin radioguided surgery. Twenty patients were submitted to magnetic resonance imaging (MRI), to evaluate skin, deep fascia and to detect other tumor foci. At the beginning of the surgery, the same dose of ^99mTc-sestamibi was intravenously injected into patients. Tumor resection was performed under guidance of a gamma-probe, characterizing the RIME technique. Finally, modified radical mastectomy was performed. Tumor and residual breast were histopathologically examined.

Results

The RIME technique was successfully performed in all patients. The principal tumor was removed by this technique and provided 82.6% of histologically free margins (mean margins, 4.8 mm). Additionally, 47.8% of patients were without residual disease. The mean size of residual carcinoma was 3.67 mm and generally located near the tumor bed (<1.5 cm). There was no significant association between presence of residual disease and tumor size or margin status.

Conclusion

RIME is a feasible technique that could help tumor resection with free margins; however, it seems to be limited for small carcinoma foci.     

Methyl CpG binding protein 2 promotes colorectal cancer metastasis by regulating N6-methyladenosine methylation through methyltransferase-like 14

RNA N⁶-methyladenosine (m⁶A) is an emerging regulatory mechanism for tumor progression in several types of cancer. However, the underlying regulation mechanisms of m⁶A methylation in colorectal cancer (CRC) remain unknown. Although the oncogenic function of methyl CpG binding protein 2 (MeCP2) has been reported, it is still unclear whether MeCP2 could alter RNA m⁶A methylation state. Here, we systematically identified MeCP2 as a prometastasis gene to regulate m⁶A methylation in CRC. Interestingly, MeCP2 could bind to methyltransferase-like 14 (METTL14) to coregulate tumor suppressor Kruppel-like factor 4 (KLF4) expression through changing m⁶A methylation modification. Furthermore, insulin-like growth factor 2 mRNA-binding protein 2 recognized the unique modified m⁶A methylation sites to enhance KLF4 mRNA stability. Taken together, these findings highlight the novel function of MeCP2 for regulating m⁶A methylation and reveal the underlying molecular mechanism for the interaction between MeCP2 and METTL14, which offers a better understanding of CRC progression and metastasis.     

Significance of interleukin-6 (IL-6) in breast cancer (review)

Cytokines are factors that are known to have both tumor-promoting and inhibitory effects on breast cancer growth depending presumably on their relative concentrations and the presence of other modulating factors. Different cytokines play an important role in controlling the immune system. Interleukin-6 (IL-6) is a pleiotropic cytokine with obviously tumor-promoting and tumor-inhibitory effects. Here, we review the role of IL-6 in in vitro experiments of breast tumor cells, in breast tumor tissues (BTs) and assess its potential as a prognostic indicator in breast cancer patients. A literature search was conducted using PubMed, restricted to articles published in English language. In summary, results regarding the effect of IL-6 on breast tumor cells and on BTs are not unique indicating both tumor-promoting and inhibitory effects of IL-6. Concerning patients’ serum IL-6 levels, data are surprisingly unique showing IL-6 to be a negative prognosticator in breast tumor patients.     

FTO promotes the progression of cervical cancer by regulating the N6-methyladenosine modification of ZEB1 and Myc

Cervical cancer is a malignant tumor of the cervix in women. However, the pathogenesis of cervical cancer has not been fully understood. N6-methyladenosine (m6A) is a kind of RNA modification that plays a critical role in cancer development. We aim to find out the possible m6A regulatory mechanism of the fat mass and obesity-associated protein (FTO) on the development of cervical cancer. The proliferative capacity of cervical cancer cells was detected by 3-(4,5-dimethylthiazol-2-yl)−2,5-diphenyl-2H-tetrazolium bromide (MTT), colony formation and 5-ethynyl-20-deoxyuridine (EdU) staining. The migration and invasion of cervical cancer cells were determined by transwell assay. The function of FTO on tumor growth was evaluated by a xenograft model. We found that FTO was highly expressed in cervical cancer tissues and cell lines. FTO silencing suppressed the proliferation, migration, and invasion of cervical cancer cells. Mechanistically, FTO modulated the m6A modification of Zinc finger E-box binding homeobox 1 (ZEB1) and Myelocytomatosis oncogene (Myc). Furthermore, ZEB1 and Myc overexpression reverse the effect of FTO knockdown on the malignant behaviors of cervical cancer cells. FTO may be a novel therapeutic target for cervical cancer.     

Hormonal therapy for postmenopausal breast cancer: the science of sequencing

Upregulation of functional voltage-gated Na⁺ channels (VGSCs) occurs in metastatic human breast cancer (BCa) in vitro and in vivo. The present study aimed to ascertain the specific involvement of the ‘neonatal’ splice variant of Nav1.5 (nNav1.5), thought to be predominant, in the VGSC-dependent invasive behaviour of MDA-MB-231 cells. Functional activity of nNav1.5 was suppressed by two different methods targeting nNav1.5: (i) small interfering RNA (siRNA), and (ii) a polyclonal antibody (NESO-pAb); effects upon migration and invasion were determined. nNav1.5 mRNA, protein and signalling were measured using real-time PCR, Western blotting, and patch clamp recording, respectively. Treatment with the siRNA rapidly reduced (by ∼90%) the level of nNav1.5 (but not adult Nav1.5) mRNA, but the protein reduction was much smaller (∼30%), even after 13 days. Nevertheless, the siRNA reduced peak VGSC current density by 33%, and significantly increased the cells’ sensitivity to nanomolar tetrodotoxin (TTX). Importantly, the siRNA suppressed in vitro migration by 43%, and eliminated the normally inhibitory effect of TTX. Migrated MDA-MB-231 cells expressed more nNav1.5 protein at the plasma membrane than non-migrated cells. Furthermore, NESO-pAb reduced migration by up to 42%, in a dose-dependent manner. NESO-pAb also reduced Matrigel invasion without affecting proliferation. TTX had no effect on cells already treated with NESO-pAb. It was concluded that nNav1.5 is primarily responsible for the VGSC-dependent enhancement of invasive behaviour in MDA-MB-231 cells. Accordingly, targeting nNav1.5 expression/activity may be useful in clinical management of metastatic BCa.     

Characterization of the role of CD8+T cells in breast cancer immunity following mammaglobin-A DNA vaccination using HLA-class-I tetramers

INTRODUCTION: Mammaglobin-A(mam-A) is expressed in over 80% of human breast tumors. We recently reported that mam-A DNA vaccination resulted in breast cancer immunity in a preclinical model. Here we investigated whether mam-A HLA-class-I tetramers could be used to monitor and define the role of CD8(+)cytotoxic T-lymphocytes(CTL) in mediating breast cancer immunity following mam-A DNA vaccination. STUDY DESIGN: Mam-A DNA vaccination was performed in HLA-A2(+)huCD8(+ )transgenic mice. HLA-A2 tetramers carrying the immunodominant mamA2.1 peptide were used to monitor CD8(+)CTL. Human breast cancer colonies were developed in immunodeficient SCID-beige mice. ELISPOT was used to correlate frequency of mamA2.1 tetramer(+)CD8(+)T cells and IFN-gamma production [spots per million cells (spm)] in human subjects. RESULTS: Vaccination of HLA-A2(+)huCD8(+) mice with mam-A DNA vaccine, but not empty vector, led to the expansion of mamA2.1 tetramer(+)CD8(+)T-cells in peripheral blood (<0.5% pre-vaccination compared to >2.0% post-vaccination). CD8(+)T cells from vaccinated mice specifically lysed UACC-812(HLA-A2(+)/mam-A(+), 25% lysis) but not MDA-MB-415(HLA-A2(-)/mam-A(+)) or MCF-7(HLA-A2(+)/mam-A(-)) breast cancer cells. Adoptive transfer of purified CD8(+)T cells from vaccinated mice into immunodeficient SCID-beige mice with established human breast cancer colonies led to tetramer(+)CD8(+ )T-cell infiltration with regression of UACC-812 but not MCF-7 tumors. HLA-A2(+) breast cancer patients revealed increased frequency of mamA2.1 tetramer(+)CD8(+ )T-cells compared to normal controls (2.86 +/- 0.8% vs. 0.71 +/- 0.1%, P = 0.01) that correlated with the IFN-gamma response to mamA2.1 peptide (48.1 +/- 20.9 vs. 2.9 +/- 0.8 spm, P = 0.03). CONCLUSIONS: CD8(+ )T-cells are crucial in mediating breast cancer immunity following mam-A DNA vaccination. Mam-A HLA-class-I tetramers can be effectively used to monitor development of CD8(+ )T-cells following mam-A vaccination.     

CDK4/6抑制剂在乳腺癌治疗中的研究进展

细胞增殖、生长和分裂等过程受到细胞周期的严格调控,其调控机制在肿瘤的发生发展中发挥重要作用。近年来,多项研究显示,细胞周期蛋白依赖性激酶4和6（CDK4/6）抑制剂对于雌激素受体阳性或人类表皮生长因子受体阳性的乳腺癌患者具有较好的疗效,然而其在三阴性乳腺癌患者中的作用仍存在争议,故探究相关分子标志物以进一步筛选最能从该治疗中获益的乳腺癌人群对临床具有重要意义。此外视网膜母细胞瘤基因（Rb）也在乳腺癌中扮演关键角色,而cyclin D-CDK4/6-Rb信号通路因具有调控细胞周期限制点的作用,被认为是乳腺癌潜在的治疗靶点。本文将对CDK4/6抑制剂在乳腺癌治疗中的研究进展作一综述。     

m6A与mRNA代谢及其与恶性肿瘤关系的研究进展

N6-甲基腺嘌呤（N6-methyladenosine,m6A）为高等真核生物信使RNA（messenger RNA,mRNA）中最普遍的内部修饰,几乎影响mRNA代谢的每个步骤,包括mRNA的加工、核输出、翻译以及降解等。该修饰过程由m6A修饰酶:甲基转移酶和去甲基化酶以动态可逆的方式进行调控。此外生物体中还存在能与m6A特异性识别结合并介导其行使一定生物学功能的m6A结合蛋白。最近,越来越多的研究发现m6A与恶性肿瘤有关,有助于肿瘤干细胞的自我更新,促进恶性肿瘤细胞增殖等。m6A与恶性转化的表型及机制密切相关,表现出m6A靶向治疗人类恶性肿瘤的可能性。换言之,m6A可能成为恶性肿瘤治疗的新靶标。本文旨在对m6A如何调控mRNA代谢及其与恶性肿瘤的关系进行综述。     

乳腺癌中Axl及其配体Gas6的表达与临床意义

目的 探讨Axl与其配体生长停滞特异性蛋白6（Gas6）在乳腺癌中的表达及临床意义。方法 采用免疫组化法检测96例乳腺癌及其配对癌旁正常组织中Axl和配体Gas6蛋白的表达情况,分析两者表达与乳腺癌临床病理特征的关系。结果 Axl在乳腺癌组织中阳性表达率为62.5％,高于其在癌旁正常组织中的17.7％（P＜0.05）;Gas6在乳腺癌中阳性表达率为54.2％,高于其在癌旁正常组织中的12.5％（P＜0.05）。Axl蛋白表达与乳腺癌患者的年龄、肿瘤大小、组织学分级及c-erbB-2表达无关（P＞0.05）,与淋巴结转移、ER及PR表达有关（P＜0.05）;Gas6蛋白表达与年龄、肿瘤大小、PR表达及c-erbB-2表达无关（P＞0.05）,与淋巴结转移、组织学分级、ER表达有关（P＜0.05）。乳腺癌组织中Axl与Gas6表达呈正相关（r=0.540,P＜0.001）。结论Axl与Gas6表达与乳腺癌的发生、发展有关。     

First report of a permanent breast 103Pd seed implant as adjuvant radiation treatment for early-stage breast cancer

PURPOSE: A new technique of adjuvant partial breast irradiation using 103Pd permanent breast seed implants (PBSI) is presented. The procedure is performed in a single 1-hour session under local anesthesia. METHODS AND MATERIALS: Patients referred to a single institution for adjuvant radiotherapy after lumpectomy for an infiltrating ductal carcinoma < or = 3 cm in diameter, surgical margin > or = 2 mm, no extensive in situ carcinoma, no lymphovascular invasion, and minimal or negative lymph node involvement were offered a PBSI. RESULTS: Between May and December 2004, 31 eligible patients underwent CT scan and ultrasound simulations assessing PBSI feasibility. Fifteen were excluded because of feasibility issues, and 16 received PBSI. A minimal peripheral dose of 90 Gy was prescribed to the planning target volume corresponding to the clinical target volume identified on the CT scan plus a margin of 1 cm. The procedure was well tolerated; 56% of the patients reported no pain during the procedure, and 46% of the patients developed National Cancer Institute Common Toxicity Criteria Grade 1 acute reaction. None experienced toxicity Grade 2 or 3. CONCLUSIONS: Permanent breast seed implantation seems feasible and well tolerated on these preliminary clinical data and represents an ultimate step in the reduction of treatment fraction for partial breast irradiation.     

细胞凋亡在乳腺癌治疗中的研究进展

乳腺癌为中国女性最常见的恶性肿瘤之一,近几十年呈逐渐高发趋势。除早期手术切除以及放化疗等传统方法外,内分泌治疗和靶向治疗已成为分子分型乳腺癌治疗的常规手段。乳腺癌治疗仍然伴随易转移、易复发、易产生抗性和毒副作用大等特点。细胞凋亡阻断是包括乳腺癌在内的恶性肿瘤的最大特征。探讨乳腺癌细胞凋亡信号通路异常分子机制,诱导其重新进入凋亡周期可能是治愈乳腺癌的最根本途径。本文通过对近5年来关键细胞凋亡信号通路在诱导乳腺癌凋亡中的研究进行分析总结,进一步明确这些信号通路在乳腺癌治疗中的作用,以期找到乳腺癌治疗的特异性分子靶点。     

BRCA1 promoter methylation is associated with increased mortality among women with breast cancer

Promoter-CpG island hypermethylation has been proposed as an alternative mechanism to inactivate BRCA1 in the breast where somatic mutations of BRCA1 are rare. To better understand breast cancer etiology and progression, we explored the association between BRCA1 promoter methylation status and prognostic factors as well as survival among women with breast cancer. Promoter methylation of BRCA1 was assessed in 851 archived tumor tissues collected from a population-based study of women diagnosed with invasive or in situ breast cancer in 1996–1997, and who were followed for vital status through the end of 2002. About 59% of the tumors were methylated at the promoter of BRCA1. The BRCA1 promoter methylation was more frequent in invasive cancers (P = 0.02) and among premenopausal cases (P = 0.05). BRCA1 promoter methylation was associated with increased risk of breast cancer-specific mortality (age-adjusted HR 1.71; 95% CI: 1.05–2.78) and all-cause mortality (age-adjusted HR 1.49; 95% CI: 1.02–2.18). Neither dietary methyl intakes in the year prior to the baseline interview nor the functional polymorphisms in one-carbon metabolism were associated with BRCA1 methylation status. Our study is the first epidemiological investigation on the prognostic value of BRCA1 promoter methylation in a large population-based cohort of breast cancer patients. Our results indicate that BRCA1 promoter methylation is an important factor to consider in predicting breast cancer survival. This work was supported by grants from the National Institutes of Health (CA109753 to JC; DK55865 to SZ) and in part by grants from Department of Defense (BC031746), National Cancer Institute and the National Institutes of Environmental Health and Sciences (UO1CA/ES66572, UO1CA66572, P30CA013696, P30ES09089 and P30ES10126); and by the University of North Carolina Clinical Nutrition Research Unit (DK56350) and Center for Environmental Health and Susceptibility (ES10126). Xu, X. is a recipient of the Predoctoral Traineeship Award (W81XWH-06-1-0298) of Department of Defense Breast Cancer Research Program.     

CD4+ and CD8+ T cells have opposing roles in breast cancer progression and outcome

The Cancer Immunoediting concept has provided critical insights suggesting dual functions of immune system during the cancer initiation and development. However, the dynamics and roles of CD4⁺ and CD8⁺ T cells in the pathogenesis of breast cancer remain unclear. Here we utilized two murine breast cancer models (4T1 and E0771) and demonstrated that both CD4⁺ and CD8⁺ T cells were increased and involved in immune responses, but with distinct dynamic trends in breast cancer development. In addition to cell number increases, CD4⁺ T cells changed their dominant subsets from Th1 in the early stages to Treg and Th17 cells in the late stages of the cancer progression. We also analyzed CD4⁺ and CD8⁺ T cell infiltration in primary breast cancer tissues from cancer patients. We observed that CD8⁺ T cells are the key effector cell population mediating effective anti-tumor immunity resulting in better clinical outcomes. In contrast, intra-tumoral CD4⁺ T cells have negative prognostic effects on breast cancer patient outcomes. These studies indicate that CD4⁺ and CD8⁺ T cells have opposing roles in breast cancer progression and outcomes, which provides new insights relevant for the development of effective cancer immunotherapeutic approaches.