横纹肌肉瘤中HMGA1和HMGA2的表达及其临床意义

目的 探讨高迁移率蛋白A1(HMGA1)和高迁移率蛋白A2(HMGA2)在横纹肌肉瘤(rhabdomyosarcoma,RMS)中的表达特点及其与临床病理参数、细胞增殖的关系.方法 应用免疫组化法分别检测39例RMS和10例正常横纹肌组织中HMGA1、HMGA2和Ki-67蛋白表达水平;原位杂交法分别检测39例RMS中HMGA1和HMGA2基因mRNA的表达.结果 HMGA1和HMGA2在RMS中的蛋白阳性表达率分别为76.9%(30/39)和64.1%(25/39),表达水平分别高于正常横纹肌组织(P<0.05);mRNA阳性表达率分别为69.2%(27/39)和66.7%(26/39),表达水平分别高于正常横纹肌组织(P<0.05).HMGA1、HMGA2在蛋白水平的表达与其各自的mRNA水平表达之间具有较好一致性.两者分别在胚胎型(ERMS)和腺泡型(ARMS)中的表达差异无统计学意义(P>0.05),而在不同分化程度之间的表达差异有统计学意义(P<0.05);在有复发或转移的病例与无复发或转移的病例中表达差异有统计学意义(P<0.05);在Ki-67阳性的高增殖组与Ki-67阴性的低增殖组之间的表达差异无统计学意义(P>0.05).结论 HMGA1和HMGA2过表达可能与RMS的发生、发展密切相关,有望成为判断该肿瘤预后的指标之一,并为靶向治疗提供依据.     

HMGA gene rearrangement is a recurrent somatic alteration in polypoid endometriosis

The pathogenesis of endometriosis is unclear, and several genetic, endocrine, immune, and environmental agents have been evaluated with no putative causative factors identified. Here, we show somatic genetic alterations involving HMGA1 (6p21) and HMGA2 (12q15) in 3 cases of polypoid endometriosis. The lesions involved the small bowel mesentery and perirectal soft tissue in 1 case and the posterior vaginal fornix and sigmoid colon serosa in 2 other cases, respectively. All had a polypoid configuration with cystically dilated irregular glands and fibrotic stroma, containing thick-walled vessels. Conventional cytogenetic analysis of 1 case showed 46,XX,t(5;12)(q13;q15) in all metaphases. Fluorescence in situ hybridization studies confirmed the balanced rearrangement of HMGA2. HMGA1 rearrangements were present in 2 additional cases. Rearrangements were exclusively found in the stromal component but not in the glandular component. These findings suggest that HMGA rearrangements likely contribute to the pathogenesis of endometriosis. However, additional studies are needed to better define the biologic role of this genetic alteration.     

HMGA2 is commonly expressed in uterine serous carcinomas and is a useful adjunct to diagnosis

McCluggage W G, Connolly L E, McBride H A, Kalloger S & Gilks C B (2012) Histopathology  60, 547–553
HMGA2 is commonly expressed in uterine serous carcinomas and is a useful adjunct to diagnosis Aims: Serous carcinoma is the prototype of type 2 uterine carcinoma. In many cases, establishing a diagnosis is straightforward, but problems can arise in that papillary variants of endometrioid carcinoma may be mistaken for serous carcinoma, and glandular variants of serous carcinoma may be misdiagnosed as endometrioid carcinoma. Markers such as p53, oestrogen receptor and p16 may be of use in problematic cases, but there is overlap and these may not therefore be of value in an individual case. It has been shown recently that high‐mobility group AT‐hook 2 (HMGA2) is expressed by most ovarian serous carcinomas, and our aim was to ascertain whether it is also expressed in uterine serous carcinoma and of value in its distinction from endometrioid carcinoma. Methods and results: Whole tissue sections of uterine serous (n = 33) and endometrioid (n = 38) carcinoma were immunostained using HMGA2 antibody. As many of the diagnostic problems relate to the distinction between serous carcinoma and grade 3 endometrioid carcinoma, tissue microarrays (TMAs) containing uterine serous (n = 71) and uterine grade 3 endometrioid (n = 68) carcinomas were also stained. Staining was classified as negative (totally negative or occasional nuclei positive), 1+ (<10% of nuclei positive), 2+ (10–49% of nuclei positive), 3+ (50–74% of nuclei positive), or 4+ (≥75% of nuclei positive). On the whole tissue sections, positive staining was also classified as weak, moderate, or strong, and an immunohistochemical composite score, taking into account both extent and intensity of staining, was calculated. On whole tissue sections, there was a statistically significant difference between HMGA2 staining in serous and endometrioid carcinomas with regard to both extent and composite score, with higher expression in serous carcinomas (P < 0.0001). Thirty of 33 (91%) serous carcinomas were positive, usually with diffuse (3+ or 4+) staining. All five cases of serous endometrial intraepithelial carcinoma (EIC) (the postulated precursor of uterine serous carcinoma) were positive, as were 14 of 38 (37%) endometrioid carcinomas, usually with 1+ or 2+ staining. There was a statistically significant difference in HMGA2 staining in the TMAs between the serous and grade 3 endometrioid carcinomas, with higher expression in the former (P < 0.0001). Conclusions: Immunoreactivity for HMGA2 is diffusely positive in whole tissue sections in most uterine serous carcinomas and negative in most endometrioid carcinomas, although, as with other markers, there is overlap in individual cases. In conjunction with other markers, HMGA2 may be of value in problematic uterine carcinomas where the differential diagnosis includes serous and endometrioid carcinoma. As HMGA2 is expressed in serous EIC, this suggests that it may be implicated in the early development of uterine serous carcinoma.     

HMGA2 Is Confirmed To Be Associated with Human Adult Height

Recent genome-wide association studies have identified a novel polymorphism, rs1042725, in the HMGA2 gene for human adult height, a highly heritable complex trait. Replications in independent populations are needed to evaluate a positive finding and determine its generality. Thus, we performed a replication study to examine the associations between polymorphisms in HMGA2 and adult height in two US Caucasian populations (an unrelated sample of 998 subjects and a family-based sample of 8385 subjects) and a Chinese population (1638 unrelated Han subjects). We confirmed the association between rs1042725 in HMGA2 and adult height both in the unrelated and family-based Caucasian populations (overall P = 4.25 × 10⁻⁹). Another two SNPs (rs7968902 and rs7968682), which were in high linkage disequilibrium with rs1042725, also achieved the significance level in both Caucasian populations (overall P = 6.34 × 10⁻⁷, and 2.72 × 10⁻⁹, respectively). Our results provide strong support to the initial finding. Moreover, SNP rs1042725 was firstly found to be associated with adult height ( P = 0.008) in the Chinese population, and the effect is in the same direction as in the Caucasian populations, suggesting that it is a common variant across different populations. Our study further highlights the importance of the HMGA2 gene's involvement in normal growth.     

Prognostic significance of the MDM2/HMGA2 ratio and histological tumor grade in dedifferentiated liposarcoma

Dedifferentiated liposarcoma (DDLPS) is a relatively common soft tissue sarcoma that results from the progression of well‐differentiated liposarcoma (WDLPS). This study aimed to investigate the progression process and to clarify the pathological and genetic factors related to poor prognosis in DDLPS. In 32 DDLPS cases and five WDLPS cases, genetic factors were analyzed by custom comparative genomic hybridization (CGH) array, which was designed to densely cover gene regions known to be frequently amplified in WD/DDLPS. The analyses comparing primary and metastatic lesions and those comparing histologically different areas in the same tumor revealed intra‐tumoral genetic heterogeneity and progression. According to a prognostic analysis comparing the good‐prognosis and the poor‐prognosis groups, we selected MDM2 and HMGA2 as candidate genes associated with poor and good prognosis, respectively. The ratios of the amplification or gain levels of MDM2 and HMGA2 expressed in log ratios (log[MDM2/HMGA2] = log[MDM2]‐log[HMGA2]) were significantly associated with prognosis. An amplification or gain level of MDM2 that was more than twice that of HMGA2 (MDM2/HMGA2 > 2, log[MDM2/HMGA2] > 1) was strongly related to poor OS (P < .001) and poor distant metastasis‐free survival (DMFS) (P < .001). In the pathological analysis of 44 cases of DDLPS, histological tumor grade, cellular atypia, and MDM2 immunoreactivity were related to overall survival (OS), while HMGA2 immunoreactivity tended to be associated with OS. Cellular atypia was also associated with DMFS. In conclusion, histological grade and MDM2 expression were determined to be prognostically important, and the MDM2/HMGA2 amplification or gain ratio was found to have significant prognostic value by the custom CGH array analysis.     

Evaluating HER2 amplification and overexpression in breast cancer.

The development of Herceptin (Trazumatab) makes testing for HER2 status important for choosing optimal therapy in breast cancer. This study addresses the precision, accuracy, and reproducibility of HER2 assays. HER2 was assessed retrospectively by immunohistochemistry (IHC) with Dako 'Herceptest', by IHC with the monoclonal antibody CB11, and by fluorescence in situ hybridization (FISH, PathVysion), in a series of 216 formalin-fixed breast carcinomas including 191 for which quantitative HER2 data from radioimmunohistochemistry (Q-IHC) were available. All tests were scored independently by two observers. Positivity rates varied between Herceptest (12.6%), FISH (19.4%), and CB11 IHC (28.5%). Kappa values showed that IHC-based tests were more susceptible to inter-observer variation (kappa=0.67 and 0.74 for Herceptest and CB11, respectively) than FISH (kappa=0.973). Overall test accuracy (see the Materials and methods section) for CB11 IHC (83.8%) was lower than Herceptest (87.4%) or FISH (93.2%). FISH predicted p185 HER2 overexpression (determined by Q-IHC) better (concordance index C.Ind. 0.90) than CB11 IHC (C.Ind.=0.85) or Herceptest (C.Ind.=0.81). Of 42 cases with gene amplification by FISH, 67% were positive in the Herceptest (2+ or 3+) vs. 83% with CB11. Of 174 cases negative by FISH, 96% were negative in the Herceptest and 68% with CB11. In conclusion, FISH is the most accurate, reproducible, and precise predictor of HER2 overexpression in routine diagnostic laboratories.     

Comparative methodological analysis of erbB-2/HER-2 gene dosage, chromosomal copy number and protein overexpression in breast carcinoma tissues for diagnostic use

AIMS: This study was performed to test the validity of different methods for determining the status of the erbB-2/HER-2 oncogene in breast cancer tissues for diagnostic use. METHODS AND RESULTS: Forty formalin-fixed, paraffin-embedded breast carcinomas were investigated by fluorescence in situ and comparative genomic hybridization (FISH, CGH) as well as by immunohistochemistry (IHC) using Dako-HercepTest and CB11 antibody (Ventana). Additionally, competitive-differential polymerase chain reaction (cdPCR) was performed on frozen samples to estimate gene dosage alterations of erbB-2/HER-2. Amplification was detected in 12-23% and protein overexpression in 16-68% of the cases, depending on the methodology and/or the reagent used. Perfect concordance (100%) was found between the results of cdPCR and CB11-IHC, and a 97% concordance between FISH and CB11-IHC. The concordance between Dako-HercepTest and CB11-IHC was 78%: seven of eight 2+ carcinomas with the Dako-HercepTest were classified as nonamplified using FISH. CONCLUSIONS: Our results indicate that high-level expression as well as normal erbB-2/HER-2 status of breast carcinomas can be detected reliably both by IHC and gene dosage assessment in paraffin material for diagnostic use. However, borderline results, especially those with 2 + immunopositivity, should be interpreted with caution and increased emphasis should be given to other clinical and prognostic information available.     

Simultaneous detection of HER2/neu gene amplification and protein overexpression in paraffin-embedded breast cancer

The determination of HER2/neu status in breast carcinomas has become essential for the selection of breast cancer patients for Herceptin therapy. Herceptin treatment is used in patients with metastatic breast carcinoma with HER2/neu protein overexpression detected by immunohistochemistry (IHC) or gene amplification analysed by fluorescence in situ hybridization (FISH). A multiparametric fluorescent approach based on the simultaneous detection of HER2/neu gene amplification and protein expression was established to increase the accuracy, and to improve the reproducibility, of HER2/neu diagnostics. Based on four paraffin-embedded breast cancer cell lines, a combined fluorescent immunostaining (FIHC) and FISH method was developed by using the PathVysion HER2 DNA Probe Kit (VYSIS) and the polyclonal antibody from the HercepTest (DAKO). Diagnostic applicability was documented on 215 formalin-fixed primary breast carcinomas. Criteria for immunofluorescence quantification were chosen by analogy with the FDA-approved HercepTest scoring, ranging from 0 to 3+. There was 97.7% concordance between conventional IHC and fluorescence IHC. The FISH data resulting from the multiparametric approach did not differ from conventional FISH. Breast carcinomas with HER2/neu protein overexpression and simultaneous gene amplification were detected with 100% sensitivity. In addition, five of the 215 cases (2.3%) had HER2/neu gene amplification without protein overexpression. The main advantage of this novel approach is that polysomy, aneuploidy, gene amplification, and protein content can be analysed simultaneously in the same cell.     

胃癌中HMGA2与HDAC6表达的临床意义及其相关性

目的检测胃癌中高迁移率族蛋白2(HMGA2)和组蛋白去乙酰化酶6(HDAC6)在胃癌中的表达情况及相关关系,分析其与临床病理特征的关系。方法分别用免疫组织化学法、Western blot和real-time PCR检测82例配对人胃癌、癌旁及正常组织中HMGA2和HDAC6的蛋白及mRNA表达,并分析其与临床病理参数的关系及两者表达的相关性。结果胃癌组织中HMGA2和HDAC6蛋白阳性表达率分别为69.51%(57/82)和65.85%(54/82),明显高于癌旁组织14.63%(12/82)、12.20%(10/82)和正常组织9.76%(8/82)、7.32%(6/82)(P0.05);胃癌组织HMGA2、HDAC6蛋白和mRNA表达较癌旁组织及正常组织高(P0.05),且两者表达水平与肿瘤的临床分期和淋巴结转移相关(P0.05);HMGA2和HDAC6在胃癌组织中的表达呈明显正相关(r=0.56,P0.05)。结论 HMGA2和HDAC6基因在胃癌组织中存在高表达且共存现象,可能与胃癌恶性程度有关。     

HMGA2在胃癌细胞上皮-间充质转化中的作用

目的:探讨HMGA2在胃癌细胞上皮-间充质转化(EMT)中的作用及机制。方法:采用Western blot和RT-qPCR实验检测不同分化程度的人胃癌细胞株MKN45、MKN28和SGC7901以及人永生化胃黏膜上皮细胞株GES-1中HMGA2的表达水平;采用脂质体转染法将pcDNA3.0-HMGA2质粒转染至MKN28细胞中,将si-HMGA2干扰片段转染至MKN45细胞中,并采用Western blot和RT-qPCR实验检测转染效率;CCK-8实验检测HMGA2上调对MKN28细胞活力的影响以及HMGA2下调对MKN45细胞活力的影响;采用细胞迁移和侵袭实验检测HMGA2上调对MKN28细胞迁移和侵袭能力的影响;采用Western blot和RT-qPCR实验检测HMGA2过表达对MKN28细胞EMT相关标志蛋白上皮型钙黏蛋白(E-cadherin)、神经型钙黏蛋白(N-cadherin)和波形蛋白(vimentin)表达的影响以及敲减HMGA2表达对MKN45细胞E-cadherin、N-cadherin和vimentin表达的影响;采用RT-qPCR实验检测过表达HMGA2的MKN28细胞Wnt/β-catenin信号通路相关分子表达的变化。结果:HMGA2在不同分化程度的胃癌细胞中的表达水平是不同的(P0.05)。上调MKN28细胞HMGA2的表达水平能够抑制细胞活力(P0.05);而在MKN45细胞中下调HMGA2的表达水平能够增强细胞活力(P0.05)。上调MKN28细胞HMGA2的表达水平能够促进细胞的迁移和侵袭能力(P0.05),且E-cadherin表达降低,N-cadherin和vimentin表达升高(P0.05);敲减HMGA2在MKN45细胞的表达水平使E-cadherin表达升高,而N-cadherin和vimentin表达降低(P0.05)。上调MKN28细胞中HMGA2的表达水平,细胞内Wnt/β-catenin通路的β-catenin及其下游分子c-Myc和cyclin D1的mRNA表达水平显著增加(P0.05)。结论:HMGA2与胃癌细胞迁移和侵袭能力密切相关,并且能够通过激活细胞内Wnt/β-catenin通路,促进胃癌细胞EMT。     

Comparative analysis of AKT and the related biomarkers in uterine leiomyomas with MED12, HMGA2, and FH mutations

Uterine leiomyomas (ULM) are histologically and molecularly heterogeneous and clinically they grow at vastly different rates. Several driver gene mutations have been identified in ULM, including MED12 mutations, HMGA2 overexpression, and biallelic FH inactivation. ULM with different driver mutant genes may use different molecular pathways, but currently no clear correlation between gene mutations and growth related pathways has been established. To better define this relationship, we collected ULM with MED12 (n = 25), HMGA2 (n = 15), and FH (n = 27) mutations and examined the sex steroid hormone, cell cycle, and AKT pathway genes by immunohistochemistry. While ER and PR were highly expressed in all types of ULM, FH ULM showed lower ER expression and higher PR expression. HMGA2 tumors had significantly higher levels of AKT signaling and mitogenic activity than other ULM types. HMGA2 activated AKT signaling through upregulation of IGF2BP2. Silencing HMGA2 in ULM cells resulted in downregulation of AKT and upregulation of p16 and p21, which eventually led to cell senescence. HMGA2 overexpression in ULM is not only related to tumor development but also plays a role in controlling cellular proliferation through the AKT pathway.     

下调HMGA2基因表达对改善骨肉瘤U2OS细胞恶性表型的实验研究

目的:研究HMGA2表达在维持人骨肉瘤U2OS细胞恶性表型中的作用,为基因靶向治疗提供理论依据。方法:采用基于DNA的shRNA表达载体HMGA2-shRNA,稳定转染人骨肉瘤U2OS细胞,下调其HMGA2表达水平,并应用RT-PCR技术检测其对HMGA2基因的沉默效果;经Cell Counting Kit-8(CCK8)测定、Hoechst33342染色荧光显微镜观察及Boyden小室法分别检测细胞增殖、凋亡及迁移情况;实时定量RT-PCR检测mRNAs表达水平。结果:稳定转染靶向HMGA2的shRNA可特异性下调U2OS细胞HMGA2 mRNA表达水平;其作用结果使细胞的增殖和迁移能力受到明显抑制,自发凋亡率及Caspase 3和Caspas 9基因表达水平显著升高。结论:HMGA2基因异常表达在维持人骨肉瘤U2OS细胞恶性表型中起重要作用,靶向HM-GA2的基因治疗可能为骨肉瘤治疗带来新希望。