3159

HMGA1

high mobility group AT-hook 1;HMGA1;high mobility group AT-hook 1

HMG-I(Y)|high mobility group protein A1|high mobility group protein HMG-I/HMG-Y|high mobility group protein R|high-mobility group (nonhistone chromosomal) protein isoforms I and Y|nonhistone chromosomal high-mobility group protein HMG-I/HMG-Y

6p21

protein-coding

The high mobility group A1 gene (HMGA1) has been previously implicated in breast carcinogenesis, and is considered an attractive target for therapeutic intervention because its expression is virtually absent in normal adult tissue. Other studies have shown that knockdown of HMGA1 reduces the tumorigenic potential of breast cancer cells in vitro. Therefore, we sought to determine if silencing HMGA1 can affect breast cancer development and metastatic progression in vivo. We silenced HMGA1 expression in the human breast cancer cell line MDA-MB-231 using an RNA interference vector, and observed a significant reduction in anchorage-independent growth and tumorsphere formation, which respectively indicate loss of tumorigenesis and self-renewal ability. Moreover, silencing HMGA1 significantly impaired xenograft growth in immunodeficient mice, and while control cells metastasized extensively to the lungs and lymph nodes, HMGA1-silenced cells generated only a few small metastases. Thus, our results show that interfering with HMGA1 expression reduces the tumorigenic and metastatic potential of breast cancer cells in vivo, and lend further support to investigations into targeting HMGA1 as a potential treatment for breast cancer.

PURPOSE: The high mobility group proteins (HMGs) include the HMGI family members HMGI-C and HMGI(Y), whose expressions in adult tissues generally correlate with malignant tumor phenotypes. The aim of this study was to assess the relationship of HMGI-C or HMGI(Y) gene expression and prognosis in colorectal cancer patients. METHODS: The gene expressions of HMGI-C and HMGI(Y) in 31 paired samples of colorectal tumor and corresponding non-tumor were determined by real-time reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: The expression of HMGI(Y) in a colorectal cancer tumor was associated with Dukes staging (p = 0.044), while, in non-tumor, the expression of this gene was significant with metastasis (p = 0.003). Patients with Dukes stage A and B present high HMGI(Y) expression in non-tumor of colorectal cancer (p = 0.006). However, patients with Dukes stage C and D present high HMGI-C expression in colorectal tumor (p = 0.023). In the non-metastasis group, HMGI(Y) was highly expressed in non-tumor of colorectal cancer. However, in the metastasis group, there was no significant difference between tumor and non-tumor tissues in both HMGI-C and HMGI(Y) gene expressions. CONCLUSIONS: The HMGI-C and HMGI(Y) quantitations by real-time RT-PCR are associated with Dukes staging and metastasis; hence, the gene expression levels may be useful in clinical practice.

tumor size indicates the extent of cell proliferation in most cases of colorectal cancer (CRC), although there are some advanced small tumors with metastases. Lymph node metastasis is a significant factor that greatly impacts disease prognosis in CRC cases. The underlying factors that cause lymph node metastasis in CRC cells are not fully understood. We investigated the mechanism that might induce CRC metastasis by focusing on smaller sized (<2 cm) invasive tumors. We carried out gene expression array analysis for CRC cases; group 1 consisted of 6 cases with tumors <2 cm with metastases, and group 2 consisted of 65 cases with tumors >2 cm without metastases. Results were validated using gene expression array data from an additional 77 cases and another bulk case set of 172 cases. Gene ontology and pathway analysis using microarray data revealed that anti-apoptotic activity had a crucial role in CRC metastasis. High mobility group A1 (HMGA1) was identified as a biomarker for poor prognosis and metastasis formation. HMGA1 expression levels were higher in lymph node-positive cases than in lymph node-negative cases, even in subgroup analysis of submucosal invasive cases. The present study strongly supports the clinical significance of HMGA1 expression as a predictive indicator of lymph node metastasis in CRC cases, even in submucosal invasive cases which could be cured by local resection.

CONCLUSION: The overexpression of HMGA1 or Ezrin may contribute to the carcinogenesis, development, and metastasis of laryngeal squamous cell carcinoma (LSCC). OBJECTIVE: To investigate the expression of HMGA1 and Ezrin in LSCC and analyze their clinical significance. METHODS: The expression of HMGA1 and Ezrin was analyzed by immunohistochemistry (IHC) in 50 cases of LSCC. Thirty cases of laryngeal polyp and 30 cases of atypical hyperplasia of larynx were studied as controls. The expression of HMGA1 and Ezrin was analyzed by real-time PCR and by Western blot in 30 cases of LSCC; samples from adjacent normal epithelial tissues in 30 cases were studied as controls. RESULTS: (1) IHC revealed that the positive rate of HMGA1 protein was 68.0% (34/50), 53.3% (16/30), and 13. 3% (4/30) in LSCC, atypical hyperplasia of larynx, and laryngeal polyp (p < 0.05), and the positive rate of Ezrin protein was 64.0% (32/50), 50.0% (15/30), and 23.3% (7/30) (p < 0.01), respectively. (2) Real-time PCR demonstrated that the mean relative mRNA expression levels of HMGA1 in LSCC and in normal tissues were 2.41 +/- 0.40 and 1.05 +/- 0.18, respectively (p < 0.01). The mRNA levels of Ezrin in LSCC and in normal tissues were 1.79 +/- 0.27 and 1.04 +/- 0.22, respectively (p < 0.05). (3) Western blotting revealed that the mean relative protein expression levels of HMGA1 in LSCC and in normal tissues were 1.73 +/- 0.60 and 0.35 +/- 0.17, respectively (p < 0.01). The protein levels of Ezrin in LSCC and in normal tissues were 1.82 +/- 0.77 and 0.42 +/- 0.20, respectively (p < 0.01).

Hepatocellular carcinoma (HCC) is one of the most common and aggressive human malignancies. Its high mortality rate is mainly a result of intra-hepatic metastases. To investigate the detailed genetic mechanisms in cancer metastasis, we compared the expression profiles of 20 HCCs with intrahepatic metastasis and 10 HCCs without intrahepatic metastasis using an oligonucleotide array. Of the approximately 12,600 genes that were analyzed, we identified 34 genes whose expression levels were significantly correlated with intrahepatic metastasis (P<0:05). Of these genes, we further investigated the expression of high-mobility group I(Y) [HMG-I(Y)] protein. Real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) confirmed that HMG-I(Y) was upregulated in HCC with intrahepatic metastasis, compared to its level in HCC without intrahepatic metastasis. Further immunohistochemical examination of HMG-I(Y) revealed a significant overexpression in HCC with intrahepatic metastasis, compared with that in HCC without intrahepatic metastasis (P<0:05). These results indicate that the molecular signatures of HCC with intrahepatic metastasis and of HCC without intrahepatic metastasis are clearly different. HMG-I(Y) expression was associated with intrahepatic metastasis and may be a predictive marker of HCC intrahepatic metastasis.

HMGA1 proteins are architectural transcription factors that are overexpressed in a range of human malignancies, including pancreatic adenocarcinoma. We hypothesized that HMGA1 expression is a determinant of cellular invasiveness and metastasis in pancreatic cancer. Stable silencing of HMGA1 in MiaPaCa2 and PANC1 pancreatic adenocarcinoma cells was achieved by transfection of short hairpin RNA-generating vectors. Additionally, stable overexpression of HMGA1 in MiaPaCa2 cells (characterized by low levels of inherent HMGA1 expression) was achieved. HMGA1 silencing resulted in significant reductions in cellular invasiveness through Matrigel; in cellular matrix metalloproteinase-9 (MMP-9) activity, mRNA levels, and gene promoter activity; and in Akt phosphorylation at Ser(473). Conversely, forced HMGA1 overexpression resulted in significant increases in cellular invasiveness; in cellular MMP-9 activity, mRNA levels, and promoter activity; and in Akt phosphorylation at Ser(473). HMGA1 overexpression-induced increases in invasiveness were MMP-9 dependent. The role of phosphatidylinositol-3 kinase (PI3K)/Akt in mediating HMGA1-dependent invasiveness was elucidated by a specific PI3K inhibitor (LY294002) and constitutively active and dominant-negative Akt adenoviral constructs. Akt-dependent modulation of MMP-9 activity contributed significantly to HMGA1 overexpression-induced increases in invasive capacity. Furthermore, HMGA1 silencing resulted in reductions in metastatic potential and tumor growth in vivo and in tumoral MMP-9 activity. Our findings suggest that HMGA1 may be a novel molecular determinant of invasiveness and metastasis, as well as a potential therapeutic target, in pancreatic adenocarcinoma.

The expression of high mobility group protein A1 (HMGA1) protein has been closely related to various malignant and prognostic degrees of tumor. To investigate the influence of down-regulating HMGA1 on the tumor and the mechanism underlying antitumor of HMGA1, we transfected the HMGA1 shRNA vector into the osteogenic sarcoma MG-63 cell and observed the changes of cell proliferation, invasion abilities, and the tumor growth. HMGA1 gene expression could be efficiently inhibited, and cell proliferation, migration, invasion, and matrix metalloprotease level were also decreased. BALB/C nude mice injected with the MG-63 cells transfected HMGA1 shRNA showed the significant lower tumor weight, tumor volume, and longer tumor-forming time compared with the control group. Our results suggest that knockdown of HMGA1 could inhibit growth and metastasis potentials of MG-63 cells, which may be a therapeutic target protein for osteogenic sarcoma and may be of biological importance.

PURPOSE: Although molecular targeted therapy has improved the clinical outcome of metastatic renal cell carcinoma, a complete response is rare and there are various side effects. Identifying novel target molecules is necessary to improve the clinical outcome of metastatic renal cell carcinoma. HMGA1 is over expressed in many types of cancer and it is associated with metastatic potential. It is expressed at low levels or not expressed in normal tissue. We examined HMGA1 expression and function in human renal cell carcinoma. MATERIALS AND METHODS: HMGA1 expression in surgical specimen from patients with renal cell carcinoma was examined by immunoblot. HMGA1 expression in 6 human renal cell carcinoma cell lines was examined by immunoblot and immunofluorescence. The molecular effects of siRNA mediated knockdown of HMGA1 were examined in ACHN and Caki-1 cells. RESULTS: Immunoblot using surgical specimen showed that HMGA1 was not expressed in normal kidney tissue but it was expressed in tumor tissue in 1 of 30 nonmetastatic (3%) and 6 of 18 metastatic (33%) cases (p=0.008). Immunoblot and immunofluorescence revealed significant nuclear expression of HMGA1 in ACHN and Caki-1 cells derived from metastatic sites. HMGA1 knockdown remarkably suppressed colony formation and induced significant apoptosis in ACHN and Caki-1 cells. HMGA1 knockdown significantly inhibited invasion and migration in vitro, and induced anoikis associated with P-Akt down-regulation in ACHN cells. CONCLUSIONS: HMGA1 is a potential target for novel therapeutic modalities for metastatic renal cell carcinoma.