A positive feedback regulation of ISL-1 in DLBCL but not in pancreatic β-cells

The Role of ISL1 and LHX5 LIM Homeobox Genes in Bladder Tumourigenesis

Introduction

Lin-11, Isl-1 and Mec-3 domains (LIM) homeobox genes are among the most important sub-families of homeobox genes. These genes are thought to play an important role in cancer. In this study, the protein expression of these genes was examined in urothelial carcinoma of the bladder. The expression pattern of Islet-1 (ISL1) and LIM homeobox 5 (LHX5) across different cancer stages and grades, as well as the association between the protein expression of these genes and patient demographics and clinicopathological features, were examined.

Methods

A total of 100 formalin-fixed paraffin-embedded urothelial carcinoma tissues were selected from the Department of Pathology, Hospital Kuala Lumpur and the protein expression of ISL1 and LHX5 was determined using immunohistochemistry.

Results

Positive expression of ISL1 and LHX5 was detected in 94% and 98% of the samples, respectively. There were no distinct LHX5 expression patterns associated with different cancer stages, but the proportion of high-expressing tumours was higher in high-grade tumours. In addition, there was a significant association between the expression of LHX5 and tumour grade. The proportion of tumours expressing high levels of ISL1 was found to be highest in later stage tumours.

Conclusion

The high percentage of tumours expressing both these genes suggests that ISL1 and LHX5 play an important role in bladder tumourigenesis across multiple stages.

ISL-1 promotes pancreatic islet cell proliferation by forming an ISL-1/Set7/9/PDX-1 complex

Islet-1 (ISL-1), a LIM-homeodomain transcription factor, has been recently found to be essential for promoting postnatal pancreatic islet proliferation. However, the detailed mechanism has not yet been elucidated. In the present study, we investigated the mechanism by which ISL-1 promotes β-cell proliferation through regulation of CyclinD1 in HIT-T15 and NIT-1 cells, as well in rat islet mass. Our results provide the evidence that ISL-1 promotes adult pancreatic islet β-cell proliferation by activating CyclinD1 transcription through cooperation with Set7/9 and PDX-1 to form an ISL-1/Set7/9/PDX-1 complex. This complex functions in an ISL-1-dependent manner, with Set7/9 functioning not only as a histone methyltransferase, which increases the histone H3K4 tri-methylation of the CyclinD1 promoter region, but also an adaptor to bridge ISL-1 and PDX-1, while PDX-1 functions as a RNA pol II binding modulator. Furthermore, the formation of the ISL-1/Set7/9/PDX-1 complex is positively associated with insulin-like growth factor-1 treatment in NIT and HIT-T15 cells in vitro, while may be negatively correlated with age in vivo.

Expression of SOX11, PAX5, TTF-1 and ISL-1 in medulloblastoma

The aim of our study was to evaluate the immunohistochemical expression of SOX11, PAX5, TTF-1 and ISL-1 in medulloblastoma (MB) to investigate their diagnostic usefulness.

METHODS

Immunohistochemical expression of PAX5 (two antibodies: Dako, DAK-Pax5; and BD, clone 24), TTF-1 (Dako, 8G7G3/1), SOX11 (CL0142; Abcam) and ISL-1 (1 H9, Abcam) was analyzed using the h-score and Remmele score in 25 cases of MB.

RESULTS

There were 18 MBs of classic and 7 of desmoplastic type. SOX11 was strongly expressed in all tumors. The expression of PAX5 was higher and more frequent in a case of DAK-Pax5 clone (25/25) than clone 24 (6/25). ISL-1 was positive in 11 (44%) and TTF-1 in 3 (12%) cases. ISL-1 expression correlated positively (p<0.001), while TTF-1 correlated negatively with the age of patients (p=0.039). PAX5 expression correlated with ISL-1 (p=0.039) and showed a trend toward higher expression in the desmoplastic subtype (p=0.069).

CONCLUSIONS

SOX11 is strongly and robustly expressed in MBs. PAX5 expression pattern differs substantially among two antibody clones. TTF-1 and ISL-1 is associated with the age of patients.

An abnormally high expression of ISL-1 represents a potential prognostic factor in gastric cancer

Insulin gene enhancer binding protein-1 (ISL-1) is a transcription factor involved in development of the heart, motor neurons, and pancreas. Our previous study indicated that ISL-1 was overexpressed in gastric cancer but not in other gastrointestinal tumors. However, no immunohistochemical or clinicopathological studies of ISL-1 in gastric carcinoma have been performed. The aim of this study was to determine the expression and prognostic value of ISL-1 in gastric carcinoma. A nude mouse xenograft model was established to study the role of ISL-1 on cancer genesis and development in vivo. Overexpression of ISL-1 significantly enhanced the tumorigenicity of NIH3T3 cells in vivo. ISL-1 expression was evaluated using immunohistochemistry in 456 human gastric carcinoma and normal tissues. ISL-1 was significantly overexpressed in gastric adenocarcinoma compared with normal gastric tissues. ISL-1 expression was significantly associated with depth of invasion, lymph node metastasis, TNM stage, and histological grade (P < .05, χ(2) test). Positive ISL-1 expression was associated with poorer 5-year overall survival in gastric cancer (P = .001, log-rank test). Multivariate Cox regression analysis demonstrated that ISL-1 expression (P = .047) could be an independent prognostic factor for overall survival in gastric carcinoma. This study suggests that ISL-1 may be a useful prognostic biomarker and may represent a novel therapeutic target for gastric adenocarcinoma.