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

MiRNA29a-3p negatively regulates ISL1-Integrin β1 axis to suppress gastric cancer progression

Insulin gene enhancer protein 1 (ISL1) belongs to the LIM homeodomain transcription factor family, which is closely related to the development of several cancers. We previously found that abnormally high ISL1 expression is involved in gastric cancer (GC) metastasis. However, the specific role of ISL1 and its regulatory mechanisms in GC metastasis warrant elucidation. In this study, we found that ISL1 is highly expressed in GC tissues and positively correlated with GC development, promoting cell migration and invasion in vivo and in vitro. Moreover, miRNA29a-3p can target ISL1 and thus inhibit GC cell migration. Furthermore, ISL1 upregulates ITGB1 by binding to its enhancer; nevertheless, ISL1-ITGB1 axis expression can be regulated using miRNA29a-3p. In GC cell nuclei, ISL1 and annexin A2 (ANXA2) form a transcriptional activator complex at the ITGB1 enhancer, thus promoting ITGB1 expression. In GC cell cytoplasm, the ISL1-ANXA2 complex synergistically activates matrix metalloproteinases, thus promoting cell migration. In conclusion, ISL1 is a potential therapeutic target for GC.

Phosphorylation of islet-1 serine 269 by CDK1 increases its transcriptional activity and promotes cell proliferation in gastric cancer

Background

Despite recent advances in diagnostic and therapeutic approaches for gastric cancer (GC), the survival of patients with advanced GC remains very low. Islet-1 (ISL1) is a LIM-homeodomain transcription factor, which is upregulated and promotes cell proliferation in GC. The exact mechanism by which ISL1 influences GC development is unclear.

Methods

Co-immunoprecipitation (co-IP) and glutathione S-transferase (GST)-pulldown assays were employed to evaluate the interaction of ISL1 with CDK1. Western blot and immunohistochemistry analyses were performed to evaluate the ability of CDK1 to phosphorylate ISL1 at Ser 269 in GC cell and tissue specimens. Chromatin immunoprecipitation (ChIP), ChIP re-IP, luciferase reporter, and CCK-8 assays were combined with flow cytometry cell cycle analysis to detect the transactivation potency of ISL1-S269-p and its ability to promote cell proliferation. The self-stability and interaction with CDK1 of ISL1-S269-p were also determined.

Results

ISL1 is phosphorylated by CDK1 at serine 269 (S269) in vivo. Phosphorylation of ISL1 by CDK1 on serine 269 strengthened its binding on the cyclin B1 and cyclin B2 promoters and increased its transcriptional activity in GC. Furthermore, CDK1-dependent phosphorylation of ISL1 correlated positively with ISL1 protein self-stability in NIH3T3 cells.

Conclusions

ISL1-S269-p increased ISL1 transcriptional activity and self-stability while binding to the cyclinB1 and cyclinB2 promoters promotes cell proliferation. ISL1-S269-p is therefore crucial for tumorigenesis and potentially a direct therapeutic target for GC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00302-6.

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.

Kindlin-2 links mechano-environment to proline synthesis and tumor growth

Cell metabolism is strongly influenced by mechano-environment. We show here that a fraction of kindlin-2 localizes to mitochondria and interacts with pyrroline-5-carboxylate reductase 1 (PYCR1), a key enzyme for proline synthesis. Extracellular matrix (ECM) stiffening promotes kindlin-2 translocation into mitochondria and its interaction with PYCR1, resulting in elevation of PYCR1 level and consequent increase of proline synthesis and cell proliferation. Depletion of kindlin-2 reduces PYCR1 level, increases reactive oxygen species (ROS) production and apoptosis, and abolishes ECM stiffening-induced increase of proline synthesis and cell proliferation. In vivo, both kindlin-2 and PYCR1 levels are markedly increased in lung adenocarcinoma. Ablation of kindlin-2 in lung adenocarcinoma substantially reduces PYCR1 and proline levels, and diminishes fibrosis in vivo, resulting in marked inhibition of tumor growth and reduction of mortality rate. Our findings reveal a mechanoresponsive kindlin-2-PYCR1 complex that links mechano-environment to proline metabolism and signaling, and suggest a strategy to inhibit tumor growth.

ISL1 promotes cancer progression and inhibits cisplatin sensitivity in triple-negative breast cancer cells

Triple‑negative breast cancer (TNBC) is a type of breast cancer that is characterized by the lack of expression of estrogen and progesterone receptors, and epidermal growth factor receptor 2. Therefore, there is an absence of a specific target for effective therapy in TNBC. Cisplatin is usually employed as a first‑line chemotherapy agent for patients with TNBC. However, resistance remains an obstacle for cisplatin‑based chemotherapy, due to its elusive underlying mechanism. Previously, abnormal expression of Islet 1 (ISL1) was demonstrated to be closely associated with cancer development and progression. The present study revealed that (ISL1) was significantly upregulated in TNBC tissues in comparison with adjacent normal tissues. Overexpression of ISL1 markedly promoted the proliferation and invasion of the TNBC MDA‑MB‑231 and MDA‑MB‑468 cell lines, while knockdown of ISL1 inhibited cell invasion and proliferation in these cell lines. In addition, overexpression of ISL1 reversed cisplatin‑induced cell apoptosis, while knockdown of ISL1 enhanced apoptosis following cisplatin treatment in MDA‑MB‑231 and MDA‑MB‑468 cells. Furthermore, the levels of the anti‑apoptotic proteins, phosphorylated‑protein kinase B and B‑cell lymphoma‑2 (Bcl‑2), were significantly decreased, while the levels of the pro‑apoptotic protein Bcl‑2‑associated X protein were remarkably increased in response to cisplatin treatment. The present study revealed that ISL1 overexpression reversed the protein expression profile of p‑Akt, Bcl‑2 and Bax, while ISL1 knockdown promoted cell apoptosis. Therefore, the data of the present study demonstrated that ISL1 contributes to TNBC progression and reverses cell sensitivity towards cisplatin in TNBC cells, suggesting that ISL1 is a potential therapeutic target for the treatment of TNBC.

Genome-wide Analyses on Single Disease Samples for Potential Biomarkers and Biological Features of Molecular Subtypes: A Case Study in Gastric Cancer

Purpose: Based on the previous 3 well-defined subtypes of gastric adenocarcinoma (invasive, proliferative and metabolic), we aimed to find potential biomarkers and biological features of each subtype.

Methods: The genome-wide co-expression network of each subtype of gastric cancer was firstly constructed. Then, the functional modules in each genome-wide co-expression network were divided. Next, the key genes were screened from each functional module. Finally, the enrichment analysis was performed on the key genes to mine the biological features of each subtype. Comparative analysis between each pair of subtypes was performed to find the common and unique features among different subtypes.

Results: A total of 207 key genes were identified in invasive, 215 key genes in proliferative, and 204 key genes in metabolic subtypes. Most key genes in each subtype were unique and new findings compared with that of the existing related researches. The GO and KEGG enrichment analyses for the key genes of each subtype revealed important biological features of each subtype.

Conclusions: For a subtype, most identified key genes and important biological features were unique, which means that the key genes can be used as the potential biomarker of a subtype, and each subtype of gastric cancer might have different occurrence and development mechanisms. Thus, different diagnosis and therapy methods should be applied to the invasive, proliferative and metabolic subtypes of gastric cancer.

ISL1, a novel regulator of CCNB1, CCNB2 and c-MYC genes, promotes gastric cancer cell proliferation and tumor growth

Islet-1 (ISL1) belongs to the LIM homeodomain transcription factor family, which is specifically expressed in certain tissue types only. Previously, we reported that ISL1 is aberrantly overexpressed in gastric cancer (GC). However, its role in GC is not clear. Here, we report that ISL1 is aberrantly upregulated not only in human gastric carcinoma tissues but also in some GC cell lines. Upregulated ISL1 expression enhanced xenografted gastric carcinoma development, while ISL1 knockdown inhibited GC growth in nude mice. ISL1 overexpression promoted GC cell proliferation, colony formation, and cell growth in soft agar, and facilitated cell cycle transition in GC cells, demonstrated an increase in the proportion of cells in the G₂/M and S phases and a decrease in the proportion of cells in the G₁ phase. Furthermore, we provide evidence that ISL1 is a novel regulator of the cyclin B1 (CCNB1), cyclin B2 (CCNB2) and c-myc (c-MYC) genes. ISL1 activated the expression of these genes in GC cells by binding to the conserved binding sites on their promoters or enhancers. The expression levels of the genes were decreased in response to ISL1 knockdown. Therefore, ISL1 may serve as a potential therapeutic target in GC.