Objective: To explore the expression of HAX-1 mRNA and protein in esophageal squamous cell carcinoma (ESCC) and its relation with the prognosis of patients with ESCC.Methods: The expression of HAX-1 mRNA and protein were detected with quantitative real-time RT-PCR and immunohistochemical method in 112 ESCC samples and 112 corresponding non-neoplastic samples. Survival curves were made with follow-up data. The relations of the prognosis with clinical and pathological characteristics were analyzed.Results: The expression level of HAX-1 mRNA and the strong positive rate of HAX-1 protein were significantly higher in ESCC samples (0.527 ± 0.060 and 45.54%) than that in non-neoplastic samples (0.121 ± 0.017 and 0.00%), and in ESCC samples with lymph node metastasis (0.554 ± 0.054 and 71.11%) than that in ESCC samples without lymph node metastasis (0.509 ± 0.058 and 28.36%) (allP < 0.01). HAX-1 mRNA expression level was a risk factor of lymph node metastasis in patients with ESCC (P = 0.000). There were significant differences in survival curves between lymph node metastatic group and non-metastatic group (P = 0.000), and among groups of HAX-1 protein expression +, ++and +++(,P = 0.000); but no statistical significance between male patients and female patients (P = 0.119), and between ≥60 years old patients and <60 years old patients (P = 0.705). The level of HAX-1 mRNA (P = 0.000) and protein (P = 0.005) were risk factors of survival, but lymph node metastasis (P = 0.477) was not.Conclusion: There is HAX-1 over-expression in ESCC tissue and HAX-1 mRNA level is a risk factor of lymph node metastasis. The level of HAX-1 mRNA and protein were risk factors of survival in patients with ESCC. HAX-1 may be a novel therapeutic target for ESCC treatment.Virtual slides: The virtual slide(s) for this article can be found here:http://www.diagnosticpathology.diagnomx.eu/vs/5130393079296037

Gene fusions and their products (RNA and protein) have been traditionally recognized as unique features of cancer cells and are used as ideal biomarkers and drug targets for multiple cancer types. However, recent studies have demonstrated that chimeric RNAs generated by intergenic alternative splicing can also be found in normal cells and tissues. In this study, we aim to identify chimeric RNAs in different non-neoplastic cell lines and investigate the landscape and expression of these novel candidate chimeric RNAs. To do so, we used HEK-293T, HUVEC, and LO2 cell lines as models, performed paired-end RNA sequencing, and conducted analyses for chimeric RNA profiles. Several filtering criteria were applied, and the landscape of chimeric RNAs was characterized at multiple levels and from various angles. Further, we experimentally validated 17 chimeric RNAs from different classifications. Finally, we examined a number of validated chimeric RNAs in different cancer and non-cancer cells, including blood from healthy donors, and demonstrated their ubiquitous expression pattern.

The conventional understanding that chimeric RNAs are unique to carcinoma and are the products of chromosomal rearrangement is being challenged. However, experimental evidence supporting the function of chimeric RNAs in normal physiology is scarce. We decided to focus on one particular chimeric RNA, CTNNBIP1-CLSTN1. We examined its expression in various tissues and cell types and compared it quantitatively among cancer and noncancer cells. We further investigated its role in a panel of noncancer cells and investigated the functional mechanism. We found that this fusion transcript is expressed in almost all tissues and a wide range of cell types, including fibroblasts, epithelial cells, stem cells, vascular endothelial cells, and hepatocytes. In addition, the CTNNBIP1-CLSTN1 expression level in noncancerous cell lines was not evidently different from that in cancer cell lines. Furthermore, in at least three cell types, silencing CTNNBIP1-CLSTN1 significantly reduced the cell proliferation rate by inducing G2/M arrest and apoptosis. Importantly, rescue experiments confirmed that cell cycle arrest was restored by exogenous expression of the chimera but not the wild-type parental gene. Further evidence is provided that CTNNBIP1-CLSTN1 regulates cell proliferation through SERPINE2. Thus, CTNNBIP1-CLSTN1 is an example of a new class of fusion RNAs, dubbed “housekeeping chimeric RNAs”.

BCR–ABL, the pioneering gene fusion resulting from chromosomal translocation, has marked a major milestone in understanding genetic alterations in cancer. Initially, gene fusions were linked solely to chromosomal rearrangements, serving as diagnostic markers and cancer drivers. However, advancements in high-throughput sequencing and bioinformatics have revealed additional mechanisms underlying gene fusion. The term “gene fusion” primarily refers to fusion events at the DNA level, whereas “chimeric RNA” encompasses a wide range of transcripts containing exons from different parental genes, including gene fusion transcripts. Recent developments have identified numerous chimeric RNAs in various cancer types, extending even to non-cancerous tissues. Chimeric RNAs, originating from events such as trans-splicing, read-through, and intergenic splicing, form a complex landscape with varied functions. While some chimeric RNAs have defined roles and therapeutic potential, a comprehensive understanding of their diverse functions remains a priority. Exploring the full spectrum of chimeric RNA activities is crucial for revealing their clinical and therapeutic implications. In addition, chimeric RNAs are key players in tumorigenesis, affecting cellular processes, and driving cancer progression. Understanding their intricate interactions with cellular pathways is essential for developing targeted therapies and precision medicine approaches. The dynamic nature of chimeric RNAs highlights the need for ongoing research to fully harness their diagnostic and therapeutic potential.