Down-regulation of XIAP enhances the radiosensitivity of esophageal cancer cells in vivo and in vitro. Biosci Rep. 2017;37. [PMID: 28821565 PMCID: PMC5603754 DOI: 10.1042/bsr20170711]

The development of radioresistant oral squamous carcinoma cell lines and identification of radiotherapy-related biomarkers

BACKGROUND

In the treatment of oral squamous cell carcinoma (OSCC), radiation resistance remains an important obstacle to patient outcomes. Progress in understanding the molecular mechanisms of radioresistance has been limited by research models that do not fully recapitulate the biological features of solid tumors. In this study, we aimed to develop novel in vitro models to investigate the underlying basis of radioresistance in OSCC and to identify novel biomarkers.

METHODS

Parental OSCC cells (SCC9 and CAL27) were repeatedly exposed to ionizing radiation to develop isogenic radioresistant cell lines. We characterized the phenotypic differences between the parental and radioresistant cell lines. RNA sequencing was used to identify differentially expressed genes (DEGs), and bioinformatics analysis identified candidate molecules that may be related to OSCC radiotherapy.

RESULTS

Two isogenic radioresistant cell lines for OSCC were successfully established. The radioresistant cells displayed a radioresistant phenotype when compared to the parental cells. Two hundred and sixty DEGs were co-expressed in SCC9-RR and CAL27-RR, and thirty-eight DEGs were upregulated or downregulated in both cell lines. The associations between the overall survival (OS) of OSCC patients and the identified genes were analyzed using data from the Cancer Genome Atlas (TCGA) database. A total of six candidate genes (KCNJ2, CLEC18C, P3H3, PIK3R3, SERPINE1, and TMC8) were closely associated with prognosis.

CONCLUSION

This study demonstrated the utility of constructing isogenic cell models to investigate the molecular changes associated with radioresistance. Six genes were identified based on the data from the radioresistant cells that may be potential targets in the treatment of OSCC.

miR-431-5p regulates cell proliferation and apoptosis in fibroblast-like synoviocytes in rheumatoid arthritis by targeting XIAP

BACKGROUND

miR-431-5p is dysregulated in various cancers and plays an important function in the development of cancer. However, its role in fibroblast-like synoviocytes (FLSs) in patients with rheumatoid arthritis (RA) remains to be understood.

METHODS

Quantitative real-time polymerase chain reaction was used to detect the relative expression of miR-431-5p in synovial tissues and FLSs. Cell proliferation assays helped examine RA FLS proliferation. Flow cytometry was performed to determine apoptosis and cell cycle progression in RA FLSs. We used dual-luciferase assays to determine the correlation between miR-431-5p and its putative target, X-linked inhibitor of apoptosis (XIAP). Quantitative real-time PCR and western blotting were used to measure XIAP levels in synovial tissues and transfected RA FLSs.

RESULTS

miR-431-5p was downregulated in synovial tissues and FLSs of patients with RA. Upregulation of miR-431-5p prohibited cell proliferation and the G0/G1-to-S phase transition but promoted apoptosis in RA FLSs, while miR-431-5p inhibition showed the opposite results. miR-431-5p directly targeted XIAP in RA FLSs and reversely correlated with XIAP levels in synovial tissues. Notably, XIAP silencing partially restored the effects of miR-431-5p inhibition in RA FLSs.

CONCLUSION

miR-431-5p regulates cell proliferation, apoptosis, and cell cycle of RA FLSs by targeting XIAP, suggesting its potential in the treatment of RA.

Targeting hallmarks of cancer to enhance radiosensitivity in gastrointestinal cancers

Radiotherapy is used in the treatment of approximately 50% of all malignancies including gastrointestinal cancers. Radiation can be given prior to surgery (neoadjuvant radiotherapy) to shrink the tumour or after surgery to kill any remaining cancer cells. Radiotherapy aims to maximize damage to cancer cells, while minimizing damage to healthy cells. However, only 10-30% of patients with rectal cancer or oesophageal cancer have a pathological complete response to neoadjuvant chemoradiation therapy, with the rest suffering the negative consequences of toxicities and delays to surgery with no clinical benefit. Furthermore, in pancreatic cancer, neoadjuvant chemoradiation therapy results in a pathological complete response in only 4% of patients and a partial pathological response in only 31%. Resistance to radiation therapy is polymodal and associated with a number of biological alterations both within the tumour itself and in the surrounding microenvironment including the following: altered cell cycle; repopulation by cancer stem cells; hypoxia; altered management of oxidative stress; evasion of apoptosis; altered DNA damage response and enhanced DNA repair; inflammation; and altered mitochondrial function and cellular energetics. Radiosensitizers are needed to improve treatment response to radiation, which will directly influence patient outcomes in gastrointestinal cancers. This article reviews the literature to identify strategies - including DNA-targeting agents, antimetabolic agents, antiangiogenics and novel immunotherapies - being used to enhance radiosensitivity in gastrointestinal cancers according to the hallmarks of cancer. Evidence from radiosensitizers from in vitro and in vivo models is documented and the action of radiosensitizers through clinical trial data is assessed.

Value of long non-coding RNA Rpph1 in esophageal cancer and its effect on cancer cell sensitivity to radiotherapy

BACKGROUND

Esophageal cancer is a common digestive tract tumor that is generally treated with radiotherapy. Poor responses to radiotherapy in most patients generally result in local radiotherapy failure, so it is essential to find new radiosensitizers that can enhance the response of cancer cells to radiotherapy and improve the survival of esophageal cancer patients with radiation resistance. The long non-coding RNA (lncRNA) Rpph1 is highly expressed in human gastric cancer tissues, and represses breast cancer cell proliferation and tumorigenesis. However, the expression of lncRNA Rpph1 in esophageal cancer and its relationship with radio-sensitivity has not been studied.

AIM

To explore the value of lncRNA Rpph1 in esophageal cancer and its effect on cancer cell sensitivity to radiotherapy.

METHODS

Eighty-three patients with esophageal cancer admitted to Qilu Hospital of Shandong University and 90 healthy participants who received physical examinations were collected as research participants. The expression of Rpph1 was determined by qRT-PCR. siRNA-NC and siRNA-Rpph1 were transfected into esophageal cancer cell lines, and cells without transfection were designated as the blank control group. Cell survival was tested by colony formation assays, and the levels of proteins related to apoptosis and epithelial-mesenchymal transitions were determined by Western blot assays. Cell proliferation was assessed by MTT assays, cell apoptosis by flow cytometry, and cell migration by wound-healing assays. Changes in cell cycle distribution were monitored.

RESULTS

Rpph1 was highly expressed in esophageal carcinoma, making it a promising marker for the diagnosis of esophageal cancer. Rpph1 could also be used to distinguish different short-term responses, T stages, N stages, and clinical stages of esophageal cancer patients. The results of 3-year overall survival favored patients with lower Rpph1 expression over patients with higher Rpph1 expression (P < 0.05). In vitro and in vivo experiments showed that silencing Rpph1 expression led to higher sensitivity of esophageal cancer cells to radiotherapy, stronger apoptosis in esophageal cancer cells induced by radiotherapy, higher expression of Bax and caspase-3, and lower expression of Bcl-2 (Bax, caspase-3, and Bcl-2 are apoptosis-related proteins). Additionally, silencing Rpph1 attenuated radiation-induced G2/M phase arrest, and significantly inhibited the expression of proteins involved in cell proliferation, migration, and epithelial-mesenchymal transition regulation in esophageal cancer cells.

CONCLUSION

Rpph1 is highly expressed in esophageal cancer. Silencing Rpph1 expression can promote cell apoptosis, inhibit cell proliferation and migration, and increase radio-sensitivity.

Expression of inhibitors of apoptosis proteins in salivary gland adenoid cystic carcinoma: XIAP is an independent marker of impaired cause-specific survival

Objectives

Inhibitors of apoptosis proteins are crucial to carcinogenesis since their expression results in evasion of apoptosis. Overexpression of inhibitors of apoptosis has repeatedly been associated with resistance to treatment and poor prognosis in various cancers. The role of inhibitors of apoptosis in adenoid cystic carcinoma of the salivary gland is still unclear. The aim of this study was to investigate the expression of inhibitors of apoptosis and their potential prognostic value in adenoid cystic carcinoma.

Design, setting and participants

Forty‐nine patients, diagnosed with adenoid cystic carcinoma of the salivary gland between 1996 and 2016, were retrospectively included in this study. The expression of cIAP1, cIAP2, XIAP, Birc6, Livin and Survivin was assessed using immunohistochemistry, and their association of survival and prognosis was evaluated during a median follow‐up of 6.4 years.

Main outcome measure

Cause‐specific survival and recurrence‐free survival rates.

Results

XIAP, cIAP2, Livin and nuclear Survivin showed high expression levels in adenoid cystic carcinoma in most patients. There was no significant association of cIAP1, cIAP2, Livin, Birc6 and Survivin with outcome. However, high XIAP expression was associated with worse cause‐specific survival and worse response to radiotherapy and proved to be an independent marker in multivariable analysis.

Conclusion

Our data indicate that high expression of XIAP may be used as a prognosticator for poor survival and poor response to radiotherapy in adenoid cystic carcinoma patients.

Knockdown of C1GalT1 inhibits radioresistance of human esophageal cancer cells through modifying β1-integrin glycosylation

Radiotherapy has played a limited role for the treatment of human esophageal cancer owing to the risk of tumor radioresistance. Core 1 β1, 3-galactosyltransferase (C1GalT1), which catalyzes the formation of core 1 O-glycan structures, is frequently overexpressed during tumorigenesis. However, the exact effects and mechanisms of C1GalT1 in the radioresistance of esophageal cancer remain unclear. In this study, Public databases and our data revealed that C1GalT1 expression was up-regulated in esophageal cancer tissues and was associated with poor survival. Upon irradiation, we found that esophageal cancer cells with high levels of C1GalT1 could tolerate cell death and had increased resistance to radiotherapy. Irradiation also promoted the expression of C1GalT1 and core 1 O-glycan structures. C1GalT1 knockdown increased the radiosensitivity of esophageal cancer cells, and attenuated irradiation-enhanced migration and invasion. Mechanistic investigations showed that C1GalT1 modified O-glycan structures on β1-integrin and regulated its downstream focal adhesion kinase (FAK) signaling. Furthermore, β1-integrin-blocking antibody and FAK inhibitor enhanced radiation-induced apoptosis in esophageal cancer cells. Together, our results indicate that C1GalT1 is a major determinant of radioresistance via modulation of β1-integrin glycosylation. C1GalT1 may be a potent molecular target for enhancing the efficacy of radiotherapy.