Increased glucose influx and glycogenesis in lung cancer cells surviving after irradiation

Abstract

Purpose

Lung cancer is considered as one of the most frequent malignancies worldwide. Radiotherapy is the main treatment modality applied for locally advanced disease, but remnant surviving cancer tissue results in disease progression in the majority of irradiated lung carcinomas. Metabolic reprogramming is regarded as a cancer hallmark and is associated with resistance to radiation therapy. Here, we explored metabolic alterations possibly related to cancer cell radioresistance.

Materials and methods

We compared the expression of metabolism-related enzymes in the parental A549 lung cancer cell line along with two new cell lines derived from A549 cells after recovery from three (A549-IR3) and six (A549-IR6) irradiation doses with 4 Gy. Differential GLUT1 and GYS1 expression on proliferation and radioresistance were also comparatively investigated.

Results

A549-IR cells displayed increased extracellular glucose absorption, and enhanced mRNA and protein levels of the GLUT1 glucose transporter. GLUT1 inhibition with BAY-876, suppressed cell proliferation and the effect was significantly more profound on A549-IR3 cells. Protein levels of molecules associated with aerobic or anaerobic glycolysis, or the phosphate pentose pathway were similar in all three cell lines. However, glycogen synthase 1 (GYS1) was upregulated, especially in the A549-IR3 cell line, suggestive of glycogen accumulation in cells surviving post irradiation. GYS1-gene silencing repressed the proliferation capacity of A549, but this increased their radioresistance. The radio-protective effect of the suppression of proliferative activity induced by GYS1 silencing did not protect A549-IR3 cells against further irradiation.

Conclusions

These findings indicate that GYS1 activity is a critical component of the metabolism of lung cancer cells surviving after fractionated radiotherapy. Targeting the glycogen metabolic reprogramming after irradiation may be a valuable approach to pursue eradication of the post-radiotherapy remnant of disease.

Keywords:

• Radiotherapy
• radioresistance
• metabolic reprogramming
• lung cancer

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.

Notes on contributors

Avgi Tsolou

Avgi Tsolou, BSc, MSc, PhD is a very qualified Post-doctoral Researcher with more than 15 years of laboratory experience. After graduating from the School of Biology, Aristotle University of Thessaloniki (2002), she completed an MSc in Molecular Genetics at Leicester University (2003) and obtained her PhD on ‘Cellular Responses to uncapped telomeres in eukaryotic cells’ from Newcastle University (2007). Work on diverse fields of Biology, ranging from Population and Evolutionary Genetics to DNA damage, Aging and Cancer has endowed her with a very good initiative in research, a broad range of molecular, cellular and biochemical techniques, a substantial troubleshooting capacity and excellent skills in organizing, work planning and applying scientific questions. Her PhD and the subsequent post-doctoral research focused on DNA damage, repair and connection with cellular senescence as a consequence. The next 10 years that followed -until today- she has focused on Cancer Research, experimenting on efficient nanoparticle-driven chemotherapy, cellular mechanisms associated with radiotherapy resistance and mitotic (dys)regulation in cancer. Moreover, as from April 2021, she has been the Facility Manager of the Microscopy Unit at the Molecular Biology and Genetics Department, Democritus University of Thrace.

Dimitrios Koparanis

Dimitrios Koparanis, is a young and hardworking scientist who is interested in cancer research. He graduated from Molecular Biology & Genetics (Democritus University of Thrace) with a graduation thesis project on ‘Comparative study of metabolic and autophagic proteins in radioresistant non-small cell lung cancer cell lines Α549’. He is an MSC student in Biomedicine & Molecular Sciences in Diagnosis and Treatment of Disease (Democritus University of Thrace) and his thesis title is ‘Correlation of radiation resistance with intracellular glucose levels and glyconeogenesis in non-small cell lung cancer cell lines’. Both graduation theses were carried out at Radiation and Oncology Laboratory, Department of Medicine, Democritus University of Thrace (PI: Prof. Michael I. Koukourakis). He is experienced in different molecular techniques used in cancer research (like Cell Culture techniques, Protein and RNA isolation, Western Blotting, PCR, Proliferation and Viability Assays) and his main areas of scientific interest are cancer metabolism, autophagy and cancer response to radiotherapy and chemotherapy.

Ioannis Lamprou

Ioannis Lamprou is a young, motivated and hardworking scientist with a background in cancer research and molecular biology, aiming to follow a professional career in a hi-tech laboratory involved in the field of cancer research. He graduated from the University of Patras in Greece, where he acquired his BSc degree in Biology (Division of Genetics, Cell and Developmental Biology), followed by an MSc degree in Molecular Pathology and Therapeutics of Cancer from the University of Leicester, UK. He recently obtained his PhD at the Department of Radiotherapy/Oncology (Radiobiology-Radiopathology Unit, Medical School, Democritus University of Thrace, Alexandroupolis, Greece) under the supervision of Professor Michael I. Koukourakis. His PhD Thesis title was’The study of Prostate Cancer (PCa) lipophagic activity and the role of lipophagy in radiotherapy and chemotherapy efficacy’. For the past four years, he has gained experience in numerous molecular techniques used in cancer research, as well as in vivo cancer monitoring. He has excellent working, communication and analytical skills; able to work effectively, both as an individual and as member of a research team. His main areas of scientific interest involve cancer metabolism, autophagy/lipophagy, cancer response to various treatment modalities and cancer immunotherapy.

Alexandra Giatromanolaki

Alexandra Giatromanolaki is head of the Department of Pathology and the Tumor Immunology Unit at the Medical School, Democritus University of Thrace. Her research focuses on translational studies for the development of tumor biomarkers related to prognosis and response to cytotoxic therapy and immunotherapy. Her published research is available at https://pubmed.ncbi.nlm.nih.gov/?term=Giatromanolaki+A

Michael I. Koukourakis

Michael I. Koukourakis is head of the Department of Radiotherapy/Oncology at the Medical School, Democritus University of Thrace and head of the Molecular Radiobiology Unit. His research interests focus on tumor resistance to radiotherapy, hypoxia, tumor metabolism, and immune response. His published research is available at https://pubmed.ncbi.nlm.nih.gov/?term=koukourakis+M