Circulating Tumor Cells in Cellular Oncology: Clinical Implications

Labard Baras^*
*Correspondence: Labard Baras, Department of Interdisciplinary Oncology, Iran National Standard Organization, Tehran, Iran, Email:

Keywords

Tumor cells • Cancer • ATP • Oxidative phosphorylation

Introduction

Tumor cells can originate from various types of tissue in the body, leading to different types of cancer. Common types of cancer include breast cancer, lung cancer, prostate cancer, colon cancer, and leukaemia, among many others. Each type of cancer has its own characteristics, including the way it grows, spreads, and responds to treatment. Cancer is a complex disease, and its development often involves a combination of genetic, environmental, and lifestyle factors. Treatment options for cancer may include surgery, chemotherapy, radiation therapy, immunotherapy, targeted therapy, and hormone therapy, depending on the type and stage of cancer. Early detection and diagnosis of cancer are crucial for effective treatment and improved outcomes. Regular screenings, such as mammograms and colonoscopies, along with lifestyle modifications like a healthy diet and avoiding tobacco and excessive alcohol use, can help reduce the risk of developing cancer and increase the chances of successful treatment if it does occur. In early studies on energy metabolism of tumor cells, it was proposed that the enhanced glycolysis was induced by a decreased oxidative phosphorylation. Since then it has been indiscriminately applied to all types of tumor cells that the ATP supply is mainly or only provided by glycolysis, without an appropriate experimental evaluation. In this review, the different genetic and biochemical mechanisms by which tumor cells achieve an enhanced glycolytic flux are analysed [1-3].

Literature Review

It is noted that in hypoxic regions of tumors, O2 levels are not a limiting factor for OXPHOS to function. This suggests that other factors are influencing the decreased reliance on OXPHOS in tumor cells. The passage suggests that the decreased reliance on OXPHOS may be related to the types of substrates (fuels) that tumor cells use for energy production. Tumor cells may preferentially utilize glycolysis (a less efficient but oxygen-independent pathway) over OXPHOS. Tumor cells balance ATP supply between glycolysis and OXPHOS. In some tumor cell lines, OXPHOS may still play a significant role in providing ATP, even though glycolysis is often the dominant pathway. The control of metabolic flux (the rate of a biochemical reaction) is distributed between glycolysis and OXPHOS in tumor cells where OXPHOS is more active. Understanding the control points of these pathways can be important for targeting them therapeutically. The passage discusses how drugs targeting glycolysis and mitochondrial function can impact tumor cell metabolism and cellular proliferation. This suggests that altering the metabolic pathways of tumor cells could be a potential strategy for cancer therapy. The energy metabolism may serve as an alternative therapeutic target for both glycolytic (hypoxic) and oxidative tumors. In other words, modulating the way tumor cells generate energy could be a viable strategy to modify their growth and response to treatment [4].

Histological characteristics and stage of tumor cells

The significant differences that exist between tumor cells and their nontransformed (normal) counterparts. These differences encompass genetic, biochemical, and histological aspects, and the passage particularly focuses on alterations in energy metabolism in fast-growing tumor cells. Tumor cells undergo substantial changes at the genetic, biochemical, and histological levels compared to the original non-transformed cells from which they originated. These changes are characteristic of cancer and contribute to the abnormal growth and behavior of tumor cells. That a majority of fast-growing tumor cell types exhibit a significantly altered energy metabolism compared to the tissue of origin. This metabolic shift is a well-documented phenomenon in various types of tumors. These include human tumors such as cervix (HeLa), pharynx, and mammary gland (MCF-7, MDA-MB-453) tumors, as well as astroblastomas, gliomas (U-251MG, D-54MG, U-87, and U118MG), and oligodendrogliomas. It also mentions tumors experimentally developed in rodents, such as hepatomas (Ehrlich, Ehrlich-Lettré, Morris, and AS-30D), Walker 256 carcinoma, and C6 glioma. The altered energy metabolism in cancer cells, often referred to as the Warburg effect or aerobic glycolysis, is a well-known characteristic of many cancer types. In this metabolic state, cancer cells preferentially use glycolysis (aerobic or anaerobic) to produce energy even in the presence of oxygen, rather than relying on the more efficient Oxidative Phosphorylation (OXPHOS) pathway, which is the primary energy production pathway in normal, non-cancerous cells [5,6].

Discussion

Tumor cells are characterized by having an elevated capacity for glycolysis, a metabolic pathway that converts glucose into energy even in the presence of abundant oxygen. This metabolic feature is a hallmark of many cancer cells. Accordingly, the dynamic focusing of growth cell contacts in the advancement of new and improvement of existing ways to deal with the treatment of strong cancers is one of the direst areas of current biomedicine. In tumor cells can be significantly higher than in normal, non-cancerous cells. For example, in rat hematomas, the glycolytic flux is reported to be 2 to 17 times higher than that of normal hepatocytes. It is suggested that this increase in glycolytic activity serves as a metabolic strategy for tumor cells. This strategy allows cancer cells to generate energy efficiently in environments with low oxygen concentrations, which are common within solid tumors. Understanding the increased glycolytic capacity in cancer cells, often referred to as the Warburg effect, is important in the context of cancer biology and therapy. This altered metabolism not only supports the high energy demands of rapidly dividing cancer cells but also leads to the accumulation of metabolic by-products, such as lactate, which can create a hostile microenvironment that promotes tumor progression.

Conclusion

Understanding the growth rate of tumors is important in research because it can provide insights into tumor biology, behaviour, and response to treatment. Fast-growing tumors are often more aggressive and may require different therapeutic approaches compared to slower-growing tumors. Researchers use these classifications to study the characteristics and behaviour of tumors in experimental settings, which can inform our understanding of cancer and the development of potential therapies. The complex relationship between energy metabolism and cancer, suggesting that targeting metabolic pathways in tumor cells may have therapeutic potential, especially in cases where oxidative phosphorylation remains active. This concept is an active area of research in the field of oncology and may lead to new strategies for cancer treatment in the future.

Acknowledgement

We thank the anonymous reviewers for their constructive criticisms of the manuscript. The support from ROMA (Research Optimization and recovery in the Manufacturing industry), of the Research Council of Norway is highly appreciated by the authors.

Conflict of Interest

None.

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