Mechanisms of Senescence in Cancer: Positive and Negative Aspects of Cancer Cells Senescence.

Cell senescence was considered an attribute of normal dividing cells, which distinguishing them from cancer cells that do not have a division limit. However, recent studies show that senescence could also occur in cancer cells. Cancer cell senescence could occur as a result of chemotherapy, radiation, inhibition of telomerase activity, induction of DNA damage, changes in the tumor microenvironment, regulation of senescence-related proteins, oxidative stress, inflammation, or epigenetic dysregulation. It seems that the induction of senescence in cancer cells could significantly affect the inhibition of tumor progression, but in some types of cancer, it can affect their invasive character. Furthermore, considering the therapeutic implications of this process, it is essential to consider the positive and negative aspects of cancer cell senescence. It is crucial to understand the molecular mechanisms that induce senescence under specific conditions, considering the potential hazards. In the future, the senescence of cancer cells may contribute to using this property in modern cancer treatment strategies.

Natural Radiosensitizers in Radiotherapy: Cancer Treatment by Combining Ionizing Radiation with Resveratrol.

Conventional cancer treatment is mainly based on the surgical removal of the tumor followed by radiotherapy and/or chemotherapy. When surgical removal is not possible, radiotherapy and, less often, chemotherapy is the only way to treat patients. However, despite significant progress in understanding the molecular mechanisms of carcinogenesis and developments in modern radiotherapy techniques, radiotherapy (alone or in combination) does not always guarantee treatment success. One of the main causes is the radioresistance of cancer cells. Increasing the radiosensitivity of cancer cells improves the processes leading to their elimination during radiotherapy and prolonging the survival of cancer patients. In order to enhance the effect of radiotherapy in the treatment of radioresistant neoplasms, radiosensitizers are used. In clinical practice, synthetic radiosensitizers are commonly applied, but scientists have recently focused on using natural products (phytocompounds) as adjuvants in radiotherapy. In this review article, we only discuss naturally occurring radiosensitizers currently in clinical trials (paclitaxel, curcumin, genistein, and papaverine) and those whose radiation sensitizing effects, such as resveratrol, have been repeatedly confirmed by many independent studies.