Combined regimens of cisplatin and metformin in cancer therapy: A systematic review and meta-analysis

Fisetin enhances cisplatin sensitivity in renal cell carcinoma via the CDK6/PI3K/Akt/mTOR signaling pathway

Cisplatin resistance is ubiquitous among patients with renal cell carcinoma (RCC). The present study assessed the role of fisetin in regulating cisplatin sensitivity and increasing the efficacy of chemotherapy for patients with RCC. Cell Counting Kit-8 and colony formation assays were used to assess the proliferation of RCC cells after fisetin and cisplatin treatment. The mRNA expression levels of cyclin-dependent kinase (CDK)6 were evaluated using reverse transcription-quantitative PCR. The expression levels of CDK6 and key proteins of the PI3K/Akt/mTOR signaling pathway were assessed using western blotting. The present study demonstrated that fisetin inhibited the proliferation and colony-forming ability of RCC cells, and induced apoptosis and cell cycle arrest in a dose-dependent manner. Additionally, fisetin enhanced the antineoplastic effects of cisplatin, as demonstrated by the increase in proliferation inhibition and apoptosis promotion after fisetin and cisplatin combination treatment. Furthermore, fisetin regulated the PI3K/Akt/mTOR signaling pathway through CDK6 inhibition, which enhanced cisplatin sensitivity. Overexpression of CDK6 neutralized the positive effects of fisetin on the improvement of cisplatin sensitivity in RCC cells. In conclusion, fisetin may enhance the sensitivity of RCC cells to cisplatin via the CDK6/PI3K/Akt/mTOR signaling pathway.

Exploring the Synergistic Effect of Sildenafil and Green Tea Polyphenols on Breast Cancer Stem Cell-like Cells and their Parental Cells: A Potential Novel Therapeutic Approach

BACKGROUND

Many cancer studies have intensely focused on the role of diet, among other factors involved in cancer establishment. The positive effect of green tea polyphenols (GTP) on controlling breast cancer cells has been reported in several studies. Cancer stem cell-like cells (CSC-LCs) possessing self-renewal, metastatic, and drug-resistant capacities are considered prominent therapeutic targets. In many tumors, inducible nitric oxide synthase (iNOS) expression levels are high; however, they have a dual effect on breast cancer pathogenesis.

OBJECTIVE

This study aimed to investigate the cytotoxicity of the iNOS agonist (Sildenafil) and antagonist (LNAME), both alone and in combination with GTP, on MDA-MB-231, CD44+/CD24- CSC-LCs, and their parental cells (MCF-7).

METHODS

The cell viability assay has been studied using the MTT assay. To analyze drug-drug combinations, CompuSyn and Combenefit software were used. The cytotoxicity mechanism was determined using flow cytometric analysis.

RESULTS

L-NAME and GTP showed a synergistic effect on MDA-MB-231 and CSC-LCs. Such an effect was not observed on MCF-7. Sildenafil and GTP, on the other hand, showed synergistic cytotoxicity in all the cells mentioned above. Flow cytometric tests resulted in more than 70% apoptosis in MDA-MB-231 and MCF-7. Also, sub-G1 arrest among MCF-7 cells and a considerable decrease in ROS production by MDA-MB-231 cells following treatment with Sildenafil and GTP were observed.

CONCLUSION

Sildenafil, in combination with flavonoids, may be considered a novel strategy for cancer treatment.

Resveratrol as an antitumor agent for glioblastoma multiforme: Targeting resistance and promoting apoptotic cell deaths

Glioblastoma multiforme (GBM) is one of the most aggressive brain and spinal cord tumors. Despite the significant development in application of antitumor drugs, no significant increases have been observed in the survival rates of patients with GBM, as GBM cells acquire resistance to conventional anticancer therapeutic agents. Multiple studies have revealed that PI3K/Akt, MAPK, Nanog, STAT 3, and Wnt signaling pathways are involved in GBM progression and invasion. Besides, biological processes such as anti-apoptosis, autophagy, angiogenesis, and stemness promote GBM malignancy. Resveratrol (RESV) is a non-flavonoid polyphenol with high antitumor activity, the potential of which, regulating signaling pathways involved in cancer malignancy, have been demonstrated by many studies. Herein, we present the potential of RESV in both single and combination therapy- targeting various signaling pathways- which induce apoptotic cell death, re-sensitize cancer cells to radiotherapy, and induce chemo-sensitizing effects to eventually inhibit GBM progression.

Disparities in Cisplatin-Induced Cytotoxicity-A Meta-Analysis of Selected Cancer Cell Lines

Cisplatin is a classic anticancer drug widely used as a reference drug to test new metal complex drug candidates. We found an unexpected diversity in cisplatin-related cytotoxicity values, expressed as IC50 (the half-maximal inhibitory concentration) in tumour cell lines, such as MCF-7, HepG2 and HeLa. We reviewed the data published from 2018 to 2022. A total of 41 articles based on 56 in vitro experiments met our eligibility criteria. Using a meta-analysis based on a random effect model, we evaluated the cytotoxicity of cisplatin (IC50) after 48- or 72-h cell exposure. We found large differences between studies using a particular cell line. According to the random effect model, the 95% confidence intervals for IC50 were extremely wide. The heterogeneity of cisplatin IC50, as measured by the I2 index for all cancer cell lines, was over 99.7% at culture times of 48 or 72 h. Therefore, the variability between studies is due to experimental heterogeneity rather than chance. Despite the higher IC50 values after 48 h than after 72 h, the heterogeneity between the two culture periods did not differ significantly. This indicates that the duration of cultivation is not the main cause of heterogeneity. Therefore, the available data is diverse and not useful as a reference. We discuss possible reasons for the IC50 heterogeneity and advise researchers to conduct preliminary testing before starting experiments and not to solely rely on the published data. We hope that this systematic meta-analysis will provide valuable information for researchers searching for new cancer drugs using cisplatin as a reference drug.

Drug Repurposing in Oncology: A Systematic Review of Randomized Controlled Clinical Trials

Quality pharmacological treatment can improve survival in many types of cancer. Drug repurposing offers advantages in comparison with traditional drug development procedures, reducing time and risk. This systematic review identified the most recent randomized controlled clinical trials that focus on drug repurposing in oncology. We found that only a few clinical trials were placebo-controlled or standard-of-care-alone-controlled. Metformin has been studied for potential use in various types of cancer, including prostate, lung, and pancreatic cancer. Other studies assessed the possible use of the antiparasitic agent mebendazole in colorectal cancer and of propranolol in multiple myeloma or, when combined with etodolac, in breast cancer. We were able to identify trials that study the potential use of known antineoplastics in other non-oncological conditions, such as imatinib for severe coronavirus disease in 2019 or a study protocol aiming to assess the possible repurposing of leuprolide for Alzheimer's disease. Major limitations of these clinical trials were the small sample size, the high clinical heterogeneity of the participants regarding the stage of the neoplastic disease, and the lack of accounting for multimorbidity and other baseline clinical characteristics. Drug repurposing possibilities in oncology must be carefully examined with well-designed trials, considering factors that could influence prognosis.

Immunoregulation by resveratrol; implications for normal tissue protection and tumour suppression

Immune reactions are involved in both tumour and normal tissue in response to therapy. Elevated secretion of certain chemokines, exosomes and cytokines triggers inflammation, pain, fibrosis and ulceration among other normal tissue side effects. On the other hand, secretion of tumour-promoting molecules suppresses activity of anticancer immune cells and facilitates the proliferation of malignant cells. Novel anticancer drugs such as immune checkpoint inhibitors (ICIs) boost anticancer immunity via inducing the proliferation of anticancer cells such as natural killer (NK) cells and CD8+ T lymphocytes. Certain chemotherapy drugs and radiotherapy may induce anticancer immunity in the tumour, however, both have severe side effects for normal tissues through stimulation of several immune responses. Thus, administration of natural products with low side effects may be a promising approach to modulate the immune system in both tumour and normal organs. Resveratrol is a well-known phenol with diverse effects on normal tissues and tumours. To date, a large number of experiments have confirmed the potential of resveratrol as an anticancer adjuvant. This review focuses on ensuing stimulation or suppression of immune responses in both tumour and normal tissue after radiotherapy or anticancer drugs. Later on, the immunoregulatory effects of resveratrol in both tumour and normal tissue following exposure to anticancer agents will be discussed.

Mechanisms of cancer cell death induction by paclitaxel: an updated review

Chemoresistance of cancer cells is a major problem in treating cancer. Knowledge of how cancer cells may die or resist cancer drugs is critical to providing certain strategies to overcome tumour resistance to treatment. Paclitaxel is known as a chemotherapy drug that can suppress the proliferation of cancer cells by inducing cell cycle arrest and induction of mitotic catastrophe. However, today, it is well known that paclitaxel can induce multiple kinds of cell death in cancers. Besides the induction of mitotic catastrophe that occurs during mitosis, paclitaxel has been shown to induce the expression of several pro-apoptosis mediators. It also can modulate the activity of anti-apoptosis mediators. However, certain cell-killing mechanisms such as senescence and autophagy can increase resistance to paclitaxel. This review focuses on the mechanisms of cell death, including apoptosis, mitotic catastrophe, senescence, autophagic cell death, pyroptosis, etc., following paclitaxel treatment. In addition, mechanisms of resistance to cell death due to exposure to paclitaxel and the use of combinations to overcome drug resistance will be discussed.