Resensitization of cisplatin resistance ovarian cancer cells to cisplatin through pretreatment with low-dose fraction radiation

A peptide-salinomycin conjugate with a bystander effect reduces the stemness characteristics of ovarian cancer cells and enhances drug sensitivity

Salinomycin (Sal) has attracted considerable attention in the field of tumor treatment, especially for its inhibitory effect on cancer stem cells (CSCs) and drug-resistant tumor cells. However, its solubility and targeting specificity pose significant challenges to its pharmaceutical development. Sal-A6, a novel peptide-drug conjugate (PDC), was formed by linking the peptide A6 targeting the CSC marker CD44 with Sal using a specific linker. This conjugation markedly enhances the physicochemical properties of Sal and compared to Sal, Sal-A6 demonstrated a significantly increased activity against ovarian cancer. Furthermore, Sal-A6, employing a disulfide bond as a linker, exhibited bystander killing effect. Moreover, it induces substantial cytotoxic effect on both cancer stem cells and drug-resistant cells in addition to enhance chemosensitivity of resistant ovarian cancer cells. In summary, the results indicated that Sal-A6, a novel PDC derived from Sal, has potential therapeutic applications in the treatment of ovarian cancer and drug-resistant patients. Additionally, this discovery offers insights for developing PDC-type drugs using Sal as a foundation.

Cisplatin in Ovarian Cancer Treatment-Known Limitations in Therapy Force New Solutions

Cisplatin is one of the most commonly used anticancer drugs worldwide. It is mainly used in the treatment of ovarian cancer, but also used in testicular, bladder and lung cancers. The significant advantage of this drug is the multidirectional mechanism of its anticancer action, with the most important direction being damaging the DNA of cancer cells. Unfortunately, cisplatin displays a number of serious disadvantages, including toxicity to the most important organs, such as kidneys, heart, liver and inner ear. Moreover, a significant problem among patients with ovarian cancer, treated with cisplatin, is the development of numerous resistance mechanisms during therapy, including changes in the processes of cellular drug import and export, changes in the DNA damage repair mechanisms, as well as numerous changes in the processes of apoptosis and autophagy. Due to all of the mentioned problems, strategies to increase the effectiveness of cisplatin in the treatment of ovarian cancer are intensively sought. The most important strategy includes the development of less toxic cisplatin analogs. Another important direction is combination therapy, involving the simultaneous use of cisplatin with different anticancer drugs, substances derived from plants, temperature or radiotherapy. Many years of observations accompanying the presence of cisplatin in the therapy made it possible to provide a series of verifiable, statistically significant data, but also to show how, over time, with the new information and scientific discoveries, it is possible to describe and understand the therapeutic problems observed in practice, such as the acquisition of drug resistance by tumor cells or induction of changes in the tumor microenvironment. According to the authors, confronting what we knew so far with what new trends offer has a profound meaning. This paper presents information on the history of cisplatin and describes the molecular mechanisms of its action and the development of resistance by cancer cells. In addition, our goal was to highlight a number of therapeutic strategies to increase the effectiveness of cisplatin in the treatment of ovarian cancer, as well as to identify methods to eliminate problems associated with the use of cisplatin.

Apoptosis Induction with Combined Use of Cisplatin and Fisetin in Cisplatin-Resistant Ovarian Cancer Cells (A2780)

BACKGROUND

Ovarian cancer is the leading cause of death caused by genital cancers. One of the most common treatments for this type of cancer is chemotherapy by cisplatin, which induces apoptosis in cancer cells. Apoptosis is a type of physiological cell death. Cisplatin chemotherapy usually has several side effects and cellular resistance to cisplatin is a common incidence. In order to overcome these problems, the use of combination therapies using natural substances has been considered. Fisetin is a flavonoid with anti-cancer activity which induces apoptosis. In this study, the apoptosis induced by cisplatin along with Fisetin in cisplatin-resistant ovarian cancer cell line (A2780) was investigated.

METHODS

In the present experimental study, the effect of combined use of Fisetin and cisplatin on ovarian cancer cell lines (A2780) was investigated by using MTT assay. Cell death was also determined by DAPI, acridine orange/propidium iodide, and Annexin/PI assay. Apoptotic gene expression of Bax, BCL-2, caspase 3, and caspase 9 was also assessed by real time PCR.

RESULTS

The results of MTT assay indicated that the combined treatment of Fisetin and cisplatin effectively inhibits proliferation of A2780 cells. The results of DAPI staining showed that fragmentation of chromatin in cells occurred in the combined treatment. Acridine orange-propidium iodide staining and Annexin/PI staining showed an increase in the rate of apoptotic cells in cells under combined treatment. The results of the study regarding changes in gene expression also indicated that Bax pro-apoptotic gene expression and BCL-2 anti-apoptotic gene expression increased in cells under treatment; moreover, gene expression of caspases 3 and 9 significantly increased as well.

CONCLUSION

According to the findings of this study, the combined use of cisplatin and Fisetin increases the induction of apoptosis in cisplatin-resistant ovarian cancer cells (A2780); therefore, the combined use of cisplatin and Fisetin can be considered a promising strategy in the treatment of ovarian cancer.

Resensitization of cisplatin resistance ovarian cancer cells to cisplatin through pretreatment with low-dose fraction radiation

Objective

Cisplatin is the first‐line chemotherapy for ovarian cancer. However, cisplatin resistance is severely affecting the treatment efficacy. FOXO3a has been reported to be involved in reversing chemotherapy resistance. However, whether low‐dose fraction radiation therapy (LDFRT) can reverse cisplatin resistance remains unclear. This study aimed to explore the effect of LDFRT on cisplatin resistance and its relation with FOXO3a expression in vitro.

Methods

The toxicity of cisplatin on SKOV3/DDP cells was evaluated by CCK8 assay and cell apoptosis was measured by Annexin V‐FITC staining as well as Hoechst33342 staining. The expression of FOXO3a and other relative proteins was measured by western blot.

Results

Our study found that LDFRT enhanced cisplatin‐induced apoptosis of SKOV3/DDP cells and promoted the expression of FOXO3a and pro‐apoptotic protein PUMA. In addition, overexpression of FOXO3a promoted PUMA activity and toxicity of cisplatin on SKOV3/DDP cells.

Conclusion

LDFRT reverses cisplatin resistance of SKOV3/DDP cells possibly by upregulating the expression of FOXO3a and its downstream target PUMA, suggesting that LDFRT might be a potent chemosensitizer for the treatment of ovarian cancer.