p53 reactivating small molecule PRIMA‑1MET/APR‑246 regulates genomic instability in MDA‑MB‑231 cells

ASAH1 facilitates TNBC by DUSP5 suppression-driven activation of MAP kinase pathway and represents a therapeutic vulnerability

Triple-negative breast cancer (TNBC) is a subtype of breast cancer that is prone to metastasis and therapy resistance. Owing to its aggressive nature and limited availability of targeted therapies, TNBC is associated with higher mortality as compared to other forms of breast cancer. In order to develop new therapeutic options for TNBC, we characterized the factors involved in TNBC growth and progression. Here, we demonstrate that N-acylsphingosine amidohydrolase 1 (ASAH1) is overexpressed in TNBC cells and is regulated via p53 and PI3K-AKT signaling pathways. Genetic knockdown or pharmacological inhibition of ASAH1 suppresses TNBC growth and progression. Mechanistically, ASAH1 inhibition stimulates dual-specificity phosphatase 5 (DUSP5) expression, suppressing the mitogen-activated protein kinase (MAPK) pathway. Furthermore, pharmacological cotargeting of the ASAH1 and MAPK pathways inhibits TNBC growth. Collectively, we unmasked a novel role of ASAH1 in driving TNBC and identified dual targeting of the ASAH1 and MAPK pathways as a potential new therapeutic approach for TNBC treatment.

PRIMA-1MET Does Not Restore Vitamin D Sensitivity to MDA-MB-231 and MDA-MB-468 Triple-Negative Breast Cancer Cells

Vitamin D is a steroid hormone that causes growth suppression in cultured cells. We had previously discovered that the triple-negative breast cancer cell lines MDA-MB-231 and MDA-MB-468 did not have growth suppression with vitamin D, while MCF-7 did. MCF-7 cells are not triple-negative and have wild-type p53. Both MDA-MB-231 and MDA-MB-468 have mutations in p53 and these mutations were a possible explanation for the lack of growth suppression with vitamin D. Our hypothesis was that reactivation of p53 in the triple-negative cell lines would cause them to become sensitive to vitamin D. We chose to use the small molecule PRIMA-1MET to reactivate p53 as it has been previously shown to restore function to the p53 mutants present in MB-231 and MB-468. We then measured the ability of vitamin D and its analogues calcipotriol and EB1089 to suppress growth in the presence of PRIMA-1MET. Here, we show that while PRIMA-1MET can kill the breast cancer cells investigated in this study, it does not restore their sensitivity to vitamin D or its analogues.

Dysregulation of P53 in breast cancer: Causative factors and treatment strategies

One of the most prevalent cancers impacting women worldwide is breast cancer. Although there are several risk factors for breast cancer, the p53 gene's function has recently received much attention. The "gatekeeper" gene, or p53, is sometimes referred to as such since it is crucial in controlling cell proliferation and preventing the development of malignant cells. By identifying DNA damage and initiating cellular repair processes, p53 usually functions as a tumor-suppressor. But p53 gene alterations can result in a lack of function, allowing cells to divide out of control and perhaps triggering the onset of cancer. Various factors, such as mutation genes, signaling pathways, and hormones, can dysregulate P53 proteins and cause breast cancer. A promising strategy for individualized cancer treatment involves focusing on p53 mutations in breast cancer. While numerous techniques, including gene therapy and small compounds, have shown promise, further study is required to create safe and efficient treatments to target p53 mutations in breast cancer successfully.

p53/MicroRNA-34 axis in cancer and beyond

Cancer is serious endangers human life. After a long period of research and accumulation, people's understanding of cancer and the corresponding treatment methods are constantly developing. p53 is an important tumor suppressor gene. With the more in-depth understanding of the structure and function of p53, the more importance of this tumor suppressor gene is realized in the process of inhibiting tumor formation. MicroRNAs (miRNAs) are important regulatory molecules with a length of about 22nucleotides (nt), which belong to non-coding RNA and play an important role in the occurrence and development of tumors. miR-34 is currently considered to be a master regulator of tumor suppression. The positive feedback regulatory network formed by p53 and miR-34 can inhibit the growth and metastasis of tumor cells and inhibit tumor stem cells. This review focuses on the latest progress of p53/miR-34 regulatory network, and discusses its application in tumor diagnosis and treatment.

Targeting Homologous Recombination Deficiency in Ovarian Cancer with PARP Inhibitors: Synthetic Lethal Strategies That Impact Overall Survival

Simple Summary

Synthetic lethality approaches to cancer therapy involves combining events to cause cancer cell death. Using this strategy, major advances have occurred in the treatment of women with ovarian cancer who have defects in the Homologous Recombination Repair (HRR) pathway. When the HRR pathway is defective, due to mutations or epigenetic changes in genes such as BRCA1 or BRCA2, cells can no longer accurately repair double strand breaks (DSBs). Capitalising on this weakness, pharmacological inhibition of poly (ADP-ribose) polymerase (PARP) that function to repair single strand breaks (SSBs) leads to synthetic lethality in cells with defective HRR. PARP inhibitors (PARPis) including olaparib, niraparib and rucaparib are approved for the clinical management of women with ovarian cancer. Understanding and overcoming issues of acquired resistance to PARPis, extending these strategies to benefit more patients and combining PARPis with other drugs, including immunotherapies, are of high priority in the field today.

Abstract

The advent of molecular targeted therapies has made a significant impact on survival of women with ovarian cancer who have defects in homologous recombination repair (HRR). High-grade serous ovarian cancer (HGSOC) is the most common histological subtype of ovarian cancer, with over 50% displaying defective HRR. Poly ADP ribose polymerases (PARPs) are a family of enzymes that catalyse the transfer of ADP-ribose to target proteins, functioning in fundamental cellular processes including transcription, chromatin remodelling and DNA repair. In cells with deficient HRR, PARP inhibitors (PARPis) cause synthetic lethality leading to cell death. Despite the major advances that PARPis have heralded for women with ovarian cancer, questions and challenges remain, including: can the benefits of PARPis be brought to a wider range of women with ovarian cancer; can other drugs in clinical use function in a similar way or with greater efficacy than currently clinically approved PARPis; what can we learn from long-term responders to PARPis; can PARPis sensitise ovarian cancer cells to immunotherapy; and can synthetic lethal strategies be employed more broadly to develop new therapies for women with ovarian cancer. We examine these, and other, questions with focus on improving outcomes for women with ovarian cancer.