Targeting Mutated p53 Dependency in Triple-Negative Breast Cancer Cells Through CDK7 Inhibition

Abstract

BackgroundCyclin-dependent kinase 7 (CDK7) is crucial for cell cycle progression and gene expression transcriptional regulation, which are often not assessed in cancer developing process. CDK7 inhibitors have emerged as promising drugs for treating diverse cancers, including breast cancer. However, the mechanism behind its anticancer effect has not been well investigated. Here, the possible mechanism of CDK7 inhibitors for treating human triple-negative breast cancer (TNBC) has been studied.MethodsThe effects of CDK7 inhibitors on breast cancer cells have been identified by measuring cell viability (Cell Counting Kit-8) and cell proliferation and calculating colony formation. The short hairpin RNA and short interfering RNA were used for the construction of knockdown cells. To assess the expression of associated proteins, western blot was used.ResultsThis study confirmed that, compared to hormone receptor-positive breast cancer cells, TNBC cells were more sensitive to THZ1, a novel CDK7 inhibitor. THZ1 treatment specifically downregulated mutated p53 in a dose- and time-dependent manner in TNBC cells with p53 mutation. Another CDK7 inhibitor, LDC4297, also potently interfered with the expression of mutated p53. Furthermore, endogenous CDK7 expression was positively correlated with the levels of mutated p53 in TNBC cells with p53 mutation. Downregulating mutated p53 expression significantly suppressed the proliferation of TNBC cells with p53 mutation.ConclusionOur findings demonstrated that targeting CDK7 was an effective approach for the treatment of TNBC with p53 mutation.

p53–GSDME Elevation: A Path for CDK7 Inhibition to Suppress Breast Cancer Cell Survival

“…As shown in Figures 2A,B , the group with CDK7 shRNA vectors displayed decreased cell proliferation and fewer colony spots than the control group. In our exploration of the regulatory mechanism, expression levels of p53, a downstream effector of CDK7 ( Figures 2C,D ), indicated that CDK7 inhibition increased the p53 protein levels, confirming previous results ( Peng et al, 2021 ).…”

“…To explore the effect of CDK7 inhibitors on breast cancer cells, we measured the viability of MCF-7 cells after incubation with increasing concentrations of THZ1 and LDC4297 for 24 and 48 h. The CCK8 results showed that although the survival of MCF-7 cells was not significantly affected by treatment with low concentrations of THZ1, the repressive effect could still be detected in a dose- and time-dependent manner, confirming previous results ( Peng et al, 2021 ). As shown in Figure 1A , LDC4297 also suppressed tumor growth.…”

“…The packaged viral vectors were added into the culture medium of 293T cells, and after 48 h, the supernatant of the 293T cells was collected and purified through 0.45 µm membranes. Lentiviral transfection was performed as previously reported ( Peng et al, 2021 ), to downregulate the expression of related proteins in breast cancer cells. The effect of shRNA was assessed using western blotting.…”

Targeting the Heterogeneous Genomic Landscape in Triple-Negative Breast Cancer through Inhibitors of the Transcriptional Machinery

“…This combination therapy is therefore not effective in p53-deficient cells. Moreover, CDK7 inhibition also reduced the expression of mutant p53 in TNBC cells, while upregulating WT p53 in ER+ breast cancer cells, although the exact mechanism underlying this potential selectivity remains elusive [ 103 ]. Similar to interactions with p53 and BRD4, CDK8 binds to p53 target genes and is a co-activator of the p53 transcriptional program in response to p53-activating stimuli [ 104 ].…”

Elevation of effective p53 expression sensitizes wild-type p53 breast cancer cells to CDK7 inhibitor THZ1

“…Although THZ1 has been demonstrated to suppress triple-negative breast cancer (TNBC), its anticancer effect on non-TNBC breast cancer cells, including MCF-7 and ZR-75-1 cells, is still controversial [ 12 , 13 ]. We previously reported that a low THZ1 concentration mainly repressed MCF-7 cell proliferation rather than induced cell death [ 14 , 15 ]. Therefore, strategies that decrease the survival and trigger the death of wild-type (WT) p53 breast cancer cells at low THZ1 concentrations might contribute to breast cancer therapy.…”