Small molecule induction of MSH2-dependent cell death suggests a vital role of mismatch repair proteins in cell death

Abstract

Avoidance of apoptosis is one of the hallmarks of cancer development and progression. Chemotherapeutic agents aim to initiate an apoptotic response, but often fail due to dysregulation. MSH proteins are capable of recognizing cisplatin damage in DNA and participate in the initiation of cell death. We have exploited this recognition and computationally simulated a MutS homolog (MSH) “death conformation”. Screening and docking experiments based on this model determined that the MSH2-dependent cell-death pathway can be induced by a small molecule without DNA damage, reserpine. Reserpine was identified via virtual screening on structures obtained from molecular dynamics as a small molecule that selectively binds a protein “death” conformation. The virtual screening predicts that this small molecule binds in the absence of DNA. Cell biology confirmed that reserpine triggers the MSH2-dependent cell death pathway. This result supports the hypothesis that the MSH2-dependent pathway is initiated by specific protein conformational changes triggered by binding to either DNA damage or small compound molecules. These findings have multiple implications for drug discovery and cell biology. Computational modeling may be used to identify and eventually design small molecules that selectively activate particular pathways through conformational control. Molecular dynamics simulations can be used to model the biologically-relevant conformations and virtual screening can then be used to select for small molecules that bind specific conformations. The ability of a small molecule to induce the cell death pathway suggests a broader role for MMR proteins in cellular events, such as cell death pathways, than previously suspected.

Non-specificity and synergy at the binding site of the carboplatin-induced DNA adduct via molecular dynamics simulations of the MutSα–DNA recognition complex

“…A computational study of MutSα (Salsbury Jr et al, 2006) bound to the same adduct agrees with these latter more modest conformational changes found by X-ray and AFM studies. The key interactions found in this paper were indirectly confirmed via mutagenesis analysis combined with cellular assays for repair function and cell death (Salsbury Jr et al, 2006; Vasilyeva et al, 2009). …”

“…This damage eventually induces cell death. The exact mechanism by which cell death is induced is not fully understood (Jamieson & Lippard, 1999; Wang & Lippard, 2005; Vasilyeva et al, 2009). One hypothesis is that cell death is induced by the recognition of these platinum-DNA adducts by several specific cellular proteins(Andrews & Howell, 1990; Kartalou & Essigmann, 2001).…”

“…In addition to the DNA repair function, MutSα detects and provokes cell death in response to certain types of DNA damage, including the lesions produced by chemotherapeutic agents cisplatin and carboplatin (Duckett et al, 1996; Fink et al, 1996; Mello, Acharya, Fishel, & Essigmann, 1996; Salsbury Jr et al, 2006; Vasilyeva et al, 2009). Many details remain to be elucidated in precisely how cell death is induced, although it has been shown that apoptosis is the ultimate cellular endpoint (Young et al, 2003; Drotschmann, Topping, Clodfelter, & Salsbury Jr, 2004; Salsbury Jr et al, 2006; Vasilyeva et al, 2009).…”

Targeted Approach to Overcoming Treatment Resistance in Advanced Prostate Cancer

“…3 compares the effect of rescinnamine on RWPE and LnCAP cells, with A2780 cells added as a control. Overall, the effect of rescinnamine on prostate cancer cells is much weaker than what we previously observed with other cell lines (Vasilyeva et al, 2009).…”

“…Molecular docking experiments were performed as follows: The molecular docking was performed in four phases; structural model generation, ligand library generation, receptor grid generation and finally docking of the ligand library into the receptor grid. Models for the structures were generated using molecular dynamics as in our previous works (Vasilyeva, A et al, 2009;Vasilyeva, A et al, 2010;Salsbury. 2010).…”