Structural and Biochemical Basis of Etoposide-Resistant Mutations in Topoisomerase IIα

Etoposide is a widely used anticancer drug that targets type II topoisomerases, including topoisomerase IIα (TOP2A). TOP2A is a nuclear enzyme involved in regulating DNA topology through a double-strand passage mechanism. TOP2A is a homodimeric enzyme with two symmetrical active sites formed by residues from either half of the dimer. Both active sites cleave DNA, forming an enzyme-bound, double-stranded DNA break. Etoposide acts by binding in the active site between the ends of cleaved DNA, preventing the enzyme from ligating the DNA. In the present study, biochemical and structural data are used to examine the mechanism of etoposide resistance found with specific point mutations in TOP2A. Mutations near the active site (D463A, G534R, R487K), along with some outside of the active site (ΔA429 and P716L), are examined. We hypothesize that changes in the coordination of DNA cleavage results from mutations that impact symmetrical relationships in the active site and surrounding regions. In some cases, we report the first data on purified versions of these enzymes. Based upon our results, both local and long-distance factors can impact etoposide action and may indicate interdependent relationships in structure and function

Structural and Biochemical Basis of Etoposide-Resistant Mutations in Topoisomerase IIα

Etoposide is a widely used anticancer drug that targets type II topoisomerases, including topoisomerase IIα (TOP2A). TOP2A is a nuclear enzyme involved in regulating DNA topology through a double-strand passage mechanism. TOP2A is a homodimeric enzyme with two symmetrical active sites formed by residues from either half of the dimer. Both active sites cleave DNA, forming an enzyme-bound, double-stranded DNA break. Etoposide acts by binding in the active site between the ends of cleaved DNA, preventing the enzyme from ligating the DNA. In the present study, biochemical and structural data are used to examine the mechanism of etoposide resistance found with specific point mutations in TOP2A. Mutations near the active site (D463A, G534R, R487K), along with some outside of the active site (ΔA429 and P716L), are examined. We hypothesize that changes in the coordination of DNA cleavage results from mutations that impact symmetrical relationships in the active site and surrounding regions. In some cases, we report the first data on purified versions of these enzymes. Based upon our results, both local and long-distance factors can impact etoposide action and may indicate interdependent relationships in structure and function

Measuring Pharmacy Student Attitudes Toward Prayer: The Student Prayer Attitude Scale (SPAS)

The objective of this study was to develop and validate an instrument to assess the attitude of student pharmacists toward prayer in general and in particular as it relates to their academic performance. To fulfill the study objective, faculty from seven colleges of pharmacy located at Christian universities collaboratively developed the Student Prayer Attitude Scale (SPAS). The items were used to assess the attitudes of student pharmacists toward prayer as well as the effects of prayer on personal lives and academic performance. Faculty investigators asked 1,563 students to complete the survey and received 677 valid responses. A principal components analysis with promax rotation was conducted and revealed a two-factor structure: (a) general attitude toward prayer and (b) specific attitude regarding the impact of prayer on academic performance. Analysis of variance was used to compare student responses by religious identity. Students identifying as atheist or agnostic were significantly different in their responses than students from theistic religions; however, the responses of students from various theistic religions were not significantly different from one another. Faculty concluded that SPAS is a reliable tool for measuring student attitudes toward prayer. The use of such a tool could help faculty tailor educational opportunities to allow pharmacy students to explore prayer more fully and be aware of its impact on the patients they serve