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The use of a novel and powerful technology that allows for the precise editing of the genetic material of various organisms is becoming widespread. This technology derives from bacterial and archaeal defense machinery and is called CRISPR Cas9. Unlike other gene editing tools that exclusively rely on proteins, CRISPR Cas9 utilizes interactions between the target DNA and an RNA sequence that guides the Cas9 enzyme to alter the structure of a target gene. Various genome locations can be edited thanks to the ease of programming different guide RNA sequences, facilitating its use and implementation. Furthermore, the non-active version of the Cas9 protein, guided by its corresponding RNA, can be utilized for visualization processes of genetic material or, more recently, for the regulation of the transcription process. Considering the recent advances and possibilities in biomedical and biotechnological research, we must understand that the exploration of this technology is just beginning, and its eventual applications will influence the world around us on multiple levels. In this review, we describe the biological foundations of the functioning of the Cas9 nuclease, together with selected applications of its use in editing and regulating specific sections of the genetic material of various organisms. We also discuss some bioethical issues surrounding this subject.

Introduction: Tumor budding (TB), defined as the presence of individual neoplastic cells or isolated groups of up to 4 cells at the front of tumor invasion, has become an adverse prognostic marker in colorectal cancer (CRC) in recent decades. The prognostic impact of TB in CRC remains not clearly defined and histological methods for its evaluation vary depending on the center. The objective of this study is to investigate the association between TB and CRC, in terms of oncological evolution and pathological stage., Methods: A retrospective observational study was conducted, including patients undergoing curative oncological surgery for CRC between January 2017 and December 2022. The effects of TB on disease-free survival (DFS) and overall survival (OS) were evaluated according to the Kaplan-Meier curves., Results: In 78 cases TB was described in the pathology report. TB was present in 56 patients (71.8%), divided into the following categories: low grade in 22 (39.3%), intermediate grade in 17 (30.4%) and high grade in 17 (30.4%). The proportion of patients who presented lymph node metastases, lympho-vascular and perineural invasion was significantly higher in patients with TB (26.8% vs 0%, P=.008; 41.1% vs 4.5%, P=.002; 16.1% vs 0% P=.054; respectively). DFS was 86.3% in low-grade TB, 75.3% in intermediate-grade TB, and 70.3% in high-grade TB. Cases with intermediate and high grade were associated with a shorter OS compared to the low grade group (93.7% and 75.4% vs 100% P=.012, respectively)., Conclusion: These results suggest that TB expression may be a useful risk factor as a prognostic factor for the detection of lymph node metastasis, local recurrence, and distant metastasis in CRC., (Copyright © 2024 The Author(s). Published by Elsevier España, S.L.U. All rights reserved.)