Novel Mutations of the PARP-1 Gene Associated with Colorectal Cancer in the Saudi Population PARP-1;colorectal cancer;DNA repair enzymes;single nucleotide polymorphism;Saudi Arabia; Background: colorectal cancer (CRC) is the third most common type of cancers and the fourth leading cause of death worldwide. In Saudi Arabia, CRC accounts for 8.5% of all tumors; it ranks first among all cancers in males and third among females. The aim of this study was to link between different PARP-1 mutations and risk of CRC in Saudi population and to determine common variants of PARP-1 in Saudi CRC patients and normal individuals. Materials and Methods: DNA samples were isolated from fifty CRC patients and from a comparable number of control subjects then sequenced to detect different variations present in exons 3, 17, and 21 of the PARP-1 gene. Results and Conclusions: When comparing the genotype and allele frequencies of all detected SNPs in CRC patients with those in controls, we found none were significantly different for all variants even the most common SNP in PARP-1 gene (Val762Ala). However, two novel alterations in exon 21 were found to be associated with increased risk of CRC. The variants identified as (1) Lys933Asn [p-value 0.0318] and (2) Lys945Asn [p-value 0.0257]. Our results suggest that PARP-1 Lys933Asn and Lys945Asn alterations could be associated with increased risk of CRC in the Saudi population.

Background/Objectives: The renin–angiotensin system (RAS) is well-established as a moderator of cardiovascular equilibrium and blood pressure. Nevertheless, growing evidence indicates that angiotensin II (Ang II), the principal RAS effector peptide, together with additional constituents, is involved in various malignancies. Since the immune system is an important aspect in tumor development, this study sought to investigate the role of Ang II in the crosstalk between tumor-associated macrophages (TAMs) and breast cancer cells in the tumor microenvironment (TME). Methods: We treated THP-1-like macrophages with 100 nM Ang II for 24 h. The culture media thus obtained was used as conditioned media and applied at 50% on MCF-7 and MDA-MB-231 breast cancer cell lines. The effects of the conditioned media on cancer cell lines were then investigated by various methods such as a cell proliferation assay, migration assay, polarization assay, and by the detection of apoptosis and reactive oxygen species (ROS) generation. Results: We demonstrated that in vitro Ang II promotes macrophage polarization toward proinflammatory M1-like macrophages and anti-inflammatory M2-like macrophages. Interestingly, Ang II, through macrophages, showed varied effects on different breast cancer cell lines, promoting tumor growth and progression in MCF-7 while inhibiting tumor growth and progression in MDA-MB-23. Conclusions: This study has provided clear evidence that Ang II in the TME modulates TAM polarization and secretions, leading to different effects based on the type of breast cancer.

Background: Fluid shear stress (FSS) is a biomechanical force that can produce phenotypic changes in the cells that are directly in contact with the flow of fluid. Accumulating evidence indicates high FSS to possess the potential ability to prevent tumor development and suppress cancer growth. However, the exact mechanism of its antitumorigenic effects is still not clear. Objective: In this study, we aimed to investigate the effect of FSS on breast cancer microenvironment via macrophage modulation. Methods: We exposed THP-1 like-macrophages to different levels of FSS. The supernatant from THP1-like-macrophages after exposure to FSS was used as conditioned medium (FSS-CM). Subsequently, we analyzed human breast cancer cells, MCF-7, and endothelial cells, as well as HUVECs cultured with FSS-CM. Results: Study outcomes have demonstrated that low FSS-CM inhibited apoptosis as well as induced tumor migration in MCF-7 cells. Conversely, high FSS-CM promoted apoptosis, inhibited tumor migration, and induced G1-phase arrest in MCF-7 cells. Furthermore, low FSS-CM was found to promote proliferation of HUVECs. Conclusions: In conclusion, this study highlights the complex interplay between FSS and cancer cell behavior. Our findings provide in vitro evidence that high FSS exerts an anti-cancer effect by promoting THP-1-like macrophage polarization toward an anti-tumor phenotype, leading to increased apoptosis and reduced migration in MCF-7 cells. These results suggest that the modulation of macrophage polarization may underlie the therapeutic potential of high FSS in suppressing breast cancer progression.