Mohammed H. Almuhanna

Colorectal cancer prognosis get worse with advancement of disease into metastatic stage. There is a pertinent need to develop prognostic biomarkers that can be used for personalized and precision medicine. Alternative splicing provides an insight into understanding of changes at isoform expression level which may not be evident at gene level. In this direction, we utilized our prior knowledge about significant alternatively spliced genes and chose ADAM12 and MUC4 for further characterization in a metastatic cell line model. These genes were found to be good prognostic indicators in The Cancer Genome Atlas database. We studied the gene organization and designed primers to specifically amplify a group of isoforms. Differential expression of these group of isoforms was observed in normal, primary and metastatic colorectal cancer cell lines. We further validated the results using sanger sequencing. Isoform expression was found to respond to the 5-fluorouracil treatment. RNAseq analysis of the cell lines further validated the differential expression of gene isoforms. Successful detection of ADAM12 and MUC4 in cell lysates varied according to the antibody used which may reflect differential expression of isoforms. This comprehensive study underscores the importance of studying alternatively spliced isoforms and their probable used as prognostic or predictive biomarkers.

CDC42 (cell division cycle protein 42) belongs to the Rho GTPase family that is known to control the signaling axis that regulates several cellular functions, including cell cycle progression, migration, and proliferation. However, the functional characterization of the CDC42 gene in mammalian physiology remains largely unclear. Here, we report the genetic and functional characterization of a non-consanguineous Saudi family with a single affected individual. Clinical examinations revealed poor wound healing, heterotopia of the brain, pancytopenia, and recurrent infections. Whole exome sequencing revealed a de novo missense variant (c.101C > A, p.Pro34Gln) in the CDC42 gene. The functional assays revealed a substantial reduction in the growth and motility of the patient cells as compared to the normal cells control. Homology three-dimensional (3-D) modeling of CDC42 revealed that the Pro34 is important for the proper protein secondary structure. In conclusion, we report a candidate disease-causing variant, which requires further confirmation for the etiology of CDC42 pathogenesis. This represents the first case from the Saudi population. The current study adds to the spectrum of mutations in the CDC42 gene that might help in genetic counseling and contributes to the CDC42-related genetic and functional characterization. However, further studies into the molecular mechanisms that are involved are needed in order to determine the role of the CDC42 gene associated with aberrant cell migration and immune response.