Molecular determinants of response to 5-fluorouracil-based chemotherapy in colorectal cancer: The undisputable role of microribonucleic acids

5-flurouracil(5-FU)-based chemotherapy is the main pharmacological therapy for advanced colorectal cancer(CRC).Despite significant progress in the treatment of CRC during the last decades,5-FU drug resistance remains the most important cause of failure in CRC therapy.Resistance to 5-FU is a complex and multistep process.Different mechanisms including microsatellite instability,increased expression level of key enzyme thymidylate synthase and its polymorphism,increased level of 5-FU-activating enzymes and mutation of TP53 are proposed as the main determinants of resistance to 5-FU in CRC cells.Recently,microribonucleic acids(miRNA)and their alterations were found to have a crucial role in 5-FU resistance.In this regard,the miRNA-mediated mechanisms of 5-FU drug resistance reside among the new fields of pharmacogenetics of CRC drug response that has not been completely discovered.Identification of the biological markers that are related to response to 5-FU-based chemotherapy is an emerging field of precision medicine.This approach will have an important role in defining those patients who are most likely to benefit from 5-FU-based chemotherapy in the future.Thereby,the identification of 5-FU drug resistance mechanisms is an essential step to predict and eventually overcome resistance.In the present comprehensive review,we will summarize the latest knowledge regarding the molecular determinants of response to 5-FU-based chemotherapy in CRC by emphasizing the role of miRNAs.

PI3K/AKT signaling pathway as a critical regulator of Cisplatin response in tumor cells

Chemotherapy is one of the main therapeutic modalities for cancer patients.Cisplatin(CDDP),as one of thefirst-line drugs,is of great importance in the chemotherapy of various tumors.However,a significant percentage of cancer patients are resistant to CDDP treatment.Due to the CDDP side effects on normal tissues,the diagnosis of CDDP resistance is required to suggest the most efficient therapeutic strategies for cancer patients.Several molecular mechanisms and signaling pathways are associated with CDDP response.The PI3K/AKT signaling pathway has a pivotal role in the transmission of extracellular signals into the cells to regulate various pathophysiological processes such as cell proliferation,migration,and drug resistance.In the present review,we summarized all of the studies which have been reported on the role of PI3K/AKT pathway in regulation of CDDP response.It was shown that the PI3K/AKT pathway is mainly involved in CDDP response in lung,ovarian,and gastrointestinal cancers.It was also observed that the non-coding RNAs have a key role in CDDP response by regulation of PI3K/AKT pathway.This review paves the way for suggesting a PI3K/AKT-related panel marker for the prediction of CDDP response in different cancer patients.

Some of the experimental and clinical aspects of the effects of the maternal diabetes on developing hippocampus

Diabetes mellitus during pregnancy is associated with an increased risk of multiple congenital anomalies in progeny.There are sufficient evidence suggesting that the children of diabetic women exhibit intellectual and behavioral abnormalities accompanied by modification of hippocampus structure and function.Although,the exact mechanism by which maternal diabetes affects the developing hippocampus remains to be defined.Multiple biological alterations,including hyperglycemia,hyperinsulinemia,oxidative stress,hypoxia,and iron deficiency occur in pregnancies with diabetes and affect the development of central nervous system(CNS) of the fetus.The conclusion from several studies is that disturbance in glucose and insulin homeostasis in mothers and infants are major teratogenic factor in the development of CNS.Insulin and Insulin-like growth factor-1(IGF-1) are two key regulators of CNS function and development.Insulin and IGF-1 receptors(IR and IGF1 R,respectively) are distributed in a highly specific pattern with the high density in some brain regions such as hippocampus.Recent researches have clearly established that maternal diabetes disrupts the regulation of both IR and IGF1 R in the hippocampus of rat newborn.Dissecting out the mechanisms responsible for maternal diabetes-related changes in the development of hippocampus is helping to prevent from impaired cognitive and memory functions in offspring.

A novel CRX mutation by whole-exome sequencing in an autosomal dominant cone-rod dystrophy pedigree

AIMTo identify the disease-causing gene mutation in a Chinese pedigree with autosomal dominant cone-rod dystrophy (adCORD).METHODSA southern Chinese adCORD pedigree including 9 affected individuals was studied. Whole-exome sequencing (WES), coupling the Agilent whole-exome capture system to the Illumina HiSeq 2000 DNA sequencing platform was used to search the specific gene mutation in 3 affected family members and 1 unaffected member. After a suggested variant was found through the data analysis, the putative mutation was validated by Sanger DNA sequencing of samples from all available family members.RESULTSThe results of both WES and Sanger sequencing revealed a novel nonsense mutation c.C766T (p.Q256X) within exon 5 of CRX gene which was pathogenic for adCORD in this family. The mutation could affect photoreceptor-specific gene expression with a dominant-negative effect and resulted in loss of the OTX tail, thus the mutant protein occupies the CRX-binding site in target promoters without establishing an interaction and, consequently, may block transactivation.CONCLUSIONAll modes of Mendelian inheritance in CORD have been observed, and genetic heterogeneity is a hallmark of CORD. Therefore, conventional genetic diagnosis of CORD would be time-consuming and labor-intensive. Our study indicated the robustness and cost-effectiveness of WES in the genetic diagnosis of CORD.