The Role of miRNAs in Childhood Acute Lymphoblastic Leukemia Relapse and the Associated Molecular Mechanisms.

Acute lymphoblastic leukemia (ALL) is the most common cancer in children worldwide. Although ALL patients' overall survival rates in wealthy countries currently surpass 80%, 15-20% of patients still experience relapse. The underlying mechanisms of relapse are still not fully understood, and little progress has been made in treating refractory or relapsed disease. Disease relapse and treatment failure are common causes of leukemia-related death. In ALL relapse, several gene signatures have been identified, but it is also important to study miRNAs involved in ALL relapse in an effort to avoid relapse and to achieve better survival rates since miRNAs regulate target genes that participate in signaling pathways involved in relapse, such as those related to drug resistance, survival signals, and antiapoptotic mechanisms. Several miRNAs, such as miR-24, miR-27a, miR-99/100, miR-124, miR-1225b, miR-128b, miR-142-3p, miR-155 and miR-335-3p, are valuable biomarkers for prognosis and treatment response in ALL patients. Thus, this review aimed to analyze the primary miRNAs involved in pediatric ALL relapse and explore the underlying molecular mechanisms in an effort to identify miRNAs that may be potential candidates for anti-ALL therapy soon.

Plasma levels of YKL-40 as a prognostic factor in childhood acute lymphoblastic leukemia.

YKL-40, also known as chitinase-3-like protein 1 (CHI3L1), is an inflammatory glycoprotein secreted by different types of cells, such as inflammatory cells. The levels of this protein are elevated in the serum or plasma of patients with different types of cancer, and high concentrations are associated with poor prognosis and short survival in patients with liver, breast, lung, bladder and endometrial cancers. In Mexico, acute lymphoblastic leukemia (ALL) is the most common type of cancer affecting the pediatric population. The prognosis of patients with ALL is difficult to establish. Hence, the objective of the present study was to analyze the plasma levels of YKL-40 in Mexican children with ALL and investigate its role as a prognostic factor. A case-control study was performed in a population of 90 children aged 1-18 years, among whom 45 had ALL and 45 were hematologically healthy. The levels of YKL-40 in plasma samples were measured using ELISA and were found to be significantly higher in children with ALL compared with those in controls (P<0.0001). Children with ALL who had high plasma levels of YKL-40 (≥36.34 ng/ml) had shorter survival compared with those with low levels (<36.34 ng/ml; P<0.05). The findings of the present study revealed that the YKL-40 plasma level, age/initial leukocyte count and central nervous system invasion were associated with the prognosis of children with ALL [odds ratio (OR)=6.06, 95% confidence interval (CI): 1.1-31.6, P=0.03; OR=8.53, 95% CI: 1.2-58.2, P=0.03; and OR=6.45, 95% CI: 1.01-41.2, P=0.04, respectively]. Therefore, YKL-40 plasma levels may serve as a prognostic biomarker in pediatric patients with ALL.