The potential of using blood circular RNA as liquid biopsy biomarker for human diseases

Circular RNA (circRNA) is a novel class of single-stranded RNAs with a closed loop structure. The majority of circRNAs are formed by a back-splicing process in pre-mRNA splicing. Their expression is dynamically regulated and shows spatiotemporal patterns among cell types, tissues and developmental stages. CircRNAs have important biological functions in many physiological processes, and their aberrant expression is implicated in many human diseases. Due to their high stability, circRNAs are becoming promising biomarkers in many human diseases, such as cardiovascular diseases, autoimmune diseases and human cancers. In this review, we focus on the translational potential of using human blood circRNAs as liquid biopsy biomarkers for human diseases. We highlight their abundant expression, essential biological functions and significant correlations to human diseases in various components of peripheral blood, including whole blood, blood cells and extracellular vesicles. In addition, we summarize the current knowledge of blood circRNA biomarkers for disease diagnosis or prognosis.

Detección molecular de enfermedad mínima residual en melanoma y otros tumores sólidos / Molecular detection of minimal residual disease in melanoma and solid tumors

La disponibilidad de métodos altamente sensibles y específicos para la detección de enfermedad mínima residual en pacientes con tumores sólidos podría tener importantes consecuencias pronósticas y terapéuticas. Uno de los métodos más usados para la detección molecular de células cancerosas es la técnica de RT-PCR, que permite la amplificación de secuencias de ARNm específicas de distintos tejidos. La misma fue aplicada por primera vez en la detección de células tumorales circulantes en sangre periférica de pacientes con melanoma avanzado, poco tiempo después fue adaptada para la búsqueda de enfermedad mínima residual en otros tumores sólidos. El objetivo de la presente revisión es evaluar la información publicada desde el primer estudio sobre este tema en 1991 y analizar el valor clínico de los hallazgos obtenidos. Se discute también la importancia del manejo de la muestra y de la estandarización de los procedimientos de RT-PCR.

The availability of highly sensitive and specific methods for the detection of minimal residual disease in patients with solid tumors may have important prognostic and therapeutic implications. One of the most widely used methods for the molecular detection of cancer cells is the RT-PCR technique, which leads to the amplification of tissue-specific mRNA. It was firstly applied in the detection of circulating tumor cells in peripheral blood of patients with advanced melanoma; and soon it was adapted for the detection of minimal residual disease in other solid tumors. The aim of the present review is to evaluate the published data since the first study in 1991 and to analyze the clinical value of the findings obtained. The importance of sample handling and standardization of RT-PCR procedures is also discussed.

Construction of a human Fab phage display library from antibody repertoires of osteosarcoma patients

Osteosarcoma is the commonest type of primary malignant bone tumor, frequently found in adolescents at sites of rapid bone growth. Despite current management protocols, up to half of the patients succumb to this disease. Moreover, there is no well-characterized molecular marker for diagnosis and prognosis. Since phage display methodology allows the selection of human antibody fragments with potential use in clinical applications, we applied this procedure to construct a recombinant Fab (antigen binding fragment) library from patients with osteosarcoma. We used peripheral blood lymphocyte total RNA from 11 osteosarcoma patients and cloned recombinant Fab representing the micro, gamma and kappa chain antibody repertoires of these individuals. The resulting library was cloned in the pComb3X vector and attained 1.45 x 10(8) different functional forms. BstO I fingerprinting and DNA sequencing analysis of randomly selected clones revealed the diversity of the library, demonstrating that Fab harbors Vkappa chains from subgroups I to V, biased towards the A27 fragment, as normally reported for the human repertoire. Analysis of the VH repertoire revealed that our library has a slight bias towards the VH4 family, instead of the usually reported VH3. This is the first description of a phage display library from osteosarcoma patients. We believe these human Fab fragments will provide a valuable tool for the study of this neoplasia and could also contribute to improvements in the diagnosis of this disease.