PROFILING CIRCULATING MIRNA WITHOUT PCR FOR EARLY DETECTION OF PANCREATIC CANCER


Year of Award:
2015
Award Type:
R43
Project Number:
CA199058
RFA Number:
PAR-13-327
Technology Track:
Molecular & Cellular Analysis Technologies
PI/Project Leader:
SARAF, RAVI
Other PI or Project Leader:
ROY, SANTANU
Institution:
VAJRA INSTRUMENTS, INC.
Pancreatic cancer (PaC) has a poor prognosis in most cases due to the lack of early detection owing to its nonspecific, asymptomatic nature. An effective, inexpensive screening tool is needed for early diagnosis (within 15 years of tumor initiation). It is well accepted that genomic instability is a hallmark of cancer. Recent research indicates that less than hundred microRNA (miRNA) sequences specifically generated by tumors are sufficient for early detection of PaC and other cancers for effective intervention with excellent prognosis. MiRNA can be extracted from urine and blood using standard kits. The key challenge is to detect specific biomarkers in the thousand-fold large background of miRNA sequences that body normally produces. While quantitative reverse transcribe-polymerase chain reaction (qRT-PCR) is an effective tool for miRNA profiling, it is prohibitively expensive fo screening. A microarray is an inexpensive alternative. However, due to the small size of miRNA, a conventional microarray is not reliable due to large background from nonspecific binding. A disruptive technology is needed to read microarrays of miRNA at high specificity with minimal background from the normal miRNA sequences and high sensitivity to avoid PCR amplification. Owing to the small size of miRNA, PCR is an added expensive complexity. It is well known that electrochemical detection has excellent specificity with virtually no background from nonspecific binding of targets to microarray of probes. The key limitations of this active detection method are: (a) only one target sequence per electrode can be detected, and (b) the redox current decreases as the sensor electrode size diminishes , making multiplexing difficult. A method developed in Saraf's lab, at the University of Nebraska-Lincoln, can electrochemically 'read' microarray spots on a monolith electrode by simply scanning a laser with a beam size of ~10 æm to quantitatively measure the local redox current. Published studies indicate that Scanning Electrometer for Electrical Double-layer (SEED) has (conservative) responsivity of