Detecting cancer metastasis and accompanying protein biomarkers at single cell levels using a 3D-printed microfluidic immunoarray

A low-cost microfluidic microarray capable of lysing cells and quantifying proteins released after lysis was designed and 3D-printed. The array lyses cells on-chip in lysis buffer augmented with a 2s pulse of a sonic cell disruptor. Detection of desmoglein 3 (DSG3), a metastatic biomarker for head and neck squamous cell carcinoma (HNSCC), along with two accompanying HNSCC biomarkers from a single cell lysate of oral cancer cell cultures was demonstrated. A lysis chamber and reagent compartments deliver sample and reagents into detection chambers decorated with capture antibodies immobilized onto inner walls coated with a highly swollen 3D chitosan hydrogel film. Sandwich immunoassays are achieved when captured analytes labeled with biotinylated secondary antibodies, which then capture streptavidin-poly [horse radish peroxidase] (Poly-HRP). Subsequent delivery of super-bright femto-luminol with H2O2 generates chemiluminescence captured with a CCD camera. DSG3 is membrane-bound protein in HNSCC cells of invaded lymph nodes, vascular endothelial growth factor-A (VEGF-A), vascular endothelial growth factor-C (VEGF-C) were positive controls overexpressed into the HNSCC culture medium. Beta-tubulin (β-Tub) was used as a loading control to estimate the number of cells in analyzed samples. Limits of detection (LOD) were 0.10 fg/mL for DSG3, and 0.20 fg/mL for VEGF-A, VEGF-C and β-Tub. Three orders of magnitude semilogarithmic dynamic ranges were achieved. VEGF-A showed high in-cell expression, but VEGF-C had low levels inside cells. The very low LODs enabled quantifying these proteins released from single cells. Strong correlation between results from on-chip cell lysis, conventional off-line lysis and ELISA confirmed accuracy.

Heregulin and HER3 are prognostic biomarkers in oropharyngeal squamous cell carcinoma

BACKGROUND

Although heregulin and human epidermal growth factor receptor 3 (HER3) are frequently expressed at high levels in patients with head and neck cancer, their prognostic value remains unclear. The authors explored the prognostic significance of heregulin/HER3 expression in patients with oropharyngeal squamous cell carcinoma (OPSCC), taking into account other HER family members as well as p16 status.

METHODS

Ninety-six primary tumor specimens from patients with OPSCC were retrospectively collected and analyzed for heregulin messenger RNA (mRNA) using in situ hybridization and for HER3, epidermal growth factor receptor, and human epidermal growth factor receptor 2 (HER2) using quantitative immunohistochemistry. Heregulin and HER3 mRNA levels were also examined among different tumor types using The Cancer Genome Atlas database.

RESULTS

High heregulin mRNA (> the median) correlated significantly with poor overall survival (OS) (hazard ratio [HR], 8.48; 95% confidence interval [95% CI], 2.17-33.17 [P =.002]) but not disease-free survival (HR, 1.52; 95% CI, 0.64-3.65 [P =.341]) in patients with OPSCC. Heregulin mRNA correlated negatively with OS in both patients with p16-positive (P =.049) and p16-negative (P =.091) OPSCC on univariate analysis. High HER3 (> the median) also correlated with poor OS (HR, 4.68; 95% CI, 1.47-14.90 [P =.009]) on multivariate analysis. Epidermal growth factor receptor levels independently correlated with disease-free survival (P =.025) and inversely correlated with p16 status (P =.012). In addition, The Cancer Genome Atlas data demonstrated that head and neck squamous cell carcinoma exhibits higher heregulin expression compared with other solid tumor types examined.

CONCLUSIONS

High heregulin mRNA and high HER3 protein levels were found to independently correlate with poor OS in patients with OPSCC. These data support targeting HER3 in patients with heregulin-high OPSCC and warrant further clinical investigation.