Inducible 70kDa Heat Shock Protein and Autophagy-related Protein P62 Levels in Women With Breast Cancer: an Exploratory Investigation

Abstract Background: Peripheral blood mononuclear cells (PBMCs) respond to altered physiological conditions to alleviate the threat. The inducible 70kDa heat shock protein (HSPA1A) protects proteins from degradation. Autophagy is an intracellular process that removes damaged proteins and recycles their components to the cytoplasm. Sequestosome-1 (p62) is a protein consumed during autophagy. We hypothesized that the PBMC response to a malignant breast mass involves elevated production of HSPA1A and a decrease in intracellular p62.Methods: In this study 46 women had their breast mass excised. PBMCs were isolated and intracellular levels of HSPA1A and p62 were quantitated by ELISA. Differences between women with a benign or malignant breast mass were determined. Results: A breast malignancy was diagnosed in 38 women (82.6%) while 8 had a benign lesion. Mean intracellular HSPA1A levels were 79.3 ng/ml in PBMCs from women with a malignant lesion and 44.2 ng/ml in controls (p=0.04). The mean PBMC p62 level was 2.3 ng/ml in women with a benign breast lesion as opposed to 0.6 ng/ml in those with breast cancer (p<0.001). Mean p62 levels were also lower in women with invasive carcinoma and a positive lymph node biopsy when compared to those with in-situ carcinoma or absence of lymphadenopathy, respectively. Conclusion: Intracellular HSPA1A and p62 levels in PBMCs differ between women with a malignant or benign breast lesion. These measurements may be of value in the preoperative triage of women with a breast mass.