Hsp70 in Cancer: Partner or Traitor to Immune System

Heat shock protein 70.1 (Hsp70.1), also known as Hsp70, is a highly conserved member of the heat shock protein family that exists in all living organisms and determines the protein fate as molecular chaperones. Hsp70 basal expression is undetectable or low in most unstressed normal cells, however, its abundant presence in several types of human cancer cells is reported. Several studies support upregulated Hsp70 involved in tumor progression and drug resistance through modulation of cell death pathways and suppresses anticancer immune responses. However, numerous studies have confirmed that Hsp70 can also induce anticancer immune responses through the activation of immune cells in particular antigen-presenting cells (APCs). Regarding the significant and the promising role of vaccines in cancer immunotherapy, identification and characterization of the overexpressed Hsp70 as a potential immune stimulatory factor can pave the path for development of highly effective anticancer vaccines. In this review, we will discuss the interactions of Hsp70 with components of the immune system in cancers as well as possible strategies to harness Hsp70 for eliciting anticancer immune responses.