A reverse-transcriptase-subunit of telomerase (hTERT) derived peptide, GV1001, 
has been developed as a vaccine against various cancers. Previously, we have 
shown that GV1001 interacts with heat shock proteins (HSPs) and penetrates cell 
membranes to be localized in the cytoplasm. In this study, we have found that 
GV1001 lowered the level of intracellular and surface HSPs of various cancer 
cells. In hypoxic conditions, GV1001 treatment of cancer cells resulted in 
decreases of HSP90, HSP70, and HIF-1α. Subsequently, proliferation of cancer 
cells and synthesis of VEGF were significantly reduced by treatment using GV1001 
in hypoxic conditions. In an experiment using a nude mouse xenograft model, 
GV1001 exerted a similar tumor suppressive effect, further confirming its 
anti-tumor efficacy. Higher apoptotic cell death, reduced proliferation of 
cells, and fewer blood vessels were observed in GV1001-treated tumors compared 
to control. In addition, significant reduction of Tie2+ CD11b+ monocytes, which 
were recruited by VEGF from tumor cells and play a critical role in 
angiogenesis, was observed in GV1001-treated tumors. Collectively, the results 
suggest that GV1001 possesses potential therapeutic efficacy in addition to its 
ability to induce anti-cancer immune responses by suppressing both HSP70 and 
HSP90.