9th Drug Chemistry Conference, Antalya, Türkiye, 8 - 11 Nisan 2021, ss.77
Trastuzumab is a recombinant DNA-derived humanized monoclonal antibody that selectively inhibits
HER2-positive breast cancer tumor formation as a single agent and in combination with other
chemotherapeutics and natural products. Binding with high affinity to the extracellular domain of HER2
receptor, trastuzumab inhibits the proliferation of tumor cells that overexpress HER2 [1]. In order to
increase therapeutic efficiency, administration of trastuzumab in combination with FDA approved
drugs and natural products have been investigated in pre-clinical and clinical studies in cancer [1,2].
Venoms have been used in traditional medicine to treat various diseases for many years. Spider venom
contains peptides and proteins which target a different receptor, ion channels, and enzymes. And
these bioactive compounds exhibit cytotoxic properties to several cancer cells through apoptosis
modulation, anti-proliferation, inhibition of enzymatic activities, and cell cycle alterations [3].
Tarantula cubensis alcoholic extract is prepared from the venom of spider T. cubensis. It is used as
homeopathic agent which has shown anti-tumor, anti-inflammatory and antiphlogistic effects in
veterinary medicine. It was also reported that T. cubensis alcoholic extract has high cytotoxic effects
on various cancer types including breast cancer [4].
In this research, we investigated the synergistic anticancer effect of trastuzumab and T. cubensis
alcoholic extract on HER2-positive human breast cancer cell (MDA-MB-453). The values of CI
(Combination Index) were calculated using CompuSyn free software to identify synergistic effect of
trastuzumab and T. cubensis alcoholic extract. Cell cycle, various stages of apoptosis and the presence
of multiple caspases were detected with the Muse® Cell Cycle Kit, Muse® Annexin V & Dead Cell Kit
and Muse®, MultiCaspase Kit, respectively. In addition, the expression of Bax, Bcl-2, Caspase-3,
Caspase-9, Apaf-1 and β-catenin genes was determined by RT-qPCR, β-actin was used as a reference
gene. Protein levels of Bax, Bcl-2, Caspase-3 were determined by ELISA. Additionally, Apaf-1, β-catenin,
Caspase-9 expressions were detected by Western Blotting.