A therapeutic keypad lock decoded in drug resistant cancer cells.

A molecular keypad lock that displays photodynamic activity when exposed to glutathione (GSH), esterase and light in the given order, is fabricated and its efficacy in drug resistant MCF7 cancer cells is investigated. The first two inputs are common drug resistant tumor markers. GSH reacts with the agent and shifts the absorption wavelength. Esterase separates the quencher from the structure, further activating the agent. After these sequential exposures, the molecular keypad lock is exposed to light and produces cytotoxic singlet oxygen. Among many possible combinations, only one 'key' can activate the agent, and initiate a photodynamic response. Paclitaxel resistant MCF7 cells are selectively killed. This work presents the first ever biological application of small molecular keypad locks.

Response to trastuzumab and investigation of expression profiles of matrix metalloproteinase-related proteins in primary breast cancer stem cells.

Breast cancer (BC) is the leading cause of cancer deaths in women. One of the reasons for the failure of BC treatment is reportedly the ineffectiveness of chemotherapeutic drugs against breast cancer stem-like cells (BCSCs). HER2 receptors have an important role in the self-renewal of BCSCs. Matrix metalloproteinase (MMP) and cytokine levels were found to be higher in BCSCs, which demonstrates their potential metastatic capacity. Therefore, the aim of this study was to evaluate the response of BCSCs to trastuzumab and to investigate the MMP levels in primary breast cancer cells and HER2+ BCSCs. Tumour tissue samples were obtained during surgical intervention from ten breast cancer patients, and primary culture cells were established from these tissues. Four major molecular subgroups were sorted from the primary culture: HER2+ BCSCs (CD44+CD24-HER2+), HER2- BCSCs (CD44+CD24-HER2-), HER2- primary culture cells (CD44+CD24+HER2-) and triple positive primary culture cells (CD44+CD24+HER2+). These cells were cultured and treated with trastuzumab, paclitaxel, carboplatin, and the combination of those three drugs for 96 h. Cellular responses to these drugs were determined by XTT cytotoxicity test. MMPs and cytokine array analysis showed that MMPs and TIMP-1, TIMP-2 proteins were expressed more in HER2+ BCSCs than in primary culture. HER2- BCSCs were more resistant to drugs than HER2+ BCSCs. Our findings suggest that the presence of HER2- BCSCs may be responsible for primary trastuzumab resistance in HER2+ BC cell population. Further studies investigating the function of MMPs are needed for drug targeting of BCSCs.