Lightning talk + Poster Australasian Extracellular Vesicles Conference 2020

The potential of calcium loaded pH-sensitive liposomes to suppress small extracellular vesicles mediated chemo-resistance in pancreatic cancer (#40)

Mingtan Tang 1 , Sasi Bhushan Yarragudi 1 , Tianjiao Geng 1 , Euphemia Leung 2 , Larry Chamley 3 , Zimei Wu 1
  1. School of Pharmacy, University of Auckland, Auckland, New Zealand
  2. Auckland Cancer Society Research Centre, University of Auckland, Auckland, New Zealand
  3. Department of Obstetrics and Gynaecology, University of Auckland, Auckland, New Zealand


Small Extracellular Vesicles (SEVs) play a role in chemo-resistance in cancer treatment via exocytosis of chemotherapeutics. Ca2+ released from calcium loaded pH-sensitive liposomes (Ca-pSLs) in the endosomes can induce osmotic pressure and might cause endosomal rupture. Previously we have developed a gemcitabine resistant cell line Gr2000 from MIA PaCa-2 pancreatic cancer cell line.


To investigate the potential of Ca-pSLs to suppress SEVs mediated chemo-resistance


MIA PaCa-2 and Gr2000 cells were treated with free gemcitabine for 3 h and then SEVs were isolated by gradient ultracentrifugation of culture medium. The concentration of SEVs were analysed using Nanosight NS300®. After cells were stained with Lysotracker for late endosome and treated with Rh-PE labelled Ca-pSLs or Ca-free-pSLs, the fluorescence was monitored with live cell imaging Olympus FV1000 confocal microscope. Cells were treated with Ca-pSLs or Ca-free-pSLs prepared with thin film hydration method for 2 h, then SEVs were isolated as mentioned above.


MIA PaCa-2 and Gr2000 cells showed a similar production rate of SEVs. Gemcitabine treatment induced significant increase in SEVs production (per 106 cells · day) of Gr2000 (556 ± 19 vs 385 ± 37).  In contrast non-resistant cells MIA PaCa-2 showed minor change (368 ± 14 vs 324 ± 24). Ca‑pSLs (drug free)  reduced SEVs secretion from both MIA PaCa-2 and Gr2000 cells by 2 and 3 times, respectively. Interestingly, Ca-free-pSLs showed similar inhibition effect. In the Ca-pSLs treated cells, late endosomes fluorescence decreased from 1 to 2h, indicating endosome rupture. In contrast, Ca-free-pSLs did not affect the signal over 2 h.


Ca-pSLs have the potential to overcome gemcitabine resistance by reducing SEVs secretion. Further study is ongoing with gemcitabine loaded Ca-free-pSLs using non pH-sensitive liposomes as references.