In-person Flash Talk & E-Poster Presentation 34th Lorne Cancer Conference 2022

Combined targeting strategy of gp130/STAT3 inhibitors with chemotherapy and SMAC mimetics potently enhances pro-apoptotic responses in colorectal cancer (#12)

Rhynelle Dmello 1 , Michelle Palmieri 2 , Pathum Thilakasiri 1 , Sarah Bennett 1 , Ivan Poon 3 , Eduard Batlle 4 , Matthias Ernst 1 , Ashwini Chand 1
  1. Olivia Newton John Cancer Research Institute and School of Cancer Medicine, La Trobe Univeristy, Melbourne, VIC, Australia
  2. Walter and Eliza Hall Intitute of Medical Research (WEHI), Melbourne, VIC, Australia
  3. Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
  4. Institute for Research in Biomedicine, Barcelona, Spain

Inflammatory cytokines, such as interleukin-6 (IL-6) and IL-11, activate the signal transducer and activator of transcription 3 (STAT3), which drives the gene transcription of cellular processes attributed as hallmarks of cancer. High levels of these cytokines in combination with driver mutations, facilitate tumour progression in pre-clinical models of colon cancer. Previous studies in our laboratory identified bazedoxifene (BZA) as a small molecule inhibitor of gp130 (the receptor common to the IL-6 family of cytokines), selectively suppressing IL-6 and IL-11 signalling to reduce colon and gastric tumour growth in vivo (Thilakasiri et al, EMBO Mol Med 2019). 

The aim of this study is to determine the combined effects of BZA in combination with standard of care chemotherapy and SMAC mimetics to mediate anti-tumour effects via pro-apoptotic signalling pathways in colon cancer. Additionally, we also assessed the combined effects of these combinations on other cell signalling pathways in colon cancer. 

Using organoids derived from the sigmoid and ascending colon of stage II and stage III patients, the combined efficacy of BZA and chemotherapy (5-fluorouracil, oxaliplatin and the active metabolite of irrinotecan-SN38) as well as BZA and SMAC mimetics (LCL-161 and Birinipant) were assessed using drug synergy assays. The effects of these drug combinations on pro-apoptotic pathways were analysed using flow cytometry and dot protein arrays. Further, the effects of the combinations on cell signalling pathways were assessed using reverse phase protein arrays and the levels of STAT3 activation in response to gp130/STAT3 signalling were characterised by Western blotting.

Our results demonstrated that treatment with BZA combined with standard of care chemotherapy and SMAC mimetics increased apoptotic cell signalling in colon cancer cells and patient derived organoids. BZA treatment sensitised cells to chemotherapy treatment and SMAC mimetics via the activation of NF-kβ signalling leading to a potent increase in apoptosis demonstrating that co-targeting of gp130/STAT3 signalling inhibition with chemotherapy and SMAC mimetics could be a novel therapeutic angle for patients with early and advanced stage colon cancer.

 

  1. Thilakasiri, P., Huynh, J., Poh, A.R., Tan, C.W., Nero, T.L., Tran, K., Parslow, A.C., Afshar‐Sterle, S., Baloyan, D., Hannan, N.J. and Buchert, M., 2019. Repurposing the selective estrogen receptor modulator bazedoxifene to suppress gastrointestinal cancer growth. EMBO molecular medicine, 11(4), p.e9539. Vancouver