Modulation of photodynamic therapy effect by stromal HIF-1

FERRARA MG; RUMIE VITTAR NB; IBARRA LE; LAMBERTI MJ

Mar del Plata

Congreso; REUNIÓN DE SOCIEDADES DE BIOCIENCIAS 2020; 2020

SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA (SAIC)

Tumor microenvironment (TME) is a unique interactive ecosystem, where fibroblasts represent the most abundant stromal population that supports tumor growth. Due to aberrant and disorganized tumor proliferation, another common feature of TME is hypoxic regions development, in which HIF-1 acts as the main molecular mediator of adaptability. We have previously shown that photodynamic therapy (PDT), an antitumor therapy based on the combination of light, oxygen, and a photosensitizer (PS), promoted HIF-1 activation on tumor cells. Concomitantly, we also demonstrated a direct association of tumoral HIF-1 and therapeutic resistance to PDT. However, it is unknown whether this transcription factor modulates surrounding stroma response to photo-intervention. In this study, we investigated the contribution of stromal in PS generation and its involvement in photo-cytotoxicity. TME was mimicked using homotypic spheroids of fibroblast (MRC-5 wild type or shHIF-1) or colorectal cancer cells (SW480 shHIF-1), and heterotypic spheroids composed of 1:1 mixed fibroblast/tumor cells. Stromal HIF-1 status was sensed through a reporter gene construct. The production of PS: Protoporphyrin IX (PpIX) was quantified by fluorescence microscopy. Cell viability was analyzed through MTT assay. Our findings determined that HIF-1 silencing conferred resistance to PDT in stroma 3D monoculture, without modifying the generation of PpIX. On the other hand, in heterotypic spheroids, the profile of PpIX production was associated with the hypoxic-preferential distribution of the stroma. Surprisingly, whereas stromal HIF-1 status did not impact on therapeutic resistance, the cross-talk between fibroblasts and cancer cells improved the effect of PDT. Overall, these results suggest that response to PDT differs across hypoxic populations within TME. As a consequence, the overall effectiveness of PDT is not defined only by tumor sensitivity, thereby stroma behavior should also be considered to certainly predict therapeutic outcome