Explore the role of oral bacteria in the chemoresistance of pancreatic cancer

Pancreatic cancer is a highly lethal disease with a 5-year survival rate below 8% and is projected to become the second leading cause of cancer-related deaths in 2020. The reasons for this poor prognosis include the detection of the tumor in the late disease stage and the poor response to chemotherapy. So far the most common chemotherapeutic protocols are i.e. FOLFIRINOX (a combination of 5-fluorouracil (5-FU), leucovorin, irinotecan and oxaliplatin) and gemcitabine/nab-paclitaxel. These protocols only resulted in modest survival benefits (< 1 year). Growing evidence suggests that microbes can influence the efficacy of anticancer treatments. Recent studies, including ours, demonstrate that bacteria are a component of pancreatic tumor microenvironment, and they may also play a critical role in mediating resistance to chemotheraphy. (REF1)

The microbiota isolated from the pancreas tissue indicated that these microbes might come from oral cavity.  Remarkably, a most recent prospective study showed that the presence of two oral pathogens, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, was associated with an elevated risk of developing pancreatic cancer.(REF2) In addition, high levels of antibodies against Porphyromonas gingivalis were shown to double the risk of pancreatic cancer.(REF3) However, the definitive role for microbiota as either cause or reaction after tissue inflammation which is commonly associated to pancreatic cancer remains unclear. All these data support further studies aimed at unraveling the complex interaction between oral bacteria and pancreatic cancer.

Since a recent study showed the role of bacteria in resistance to gemcitabine, the present project will focus on the potential effects of oral bacteria on the chemoresistance of pancreatic cells to the different chemotherapeutic drugs which are used in the standard treatment of pancreatic cancer patients.

To this end, the specific goals of the project include 1) to understand the involvement of oral bacteria in the resistance of pancreatic cells to chemotherapies and 2) to explore the molecular mechanisms of this involvement. To achieve these goals, several oral bacterial species, including the two oral pathogen mentioned above will be coincubated with pancreatic cancer cells. The resistance of the cells to selected chemotherapy (eg, gemcitabine, nab-paclitaxel, oxaliplatin, irinotecan and 5-fluorouracil) will be evaluated with the Sulforhodamine-B (SRB) colorimetric assay. Various isogenic knockout mutants of oral bacteria and genetically modified pancreatic cells will be included in the assay to investigate the underlying mechanism.

Techniques to be used in this project include:

Aerobic and anaerobic culturing of bacteria
Culturing of human cancer cell

- SRB colorimetric assay for the evaluation of drug sensitivity/resistance, through the determination of the IC50 (eg, the drug concentration causing 50% inhibition of the cancer cell growth)
- Microscopic examination of cellular features
- Flow cytometry (for the analysis of celle cycle and apoptosis induction)

Dr. Ilaria Carnevale, i.carnevale@vumc.nl; Dr. Dongmei Deng, d.deng@acta.nl

1. Geller et al., Science 357, 1156-1160 (2017)
2. Farrell JJ et al., Gut 61, 582-588 (2012)
3. Michaud DS, Izard J. Cancer J 20, 203-206 (2014)