Overall, the aim of this review is to provide an informative resource for those in the MSI community who are interested in improving MSI data quality and analysis or using MSI for novel applications. Particularly, we discuss advances for the last 2 years in sample preparation, instrumentation, quantitation, statistics, and multi-modal imaging that have allowed MSI to emerge as a powerful technique in the clinic. Also, several, novel biological applications are highlighted that demonstrate the potential for the future of the field.
There is a lack of understanding of how stromal cells and increased extracellular matrix deposition influences chemotherapeutic response in pancreatic ductal adenocarcinoma (PDAC). The lack of unbiased, quantitative characterization of preclinical cell culture models including tumor stroma is a main factor preventing translation of new therapies for PDAC. We hypothesize that proteins and their expression levels will change when cancer cells are cultured with pancreatic stellate cells (PSCs) and that culturing cells in a 3D stromal microenvironment will provide more in vivo like proteomes. Here, we use mass spectrometry (MS) as a tool for protein characterization and as a label-free method for analyzing spatial location of therapeutics in 3D cell culture. While animal models are typically used to study drug distribution and efficacy, animal models of PDAC are unable to recapitulate human stroma interactions and may be providing confounding data for translation of new therapies.
My long-term research goal is to utilize 3D cell culture to provide better translational data for new stromal targeting therapies for PDAC. The proposed research is to develop and utilize MS methods to understand protein and metabolism changes in 3D cell culture models of PDAC and to characterize and understand how tumor architecture and the presence of tumor stroma affects drug distribution.
Background: Pancreatic ductal adenocarcinoma (PDAC), the most common type of pancreatic cancer, is a death sentence, with survival statistics that differ drastically from other cancer types. In 2014, the Cancer Research UK Cancer Survival Group reported a 5-year survival of 54% and 1-year survival of 70% for all cancers types, while pancreatic cancer reported a 3% 5-year survival and a 21% 1-year survival. PDAC remains one of the hardest to treat cancers because most patients are diagnosed at a late metastatic stage, with only 20% of patients eligible for surgical resection. Additionally, treatment options are often ineffective. Currently, gemcitabine, a cytosine analog and the standard of care, offers average survival of only 6 months. In the past 40 years, the 5-year relative survival rate has increased from 3% to 7% despite persistence in PDAC research. As you increase in PDAC grade, histologically the duct structure disintegrates and becomes infiltrated with normal cells into disorganized tumor architecture. Recent attention in pancreatic cancer has turned to understanding interactions between these infiltrating cells and the disorganized tumor architecture. The cancer cells are able to recruit these normal cells, which then become activated to secrete extracellular matrix (ECM) proteins and other signaling molecules that make up the tumor stroma. One of the main cells recruited in pancreatic cancer are pancreatic stellate cells (PSCs), which are normally present in the pancreas in a quiescent state. Upon recruitment into the tumor, they become activated by tumor cytokines and deposit excess ECM. Originally, it was thought infiltration of PSCs was the body’s way of fighting off the tumor. Current literature supports the idea tumor stroma actually be both protecting and fighting the tumor. Pancreatic cancer is notorious for its fibrotic and poorly perfused vasculature, caused by the activation of PSCs. This excess ECM provides a shell of protection around the tumor preventing drug penetration and creates a hypoxic microenvironment that activates chemoresistance cell signaling and supports an altered tumor metabolism. Manipulation of the stromal barrier seems to hold the most promise for new effective treatments for pancreatic cancer.
SHG as readout for prognosis for improving histology; what is happening in these collagen regions? Can MSI be used to understand biological basis or act as
SHG is an optical signal produced by fibrillar collagen. The ratio of the forward-to-backward emitted SHG signals (F/B) is sensitive to changes in structure of individual collagen fibers. F/B from excised primary tumor tissue was measured in a retrospective study of LNN breast cancer patients who had received no adjuvant systemic therapy and related to metastasis-free survival (MFS) and overall survival (OS) rates.
Metabolism as a readout for chemoresponse
clinically heterogeneous disease, which necessitates a variety of treatments and leads to different outcomes.
- control, drug treated- OMI Index - single cell resolution,
Expanding studies for clinical significance:
If NADH and FAD are readouts of chemoresponse, can we identify these metabolite signatures in patients
FFPE - can we get metabolism readout for prognosis and chemoresponse - accurate records of drug treatment with patient history