Pancreatic adenocarcinoma (PC) is a disease typified by resistance to therapy and poor outcomes. There is a pressing need to discover new therapies and determine whether existing therapies will be ineffective in certain patients. Recently, the addition of nab-paclitaxel (Abraxane(r)) to gemcitabine has been shown to improve response rates and survival in PC, at the expense of added toxicity. Nab-paclitaxel is an albumin-bound chemotherapeutic which has been hypothesized to enter the cell through caveolae/gp60-mediated albumin endocytosis. Caveolae are 50-100 nM membrane invaginations responsible for endocytosis, cholesterol homeostasis, and signal transduction. Caveolin-1 (Cav-1) is the principal structural component of caveolae, and genetic knockdown of Cav-1 ablates caveolae. Our preliminary data indicate that Cav-1 is over-expressed and associated with poor prognosis in PC, and confers oncogenic properties including migration, invasion, and resistance to therapy. Our data also suggest that Cav-1 expression is important for intracellular transport of albumin and nab-paclitaxel into PC cells. Thus, we hypothesize that Cav-1 levels regulate entry and can predict response to nab-paclitaxel. In addition, we seek to improve upon nab-paclitaxel by identifying other strategies which increase nab-paclitaxel efficacy and by testing novel albumin-conjugated chemotherapeutics.
Our specific aims i nclude: (1) To determine whether Cav-1 expression mediates albumin uptake and response to nab-paclitaxel; (2) To determine whether Cav-1 expression mediates response to novel albumin-conjugated chemotherapeutics; and (3) To test strategies to improve response to nab-paclitaxel. We will test whether Cav-1 levels affect response to nab-paclitaxel in a panel of PC cell lines through analysis of albumin and nab- paclitaxel uptake, cytotoxicity assays, and activation of apoptotic pathways. We will extend these studies in vivo to assess whether loss of Cav-1 alters response to nab-paclitaxel using patient-derived xenograft and autochthonous mouse models of PC. In addition, we will determine whether Cav-1 levels in tumor, stroma, and blood predict response to nab-paclitaxel in samples obtained from patients with PC receiving nab- paclitaxel. Furthermore, we will test novel albumin-chemotherapy conjugates that appear superior to nab- paclitaxel and determine whether Cav-1 levels also regulate their response. Lastly, we will test other strategies to increase Cav-1 expression in order to further sensitize cells to nab-paclitaxel If successful, these studies will establish that Cav-1 is important for albumin entry in PC tumor cells and dictates response to albumin- bound chemotherapies. Furthermore, these studies could allow personalization of therapy by predicting which tumors are likely to benefit from nab-paclitaxel, by stratifying therapy based on Cav-1 expression. Finally, these studies are designed to be the first to refine an existing therapy in PC through targeting of the Cav-1/caveolae-dependent albumin endocytic pathway.

Public Health Relevance

Pancreatic cancer is a highly lethal cancer typified by poor treatment outcomes, for which we need new treatments and ways to select which patients will derive the most benefit from existing therapies. Abraxane(r) is a chemotherapy drug that has recently shown significant improvement in patients with pancreatic cancer. We have identified a protein, caveolin-1 (or Cav-1), that is abundant in pancreatic cancer cells, important for their growth, and may be important for entry and response of Abraxane(r) into tumor cells, thus serving as a potential biomarker to allow for personalization of therapy and a target for further research.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
7R01CA198128-06
Application #
10332467
Study Section
Developmental Therapeutics Study Section (DT)
Program Officer
Fu, Yali
Project Start
2016-04-01
Project End
2021-03-31
Budget Start
2021-01-01
Budget End
2021-03-31
Support Year
6
Fiscal Year
2020
Total Cost
Indirect Cost
Name
Beckman Research Institute/City of Hope
Department
Type
DUNS #
027176833
City
Duarte
State
CA
Country
United States
Zip Code
91010