Abstract
Efforts to develop targetable molecular bases for drug resistance for pancreatic ductal adenocarcinoma (PDAC) have been equivocally successful. Using RNA-seq and ingenuity pathway analysis we identified that the superpathway of cholesterol biosynthesis is upregulated in gemcitabine resistant (gemR) tumors using a unique PDAC PDX model with resistance to gemcitabine acquired in vivo. Analysis of additional in vitro and in vivo gemR PDAC models showed that HMG-CoA synthase 2 (HMGCS2), an enzyme involved in cholesterol biosynthesis and rate limiting in ketogenesis, is overexpressed in these models. Mechanistic data demonstrate the novel findings that HMGCS2 contributes to gemR and confers metastatic properties in PDAC models, and that HMGCS2 is BRD4 dependent. Further, BET inhibitor JQ1 decreases levels of HMGCS2, sensitizes PDAC cells to gemcitabine, and a combination of gemcitabine and JQ1 induced regressions of gemR tumors in vivo. Our data suggest that decreasing HMGCS2 may reverse gemR, and that HMGCS2 represents a useful therapeutic target for treating gemcitabine resistant PDAC.
| Original language | English |
|---|---|
| Article number | 216919 |
| Journal | Cancer Letters |
| Volume | 592 |
| DOIs | |
| State | Published - Jun 28 2024 |
Bibliographical note
Publisher Copyright:© 2024 Elsevier B.V.
Funding
Four-week old female SCID CB 17\u2212/\u2212 mice were purchased from Taconic Farms (MA, USA) or Charles River (MA, USA) and housed in the UAB Research Support Building in the AAALAC accredited vivarium. Development and characterization of gemcitabine resistant PDAC PDXs have been previously published [10]. All mice received 100 mg/kg gemcitabine weekly until the combination study began. The combination regimen of JQ1 + gemcitabine began when tumor volumes reached \u223C250 mm3 (day 29 after implantation for PA16.gemR tumors and day 49 for PA10.gemR tumors). When tumors reached \u223C250 mm3, mice bearing bilateral tumors were randomized into two groups of N = 9 tumors/group for gemcitabine and JQ1 + gemcitabine treatment except PA10.gemR gemcitabine (N = 3 tumors). When combination treatment began gemcitabine only cohorts received intraperitoneal (ip) injections of vehicle (10 % DMSO in 10 % \u03B2-cyclodextrin) daily and 100 mg/kg gemcitabine weekly. The JQ1 + gemcitabine cohorts received 50 mg/kg JQ1 daily and 100 mg/kg gemcitabine weekly for 16 or 15 days for PA16.gemR or PA10.gemR tumors, respectively. Gemcitabine hydrochloride was prepared in 0.9 % saline solution and JQ1 was prepared as instructed by the manufacturer in DMSO and \u03B2-cyclodextrin. Tumor size was measured every Monday, Wednesday, and Friday using digital calipers. Tumor volume was calculated using the formula v=(\u03C0/6)xd3. Tumor tissue was harvested 24 h after the final treatment and either formalin fixed and paraffin embedded, or snap frozen in liquid nitrogen for further analysis. Tumor volumes are presented as mean \u00B1 SEM. Tumor volumes were compared using two-way analysis of variance (ANOVA) or two-tailed t-test using GraphPad Prism 9. Tumor bearing mice were randomized to cohorts, but investigators were not blinded to designated cohorts.This study was supported by the National Institutes of Health (NIH) grant R01CA208272 and O'Neal Invests grant from the Richard A. Elkus Foundation and the University of Alabama at Birmingham O'Neal Comprehensive Cancer Center (K.J.Y.). The funding source had no role in the study design, data collection, analysis and interpretation, and writing of the manuscript. This study was supported by the National Institutes of Health (NCI) grant R01CA208272 and the University of Alabama at Birmingham O\u2019Neal Comprehensive Cancer Center grant O\u2019Neal Invests (K.J.Y.). The funding source had no role in the study design, data collection, analysis and interpretation, and writing of the manuscript.
| Funders | Funder number |
|---|---|
| University of Alabama, Birmingham | |
| Department of Radiation Oncology, University of Alabama-Birmingham Comprehensive Cancer Center | |
| National Institutes of Health (NIH) | |
| Taconic Farms | |
| Richard A. Elkus Foundation | |
| National Childhood Cancer Registry – National Cancer Institute | R01CA208272 |
| National Childhood Cancer Registry – National Cancer Institute |
Keywords
- BET bromodomain inhibitor (BETi)
- Gemcitabine resistance (gemR)
- HMG-CoA synthase 2 (HMGCS2)
- Pancreatic cancer
- Patient-derived xenograft (PDX) models
ASJC Scopus subject areas
- Oncology
- Cancer Research
