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Multiomic analysis implicates OXPHOS/fatty acid oxidation as a potential druggable target in platinum-resistant high grade serous ovarian cancer

ABSTRACT: In the United States, high grade serous ovarian cancer (HGSOC) is the most lethal gynecologic malignancy and tumor response to platinum-based chemotherapy is a major determinant of clinical outcome. Although recent efforts have dramatically improved the median survival of advanced ovarian cancer, the initial treatment of the disease has remained the same. The initial therapy includes surgery and chemotherapy and the response rate is very high (85%). Unfortunately, 15% of patients do not respond to this therapy and have platinum-refractory disease. These patients have a very short survival and there is an urgent need to identify novel pharmaceutically targetable pathways to treat these patients. We generated extensive proteomic (global, phospho, ubiquitin, acetylation, pTyr) and RNASeq-based dynamic molecular profiles (+/-carboplatin at 8 and 24 hours) from HGSOC intra-patient cell line pairs (PEA1/PEA2, PEO1/PEO4, PEO14/PEO23) derived from 3 patients before and after acquiring platinum resistance. The molecular profiles revealed a multi-faceted response to carboplatin (e.g., induction of a DNA damage response, ubiquitination of ribosomal proteins, and metabolic changes), as well as novel carboplatin-induced post-translational modifications. Higher oxidative phosphorylation (OXPHOS) and fatty acid beta-oxidation (FAO) pathway expression was observed in resistant compared with sensitive cells. These expression findings were validated via metabolite profiling of cell lines and proteomic profiling of platinum sensitive and refractory HGSOC patient derived xenograft (PDX) models. Both pharmacologic inhibition and CRISPR knockout of CPT1A, which represents the rate limiting step of FAO, sensitizes HGSOC cells to platinum. The metabolic signature identified in the cell line and PDX models is correlated with survival in a previously reported proteomic analysis of HGSOC, and thus FAO is a candidate druggable pathway to overcome platinum resistance.

INSTRUMENT(S): Orbitrap Fusion

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Ovarian Serous Carcinoma Cell

DISEASE(S): Malignant Neoplasm Of Ovary

SUBMITTER: Jacob Kennedy

LAB HEAD: Amanda G Paulovich

PROVIDER: PXD020764 | Pride | 2021-12-22

REPOSITORIES: Pride

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Project description:Changes in chromatin organization are associated with resistance to anti-cancer drugs, such as platinum-based chemotherapy used as the primary treatment of ovarian cancer. We have examined the genomic distribution of chromatin accessibility changes, and relationship to gene expression changes, occurring during acquisition of resistance in vivo of high grade serous ovarian cancer (HGSOC) patients and whether this associates with genomic DNA damage distribution. Using matched chemo-sensitive and chemo-resistant ovarian cell lines isolated from HGSOC patients before and following acquisition of clinical resistance to platinum-based chemotherapy, we have examined the relationship between chromatin accessibility by ATAC-seq, platinum-DNA adduct distribution by Pt-Exo-seq and gene expression by RNA-seq. We have correlated chromatin changes between the lines at gene promoters, CpG islands, enhancer sequences and other genomic regions with changes in gene expression and platinum-DNA adduct distribution. We observe chromatin conformation differences following acquisition of platinum-resistance, with the HGSOC resistant lines clustering together, separately from their respective sensitive counterparts. Resistant lines show altered chromatin accessibility at intergenic regions, but less so at gene promoters. Super-enhancers, as defined by clusters of cis-regulatory elements, at these intergenic regions show chromatin changes that are associated with altered expression of linked genes, with enrichment for genes involved in the Fanconi anemia/BRCA DNA damage response pathway. Genome-wide distribution of platinum adducts associates with the chromatin changes and distinguish sensitive from resistant lines. Regions incurring fewer platinum-adducts showed a significant reduction in accessibility the resistant HGSOC cell line PEO4 compared to the sensitive PEO1 counterpart. Surprisingly, regions showing increased damage in PEO4 had an even greater reduction in accessibility. In the resistant line, we observe fewer adducts around gene promoters and more adducts at intergenic regions. In cell lines derived from patients following acquisition of clinical resistance to platinum-based chemotherapy, chromatin changes at super-enhancers correlate with gene expression changes in DNA repair pathways known to influence platinum sensitivity. Although cisplatin is a relatively non-specific DNA damaging agent, there are consistent differences in distribution of adducts between the matched sensitive and resistant ovarian cell lines, which is independent of the overall level of adducts formed.

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Multiomic analysis implicates OXPHOS/fatty acid oxidation as a potential druggable target in platinum-resistant high grade serous ovarian cancer

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