RESUMO
OBJECTIVE: There is an immunoreactive subtype of ovarian cancer with a favorable prognosis, but the majority of ovarian cancers have limited immune reactivity. The reason for this is poorly understood. This study aimed to approach this question by identifying prognostically relevant genes whose prognostic mRNA expression levels correlated with a genomic event. METHODS: Expression microarray and 5-year survival data on 170 ovarian tumors and aCGH data on 45 ovarian cancer cell lines were used to identify amplified/deleted genes associated with prognosis. Three immune-response genes were identified mapping to epigenetically modified chromosome 6p21.3. Genes were searched for roles in epigenetic modification, identifying KANSL1. Genome-wide association studies were searched to identify genetic variants in KANSL1 associated with altered immune profile. Sensitivity to HDAC inhibition in cell lines with KANSL1 amplification/rearrangement was studied. RESULTS: Expression of 196 genes was statistically significantly associated with survival, and expression levels correlated with copy number variations for 82 of them. Among these, 3 immune-response genes (HCP5, PSMB8, PSMB9) clustered together at epigenetically modified chromosome 6p21.3 and their expression was inversely correlated to epigenetic modification gene KANSL1. KANSL1 is amplified/rearranged in ovarian cancer, associated with lymphocyte profile, a biomarker for response to HDAC inhibition, and may drive expression of immune-response genes. CONCLUSION: This study identifies 82 genes with prognostic relevance and genomic alteration in ovarian cancer. Among these, immune-response genes have correlated expression which is associated with 5-year survival. KANSL1 may be a master gene altering immune-response gene expression at 6p21.3 and drive response to HDAC inhibitors. Future research should investigate KANSL1 and determine whether targeting it alters the immune profile of ovarian cancer and improves survival, HDAC inhibition, and/or immunotherapy response.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Biomarcadores Tumorais/genética , Carcinoma Epitelial do Ovário/terapia , Recidiva Local de Neoplasia/epidemiologia , Proteínas Nucleares/genética , Neoplasias Ovarianas/terapia , Antineoplásicos Imunológicos/farmacologia , Antineoplásicos Imunológicos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Benzamidas/farmacologia , Benzamidas/uso terapêutico , Biomarcadores Tumorais/metabolismo , Carcinoma Epitelial do Ovário/genética , Carcinoma Epitelial do Ovário/imunologia , Carcinoma Epitelial do Ovário/mortalidade , Linhagem Celular Tumoral , Quimioterapia Adjuvante/métodos , Variações do Número de Cópias de DNA , Metilação de DNA/imunologia , Conjuntos de Dados como Assunto , Intervalo Livre de Doença , Resistencia a Medicamentos Antineoplásicos/genética , Epigênese Genética/imunologia , Feminino , Seguimentos , Amplificação de Genes/imunologia , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica/imunologia , Estudo de Associação Genômica Ampla , Inibidores de Histona Desacetilases/farmacologia , Inibidores de Histona Desacetilases/uso terapêutico , Humanos , Estimativa de Kaplan-Meier , Recidiva Local de Neoplasia/genética , Recidiva Local de Neoplasia/imunologia , Recidiva Local de Neoplasia/prevenção & controle , Proteínas Nucleares/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/imunologia , Neoplasias Ovarianas/mortalidade , Ovariectomia , Prognóstico , Piridinas/farmacologia , Piridinas/uso terapêuticoRESUMO
BACKGROUND: HER2 targeted therapies including trastuzumab and more recently lapatinib have significantly improved the prognosis for HER2 positive breast cancer patients. However, resistance to these agents is a significant clinical problem. Although several mechanisms have been proposed for resistance to trastuzumab, the mechanisms of lapatinib resistance remain largely unknown. In this study we generated new models of acquired resistance to HER2 targeted therapy and investigated mechanisms of resistance using phospho-proteomic profiling. RESULTS: Long-term continuous exposure of SKBR3 cells to low dose lapatinib established a cell line, SKBR3-L, which is resistant to both lapatinib and trastuzumab. Phospho-proteomic profiling and immunoblotting revealed significant alterations in phospho-proteins involved in key signaling pathways and molecular events. In particular, phosphorylation of eukaryotic elongation factor 2 (eEF2), which inactivates eEF2, was significantly decreased in SKBR3-L cells compared to the parental SKBR3 cells. SKBR3-L cells exhibited significantly increased activity of protein phosphatase 2A (PP2A), a phosphatase that dephosphorylates eEF2. SKBR3-L cells showed increased sensitivity to PP2A inhibition, with okadaic acid, compared to SKBR3 cells. PP2A inhibition significantly enhanced response to lapatinib in both the SKBR3 and SKBR3-L cells. Furthermore, treatment of SKBR3 parental cells with the PP2A activator, FTY720, decreased sensitivity to lapatinib. The alteration in eEF2 phosphorylation, PP2A activity and sensitivity to okadaic acid were also observed in a second HER2 positive cell line model of acquired lapatinib resistance, HCC1954-L. CONCLUSIONS: Our data suggests that decreased eEF2 phosphorylation, mediated by increased PP2A activity, contributes to resistance to HER2 inhibition and may provide novel targets for therapeutic intervention in HER2 positive breast cancer which is resistant to HER2 targeted therapies.