Abstract 4327: Nek6 and Hif-1α cooperate with the cytoskeletal gateway of drug resistance to drive outcome in serous ovarian cancer

Abstract

Hypoxia selects the most aggressive and drug-resistant clones in solid malignancies. One of the pivotal transcription factors induced by hypoxia is Hif-1α. However, in serous ovarian cancer (SEOC), Hif-1α expression is not a prognostic biomarker. This study aims to assess the hypothesis that the serine-threonine kinase Nek6 functions as a downstream effector cooperating with Hif-1α in driving ovarian cancer aggressiveness. Nek6 was overexpressed and Hif-1α was silenced in A2780 cells. Nek6 was also stably silenced in Hey cells. The dependence of Nek6 expression on Hif-1α was assayed as a function of hypoxic growth conditions. Nek6 interaction with the cytoskeletal gateway of drug resistance was investigated with far western blot. The co-expression of NEK6, HIF1A, TUBB3 and GBP1 transcripts was quantified with qPCR in two cohorts of SEOC patients (346 locally treated patients and 344 from the TCGA dataset). Nek6 expression is induced by hypoxia in a Hif-1α dependent fashion. Nek6 directly interacts with GBP-1, thus being a component of the cytoskeletal gateway of drug resistance. Nek6 overexpression increases and silencing decreases the anchorage-independent growth of cultured cells. In SEOC patients, NEK6 expression is significantly correlated with HIF1A. Co-expression of NEK6, HIF1A, TUBB3 and GBP1 transcripts identifies a subset of SEOC patients characterized by poor outcome and drug resistance. This study demonstrates the functional relevance of Nek6 in the context of the adaptive response to hypoxia in SEOC. This finding may help identify a sub-population of patients at high risk of relapse to standard first-line chemotherapy. Citation Format: Marta De Donato, Mara Fanelli, Marisa Mariani, Giuseppina Raspaglio, Deep Pandya, Shiquan He, Paul Fiedler, Marco Petrillo, Giovanni Scambia, Cristiano Ferlini. Nek6 and Hif-1α cooperate with the cytoskeletal gateway of drug resistance to drive outcome in serous ovarian cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4327. doi:10.1158/1538-7445.AM2015-4327

Identification and antitumor activity of a novel inhibitor of the NIMA-related kinase NEK6

“…Although this is not an unusual finding, since synergism and antagonism can be different at different dose levels 47 , it certainly requirer further investigation to properly identify the best combination drug schedule. Results from the combination studies are in line with our previous findings demonstrating that stable NEK6 silencing in ovarian cancer cells produced a modest but significant increase of cisplatin and paclitaxel sensitivity, while a stable overexpression slightly increased drug resistance 11 .…”

“…NEK6 is also directly phosphorylated by CHK1 and CHK2, thus being identified as a novel direct target of the DNA damage checkpoint 10 . Notably, overexpression of NEK6 has been linked to many human diseases including liver, breast, lung, stomach, colon, larynx, ovary and prostate cancer 11 – 16 , and in line with these findings, we also recently showed that NEK6 is an independent unfavorable prognostic marker in ovarian cancer 11 . Taken together these data indicate that although the precise role in tumorigenesis remains unknown, NEK6 actually represents an attractive target for new anticancer therapies and inhibitors of NEK6 could be powerful compounds in the clinical setting.…”

Checking NEKs: Overcoming a Bottleneck in Human Diseases

“…A bioinformatic analysis showed the presence of HRE (Hypoxia Responsive Elements) motifs in 5 and 3 UTR of the NEK6 gene, which may be important for NEK6 regulation by HIF-1α. Additionally, in two groups of patients, concomitant expression of HIF1A and NEK6 was detected [147]. These data show that NEK6 can be regulated by HIF-1α in hypoxic conditions in serous epithelial ovarian cancer and may also be related to resistance to chemotherapeutic treatment.…”

“…In recent years, altered expression and activity of NEK6 were associated with several types of cancer, such as liver [139], prostate [140], gastric [141][142][143], colorectal [144,145], breast [146], serous epithelial ovarian [147], thyroid [148], and retinoblastoma cancers [149]. In addition, inflammation-based diseases, such as ulcerative colitis, have also been linked to NEK6 [28].…”

“…Evidence suggests that NEK6 is a downstream target of HIF-1α in ovarian cancer. Donato et al (2015) showed that HIF-1α knockdown reduces the expression of NEK6, and hypoxic conditions were shown to increase HIF-1α and NEK6 in ovarian cancer cells. A bioinformatic analysis showed the presence of HRE (Hypoxia Responsive Elements) motifs in 5 and 3 UTR of the NEK6 gene, which may be important for NEK6 regulation by HIF-1α.…”