Nuclear COMMD1 Is Associated with Cisplatin Sensitivity in Ovarian Cancer

Copper metabolism MURR1 domain 1 (COMMD1) protein is a multifunctional protein, and its expression has been correlated with patients’ survival in different types of cancer. In vitro studies revealed that COMMD1 plays a role in sensitizing cancer cell lines to cisplatin, however, the mechanism and its role in platinum sensitivity in cancer has yet to be established. We evaluated the role of COMMD1 in cisplatin sensitivity in A2780 ovarian cancer cells and the relation between COMMD1 expression and response to platinum-based therapy in advanced stage high-grade serous ovarian cancer (HGSOC) patients. We found that elevation of nuclear COMMD1 expression sensitized A2780 ovarian cancer cells to cisplatin-mediated cytotoxicity. This was accompanied by a more effective G₂/M checkpoint, and decreased protein expression of the DNA repair gene BRCA1, and the apoptosis inhibitor BCL2. Furthermore, COMMD1 expression was immunohistochemically analyzed in two tissue micro-arrays (TMAs), representing a historical cohort and a randomized clinical trial-based cohort of advanced stage HGSOC tumor specimens. Expression of COMMD1 was observed in all ovarian cancer samples, however, specifically nuclear expression of COMMD1 was only observed in a subset of ovarian cancers. In our historical cohort, nuclear COMMD1 expression was associated with an improved response to chemotherapy (OR = 0.167; P = 0.038), although this association could not be confirmed in the second cohort, likely due to sample size. Taken together, these results suggest that nuclear expression of COMMD1 sensitize ovarian cancer to cisplatin, possibly by modulating the G₂/M checkpoint and through controlling expression of genes involved in DNA repair and apoptosis.

Breaking the DNA damage response to improve cervical cancer treatment

Every year, cervical cancer affects ∼500,000 women worldwide, and ∼275,000 patients die of this disease. The addition of platin-based chemotherapy to primary radiotherapy has increased 5-year survival of advanced-stage cervical cancer patients, which is, however, still only 66%. One of the factors thought to contribute to treatment failure is the ability of tumor cells to repair chemoradiotherapy-induced DNA damage. Therefore, sensitization of tumor cells for chemoradiotherapy via inhibition of the DNA damage response (DDR) as a novel strategy to improve therapy effect, is currently studied pre-clinically as well as in the clinic. Almost invariably, cervical carcinogenesis involves infection with the human papillomavirus (HPV), which inactivates part of the DNA damage response. This HPV-mediated partial inactivation of the DDR presents therapeutic targeting of the residual DDR as an interesting approach to achieve chemoradio-sensitization for cervical cancer. How the DDR can be most efficiently targeted, however, remains unclear. The fact that cisplatin and radiotherapy activate multiple signaling axes within the DDR further complicates a rational choice of therapeutic targets within the DDR. In this review, we provide an overview of the current preclinical and clinical knowledge about targeting the DDR in cervical cancer.

Abstract 2417: Predictive and therapeutic impact of DNA damage response activation in locally advanced cervical cancer patients

Recent advances in improving outcome of locally advanced cervical cancer (LACC) were made by addition of cisplatin to radiotherapy. However, total 5-year survival rates are still ∼66%, underscoring the need for new therapy strategies.

Current therapeutic strategies in cervical cancer consist of cisplatin and radiotherapy, which exert their anti-cancer effects by inducing high levels of DNA lesions including DNA double strand breaks (DSBs), with the aim to induce cell death in tumor cells.

However, tumor cells can respond to these therapy-induced DNA lesions by activation of the DNA damage response (DDR). The DDR is a complex signalling network, consisting of multiple kinases and transcriptional programs that function in parallel to arrest ongoing cell cycle progression, which allows time for DNA repair. Effective DNA repair may thus counteracts therapy-induced cancer cell death.

Cervical cancers already have a partial dysfunction of the DDR due to frequent, human papilloma virus (HPV) infection. As a result, HPV-infected cervical tumors are thought to rely heavily on remaining DDR activity for their survival. We therefore hypothesize that the residual DDR activity may provide an ‘Achilles heel’ which could be exploited therapeutically using specific DDR inhibitors, to increase tumor cell sensitivity to cisplatin and ionizing radiation.

Firstly, we examined the expression and activation status of the key DDR components ATM, Chk2, ATR, Chk1, DNA-PK and MK2 in 375 cervical cancer patients using immunohistochemistry. We found that these DDR components were all abundantly expressed in cervical cancer tissues, underscoring the availability of these components for targeting by DDR inhibitors.

Subsequently, we tested chemo- or radiosensitization of specific chemical inhibitors against ATM (KU-55933), ATR (NU-6027), DNA-PK (KU-0060648), Chk1/2 (AZD7762) and MK2 (MK2-inhibitor III) using HPV-positive cervical cancer cell lines HeLa and SiHa. MTT-assay analyses showed that ATR, Chk1/2 and DNA-PK inhibition, sensitized cervical cancer cells to cisplatin. In contrast, clonogenic survival assays revealed that inhibition of ATM, DNA-PK and Chk1/2 caused radiosensitization. In order to uncover how DDR inactivation is most effective in a combined chemo-radiotherapy setting, we therefore optimised an in vitro ‘combination therapy survival assay’ reflecting the different DNA lesions given in clinical LACC therapy. We showed that targeting of ATM, ATR and Chk1/2 caused effective chemo-radiosensitization of cervical cancer cells.

Our data show that DDR components are abundantly expressed in cervical cancer. Furthermore, we show that targeting of individual DDR kinases has differential effects on chemo- or radiotherapy sensitivity. Finally, we show that ATM, ATR and Chk1/2 inhibition are promising strategies to further improve the efficacy of platinum-based chemoradiation.

Citation Format: Hylke W. Wieringa, Marieke Everts, G.Bea A. Wisman, Ate G.J. van der Zee, Elisabeth G.E. de Vries, Marcel A.T.M. van Vugt. Predictive and therapeutic impact of DNA damage response activation in locally advanced cervical cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2417. doi:10.1158/1538-7445.AM2014-2417

The role of ATM and 53BP1 as predictive markers in cervical cancer

Treatment of advanced-stage cervical cancers with (chemo)radiation causes cytotoxicity through induction of high levels of DNA damage. Tumour cells respond to DNA damage by activation of the 'DNA damage response' (DDR), which induces DNA repair and may counteract chemoradiation efficacy. Here, we investigated DDR components as potential therapeutic targets and verified the predictive and prognostic value of DDR activation in patients with cervical cancer treated with (chemo)radiation. In a panel of cervical cancer cell lines, inactivation of ataxia telangiectasia mutated (ATM) or its substrate p53-binding protein-1 (53BP1) clearly gave rise to cell cycle defects in response to irradiation. Concordantly, clonogenic survival analysis revealed that ATM inhibition, but not 53BP1 depletion, strongly radiosensitised cervical cancer cells. In contrast, ATM inhibition did not radiosensitise non-transformed epithelial cells or non-transformed BJ fibroblasts. Interestingly, high levels of active ATM prior to irradiation were related with increased radioresistance. To test whether active ATM in tumours prior to treatment also resulted in resistance to therapy, immunohistochemistry was performed on tumour material of patients with advanced-stage cervical cancer (n = 375) treated with (chemo)radiation. High levels of phosphorylated (p-)ATM [p = 0.006, hazard ratio (HR) = 1.817] were related to poor locoregional disease-free survival. Furthermore, high levels of p-ATM predicted shorter disease-specific survival (p = 0.038, HR = 1.418). The presence of phosphorylated 53BP1 was associated with p-ATM (p = 0.001, odds ratio = 2.206) but was not related to any clinicopathological features or survival. In conclusion, both our in vitro and patient-related findings indicate a protective role for ATM in response to (chemo)radiation in cervical cancer and point at ATM inhibition as a possible means to improve the efficacy of (chemo)radiation.

Abstract 4171: The role of ATM and 53BP1 as predictive markers and therapeutic targets in advanced stage cervical cancer

Chemoradiation is the standard of care for advanced stage cervical cancer patients and induces cytotoxicity by inducing high levels of DNA breaks in the tumor. The ability of tumor cells to repair therapy-induced DNA damage may counteract the effects of chemoradiation. The pathway responsible for DNA double strand break repair is called the ‘DNA damage response’.

In vitro we observed robust radiation-induced G1 and G2 cell cycle arrests in cervical cancer cell lines, despite the expression of HPV oncogenes, which impact the DNA damage response through rapid p53 degradation. Moreover, the DNA damage checkpoint protein ATM and its substrate 53BP1 are required for proper induction of cell cycle checkpoint arrests. Yet, when long-term survival effects were measured, inhibition of ATM, but not 53BP1, strongly sensitized cervical cancer cells to irradiation. To validate the putative role of ATM and 53BP1 in advanced stage cervical cancer we investigated presence and activity of ATM as well as 53BP1 in relation to response-to-treatment in a large, well documented, series of advanced stage cervical cancer patients (n=375). We found that high levels of ATM were related to poor response to chemoradiation (P=0.013). Importantly, high phosho-ATM immunostaining, reflecting active ATM, predicted poor responses to chemoradiation even better (P=0.004). In addition, high phospho-ATM levels predicted shorter disease-specific survival (P=0.020).

Although presence of phosphorylated 53BP1 did relate to phospho-ATM (P=0.001), it was not significantly related to any clinicopathological features or survival.

Combined, our data suggest the prognostic value of ATM signaling for responses to chemoradiation and point at ATM inhibition as a potential therapeutic target to increase treatment efficacy in advanced stage cervical cancers.

Acknowledgements

This research is supported by the Dutch Cancer Society (RUG 2007-3719) and the Netherlands Organization for Scientific Research (NWO-VENI 916.76.062).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4171. doi:10.1158/1538-7445.AM2011-4171