ATR and p-ATR are emerging prognostic biomarkers and DNA damage response targets in ovarian cancer

Abstract

Background: Although ataxia-telangiectasia and Rad3 related (ATR) has an established role in the DNA damage response of various cancers, its clinical and prognostic significance in ovarian cancer remains largely unknown. The aims of this study were to assess the expression, function, and clinical prognostic relationship of ATR and phospho-ATR ser428 (p-ATR) in ovarian cancer. Methods: We confirmed ATR and p-ATR expression by immunohistochemistry (IHC) in a unique ovarian cancer tissue microarray constructed of paired primary, recurrent, and metastatic tumor tissues from 26 individual patients. ATR-specific small interfering RNA (siRNA) and ATR inhibitor VE-822 were applied to determine the effects of ATR inhibition on ovarian cancer cell proliferation, apoptosis, and DNA damage. ATR expression and the associated proteins of the ATR/Chk1 pathway in ovarian cancer cell lines were evaluated by Western blotting. The clonogenicity was also examined using clonogenic assays. A three dimensional (3D) cell culture model was performed to mimic the in vivo ovarian cancer environment to further validate the effects of ATR inhibition on ovarian cancer cells. Results: We show recurrent ovarian cancer tissues express higher levels of ATR and p-ATR than their patient-matched primary tumor counterparts. Additionally, higher expression of p-ATR correlates with decreased survival in ovarian cancer patients. Treatment of ovarian cancer cells with ATR specific siRNA or ATR inhibitor VE-822 led to significant apoptosis and inhibition of cellular proliferation, with reduced phosphorylation of Chk1 (p-Chk1), Cdc25c (p-Cdc25c), Cdc2 (p-Cdc2), and increased expression of cleaved PARP and γH2AX. Inhibition of ATR also suppressed clonogenicity and spheroid growth of ovarian cancer cells. Conclusion: Our results support the ATR and p-ATR pathway as a prognostic biomarker, and targeting the ATR machinery is an emerging therapeutic approach in the treatment of ovarian cancer.

Molecular Features in Lymphatic Metastases Reflect the Metastasis Mechanism of Lymph Nodes With Non-Small-Cell Lung Cancers

“…Importantly, ATR was regarded as the primary sensor of oncogenes that triggered replication stress and DNA damage. Previous studies revealed that ATR was likely to be a prognostic biomarker for some solid tumors (Feng et al, 2020), but the result was contradictory found by Zighelboim et al (2009). Kashyap et al (2020) found that ATR presented with a low transcriptional level in 76% of uveal melanoma patients who were significant with metastasis (p = 0.046).…”

Hydrogen Sulfide Biology and Its Role in Cancer

“…ATRCHK1 pathway activation is increased in various tumor types [ 198 , 199 ]. Furthermore, elevated ATR protein, phospho-ATR, and phospho-CHK1 expression are associated with a poor prognosis in bladder, ovarian, and breast cancers [ 199 , 200 , 201 ]. Because the ATR kinase controls H 2 S concentrations, increases in ATR and CHK1 may increase H 2 S production.…”

Molecular Functions of Hydrogen Sulfide in Cancer

“…Low cellular H 2 S concentrations increased ATR kinase activity measured by CHK1 phosphorylation, while high H 2 S concentrations suppressed ATR ser-435 phosphorylation, a marker of ATR kinase activation [ 4 , 96 ]. Increased ATR-CHK1 pathway activity has been identified in several tumor types [ 97 , 98 , 99 , 100 ]. Additionally, increased ATR protein, phospho-ATR, and phospho-CHK1 expression confers a poor prognosis in breast, bladder, and ovarian cancers [ 98 , 99 , 100 ].…”

“…Increased ATR-CHK1 pathway activity has been identified in several tumor types [ 97 , 98 , 99 , 100 ]. Additionally, increased ATR protein, phospho-ATR, and phospho-CHK1 expression confers a poor prognosis in breast, bladder, and ovarian cancers [ 98 , 99 , 100 ]. As the ATR kinase regulates H 2 S concentrations, it is possible that increases in ATR and CHK1 result in increased H 2 S synthesis.…”