RIP1K and RIP3K provoked by shikonin induce cell cycle arrest in the triple negative breast cancer cell line, MDA-MB-468: necroptosis as a desperate programmed suicide pathway

Abstract

Resistance to cell death and reprogramming of metabolism are important in neoplastic cells. Increased resistance to apoptosis and recurrence of tumors are the major roadblocks to effective treatment of triple negative breast cancer. It has been thought that execution of necroptosis involves ROS generation and mitochondrial dysfunction in malignant cells. In this study, the effect of shikonin, an active substance from the dried root of Lithospermum erythrorhizon, on the induction of necroptosis or apoptosis, via RIP1K-RIP3K expressions has been examined in the triple negative breast cancer cell line. The expression levels of RIP1K and RIP3K, caspase-3 and caspase-8 activities, the levels of ROS, and mitochondrial membrane potential have been studied in the shikonin-treated MDA-MB-468 cell line. An increase in the ROS levels and a reduction in mitochondrial membrane potential have been observed in the shikonin-treated cells. Cell death has mainly occurred through necroptosis with a significant increase in the RIP1K and RIP3K expressions, and characteristic morphological changes have been observed. In the presence of Nec-1, caspase-3 mediating apoptosis has occurred in the shikonin-treated cells. The current findings have revealed that shikonin provoked mitochondrial ROS production in the triple negative breast cancer cell line, which works as a double-edged executioner's ax in the execution of necroptosis or apoptosis. The main route of cell death induced by shikonin is RIP1K-RIP3K-mediated necroptosis, but in the presence of Nec-1, apoptosis has prevailed. The present results shed a new light on the possible treatment of drug-resistant triple negative breast cancer.

Shikonin induces mitochondria-mediated apoptosis and enhances chemotherapeutic sensitivity of gastric cancer through reactive oxygen species

“…SHK is a naphthoquinone extracted from Chinese herbal medicine plant and is considered to be safe due to its long history use in Chinese traditional medicine. Recent studies confirmed its anti-tumour effects in osteosarcoma46, leukaemia39, colon cancer14, breast cancer16 and glioma19. In this study, we found that SHK suppresses proliferation and induces death in SGC-7901 and BGC-823 gastric cancer cells in dose- and time-dependent manners.…”

“…Necroptosis is a programmed form of necrosis and SHK has been reported as a necroptosis inducer in previous studies161838. Necroptosis is typically inhibited by the blockade of RIPK1.…”

“…When caspase 8 is blocked, RIPK1 and RIPK3 become phosphorylated and trigger necroptosis52. Recent studies reported that RIPK1 mediates necroptosis induced by SHK in osteosarcoma, breast cancer and glioma161819. According to previous report of Lee et al ., SHK induced necrosis at 6 h and apoptosis at 24 h of gastric cancer cell AGS, which was time-dependent37.…”

“…SHK also has a cytotoxic effect on MDR cell lines and enhances chemotherapeutic sensitivity. It enhances cisplatin-induced colon cancer cell apoptosis, synergistically kills glioblastoma cells in combination with erlotinib and induces cell cycle arrest in triple negative breast cells14151617. Furthermore, SHK has anti-tumour effects by inducing receptor-interacting protein 1 (RIPK1)-dependent necroptosis1819.…”

<p>Pharmacological Inhibition of Necroptosis Promotes Human Breast Cancer Cell Proliferation and Metastasis</p>

“…22 Previous studies have reported necroptosis as a desperate programmed suicide pathway in breast cancer MDA-MB-468 cells. 23 In fact, necroptosis signaling has been reported to serve as a potent target, and extracts from traditional Chinese medicine have been shown to confer therapeutic efficacy against breast cancer by specifically inducing necroptotic cell death. 24,25 A Smac mimetic also protected against breast cancer via inducing caspase-independent necroptosis.…”