Silencing of B7-H4 induces intracellular oxidative stress and inhibits cell viability of breast cancer cells via downregulating PRDX3

Abstract

Breast cancer (BC) is the most common malignancy in women worldwide, accounting for 15.5% of total cancer deaths. B7-H4 belongs to the B7 family members and plays an important role in the development of a variety of cancers, while Peroxiredoxin III (PRDX3) is an antioxidant protein found in mitochondria. Aberrant expression of B7-H4 or PRDX3 has been implicated in the tumorigenesis of various cancers. However, the functional roles of B7-H4 and PRDX3 in BC and the underlying mechanisms remain unclear. In this research, we found that silencing of B7-H4 by siRNA could lead to not only cell viability inhibition but also the downregulation of PRDX3 in MCF-7 and T47D cells. In order to reveal the roles of PRDX3 in the B7-H4 pathway, we firstly transfected siRNA specifically targeting PRDX3 into MCF-7 and T47D cells, and the results showed that silencing of PRDX3 also inhibited the viability of MCF-7 and T47D cells significantly, accompanied by the increase of reactive oxygen species (ROS) levels. Then we overexpressed the expression of PRDX3 by transfecting PRDX3 expression plasmids into B7-H4 knocking-down cells of MCF-7 and T47D. The results showed that compared with the control groups (MCF-7 or T47D/siNC+pcDNA3.1 vector), cell viabilities were significantly inhibited in RNAi groups (MCF-7 or T47D/siB7-H4+pcDNA3.1 vector), and mildly inhibited in revertant groups (MCF-7 or T47D/siB7-H4+pcDNA3.1 PRDX3), meanwhile, ROS levels significantly elevated in RNAi groups and had no significant changes in revertant groups. All these results indicate t hat silencing of B7-H4 increases intracellular ROS levels and affects cell viability by modulating the expression of PRDX3 in BC cells, which may provide a potential strategy and therapeutic target for the treatment of BC.

Kinome-wide synthetic lethal screen identifies PANK4 as modulator of resistance in glioblastoma

“…In line with other studies, downregulation of the above-mentioned proteins has been linked to numerous processes in GBM, such as inhibition of cell proliferation and tumour growth (30-34, 51-53) increased apoptosis (31,32,35,51,52) and most importantly, sensitisation of GBM cells to treatment with TMZ and/or ionizing radiation (30,33,35,36,53). Similar effects have also been observed in other cancer types (41,54,55). Interestingly, we also showed that PANK4 expression is induced in TMZ-resistant GBM cells following exposure to the drug, suggesting a potential requirement for PANK4 in the response to TMZ-induced genotoxic damage.…”

“…To note, a number of metabolites can exert toxic effects and, if not promptly 'drained', can accumulate to toxic levels (39). Our proteomic analysis uncovered a marked downregulation of a host of detoxi cation proteins in response to PANK4 silencing, such as GSTP1, NQO1, PRDX3, PRDX1, ADH5, SRXN1, DHFR, GSTM2, ESD, ALDH1A1, GSTM3, MTARC2, AKR1B10, PARK7, some of which play crucial roles in cellular protection against oxidative stress in GBM (30)(31)(32)(33)(34)(35)51) and other cancers (37,38,(40)(41)(42). In line with other studies, downregulation of the above-mentioned proteins has been linked to numerous processes in GBM, such as inhibition of cell proliferation and tumour growth (30-34, 51-53) increased apoptosis (31,32,35,51,52) and most importantly, sensitisation of GBM cells to treatment with TMZ and/or ionizing radiation (30,33,35,36,53).…”

“…Importantly, numerous toxic metabolites can accumulate within the cell and, if not adequately cleared, lead to detrimental consequences, emphasising the importance for cells to rely on e cient detoxi cation systems (39). Of note, a few of the proteins we identi ed (including PARK7, PRDX1, NQO1, GSTP1, PRDX3, GSTM3, ALDH1A1, SRXN1 and GSTM2) are linked to cellular protection against oxidative stress in GBM (30)(31)(32)(33)(34)(35)(36), and other cancers (37,38,(40)(41)(42), suggesting that PANK4 may take part to the cellular detoxi cation response by preventing stress overload, including damage due to oxidative stress (Fig. 7G).…”

Kinome‐Wide Synthetic Lethal Screen Identifies PANK4 as a Modulator of Temozolomide Resistance in Glioblastoma

“…[ 39 ] Most of the downregulated proteins that were identified through our TMT‐based study following PANK4 knockdown (including PARK7, AKR1B10, PRDX1, NQO1, GSTP1, PRDX3, GSTM3, ALDH1A1, SRXN1, and GSTM2), are linked to cellular protection against oxidative stress in GBM, [ 30 , 31 , 32 , 33 , 34 , 35 , 36 ] and other types of cancers. [ 37 , 38 , 40 , 41 , 42 ] To further corroborate PANK4's involvement in the cellular response to oxidative stress, we examined the effects of PANK4 modulation on intracellular ROS levels in our resistant GBM cells. Our results showed that PANK4 silencing resulted in a surge in ROS levels, in both T98G Res and U87MG Res cells (Figure 8A ).…”

“…[ 39 ] Our proteomic analysis uncovered a marked downregulation of a host of detoxification proteins in response to PANK4 silencing, such as GSTP1, NQO1, PRDX3, PRDX1, ADH5, SRXN1, DHFR, GSTM2, ESD, ALDH1A1, GSTM3, MTARC2, AKR1B10, PARK7, some of which play crucial roles in cellular protection against oxidative stress in GBM [ 30 , 31 , 32 , 33 , 34 , 35 , 51 ] and other cancers. [ 37 , 38 , 40 , 41 , 42 ] In line with other studies, downregulation of the above‐mentioned proteins has been linked to numerous processes in GBM, such as inhibition of cell proliferation and tumor growth [ 30 , 31 , 32 , 33 , 34 , 51 , 52 , 53 ] increased apoptosis [ 31 , 32 , 35 , 51 , 52 ] and most importantly, sensitization of GBM cells to treatment with TMZ and/or ionizing radiation. [ 30 , 33 , 35 , 36 , 53 ] Similar effects have also been observed in other cancer types.…”