bims-istrec Biomed News
on Integrated stress response in cancer
Issue of 2022‒01‒30
four papers selected by
Vincenzo Ciminale’s Lab
Istituto Oncologico Veneto

  1. Mol Biol (Mosk). 2022 Jan-Feb;56(1):56(1): 135-146
      The endoplasmic reticulum (ER) stress inducers dithiothreitol (DTT) and sodium selenite (SS) were tested for effect on expression of ER selenoproteins and apoptosis markers in MCF7 breast adenocarcinoma cells. DTT used at 1 or 5 mM did not affect the survival of MCF7 cells. Based on the real-time PCR data and the protein expression levels of ER stress markers, ER stress was assumed to evolve along an adaptation pathway in MCF7 cells treated with 1 or 5 mM DTT, involving mainly the transcription factors IRE1 and ATF6 and the selenoproteins SELS, SELK, SELT, SELM, and SELN. Cell treatment with 0.01 μM SS decreases the mRNA levels of all genes examined. When the SS concentration was increased to 0.1 μM, an increase in expression was observed for key ER stress genes and apoptosis markers, including CHOP, GADD34, PUMA, BIM, ATF4, sXBP, uXBP, AKT1, BAX, and BAK. Higher SS concentrations were assumed to trigger the unfolded protein response (UPR) via a proapoptic signaling pathway involving PERK and an alternative IRE1 signaling pathway. Used at 1 μM, SS increased the mRNA levels of apoptosis markers, upregulated expression of a spliced form of XBP1, and substantially decreased the cell survival. SS (1 μM) was assumed to trigger apoptosis in MCF7 cells. The results indicate that both adaptive and proapoptic UPR signaling pathways are activated in cells, depending on the nature and concentration of the ER stress inducer.
    Keywords:  apoptosis; dithiothreitol; endoplasmic reticulum stress; selenoproteins; sodium selenite
  2. Evid Based Complement Alternat Med. 2022 ;2022 4451178
      Tumor protein D52-like 2 or simply TPD52L2 belongs to the TPD52 family which has been implicated in a variety of human carcinomas. However, the TPD52L2 function in the gastric carcinoma oxaliplatin (OXA) resistance remains elusive. The main objective of this study is to evaluate the TPD52L2 effect in OXA-resistant gastric carcinoma cells in vitro. Oxaliplatin-resistant gastric carcinoma cells were generated in MGC-803 and SGC-7901 cells. siRNA-mediated knockdown of TPD52L2 was investigated in OXA-resistant MGC-803-OXA and SGC-7901-OXA cells. qRT-PCR was performed to assess the expression level of TPD52L2 mRNA. TPD52L2 protein expression level, apoptosis, and endoplasmic reticulum (ER) stress-associated proteins were identified via immunoblotting analysis. MTT assay was conducted for the evaluation of cell viability, while colony-forming activity was carried out via crystal violet staining. SGC-7901-OXA and MGC-803-OXA cells were found to be more resistant to OXA, as compared to the parental cell lines. The expression of TPD52L2 was found to be upregulated in OXA-resistant cells. Knockdown of TPD52L2 suppressed cell colony-forming potency, cell growth, and development in OXA-resistant cells. TPD52L2 knockdown also enhanced the PARP and caspase-3 cleavage. ER-associated proteins such as PERK, GRP78, CHOP, and IRE1α were found to be elevated in TPD52L2 knockdown cells. ER stress might be involved in TPD52L2 knockdown-induced apoptosis in OXA-resistant gastric carcinoma cells.
  3. J Cancer. 2022 ;13(2): 554-564
      Lung cancer is the most common malignancy worldwide, and LUAD is the primary type of lung cancer. Recently, the POU transcription factor family has been associated with the development of multicancer, especially lung cancer. However, the relationship between POU domain class Ⅳ transcription factor Ⅲ (POU4F3) and lung cancer remains unknown. We detected the expression of POU4F3 in human LUAD and adjacent tissues with immunohistochemical staining, and we found that POU4F3 was expressed less in LUAD tissues compared with adjacent tissues. Patients with higher POU4F3 expression have more prolonged overall survival. We then constructed SPCA1 and A549 cells with stable overexpression or inhibition of POU4F3. We found that overexpressed POU4F3 suppressed LUAD cell proliferation in vitro and in vivo, according to CCK-8, colony formation, and xenograft assays. LUAD cell apoptosis was suppressed by POU4F3 overexpression based on Flow cytometry. The downregulation of POU4F3 yielded the opposite patterns. Next, we explored the possible mechanisms through which POU4F3 promoted the apoptosis of LUAD cells. Western blotting suggested that overexpression of POU4F3 significantly increased protein expression levels of the PERK/eIF2α/ATF4/CHOP and IRE1α/XBP1s pathways of ERS, while POU4F3 absence reversed the expressions of the above essential proteins in ERS pathways in SPCA1 and A549 cells. However, we found that PERK inhibitor but not IRE1 inhibitor can reverse the effect of POU4F3 overexpression on apoptosis. This study indicated that POU4F3 may work as a tumor suppressor in LUAD via regulating the PERK/eIF2α/ATF4/CHOP pathway. We made it possible to develop POU4F3 as a diagnostic, therapeutic, and prognostic target of LUAD.
    Keywords:  Apoptosis; ERS; LUAD; POU4F3; Proliferation
  4. J Cancer. 2022 ;13(2): 669-680
      PERK is one of the transmembrane sensors of unfolded protein response (UPR) triggered by ER stress. In this study, we evaluated the role of PERK in the sensitivity of hepatocellular carcinoma (HCC) cells to high linear energy transfer (LET) carbon ions (CI). We found that CI irradiation could induce ER stress in HCC cells. On the one hand, PERK promoted autophagy via regulating ATF4 expression; on the other hand, PERK regulated p53 expression, and the latter either induced autophagy through up-regulating DRAM, or directly promoting apoptosis through the mitochondrial pathway or facilitating ferroptosis via down-regulating SLC7A11 (the extrinsic pathway), but independent of GPX4 (the intrinsic pathway). These factors jointly determined the sensitivity of HCC cells to high-LET CI radiation. Inhibiting TP53 directly increased cellular radioresistance definitely. Moreover, the death of HepG2 (TP53 wild type) cells induced by high-LET CI irradiation combined with sorafenib treatment might be caused by a mixed-type regulated cell death (RCD) including both apoptosis and ferroptosis, suggesting that apoptosis and ferroptosis are synergetic cell death modes regulated by TP53, which is one of the reasons why the sensitivity of HepG2 cells is higher than that of Hep3B (TP53 null type) and PLC/PRF5 (TP53 mutated type) cells. Therefore, our work might shed light on the potential therapeutic implication of CI radiotherapy combined with PERK targeted clinical drugs to implement personalized and precise treatment of HCCs.
    Keywords:  ER stress; PERK; autophagy; carbon ion; ferroptosis