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Pyrroline-5-carboxylate reductase (PYCR), the last enzyme in proline synthesis that converts P5C into proline, was found promoting cancer growth and inhibiting apoptosis through multiple approaches, including regulating cell cycle and redox homeostasis, and promoting growth signaling pathways. Proline is abnormally up-regulated in multiple cancers and becomes one of the critical players in the reprogramming of cancer metabolism. As the last key enzymes in proline generation, PYCRs have been the subject of many investigations, and have been demonstrated to play an indispensable role in promoting tumorigenesis and cancer progression. In this article, we will thoroughly review the recent investigations on PYCRs in cancer development., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Alternative pre-mRNA-splicing-induced post-transcriptional gene expression regulation is one of the pathways for tumors maintaining proliferation rates accompanying the malignant phenotype under stress. Here, we uncover a list of hyperacetylated proteins in the context of acutely reduced Acetyl-CoA levels under nutrient starvation. PHF5A, a component of U2 snRNPs, can be acetylated at lysine 29 in response to multiple cellular stresses, which is dependent on p300. PHF5A acetylation strengthens the interaction among U2 snRNPs and affects global pre-mRNA splicing pattern and extensive gene expression. PHF5A hyperacetylation-induced alternative splicing stabilizes KDM3A mRNA and promotes its protein expression. Pathologically, PHF5A K29 hyperacetylation and KDM3A upregulation axis are correlated with poor prognosis of colon cancer. Our findings uncover a mechanism of an anti-stress pathway through which acetylation on PHF5A promotes the cancer cells' capacity for stress resistance and consequently contributes to colon carcinogenesis., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The dysregulation of the translation elongation factor families which are responsible for reprogramming of mRNA translation has been shown to contribute to tumor progression. Here, we report that the acetylation of eukaryotic Elongation Factor 1 Alpha 1 (eEF1A1/EF1A1) is required for genotoxic stress response and maintaining the malignancy of colorectal cancer (CRC) cells. The evolutionarily conserved site K439 is identified as the key acetylation site. Tissue expression analysis demonstrates that the acetylation level of eEF1A1 K439 is higher than paired normal tissues. Most importantly, hyperacetylation of eEF1A1 at K439 negatively correlates with CRC patient survival. Mechanistically, CBP and SIRT1 are the major acetyltransferase and deacetylase of eEF1A1. Hyperacetylation of eEF1A1 at K439 shows a significant tumor-promoting effect by increasing the capacity of proliferation, migration, and invasion of CRC cells. Our findings identify the altered post-translational modification at the translation machines as a critical factor in stress response and susceptibility to colorectal carcinogenesis. [ABSTRACT FROM AUTHOR]

Summary: SIRT1, a NAD+-dependent histone deacetylase, plays crucial roles in multiple biological processes including gene transcription, cellular metabolism, stress response, and tumorigenesis. Xeroderma pigmentosum group A (XPA) is a core nucleotide excision repair (NER) factor essential for NER process. Here we show that SIRT1 plays an important role in the regulation of NER pathway. Downregulation of SIRT1 significantly sensitizes cells to UV irradiation. SIRT1 interacts with XPA, and the interaction is enhanced after UV irradiation. XPA can be acetylated at lysines 63 and 67. SIRT1 deacetylates XPA both in vitro and in cells. Importantly, SIRT1-mediated deacetylation of XPA is required for optimal NER pathway since XPA-deficient cells complemented with XPA-K6367Q, which mimics hyperacetylated XPA, display significantly higher UV sensitivity compared with the XPA cells complemented with wild-type XPA. Furthermore, SIRT1-mediated XPA deacetylation enhances its interaction with RPA32. Our results demonstrate that SIRT1 regulates NER pathway through modulation of XPA acetylation status. [ABSTRACT FROM AUTHOR]