Centromere defects in Systemic Sclerosis (SSc) have remained unexplored despite the fact that many centromere proteins were discovered in patients with SSc. Here we report that lesion skin fibroblasts from SSc patients show marked alterations in centromeric DNA. SSc fibroblasts also show DNA damage, abnormal chromosome segregation, aneuploidy (only in diffuse cutaneous (dcSSc)) and micronuclei (in all types of SSc), some of which lose centromere identity while retaining centromere DNA sequences. Strikingly, we find cytoplasmic “leaking” of centromere proteins in limited cutaneous SSc (lcSSc) fibroblasts. Cytoplasmic centromere proteins co-localize with antigen presenting MHC Class II molecules, which correlate precisely with the presence of anti-centromere antibodies. CENPA expression and micronuclei formation correlate highly with activation of the cGAS-STING/IFN-β pathway as well as markers of reactive oxygen species (ROS) and fibrosis, ultimately suggesting a link between centromere alterations, chromosome instability, SSc autoimmunity, and fibrosis.

The aim of the present study was to decipher the mechanism of glutathione‑S‑transferase Ω‑1 (GSTO1)‑induced drug resistance in colon cancer cells. Cisplatin is used widely as a therapeutic drug in cancer, but colon cancer is the most susceptible to acquired drug resistance. Autophagy is recognized as one of the contributors to drug resistance in cancers. Phase II detoxifying enzymes, such as GSTO1, serve important roles in autophagy‑apoptosis cross talk. The present study revealed a novel interaction between GSTO1 and TNFα‑induced protein 3/zinc‑finger protein A20 (TNFαIP3/A20) as a prime target for cisplatin sensitization in drug‑resistant cells. GSTO1 and ATP‑binding cassette subfamily B member 1 (ABCB1) were both expressed at higher levels in multidrug‑resistant (MDR) HCT‑116 cells compared with the wild‑type (WT) HCT‑116 cells, suggesting they may serve vital roles in multidrug resistance. MDR cells showed autophagy induction, which is dependent on calcium signaling‑dependent endoplasmic stress. In WT cells, the mitochondria‑dependent pathway leads to apoptosis, which was not observed in MDR cells. The MDR conditions were mimicked by transfecting WT cells with the GSTO1‑activation CRISPR plasmid, which induced autophagy. Similarly, MDR cells with GSTO1‑knockdown (KD) CRISPR/Cas9 transfection showed reduced autophagy with increased apoptosis. These data revealed a potentially important role of GSTO1 in drug resistance. A GSTO1 pull‑down assay detected TNFαIP3/A20 as a binding partner in MDR cells. The data suggested that the expression of TNFαIP3/A20 may be dependent on GSTO1 expression in MDR cells. Targeting either GSTO1 or TNFαIP3/A20 by CRISPR/Cas9 sensitized the MDR cells to cisplatin. GSTO1 and TNFαIP3/A20 dual‑KD cells were more sensitive to cisplatin compared with single‑gene KD cells. These data highlight the importance of the GSTO1‑TNFαIP3/A20 interaction during drug resistance.

Autophagy and apoptosis are two evolutionarily conserved catabolic processes that play important roles in maintaining cellular homeostasis and in determining cell fate when cells are exposed to various stresses in vivo. The interaction between autophagy and apoptosis has been studied extensively in cancer research, and it has been shown to affect cancer initiation and tumor formation, disease progression, therapeutic resistance, and overall survival. Autophagy typically functions as a cytoprotective mechanism in cancer cells subjected to metabolic, hypoxic, or therapeutic stress, whereas apoptosis primarily functions as an intrinsic programmed cell death pathway. While apoptosis and autophagy function as distinct pathways, there is significant molecular crosstalk, allowing cells to modulate their behavior from survival to death depending on the severity and duration of exposure to a given stressor and the cellular environment. This review examines the molecular landscape of the autophagy–apoptosis interplay in cancers, with special attention paid to the major signaling pathways involved and their biological outcomes in oncology. We examine the molecular mechanisms and signal transduction pathways involved in the crosstalk between autophagy and apoptosis in cancer. In particular, we focus on several key proteins that regulate this crosstalk, including kinases, caspases, heat shock proteins and transcription factors. Furthermore, we describe the major signal transduction pathways that regulate this crosstalk, including the PI3K/Akt/mTOR, MAPK, unfolded protein response, oxidative stress, and calcium signaling pathways. Additionally, we discussed how dysregulation of these pathways contributes to cancer progression and treatment resistance. Finally, we summarized the use of currently available therapeutic agents targeting the crosstalk between autophagy and apoptosis, including FDA-approved drugs and natural products, with the potential to enhance the effectiveness of anticancer treatments. A better understanding of this complex process will allow the development of new, precision-based, combination cancer therapies.

Fibrosis in systemic sclerosis (SSc or scleroderma) is characterized by an abundance of chromosome segregation defects and chromosome instability (CIN) that lead to overactivation of autoimmunity and inflammation. This chapter will emphasize the most recent findings on the involvement of centromere and telomere dysfunction in scleroderma. We will discuss how centromere and telomere dysfunction contribute to CIN, fibrosis, and cellular autoimmunity in scleroderma. We will also summarize how chromosome segregation defects in the form of aneuploidy and micronuclei formation activate the Cyclic GMPAMP synthase (cGAS) Stimulator of interferon genes (STING) pathway of cellular immunity. Activation of this pathway induces production of inflammatory cytokines IFN and IL6. Finally, we will summarize the most recent therapies to block the cGAS-STING pathway and treat fibrosis.

Telomeres protect chromosome ends and determine the proliferative potential of cells. The canonical telomere sequence TTAGGG is synthesized by telomerase holoenzyme, which maintains telomere length in proliferative stem cells. Although the core components of telomerase are well defined, many aspects of telomerase regulation are poorly understood. We report a novel role for the Src family kinase Fyn, which interrupts telomere maintenance in stem cells by negatively regulating telomerase assembly. We determine that Fyn promotes SUMOylation of the scaffold protein menin at lysine 609 (K609) by phosphorylating menin at tyrosine 603 (Y603). We show that K609-SUMOylated menin associates with much greater affinity to the telomerase RNA component (TERC) and interferes with telomerase assembly by preventing dyskerin (DKC1) and H/ACA ribonucleoprotein complex subunit 1 (GAR1) from binding to TERC. Importantly, we find that inhibition of Fyn reduces telomere shortening in human iPSCs and mice harboring mutations for dyskeratosis congenita.

Telomeres protect chromosome ends and determine the replication potential of dividing cells. The canonical telomere sequence TTAGGG is synthesized by telomerase holoenzyme, which maintains telomere length in proliferative stem cells. Although the core components of telomerase are well-defined, mechanisms of telomerase regulation are still under investigation. We report a novel role for the Src family kinase Fyn, which disrupts telomere maintenance in stem cells by phosphorylating the scaffold protein Menin. We found that Fyn knockdown prevented telomere erosion in human and mouse stem cells, validating the results with four telomere measurement techniques. We show that Fyn phosphorylates Menin at tyrosine 603 (Y603), which increases Menin’s SUMO1 modification, C-terminal stability, and importantly, its association with the telomerase RNA component (TR). Using mass spectrometry, immunoprecipitation, and immunofluorescence experiments we found that SUMO1-Menin decreases TR’s association with telomerase subunit Dyskerin, suggesting that Fyn’s phosphorylation of Menin induces telomerase subunit mislocalization and may compromise telomerase function at telomeres. Importantly, we find that Fyn inhibition reduces accelerated telomere shortening in human iPSCs harboring mutations for dyskeratosis congenita.