Nucleophagy contributes to genome stability though TOP2cc and nucleolar components degradation

ABSTRACTThe nuclear architecture of mammalian cells can be altered as a consequence of anomalous accumulation of nuclear proteins or genomic alterations. Most of the knowledge about nuclear dynamics comes from studies on cancerous cells. How normal, healthy cells maintain genome stability avoiding accumulation of nuclear damaged material is less understood. Here we describe that primary mouse embryonic fibroblasts develop a basal level of nuclear buds and micronuclei, which increase after Etoposide-induced DNA Double-Stranded Breaks. These nuclear buds and micronuclei co-localize with autophagic proteins BECN1 and LC3 and with acidic vesicles, suggesting their clearance by nucleophagy. Some of the nuclear alterations also contain autophagic proteins and Type II DNA Topoisomerases (TOP2A and TOP2B), or nucleolar protein Fibrillarin, implying they are also targets of nucleophagy. We propose that a basal nucleophagy contributes to genome and nuclear stability and also in response to DNA damage and nucleolar stress.

Evaluation of genotoxicity in buccal mucosa of patients subjected to X-rays by degenerative nuclear alterations study

The aim of this study is to explore the genotoxicity of cells obtained from the buccal mucosa in patients who were exposed to dental X-rays using micronucleus analysis. All the subjects underwent a routine oral clinical examination and subjects with any visible or symptomatic change in the buccal mucosa were excluded. Subjects who were expose to X rays in the past 6 months were also excluded. Based on the inclusion and exclusion criteria a total of 116 subjects were recruited. The included subjects were all nonsmokers. The genotoxicity was studied by micronucleus assay. There was significant difference in the frequency of multinucleated cell numbers from before exposure to after exposure to OPG. In patients having exposed to CBCT, a higher cell turnover was detected. The number of multinucleated cells gradually increases after panoramic radiographs, hence dental X-rays should be prescribed only when absolutely necessary.

Nuclear dynamics and stress responses in Alzheimer’s disease

In response to extracellular and intracellular stressors, the nucleus and nuclear compartments undergo distinct molecular changes to maintain cell homeostasis. In the context of Alzheimer’s disease, misfolded proteins and various cellular stressors lead to profound structural and molecular changes at the nucleus. This review summarizes recent research on nuclear alterations in AD development, from the nuclear envelope changes to chromatin and epigenetic regulation and then to common nuclear stress responses. Finally, we provide our thoughts on the importance of understanding cell-type-specific changes and identifying upstream causal events in AD pathogenesis and highlight novel sequencing and gene perturbation technologies to address those challenges.

ANALISIS SITOGENETIK SEL EPITEL MUKOSA BUKAL PEKERJA STASIUN PENGISI BAHAN BAKAR UMUM DI KOTA YOGYAKARTA

Workers employed in petroleum station have a high-risk exposure to a wide range of toxic compounds with known mutagenic and carcinogenic potential. Cytogenetic damage might have happened if they continuously exposed to petroleum derivatives. This study aimed to analyse the cytogenetic damage in exfoliated buccal cells among petroleum station workers in Yogyakarta City. This cross-sectional study was carried out on 30 petrol station workers who are working at a different petrol station in Yogyakarta and the control group consisted of 30 healthy subjects. Examination for all subjects included frequencies of nuclear abnormalities, including pycnosis, karyorrhexis, and karyolysis. Cytological preparations were stained according to papanicolaou reaction and analyzed under light microscope for making a score for degenerative nuclear alterations (pycnosis, karyolysis and karyorrhexis). Analysis of buccal cells revealed that frequencies of pycnosis and karyorrhexis in petrol station workers were significantly higher than the control group (P<0.05). Conversely, there was no significant difference in karyolisis among groups. These findings indicate that the petrol station workers are under the risk of significant cytogenetic damage, particularly pycnosis and karyorrhexis.

In Vitro Evaluation of Rigosertib Antitumoral and Radiosensitizing Effects against Human Cholangiocarcinoma Cells

Cholangiocarcinoma is the first most common cancer of the biliary tract. To date, surgical resection is the only potentially curative option, but it is possible only for a limited percentage of patients, and in any case survival rate is quite low. Moreover, cholangiocarcinoma is often chemotherapy-resistant, and the only drug with a significant benefit for patient’s survival is Gemcitabine. It is necessary to find new drugs or combination therapies to treat nonresectable cholangiocarcinoma and improve the overall survival rate of patients. In this work, we evaluate in vitro the antitumoral effects of Rigosertib, a multi-kinase inhibitor in clinical development, against cholangiocarcinoma EGI-1 cell lines. Rigosertib impairs EGI-1 cell viability in a dose- and time-dependent manner, reversibility is dose-dependent, and significant morphological and nuclear alterations occur. Moreover, Rigosertib induces the arrest of the cell cycle in the G2/M phase, increases autophagy, and inhibits proteasome, cell migration, and invasion. Lastly, Rigosertib shows to be a stronger radiosensitizer than Gemcitabine and 5-Fluorouracil. In conclusion, Rigosertib could be a potential therapeutic option, alone or in combination with radiations, for nonresectable patients with cholangiocarcinoma.

Genotoxicity evaluation of levonorgestrel-releasing intrauterine system (LNG-IUS) in exfoliated cervical cells using the micronucleus (MN) test

Purpose: This study aimed to determine whether any relationships exist between the levonorgestrel-releasing intrauterine system (LNG-IUS) and micronuclei or other nuclear anomalies, including condensed chromatin, karyorrhexis, and karyolysis, on the cervical epithelium in young women. Methods: A prospective observational study was conducted. The study population comprised healthy women aged ≤40 years who were referred for birth control. Cervical smears that were obtained from 18 women before and three months after LNG-IUS insertion were tested for micronuclei and other nuclear anomaliesusing the micronucleus test. Results: The results revealed no statistically significant difference (P>0.05) in the frequency of micronucleated exfoliated cervical mucosa cells after LNG-IUS exposure. However, LNG-IUS was able to increase other nuclear alterations closely related to cytotoxicity. Conclusions: Data indicated that exposure to LNG-IUS may not be a factor in inducing chromosomal damage, but it can promote cytotoxicity.

Noninvasive Encapsulated Papillary RAS-Like Thyroid Tumor (NEPRAS)

Introduction: The diagnosis of thyroid tumors arising from follicular cells that are encapsulated/well delimited and noninvasive is a challenge. When unequivocal nuclear alterations are present, the final diagnosis can range from noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) and classical/encapsulated papillary thyroid cancer (PTC), including aggressive subtypes, to poorly differentiated carcinoma. As proposed recently, the presence of papillae in the absence of exuberant nuclear alterations (nuclear score 2), given that the other criteria for NIFTP are met, may not be sufficient for the diagnosis of PTC. This condition is called “noninvasive encapsulated papillary RAS-like thyroid tumor” (NEPRAS), whose nature would be borderline and not malignant. Revising our cases of tumors &gt; 1 cm that were diagnosed previously as PTC and that were encapsulated/well delimited and noninvasive, we found three cases of NEPRAS. We now revised our cases of tumors &gt; 1 cm diagnosed previously as well-differentiated tumor of uncertain malignant potential (WDT-UMP) because the nuclear alterations were not considered to be sufficient for the diagnosis of PTC on that occasion. Case: In a 29-year-old euthyroid male patient with a single thyroid nodule whose fine-needle aspiration had revealed indeterminate cytology, a single tumor measuring 3.2 cm was reclassified from WDT-UMP to NEPRAS. For this diagnosis, the tumor met the following criteria: encapsulation or clear demarcation, no vascular or capsular invasion, presence of papillae, &lt; 30% solid/trabecular/insular growth pattern, no tumor necrosis or high mitotic activity, and nuclear score 2. The BRAFV600E mutation was absent. The patient continues to show no signs of recurrence 7 years after lobectomy. Conclusion: Despite the presence of papillae, some tumors may be reclassified from malignant (encapsulated PTC) to borderline (NEPRAS). This proposal would result in a change of management, with the same implications as those seen for the change from noninvasive encapsulated follicular variant of PTC to NIFTP. References: Ohba K et al. Encapsulated Papillary Thyroid Tumor with Delicate Nuclear Changes and a KRAS Mutation as a Possible Novel Subtype of Borderline Tumor. J Pathol Transl Med. 2019;53:136-41 AND Rosario PW. Noninvasive encapsulated papillary RAS-like thyroid tumor (NEPRAS) or encapsulated papillary thyroid carcinoma (PTC). J Pathol Transl Med. 2020;54:263-4.

In vitro Elucidation of Antiproliferative and Apoptotic Effects of Thymol against Prostate Cancer LNCaP Cells

Recent research suggested the role of plant-derived bioactive compounds as potent anticancer agents. Thymol, a monoterpene phenol, possesses numerous pharmacological properties such as antioxidant, anti-inflammatory, and antitumor effects. However, the inhibitory potential of thymol on prostate cancer cells still elusive. Therefore, the purpose of this study is to explore the antiproliferative and apoptotic effects of thymol against prostate cancer LNCaP cells. Our results indicated dose-dependent growth inhibitory effects of thymol on prostate cancer LNCaP cells. Morphological analysis and DAPI staining revealed that thymol induces marked morphological and nuclear alterations in LNCaP cells. Moreover, thymol could induce significant apoptosis in LNCaP cells through caspase-3 activation and modulation of mRNA expression of apoptotic-related genes. Overall, these findings showed that thymol could offer a novel therapeutic approach against prostate cancer.

Nuclear Reorganization in Hippocampal Granule Cell Neurons from a Mouse Model of Down Syndrome: Changes in Chromatin Configuration, Nucleoli and Cajal Bodies

Down syndrome (DS) or trisomy of chromosome 21 (Hsa21) is characterized by impaired hippocampal-dependent learning and memory. These alterations are due to defective neurogenesis and to neuromorphological and functional anomalies of numerous neuronal populations, including hippocampal granular cells (GCs). It has been proposed that the additional gene dose in trisomic cells induces modifications in nuclear compartments and on the chromatin landscape, which could contribute to some DS phenotypes. The Ts65Dn (TS) mouse model of DS carries a triplication of 92 genes orthologous to those found in Hsa21, and shares many phenotypes with DS individuals, including cognitive and neuromorphological alterations. Considering its essential role in hippocampal memory formation, we investigated whether the triplication of this set of Hsa21 orthologous genes in TS mice modifies the nuclear architecture of their GCs. Our results show that the TS mouse presents alterations in the nuclear architecture of its GCs, affecting nuclear compartments involved in transcription and pre-rRNA and pre-mRNA processing. In particular, the GCs of the TS mouse show alterations in the nucleolar fusion pattern and the molecular assembly of Cajal bodies (CBs). Furthermore, hippocampal GCs of TS mice present an epigenetic dysregulation of chromatin that results in an increased heterochromatinization and reduced global transcriptional activity. These nuclear alterations could play an important role in the neuromorphological and/or functional alterations of the hippocampal GCs implicated in the cognitive dysfunction characteristic of TS mice.

RAC1 induces nuclear alterations through the LINC complex to enhance melanoma invasiveness

In our manuscript we show that GTPases RAC, RHO, and CDC42 were able to modify the nuclear morphology, especially Rac1 protein. Rac1 induces nuclear morphology alterations to enhance invasion of melanoma cells.