Construction of a plasmid for overexpression of human circadian gene period2 and its biological activity in osteosarcoma cells

Molecular mechanism of thiram-induced abnormal chondrocyte proliferation via lncRNA MSTRG.74.1-BNIP3 axis

Thiram, a widely used organic pesticide in agriculture, exhibits both bactericidal and insecticidal effects. However, prolonged exposure to thiram has been linked to bone deformities and cartilage damage, contributing to the development of tibial dyschondroplasia (TD) in broilers and posing a significant threat to global agricultural production. TD, a prevalent nutritional metabolic disease, manifests as clinical symptoms like unstable standing, claudication, and sluggish movement in affected broilers. In recent years, there has been growing recognition of the regulatory role of long non-coding RNA (lncRNA) in tibial cartilage formation among broilers through diverse signaling pathways. This study employs in vitro experimental models, growth performance analysis, and clinical observation to assess broilers' susceptibility to thiram pollution. Transcriptome sequencing analysis revealed a significant elevation in the expression of lncRNA MSTRG.74.1 in both the con group and the thiram-induced in vitro group. The results showed that lncRNA MSTRG.74.1 plays a pivotal role in influencing the proliferation and abnormal differentiation of chondrocytes. This regulation occurs through the negative modulation of apoptotic genes, including Bax, Cytc, Bcl2, Apaf1, and Caspase3, along with genes Atg5, Beclin1, LC3b, and protein p62. Moreover, the overexpression of lncRNA MSTRG.74.1 was found to regulate broiler chondrocyte development by upregulating BNIP3. In summary, this research sheds light on thiram-induced abnormal chondrocyte proliferation in TD broilers, emphasizing the significant regulatory role of the lncRNA MSTRG.74.1-BNIP3 axis, which will contribute to our understanding of the molecular mechanisms underlying TD development in broilers exposed to thiram.

Impact of chrono-radiotherapy on the prognosis and treatment-related toxicity in patients with locally advanced nasopharyngeal carcinoma: A multicenter propensity-matched study

The timing of radiotherapy (RT) delivery has been reported to affect both cancer survival and treatment toxicity. However, the association among the timing of RT delivery, survival, and toxicity in locally advanced nasopharyngeal carcinoma (LA-NPC) has not been investigated. We retrospectively reviewed patients diagnosed with LA-NPC who received definitive RT at multiple institutions. The median RT delivery daytime was categorized as morning (DAY) and night (NIGHT). Seasonal variations were classified into the darker half of the year (WINTER) and brighter half (SUMMER) according to the sunshine duration. Cohorts were balanced according to baseline characteristics using propensity score matching (PSM). Survival and toxicity outcomes were evaluated using Cox regression models. A total of 355 patients were included, with 194/161 in DAY/NIGHT and 187/168 in WINTER/SUMMER groups. RT delivered during the daytime prolonged the 5-year overall survival (OS) (90.6% vs. 80.0%, p = 0.009). However, the significance of the trend was lost after PSM (p = 0.068). After PSM analysis, the DAY cohort derived a greater benefit in 5-year progression-free survival (PFS) (85.6% vs. 73.4%, p = 0.021) and distant metastasis-free survival (DMFS) (89.2% vs. 80.8%, p = 0.051) in comparison with the NIGHT subgroup. Moreover, multivariate analysis showed that daytime RT was an independent prognostic factor for OS, PFS, and DMFS. Furthermore, daytime RT delivery was associated with an increase in the incidence of leukopenia and radiation dermatitis. RT delivery in SUMMER influenced only the OS significantly (before PSM: p = 0.051; after PSM: p = 0.034). There was no association between toxicity and the timing of RT delivery by season. In LA-NPC, the daytime of radical RT served as an independent prognostic factor. Furthermore, RT administered in the morning resulted in more severe toxic side effects than that at night, which needs to be confirmed in a future study.

Hypoxic Conditions Modulate Chondrogenesis through the Circadian Clock: The Role of Hypoxia-Inducible Factor-1α

Hypoxia-inducible factor-1 (HIF-1) is a heterodimer transcription factor composed of an alpha and a beta subunit. HIF-1α is a master regulator of cellular response to hypoxia by activating the transcription of genes that facilitate metabolic adaptation to hypoxia. Since chondrocytes in mature articular cartilage reside in a hypoxic environment, HIF-1α plays an important role in chondrogenesis and in the physiological lifecycle of articular cartilage. Accumulating evidence suggests interactions between the HIF pathways and the circadian clock. The circadian clock is an emerging regulator in both developing and mature chondrocytes. However, how circadian rhythm is established during the early steps of cartilage formation and through what signaling pathways it promotes the healthy chondrocyte phenotype is still not entirely known. This narrative review aims to deliver a concise analysis of the existing understanding of the dynamic interplay between HIF-1α and the molecular clock in chondrocytes, in states of both health and disease, while also incorporating creative interpretations. We explore diverse hypotheses regarding the intricate interactions among these pathways and propose relevant therapeutic strategies for cartilage disorders such as osteoarthritis.

Period 2 Suppresses the Malignant Cellular Behaviors of Colorectal Cancer Through the Epithelial-Mesenchymal Transformation Process

Introduction

The PER2 (Period circadian regulator 2) gene is related to the circadian clock, and it has been deemed as a suppressor gene in osteosarcoma and lung carcinoma. However, the part of PER2 in CRC (colorectal cancer) needs to be further determined.

Methods

First, we collected clinical samples to detect PER2 expression in CRC. Then, we used cell transfection to knock down PER2 expression in CRC cell lines and performed a series of functional experiments to elucidate the effects of PER2 on CRC cells. We next verified whether PER2 affects the epithelial-mesenchymal transformation (EMT) process in CRC by conducting quantitative real-time PCR and western blotting.

Results

In the research, we revealed that the expression of PER2 decreased in CRC clinical samples. In addition, knocking down PER2 expression caused CRC cells to acquire malignant biological features. Finally, we found that PER2 knockdown may activate the Snail/Slug axis through inhibiting p53, therefore promote the activation of the EMT pathway.

Conclusion

In conclusion, low PER2 expression reinforces migration and activates EMT in CRC, suggesting that PER2 is closely related to CRC development and could be used as a potential treatment site in the clinic.

Circadian Gene PER2 Silencing Downregulates PPARG and SREBF1 and Suppresses Lipid Synthesis in Bovine Mammary Epithelial Cells

Simple Summary

The present study was constructed to determine the effects of the core circadian clock gene, Period 2 (PER2), on lipid synthesis in bovine mammary epithelial cells (BMECs). Data revealed that PER2-regulated genes were involved in fatty acid de novo synthesis, desaturation, TAG accumulation, and lipid droplet secretion in primary BMECs, partly by inhibiting PPARG and SREBF1. Our overall data suggests that PER2 in bovine mammary cells plays a role in regulating milk fat synthesis directly, or via the activation of the transcription regulators PPARG and SREBF1. This study provides molecular evidence underscoring a link between the circadian clock and lipid metabolism in bovines.

Abstract

PER2, a circadian clock gene, is associated with mammary gland development and lipid synthesis in rodents, partly via regulating peroxisome proliferator-activated receptor gamma (PPARG). Whether such a type of molecular link existed in bovines was unclear. We hypothesized that PER2 was associated with lipid metabolism and regulated cell cycles and apoptosis in bovine mammary epithelial cells (BMECs). To test this hypothesis, BMECs isolated from three mid-lactation (average 110 d postpartum) cows were used. The transient transfection of small interfering RNA (siRNA) was used to inhibit PER2 transcription in primary BMECs. The silencing of PER2 led to lower concentrations of cellular lipid droplets and triacylglycerol along with the downregulation of lipogenic-related genes such as ACACA, FASN, LPIN1, and SCD, suggesting an overall inhibition of lipogenesis and desaturation. The downregulation of PPARG and SREBF1 in response to PER2 silencing underscored the importance of circadian clock signaling and the transcriptional regulation of lipogenesis. Although the proliferation of BMECs was not influenced by PER2 silencing, the number of cells in the G2/GM phase was upregulated. PER2 silencing did not affect cell apoptosis. Overall, the data provided evidence that PER2 participated in the coordination of mammary lipid metabolism and was potentially a component of the control of lipid droplets and TAG synthesis in ruminant mammary cells. The present data suggested that such an effect could occur through direct effects on transcriptional regulators.

The circadian clock gene PER2 enhances chemotherapeutic efficacy in nasopharyngeal carcinoma when combined with a targeted nanosystem

Treatment failure occurs in more than 40% of advanced nasopharyngeal carcinoma (NPC) patients including local recurrence and distant metastasis due to chemoradioresistance. Circadian clock genes were identified as regulating cancer progression and chemoradiosensitivity in a time-dependent manner. A novel nanosystem can ensure the accumulation and controllable release of chemotherapeutic agents at the tumour site at a set time. In this study, we investigated the expression of circadian clock genes and identified that period circadian regulator 2 (PER2) as a tumour suppressor plays a key role in NPC progression. A label-free proteomic approach showed that PER2 overexpression can inhibit the ERK/MAPK pathway. The chemotherapeutic effect of PER2 overexpression was assessed in NPC together with the nanosystem comprising folic acid (FA), upconverting nanoparticles covalently coupled with Rose Bengal (UCNPs-RB), 10-hydroxycamptothecin (HCPT) and lipid-perfluorohexane (PFH) (FURH-PFH-NPs). PER2 overexpression combined with the targeted and controlled release of nanoagents elevated chemotherapeutic efficacy in NPC, which has potential application value for the chronotherapy of tumours.

The circadian rhythm and core gene Period2 regulate the chemotherapy effect and multidrug resistance of ovarian cancer through the PI3K signaling pathway

Background: Ovarian cancer is the most lethal cancer in the female reproductive system. It has been shown that ‘time chemotherapy’ of ovarian cancer has an important impact on the chemotherapy effect and prognosis of patients, but the specific mechanism is not known. Methods: We designed a case–control study in strict accordance with epidemiological principles. We collected resection samples of ovarian cancer patients who worked night-shifts and those who did not, and analyzed the differences in protein expression. Through construction of a normal/circadian-rhythm disorder model of ovarian cancer in nude mice, we explored the molecular mechanism of a ‘biological clock’ rhythm on treatment of ovarian cancer. Results: Expression of interleukin (IL)-6, programmed cell death receptor-1 (PD-1) and programmed death ligand 1 (PD-L1) increased, and expression of tumor necrosis factor (TNF)-α, Period 1 (Per1) and Period 2 (Per2) decreased in the night-shift group. Methylation of CpG islands in the promoter of Per2 could result in its decreased expression in SKOV3/DDP (Cisplatin) cells. Dysrhythmia of the circadian clock: (i) had a negative effect on the chemotherapy effect against ovarian cancer; (ii) affected expression of immune factors and the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signaling pathway. Conclusion: The Per2 gene can affect the drug resistance of ovarian cancer by inhibiting the PI3K/Akt signaling pathway and then acting on its downstream drug-resistance factors, thereby providing a new target for ovarian cancer treatment.

Time to fight: targeting the circadian clock molecular machinery in cancer therapy

The circadian clock regulates a wide range of molecular pathways and biological processes. The expression of clock genes is often altered in cancer, fostering tumor initiation and progression. Inhibition and activation of core circadian clock genes, as well as treatments that restore circadian rhythmicity, have been successful in counteracting tumor growth in different experimental models. Here, we provide an up-to-date overview of studies that show the therapeutic effects of targeting the clock molecular machinery in cancer, both genetically and pharmacologically. We also highlight future areas for progress that offer a promising path towards innovative anticancer strategies. Substantial limitations in the current understanding of the complex interplay between the circadian clock and cancer in vivo need to be addressed in order to allow clock-targeting therapies in cancer.

Circadian Clock Protein PERIOD2 Suppresses the PI3K/Akt Pathway and Promotes Cisplatin Sensitivity in Ovarian Cancer

Background

The mortality rate of ovarian cancer is the highest among gynecological tumors. The two factors leading to high mortality of ovarian cancer are late clinical stage and chemotherapy resistance. It is very important to reverse or intervene chemotherapy resistance. Abnormal circadian rhythm is related to the occurrence of tumor, and circadian clock protein PERIOD2 (PER2) acts as a tumor suppressor in cancer; however, little is known about its involvement in chemosensitivity.

Methods

This study aimed to investigate the role and underlying mechanisms of PER2 in ovarian cancer sensitivity to cisplatin. Overexpression and knockdown of PER2 were performed to explore its role in ovarian cancer cell sensitivity to cisplatin both in vitro and in vivo. The protein levels of PI3K, AKT, caspase 3, E-cadherin, and other drug resistance-related molecules were determined in parental SKOV3 and SKOV3/DDP cells as well as in xenograft tumor tissues.

Results

Compared with parental cells, SKOV3/DDP cells had dramatically decreased PER2 expression, possibly due to hypermethylation in the PER2 promoter. PER2 overexpression significantly inhibited proliferation while promoting cisplatin-induced apoptosis in SKOV3 and SKOV3/DDP cells. In agreement, PER2-overexpressing SKOV3/DPP cells yielded significantly reduced tumor mass in cisplatin-treated mice compared with control cells. Mechanistically, PER2 overexpression remarkably reduced the protein amounts of PI3K, AKT, and MDR1 while increasing those of caspase 3 and E-cadherin in tumor tissues. Knockdown of PER2 exhibited opposite effects. PER2 overexpression also reduced the serum levels of TNF-α and IL-6 in tumor-bearing mice before the initiation of cisplatin treatment.

Conclusion

This study suggests that loss of PER2 contributes to cisplatin resistance in SKOV3 cells, possibly by activating the PI3K/AKT pathway and EMT, inhibiting apoptosis, and promoting drug efflux and inflammatory responses. Overexpression of PER2 could reverse these alterations and sensitize both parental SKOV3 and SKOV3/DDP cells to cisplatin.

Research on circadian clock genes in common abdominal malignant tumors

Circadian rhythm describes the 24-h oscillation in physiology and behavior of living organisms and presents a timing controller for life activity. Studies in recent years have reported that the abnormal expression of clock genes is closely related to the development of common abdominal malignant tumors. The expression of the 14 kinds of clock genes in 6 abdominal malignant tumors from Cancer Genome Atlas (TCGA) data was integrated and analyzed using R and Perl programming languages to show the association between clock gene expression and prognosis of cancer patients. Analysis of TCGA data indicated that the overexpression of Per1-3, Cry2, CLOCK, NR1D2 and RORA with underexpression of Timeless and NPAS2 was associated with a favorable prognosis in kidney cancer. In liver cancer, high expressions of Cry2 and RORA were correlated with prolonged overall survival (OS) in patients, while high expressions of NPAS2 and Timeless were correlated with a poor survival. High expression of CLOCK was positively correlated with OS in colon cancer patients. High expression of Cry2 and low expression of DEC1 were associated with a favorable prognosis in pancreatic cancer patients, respectively. Most of these clock-genes expressions were closely related to the clinical stage and degree of tumor differentiation of patients. Aberrant clock gene expression is related to the biological characteristics of abdominal malignant tumors, which likely has a causal role in cancer development and survival.

Velvet Antler compounds targeting major cell signaling pathways in osteosarcoma - a new insight into mediating the process of invasion and metastasis in OS

Velvet antler is the only renewable bone tissue of mammalian animals, which consists of a variety of growth factors, amino acids and polypeptides. But the mechanism of high-speed proliferation without carcinogenesis is still mystifying. The previous study of this work found that the velvet antler peptides (VAP) could not only inhibit the proliferation and migration of osteosarcoma cell lines MG-63 and U2OS, but also induced U2OS apoptosis and inhibited MG-63 epithelial-mesenchymal transition (EMT) through TGF-β and Notch pathways. These results lead us to conclude that VAP has the potential ability to mediate osteosarcoma cells by regulating related signaling pathways and growth factors. Therefore, finding a new appropriate inhibitor for OS is a valuable research direction, which will give patients a better chance to receive proper therapy. From an applied perspective, this review summarized the effects of velvet antler, genes, growth factors and research progress of relative pathways and genes of osteosarcoma, which are poised to help link regenerative molecular biology and regenerative medicine in osteosarcoma pathogenesis.

Current Status of Research on the Period Family of Clock Genes in the Occurrence and Development of Cancer

Several physiological activities of organisms are coordinated based on periodic variations of ~24 h, which is called a circadian rhythm. Circadian rhythms, driven by circadian clock genes, play an important role in the regulation of various complex life activities of organisms, in an orderly and coordinated manner. Period (Per)1/2/3 genes are important core clock genes and part of the Per gene family. Current research has demonstrated that the abnormal expression of Per genes and disruption of circadian rhythms can lead to the occurrence and development of cancer; however, the exact mechanism has not yet been elucidated. Further study on this mechanism may lead to the discovery of new, effective therapies for the prevention and treatment of cancer. The present review summarizes the status of current research with regards to the association between the abnormal expression and rhythmic variation of the Per gene family, and carcinogenesis and progression of cancer.

Loss of the clock gene PER2 is associated with cancer development and altered expression of important tumor-related genes in oral cancer

Recent studies have demonstrated that abnormal expression of the clock gene PER2 is closely associated with the development of a variety of cancer types. However, the expression of PER2 in oral squamous cell carcinoma (OSCC), a common malignant tumor in humans, and its correlations with the clinicopathological parameters and survival time of OSCC patients and the altered expression of important tumor-related genes remain unclear. In the present study, we detected the mRNA and protein expression levels of PER2, PIK3CA, PTEN, P53, P14ARF and caspase‑8 in OSCC tissues and cancer-adjacent oral mucosa by reverse transcription-quantitative PCR (RT-qPCR), western blotting and immunohistochemistry. The results showed that the PER2, PTEN, P53, P14ARF and caspase‑8 mRNA and protein expression levels in OSCC were significantly reduced compared with those in cancer-adjacent tissues. Additionally, the PIK3CA protein expression level was significantly increased in OSCC tissues, whereas the mRNA level was not. Decreased expression of PER2 was significantly associated with advanced clinical stage and the presence of lymphatic metastasis in OSCC patients. Patients with PER2‑negative expression had a significantly shorter survival time than those with PER2‑positive expression. PER2 expression was negatively correlated with PIK3CA and P53 levels, and positively correlated with PTEN, P14ARF and caspase‑8 levels. In summary, the results of this study suggest that loss of PER2 expression is closely associated with the genesis and development of OSCC and that PER2 may be an important prognostic biomarker in OSCC. PER2 may serve an antitumor role via the P53/P14ARF, PIK3CA/AKT and caspase‑8 pathways.

The circadian clock gene PER2 plays an important role in tumor suppression through regulating tumor-associated genes in human oral squamous cell carcinoma

Low expression of the clock gene PER2 is closely related to carcinogenesis and the development of cancer; however, the mechanism of the low expression of PER2 that led to cell malignant transformation remains unclear. This study used RNA interference (RNAi) technology to silence PER2 in SCC15 human oral squamous cell carcinoma (OSCC) cells. Then it was found that the ability of cancer cell proliferation, migration, and invasion were markedly increased (P<0.05), and the ability of cancer cell apoptosis and the number of cells in G1/G0 phase were markedly reduced (P<0.05) after PER2 knockdown. PER2 knockdown increased the expression of Ki-67, MDM2, c-Myc, Bcl-2, MMP2, and VEGF mRNA (P<0.05), and decreased the expression of p53, Bax, and TIMP-2 mRNA (P<0.05). The in vivo experiments also proved that the tumorigenicity of SCC15 cells was significantly enhanced after PER2 silence (P<0.05). Overall, these results show that PER2 through the regulation of the numerous important downstream tumor-related genes, plays a major role in tumor suppression, and it may be a novel molecular target for cancer treatment.