Expression of p27 and p16 and their clinical significance in gastric cancer

CDK regulators—Cell cycle progression or apoptosis—Scenarios in normal cells and cancerous cells

Serine/threonine kinases called cyclin-dependent kinases (CDKs) interact with cyclins and CDK inhibitors (CKIs) to control the catalytic activity. CDKs are essential controllers of RNA transcription and cell cycle advancement. The ubiquitous overactivity of the cell cycle CDKs is caused by a number of genetic and epigenetic processes in human cancer, and their suppression can result in both cell cycle arrest and apoptosis. This review focused on CDKs, describing their kinase activity, their role in phosphorylation inhibition, and CDK inhibitory proteins (CIP/KIP, INK 4, RPIC). We next compared the role of different CDKs, mainly p21, p27, p57, p16, p15, p18, and p19, in the cell cycle and apoptosis in cancer cells with respect to normal cells. The current work also draws attention to the use of CDKIs as therapeutics, overcoming the pharmacokinetic barriers of pan-CDK inhibitors, analyze new chemical classes that are effective at attacking the CDKs that control the cell cycle (cdk4/6 or cdk2). It also discusses CDKI's drawbacks and its combination therapy against cancer patients. These findings collectively demonstrate the complexity of cancer cell cycles and the need for targeted therapeutic intervention. In order to slow the progression of the disease or enhance clinical outcomes, new medicines may be discovered by researching the relationship between cell death and cell proliferation.

Nrf2 affects hydroquinone-induces cell cycle arrest through the p16/pRb signaling pathway and antioxidant enzymes

Hydroquinone (HQ), a well-known carcinogenic agent, induces oxidative stress, cell cycle arrest, apoptosis, and malignant transformation. As an antioxidant actor, the nuclear factor erythroid 2-related factor 2 (Nrf2) drives adaptive cellular protection in response to oxidative stress. The human lymphoblastoid cell line (TK6 cells) is widely used as a model for leukemia researches. In the present study, we focused on exploring whether Nrf2 regulatory cell cycle in TK6 cells upon HQ treatment and the underlying mechanisms. The results showed that the cell cycle arrest in TK6 cells induced by hydroquinone was accompanied by activation of the Nrf2 signaling pathway. We further clarified that Nrf2 loss accelerated cell cycle progression from G0/G1 to S and G2/M phases and promoted ROS production by downregulating the expression of SOD and GSH. Western blotting analysis indicated that Nrf2 regulated cell cycle progression via p16/pRb signaling pathways. Therefore, we conclude that Nrf2 is engaged in HQ-induced cell cycle arrest as well through p16/pRb and antioxidant enzymes.

Role of Genetic Variations in CDK2, CCNE1 and p27KIP1 in Prostate Cancer

BACKGROUND/AIM

Our aim was to investigate possible influences of genetic variants in genes involved in the G₁/S transition [cyclin-dependent kinase-2 (CDK2), cyclin E1 (CCNE1) and cyclin-dependent kinase inhibitor 1B (p27^KIP1)] on the expression/activity of their corresponding proteins and to assess the functional impact of these variants on the risk of prostate cancer.

MATERIALS AND METHODS

We genotyped 530 cases and 562 healthy controls for two relevant single nucleotide polymorphisms (CDK2 rs2069408 and CCNE1 rs997669) by TaqMan genotyping assay. p27^KIP1 rs2066827 polymorphisms were studied by polymerase chain reaction-restriction fragment length polymorphism assay. In addition, the expression of CDK2, CCNE1 and p27^KIP1 was evaluated by quantitative real-time-polymerase chain reaction and western blotting in 44 prostate cancer tissues and 31 benign prostatic hyperplasia tissues.

RESULTS

No association was found between CDK2 rs2069408, CCNE1 rs997669 or p27^KIP1 rs2066827 polymorphisms and an increased risk of prostate cancer development. Higher CDK2 expression was more prevalent in those with rs2069408 GG genotype than in AA carriers (p>0.05). We also noted reduced p27^KIP1 protein expression in those with the p27^KIP1 G109 allele. No difference was observed for CCNE1 expression in relation to the risky genotype (CC). A significant association was detected between CCNE1 mRNA overexpression and development of higher-grade carcinomas (Gleason score >7, p<0.05).

CONCLUSION

Polymorphisms CDK2 rs2069408, CCNE1 rs997669 and p27^KIP1 rs2066827 have no significant impact on prostate cancer risk nor on the gene and protein expression of CDK2, CCNE1 and p27^KIP1, although high CCNE1 expression was significantly associated with a higher tumour grade in patients with prostate cancer.

Knockdown of SNORA47 Inhibits the Tumorigenesis of NSCLC via Mediation of PI3K/Akt Signaling Pathway

Background

Non-small cell lung cancer (NSCLC) is a frequently diagnosed aggressive cancer all over the world. Small nucleolar RNAs (snoRNAs) are a group of non-coding mediatory RNAs. A previous report indicated that small nucleolar RNA 47 (SNORA47) is upregulated in NSCLC. However, the role of SNORA47 in NSCLC is unclear.

Material and Methods

Cell proliferation was measured by immunofluorescence staining. Cell apoptosis and cycle of NSCLC were tested by flow cytometry and the protein expressions were investigated by Western-blot. Meanwhile, cell migration and invasion were detected by transwell assay. Xenograft mice model was established to detect the effect of SNORA47 knockdown on tumor growth of NSLC in vivo.

Results

Knockdown of SNORA47 significantly inhibited the proliferation of NSCLC cells via inducing cell apoptosis. Moreover, migration and invasion of NSCLC cells were notably decreased by SNORA47 shRNA. SNORA47 knockdown significantly induced G1 arrest in NSCLC cells via regulation of p27 Kip1, CDK2, and cyclin D1. Meanwhile, SNORA47 shRNA inhibited EMT process and PI3K/Akt signaling in NSCLC cells. Finally, silencing of SNORA47 significantly inhibited the tumor growth of NSCLC in vivo.

Conclusion

Knockdown of SNORA47 significantly inhibited the tumorigenesis of NSCLC via inhibition of PI3K/Akt signaling and EMT process. Thereby, our finding might shed a new light on exploring the strategies for the treatment of NSCLC.