Iron-(Fe3+) dependent reactivation of telomerase drives colorectal cancers.

Over-consumption of iron-rich red meat and hereditary or genetic iron overload are associated with increased risk of colorectal carcinogenesis, yet the mechanistic basis of how metal-mediated signaling leads to oncogenesis remains enigmatic. Using fresh colorectal cancer (CRC) samples we identify Pirin, an iron sensor, that overcomes a rate-limiting step in oncogenesis, by re-activating the dormant human-reverse-transcriptase (hTERT) subunit of telomerase holoenzyme in an iron-(Fe3+)-dependent-manner and thereby drives CRCs. Chemical genetic screens combined with isothermal-dose response fingerprinting and mass-spectrometry identified a small molecule SP2509, that specifically inhibits Pirin-mediated hTERT reactivation in CRCs by competing with iron-(Fe3+) binding. Our findings, first to document how metal ions reactivate telomerase, provide a molecular mechanism for the well-known association between red meat, and increased incidence of CRCs. Small molecules like SP2509 represent a novel modality to target telomerase that acts as driver of 90% human cancers and is yet to be targeted in clinic.

A Warhead Substitution Study on the Coronavirus Main Protease Inhibitor Nirmatrelvir.

The SARS-CoV-2 pandemic is currently causing an unprecedented global health emergency since its emergence in December 2019. In December 2021, the FDA granted emergency use authorization to nirmatrelvir, a SARS-CoV-2 main protease inhibitor, for treating infected patients. This peptidomimetic is designed with a nitrile warhead, which forms a covalent bond to the viral protease. Herein, we investigate nirmatrelvir analogs with different warheads and their inhibitory activities. In addition, antiviral activities against human alphacoronavirus 229E was also investigated along with a cell-based assay. We discovered that the hydroxymethylketone and ketobenzothiazole warheads were equipotent to the nitrile warhead, suggesting that these analogs can also be used for treating coronavirus infections.

Downregulation of CRNN gene and genomic instability at 1q21.3 in oral squamous cell carcinoma.

OBJECTIVES: This study includes the direct sequencing of cornulin (CRNN) gene to elucidate the possible mechanism of CRNN downregulation and explore the genetic imbalances at 1q21.3 across oral squamous cell carcinoma (OSCC) samples. MATERIALS AND METHODS: In mutation screening of CRNN gene, gDNA from OSCC tissues were extracted, amplified, and followed by direct sequencing. OSCC samples were also subjected to fragment analysis on CRNN gene to investigate its microsatellite instability (MSI) and loss of heterozygosity (LOH). Immunohistochemistry was performed to validate CRNN downregulation in OSCC samples. RESULTS: No pathogenic mutation was found in CRNN gene, while high frequency of allelic imbalances was found at 1q21.3 region. MSI was found more frequent (25.3 %) than LOH (9.3 %). Approximately 22.6 % of cases had high MSI which reflects higher probability of inactivation of DNA mismatch repair genes. MSI showed significant association with no betel quid chewing (p = 0.003) and tongue subsite (p = 0.026). LOH was associated with ethnicity (p = 0.008) and advanced staging (p = 0.039). The LOH at 1q21.3 was identified to be as an independent prognostic marker in OSCC (HRR = 7.15 (95 % CI, 1.41-36.25), p = 0.018). Downregulation of CRNN was found among MSI-positive OSCCs and was associated with poor prognosis (p = 0.044). CONCLUSION: This study showed a significant correlation between LOH/MSI at 1q21.3 with clinical outcomes and that downregulation of CRNN gene could be considered as a prognostic marker of OSCC. CLINICAL RELEVANCE: Insights of the downregulation mode of CRNN gene lays the basis of drug development on this gene as well as revealing its prognostic value.

Oral cancer secretome: identification of cancer-associated proteins.

This study aims to identify cancer-associated proteins in the secretome of oral cancer cell lines. We have successfully established four primary cell cultures of normal cells with a limited lifespan without human telomerase reverse transcriptase (hTERT) immortalization. The secretome of these primary cell cultures were compared with that of oral cancer cell lines using 2DE. Thirty five protein spots were found to have changed in abundance. Unambiguous identification of these proteins was achieved by MALDI TOF/TOF. In silico analysis predicted that 24 of these proteins were secreted via classical or nonclassical mechanisms. The mRNA expression of six genes was found to correlate with the corresponding protein abundance. Ingenuity Pathway Analysis (IPA) core analysis revealed that the identified proteins were relevant in, and related to, cancer development with likely involvements in tumor growth, metastasis, hyperproliferation, tumorigenesis, neoplasia, hyperplasia, and cell transformation. In conclusion, we have demonstrated that a comparative study of the secretome of cancer versus normal cell lines can be used to identify cancer-associated proteins.

Establishment of HPLC-ESI-MS method for the determination of eplerenone in human plasma and its pharmacokinetics / 药学学报

A sensitive high performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) method was established for the determination of eplerenone (EP) in human plasma. The plasma samples of EP were extracted with ethyl acetate and separated by HPLC on a reversed phase C18 column with a mobile phase of 10 mmol x L(-1) ammonium acetate water solution-methanol (30 : 70, v/v). EP was determined with electrospray ionization-mass spectrometry (ESI-MS) in the selected ion monitoring (SIM) mode. The calibration curves were linear over the range of 2-4 000 ng x mL(-1) for EP. The lower limit of quantification was 2 ng x mL(-1). The method has been successfully applied in the pharmacokinetic study of the EP tablets. The main pharmacokinetic parameters of EP after oral administration of 25 mg, 50 mg, 100 mg were as follows, t1/2: (4.9 +/- 2.1), (4.7 +/- 1.5), (5.9 +/- 1.2) h; AUC(0-infinity): (4 402 +/- 1 735), (8 150 +/- 2 509), (13 783 +/- 4 102) microg x h x L(-1); and MRT: (6.2 +/- 2.1), (6.6 +/- 1.3), and (7.2 +/- 1.6) h. Parameters of EP after oral administration of multiple doses of 50 mg were as follows, t1/2: (6.1 +/- 1.7) h; AUC(ss): (10 071 +/- 4220) microg x h x L(-1); MRT: (8.1 +/- 2.3) h; and DF: (3.2 +/- 1.0).