STK4 is a prognostic biomarker correlated with immune infiltrates in clear cell renal cell carcinoma

BACKGROUND

Mammalian STE20-like kinase 1 (MST1/STK4/KRS2) is a highly conserved serine/threonine kinase and a central member of the Hippo signaling pathway. STK4 has been reported to play important roles in various tumors, but a systematic and comprehensive study of its function in clear cell renal cell carcinoma (ccRCC) has not been conducted.

METHODS

In this study, we used immunohistochemistry (IHC), western blot (WB), quantitative real-time PCR (qPCR) experiments, and bioinformatics analysis to comprehensively analyze the expression, prognostic value, and immune infiltration of STK4 in ccRCC.

RESULTS

Analysis of the TCGA database showed that the expression level of the STK4 gene in ccRCC patients depended on tumor stage, grade, and distant lymphatic metastasis. This was further confirmed by the results of IHC, WB, and qPCR. In addition, we used the receiver operating characteristic curve (ROC curve) to elucidate the diagnostic value of STK4 in ccRCC patients. According to the findings of the TIMER database, the high expression of STK4 is significantly associated with the survival of kidney cancer (including ccRCC) patients (p < 0.001), suggesting that STK4 is a reliable prognostic predictor. We then used gene set enrichment analysis (GSEA) to explore the mechanisms behind STK4 function in ccRCC. We found that STK4 may play a role in immune regulation interactions. Subsequently, we performed immune infiltration analysis of STK4. The results showed that STK4 may regulate the development of ccRCC by affecting the immune infiltration of NK and pDC cells.

CONCLUSIONS

STK4 may be a prognostic marker for ccRCC and may help identify new strategies for treating ccRCC patients.

Prognostic value of sirtuin family members and experimental verification identify SIRT5 as diagnostic biomarkers in clear cell renal cell carcinoma

Background

The sirtuins (SIRTs) family is a nicotinamide adenine dinucleotide (NAD+) family of dependent deacetylases, which includes SIRT1-7. This family is related to the development and progression of various tumors. However, a comprehensive analysis of the role of SIRTs in clear cell renal cell carcinoma (ccRCC) is still lacking, and there are few reports on the inhibitory role of SIRT5 in ccRCC.

Methods

We used immunohistochemical analysis, and several bioinformatic databases to perform an integrated analysis of the expression and prognostic value of SIRT5 and other SIRT family members in ccRCC along with the associated immune cell infiltration. These databases include TIMER, THPA, cell culture, UALCAN, cBioPortal, WebGestalt, Metascape, DiseaseMeth, STRING database, and Cytoscape.

Results

The protein expression of SIRT1, 2, 3, 6, and 7 were upregulated in ccRCC for the Human Protein Atlas database, whereas the expression of SIRT4 and SIRT5 was decreased. The expression based on tumor stage, and grade followed a similar trend. Kaplan-Meier analysis showed that high SIRT4 and SIRT5 expression was positively related to better overall survival (OS), whereas SIRT6 and SIRT7 expression was positively related to worse OS. Further, high SIRT3 expression was related to worse relapse-free survival (RFS), whereas high SIRT5 expression was related to better RFS. To explore the mechanism underlying the function of SIRTs in ccRCC, we also used several databases to perform the functional enrichment analysis and explore the relationship between infiltrating immune cells and seven SIRT family members in ccRCC. The results showed that several SIRT family members, and particularly SIRT5, are correlated with the infiltration of some important immune cells. The protein expression of SIRT5 was significantly lower in tumor tissue compared to normal tissue and was negatively related to the age of the patient ccRCC individual tumor stages, and grades. In human ccRCC samples, strong IHC staining expression of SIRT5 was displayed in adjacent normal tissue than in tumor tissues.

Conclusion

SIRT5 may be a prognostic marker and a novel strategy for the treatment of ccRCC.

Comparative analysis of shell color variety and genetic structure among five high-quality freshwater pearl mussel populations

Four Hyriopsis cumingii populations, a breeding population (BP), a cultured population (FP), two wild populations from Poyang Lake (PY) and Dongting Lake (DT), and an H. schlegelii population were collected (JX), and the first filial generations (F1) were bred synchronously. The shell nacre polymorphisms, population genetic diversity, and genetic structures of the F1 of each population were analyzed and compared using CIELAB colorimetric measurements and microsatellite markers. The color parameters of the shell nacre (L*, a*, dE*) in the BP were significantly different from those in the FP, PY, and JX populations (P < 0.05), whereas the shell nacre color did not differ significantly between the left and right sides of the shells within the same population (P > 0.05). The BP had relatively darker nacre at the posterior end of the shell, and the color parameters (L*, a*, b*, and dE*) differed significantly from those at the front end (P < 0.05). The five populations showed relatively high levels of genetic diversity (H_O = 0.733-0.829). The genetic distance between the H. cumingii populations and H. schlegelii was the greatest, whereas that within the H. cumingii populations and between the FP and the PY population was the smallest. All the individuals tested in this study were optimally grouped into four theoretical populations. In conclusion, the BP was significantly different from the base populations of PY and DT in terms of genetic background and phenotypic parameters of shell nacre color, with potential for further genetic improvement.

Characterization and functional analysis of a chitin synthase gene (HcCS1) identified from the freshwater pearlmussel Hyriopsis cumingii

The triangle sail mussel, Hyriopsis cumingii, is the most important freshwater pearl mussel in China. However, the mechanisms underlying its chitin-mediated shell and nacre formation remain largely unknown. Here, we characterized a chitin synthase (CS) gene (HcCS1) in H. cumingii, and analyzed its possible physiological function. The complete ORF sequence of HcCS1 contained 6903 bp, encoding a 2300-amino acid protein (theoretical molecular mass = 264 kDa; isoelectric point = 6.22), and no putative signal peptide was predicted. A myosin motor head domain, a CS domain, and 12 transmembrane domains were found. The predicted spatial structures of the myosin head and CS domains were similar to the electron microscopic structure of the heavy meromyosin subfragment of chicken smooth muscle myosin and the crystal structure of bacterial cellulose synthase, respectively. This structural similarity indicates that the functions of these two domains might be conserved. Quantitative reverse transcription PCR results showed that HcCS1 was present in all detected tissues, with the highest expression levels detected in the mantle. The HcCS1 transcripts in the mantle were upregulated following shell damage from 12 to 24 h post-damage, and they peaked (approximately 1.5-fold increase) at 12 h after shell damage. These findings suggest that HcCS1 was involved in shell regeneration, and that it might participate in shell and nacre formation in this species via chitin synthesis. HcCS1 might also dynamically regulate chitin deposition during the process of shell and nacre formation with the help of its conserved myosin head domain.

Cloning and expression analysis of the 37-kDa laminin receptor precursor gene from Hyriopsis cumingii

Hyriopsis cumingii is an economically important freshwater pearl mussel with high pearl quality that is endemic in China. Investigation of genes relevant to shell formation is important for increased pearl output. The substances that form mollusk shells are secreted by epithelial cells in the mantle, the proliferation of which influences secretion ability. This study focused on the proliferation-related 37-kDa laminin receptor precursor (37LRP) of H. cumingii. The full-length cDNA (1133 bp) encoding this 300-amino acid protein was cloned from the mantle. Quantitative fluorescence analysis showed that 37LRP expressed in eight tissues, with the highest expression observed in the liver, and its expression pattern in the mantle reflected shell repair. During repair, 37LRP expression was higher in the experimental shell repair group than that in the control group, exhibiting an initial increase followed by a decrease in expression, and returning to basal levels on completion of the repair. A similar trend was also observed with respect to immunity and cellular metabolism. Expression of the 37LRP protein in the experimental group was significantly higher than that in the control group at the first and second days after shell injury. After 4 days, 37LRP expression in the experimental group was lower than that in the control group. In situ hybridization revealed a strong positive signal corresponding to the 37LRP mRNA at the horny grooves of the mantle, evagination, and in epithelial cells of the velum, which implicated these areas in the repair and formation of the cuticle, prismatic layer, and nacre.