Background Targeting PLK1 has recently been proven as a viable therapeutic strategy against oesophageal squamous cell carcinom (ESCC). Therefore, this study aimed to explore whether the PLK1 inhibitor BI2536 is able to sensitize ESCC cells to cisplatin (DDP) and determine the underlying mechanisms. Methods Viability, clonogenicity, cell cycle distribution and apoptosis were assessed in ESCC cells treated with BI2536 or DDP alone or in combination. Checkpoint activation was examined by immunoblotting and immunohistochemistry. Xenograft model was used to assess the efficacy of the co-treatment. The expression level of GSDME in tissue samples were examined by immunohistochemistry. Findings We found that the combination of BI2536 and DDP was synergistic in ESCC cells, which induced pyroptosis in ESCC cells at low doses. Mechanistic studies revealed that BI2536 significantly induced DNA damage and impaired the DNA damage repair pathway in DDP-treated cells both in vitro and in vivo . Interestingly, we found that co-treatment with BI2536 and DDP induced pyroptosis in ESCC cells depending on the caspase-3/GSDME pathway. Importantly, our study found that GSDME was more highly expressed in tumour tissue than that in normal adjacent tissues, and could serve as a prognostic factor. Interpretation BI2536 sensitizes ESCC cells to DDP by inhibiting the DNA damage repair pathway and inducing pyroptosis, which provides new information for understanding pyroptosis. Our study also reveals that the PLK1 inhibitor BI2536 may be an attractive candidate for ESCC targeted therapy, especially when combined with DDP for treating the GSDME overexpression subtype. Fund National 973 Program and National Natural Science Fundation of China.
ObjectivesThe present study aims to elucidate the underlying mechanism how PFKP is regulated by BRCA1 and the clinical significance of PFKP in breast cancer. MethodsMEF-BRCA1 4/4 and the wild type counterpart MEF-BRCA1 +/+ cell lines were used to test the sensitivity of glucose depletion in culture medium. Glucose Assay Kit was used to quantify glucose levels in cultural supernatant and cell lysate. Real time PCR was used to measure the mRNA expression levels of genes. Western blot was used to detect protein levels. Chromatin immunoprecipitation was used to verify the bindings between transcription factors and DNA elements. Luciferase reporter assay was performed to determine the transcriptional activity. Histochemistry assay was performed on tissue microarray. ResultsWe found that MEF-BRCA1 4/4 cells consumed more glucose and were more vulnerable to glucose-deprived culture medium. The mRNA profiles and qPCR assay of MEF-BRCA1 4/4 and MEF-BRCA1 +/+ cells revealed that PFKP, the rate-limiting enzyme of glycolysis, was significantly upregulated in MEF-BRCA1 4/4 cells. Consistently, the repressive effects of BRCA1 on PFKP were confirmed by overexpression or knockdown of BRCA1. Moreover, we also demonstrated that PFKP was suppressed by ZBRK1 as well, which was the corepression partner of BRCA1. Mechanistically, we figured out that BRCA1 formed a transcriptional repression complex with ZBRK1 on the promoter of PFKP and consequently restrained its expression. Importantly, the expression levels of PFKP were demonstrated to associate with poor survival of patients with breast cancer.
Autophagy is the main degradation pathway to eliminate long-lived and aggregated proteins, aged or malfunctioning organelles, which is essential for the intracellular homeostasis and prevention of malignant transformation. Although the processes of autophagosome biogenesis have been well illuminated, the mechanism of autophagosome transport remains largely unclear. In this study, we demonstrated that the ninein-like protein (Nlp), a well-characterized centrosomal associated protein, was able to modulate autophagosome transport and facilitate autophagy. During autophagy, Nlp colocalized with autophagosomes and physically interacted with autophagosome marker LC3, autophagosome sorting protein Rab7 and its downstream effector FYCO1. Interestingly, Nlp enhanced the interaction between Rab7 and FYCO1, thus accelerated autophagic flux and the formation of autophagolysosomes. Furthermore, compared to the wild-type mice, NLP deficient mice treated with chemical agent DMBA were prone to increased incidence of hepatomegaly and liver cancer, which were tight associated with the hepatic autophagic defect. Taken together, our findings provide a new insight for the first time that the well-known centrosomal protein Nlp is also a new regulator of autophagy, which promotes the interaction of Rab7 and FYCO1 and facilitates the formation of autophagolysosome.
Objective Solute carrier family 38 (SLC38s) transporters play important roles in amino acid transportation and signaling transduction. However, their genetic alterations and biological roles in tumors are still largely unclear. This study aimed to elucidate the genetic signatures of SLC38s transporters and their implications in esophageal squamous cell carcinoma (ESCC). Methods Analyses on somatic mutation and copy number alterations (CNAs) of SLC38A3 were performed as described. Immunohistochemistry (IHC) assay and Western blot assay were used to detect the protein expression level. MTS assay, colony formation assay, transwell assay and wound healing assay were used to explore the malignant phenotypes of ESCC cells. Immunofluorescence assay was used to verify the colocalization of two indicated proteins and immunopreciptation assay was performed to confirm the interaction of proteins. Results Our findings revealed that SLC38s family was significantly disrupted in ESCC, with high frequent CNAs and few somatic mutations. SLC38A3 was the most frequent loss gene among them and was linked to poor survival and lymph node metastasis. The expression of SLC38A3 was lower in tumor tissues compared to that in normal tissues, which was also significantly associated with worse clinical outcome. Further experiments revealed that depletion of SLC38A3 could promote EMT in ESCC cell lines, and the interaction of SLC38A3 and SETDB1 might lead to the reduced transcription of Snail. Pharmacogenomic analyses demonstrated that fifteen inhibitors were showed significantly correlated with SLC38A3 expression. Conclusions Our investigations have provided insights that SLC38A3 could act as a suppressor in EMT pathway and serve as a prognostic factor and predictor of differential drug sensitivities in ESCC.
The authors regret to point out there was an error in Fig. 2C, in which the images of GSDMD were inadvertently duplicated by using the same Western Blot film with different exposure timepoints by mistake when processing the pictures. A corrected version of Fig. 2C is included below. Furthermore, in the originally published Supplementary Data Fig. 4B, the second comet image was inadvertently duplicated from Fig. 4B due to an unintentional copy error. A corrected version of Supplementary Fig. 4B is included below. Finally, there is a spelling error on Page 248, the second line of the second paragraph of 3.2 "GDMED" should be "GSDMD". No scientific conclusions are affected by these errors.
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