Progression of the tumor in a patient with a gastrointestinal stromal tumor with the PDGFRA exon 12 mutation who received multiple surgeries and multiple lines of tyrosine kinase inhibitor therapies: a case report.

Background: Targeted therapy with tyrosine kinase inhibitors (TKIs) benefits most patients with stromal tumors; however, the effects of TKIs in patients with rare cases of gastrointestinal stromal tumors (GISTs) with platelet-derived growth factor receptor alpha (PDGFRA) exon 12 mutations are unclear. Our report of a case treated with multiline TKIs (included ripretinib) may provide some experience into the future management of rare GIST with PDGFRA 12 exon mutation. Case Description: We report the case of a patient (42-year-old female) with a PDGFRA exon 12-mutated GIST who underwent multiple surgeries and multiple lines of TKI therapy. This patient had intra-abdominal recurrence after imatinib, which was used as the 1st-line targeted drug treatment for 7 months after radical surgery, and had widespread metastases in the abdominal cavity after sunitinib, which was used as the 2nd-line targeted drug treatment for 6 months after the second radical surgery. For this advanced GIST patient with extensive intraperitoneal metastasis and rare PDGFRA 12 exon mutation, we then selected ripretinib as the 3rd-line targeted drug therapy to treat the patient. Up to the last follow-up in September 2021, the patient continued to take drugs without obvious complaints of discomfort or adverse events. Conclusions: This case showed that patients with PDGFRA exon 12-mutated GISTs are less likely to benefit from current conventional TKIs, and ripretinib treatment should be considered preferred to regorafenib or even sunitinib according to each patient's situation. However, the limitation of our case is that the patient's second recurrent lesion was not genetically tested to determine the presence of secondary mutation. Further, if a patient's tumor has a high risk of adverse biological behaviors, such as high mitotic figures, vascular tumor thrombus, succinate dehydrogenase B (SDHB) was negative, and regional lymph node metastasis, consideration should be given to shortening the postoperative follow-up interval to 2 months or even 1 month.

Effect of KLF17 overexpression on epithelial-mesenchymal transition of gastric cancer cells.

OBJECTIVE: To investigate Krüppel-like factor 17 (KLF17) expression in normal and gastric cancer tissues and cell lines. METHODS: Levels of KLF17 mRNA and protein in GES-1 normal gastric mucosal cells, and NCI-N87, SGC-7901, BGC-823 and HGC-27 gastric cancer cells were analysed by quantitative polymerase chain reaction (qPCR) and western blot. Differences in KLF17 expression between gastric cancer and adjacent tissues were analysed by qPCR and immunohistochemistry. Invasion/migration effects of KLF17 overexpression in BGC-823 and HGC-27 cells were analysed by wound-healing and Transwell chamber assays. Changes in expression of KLF17 and epithelial-mesenchymal transition (EMT)-related genes (matrix metalloproteinase [MMP]-9, vimentin and E-cadherin) were analysed in BGC-823 and HGC-27 cells before and after transfection using qPCR and western blot. Transforming growth factor (TGF)-ß1, Smad family member (Smad)2/3 and phosphorylated-Smad2/3 levels in BGC-823 and HGC-27 cells were assessed by qPCR and western blot. RESULTS: KLF17 expression was lower in gastric cancer versus adjacent tissues, and in gastric cancer cell lines versus GES-1 normal gastric mucosal cells, and was positively correlated with degree of cancer-cell differentiation. Wound-healing and Transwell assays showed decreased migration and invasion ability of BGC-823 and HGC-27 cells transfected to overexpress KLF17. KLF17 overexpression was associated with decreased MMP-9 and vimentin in BGC-823 and HGC-27 cancer cells, and increased KLF17 and E-cadherin. KLF17 overexpression also resulted in decreased levels of TGF-ß1 and p-Smad2/3 in BGC-823 and HGC-27 cancer cells. CONCLUSION: KLF17 is poorly expressed in gastric cancer tissues and cell lines. KLF17 overexpression might inhibit EMT via the TGF-ß/Smad pathway, thereby reducing gastric cancer cell invasion and migration. Therefore, KLF17 may become a novel target for treating gastric cancer.

Krüppel-like factor 1 serves as a facilitator in gastric cancer progression via activating the Wnt/ß-catenin pathway.

Krüppel-like factor 1 (KLF1) is a transcription factor that exhibits promoting effect in cervical cancer, but its correlation with gastric cancer (GC) has not been reported yet. In this study, we explored the role and potential mechanism of KLF1 in GC progression by using a series of experimental methods including RT-qPCR, Western blot, CCK-8 assay, EdU staining, and cell cycle analysis. KLF1 was found to be elevated in GC tissues (n=415) compared with the normal tissues by applying UALCAN to analyze datasets from The Cancer Genome Atlas (TCGA). The upregulation of KLF1 was also validated in GC cell lines. Functional studies proved that RNA interference-mediated silencing of KLF1 inhibited GC cell growth, as evidenced by the decreased cell viability, DNA synthesis, and arrested cell cycle in G1 phase. Moreover, KLF1 knockdown exerted the inhibitory effects on cell migration and invasion as well as the epithelial-mesenchymal transition (EMT) in GC cells. Conversely, overexpression of KLF1 had the opposite effects on GC progression. Furthermore, we proved that the activation of Wnt/ß-catenin pathway was markedly inhibited by KLF1 knockdown and promoted by KLF1 overexpression. The blockade of Wnt/ß-catenin pathway rescued the effects of KLF1 overexpression. These results suggested that KLF1 promoted the growth, migration, invasion, and EMT process in GC cells, and this promotion was achieved by activating the Wnt/ß-catenin pathway. This work will be helpful for searching the potential therapeutic targets for treatment of GC.

Up-regulation of KLF17 expression increases the sensitivity of gastric cancer to 5-fluorouracil.

It has been reported that the expression of Krüppel-like factor 17 (KLF17) was associated with the occurrence, development, invasion, metastasis and chemotherapy resistance of various tumors. However, the detailed mechanisms by which KLF17 promotes chemotherapy resistance in gastric cancer (GC) have not been fully investigated. In the present study, we collected the GC tissues and non-tumor tissues (matched adjacent normal tissues with corresponding GC tissues) of 60 GC patients, used qRT-PCR, Western blot and immunohistochemistry assay to analyze the relationship between the expression of KLF17 and the clinical pathological data of the patients. The effect of KLF17 on the sensitivity of GC cell lines to 5-fluorouracil (5-FU), and the potential mechanism were detected by MTS assay, Flow cytometry assay, and Western blot. Compared with non-tumor tissues, the expression level of KLF17 in GC tissue was significantly down-regulated, and the expression level of KLF17 in GES-1 cell line and GC cell lines also had a similar trend. Down-regulated expression of KLF17 is related to tumor size, invasion, regional lymph node metastasis, and TNM staging. Furthermore, through upregulating the expression of KLF17, the sensitivity of BGC-823 and SGC-7901 cell lines to 5-FU was obviously increased. Mechanistically, upregulation the expression of KLF17 can inhibit the expressions of P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1), and B-Cell lymphoma-2 (BCL-2), which have been reported to be associated with drug resistance and cell proliferation. Collectively, these data implied that KLF17 has the biological effect of inhibiting chemotherapy resistance of GC, and it could be a potential strategy for the GC chemotherapy resistance.

Inhibitory effect of siRNA-Annexin A7 on growth, migration, and invasion in BGC823 cells and gastric cancer xenograftsin nude mice.

OBJECTIVE: To explore the inhibitory effect of siRNA-Annexin A7 on growth, migration, and invasion of transplanted gastric cancer in nude mice. METHODS: The siRNA sequence targeting to human Annexin A7 gene was designed, and based on that a pair of complementary oligonucleotides were synthesized, annealed, and cloned into plasmid pGenesil-1.1 to construct recombinant plasmid siRNA-Annexin A7. Transplanted gastric cancer model was established by injecting s.c. nude mice with human gastric cancer BGC823 cells, and siRNA-Annexin A7 was injected into the tumors formed. The nude mice were observed for clinical manifestation relying on the size and weight of transplanted tumors. The tumor tissue and angiogenesis were examined by pathologic sections. Flow cytometry was used to detect the changes of cell cycle. Western blot and qRT-PCR were used to analyze the expression of PCNA, P27, MMP-2, and TIMP-2. RESULTS: Both the size and weight of transplanted tumors of nude mice injected with siRNA-Annexin A7 were less than those of control groups (P<0.05). The examination of pathologic sections showed that, compared with in the control group, obvious necrosis of tumor cells was observed in siRNA-Annexin A7 group. The cells in stage S were fewer in siRNA-Annexin A7 group than those in the other two groups, while the cells in stage G0/G1 were much more in siRNA-Annexin A7 group. The results of western blot and qRT-PCR confirmed that the expression of PCNA and MMP-2 was down-regulated, whereas the expression of p27 was up-regulated. CONCLUSION: Gastric cancer xenografts were established in nude mice with human gastric cancer BGC823 cells. The volume and weight of tumor were decreased after inhibition of Annexin A7 expression in BGC823 cells. Tumor cells were arranged sparsely after inhibition of Annexin A7 expression in BGC823 cells. The siRNA-Annexin A7 inhibits Annexin A7 expression in transplanted gastric cancer of nude mice, and influences the growth, migration, and invasion of tumors by down-regulating the expression of PCNA and MMP-2, as well as up-regulating the expression of p27.