Expression dynamics of periodic transcripts during cancer cell cycle progression and their correlation with anticancer drug sensitivity.

BACKGROUND: The cell cycle is at the center of cellular activities and is orchestrated by complex regulatory mechanisms, among which transcriptional regulation is one of the most important components. Alternative splicing dramatically expands the regulatory network by producing transcript isoforms of genes to exquisitely control the cell cycle. However, the patterns of transcript isoform expression in the cell cycle are unclear. Therapies targeting cell cycle checkpoints are commonly used as anticancer therapies, but none of them have been designed or evaluated at the alternative splicing transcript level. The utility of these transcripts as markers of cell cycle-related drug sensitivity is still unknown, and studies on the expression patterns of cell cycle-targeting drug-related transcripts are also rare. METHODS: To explore alternative splicing patterns during cell cycle progression, we performed sequential transcriptomic assays following cell cycle synchronization in colon cancer HCT116 and breast cancer MDA-MB-231 cell lines, using flow cytometry and reference cell cycle transcripts to confirm the cell cycle phases of samples, and we developed a new algorithm to describe the periodic patterns of transcripts fluctuating during the cell cycle. Genomics of Drug Sensitivity in Cancer (GDSC) drug sensitivity datasets and Cancer Cell Line Encyclopedia (CCLE) transcript datasets were used to assess the correlation of genes and their transcript isoforms with drug sensitivity. We identified transcripts associated with typical drugs targeting cell cycle by determining correlation coefficients. Cytotoxicity assays were used to confirm the effect of ENST00000257904 against cyclin dependent kinase 4/6 (CDK4/6) inhibitors. Finally, alternative splicing transcripts associated with mitotic (M) phase arrest were analyzed using an RNA synthesis inhibition assay and transcriptome analysis. RESULTS: We established high-resolution transcriptome datasets of synchronized cell cycle samples from colon cancer HCT116 and breast cancer MDA-MB-231 cells. The results of the cell cycle assessment showed that 43,326, 41,578 and 29,244 transcripts were found to be periodically expressed in HeLa, HCT116 and MDA-MB-231 cells, respectively, among which 1280 transcripts showed this expression pattern in all three cancer cell lines. Drug sensitivity assessments showed that a large number of these transcripts displayed a higher correlation with drug sensitivity than their corresponding genes. Cell cycle-related drug screening showed that the level of the CDK4 transcript ENST00000547281 was more significantly associated with the resistance of cells to CDK4/6 inhibitors than the level of the CDK4 reference transcript ENST00000257904. The transcriptional inhibition assay following M phase arrest further confirmed the M-phase-specific expression of the splicing transcripts. Combined with the cell cycle-related drug screening, the results also showed that a set of periodic transcripts, for example, ENST00000314392 (a dolichyl-phosphate mannosyltransferase polypeptide 2 isoform transcript), was more associated with drug sensitivity than the levels of their corresponding gene transcripts. CONCLUSIONS: In summary, we identified a panel of cell cycle-related periodic transcripts and found that the levels of transcripts of drug target genes showed different values for predicting drug sensitivity, providing novel insights into alternative splicing-related drug development and evaluation.

[Association between single nucleotide polymorphisms in the promoter of cyclooxygenase COX-2 gene and hereditary susceptibility to pancreatic cancer].

OBJECTIVE: To evaluate the effects of -1290A > G, -1195G > A and -765G > C single nucleotide polymorphisms (SNPs) in the promoter of cyclooxygenase (COX)-2 gene on the risk of pathogenesis of pancreatic cancer. METHODS: Peripheral blood samples were collected from 283 patients with pancreatic cancer and 566 normal controls. Questionnaire survey was conducted to understand the demographic data and status of smoking and smoking cessation of the subjects. Polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) was used to detect the genotypes of the gene fragments containing the 3 SNP sites in the promoter regions of the COX-2 gene. Statistical tests were performed to analyze the relations among different factors and the risk of pancreatic cancer. RESULTS: Three SNPs, -1290A > G, -1195G > A, and -765G > C were identified. A case-control analysis revealed 1.75-fold (95% CI = 1.16-2.64) and 2.53-fold (95% CI = 1.43-4.47) excesses of risks of developing pancreatic cancer for the -1195AA and -765CG genotype carriers respectively compared with the non-carriers. Compared with A(-1290)-G(-1195)-G(-765) containing haplotype, greater risks of developing pancreatic cancer were observed for A(-1290)-A(-1195)-G(-765), (OR = 1.26, 95%, CI = 1.02-1.56) and G(-1290)-A(-1195)-C(-765) (OR = 5.54, 95% CI = 1.79-17.16) containing haplotypes. There were interactions between the -765CG or -1195AA genotype and smoking in the risk of developing pancreatic cancer. CONCLUSION: The SNP of -1195A > G and -765G > C in the COX -2 promoter may play an important role in mediating hereditary susceptibility to developing pancreatic cancer.

[Diagnosis and management of metastatic pancreatic tumors].

OBJECTIVE: To study the clinicopathological features and prognostic factors of metastatic pancreatic tumor. METHODS: The clinical data of 18 metastatic pancreatic tumors were retrospectively analyzed. The primary foci of these 18 patients included: 8 lung cancer, 2 gastric cancer, and malignant histiocytoma, melanoma, rectal cancer, thyroid cancer, renal cell carcinoma, esophageal carcinoma, liver cancer and ovarian cancer each. RESULTS: All these 18 patients harboring metastatic pancreatic tumor did not show any specific symptoms but were frequently found to have a solitary (14 cases) or multiple (4 cases) homogeneous and hypodense nodules on CT scan without any enhancement except one metastatic renal cell carcinoma. The diagnosis was cytologically confirmed in 14 patients by fine needle aspiration biopsy guided by CT or ultrasonography, and diagnosed by postoperative pathology in the other 4 patients. After receiving combined modality treatment, their survival time was 8 to 38 months with an average of 19 months. CONCLUSION: Metastatic pancreatic tumors are rare and give no specific symptom or image finding. Selection of appropriate combined modality treatment according to the type of primary focus is very important for the management.

[Clinicopathological characteristics and prognosis of remnant stomach cancer--report of 45 cases].

OBJECTIVE: To investigate the clinicopathological characteristics and prognostic factors of remnant stomach cancer. METHODS: The clinicopathological and prognosis data of 45 patients with remnant stomach cancer were retrospectively analyzed. RESULTS: The remnant stomach cancer are likely to develop in males with a ratio of male to female: 44:1. Their initial operation modes of these patients were Billroth II subtotal gastrectomy in 40 patients, Billroth I subtotal gastrectomy in 4 and proximal subtotal gastrectomy in 1. The interval from the initial operation to the diagnosis of remnant stomach cancer was 5 to 42 years with an average of 23 years. Of these 45 patients, 28 had lesion at anastomotic site, 9 in the gastric cardia and 8 in other locations; 19 had radical resection, 16 palliative resection and 10 exploration alone except one who had an anastomosis of remnant stomach with the jejunum. The histology types included: 1 un-differentiated adenocarcinoma, 36 poorly-differentiated adenocarcinoma, 7 moderately-differentiated adenocarcinoma and 1 well-differentiated adenocarcinoma. The 1-, 3-, 5-year survival rates of patients with radical resection were significantly better than those treated with palliative resection, which was 100% vs. 62.5%, 78.8% vs. 25%, 47.2% vs. 0, respectively (P < 0.05). All ten patients without resection died within 2 years with an average survival time of 12 months. The 5-year survival rate of stage I, II, III and IV was 100%, 75%, 17.8% and 0, respectively (P < 0.05). CONCLUSION: Remnant stomach cancer prevalently occurs in the male usually 10 years after Birroth II gastrectomy. The lesions is mainly located at anastomotic site. Poorly-differentiated adenocarcinoma is found to be the prevalent histological type of advanced remnant stomach cancer. The prognosis of remnant stomach cancer is correlated with pTNM stage and whether having been treated with complete resection or not. Patients with early remnant stomach cancer may survive for a long time if radical resection can be done.