Saima Shakil Malik1,2, Ayisha Zia3, Sajid Rashid3, Sumaira Mubarik4, Nosheen Masood5, Mubashar Hussain6, Azra Yasmin5, Razia Bano7. 1. Fatima Jinnah Women University, The Mall Rawalpindi, Rawalpindi, Pakistan. saimamalik25@yahoo.com. 2. Department of Zoology, University of Gujrat, Gujrat, Pakistan. saimamalik25@yahoo.com. 3. National Centre for Bioinformatics, Quaid-i-Azam University, Islamabad, Pakistan. 4. Department of Epidemiology and Biostatistics, School of Health Sciences, Wuhan University, Wuhan, China. 5. Fatima Jinnah Women University, The Mall Rawalpindi, Rawalpindi, Pakistan. 6. Department of Zoology, University of Gujrat, Gujrat, Pakistan. 7. Breast Clinic, Combined Military Hospital, Rawalpindi, Pakistan.
Abstract
BACKGROUND: Gene polymorphisms that affect nucleotide excision repair (NER) pathway may link with higher susceptibility of breast cancer (BC); however, the significance of these associations may vary conferring to the individual ethnicity. Xeroderma pigmentosum complementation gene (XPC) plays a substantial role in recognizing damaged DNA during NER process. OBJECTIVE AND METHODS: To estimate the relationship among XPC polymorphisms and breast cancer (BC) risk, we carried out a case-control-association study with 493 BC cases and 387 controls using TETRA-ARMS-PCR. Distributional differences of clinical features, demographic factors and XPC polymorphisms among BC cases and controls were examined by conditional logistic regression model. Kaplan-Meier test was applied to predict survival distributions and protein structure was predicted using computational tools. RESULTS: Obesity, consanguinity, positive marital status and BC family history were associated (P ≤ 0.01) with higher BC risk. Genotyping revealed significant involvement (P ≤ 0.01) of two XPC polymorphisms rs2228001-A > C (OR = 3.8; CI 1.9-7.6) and rs2733532-C > T (OR = 2.6; CI 1.4-5.03) in BC development, asserting them potential risk factors for increased BC incidence. However, no association (P > 0.05) was detected for overall or progression free survival for both XPC polymorphisms possibly due to shorter follow-up time (45 months). As compared to normal XPC structure, pronounced conformational changes have been observed in the C-terminus of XPCQ939K, bearing rs2228001-A > C substitution. In XPCQ939K, two additional α-helices were observed at A292-E297 and Y252-R286, while L623-M630 and L649-L653 helices were converted into loop conformation. CONCLUSION: In conclusion, both XPC polymorphisms confer significant association with increased BC risk. rs2228001 substitution may change the structural and functional preferences of XPC C-terminus, while rs2733532 may have regulatory role thereby leading to potential BC risk.
BACKGROUND: Gene polymorphisms that affect nucleotide excision repair (NER) pathway may link with higher susceptibility of breast cancer (BC); however, the significance of these associations may vary conferring to the individual ethnicity. Xeroderma pigmentosum complementation gene (XPC) plays a substantial role in recognizing damaged DNA during NER process. OBJECTIVE AND METHODS: To estimate the relationship among XPC polymorphisms and breast cancer (BC) risk, we carried out a case-control-association study with 493 BC cases and 387 controls using TETRA-ARMS-PCR. Distributional differences of clinical features, demographic factors and XPC polymorphisms among BC cases and controls were examined by conditional logistic regression model. Kaplan-Meier test was applied to predict survival distributions and protein structure was predicted using computational tools. RESULTS: Obesity, consanguinity, positive marital status and BC family history were associated (P ≤ 0.01) with higher BC risk. Genotyping revealed significant involvement (P ≤ 0.01) of two XPC polymorphisms rs2228001-A > C (OR = 3.8; CI 1.9-7.6) and rs2733532-C > T (OR = 2.6; CI 1.4-5.03) in BC development, asserting them potential risk factors for increased BC incidence. However, no association (P > 0.05) was detected for overall or progression free survival for both XPC polymorphisms possibly due to shorter follow-up time (45 months). As compared to normal XPC structure, pronounced conformational changes have been observed in the C-terminus of XPCQ939K, bearing rs2228001-A > C substitution. In XPCQ939K, two additional α-helices were observed at A292-E297 and Y252-R286, while L623-M630 and L649-L653 helices were converted into loop conformation. CONCLUSION: In conclusion, both XPC polymorphisms confer significant association with increased BC risk. rs2228001 substitution may change the structural and functional preferences of XPC C-terminus, while rs2733532 may have regulatory role thereby leading to potential BC risk.
Entities:
Keywords:
Breast cancer; Overall survival; Progression free survival; Protein structure; XPC polymorphisms