Date of Award

12-13-2024

Degree Type

Thesis

Degree Name

MPhil in Biological and Biomedical Sciences

First Advisor

Dr Arooj Shafiq

Second Advisor

Dr Kulsoom Ghias

Third Advisor

Dr Matti-Ur-Rehman

Department

Biological and Biomedical Sciences

Abstract

Objectives: Colorectal cancer (CRC) is the third most common cancer. It is one of the leading causes of cancer-related deaths worldwide. RALA and RALB pathways are the third-best characterized pathway downstream RAS and have emerged as drug targets over the last one decade. This study analyzes CRC tissue samples from 123 patients for KRAS codons 12 and 13 mutations and expression levels of RALAand RALB proteins in relation to demographics, clinical, and survival of patients. The comprehensive analysis is aimed at providing a deeper understanding of the clinical implications and potential therapeutic relevance of these findings in the context of colorectal cancer.
Methods: For this study, 123 formalin-fixed paraffin-embedded (FFPE) CRC tissue samples were collected from Aga Khan University Hospital Karachi, Pakistan, with institutional ERC approval. Patients' clinical and demographic data was collected from hospital records. KRAS mutation in codons 12 and 13 of the CRC tissue samples was analyzed using PCR-RFLP and confirmed by sequencing. Expression of RALA and RALB were assessed using immunohistochemistry (IHC) in tissue microarray format.
Results: The CRC patient cohort had a mean age of 47.66 years with a male predominance. Most cases were diagnosed at advanced stages (III and IV). This represents epidemiological trends toward early-age CRC and late-stage detection. No mutations in KRAS codons 12 and 13 were found in the CRC tissue samples. Immunohistochemical analysis on CRC samples demonstrated a substantial expression of RALA with an average Immunoreactivity Score (IRS) of 6. In contrast, RALB exhibited a lower expression with an average IRS value of 4 in these samples. The expression of RALA and RALB was higher in tumor tissues compared to normal VI tissues. RALB expression also showed greater variability compared to RALA. Kaplan Meier survival curve showed the high expression of RALA and RALB related to the low survival. Correlation analyses showed weak associations between RALA/RALB expression and demographic or pathological factors. RALA showed slightly stronger positive correlations with age, while RALB correlated negatively with disease stage and grade.
Conclusion: These results provide the molecular landscape of the expression of RALA and RALB in CRC among the Pakistani patient cohort Immunohistochemical analysis showed high expression of RALA and RALB in tumor tissues. High RALA expression was also found linked to lower survival, highlighting their potential as prognostic markers in CRC. RALA and RALB expression levels only showed weak associations with demographic or pathological features. However, the study emphasizes the need for further validation studies to confirm these findings with a larger sample size, as well as expanded investigations to elucidate the precise roles of RALA and RALB in CRC pathogenesis and patient outcome.

First Page

1

Last Page

80

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