Abstract:
Cervical cancer is a gynaecologic cancer type that develops in the cervix. Annually
528,000 new cases of cervical cancer are reported with 266,000 deaths, which account
for 8% mortality of all female cancer patients. Infection with specific human
papillomavirus (HPV) types is considered the most severe risk factor for cervical
cancer. In the context of our socioeconomic conditions, an increasing burden of this
disease and high mortality rate prevail in Bangladesh. Although several researches
related to the epidemiology, HPV vaccination, and treatment modalities have been
carried out in our country, any research on mutation locations and frequencies in
cervical cancer in Bangladesh is yet to be done. Among the high number of genes
involved in different signal transduction and cell growth regulation pathways, five
different genomic regions within the top three most frequently mutated genes in
COSMIC database with a key role in the development of cervical cancers were selected
to study mutation frequency in our patients. These genes are EGFR (Epidermal Growth
Factor Receptor), KRAS (Kirsten rat sarcoma), and PIK3CA (phosphatidylinositol-4,5bisphosphate
3-kinase,
catalytic
subunit
alpha).
DNA
from
46
cervical
tissue
samples
were
extracted
and
amplified
by
PCR,
using
1 set
of primers
designed
for
EGFR
and
2
sets
of
primers
designed
for
two
different
regions
of
both
PIK3CA
and
KRAS
gene.
PCR
products
were purified and sequenced through Sanger cycle sequencing strategy. In
silico analysis was done in two steps: nucleotide sequence analysis and its
corresponding amino acid analysis. The mutated protein structures were determined by
homology modelling using SWISS-MODEL. In total, 39 mutations were found in 28
patient samples. Eleven different mutations (23.91%) were found in amplified EGFR
gene fragments, among which 1 was common in seven patient samples. On the other
hand, twenty four different mutations (52.17%) were found in PIK3CA gene fragment
amplicons, among which 2 were found in more than 1 patient. Four mutations (8.7%)
were found in KRAS gene fragment amplified products. Our study shows that except
for KRAS, the frequency of observed mutations in our patients is higher than those
reported earlier in other parts of the world. The study can be used as a basis to build a
mutation database for cervical cancer in Bangladesh. With the possibility of targetable
oncogenic mutations, further exploration can be oriented towards establishing future
diagnostics, personalized medicine decisions, and other pharmaceutical applications for
specific cancer subtypes.
