Background: MDM2 and p53 are involved in a negative feedback loop where p53 regulates MDM2 at the transcriptional level. MDM2, in turn, downregulates p53. This co-ordinated interaction between these proteins is set to play an important role in the regulation of cell cycle progression following DNA damage to cells. The over-expression of both p53 and MDM2 has been reported in various cancers. However there are only few studies discussing the co-expression of MDM2 with p53 in oral squamous cell carcinoma Aim: The purpose of this study was to determine the correlation of co-expression of p53, MDM2, and Ki-67 proteins with clinico-pathological factors in oral squamous cell carcinoma (OSCC) and to conduct a systematic review of the co-expression of p53/MDM2.
Method: This is a retrospective descriptive study and a systematic review. Formalin-fixed paraffinembedded tissues from 45 OSCC cases were stained by immunohistochemistry (IHC) for p53, MDM2, and Ki-67 proteins.
Results: Immuno-reactivity for p53, MDM2, and Ki-67 was seen in 75.6%, 97.8%, and 62.2% cases of OSCC respectively. The co-expression of p53 and MDM2 (p53/MDM2) was detected in 97.1%, however there was no significant correlation between p53 and MDM2 expression. Notably, p53/MDM2 coexpression was significantly associated with tumour differentiation (p-value = 0.045). The Ki-67LI was not significantly associated with neither MDM2 nor p53/MDM2 co-expression (p-value = 0.268, 0.916 respectively).
Conclusion: The expression of MDM2 was not signif icantly associated with p53 expression suggesting that MDM2 expression is mediated by p53-independent pathways or mutated p53 could not induce the expression of MDM2 in this set of OSCCs. The only clinico-pathological parameter that correlates significantly with co-expression of p53/MDM2 is tumour differentiation where it is suggestive that the co-expression of these 2 proteins is indicative of aggressive tumour behavior.
The purpose of this study was to determine the
DNA yield and quality from different non-invasive
sampling methods and to identify the method which
gave the highest DNA yield. Method: Thirty-eight
volunteers had been recruited in this study where
blood, buccal cells and saliva were collected using
various collection techniques. Buccal cells were
collected by 1) cytobrush and 2) saline mouth rinsing
or “swish”. Meanwhile saliva was collected by passive
drooling method. Upon processing the white blood
cell (WBC), buccal cells and saliva samples, DNA
extraction was performed according to the
manufacturer’s protocol. Quantification and quality
(DNA ratio at A260/A280) of the extracted DNA were
determined using NanoDropND-1000®. T-test was
performed to compare means between DNA obtained
from various collection methods. Results: DNA yields
from buccal cells collected with cytobrush, “swish”,
saliva and WBC (mean ± SD) were (8.2 ± 5.9)ng/μl,
(28.2 ± 14.9)ng/μl, (5.9 ± 9.5)ng/μl and (105.3 ±
75.0)ng/μl respectively. Meanwhile the mean DNA
ratio at A260/A280 for cytobrush, “swish”, saliva and
WBC were 2.3, 2.0, 1.7 and 1.8 respectively. Post hoc
test with Bonferroni correction suggested that DNA
yield from “swish” technique exhibited the least mean
different as compared to the DNA extracted from WBC
(p