Benzo[a]pyrene [B(a)P], a well-known environmental carcinogen, promotes oxidative stress and DNA damage.
Thymoquinone (TQ) exhibits promising effects against inflammatory diseases and cancer. The possible protective
and chemopreventive effects of TQ against [B(a)P] -induced lung cancer in mice were investigated. One hundred
male Swiss albino mice divided into four equal groups. Group Ι: (Control) received no drugs. Group Π:(lung cancerinduced)
mice injected with a single dose of [B(a)P] (100 mg/ kg b.wt, i.p). Group III: (lung cancer + TQ treated)
mice injected with [B(a)P] as in group II and treated with TQ (20 mg/kg b.wt/day, orally) from 22th week to 30th
weeks. Group IV: (lung cancer + TQ protected) mice received TQ (20 mg/kg b.wt. / Orally) on alternate days from 1
day prior to [B(a)P] injection and were treated continuously with TQ until 30th week. Blood samples and lung tissue
for determination of serum CEA, Haptoglobin (HPT), ADA and ɤ-GT in addition to enzymatic antioxidants status
(CAT, SOD, GPx, GST and GR), L-MDA, NO, GSH, Bcl-2, CYP1A1, P53, Caspase 3, DNA fragmentation and COX-2 in lung
tissues. The obtained results revealed that, [B(a)P] potentially increased serum CEA, HPT, ADA, ɤ- GT in addition to
COX-2, Caspase 3, L-MDA, NO, Bcl-2, CYP1A1, P53, and DNA fragmentation in lung tissues. However, antioxidant
enzymes activities and GSH were markedly decreased. It could be concluded that, TQ mitigate lung cancer through
its radical scavenging activity and anti-inflammatory effect, regenerating endogenous antioxidant mechanisms and
attenuated the increased caspase 3, DNA fragmentation, COX-2, Bcl-2, CYP1A1, P53 and oxidative stress in lung
tissues. These results suggest that, the possible efficiency of TQ as a distinct chemo-preventive agent in lung
carcinogenesis.