To examine the effects of standardized (reference) tobacco preparations on human 
oral cavity cells, two oral squamous cell carcinoma cell lines (101A, 101B) and 
normal human gingival epithelial cells (HGEC) were treated with cigarette smoke 
total particulate matter (TPM), smokeless tobacco extracted with complete 
artificial saliva (ST/CAS), or whole-smoke conditioned media (WS-CM). EC-50 
values, as determined by sulforhodamine B assays, varied among the cell types 
and agents. When normalized to nicotine content, cytotoxicity for WS-CM and TPM 
was higher compared to that observed with ST/CAS. Nicotine alone had no or only 
minimal cytotoxicity for all cell types in the applied range. Activation of 
pro-apoptotic caspase-3 was examined in all cell types at their respective EC-50 
doses for the three agents. TPM, but not ST/CAS or WS-CM significantly activated 
caspase-3 in all three cell types. Fluorescence-activated cell sorting (FACS) 
for expression of the early apoptosis marker Annexin V and for nuclear staining 
by 7-aminoactinomycin (7-AAD) revealed different extents of apoptosis versus 
non-apoptotic cell death for the three agents. These data characterize 
differential responses of normal and malignant oral cells after exposure to TPM, 
ST/CAS, or WS-CM. They assist in understanding differential effects of 
combustible versus non-combustible tobacco products, and in identifying novel 
biomarkers for tobacco smoke exposure and effect in the oral cavity.