Tea Intake and Squamous Cell Carcinoma of the Skin: Influence of Type of Tea Beverages
Iman A. Hakim2,Robin B. Harris and Ute M. Weisgerbe Cancer Prevention and Control, Arizona Cancer Center, College of Medicine, University of Arizona, Tucson, Arizona 85724 [I. A. H., R. B. H.], and Unilever Health Institute Vlaardingen, 3130 AC Vlaardingen, the Netherlands [U. M. W.]
Differences in tea drinking habits are likely to vary by populations and
could contribute to the inconsistencies found between studies comparing
tea consumption and cancer risk. A population-based case-control study
was used to evaluate how usual tea consumption patterns of an older
population (n = 450) varied with history of
squamous cell carcinoma (SCC) of the skin. A detailed tea questionnaire
was developed to assess specific tea preparation methods and patterns
of drinking. In this southwestern United States population, black tea
was the predominant variety of tea consumed. We found no association
between the broad definition of any tea consumption and skin SCC.
However, the adjusted odds ratios (ORs) for hot and iced black tea
intake were 0.63 [95% confidence interval (CI), 0.36–1.10] and 1.02
(95% CI, 0.64–1.63), respectively. Controls were more likely to
report usually drinking strong hot tea (OR, 0.74; 95% CI, 0.53–1.03)
with increased brewing time (P for trend = 0.03).
Adjusting for brewing time, the association between skin SCC and hot
black tea consumption suggests a significantly lower risk in consumers
of hot tea compared to nonconsumers (OR, 0.33; 95% CI, 0.12–0.87).
This is one of the first studies to explore the relation between
different types of tea consumption and occurrence of human cancers. Our
results show that tea concentration (strength), brewing time, and
beverage temperature have major influences on the potential protective
effects of hot black tea in relation to skin SCC. Further studies with
increased sample sizes are needed to evaluate the interrelationships
between preparation techniques, tea type, and other life-style factors
Apoptogenic effects of black tea on Ehrlich’s ascites carcinoma cell
Arindam Bhattacharyya, Tathagata Choudhuri, Suman Pal, Sreya Chattopadhyay, Goutam K. Datta, Gaurisankar Sa and Tanya Das1
Bose Institute, P-1/12 CIT Scheme VII M, Kolkata-700 054, India
Next to water, tea is the most ancient and widely consumed beveragein the world. Epidemiological studies have suggested a cancer protective effect, but the results obtained so far are not conclusive.In the current study, mechanisms of the apoptogenic effect of black tea extract were delineated. Black tea administration to Ehrlich’s ascites carcinoma (EAC)-bearing Swiss albinomice caused a significant decrease in the tumor cell count ina dose-dependent manner. Flow ytometric analysis showed an increase in the number of cells in the sub-G0/G1 population signifying tumor cell apoptosis by black tea. These results were further confirmed by nuclear staining that demonstrated distinct morphological features of apoptosis. Our data also revealed an increase inthe expression of pro-apoptotic protein p53 in EAC. It is knownthat upon p53 induction, multiple downstream factors contribute to the decision making between growth arrest and apoptosis.Among those, pro-apoptotic gene Bax is up regulated during p53-mediated apoptosis. On the other hand, p53-mediated growth arrest involvesp21 as a major effecter. In our system, increase in p53 expression was followed by moderate expression of p21/Waf-1 and high expression of Bax at protein levels. Interestingly, anti-apoptotic protein Bcl-2 was down regulated resulting in decrease in Bcl-2/Baxratio. All these observations together signify that black tea-induced apoptogenic signals overrode the growth-arresting message of p21, thereby leading the tumor cells towards death.