Abstrakt

Bcl-2 chromosomal translocation t(14;18) in lung cancer tumors and lung biopsy specimens.

Zahra Farsad, Roya Farzanegan, Neda Doozandeh, Mohammad Behgam Shadmehr, Reza Sheikhnead*

BCL-2 gene amplification not only found in non-Hodgkin’s lymphomas but has been also reported in Small Cell Lung Cancers (SCLC). It has been demonstrated that BCL-2, the founding pro-survival BCL-2 family member is highly expressed in 65% of cases. The expression of BCL-2 was generally higher in SCLC cell lines than other solid tumor cell lines including NSCLC. Tumoral tissues were obtained from 45 lung cancer patients, who underwent curative surgery from 2009 to 2011 at Masih Daneshvari Hospital, Tehran/Iran. The tissues were snap-frozen in liquid nitrogen and stored at -80°C until use. Most tumors 60%) were Non-Small Cell Lung Cancer (NSCLC) and 40% diagnosed as Typical Carcinoid (T.C). We also received 25 lung biopsies from patients with non-cancerous lung diseases. All DNAs were extracted using QIAamp DNA mini Kit (QIAGENE cat.51304). The DNA was extracted from protease K digested samples, following the manufacturer’s protocol; and the DNA concentration was measured by Spectrophotometer. To detect the bcl-2 t(14;18) translocation, the PCR-amplifiable mixture contained 5 μl=500 ng dissected DNA; 3 pmol sense primer for the Mbr (5′-GAGAGTTGCTTTACGTGGCC-3′) or for the mcr (5′-CGCTTGACTCCTTTACGTGC-3′); 3 pmol antisense primer JH (5′-ACCTGAGGAGACGGTGACC-3′); 12 μl Taq DNA Polymerase Master Mix RED (Amplicon master mix) up to a final volume of 25 μL. We found no translocation at MBR breakpoint in any tumor specimen. But surprisingly 80% of lung tumors showed distinctive bands (600-700 bp) at MCR breakpoint. The biopsies from non-cancerous patients also showed no MBR breakpoint but interestingly, 77% of smokers exhibited MCR breakpoint while non-smokers had no bcl2 translocation at all. We could suggest that bcl2 translocation may be an early event that might influence cancer cell survival once lung cancer is further advanced to late stages. The result could also suggest that smoking might somehow alter the expression of bcl2 oncogene, most definitely causing bcl2 translocation at MCR breakpoint.