Inhibition of apoptosis through bcl-2 protein expression appears to be specifically associated with promotion of intestinal-type gastric adenocarcinoma but does not appear to be active and/or correlated with tumor progression.
Toward this aim, we analyzed, using immunohistochemistry, the expression of the p53 gene and of its transcriptional target genes bax, bcl2, and waf1 in preinvasive bronchial lesions from 69 patients with lung cancer and in similar lesions from 20 patients with nocancer progression. p53 accumulation occurred with increasing frequency, from 19% in mild dysplasia to 36% in moderate dysplasia and 59% in carcinoma in situ, and was exclusively observed in patients with p53-positive carcinoma.
With long-term I2, mammary tumor tissue became more sensitive to DOX, since a single injection of the lowest dose of DOX (4 mg/Kg) was enough to stop tumor progression and a second DOX4 injection on day 14 caused a significant and rapid decrease in tumor size, decreased the expression of chemoresistance markers (Bcl2 and survivin), and increased the expression of the apoptotic protein Bax and peroxisome proliferator-activated receptor type gamma.
Previous studies further suggest that such phospho-Bcl-2 regulation may influence tumor progression in colorectal and other cancers; however, phosphorylation status of the Ser70 of Bcl-2 (pSer70) in vivo in tumors remains obscure.
Typically, 1q21-23 rearrangements arise during tumor evolution and accompany disease-specific chromosomal rearrangements such as t(14;18) (BCL2) and t(8;14) (MYC), where they are thus thought to play an important role in tumor progression.
Abnormal bcl-2 immunoreactivity in 1), the earliest precursor dysplastic lesions and its persistence throughout neoplastic progression and 2), contiguous morphologically unaltered nondysplastic epithelium suggests that bcl-2 alterations occur early during the morphological and molecular sequence of events leading to gastrointestinal epithelial neoplasia.
The frequency of apoptosis in colorectal neoplasia appears to increase in the course of tumor progression in association with a decline in bcl-2 expression, but is not influenced by p53 gene mutations.
Moreover, the enhanced expression and/or activities of some drug resistance-associated molecules such as Bcl-2, Akt/molecular target of rapamycin (mTOR), nuclear factor-kappaB (NF-κB), hypoxia-inducible factors (HIFs), macrophage inhibitory cytokine-1 (MIC-1) and ATP-binding cassette (ABC) multidrug transporters frequently occur in cancer cells during cancer progression and metastases.