FHIT protein enhances paclitaxel‐induced apoptosis in lung cancer cells

Abstract

The fragile histidine triad (FHIT) gene is a frequent target of deletions in lung cancer. Previous studies have shown that FHIT gene transfer into lung cancer cells lacking FHIT expression results in induction of apoptosis. However, the effect of FHIT expression on apoptosis induced by chemotherapeutic agents and its intracellular mechanism is poorly understood. This study was undertaken to elucidate the effect of FHIT expression and the role of Bcl-2-caspase signaling in paclitaxel-induced apoptosis in lung cancer cells. NCI-H358 lung cancer cells, which lack FHIT expression, were stably transfected with plasmid vector containing FLAGtagged wildtype FHIT. We investigated effects of paclitaxel on apoptosis, activation of caspase system and expression of Bcl-2 family. We next evaluated whether these effects were reversed by blocking FHIT expression using siRNA. Paclitaxel enhanced apoptosis in FHIT-expressing cells compared to that in control vectortransfected cells, and this enhancement was suppressed by siRNA treatment. Activities of caspase-3 and caspase-7, but not of caspase-8, were higher in FHIT-expressing cells than in control vector-transfected cells, and this was reduced by siRNA treatment. When caspase activation was blocked by a pan-caspase inhibitor in FHIT-expressing cells, paclitaxel-induced apoptotic cell death was decreased similar to that in control vector-transfected cells. Bcl-2 and Bcl-xL expressions were down-regulated after paclitaxel treatment in FHIT-expressing cells, whereas Bax and Bad expressions were up-regulated. These were reversed by siRNA treatment. These results indicate that paclitaxel-induced apoptosis enhanced by FHIT expression in lung cancer cells might be associated with modulation of Bcl-2-caspase signaling. ' 2005 Wiley-Liss, Inc.Key words: fragile histidine triad (FHIT); paclitaxel; apoptosis; Bcl-2 protein; lung neoplasms Deletion of human chromosome 3p is one of the most frequently found genetic alterations in lung cancers, observed in more than 90% of small cell lung cancers and in about 80% of non-small cell lung cancers. [1][2][3][4] Further, it is known that chromosome 3p deletions occur even in an early stage of lung carcinogenesis including hyperplasia, dysplasia or carcinoma in situ. 5,6 Thus, chromosome 3p has been proposed to contain tumor suppressor genes of lung cancer, and several candidate genes have been identified. 7-10 The fragile histidine triad (FHIT) gene is located at 3p14.2 11 and its gene product, FHIT protein, is a diadenosine triphosphate (Ap3A) hydrolase belonging to the histidine triad superfamily of nucleotide-binding proteins. 12,13 Numerous studies have shown the FHIT gene is a frequent target of deletions associated with abnormal RNA and protein expression in primary tumors and cell lines of lung, esophageal, head and neck, cervical and breast cancer. [14][15][16][17] In lung cancer, FHIT inactivation has been detected very frequently. [18][19][20] For example, 80% of small cell lung cancers and 40% of non-small cell lung cancers showed abn...

Fhit Delocalizes Annexin A4 from Plasma Membrane to Cytosol and Sensitizes Lung Cancer Cells to Paclitaxel

“…It was previously demonstrated that the absence of Fhit protein in cancer cells resulted in resistance to paclitaxel [28]; Annexin 4, a protein with both plasma membrane and cytoplasmic localization, has been reported to be overexpressed in many cancer cells; in particular, it has been demonstrated that Annexin 4 over-expression contributes to cancer cells resistant to paclitaxel [29]. Thus, to shed light on the mechanisms of drug resistance in FHIT -minus cancer cells, we decided to focus on Annexin 4 among the freshly identified candidate Fhit partners.…”

Piroxicam and Cisplatin in a Mouse Model of Peritoneal Mesothelioma

“…COX17, a cytochrome c oxidase assembly protein, has been proposed as therapeutic target in lung cancer (45). The fragile histidine triad (FHIT) gene, a frequent target of deletions in lung cancer, and PMS2, a mismatch repair protein, have been shown to enhance paclitaxel-and CDDP-induced apoptosis in cancer cells (46,47). Finally, the human HtrA1, a member of the HtrA family of serine proteases, has been characterized for its effects as a tumor suppressor -like protein (48).…”

Tumor and host factors that may limit efficacy of chemotherapy in non-small cell and small cell lung cancer

“…FHIT increased sensitivity to cisplatin in NSCLC cells that possessed wild type p53 and partially restored sensitivity to cisplatin in resistant cells that overexpressed Bcl-2- and Bcl-x(L)360. FHIT also increased sensitivity of lung cancer cells to paclitaxel in some assessments361, but not in others360. However, transfection of FHIT-negative NSCLC cells with FHIT reduced sensitivity to etoposide, doxorubicin, and topotecan due to Fhit-induced downregulation of DNA topoisomerases I and II360.…”