Laleh Kamalian

Increased Expression of Id Family Proteins in Small Cell Lung Cancer and its Prognostic Significance

Purpose: To study the molecular pathology of human small cell lung cancer (SCLC), molecular biology approaches were used to identify genes involved in malignant progression of the cancer cells. Experimental Design: Microquantity differential display was used initially to identify genes expressed differentially between normal and malignant cell lines. The differences were verified by Western blot. Immunohistochemical analysis was done on paired normal and malignant lung tissues and on tissues taken by biopsy to assess the expression status of candidate genes and their prognostic significance. Results:Inhibitor of DNA/differentiation (Id)1 gene was up-regulated in SCLC cells. Levels of Id1 in 8 of 10 cell lines were increased by 1.7- to 21.4-fold when compared with the benign cells. A similar increase was also found in levels of Id2 and Id3. On 26 pairs of lung tissues, all four Id proteins were significantly (Wilcoxon Signed Rank Test, P < 0.001-0.005) overexpressed in cytoplasm of the malignant cells. In nuclei of SCLC cells, Id1 expression was significantly reduced, whereas the levels of Id2, Id3, and Id4 were significantly (Wilcoxon Signed Rank Test, P < 0.001) increased. Immunohistochemical staining on biopsy specimens showed that the increased expression of Id2 in cytoplasm of cancer cells, not the other three proteins, was significantly associated with the increased survival of SCLC patients. Conclusion: Changed expression profiles of Id proteins may play important roles in malignant progression of SCLC, and the increased Id2 in cytoplasm is a novel prognostic factor to predict the patient outcomes.

Suppressing tumourigenicity of prostate cancer cells by inhibiting osteopontin expression.

Expression of osteopontin (OPN) is increased in prostate cancer cells. The possibility of utilising the increased OPN as a target to suppress the tumourigenicity was investigated in this study. Small interference RNAs against OPN were transfected into highly malignant DU145 prostate cancer cells, which express high level of OPN prior to the transfections, to establish OPN-suppressed clones. Compared with the control transfectants generated by scrambled RNA, suppressed expression of OPN significantly inhibited cell invasiveness and anchorage-independent growth. Similar results were obtained from in vivo experiments. OPN-suppressed transfectants produced significant reductions in average sizes of subcutaneous tumours after inoculation into nude mice. When the levels of OPN measured in transfectants before injection were related to tumour sizes, the reduction in tumour sizes was not propotionally related to the inhibition in OPN-levels. However, when the levels of OPN were analysed in the tumour tissues, it was found that the reduced OPN expression levels were significantly associated with the reducing tumour sizes. These results showed that changes in OPN levels had occurred after the transfectants were inoculated in mice. This study suggested while OPN can be an effective target for therapeutic suppression of prostate cancer, more effective way than RNAi is needed to inhibit OPN expression.

Identification of the Additional Mitochondrial Liabilities of 2-Hydroxyflutamide When Compared With its Parent Compound, Flutamide in HepG2 Cells

The androgen receptor antagonist, flutamide, is strongly associated with idiosyncratic drug-induced liver injury (DILI). Following administration, flutamide undergoes extensive first-pass metabolism to its primary metabolite, 2-hydroxyflutamide. Flutamide is a known mitochondrial toxicant; however there has been limited investigation into the potential mitochondrial toxicity of 2-hydroxyflutamide and its contribution to flutamide-induced liver injury. In this study we have used the acute glucose or galactose-conditioning of HepG2 cells to compare the mitochondrial toxicity of flutamide, 2-hydroxyflutamide and the structurally-related, non-hepatotoxic androgen receptor antagonist, bicalutamide. Compound-induced changes in mitochondrial oxygen consumption rate were assessed using Seahorse technology. Permeabilization of cells and delivery of specific substrates and inhibitors of the various respiratory complexes provided more detailed information on the origin of mitochondrial perturbations. These analyses were supported by assessment of downstream impacts including changes in cellular NAD+/NADH ratio. Bicalutamide was not found to be a mitochondrial toxicant, yet flutamide and 2-hydroxyflutamide significantly reduced basal and maximal respiration. Both flutamide and 2-hydroxyflutamide significantly reduced respiratory complex I-linked respiration, though 2-hydroxyflutamide also significantly decreased complex II and V-linked respiration; liabilities not demonstrated by the parent compound. This study has identified for the first time, the additional mitochondrial liabilities of the major metabolite, 2-hydroxyflutamide compared with its parent drug, flutamide. Given the rapid production of this metabolite upon administration of flutamide, but not bicalutamide, we propose that the additional mitochondrial toxicity of 2-hydroxyflutamide may fundamentally contribute to the idiosyncratic DILI seen in flutamide-treated, but not bicalutamide-treated patients.

The utility of HepaRG cells for bioenergetic investigation and detection of drug-induced mitochondrial toxicity

The importance of mitochondrial toxicity in drug-induced liver injury is well established. The bioenergetic phenotype of the HepaRG cell line was defined in order to assess their suitability as a model of mitochondrial hepatotoxicity. Bioenergetic phenotyping categorised the HepaRG cells as less metabolically active when measured beside the more energetic HepG2 cells. However, inhibition of mitochondrial ATP synthase induced an increase in glycolytic activity of both HepaRG and HepG2 cells suggesting an active Crabtree Effect in both cell lines. The suitability of HepaRG cells for the acute metabolic modification assay as a screen for mitotoxicity was confirmed using a panel of compounds, including both positive and negative mitotoxic compounds. Seahorse respirometry studies demonstrated that a statistically significant decrease in spare respiratory capacity is the first indication of mitochondrial dysfunction. Furthermore, based upon comparing changes in respiratory parameters to those of the positive controls, rotenone and carbonyl cyanide m-chlorophenyl hydrazone, compounds were categorised into two mechanistic groups; inhibitors or uncouplers of the electron transport chain. Overall, the findings from this study have demonstrated that HepaRG cells, despite having different resting bioenergetic phenotype to HepG2 cells are a suitable model to detect drug-induced mitochondrial toxicity with similar detection rates to HepG2 cells.