Harnessing information and communication technologies to leverage scarce resources for cancer education, research and practice in developing countries.

In developing countries, low levels of awareness, cost and organizational constraints on access to specialized care contribute to inadequate patient help-seeking behavior. As much as 95% of cancer patients in developing countries are diagnosed at late to end stage disease. Consequently, treatment outcome is dismally poor and a vicious cycle sets in, with public mystification of cancer and the admonishment of cancer medicine as a futile effort, all, to the further detriment of patient help-seeking behavior and treatment engagement. The situation spirals down, when the practice of cancer medicine is not gratifying to the medical practitioner and does not appeal as a medical specialty to those in training. The future of cancer medicine in developing countries thus hinges on the demystification of cancer through positive information, coupled to an effective organization that allows for the optimal use of available resources, facilitates access to specialized care and promotes the flow of knowledge and technology amongst various stakeholders. This paper strives to make a cogent argument and highlight the capital importance of information and communication technologies in organizing and leveraging scarce resources for cancer education, research and practice in developing countries.

A genome-wide expression profile and system-level integration of nuclear factor kappa B regulated genes reveals fundamental metabolic adaptations during cell growth and survival.

A murine lung alveolar carcinoma cell line (WT-Line 1) and its equally tumorigenic but non-malignant derivative transduced with a dominant negative inhibitor of NF-kappaB (mI-kappaB-Line 1), were profiled on the Affymetrix 19000 gene array platform. Two differentially expressed gene clusters were identified and integrated into a functional model. The downregulation of anti-oxidant defenses, in mI-kappaB-Line 1 cells, correlates with high levels of reactive oxygen species (ROS) and ROS damage to cellular macromolecules while the upregulation of metabolic nuclear receptors correlates with an adaptive/survival response, which involves a shift in energy metabolism toward beta-oxidative respiration. Accordingly, mI-kappaB-Line 1 cells are markedly sensitized to pharmacologic inhibition of beta-oxidative respiration. These findings are indicative of compensatory changes that could undermine anti-cancer therapies targeting NF-kappaB.

Inhibition of beta-oxidative respiration is a therapeutic window associated with the cancer chemo-preventive activity of PPARgamma agonists.

We demonstrate expression and coordinate induction of PPARgamma and lipogenic enzymes (HMG-CoA synthase, HMG-CoA reductase and fatty acid synthase) in a murine lung alveolar carcinoma cell line (Line 1) treated with the PPARgamma agonist troglitazone (TRO) [0-100 microM]. We postulate that TRO induces a shift in cellular energy metabolism towards fatty acid oxidation (beta-oxidative respiration). Accordingly, co-treatment with TRO [30 microM] and increasing concentrations of trimetazidine (TMZ) [0.1-3 mM], an inhibitor of beta-oxidation, results in a dose dependent decrease cellular ATP levels and a dose dependent induction of apoptosis. These findings, suggest that inhibition of beta-oxidative respiration is a therapeutic window associated with the cancer chemo-preventive activity of PPARgamma agonists.

The proteosome inhibitor MG132 attenuates retinoic acid receptor trans-activation and enhances trans-repression of nuclear factor kappaB. Potential relevance to chemo-preventive interventions with retinoids.

BACKGROUND: Nuclear factor kappa B (NFkappaB) is a pro-malignant transcription factor with reciprocal effects on pro-metastatic and anti-metastatic gene expression. Interestingly, NFkappaB blockade results in the reciprocal induction of retinoic acid receptors (RARs). Given the established property of RARs as negative regulators of malignant progression, we postulated that reciprocal interactions between NFkappaB and RARs constitute a signaling module in metastatic gene expression and malignant progression. Using Line 1 tumor cells as a model for signal regulation of metastatic gene expression, we investigated the reciprocal interactions between NFkappaB and RARs in response to the pan-RAR agonist, all-trans retinoic acid (at-RA) and the pan-RAR antagonist, AGN193109. RESULTS: At-RA [0.1-1 microM] dose-dependently activated RAR and coordinately trans-repressed NFkappaB, while AGN193109 [1-10 microM] dose-dependently antagonized the effects of at-RA. At-RA and AGN193109 reciprocally regulate pro-metastatic matrix metalloprotease 9 (MMP 9) and its endogenous inhibitor, the tissue inhibitor of metalloprotease 1 (TIMP 1), in a manner consistent with the putative roles of NFkappaB and RAR in malignant progression. Activation of RAR concurs with its ubiquitination and proteosomal degradation. Accordingly, the proteosome inhibitor, MG132 [5 microM], blocked RAR degradation, quelled RAR trans-activation and enhanced RAR trans-repression of NFkappaB. CONCLUSION: We conclude that reciprocal interactions between NFkappaB and RARs constitute a signaling module in metastatic gene expression and malignant progression and propose that the dissociative effect of proteosome inhibitors could be harnessed towards enhancing the anticancer activity of retinoids.

The mevalonate synthesis pathway as a therapeutic target in cancer.

Farnesyl transferase inhibitors have emerged as bona fide anticancer agents whereas the development of geranylgeranyl transferase inhibitors has been mitigated by overt systemic toxicities. Evidence suggests that the therapeutic value of farnesyl transferase inhibitors is an indirect result of perturbations in the function of geranylgeranylated Rho proteins. To address this question, we used inhibitors of the mevalonate synthesis pathway to decrease cellular levels of farnesly and geranylgeranly isoprenoids and supplemented our culture systems with exogenous isoprenoids accordingly. Using a murine lung alveolar carcinoma cell line (Line 1), we report a dose-dependent inhibition of tumor cell proliferation, adhesion and invasiveness, in response to alendronate (3-30 micromol/L) and mevastatin (1-10 micromol/L). Supplementation of cultures with geranylgeranyl pyrophosphates (100 micromol/L) was observed to rescue drug-induced phenotypic changes whereas farnesyl pyrophosphate (100 micromol/L) had a minimal effect. Our observations highlight the mevalonate synthesis pathway as a target for anticancer therapies and suggest a greater role for geranylgeranylated proteins in cellular processes germane to cancer.

NFkappaB: a pivotal transcription factor in prostate cancer metastasis to bone.

Prostate cancers frequently metastasize to bone and this accounts for substantial morbidity. We investigated the potential role of the transcription factor NFkappaB as a central regulator of prostate cancer metastasis using the prostate adenocarcinoma cell line, PC-3, in a series of in vitro studies. Wild type PC-3 cells (PC-3.WT) have high basal levels of NFkappaB signaling, otherwise absent in PC-3 cells stably expressing a mutant form of the inhibitory kappa B (IkappaB) protein alpha (PC-3.mIkappaB). Although PC-3.WT cells in co-culture with rat bone marrow cells enhance bone resorption, no increase was observed in co-cultures with PC-3.mIkappaB cells. Similarly, although PC-3.WT cells were invasive in a chicken chorioallantoic membrane extravasation model, PC-3.mIkappaB cells lose this capacity to invade. NFkappaB reciprocally regulated genes involved in cellular invasion, with upregulation of MMP-9 and downregulation of its inhibitor, TIMP-1 in PC-3.WT cells, whereas MMP-9 was downregulated and TIMP-1 was upregulated in PC-3.mIkappaB cells. Finally, high basal gene and protein expression of the osteoclast-activating cytokine IL-6, observed in PC-3.WT cells, was absent in PC-3.mIkappaB cells. These in vitro experiments suggest NFkappaB as an important target to prevent prostate cancer bone metastasis and provide a rationale for further study of this transcription factor in metastatic disease.

Clinical relevance of increased retinoid and cAMP transcriptional programs in tumor cells rendered non-malignant by dominant negative inhibition of NFkappaB.

We previously reported reciprocal regulation of extracellular matrix degrading enzymes and their endogenous inhibitors by NFkappaB. As such, dominant negative inhibition of NFkappaB in a murine lung alveolar carcinoma cell, Line 1, afforded a decrease in malignant proclivity [Cancer Res. 60(23) (2000) 6557-6562]. Contrasting the gene expression profile of malignant Line 1 tumor cells (WT-Line 1) and their non-malignant counterparts transduced with a dominant negative inhibitor of NFkappaB (mIkappaB-Line 1), we observed upregulated retinoic acid receptors (RARs) and the cAMP response element modulator (CREM), in mIkappaB-Line 1 tumor cells, and utilized heterologous promoter-reporter constructs to confirm enhanced responsiveness. We translate these findings by inducing retinoid and cAMP transcriptional programs in WT-Line 1 tumor cells with pharmacologic doses of all-trans retinoic acid (at-RA) and pentoxyfilline (PTX), respectively, and demonstrate suppression of NFkappaB activity, tumor cell derived matrix metalloprotease 9 activity, tumor cell invasiveness in vitro and spontaneous metastasis in vivo. Our results are consistent with the putative role of retinoids and cAMP in the malignant reversion of tumor cells and illustrative of the binary nature of transcriptional programs that modulate malignant progression.

Malignant reversion of a human osteosarcoma cell line, Saos-2, by inhibition of NFkappaB.

Beyond a pivotal role in neoplastic transformation and malignant progression, NFkappaB is intricately involved in bone biology, pointed up by the osteopetrotic phenotype of NFkappaB (p50-p52) double knock-out mice. Osteopetrosis results from intrinsic defects in osteoclastogenesis, loss of osteoclast bone resorptive activity and, questionably, increased osteoblast activity (bone matrix apposition and mineralization). We here report that inhibition of NFkappaB signaling activity in Saos-2 cells results in a marked decrease in cellular proliferation, assessed by the incorporation of radioactive thymidine into cellular DNA. Decreased cellular proliferation was accompanied by the induction of bone morphogenic proteins (BMP) 4, 7, and the osteoblast specific transciption factor, Cbfa1, heralding osteoblast differentiation, given the induction of alkaline phosphatase, osteopontin, and osteocalcin message levels and the attendant increase in matrix deposition and mineralization in vitro. These results point to the negative regulation of osteoblast differentiation by NFkappaB, with implications in the pathogenesis and progression of osteosarcomas.

Synergism of aminobisphosphonates and farnesyl transferase inhibitors on tumor metastasis.

Aminobisphosphonates have shown significant antitumor activity in vitro and in vivo with selective pharmacodistribution to bone, and an established role in the treatment of malignant bone disease. Given that the mode of action of aminobisphosphonates involves decreasing the prenylation of the Rho family of proteins, through decreasing the availability of prenyl groups (farnesyl and geranylgeranyl isoprenoids), the authors sought the inhibition of Rho protein prenylation at two points, by using an aminobiphosphonate (alendronate) in conjunction with a prenyl transferase inhibitor (R115777, a specific farnesyl transferase inhibitor with limited effects in geranylgeranyl transferase). The authors show synergistic inhibition of the prenylation dependent membrane association and migratory function of Rho proteins, translating into a suppressive effect on in vitro tumor cell invasiveness and in vivo metastasis. The findings support the use of aminobisphosphonates in conjunction with farnesyl transferase inhibitors in the prevention of metastatic progression and suggest that metastatic progression is a valid end point in assessing the antitumor activity of farnesyl transferase inhibitors.