Faculty perceptions of factors that indicate successful educational outcomes of medical students' research projects: a focus group study.

BACKGROUND: A growing number of medical schools have individual scholarly projects as a component of their curricula. The fact that all students, and not only those with research interests, have to carry out a project puts high demands on the projects and their supervision. Evidence is lacking for how to produce scholarly projects with satisfactory outcomes. This study aimed to explore the observations of faculty teachers regarding factors that predict the educational outcomes of medical students' scholarly projects. METHODS: Two focus group interviews were held with seven of the 16 faculty coordinators who were external reviewers of students' research projects. The audio-recorded interview transcripts were analyzed using qualitative content analysis. We employed a constant comparative approach to create categories firmly grounded in the participants' experiences. A successful project was defined as coordinators' perception that the stated learning outcomes were achieved, in terms of students' ability to demonstrate a scientific attitude. RESULTS: Five categories emerged from the data: Supervision, Project setup, Student characteristics, Curriculum structure, and Institutional guidance. The supervisors' experience and availability to students were mentioned as key factors for successful outcomes. Further, a clear aim and adaptation to the time frame were stated to be project-related factors that were also supervisors' responsibilities. Important student-related factors were skills related to scientific writing, taking ownership of and managing the projects, and making use of feedback. Finally, the course requirements, support, and control accomplished by faculty coordinators played important roles. CONCLUSIONS: Contributing factors to achievement of the learning outcomes were supervisors' commitment and experience, and the projects being suitable for the time frame and having a clearly stated research question. Furthermore, the students' prowess at scientific writing, adequate handling of feedback, and ability to assume ownership of the project contributed to the final outcome, as did adherence to curricular instructions.

Does reality meet expectations? An analysis of medical students' expectations and perceived learning during mandatory research projects.

BACKGROUND: Although much has been written about structure and outcomes of medical students' curricular research projects, less attention has been paid to the expectations on such projects. In order to foster students' scientific understanding and improve the quality of mandatory research projects, we compared students' pre-course expectations with their post-course insights regarding learning and transferable skills. METHODS: A prospective cross-sectional questionnaire study. All students registered on a mandatory 20-week research project course in 2011-2013 were e-mailed questionnaires in the beginning and after the course asking them to rate statements on expectations and perceived learning on a 5-point Likert scale. Of 652 students, 358 (mean age 26 years; range 21-49; 63% females) returned both questionnaires, corresponding to a response rate of 55%. RESULTS: The ratings for expectations as well as perceived learning were highest for learning to search and critically appraise literature. The greatest pre- and post-course differences were indicated for participation in scientific discussions and oral communication. Surprisingly, both pre- and post-course ratings were low for research ethics. The highest post-course ratings regarding skills for future working life were given to items pertaining to understanding the scientific basis of medicine, ability to follow the development of knowledge and to critically integrate knowledge. Female students had higher expectations than male students. Those with a previous university degree had lower ratings of expectations and perceived learning. Students with basic science projects reported higher expectations and higher learning compared to students with other projects. Previous research experience had no significant influence on expectations nor learning. The correlations between post-course ratings of learning and skills showed that problem-solving ability had a relatively high correlation with all skills. CONCLUSIONS: Students had high expectations and perceived the course improved crucial practical skills. However, expectations were not quite met regarding aspects of scientific communication, and hypothesis formulation, likely because these require more extensive practice and feedback. Students should be actively involved in ethical discussions and oral communication should be trained repeatedly as it is an important task of doctors to communicate scientific information to patients and non-experts.

A Shifty Target: Tumor-Initiating Cells and Their Metabolism.

Tumor-initiating cells (TICs), or cancer stem cells, constitute highly chemoresistant, asymmetrically dividing, and tumor-initiating populations in cancer and are thought to play a key role in metastatic and chemoresistant disease. Tumor-initiating cells are isolated from cell lines and clinical samples based on features such as sphere formation in stem cell medium and expression of TIC markers, typically a set of outer membrane proteins and certain transcription factors. Although both bulk tumor cells and TICs show an adaptive metabolic plasticity, TIC metabolism is thought to differ and likely in a tumor-specific and growth condition-dependent pattern. In the context of some common solid tumor diseases, we here review reports on how TIC isolation methods and markers associate with metabolic features, with some focus on oxidative metabolism, including fatty acid and lipid metabolism. These have emerged as significant factors in TIC phenotypes, and in tumor biology as a whole. Other sections address mitochondrial biogenesis and dynamics in TICs, and the influence of the tumor microenvironment. Further elucidation of the complex biology of TICs and their metabolism will require advanced methodologies.

On mitochondrial metabolism in tumor biology.

PURPOSE OF REVIEW: To provide examples of mitochondria-specific metabolic events that influence tumor cell biology, and of metabolism-related mitochondrial biomarkers and therapeutic targets in cancer cells. RECENT FINDINGS: Cancer cell mitochondria are rewired to optimally serve the cancer cell under various conditions of cellular stress. The nonexhaustive list of mitochondrial alterations that support cancer cell proliferation, survival, and/or progression includes upregulation of oxidative metabolism and use of alternative substrates, oncometabolites, increased superoxide production, mutated mitochondrial DNA, and altered mitochondrial morphology and dynamics. Potential therapeutic targets include fatty acid oxidation, voltage-dependent anion channel-1, the pyruvate dehydrogenase complex, and Complex I. SUMMARY: Some phenotypical traits, for example, chemoresistance and metastasis, are likely regulated by a fine-tuned balance between several metabolic processes and events that are upregulated in parallel and are also dependent on microenvironmental cues. Many metabolism-related mitochondrial biomarkers show prognostic value, but the biological interpretation of the data may be confounded by the overall metabolic status and context. Understanding metabolic regulation of stemness is important for targeting cancer stem cells. Therapeutic targeting of cancer cell mitochondria remains experimental but promising, and more predictive markers will be needed for metabolism-based treatments and personalized medicine.

Medical students' research productivity and career preferences; a 2-year prospective follow-up study.

BACKGROUND: Linking undergraduate medical education to scientific research is necessary for the quality of future health care, and students´ individual research projects are one way to do so. Assessment of the impact of such projects is of interest for both educational and research-oriented segments of medical schools. Here, we examined the scholarly products and medical students' career preferences 2 years after a mandatory research project course. METHODS: A prospective cross-sectional questionnaire study. All 581 students registered on a 20-week research project course between September 2010 through September 2012 were e-mailed a questionnaire 2 years after completing the course. RESULTS: In total, 392 students (mean age 27 years; 60% females) responded (67% response rate). 59 students (15%) were co-authors on a scientific paper published in an international journal, 6 students had published in a national journal, and 57 students had co-authored a paper submitted for publication. Totally, 122 scientific papers had been submitted. Moreover, 67 (17%) students had given 107 oral or poster presentations nationally or internationally during the follow-up. Career-wise, 36 students (9%) had been registered as PhD students and an additional 127 students (34%) were planning to register. Those who did not plan doctoral studies were significantly older (p = 0.013) than those who did. However, 35% reported that they would in the coming 5 years prefer to work as clinicians only, and this group was significantly younger than those who envisaged participation in research. There were no significant gender differences. CONCLUSIONS: Approximately a third of the students had authored papers and/or public presentations, and a similar fraction had career plans involving a PhD degree. The results indicate that the project course had a positive impact on continued supervisor-student collaboration on a professional level, but also that strategies to encourage young doctors to perform clinical research may be needed.

Metabolic markers and HSP60 in chemonaive serous solid ovarian cancer versus ascites.

OBJECTIVE: Metabolic pathway alterations in cancer are thought to be dependent upon tumor type-specific oncogenic activation and local nutrient and oxygen supply during disease progression. In serous ovarian cancer, the typical peritoneal spread of disease is caused by shedding of tumor cells into the abdominal cavity, often along with ascites formation. Not much is known about the metabolic features of these detached serous tumor cells. In this study, we investigate the messenger RNA (mRNA) expression of GAPDH (glycolytic glyceraldehyde 3-phosphate dehydrogenase) and PKM2 (pyruvate kinase isoform M2), ATP5B (mitochondrial ß-F1-ATPase), and heat shock protein 60 in matched serous solid tumor and corresponding ascites. MATERIALS/METHODS: Fresh samples from solid tumor and corresponding ascites were prospectively collected from 40 patients undergoing primary surgery for suspected advanced ovarian cancer. Of these, 25 met the study eligibility criteria, that is, stage IIC to IV disease of the serous (24) or endometrioid (1) subtype with solid and ascites specimens containing 50% or more tumor cells and with good quality and quantity mRNA yield. All but 2 patients (92%) had type II disease. GAPDH, PKM2, ATP5B, and HSP60 mRNA expressions were assessed by real-time polymerase chain reaction. For each marker, the mRNA expression in solid tumor was pairwise compared with the corresponding expression in ascites using the Wilcoxon matched pairs signed rank sum test. RESULTS: In contrast to our hypothesis, the mRNA expression of analyzed metabolic markers and HSP60 did not significantly differ between matched solid tumor and malignant ascites. CONCLUSIONS: Our results indicate that further expression changes in genes related to glycolysis or oxidative phosphorylation are not a prerequisite for serous cancer cell survival after detachment.

HSP60 predicts survival in advanced serous ovarian cancer.

OBJECTIVE: Heat shock protein 60 (HSP60) plays an essential role in malignant cell survival. We evaluated the prognostic and treatment predictive value of HSP60 in advanced ovarian cancer. METHODS: Fresh tumor samples were prospectively collected from 123 patients undergoing primary surgery for suspected advanced ovarian cancer. Of these, 57 fulfilled the eligibility criteria, that is, International Federation of Gynecology and Obstetrics stage IIC-IV, serous/endometrioid tumors, platinum-based chemotherapy, and specimens with 50% tumor cells or greater. Heat shock protein 60 mRNA and protein expression was determined by real-time polymerase chain reaction and immunohistochemistry. We estimated the association between HSP60 and overall survival (OS) and platinum-free interval (PFI) by Cox proportional hazards models and its relationship with treatment response by Fisher's exact test. Median follow-up was 60 months. RESULTS: High HSP60 mRNA expression was associated with shorter OS (hazard ratio [HR], 3.4; 95% confidence interval [CI], 1.3-8.5) and PFI (HR, 3.3; 95% CI, 1.5-7.2). Likewise, high HSP60 protein expression was associated with shorter OS (HR, 3.2; 95% CI, 1.5-7.1) and PFI (HR, 2.6; 95% CI, 1.3-5.3). Median survival for patients with high HSP60 protein expression was 31 months compared with 55 months for low expression cases (P = 0.016). The impact on OS and PFI was even stronger in the subgroup of grade 3 serous tumors. All patients with low HSP60 levels responded to first-line chemotherapy. CONCLUSION: Heat shock protein 60 may identify groups of advanced serous ovarian cancer with different prognosis and treatment response.

Metabolic markers GAPDH, PKM2, ATP5B and BEC-index in advanced serous ovarian cancer.

BACKGROUND: A deregulated energy metabolism is a hallmark of malignant disease that offers possible future targets for treatment. We investigated the prognostic value of the glycolytic enzymes glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and pyruvate kinase type M2 (PKM2), mitochondrial ß-F1-ATPase (ATP5B) and the bioenergetic cellular (BEC) index in advanced ovarian cancer. METHODS: Fresh tumor samples were prospectively collected from 123 patients undergoing primary surgery for suspected advanced ovarian cancer. Of these, 57 met the eligibility criteria; stage IIC-IV, serous or endometrioid subtype, specimens containing ≥ 50% tumor cells and patients receiving platinum-based chemotherapy. An adequate amount of mRNA could be extracted in all but one case, with a resultant study population of 56 patients. Eighty-six percent of cases had serous tumors, and 93% were grade 2-3. GAPDH, PKM2 and ATP5B mRNA- and protein expression was assessed by real-time PCR and immunohistochemistry. We estimated the association with platinum-free interval (PFI) and overall survival (OS) by Cox proportional hazards models. Median follow-up was 60 months. RESULTS: High GAPDH mRNA levels (HR 2.1, 95% CI 1.0-4.5) and low BEC-index (HR 0.47, 95% CI 0.23-0.95) were both independently associated with shorter PFI. Median PFI for patients with high GAPDH mRNA was 5.0 months compared to 10.1 months for low expression cases (p = 0.031). Similarly, median PFI for patients with low BEC-index based on mRNA was 5.3 months compared to 9.8 months for high BEC-index cases (p = 0.028). CONCLUSIONS: High GAPDH or low BEC-index mRNA expression indicate early disease progression in advanced serous ovarian cancer.

3-Bromopyruvate: targets and outcomes.

The pyruvate mimetic 3-bromopyruvate (3-BP) is generally presented as an inhibitor of glycolysis and has shown remarkable efficacy in not only preventing tumor growth, but even eradicating existant tumors in animal studies. We here review reported molecular targets of 3-BP and suggest that the very range of possible targets, which pertain to the altered energy metabolism of tumor cells, contributes both to the efficacy and the tumor specificity of the drug. Its in vivo efficacy is suggested to be due to a combination of glycolytic and mitochondrial targets, as well as to secondary effects affecting the tumor microenvironment. The cytotoxicity of 3-BP is less due to pyruvate mimicry than to alkylation of, e.g., key thiols. Alkylation of DNA/RNA has not been reported. More research is warranted to better understand the pharmacokinetics of 3-BP, and its potential toxic effects to normal cells, in particular those that are highly ATP-/mitochondrion-dependent.

Protein markers of cancer-associated fibroblasts and tumor-initiating cells reveal subpopulations in freshly isolated ovarian cancer ascites.

BACKGROUND: In ovarian cancer, massive intraperitoneal dissemination is due to exfoliated tumor cells in ascites. Tumor-initiating cells (TICs or cancer stem cells) and cells showing epithelial-mesenchymal-transition (EMT) are particularly implicated. Spontaneous spherical cell aggregates are sometimes observed, but although similar to those formed by TICs in vitro, their significance is unclear. METHODS: Cells freshly isolated from malignant ascites were separated into sphere samples (S-type samples, n=9) and monolayer-forming single-cell suspensions (M-type, n=18). Using western blot, these were then compared for expression of protein markers of EMT, TIC, and of cancer-associated fibroblasts (CAFs). RESULTS: S-type cells differed significantly from M-type by expressing high levels of E-cadherin and no or little vimentin, integrin-ß3 or stem cell transcription factor Oct-4A. By contrast, M-type samples were enriched for CD44, Oct-4A and for CAF markers. Independently of M- and S-type, there was a strong correlation between TIC markers Nanog and EpCAM. The CAF marker α-SMA correlated with clinical stage IV. This is the first report on CAF markers in malignant ascites and on SUMOylation of Oct-4A in ovarian cancer. CONCLUSIONS: In addition to demonstrating potentially high levels of TICs in ascites, the results suggest that the S-type population is the less tumorigenic one. Nanog(high)/EpCAM(high) samples represent a TIC subset which may be either M- or S-type, and which is separate from the CD44(high)/Oct-4A(high) subset observed only in M-type samples. This demonstrates a heterogeneity in TIC populations in vivo which has practical implications for TIC isolation based on cell sorting. The biological heterogeneity will need to be addressed in future therapeutical strategies.

PGC1α and VDAC1 expression in endometrial cancer.

Endometrial cancer (EC) is one of the ten most common gynecological cancers. As in most cancers, EC tumour progression involves alterations in cellular metabolism and can be associated with, for instance, altered levels of glycolytic enzymes. Mitochondrial functions and proteins are known to serve key roles in tumour metabolism and progression. The transcriptional coactivator peroxisome proliferator-activated receptor gamma coactivator 1 (PGC1α) is a major regulator of mitochondrial biogenesis and function, albeit of varying prognostic value in different cancers. The voltage-dependent anion channel type 1 (VDAC1) regulates apoptosis as well as metabolite import and export over the mitochondrial outer membrane, and is often used for comparative quantification of mitochondrial content. Using immunohistochemistry, the present study examined protein expression levels of PGC1α and VDAC1 in tumour and paired benign tissue samples from 148 patients with EC, in order to examine associations with clinical data, such as stage and grade, Ki-67, p53 status, clinical resistance and overall survival. The expression levels of both PGC1α and VDAC1, as well as a PGC1α downstream effector, were significantly lower in tumor tissues than in benign tissues, suggesting altered mitochondrial function in EC. However, Kaplan-Meier, log rank and Spearman's rank correlation tests revealed that their expression was not correlated with survival and clinical data. Therefore, PGC1α and VDAC1 are not of major prognostic value in EC.

Arsenic trioxide is highly cytotoxic to small cell lung carcinoma cells.

Small cell lung carcinoma (SCLC) is an extremely aggressive form of cancer and current treatment protocols are insufficient. SCLC have neuroendocrine characteristics and show phenotypical similarities to the childhood tumor neuroblastoma. As multidrug-resistant neuroblastoma cells are highly sensitive to arsenic trioxide (As2O3) in vitro and in vivo, we here studied the cytotoxic effects of As2O3 on SCLC cells. As2O3 induced pronounced cell death in SCLC cells at clinically relevant concentrations, and also at hypoxia. SCLC cells were more sensitive than non-SCLC cells to As2O3. Cell death was mainly due to necrosis, although apoptotic responses were also seen. A significant in vivo effect of As2O3 on SCLC growth was shown in a nude mice-xenograft model, although a fraction of the treated tumor-bearing animals did not respond. The nonresponding SCLC tumors differed in morphology and cell organization compared with treatment-responsive tumors, which in turn, showed decreased vascularization and higher expression of neuroendocrine markers compared with control tumors. Our results suggest a potential clinical application of As2O3 in SCLC therapy. In addition to cell death induction, antiangiogenic induction of differentiation may also be part of the in vivo effect of As2O3 on SCLC growth, as suggested by an increase in neuroendocrine markers in cultured cells.

Cisplatin overcomes Bcl-2-mediated resistance to apoptosis via preferential engagement of Bak: critical role of Noxa-mediated lipid peroxidation.

Increased expression of antiapoptotic Bcl-2 proteins confers therapeutic resistance in various cancer types. Targeting Bcl-2 proteins by small molecules or activating alternative pathways to bypass Bcl-2-mediated protection to promote apoptosis are two approaches to overcoming therapeutic resistance. Here, we show that cisplatin triggers a Bak-dependent pathway to induce apoptosis in Bcl-2-overexpressing MCF-7 cells. p53-mediated induction of Noxa expression, generation of lipid peroxidation end products and induction of Noxa-Mcl-1 interaction are necessary for this pathway to function. Although Puma is also induced by cisplatin treatment, it is not required for apoptosis. Similarly, reactive oxygen species production by cisplatin did not have any effect on cisplatin-induced apoptosis in MCF-7 Bcl-2 cells. Furthermore, p53 promotes cisplatin-induced apoptosis by directly binding and counteracting Bcl-x(L) antiapoptotic function. In conclusion, our findings suggest a novel mode of action for cisplatin to overcome Bcl-2-mediated protection against apoptosis, which requires preferential activation of Bak and p53-mediated upregulation of Noxa protein levels and lipid peroxidation.

Restriction of cisplatin induction of acute apoptosis to a subpopulation of cells in a three-dimensional carcinoma culture model.

Cisplatin is a clinically important chemotherapeutical agent used to treat epithelial malignancies. High concentrations (20-100 microM) of cisplatin have been used in numerous studies to induce apoptosis of carcinoma cells grown in monolayer culture over 24-48 hr. These conditions may not be relevant to 3-D tumor tissue in vivo and the importance of apoptosis for tumor response is controversial. We here studied the effects of cisplatin on a 3-D colon carcinoma in vitro model (multicellular spheroids). Cisplatin at a dose of 40 microM induced active caspase-3 preferentially in the peripheral 30 microm cell layer of spheroids, mainly during late stages (72-96 hr). The p53 response to cisplatin was also largely confined to peripheral cell layers. Despite the use of a high cisplatin concentration, a significant fraction of the cells in the spheroids survived treatment. A high proportion of surviving cells stained positive for beta-galactosidase, a marker of premature senescence. Cells growth-arrested by cisplatin treatment showed a higher spontaneous cell death rate than untreated proliferating cells. We propose that acute apoptosis is of minor significance for the overall response of carcinoma cells to cisplatin treatment.

Potentiation of chemotherapeutic drugs by energy metabolism inhibitors 2-deoxyglucose and etomoxir.

Inhibition of energy production as a strategy for potentiation of anticancer chemotherapy was investigated using 1 glycolysis inhibitor and 1 fatty acid beta-oxidation inhibitor-2-deoxyglucose and etomoxir, respectively, both known to be clinically well tolerated. Eighteen anticancer drugs were screened for potentiation by these inhibitors. 2-deoxyglucose potentiated acute apoptosis (24 hr) induced mainly by some, but not all, genotoxic drugs, whereas etomoxir had effect only on cisplatin. By contrast, etomoxir did potentiate the overall, 48 hr effects of some genotoxic drugs, and was in addition more efficient than deoxyglucose in potentiating the overall effects of several non-genotoxic drugs. Both types of potentiation were largely lost in the absence of p53. Because cisplatin was potentiated by both energy inhibitors in both types of assay, it was investigated at additional concentrations and over longer time. Both energy inhibitors strongly potentiated non-apoptotic concentrations of cisplatin in p53-wildtype as well as in p53-deficient, cisplatin-resistant HCT-116 colon carcinoma cells. Reduced ATP levels correlated with, but were not sole determinants, the antiproliferative effects. We conclude that the long-term effects of cisplatin potentiation are important and either p53-independent or improved by a lack of p53. We also conclude that although the potentiated drugs as yet have no obvious mechanistic factor in common, the strategy holds promise with genotoxic as well non-genotoxic anticancer drugs.

Cytokeratin-18 is a useful serum biomarker for early determination of response of breast carcinomas to chemotherapy.

PURPOSE: With a widening arsenal of cancer therapies available, it is important to develop therapy-specific predictive markers and methods to rapidly assess treatment efficacy. We here evaluated the use of cytokeratin-18 (CK18) as a serum biomarker for monitoring chemotherapy-induced cell death in breast cancer. EXPERIMENTAL DESIGN: Different molecular forms of CK18 (caspase cleaved and total) were assessed by specific ELISA assays. Drug-induced release of CK18 was examined from breast carcinoma cells and tissue. CK18 protein composition was examined in serum. CK18 levels were determined in serum from 61 breast cancer patients during docetaxel or cyclophosphamide/epirubicin/5-fluorouracil (CEF) therapy. RESULTS: Caspase-cleaved CK18 molecules were released from monolayer cultures and tumor organ cultures to the extracellular compartment. CK18 was present in complexes with other cytokeratins in serum. Such CK18 protein complexes are remarkably stable, leading to favorable performance of CK18 biomarker assays for clinical investigations. Docetaxel induced increased levels of caspase-cleaved CK18 in serum from breast cancer patients, indicating apoptosis. CEF therapy led to increases predominantly in uncleaved CK18, indicating induction of necrotic cell death in many tumors. The increase in total CK18 at 24 h of the first treatment cycle correlated to the clinical response to CEF therapy (P < 0.0001). CONCLUSIONS: Induction of necrotic cell death may explain the clinical efficacy of anthracycline-based therapy for breast carcinomas with defective apoptosis pathways. We suggest that CK18 biomarkers are useful for early prediction of the response to CEF therapy in breast cancer and may be useful biomarkers for clinical trials.

Doxorubicin requires the sequential activation of caspase-2, protein kinase Cdelta, and c-Jun NH2-terminal kinase to induce apoptosis.

Here, we identified caspase-2, protein kinase C (PKC)delta, and c-Jun NH2-terminal kinase (JNK) as key components of the doxorubicin-induced apoptotic cascade. Using cells stably transfected with an antisense construct for caspase-2 (AS2) as well as a chemical caspase-2 inhibitor, we demonstrate that caspase-2 is required in doxorubicin-induced apoptosis. We also identified PKCdelta as a novel caspase-2 substrate. PKCdelta was cleaved/activated in a caspase-2-dependent manner after doxorubicin treatment both in cells and in vitro. PKCdelta is furthermore required for efficient doxorubicin-induced apoptosis because its chemical inhibition as well as adenoviral expression of a kinase dead (KD) mutant of PKCdelta severely attenuated doxorubicin-induced apoptosis. Furthermore, PKCdelta and JNK inhibition show that PKCdelta lies upstream of JNK in doxorubicin-induced death. Jnk-deficient mouse embryo fibroblasts (MEFs) were highly resistant to doxorubicin compared with wild type (WT), as were WT Jurkat cells treated with SP600125, further supporting the importance of JNK in doxorubicin-induced apoptosis. Chemical inhibitors for PKCdelta and JNK do not synergize and do not function in doxorubicin-treated AS2 cells. Caspase-2, PKCdelta, and JNK were furthermore implicated in doxorubicin-induced apoptosis of primary acute lymphoblastic leukemia blasts. The data thus support a sequential model involving caspase-2, PKCdelta, and JNK signaling in response to doxorubicin, leading to the activation of Bak and execution of apoptosis.

Target specificity and off-target effects as determinants of cancer drug efficacy.

Targeted therapeutics are aimed to hit one or a few key cellular targets. Agents that target single signaling molecules (such as EGFR and IGF-R1) often show limited clinical activities, at least in the major groups of solid tumors. Nevertheless, some signaling inhibitors are effective in the treatment of previously difficult-to-treat diseases such as renal carcinoma. Similarly, these drugs inhibit multiple kinases and/or may display off-target activities. Inhibition of cellular targets such as the proteasome, heat-shock protein 90, and histone deacetylase induces complex cellular effects, and agents that inhibit these targets show promising clinical activities. Clinically effective targeted agents are therefore reminiscent of conventional agents such as cisplatin and doxorubicin, which are known to have several cellular targets. It is becoming increasingly clear that a comprehensive understanding of the spectrum of effects exerted by an anticancer agent is fundamental for understanding its efficacy and toxicity profile.

PGC1α: Friend or Foe in Cancer?

The PGC1 family (Peroxisome proliferator-activated receptor γ (PPARγ) coactivators) of transcriptional coactivators are considered master regulators of mitochondrial biogenesis and function. The PGC1α isoform is expressed especially in metabolically active tissues, such as the liver, kidneys and brain, and responds to energy-demanding situations. Given the altered and highly adaptable metabolism of tumor cells, it is of interest to investigate PGC1α in cancer. Both high and low levels of PGC1α expression have been reported to be associated with cancer and worse prognosis, and PGC1α has been attributed with oncogenic as well as tumor suppressive features. Early in carcinogenesis PGC1α may be downregulated due to a protective anticancer role, and low levels likely reflect a glycolytic phenotype. We suggest mechanisms of PGC1α downregulation and how these might be connected to the increased cancer risk that obesity is now known to entail. Later in tumor progression PGC1α is often upregulated and is reported to contribute to increased lipid and fatty acid metabolism and/or a tumor cell phenotype with an overall metabolic plasticity that likely supports drug resistance as well as metastasis. We conclude that in cancer PGC1α is neither friend nor foe, but rather the obedient servant reacting to metabolic and environmental cues to benefit the tumor cell.

Mechanisms of action of DNA-damaging anticancer drugs in treatment of carcinomas: is acute apoptosis an "off-target" effect?

DNA damage induces apoptosis of cells of hematological origin. Apoptosis is also widely believed to be the major antiproliferative mechanism of DNA damaging anticancer drugs in other cell types, and a large number of laboratories have studied drug-induced acute apoptosis (within 24 hours) of carcinoma cells. It is, however, often overlooked that induction of apoptosis of carcinoma cells generally requires drug concentrations that are at least one order of magnitude higher than those required for loss of clonogenicity. This is true for different DNA damaging drugs such as cisplatin, doxorubicin and camptothecin. We here discuss apoptosis induction by DNA damaging agents using cisplatin as an example. Recent studies have shown that cisplatin induces caspase activation in enucleated cells (cytoplasts lacking a cell nucleus). Cisplatin-induced apoptosis in both cells and cytoplasts is associated with rapid induction of cellular reactive oxygen species and increases in [Ca(2+)](i). Cisplatin has also been reported to induce clustering of Fas/CD95 in the plasma membrane. Available data suggest that the primary responses to cisplatin-induced DNA damage are induction of long-term growth arrest ("premature cell senescence") and mitotic catastrophe, whereas acute apoptosis may be due to "off-target effects" not necessarily involving DNA damage.