The role of artificial intelligence in knowledge management for medical students and doctors.

The skill of knowledge management empowers practitioners to efficiently integrate and apply knowledge in the clinical context. Current medical knowledge is vast which is beyond the human capacity to retain. Hence, modern-day learning is not just knowledge acquisition, but the organization of knowledge in a retrievable manner. Advancing technology in digital learning spaces and artificial intelligence enables the development of personalized knowledge platforms. Clinicians should find their own ideal spaces for knowledge management from the early stages of their careers, and develop it into a lifelong learning platform, which will eventually lead to better patient care.

A professionalism program in medical education and training - From broad values to specific applications: YLL School of Medicine, Singapore.

The process for introducing and developing a program for teaching medical professionalism at the National University of Singapore, School of Medicine is outlined. Professionalism was recognised as embracing 'honesty and integrity,' 'responsibility and participation,' 'respect and sensitivity,' and 'compassion and empathy.' Those broad values are expressed as specific attitudes and behaviours that are taught and assessed throughout the course. Honesty and integrity, for example, are demonstrated by 'presenting original, authentic assignments' (in medical education); and 'accepting personal mistakes and honestly acknowledging them' (in clinical training and practice). Values and items of behaviour were drawn from the literature, and reviewed and refined to address needs identified within the Medical School. A broad spectrum of pre-clinical and clinical teachers contributed to this development. The program was reassessed to determine the extent to which it has been implemented and has evolved following its adoption. The results are confirming in that: the majority of recommendations have been implemented; the program has developed further; and is supported by ancillary student enrichment activities. Medical professionalism has been given prominence through all phases of the course. Nevertheless, challenges remain and particularly in the extent to which medical professionalism is taught and assessed in various clinical postings.

Histone deacetylases up-regulate C/EBPα expression through reduction of miR-124-3p and miR-25 in hepatocellular carcinoma.

BACKGROUND: CCAAT enhancer binding protein α (C/EBPα), as an important transcription factor involved in cell proliferation, differentiation and metabolism, was up-regulated in primary hepatocellular carcinoma (HCC) and predicted poorer prognosis. In this study, we explored how histone deacetylases (HDACs) up-regulated C/EBPα in HCC. METHODS: The protein expressions of HDAC1, HDAC2 were associated with C/EBPα by immunohistochemistry staining in a HCC tissue microarray. HCC cells were then treated with HDAC inhibitors or siRNAs to determine the roles of miR-124-3p and miR-25 in the regulation of C/EBPα mRNA expression. RESULTS: Both HDAC1 and HDAC2 proteins were significantly associated with C/EBPα. Inhibition of HDAC by either pharmacological inhibitors or siRNAs decreased C/EBPα mRNA expression in dose-dependent manners in HCC cells. HDAC inhibitors reduced C/EBPα mRNA stability as shown by pmiRGLO luciferase reporter assays. HDAC inhibition consistently induced miR-124-3p and miR-25 expression. Conversely, blockage of miR-124-3p and/or miR-25 by treatment with specific synthetic inhibitors abolished C/EBPα reduction. More importantly, C/EBPα mRNA stability could be rescued by site-directed mutations of miR-124-3p or miR-25 recognition sites in the C/EBPα 3'UTR sequence. In summary, HDAC may up-regulate C/EBPα expression through miR-124-3p and miR-25 in HCC.

CCAAT/enhancer binding protein α predicts poorer prognosis and prevents energy starvation-induced cell death in hepatocellular carcinoma.

UNLABELLED: CCAAT enhancer binding protein α (C/EBPα) plays an essential role in cellular differentiation, growth, and energy metabolism. Here, we investigate the correlation between C/EBPα and hepatocellular carcinoma (HCC) patient outcomes and how C/EBPα protects cells against energy starvation. Expression of C/EBPα protein was increased in the majority of HCCs examined (191 pairs) compared with adjacent nontumor liver tissues in HCC tissue microarrays. Its upregulation was correlated significantly with poorer overall patient survival in both Kaplan-Meier survival (P=0.017) and multivariate Cox regression (P=0.028) analyses. Stable C/EBPα-silenced cells failed to establish xenograft tumors in nude mice due to extensive necrosis, consistent with increased necrosis in human C/EBPα-deficient HCC nodules. Expression of C/EBPα protected HCC cells in vitro from glucose and glutamine starvation-induced cell death through autophagy-involved lipid catabolism. Firstly, C/EBPα promoted lipid catabolism during starvation, while inhibition of fatty acid beta-oxidation significantly sensitized cell death. Secondly, autophagy was activated in C/EBPα-expressing cells, and the inhibition of autophagy by ATG7 knockdown or chloroquine treatment attenuated lipid catabolism and subsequently sensitized cell death. Finally, we identified TMEM166 as a key player in C/EBPα-mediated autophagy induction and protection against starvation. CONCLUSION: The C/EBPα gene is important in that it links HCC carcinogenesis to autophagy-mediated lipid metabolism and resistance to energy starvation; its expression in HCC predicts poorer patient prognosis.

Medical education in Singapore.

Allopathic medical education in Singapore extends for more than a century from its simple beginnings. In recent times, changes have been rapid, both in undergraduate and postgraduate specialty medical training. Over the last decade, undergraduate medical education has increased from a single to three medical schools and the postgraduate training has expanded further by incorporating the Accreditation Council for Graduate Medical Education International framework. With these changes, the curricula, assessment systems, as well as teaching and learning approaches, with the use of technology-enhanced learning and program evaluation processes have expanded, largely based on best evidence medical education. To support these initiatives and the recent rapid expansion, most training institutions have incorporated faculty development programs, such as the Centre for Medical Education at the National University of Singapore.

Comparison of virtual patient simulation with mannequin-based simulation for improving clinical performances in assessing and managing clinical deterioration: randomized controlled trial.

BACKGROUND: Virtual patient simulation has grown substantially in health care education. A virtual patient simulation was developed as a refresher training course to reinforce nursing clinical performance in assessing and managing deteriorating patients. OBJECTIVE: The objective of this study was to describe the development of the virtual patient simulation and evaluate its efficacy, by comparing with a conventional mannequin-based simulation, for improving the nursing students' performances in assessing and managing patients with clinical deterioration. METHODS: A randomized controlled study was conducted with 57 third-year nursing students who were recruited through email. After a baseline evaluation of all participants' clinical performance in a simulated environment, the experimental group received a 2-hour fully automated virtual patient simulation while the control group received 2-hour facilitator-led mannequin-based simulation training. All participants were then re-tested one day (first posttest) and 2.5 months (second posttest) after the intervention. The participants from the experimental group completed a survey to evaluate their learning experiences with the newly developed virtual patient simulation. RESULTS: Compared to their baseline scores, both experimental and control groups demonstrated significant improvements (P<.001) in first and second post-test scores. While the experimental group had significantly lower (P<.05) second post-test scores compared with the first post-test scores, no significant difference (P=.94) was found between these two scores for the control group. The scores between groups did not differ significantly over time (P=.17). The virtual patient simulation was rated positively. CONCLUSIONS: A virtual patient simulation for a refreshing training course on assessing and managing clinical deterioration was developed. Although the randomized controlled study did not show that the virtual patient simulation was superior to mannequin-based simulation, both simulations have demonstrated to be effective refresher learning strategies for improving nursing students' clinical performance. Given the greater resource requirements of mannequin-based simulation, the virtual patient simulation provides a more promising alternative learning strategy to mitigate the decay of clinical performance over time.

Encouraging an environment to nurture lifelong learning: an Asian experience.

INTRODUCTION: Within an Asian context, this study examines the effect of changing from traditional course grades to a distinction/pass/fail (D/P/F) grading system on medical student self-perceived stress levels and on student exam performance. METHODS: At the end of the 2010-2011 academic year, the Perceived Stress Scale-10 (PSS-10) was administered to the cohort of students finishing their first year of medical studies. For the academic year 2011-2012, the grading system was changed to D/P/F for the first year of medical school. The PSS-10 was also administered to the subsequent cohort of first-year medical students at the same point in the academic year as previous. Qualitative comments were collected for both cohorts. RESULTS: Stress as measured by the PSS-10 was significantly lower in the cohort that went through the year with the D/P/F grading system in place. Thematic analysis of qualitative responses showed a shift in sources of student stress away from peer-competition. There were no significant differences in overall exam performance. DISCUSSION: Within an Asian context, switching to a D/P/F grading system can alleviate stress and peer competition without compromising knowledge. This may help foster a "learning orientation" rather than an "exam orientation," and contribute to inculcating lifelong learning skills.

Proteomic analysis of colorectal cancer metastasis: stathmin-1 revealed as a player in cancer cell migration and prognostic marker.

Metastasis accounts largely for the high mortality rate of colorectal cancer (CRC) patients. In this study, we performed comparative proteome analysis of primary CRC cell lines HCT-116 and its metastatic derivative E1 using 2-D DIGE. We identified 74 differentially expressed proteins, many of which function in transcription, translation, angiogenesis signal transduction, or cytoskeletal remodeling pathways, which are indispensable cellular processes involved in the metastatic cascade. Among these proteins, stathmin-1 (STMN1) was found to be highly up-regulated in E1 as compared to HCT-116 and was thus selected for further functional studies. Our results showed that perturbations in STMN1 levels resulted in significant changes in cell migration, invasion, adhesion, and colony formation. We further showed that the differential expression of STMN1 correlated with the cells' metastatic potential in other paradigms of CRC models. Using immunohistochemistry, we also showed that STMN1 was highly expressed in colorectal primary tumors and metastatic tissues as compared to the adjacent normal colorectal tissues. Furthermore, we also showed via tissue microarray analyses of 324 CRC tissues and Kaplan-Meier survival plot that CRC patients with higher expression of STMN1 have poorer prognosis.

Recognition and suppression of transfected plasmids by protein ZNF511-PRAP1, a potential molecular barrier to transgene expression.

Nonviral vectors present considerable advantages over viral counterparts in gene transfer. However, the poor expression efficiency of the transfected genes poses a challenge for their use in gene therapy, primarily due to the inability of these vectors to overcome various barriers, including the biological barriers. Here, we report that ZNF511-PRAP1 may be involved in the recognition and inactivation of transfected plasmids. ZNF511-PRAP1 is induced by transfection of plasmid DNA and suppresses the transcription of transfected plasmids. It binds directly to the p21 promoter in transfected plasmids but not the endogenous counterpart. Similarly, ZNF511-PRAP1 suppresses the expression of the green fluorescent protein reporter gene on transiently transfected plasmids but not an integrated red fluorescence reporter gene with the same cytomegalovirus (CMV) promoter. Therefore, ZNF511-PRAP1 is able to differentiate between exogenous/nonintegrated and endogenous/integrated DNA. The suppression by ZNF511-PRAP1 is independent of DNA methylation and can be abolished by trichostatin A (TSA) treatment and knockdown of HDAC2 and/or ZNF511-PRAP1. Furthermore, ZNF511-PRAP1 interacts directly with HDAC2. Our results revealed that transfected plasmids are recognized by ZNF511-PRAP1 and suppressed by a repressor complex comprising ZNF511-PRAP1 and HDAC2 and suggest that ZNF511-PRAP1 could play a role as a potential molecular barrier in nonviral transgene expression.

Simultaneous treatment with sorafenib and glucose restriction inhibits hepatocellular carcinoma in vitro and in vivo by impairing SIAH1-mediated mitophagy.

Transarterial chemoembolization (TACE) is the first-line treatment for unresectable intermediate-stage hepatocellular carcinoma (HCC). It is of high clinical significance to explore the synergistic effect of TACE with antiangiogenic inhibitors and the molecular mechanisms involved. This study determined that glucose, but not other analyzed nutrients, offered significant protection against cell death induced by sorafenib, as indicated by glucose deprivation sensitizing cells to sorafenib-induced cell death. Next, this synergistic effect was found to be specific to sorafenib, not to lenvatinib or the chemotherapeutic drugs cisplatin and doxorubicin. Mechanistically, sorafenib-induced mitophagy, as indicated by PINK1 accumulation, increased the phospho-poly-ubiquitination modification, accelerated mitochondrial membrane protein and mitochondrial DNA degradation, and increased the amount of mitochondrion-localized mKeima-Red engulfed by lysosomes. Among several E3 ubiquitin ligases tested, SIAH1 was found to be essential for inducing mitophagy; that is, SIAH1 silencing markedly repressed mitophagy and sensitized cells to sorafenib-induced death. Notably, the combined treatment of glucose restriction and sorafenib abolished ATP generation and mitophagy, which led to a high cell death rate. Oligomycin and antimycin, inhibitors of electron transport chain complexes, mimicked the synergistic effect of sorafenib with glucose restriction to promote cell death mediated via mitophagy inhibition. Finally, inhibition of the glucose transporter by canagliflozin (a clinically available drug used for type-II diabetes) effectively synergized with sorafenib to induce HCC cell death in vitro and to inhibit xenograft tumor growth in vivo. This study demonstrates that simultaneous treatment with sorafenib and glucose restriction is an effective approach to treat HCC, suggesting a promising combination strategy such as transarterial sorafenib-embolization (TASE) for the treatment of unresectable HCC.

C/EBPalpha is up-regulated in a subset of hepatocellular carcinomas and plays a role in cell growth and proliferation.

BACKGROUND & AIMS: C/EBPalpha (cebpa) is a putative tumor suppressor. However, initial results indicated that cebpa was up-regulated in a subset of human hepatocellular carcinomas (HCCs). The regulation and function of C/EBPalpha was investigated in HCC cell lines to clarify its role in liver carcinogenesis. METHODS: The regulation of C/EBPalpha expression was studied by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), Western blotting, immunohistochemistry, methylation-specific PCR, and chromatin immunoprecipitation assays. C/EBPalpha expression was knocked-down by small interfering RNA or short hairpin RNA. Functional assays included colony formation, methylthiotetrazole, bromodeoxyuridine incorporation, and luciferase-reporter assays. RESULTS: Cebpa was up-regulated at least 2-fold in a subset (approximately 55%) of human HCCs compared with adjacent nontumor tissues. None of the up-regulated samples were positive for hepatitis C infection. The HCC cell lines Hep3B and Huh7 expressed high, PLC/PRF/5 intermediate, HepG2 and HCC-M low levels of C/EBPalpha, recapitulating the pattern of expression observed in HCCs. No mutations were detected in the CEBPA gene in HCCs and cell lines. C/EBPalpha was localized to the nucleus and functional in Hep3B and Huh7 cells; knocking-down its expression reduced target-gene expression, colony formation, and cell growth, associated with a decrease in cyclin A and CDK4 concentrations and E2F transcriptional activity. Epigenetic mechanisms including DNA methylation, and the binding of acetylated histone H3 to the CEBPA promoter-regulated cebpa expression in the HCC cells. CONCLUSIONS: C/EBPalpha is up-regulated in a subset of HCCs and has growth-promoting activities in HCC cells. Novel oncogenic mechanisms involving C/EBPalpha may be amenable to epigenetic regulation to improve treatment outcomes.

A precisely regulated gene expression cassette potently modulates metastasis and survival in multiple solid cancers.

Successful tumor development and progression involves the complex interplay of both pro- and anti-oncogenic signaling pathways. Genetic components balancing these opposing activities are likely to require tight regulation, because even subtle alterations in their expression may disrupt this balance with major consequences for various cancer-associated phenotypes. Here, we describe a cassette of cancer-specific genes exhibiting precise transcriptional control in solid tumors. Mining a database of tumor gene expression profiles from six different tissues, we identified 48 genes exhibiting highly restricted levels of gene expression variation in tumors (n = 270) compared to nonmalignant tissues (n = 71). Comprising genes linked to multiple cancer-related pathways, the restricted expression of this "Poised Gene Cassette" (PGC) was robustly validated across 11 independent cohorts of approximately 1,300 samples from multiple cancer types. In three separate experimental models, subtle alterations in PGC expression were consistently associated with significant differences in metastatic and invasive potential. We functionally confirmed this association in siRNA knockdown experiments of five PGC genes (p53CSV, MAP3K11, MTCH2, CPSF6, and SKIP), which either directly enhanced the invasive capacities or inhibited the proliferation of AGS cancer cells. In primary tumors, similar subtle alterations in PGC expression were also repeatedly associated with clinical outcome in multiple cohorts. Taken collectively, these findings support the existence of a common set of precisely controlled genes in solid tumors. Since inducing small activity changes in these genes may prove sufficient to potently influence various tumor phenotypes such as metastasis, targeting such precisely regulated genes may represent a promising avenue for novel anti-cancer therapies.

Cytoskeletal Dynamics in Epithelial-Mesenchymal Transition: Insights into Therapeutic Targets for Cancer Metastasis.

In cancer cells, a vital cellular process during metastasis is the transformation of epithelial cells towards motile mesenchymal cells called the epithelial to mesenchymal transition (EMT). The cytoskeleton is an active network of three intracellular filaments: actin cytoskeleton, microtubules, and intermediate filaments. These filaments play a central role in the structural design and cell behavior and are necessary for EMT. During EMT, epithelial cells undergo a cellular transformation as manifested by cell elongation, migration, and invasion, coordinated by actin cytoskeleton reorganization. The actin cytoskeleton is an extremely dynamic structure, controlled by a balance of assembly and disassembly of actin filaments. Actin-binding proteins regulate the process of actin polymerization and depolymerization. Microtubule reorganization also plays an important role in cell migration and polarization. Intermediate filaments are rearranged, switching to a vimentin-rich network, and this protein is used as a marker for a mesenchymal cell. Hence, targeting EMT by regulating the activities of their key components may be a potential solution to metastasis. This review summarizes the research done on the physiological functions of the cytoskeleton, its role in the EMT process, and its effect on multidrug-resistant (MDR) cancer cells-highlight some future perspectives in cancer therapy by targeting cytoskeleton.

Cytoskeletal Proteins in Cancer and Intracellular Stress: A Therapeutic Perspective.

Cytoskeletal proteins, which consist of different sub-families of proteins including microtubules, actin and intermediate filaments, are essential for survival and cellular processes in both normal as well as cancer cells. However, in cancer cells, these mechanisms can be altered to promote tumour development and progression, whereby the functions of cytoskeletal proteins are co-opted to facilitate increased migrative and invasive capabilities, proliferation, as well as resistance to cellular and environmental stresses. Herein, we discuss the cytoskeletal responses to important intracellular stresses (such as mitochondrial, endoplasmic reticulum and oxidative stresses), and delineate the consequences of these responses, including effects on oncogenic signalling. In addition, we elaborate how the cytoskeleton and its associated molecules present themselves as therapeutic targets. The potential and limitations of targeting new classes of cytoskeletal proteins are also explored, in the context of developing novel strategies that impact cancer progression.

The pro-survival function of DLEC1 and its protection of cancer cells against 5-FU-induced apoptosis through up-regulation of BCL-XL.

The tumor suppressor DLEC1 has been shown to promote cell proliferation when AP-2α2 is down-regulated in HCT116 stable clones, suggesting its pro-survival nature. However, the pro-survival function of DLEC1 has not been confirmed in other cells and its underlying mechanisms remain elusive. Therefore, we knocked down DLEC1 in a panel of cell lines and found that DLEC1 depletion caused various extents of cell death through intrinsic pathway. DLEC1 overexpression promoted cell survival and reduced cell death in cancer cells after 5-FU treatment, while DLEC1 down-regulation sensitized cancer cells to 5-FU. Further studies demonstrated that DLEC1 attenuated the increase in cleaved PARP, caspase-3 and caspase-7, the activity of caspase-9 and the diffusion of cytosolic cytochrome c from mitochondria. Our data also showed that BCL-XL was up-regulated by DLEC1 in stable clones after 5-FU treatment. Altogether, these results indicated that DLEC1 protects cells against cell death induced by 5-FU through the attenuation of active proteins in caspase cascade and the up-regulation of BCL-XL. Therefore, DLEC1 can be a pro-survival protein under certain circumstances and a potential therapeutic target for increasing sensitivity of cancer cells to 5-FU.

Fatty acid activation in carcinogenesis and cancer development: Essential roles of long-chain acyl-CoA synthetases.

The significance of fatty acid metabolism in cancer initiation and development is increasingly accepted by scientists and the public due to the high prevalence of overweight and obese individuals. Fatty acids have different turnovers in the body: Either breakdown into acetyl-CoA to aid ATP generation through catabolic metabolism or incorporation into triacylglycerol and phospholipid through anabolic metabolism. However, these two distinct pathways require a common initial step known as fatty acid activation. Long-chain acyl-CoA synthetases (ACSLs), which are responsible for activation of the most abundant long-chain fatty acids, are commonly deregulated in cancer. This deregulation is also associated with poor survival in patients with cancer. Fatty acids physiologically regulate ACSL expression, but cancer cells could hijack certain involved regulatory mechanisms to deregulate ACSLs. Among the five family isoforms, ACSL1 and ACSL4 are able to promote ungoverned cell growth, facilitate tumor invasion and evade programmed cell death, while ACSL3 may have relatively complex functions in different types of cancer. Notably, ACSL4 is also essential for the induction of ferroptosis (another form of programmed cell death) by facilitating arachidonic acid oxidation, which makes the enzyme a desirable cancer target. The present review thus evaluates the functions of deregulated ACSLs in cancer, the possible molecular mechanisms involved and the chemotherapeutic potentials to target ACSLs. A better understanding of the pathological effects of ACSLs in cancer and the involved molecular mechanisms will aid in delineating the exact role of fatty acid metabolism in cancer and designing precise cancer prevention and treatment strategies.

Improving a newly adapted teaching and learning approach: Collaborative Learning Cases using an action research.

PURPOSE: Although medical curricula are now better structured for integration of biomedical sciences and clinical training, most teaching and learning activities still follow the older teacher-centric discipline-specific formats. A newer pedagogical approach, known as Collaborative Learning Cases (CLCs), was adopted in the medical school to facilitate integration and collaborative learning. Before incorporating CLCs into the curriculum of year 1 students, two pilot runs using the action research method was carried out to improve the design of CLCs. METHODS: We employed the four-phase Kemmis and McTaggart's action research spiral in two cycles to improve the design of CLCs. A class of 300 first-year medical students (for both cycles), 11 tutors (first cycle), and 16 tutors (second cycle) were involved in this research. Data was collected using the 5-points Likert scale survey, open-ended questionnaire, and observation. RESULTS: From the data collected, we learned that more effort was required to train the tutors to understand the principles of CLCs and their role in the CLCs sessions. Although action research enables the faculty to improve the design of CLCs, finding the right technology tools to support collaboration and enhance learning during the CLCs remains a challenge. CONCLUSION: The two cycles of action research was effective in helping us design a better learning environment during the CLCs by clarifying tutors' roles, improving group and time management, and meaningful use of technology.

CCAAT/enhancer binding protein alpha knock-in mice exhibit early liver glycogen storage and reduced susceptibility to hepatocellular carcinoma.

The CCAAT/enhancer binding protein alpha (C/EBPalpha) is vital for establishing normal hepatic energy homeostasis and moderating hepatocellular growth. CEBPA loss-of-function mutations identified in acute myeloid leukemia patients support a tumor suppressor role for C/EBPalpha. Recent work showed reductions of C/EBPalpha levels in human hepatocellular carcinoma with the reductions correlating to tumor size and progression. We investigated the potential of reactivating c/ebpalpha expression during hepatic carcinogenesis to prevent tumor cell growth. We have developed a c/ebpalpha knock-in mouse in which a single-copy c/ebpalpha is regulated by one allele of the alpha-fetoprotein (AFP) gene promoter. The knock-in mice are physically indistinguishable from wild-type (WT) controls. However, knock-in animals were found to deposit fetal hepatic glycogen earlier than WT animals. Quantitative real-time PCR confirmed early c/ebpalpha expression and early glycogen synthase gene activation in knock-in fetuses. We then used diethylnitrosamine to induce hepatocellular carcinoma in our animals. Diethylnitrosamine produced half the number of hepatocellular nodules in knock-in mice as in WT mice. Immunohistochemistry showed reduced C/EBPalpha content in WT nodules whereas knock-in nodules stained strongly for C/EBPalpha. The p21 protein was examined because it mediates a C/EBPalpha growth arrest pathway. Nuclear p21 was absent in WT nodules whereas cytoplasmic p21 was abundant; knock-in nodules were positive for nuclear p21. Interestingly, only C/EBPalpha-positive nodules were positive for nuclear p21, suggesting that C/EBPalpha may be required to direct p21 to the cell nucleus to inhibit growth. Our data establish that controlled C/EBPalpha production can inhibit liver tumor growth in vivo.

Acetyl-keto-beta-boswellic acid inhibits cellular proliferation through a p21-dependent pathway in colon cancer cells.

1. Although there is increasing evidence showing that boswellic acid might be a potential anticancer agent, the mechanisms involved in its action are unclear. 2. In the present study, we showed that acetyl-keto-beta-boswellic acid (AKBA) inhibited cellular growth in several colon cancer cell lines. Cell cycle analysis by flow cytometry showed that cells were arrested at the G1 phase after AKBA treatment. 3. Further analysis showed that cyclin D1 and E, CDK 2 and 4 and phosphorylated Rb were decreased in AKBA-treated cells while p21 expression was increased. 4. The growth inhibitory effect of AKBA was dependent on p21 but not p53. HCT-116 p53(-/-) cells were sensitized to the apoptotic effect of AKBA, suggesting that p21 may have protected cells against apoptosis by inducing a G1 arrest.5. In conclusion, we have demonstrated that AKBA inhibited cellular growth in colon cancer cells. These findings may have implications to the use of boswellic acids as potential anticancer agents in colon cancer.

The proline-rich acidic protein is epigenetically regulated and inhibits growth of cancer cell lines.

The proline-rich acidic protein (PRAP) gene was found previously to be expressed in the epithelial cells of the mouse and rat gastrointestinal tracts, and pregnant mouse uterus. This article describes the isolation, distribution, and functional characterization of the human homologue. PRAP was abundantly expressed in the epithelial cells of the human liver, kidney, gastrointestinal tract, and cervix. PRAP expression was significantly down-regulated in hepatocellular carcinoma and right colon adenocarcinoma compared with the respective adjacent normal tissues. Treatment of the cells with butyrate, trichostatin A, and 5'-aza-2' deoxycytidine caused increases in PRAP gene expression of up to 30-fold, suggesting that the gene is suppressed through epigenetic mechanisms involving histone deacetylation and methylation. To determine the significance of PRAP expression in cancer cells, we cloned PRAP and its two major splice variants from human colon and liver, and overexpressed it in HeLa, HT29, and HepG2 cells. PRAP caused cell growth inhibition in the cancer cell lines in transient transfection assays, colony formation assays, and in the growth rates of stable clones. The data suggest that PRAP and its variants may play an important role in maintaining normal growth homeostasis in epithelial cells. The epigenetic suppression of PRAP expression in cancer may cause growth dysregulation, a hallmark of the carcinogenic process.