Inequalities in survival and care across social determinants of health in a cohort of advanced lung cancer patients in Quebec (Canada): A high-resolution population-level analysis.

BACKGROUND: Advanced lung cancer patients exposed to breakthrough therapies like EGFR tyrosine kinase inhibitors (EGFR-TKI) may experience social inequalities in survival, partly from differences in care. This study examined survival by neighborhood-level socioeconomic and sociodemographic status, and geographical location of advanced lung cancer patients who received gefitinib, an EGFR-TKI, as first-line palliative treatment. Differences in the use and delay of EGFR-TKI treatment were also examined. METHODS: Lung cancer patients receiving gefitinib from 2001 to 2019 were identified from Quebec's health administrative databases. Accounting for age and sex, estimates were obtained for the median survival time from treatment to death, the probability of receiving osimertinib as a second EGFR-TKI, and the median time from biopsy to receiving first-line gefitinib. RESULTS: Among 457 patients who received first-line treatment with gefitinib, those living in the most materially deprived areas had the shortest median survival time (ratio, high vs. low deprivation: 0.69; 95% CI: 0.47-1.04). The probability of receiving osimertinib as a second EGFR-TKI was highest for patients from immigrant-dense areas (ratio, high vs. lowdensity: 1.95; 95% CI: 1.26-3.36) or from Montreal (ratio, other urban areas vs. Montreal: 0.39; 95% CI: 0.16-0.71). The median wait time for gefitinib was 1.27 times longer in regions with health centers peripheral to large centers in Quebec or Montreal in comparison to regions with university-affiliated centers (95% CI: 1.09-1.54; n = 353). CONCLUSION: This study shows that real-world variations in survival and treatment exist among advanced lung cancer patients in the era of breakthrough therapies and that future research on inequalities should also focus on this population.

Advanced Lung Cancer Patients' Use of EGFR Tyrosine Kinase Inhibitors and Overall Survival: Real-World Evidence from Quebec, Canada.

EGFR tyrosine kinase inhibitors (EGFR-TKIs) are breakthrough palliative treatments for advanced lung cancer patients with tumors harboring mutations in the EGFR gene. Using healthcare administrative data, three cohorts were created to describe the use of three EGFR-TKIs that are publicly funded in Quebec for specific indications (i.e., 1st-line gefitinib, 1st-line afatinib, and post-EGFR-TKI osimertinib). The main objective was to compare overall survival (OS) among patients receiving these treatments to those in previous experimental and real-world studies. The patients who received EGFR-TKIs for indications of interest between 1 April 2001, and 31 March 2019 (or 31 March 2020, for post-EGFR-TKI osimertinib) were included to estimate the Kaplan-Meier-based median OS for each cohort. An extensive literature search was conducted to include comparable studies. For the gefitinib 1st-line (n = 457), the afatinib 1st-line (n = 80), and the post-EGFR-TKI osimertinib (n = 119) cohorts, we found a median OS (in months) of 18.9 (95%CI: 16.3-21.9), 26.6 (95%CI: 13.7-NE) and 19.9 (95%CI: 17.4-NE), respectively. Out of the 20 studies that we retained from the literature review and where comparisons were feasible, 17 (85%) had similar OS results, which further confirms the value of these breakthrough therapies in real-world clinical practice.

Cathepsin B promotes colorectal tumorigenesis, cell invasion, and metastasis.

Cathepsin B is a cysteine proteinase that primarily functions as an endopeptidase within endolysosomal compartments in normal cells. However, during tumoral expansion, the regulation of cathepsin B can be altered at multiple levels, thereby resulting in its overexpression and export outside of the cell. This may suggest a possible role of cathepsin B in alterations leading to cancer progression. The aim of this study was to determine the contribution of intracellular and extracellular cathepsin B in growth, tumorigenesis, and invasion of colorectal cancer (CRC) cells. Results show that mRNA and activated levels of cathepsin B were both increased in human adenomas and in CRCs of all stages. Treatment of CRC cells with the highly selective and non-permeant cathepsin B inhibitor Ca074 revealed that extracellular cathepsin B actively contributed to the invasiveness of human CRC cells while not essential for their growth in soft agar. Cathepsin B silencing by RNAi in human CRC cells inhibited their growth in soft agar, as well as their invasion capacity, tumoral expansion, and metastatic spread in immunodeficient mice. Higher levels of the cell cycle inhibitor p27(Kip1) were observed in cathepsin B-deficient tumors as well as an increase in cyclin B1. Finally, cathepsin B colocalized with p27(Kip1) within the lysosomes and efficiently degraded the inhibitor. In conclusion, the present data demonstrate that cathepsin B is a significant factor in colorectal tumor development, invasion, and metastatic spreading and may, therefore, represent a potential pharmacological target for colorectal tumor therapy.

Prise en charge de l'extravasation associée aux traitements antinéoplasiques: guide de pratique clinique / Management of extravasation associated with antineoplastic treatments: a clinical practice guide

CONTEXTE ET OBJECTIFS: L'extravasation est une complication potentiellement grave pouvant survenir au cours de l'administration de la chimiothérapie. Peu de données probantes sont disponibles pour permettre l'élaboration d'un schéma de prise en charge optimale. Le présent guide a été préparé par le Comité de l'évolution des pratiques en oncologie (CEPO) en collaboration avec le sous-comité dédié aux guides et aux conseils du Comité de l'évolution de la pratique des soins pharmaceutiques à la Direction québécoise de cancérologie du ministère de la Santé et des Services sociaux. L'objectif est de faire état de la documentation scientifique pertinente concernant la prise en charge et le traitement de l'extravasation survenue au cours de l'administration de chimiothérapie à des patients atteints de cancer. MÉTHODES: Une revue de la documentation scientifique a été effectuée dans l'outil de recherche Pubmed. La période couverte s'est étendue du début de l'existence de la banque jusqu'à avril 2014 inclusivement. La littérature concernant le traitement de l'extravasation est bien souvent empirique, anecdotique et controversée. Pour ces raisons, les recommandations pour la pratique clinique et les consensus d'experts publiés par certains organismes internationaux et agences de cancer ont également été répertoriés. Ils proviennent, notamment, de la British Columbia Cancer Agency (BCCA), de l'European Society of Medical Oncology (ESMO) en collaboration avec l'European Oncology Nursing Society (EONS), du Gippsland Oncology Nurses Group (GONG), du Humber and Yorkshire Coast Cancer Network (HYCCN), de l'Oncology Nursing Society (ONS) et du West of Scotland Cancer Advisory Network Clinical Leads Group (WOSCAN). RÉSULTATS: La détermination des facteurs de risque potentiels ainsi que l'application des méthodes de prévention peuvent diminuer les risques d'extravasation. La reconnaissance et la prise en charge des symptômes deviennent essentielles pour les patients touchés par cette complication. L'enseignement adéquat aux patients concernant les symptômes à surveiller de même qu'au personnel responsable de l'administration de la chimiothérapie, de la prévention et de la prise en charge de l'extravasation est essentiel. L'utilisation de compresses sèches tièdes ou froides ainsi que de divers antidotes déterminés en fonction de l'agent responsable permet de traiter l'extravasation. L'utilisation du diméthylsulfoxide (DMSO), de la dexrazoxane, de l'hyaluronidase ou du thiosulfate de sodium est recommandée selon l'agent en cause de l'extravasation. Une approche chirurgicale doit être considérée lorsque le traitement conservateur avec les antidotes est insuffisant ou en présence de morbidités sévères. Le suivi des patients permet d'évaluer la progression ou la régression des symptômes et ainsi de prendre les mesures appropriées. Le temps de suivi est variable selon les progrès cliniques observés. L'utilisation d'un gabarit validé permettra d'optimiser la collecte d'information. RECOMMANDATIONS: Considérant les données probantes disponibles à ce jour et les lignes directrices publiées par divers organismes (BCCA, ESMO-EONS, GONG, HYCCN, ONS et WOSCAN), le CEPO recommande (recommandation de grade D à moins d'avis contraire): Général: 1. Que toutes les chimiothérapies soient administrées dans des centres où le personnel est qualifié; 2. Que le personnel responsable de l'administration de la chimiothérapie reçoive une formation adéquate pour la prévention et la prise en charge de l'extravasation; 3. Qu'une procédure documentée et facilement accessible soit mise en place dans les centres administrant de la chimiothérapie. La présence d'une ou de plusieurs trousses destinées au traitement de l'extravasation est fortement conseillée; 4. Que les patients soient informés du risque possible d'extravasation, des mesures de prévention et qu'ils soient formés à reconnaître les premiers symptômes afin d'en aviser immédiatement le personnel; 5. Que le ou les agents vésicants soient administrés en premier lorsque plusieurs agents différents sont donnés, si le protocole le permet; Traitement: Extravasation par voie périphérique: 6. Qu'un type de compresse particulier soit utilisé en fonction de l'agent antinéoplasique ayant causé l'extravasation: a. Compresse sèche froide (0 oC, 20 à 30 minutes à la fois et répétée 4 fois par jour pour les 24 à 48 premières heures suivant l'extravasation); b. Compresse sèche tiède (44 à 50 oC, 20 à 30 minutes à la fois et répétée 4 fois par jour pour les 24 à 48 premières heures suivant l'extravasation) 7. Que le DMSO (99 %, 4 gouttes/10 cm2 aux 6 à 8 heures pour 7 à 14 jours à débuter dans les 10 premières minutes suivant l'extravasation) soit utilisé pour le traitement de l'extravasation aux agents suivants: a. Mitomycine C. b. Anthracyclines, à défaut d'une possibilité de traitement avec la dexrazoxane dans les 6 heures suivant l'extravasation; 8. Que la dexrazoxane (1 000 mg/m2 [maximum: 2 000 mg/dose] aux jours 1 et 2 puis 500 mg/m2 [maximum : 1 000 mg/dose] au jour 3) soit utilisée pour le traitement de l'extravasation aux anthracyclines (recommandation de grade A). Un réseau de distribution pourrait être mis en place pour faciliter la disponibilité du produit; 9. Que l'hyaluronidase (150 à 1 500 unités (U); 150 U/ml dans la voie ou 1 500 U/ml pour 5 injections de 0,2 ml) soit utilisée pour le traitement de l'extravasation aux alcaloïdes de la vinca. Un réseau de distribution pourrait être mis en place pour faciliter la disponibilité du produit; 10.Que les corticostéroïdes systémiques ne soient pas utilisés pour le traitement de l'extravasation; 11.Que les corticostéroïdes topiques soient utilisés si nécessaire pour le traitement de l'inflammation autour du site d'extravasation, sauf en présence d'alcaloïdes de la vinca et d'épipodophyllotoxines; 12.Qu'une consultation en chirurgie soit demandée si la condition médicale du patient le justifie; 13.Que soient appliquées les mesures de l'algorithme A-1 pour la prise en charge de l'extravasation par voie périphérique. Extravasation par voie centrale: 14.Que le diagnostic soit confirmé par veinographie ou par imagerie; 15.Que la dexrazoxane (1 000 mg/m2 [maximum: 2 000 mg/dose] aux jours 1 et 2 puis 500 mg/m2 [maximum : 1 000 mg/dose] au jour 3) soit utilisée pour le traitement de l'extravasation aux anthracyclines (recommandation de grade A); 16.Que soient appliquées les mesures de l'algorithme A-2 pour la prise en charge de l'extravasation par voie centrale (annexe A); Suivi et documentation: 17.Que chaque incident d'extravasation soit documenté dans le dossier médical et rapporté de manière exhaustive. L'utilisation d'un gabarit contenant toute l'information à recueillir est fortement conseillée; 18.Qu'un rapport d'incident soit complété (formulaire AH-223), suivant la politique locale de l'établissement; 19.Qu'un suivi soit fait aux 24 à 48 heures pendant la première semaine puis aux semaines si amélioration jusqu'à la résolution des symptômes.(AU)

BACKGROUND AND OBJECTIVES: Extravasation is a potentially serious complication that can occur during the administration of chemotherapy. There is little evidence for developing an optimal management scheme. This guideline was prepared by the Comité de l'évolution des pratiques en oncologie (CEPO) in cooperation with the guideline and advice subcommittee of the Comité de l'évolution de la pratique des soins pharmaceutiques of the Ministère de la Santé et des Services sociaux's Direction québécoise de cancérologie. The objective was to examine the relevant scientific literature on the management and treatment of extravasation that occurs when chemotherapy is administered to cancer patients. METHODS: A scientific literature review was conducted using the PubMed search tool. The period covered was from the inception of the database up to and including April 2014. The literature on the treatment of extravasation is very often empirical, anecdotal and much debated. For these reasons, the clinical practice recommendations and expert consensuses published by certain international organizations and cancer agencies were included as well. In particular, they are from the British Columbia Cancer Agency (BCCA), the European Society of Medical Oncology (ESMO) in conjunction with the European Oncology Nursing Society (EONS), the Gippsland Oncology Nurses Group (GONG), the Humber and Yorkshire Coast Cancer Network (HYCCN), the Oncology Nursing Society (ONS) and the West of Scotland Cancer Advisory Network Clinical Leads Group (WOSCAN). RESULTS: Determining the potential risk factors and taking preventive measures can reduce the risk of extravasation. Recognizing and managing the symptoms is essential in patients with this complication. Providing adequate instruction on the symptoms to watch for to patients and to personnel responsible for administering chemotherapy, preventing and managing extravasation is essential. Warm or cold, dry compresses and various antidotes, which are determined according to the agent involved, are used to treat extravasation. The use of dimethylsulfoxide (DMSO), dexrazoxane, hyaluronidase or sodium thiosulfate is recommended, depending on the agent that has extravasated. Consideration should be given to a surgical approach when conservative treatment with antidotes is inadequate or if the patient has severe morbidities. Patients are monitored to assess the progression or regression of symptoms and to thus take the appropriate measures. Monitoring time varies according to the observed clinical progress. A validated template can be used to optimize information gathering. RECOMMENDATIONS: Given the evidence available at this time and the guidelines published by various organizations (BCCA, ESMO-EONS, GONG, HYCCN, ONS and WOSCAN), the CEPO recommends (Grade D recommendation, unless indicated otherwise): General: 1. That all chemotherapies be administered at facilities whose personnel are qualified; 2. That personnel responsible for administering chemotherapy be adequately trained in extravasation prevention and management; 3. That a written and easily accessible procedure be established at facilities that administer chemotherapy. Having one or more extravasation treatment kits on hand is strongly advised; 4. That patients be informed of the potential risk of extravasation and of the preventive measures, and that they be trained to recognize the initial symptoms so that they can inform the personnel at once; 5. That the vesicant or vesicants be administered first when several different agents are to be given, if the protocol allows this; TREATMENT: Peripheral extravasation: 6. That a specific type of compress be used according to the extravasated antineoplastic agent: a) A cold, dry compress (0 °C, 20 to 30 minutes at a time and repeated 4 times a day for the first 24 to 48 hours after the extravasation. b. A warm, dry compress (44 to 50 °C, 20 to 30 minutes at a time and repeated 4 times a day for the first 24 to 48 hours after the extravasation). 7. That DMSO (99%, 4 drops/10 cm2 every 6 to 8 hours for 7 to 14 days, starting within the first 10 minutes after the extravasation) be used to treat extravasation of the following agents: a.) Mitomycin C; b) Anthracyclines, if treatment with dexrazoxane within the first 6 hours after the extravasation is not possible. 8. That dexrazoxane (1000 mg/m2 [maximum: 2000 mg/dose] on days 1 and 2, then 500 mg/m2 [maximum: 1000 mg/dose] on day 3) be used to treat the extravasation of anthracyclines (Grade A recommendation). A distribution network could be put in place to facilitate access to dexrazoxane; 9. That hyaluronidase (150 to 1500 units (U); 150 U/mL into the line or 1500 U/mL for five 0.2-mL injections) be used to treat the extravasation of vinca alkaloids. A distribution network could be put in place to facilitate access to hyaluronidase; 10.That systemic corticosteroids not be used to treat extravasation; 11. That topical corticosteroids be used if necessary to treat inflammation around the extravasation site, except if the patient is receiving vinca alkaloids or epipodophyllotoxins; 12.That a surgical consultation be requested if warranted by the patient's medical condition; 13.That the measures indicated in Algorithm A-1 be taken to manage peripheral extravasation; Central extravasation: 14.That the diagnosis be confirmed by venography or imaging; 15.That dexrazoxane (1000 mg/m2 [maximum: 2000 mg/dose] on days 1 and 2, then 500 mg/m2 [maximum: 1000 mg/dose] on day 3) be used to treat the extravasation of anthracyclines (Grade A recommendation); 16.That the measures indicated in Algorithm A-2 be taken to manage central extravasation; Follow-up and documentation: 17.That each extravasation incident be recorded in the patient's chart and exhaustively reported. The use of a template indicating all the information that needs to be gathered is strongly recommended; 18.That an incident report be completed (Form AH-223) in accordance with the facility's local policy; 19.That a follow-up be done every 24 to 48 hours during the first week, then every week, if there is improvement, until the symptoms resolve.(AU)

Laparoscopic versus open surgery for the treatment of colorectal cancer: a literature review and recommendations from the Comité de l'évolution des pratiques en oncologie.

BACKGROUND: Adoption of the laparoscopic approach for colorectal cancer treatment has been slow owing to initial case study results suggesting high recurrence rates at port sites. The use of laparoscopic surgery for colorectal cancer still raises a number of concerns, particularly with the technique's complexity, learning curve and longer duration. After exploring the scientific literature comparing open and laparoscopic surgery for the treatment of colorectal cancer with respect to oncologic efficacy and shortterm outcomes, the Comité de l'évolution des pratiques en oncologie (CEPO) made recommendations for surgical practice in Quebec. METHODS: Scientific literature published from January 1995 to April 2012 was reviewed. Phase III clinical trials and meta-analyses were included. RESULTS: Sixteen randomized trials and 10 meta-analyses were retrieved. Analysis of the literature confirmed that for curative treatment of colorectal cancer, laparoscopy is not inferior to open surgery with respect to survival and recurrence rates. Moreover, laparoscopic surgery provides short-term advantages, including a shorter hospital stay, reduced analgesic use and faster recovery of intestinal function. However, this approach does require a longer operative time. CONCLUSION: Considering the evidence, the CEPO recommends that laparoscopic resection be considered an option for the curative treatment of colon and rectal cancer; that decisions regarding surgical approach take into consideration surgeon experience, tumour stage, potential contraindications and patient expectations; and that laparoscopic resection for rectal cancer be performed only by appropriately trained surgeons who perform a sufficient volume annually to maintain competence.

CONTEXTE: L'adoption de la laparoscopie pour traiter le cancer colorectal se fait lentement à cause des résultats des premières études de cas qui indiquent des taux élevés de récidive aux sites d'intervention. La laparoscopie pour traiter le cancer colorectal soulève toujours de nombreuses préoccupations, particulièrement en raison de la complexité de la technique, de la courbe d'apprentissage, et de la durée de la chirurgie. Après avoir étudié des publications scientifiques comparant l'efficacité oncologique et les résultats à court terme de la laparoscopie à ceux de la chirurgie ouverte pour le traitement du cancer colorectal, le Comité de l'évolution des pratiques en oncologie (CEPO) a formulé des recommandations pour la pratique chirurgicale au Québec. MÉTHODES: Une revue des écrits scientifiques publiés entre janvier 1995 et avril 2012 a été effectuée. Seuls les essais cliniques de phase III et les méta-analyses ont été répertoriés. RÉSULTANTS: Seize essais randomisés et 10 méta-analyses ont été retenus. L'analyse des publications a confirmé que pour le traitement curatif du cancer colorectal, la laparoscopie n'est pas inférieure à la chirurgie ouverte pour ce qui est des taux de survie et de récidive. La laparoscopie offre de plus des avantages à court terme, y compris une hospitalisation de moins longue durée, une réduction de l'usage d'analgésiques et un rétablissement plus rapide de la fonction intestinale. Cette intervention prend toutefois plus de temps. CONCLUSIONS: Compte tenu des données probantes, le CEPO recommande d'envisager la résection laparoscopique comme technique curative possible du cancer colorectal et que les décisions sur la méthode chirurgicale tiennent compte de l'expérience du chirurgien, du stade de la tumeur, des contre-indications possibles et des attentes du patient. Dans le cas de la résection laparoscopique du cancer du rectum, le CEPO recommande qu'elle ne soit pratiquée que par des chirurgiens ayant reçu la formation nécessaire et qui pratiquent suffisamment d'interventions par année pour maintenir leur compétence.

Adjuvant treatment for endometrial cancer: literature review and recommendations by the Comité de l'évolution des pratiques en oncologie (CEPO).

OBJECTIVE: Despite the very good prognosis of endometrial cancer, a number of patients with localized disease relapse following surgery. Therefore, various adjuvant therapeutic approaches have been studied. The objective of this review is to evaluate the efficacy and safety of neoadjuvant and adjuvant therapies in patients with resectable endometrial cancer and to develop evidence-based recommendations. METHODS: A review of the scientific literature published between January 1990 and June 2012 was performed. The search was limited to published phase III clinical trials and meta-analyses evaluating the efficacy of neoadjuvant or adjuvant therapies in patients with endometrial carcinoma or carcinosarcoma. A total of 23 studies and five meta-analyses were identified. RESULTS: The selected literature showed that in patients with a low risk of recurrence, post-surgical observation is safe and recommended in most cases. There are several therapeutic modalities available for treatment of endometrial cancers with higher risk of recurrence, including vaginal brachytherapy, external beam radiotherapy, chemotherapy, or a combination of these. CONCLUSIONS: Considering the evidence available to date, the CEPO recommends the following: (1)post-surgical observation for most patients with a low recurrence risk; (2)adjuvant vaginal brachytherapy for patients with an intermediate recurrence risk; (3)adjuvant pelvic radiotherapy with or without vaginal brachytherapy for patients with a high recurrence risk; addition of adjuvant chemotherapy may be considered as an option for selected patients (excellent functional status, no significant co-morbidities, poor prognostic factors); (4)adjuvant chemotherapy and pelvic radiotherapy with or without brachytherapy and para-aortic irradiation for patients with advanced disease;

Epithelial polarity proteins regulate Drosophila tracheal tube size in parallel to the luminal matrix pathway.

Regulation of epithelial tube size is critical for organ function. However, the mechanisms of tube size control remain poorly understood. In the Drosophila trachea, tube dimensions are regulated by a luminal extracellular matrix (ECM). ECM organization requires apical (luminal) secretion of the protein Vermiform (Verm), which depends on the basolateral septate junction (SJ). Here, we show that apical and basolateral epithelial polarity proteins interact to control tracheal tube size independently of the Verm pathway. Mutations in yurt (yrt) and scribble (scrib), which encode SJ-associated polarity proteins, cause an expansion of tracheal tubes but do not disrupt Verm secretion. Reducing activity of the apical polarity protein Crumbs (Crb) suppresses the length defects in yrt but not scrib mutants, suggesting that Yrt acts by negatively regulating Crb. Conversely, Crb overexpression increases tracheal tube dimensions. Reducing crb dosage also rescues tracheal size defects caused by mutations in coracle (cora), which encodes an SJ-associated polarity protein. In addition, crb mutations suppress cora length defects without restoring Verm secretion. Together, these data indicate that Yrt, Cora, Crb, and Scrib operate independently of the Verm pathway. Our data support a model in which Cora and Yrt act through Crb to regulate epithelial tube size.

Activation of Cdk2 stimulates proteasome-dependent truncation of tyrosine phosphatase SHP-1 in human proliferating intestinal epithelial cells.

SHP-1 is expressed in the nuclei of intestinal epithelial cells (IECs). Increased SHP-1 expression and phosphatase activity coincide with cell cycle arrest and differentiation in these cells. Suspecting the tumor-suppressive properties of SHP-1, a yeast two-hybrid screen of an IEC cDNA library was conducted using the full-length SHP-1 as bait. Characterization of many positive clones revealed sequences identical to a segment of the Cdk2 cDNA sequence. Interaction between SHP-1 and Cdk2 was confirmed by co-immunoprecipitations whereby co-precipitated Cdk2 phosphorylated SHP-1 protein. Inhibition of Cdk2 (roscovitine) or proteasome (MG132) was associated with an enhanced nuclear punctuate distribution of SHP-1. Double labeling localization studies with signature proteins of subnuclear domains revealed a co-localization between the splicing factor SC35 and SHP-1 in bright nucleoplasmic foci. Using Western blot analyses with the anti-SHP-1 antibody recognizing the C terminus, a lower molecular mass species of 45 kDa was observed in addition to the full-length 64-65-kDa SHP-1 protein. Treatment with MG132 led to an increase in expression of the full-length SHP-1 protein while concomitantly leading to a decrease in the levels of the lower mass 45-kDa molecular species. Further Western blots revealed that the 45-kDa protein corresponds to the C-terminal portion of SHP-1 generated from proteasome activity. Mutational analysis of Tyr(208) and Ser(591) (a Cdk2 phosphorylation site) residues on SHP-1 abolished the expression of the amino-truncated 45-kDa SHP-1 protein. In conclusion, our results indicate that Cdk2-associated complexes, by targeting SHP-1 for proteolysis, counteract the ability of SHP-1 to block cell cycle progression of IECs.

Cdk2-dependent phosphorylation of homeobox transcription factor CDX2 regulates its nuclear translocation and proteasome-mediated degradation in human intestinal epithelial cells.

By having demonstrated previously that p27(Kip1), a potent inhibitor of G(1) cyclin-cyclin-dependent kinases complexes, increases markedly during intestinal epithelial cell differentiation, we examined the effect of p27(Kip1) on the activity of the transcription factor CDX2. The present results revealed the following. 1) p27(Kip1) interacts with the CDX2 transcription factor. 2) In contrast to CDX2 mRNA levels, CDX2 protein expression levels significantly increased as soon as Caco-2/15 cells reached confluence, slowed their proliferation, and began their differentiation. The mechanism of CDX2 regulation is primarily related to protein stability, because inhibition of proteasome activity increased CDX2 levels. The half-life of CDX2 protein was significantly enhanced in differentiated versus undifferentiated proliferative intestinal epithelial cells. 3) Cdk2 interacted with CDX2 and phosphorylated CDX2, as determined by pull-down glutathione S-transferase and immunoprecipitation experiments with proliferating undifferentiated Caco-2/15 cell extracts. 4) Treatment of Caco-2/15 cells with MG132 (a proteasome inhibitor) and (R)-roscovitine (a specific Cdk2 inhibitor) induced an increase in CDX2 protein levels. 5) Conversely, ectopic expression of Cdk2 resulted in decreased expression of CDX2 protein. 6) Of note, treatment of proliferative Caco-2/15 cells with (R)-roscovitine or leptomycin (an inhibitor of nuclear export through CRM1) led to an accumulation of CDX2 into the nucleus. These data suggest that CDX2 undergoes CRM1-dependent nuclear export and cytoplasmic degradation in cells in which Cdk2 is activated, such as in proliferative intestinal epithelial cells. The targeted degradation of CDX2 following its phosphorylation by Cdk2 identifies a new mechanism through which CDX2 activity can be regulated in coordination with the cell cycle machinery.