Pre-mRNA splicing of IgM exons M1 and M2 is directed by a juxtaposed splicing enhancer and inhibitor

Splicing of certain pre-mRNA introns is dependent on an enhancer element, which is typically purine-rich. It is generally thought that enhancers increase the use of suboptimal splicing signals, and one specific proposal is that enhancers stabilize binding of U2AF65 to weak polypyrimidine (Py) tracts. Here, we test this model using an IgM pre-mRNA substrate, which contains a well-characterized enhancer. Although the enhancer was required for in vitro splicing, we found it had no effect on U2AF65 binding. Unexpectedly, replacement of the natural IgM Py tract, branchpoint, and 5' splice site with consensus splicing signals did not circumvent the enhancer requirement. These observations led us to identify a novel regulatory element within the IgM M2 exon that acts as a splicing inhibitor; removal of the inhibitor enabled splicing to occur in the absence of the enhancer. The IgM M2 splicing inhibitor is evolutionarily conserved, can inhibit the activity of an unrelated, constitutively spliced pre-mRNA, and acts by repressing splicing complex assembly. Interestingly, the inhibitor itself forms an ATP-dependent complex that contains U2 snRNP. We conclude that splicing of IgM exons M1 and M2 is directed by two juxtaposed regulatory elements-an enhancer and an inhibitor-and that a primary function of the enhancer is to counteract the inhibitor.

Overview of MTA in the treatment of non-small cell lung cancer

While advanced non-small cell lung cancer is a malignancy which remains largely refractory to chemotherapy, the 1990s have seen gains in both the number of agents available as well as the frequency of use of these agents in the treatment of non-small cell lung cancer. This report reviews several studies of MTA (multitargeted antifolate, LY23 1514), a novel antifolate, as first- and second-line treatment. MTA has been tested in advanced non-small cell lung cancer in a variety of patient populations, including those who have received no prior chemotherapy, those who have relapsed following prior platinum-containing therapy, and those who have relapsed following prior chemotherapy which did not contain platinum. In both groups MTA was found to be active, its activity in chemonaive patients was comparable (14%-23%) to currently used new drugs like taxanes and gemcitabine. Additionally, MTA has been studied in combination with cisplatin in patients who are chemotherapy-naive, with a response rate (42%) comparable to other modern combination regimens. Preliminary data appear promising and will be discussed.

Is quality of life predictive of the survival of patients with advanced nonsmall cell lung carcinoma?

BACKGROUND

Several studies have recently reported on the importance of quality of life (QOL) in predicting the survival of patients with lung carcinoma. To confirm these reports, the relationship between survival and QOL, as measured by the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire and Duke-UNC Social Support Scale, was examined within a group of 206 patients with advanced nonsmall cell lung carcinoma treated in a randomized clinical trial conducted by the Cancer and Leukemia Group B (CALGB 8931).

METHODS

Patients completed the EORTC instrument and the Duke-UNC Social Support Scale at baseline in the clinic. The Cox proportional hazards model was used to determine the incremental contribution QOL provided in predicting survival beyond the effect of known clinical prognostic variables.

RESULTS

Clinical factors that were jointly predictive of poorer survival included low performance status, nonadenocarcinoma histology, presence of dyspnea, weight loss greater than 5%, albumin level less than 3.5 mg/dL, and adrenal metastases. Univariate analyses showed that patient-reported EORTC subscales describing increased pain, appetite loss, fatigue, lung carcinoma symptoms, poorer overall QOL, and poorer physical functioning predicted significantly poorer survival. Multivariate analyses showed that, after adjustment for clinical factors, overall QOL was not a significant predictor of survival. Rather, the only EORTC subscale of prognostic importance was the pain subscale, in which a 40-point increase was associated with a 27% increase in the hazard rate.

CONCLUSIONS

This study did not confirm the prognostic importance of overall QOL. Rather, after adjustment for significant clinical factors, a patient-provided pain report had the greatest prognostic importance.

Radiosensitization with carboplatin for patients with unresectable stage III non-small-cell lung cancer: a phase III trial of the Cancer and Leukemia Group B and the Eastern Cooperative Oncology Group

PURPOSE

To determine whether the administration of carboplatin concurrently with radiation treatment improves survival in patients with inoperable stage III non-small-cell lung cancer.

PATIENTS AND METHODS

Two hundred eighty-three patients with inoperable stage III non-small-cell lung cancer were entered onto a randomized trial by the Cancer and Leukemia Group B and the Eastern Cooperative Oncology Group. Randomization was performed before initiation of any therapy. All patients received an induction chemotherapy program with vinblastine and cisplatin for 5 weeks, followed by 6,000 cGy of radiation therapy over 6 weeks. One hundred thirty-seven patients were randomized to this therapy regimen alone; 146 patients were randomized to receive carboplatin at 100 mg/m2/wk concurrent with the radiation therapy.

RESULTS

The complete response was 18% with concurrent carboplatin versus 10% with radiotherapy alone (P = .101). There was no difference with respect to failure-free survival (10% with carboplatin and 9% with radiotherapy alone) or overall survival (13% with carboplatin and 10% with radiotherapy alone) at 4 years. In patients not receiving carboplatin, the relapse rate was 69% within the field of radiation and 53% in the boost volume. In patients receiving carboplatin, the relapse rate was 59% within the field of radiation and 43% in the boost volume. Patients with cancers more than 70 cm2 in size had significantly poorer survival (P = .01).

CONCLUSION

Carboplatin at the dose and schedule used did not significantly impact on disease control or survival. The relapse rate within the chest remained more than 50%. More effective regimens will be required to impact on local disease control and survival.

A novel member of the NF2/ERM/4.1 superfamily with growth suppressing properties in lung cancer

A novel putative tumor suppressor gene and member of the NF2/ERM/ 4.1 superfamily was isolated using Differential Display PCR (DDPCR) on primary lung tumors. When reintroduced into nonexpressing non-small cell lung carcinoma cell lines, this gene, named DAL-1 (for Differentially expressed in Adenocarcinoma of the Lung), was shown to suppress growth. In addition, significantly reduced expression (>50%) of DAL-1 was measured in 39 primary non-small cell lung carcinoma tumors as compared with patient-matched normal lung tissue. Immunocytochemical staining with a polyclonal anti-DAL-1 antibody localized the protein to the plasma membrane, particularly at cell-cell contact points, a pattern reminiscent of other members of the protein 4.1 superfamily including ezrin and NF2. The data suggest DAL-1 is a novel membrane-associated protein with potential to play an important role in the origin and progression of lung cancer.

The 1997 International Staging System for non-small cell lung cancer: have all the issues been addressed?

The International Staging System for Lung Cancer has been revised recently. Important changes have been made to allow better correlation of prognoses and direction of management. The classification of synchronous pulmonary nodules in the same lobe as the primary tumor as T4 stage IIIB may imply a poorer outcome than is warranted, while the designation of a similar stage for malignant pleural effusion may not be reflective of the very poor prognosis associated with this extent of disease.

Analysis of selective gene activation in yeast by differential display

TATA box binding protein-associated factors (TAF(II)s) are dispensable for transcription of most genes in yeast. To further investigate the in vivo functions of TAF(II)s, differential display was used to identify a small subset of yeast genes whose transcription is dependent on yeast TAF(II)145, the core TAF(II) component that contacts TATA box-binding protein (TBP). Messenger RNA profiles derived from a wild-type TAF(II)145 strain and a temperature-sensitive taf(II)1145 strain were analyzed. Those genes whose messenger RNA level was greatly reduced in the temperature-sensitive taf(II)145 strain were cloned and further characterized. The procedure for performing differential display described here is modified from protocols provided by the manufacturer (Display Systems) and optimized for the yeast system.

Dissecting the regulatory circuitry of a eukaryotic genome

Genome-wide expression analysis was used to identify genes whose expression depends on the functions of key components of the transcription initiation machinery in yeast. Components of the RNA polymerase II holoenzyme, the general transcription factor TFIID, and the SAGA chromatin modification complex were found to have roles in expression of distinct sets of genes. The results reveal an unanticipated level of regulation which is superimposed on that due to gene-specific transcription factors, a novel mechanism for coordinate regulation of specific sets of genes when cells encounter limiting nutrients, and evidence that the ultimate targets of signal transduction pathways can be identified within the initiation apparatus.

Broad, but not universal, transcriptional requirement for yTAFII17, a histone H3-like TAFII present in TFIID and SAGA

The RNA polymerase II general transcription factor TFIID is a multisubunit complex comprising TATA box-binding protein (TBP) and associated factors (TAFIIs). Experiments in yeast have shown that although most TAFIIs are required for viability, many genes are transcribed normally upon inactivation of individual and even multiple yTAFIIs. Here we analyze yTAFII17, recently found to be present in both the SAGA HAT complex as well as TFIID. Functional inactivation of yTAFII17 by temperature-sensitive mutation or depletion results in loss of transcription of many, but not all, genes. The upstream activating sequence (UAS), which contains the activator binding sites, is the region that renders a gene yTAFII17 dependent. In conjunction with previous studies, our results reveal that different TAFIIs have remarkably distinct properties.

Controlling gene expression in living cells through small molecule-RNA interactions

Short RNA aptamers that specifically bind to a wide variety of ligands in vitro can be isolated from randomized pools of RNA. Here it is shown that small molecule aptamers also bound their ligand in vivo, enabling development of a method for controlling gene expression in living cells. Insertion of a small molecule aptamer into the 5' untranslated region of a messenger RNA allowed its translation to be repressible by ligand addition in vitro as well as in mammalian cells. The ability of small molecules to control expression of specific genes could facilitate studies in many areas of biology and medicine.

The HIV-1 Tat cellular coactivator Tat-SF1 is a general transcription elongation factor

The human immunodeficiency virus type 1 (HIV-1) Tat protein strongly and specifically stimulates transcription elongation from the HIV-1 LTR and provides an important in vitro model system to study this process. Here we use protein-affinity chromatography to identify cellular factors involved in transcription elongation. A Tat-affinity column bound one transcription factor, Tat-SF1, efficiently and selectively. Tat-SF1 was identified originally as a Tat-specific coactivator, but we show it is a general transcription elongation factor. Our results also reveal the existence of an ATP-inactivatable general elongation factor (AIEF) required for Tat-SF1 activity and for which Tat can substitute functionally.

Analysis of neuroendocrine markers, HER2 and CEA before and after chemotherapy in patients with stage IIIA non-small cell lung cancer: a Cancer and Leukemia Group B study

Several studies have suggested that biochemical or molecular markers examined in non-small cell lung cancer carry prognostic or treatment response information. Non-small cell lung cancer patients whose tumors have neuroendocrine (NE) features may be more responsive to chemotherapy. In addition, increased expression of HER2 (c-erbB-2), a membrane-bound receptor with tyrosine kinase activity, has been associated with shortened survival. The Cancer and Leukemia Group B (CALGB) performed a study of patients with stage IIIA (N2 nodes positive) non-small cell lung cancer in which patients received initial chemotherapy followed by surgery, then post-operative therapy consisting of sequential chemotherapy and radiation therapy. Since all patients underwent mediastinoscopy, this provided an opportunity to compare pre- and post-chemotherapy tumor specimens to test the hypothesis that these proteins would predict treatment response. In particular, we hypothesized that the post-chemotherapy specimens would be enriched for NE marker negative cells because of the increased sensitivity of NE positive cells to chemotherapy. We performed immunohistochemical analysis for a panel of NE markers [neuron-specific enolase (NSE), Leu-7, chromogranin A (ChrA), synaptophysin (Syn)], HER2 and CEA to determine if there was an effect of therapy on the percentage of cells expressing these markers. Secondary endpoints were a correlation with chemotherapy response and survival. Slides were scored for intensity (0-4) and percentage of cells positive (0-4). Of 61 eligible patients, there were 38 with both pre- and post-chemotherapy specimens. When both intensity of staining and percentage of positive cells were considered, post-chemotherapy specimens had a higher percentage of positive NE markers compared with pre-chemotherapy. In addition, there was no correlation between NE marker, HER2 or CEA expression (prior to or post treatment) and response to chemotherapy or survival. These data do not support the hypothesis that NE positive tumor cells are preferentially killed by chemotherapy in patients with stage IIIA non-small cell lung cancer.

Dose and dose intensity as determinants of outcome in the adjuvant treatment of breast cancer. The Cancer and Leukemia Group B

BACKGROUND

Both total dose and dose intensity of adjuvant chemotherapy are postulated to be important variables in the outcome for patients with operable breast cancer. The Cancer and Leukemia Group B study 8541 examined the effects of adjuvant treatment using conventional-range dose and dose intensity in female patients with stage II (axillary lymph node-positive) breast cancer.

METHODS

Within 6 weeks of surgery (radical mastectomy, modified radical mastectomy, or lumpectomy), 1550 patients with unilateral breast cancer were randomly assigned to one of three treatment arms: high-, moderate-, or low-dose intensity. The patients received cyclophosphamide, doxorubicin, and 5-fluorouracil on day 1 of each chemotherapy cycle, with 5-fluorouracil administration repeated on day 8. The high-dose arm had twice the dose intensity and twice the drug dose as the low-dose arm. The moderate-dose arm had two thirds the dose intensity as the high-dose arm but the same total drug dose. Disease-free survival and overall survival were primary end points of the study.

RESULTS

At a median follow-up of 9 years, disease-free survival and overall survival for patients on the moderate- and high-dose arms are superior to the corresponding survival measures for patients on the low-dose arm (two-sided P<.0001 and two-sided P = .004, respectively), with no difference in disease-free or overall survival between the moderate- and the high-dose arms. At 5 years, overall survival (average +/- standard error) is 79% +/- 2% for patients on the high-dose arm, 77% +/- 2% for the patients on the moderate-dose arm, and 72% +/- 2% for patients on the low-dose arm; disease-free survival is 66% +/- 2%, 61% +/- 2%, and 56% +/- 2%, respectively.

CONCLUSION

Within the conventional dose range for this chemotherapy regimen, a higher dose is associated with better disease-free survival and overall survival.

Combined cisplatin and gemcitabine for non-small cell lung cancer: influence of scheduling on toxicity and drug delivery

The scheduling of cytotoxic chemotherapy has important bearing on the toxicity and ability to deliver chemotherapy at or close to full dose. We report new data on the influence of different schedules of cisplatin and gemcitabine on toxicity and drug delivery in phase II studies of non-small cell lung cancer. Patients in six phase II studies had standard entry criteria for advanced non-small cell lung cancer. Whereas gemcitabine was given on days 1, 8, and 15 of a 28-day cycle in all these studies, the scheduling of cisplatin varied and was given either on day 1, day 2, day 15 (in two studies), or days 1, 8, and 15 (in two studies). The protocol dose per infusion for gemcitabine was 1,000 mg/m2 (five studies) and 1,500 mg/m2 (one study); for cisplatin, it was 100 mg/m2 when given once per cycle and 30 mg/m2 when given on days 1, 8, and 15. Similar dose reduction schedules were implemented in the event of grade 3 or higher drug toxicity for all studies except for the day 1 cisplatin study, in which the dose was omitted for grade 2 thrombocytopenia. Nonhematologic toxicity was very low. Hematologic toxicity was moderate, and in patients who developed grade 3 or 4 toxicity, there was no hemorrhage from thrombocytopenia and neutropenic sepsis was rare. The incidence of grade 3 or 4 thrombocytopenia with the day 1, day 2, day 15 (two studies combined), and days 1, 8, and 15 (two studies combined) cisplatin regimens was 50%, 52%, 26%, and 38%. The incidence of grade 3 or 4 neutropenia with these four regimens was 51%, 37%, 56%, and 49%, respectively. Although the hematologic toxicity might appear relatively similar, it represents the toxicity at the administered rather than the intended (protocol) dose, because drug delivery was reduced or omitted in the event of grade 3 or 4 toxicity. Differences between the schedules are revealed by analysis of the actual dosages delivered. The median dosage of gemcitabine per scheduled infusion was statistically higher with the day 15 cisplatin regimens (combined) compared with any of the other regimens treating at 1,000 mg/m2 (P < .003, z-score). The dose with the day 1, day 2, day 15, and days 1, 8, and 15 cisplatin regimens was 664, 829, 889, and 774 mg/m2, respectively. Both the percentages of cycles in which gemcitabine infusions were given at full dose and in which there were no omissions of gemcitabine infusions (including infusions with dose reductions) were statistically higher in the day 15 cisplatin regimen than with any of the other regimens (P < .0001, chi-square test). The percentage of cycles containing full-dose gemcitabine with the day 1, day 2, day 15, and days 1, 8, and 15 cisplatin regimens was 24%, 44%, 75%, and 46%, respectively. The percentage of cycles in which there were no omissions of gemcitabine infusions for the four regimens above was 32%, 55%, 83%, and 72%, respectively. Apart from the once-weekly regimen (days 1, 8, and 15) in which the protocol gemcitabine dose was 1,250 mg/m2, the day 15 cisplatin schedule allowed for the highest median concentration of gemcitabine. More importantly, the day 15 cisplatin schedule provided the longest duration of gemcitabine exposure, which is particularly important for its activity as gemcitabine is a phase-specific agent. The day 15 cisplatin schedule is associated with the best dose intensity and the longest median duration of exposure to gemcitabine, and best meets the goal of administering both agents at full doses in combination.

Thoracic radiation therapy added to chemotherapy for small-cell lung cancer: an update of Cancer and Leukemia Group B Study 8083

PURPOSE

To provide a 10-year update of the experience of the Cancer and Leukemia Group B (CALGB) in the addition of thoracic radiation therapy to chemotherapy in limited-stage small-cell lung cancer.

PATIENTS AND METHODS

Three hundred ninety-nine patients with limited-stage small-cell lung cancer were randomized to receive thoracic radiation therapy that started on day 1 (arm I) or day 64 of chemotherapy treatment (arm II), or chemotherapy alone with cyclophosphamide, vincristine, and etoposide (later, doxorubicin). Thoracic radiation therapy consisted of 4,000 rad to the tumor and mediastinum with a 1,000-rad boost. All patients received prophylactic cranial radiation to a dose of 3,000 rad.

RESULTS

Arm I patients had a median survival of 13.04 months, arm II patients 14.54 months, and arm III patients 13.58 months (log-rank test, P = .0072). Median time to clinical failure was 11 months in arm I, 11.21 months in arm II, and 8.7 months in arm III (log-rank test, P = .0004).

CONCLUSION

With 10 years of follow-up, the two arms that included thoracic radiation therapy remain superior to chemotherapy alone. The addition of thoracic radiation therapy to combination chemotherapy improved both complete response rates and survival, with increased but acceptable toxicity.

Psychologic and neuropsychologic functioning of patients with limited small-cell lung cancer treated with chemotherapy and radiation therapy with or without warfarin: a study by the Cancer and Leukemia Group B

PURPOSE

The current study assessed the psychologic and neuropsychologic functioning of patients with small-cell lung cancer who were randomized in a large clinical trial to receive intensive doxorubicin, cyclophosphamide, etoposide (ACE)/cisplatin, cyclophosphamide, etoposide (PCE) chemotherapy and radiation therapy (RT) to the primary tumor and prophylactic whole-brain irradiation with (regimen I) or without (regimen II) warfarin.

PATIENTS AND METHODS

Patients' emotional states and cognitive functioning were assessed using the Profile of Mood States (POMS) and Trail Making B Test (Trails B), respectively. Two hundred ninety-five patients completed the POMS and Trails B at pretreatment, 224 patients after the completion of the ACE course of chemotherapy (week 9), and 177 patients after the completion of the PCE chemotherapy and RT (week 17).

RESULTS

No differences on the POMS or Trails B measures were found between the two treatment arms as predicted, given that the only difference between the two treatment arms was the presence or absence of warfarin. Analysis of the POMS revealed that, overall, mean scores remained stable over the course of treatment; however, women showed a trend toward higher mean scores, which indicated a higher level of distress, compared with men at the pretreatment assessment. Examination of cognitive functioning, measured by the Trails B, revealed improved performance from baseline to post-ACE chemotherapy, which is consistent with a practice effect, but a significant worsening of Trails B scores post-RT compared with the pre-RT assessments, which is consistent with impaired cognitive functioning because of treatment (P < .0001).

CONCLUSION

Emotional state, measured by the POMS, did not differ between the groups or change significantly over time in this study of small-cell lung cancer patients treated with a combination of chemotherapy and RT plus or minus warfarin. However, the pattern of relatively stable POMS scores and poorer Trails B performance post-RT suggested that this combination of chemotherapy and RT had a negative impact on cognitive functioning.

Dihydro-5-azacytidine and cisplatin in the treatment of malignant mesothelioma: a phase II study by the Cancer and Leukemia Group B

BACKGROUND

In a prior Cancer and Leukemia Group B (CALGB) Phase II trial of patients with advanced, previously untreated mesothelioma, dihydro-5-azacytidine (DHAC) demonstrated a 17% response rate, including 1 complete response, with only mild myelosuppression. This Phase II study (CALGB 9031) was conducted to determine the effectiveness of and toxicities that would result from adding cisplatin to DHAC administered to the same patient population.

METHODS

Thirty-six patients were treated with concurrent DHAC at 1500 mg/m2/day for 5 days by continuous infusion and cisplatin 15 mg/m2 daily for 5 days. Therapy was repeated every 3 weeks. Cisplatin was to be increased to 20 mg/m2 daily in subsequent cycles if toxicity was minimal. Therapy was continued until disease progression or excessive toxicity mandated discontinuation.

RESULTS

Overall, 5 objective responses were observed in 29 evaluated patients (objective response rate, 17%). The median duration of response was 6.6 months. Median survival was 6.4 months, with a median time to clinical failure of 2.7 months. The major toxicity noted was significant chest/pericardial pain, as was observed with DHAC alone. There were 2 early deaths of unknown cause on Days 9 and 17 of therapy, respectively. Significant leukopenia was observed in 29% of patients, but there were no neutropenic fevers.

CONCLUSIONS

The addition of cisplatin to DHAC did not increase the response rate over that observed with DHAC alone in patients with mesothelioma; however, it did increase toxicity, especially leukopenia. This combination is not recommended for further studies involving mesothelioma patients.

Matrix-assisted laser desorption/ionization-collision induced dissociation of poly(styrene)

Matrix-assisted laser desorption/ionization-collision induced dissociation (MALDI-CID) has been employed for the analysis of poly(styrene) in a tandem hybrid sector-time of flight instrument. Spectra are shown for adducts of poly(styrene) with copper and silver ions. The distributions of fragment ion peaks were found to be consistent from precursor ions containing both metal ions. It is shown how the masses of the end groups of the polymer may be inferred from the mass-to-charge ratios of two of the series of ion peaks that are seen in the MALDI-CID spectra. Mechanisms are proposed for the formation of some of the other series of ion peaks that are observed in the spectra.

Clinical studies in non-small cell lung cancer: the CALGB experience

Since 1984, the Cancer and Leukemia Group B (CALGB) has focused its clinical research in stage IV non-small cell lung cancer (NSCLC) on investigations of new agents and combinations. Currently, efforts are aimed at identifying non-cisplatin-based combinations with an increased therapeutic index. In stage III disease multimodality therapies have been pursued. Dillman et al. reported a study comparing standard radiotherapy versus induction chemotherapy followed by radiotherapy in patients with unresectable stage III NSCLC. The chemotherapy-treated patients were found to benefit with a 4-month increase in median survival time compared with patients receiving radiotherapy alone (13.8 vs. 9.7 months) and an increased 3-year survival rate of 23% versus 11%. This was the first randomized cooperative group study demonstrating a survival advantage resulting from the use of induction chemotherapy in locoregionally advanced NSCLC. In a subsequent study, the administration of additional "posterior" chemotherapy was not found to be feasible because of early disease progression and toxicity, while the administration of induction chemotherapy followed by concomitant chemoradiotherapy was feasible; therefore, the latter approach was studied further in a randomized phase III setting. This study compared a standard of two cycles of cisplatin and vinblastine followed by radiotherapy with an experimental arm of cisplatin and vinblastine followed by radiotherapy and concomitant carboplatin. Accrual to this study has been completed and results are expected in the near future. In resectable stage III disease, studies have focused on the optimal sequencing of multimodality therapy. A randomized study comparing standard regional therapy with radiotherapy and surgery versus a previously piloted approach combining chemotherapy, surgery, and radiotherapy was closed prematurely due to poor accrual. The next generation of studies in stage III NSCLC will focus on the integration of new chemotherapy agents into the treatment armamentarium for NSCLC. A randomized phase II study investigating paclitaxel, gemcitabine, and vinorelbine in combination with cisplatin in the induction setting and as concomitant chemoradiotherapy has recently been activated.

Co-ordinated over-expression of the MRP and gamma-glutamylcysteine synthetase genes, but not MDR1, correlates with doxorubicin resistance in human malignant mesothelioma cell lines

While human malignant mesothelioma is extremely resistant to chemotherapy, its intrinsic resistance mechanisms remain largely unknown. In this study, we used normal human mesothelial cells and 5 human mesothelioma cell lines not previously exposed to chemotherapeutic agents to demonstrate that the mRNA for the multidrug resistance-associated protein (MRP) and gamma-glutamylcysteine synthetase (gamma-GCSh) heavy subunit genes, but not the P-glycoprotein (MDR1) gene, are co-ordinately over-expressed in mesothelioma cell lines. Expression of MRP as detected with an anti-MRP antibody correlated with decreased doxorubicin accumulation and resistance of mesothelioma cells to this drug. Our results strongly suggest roles for MRP and gamma-GCSh in chemoresistance in mesotheliomas.

Factors predictive of survival among 337 patients with mesothelioma treated between 1984 and 1994 by the Cancer and Leukemia Group B

PURPOSE

To examine the individual and joint effect of various pretreatment clinical characteristics on the survival of patients with mesothelioma treated by the Cancer and Leukemia Group B (CALGB).

PATIENTS AND METHODS

Between June 1984 and September 1994, 337 patients with malignant mesothelioma and no prior chemotherapy were accrued to seven phase II studies conducted by the CALGB which screened the efficacy of 10 treatment regimens or dose levels. The eligibility criteria for all studies were virtually identical. Patient characteristics include the following: age older than 60 years (63%); male (83%); performance status (PS) of 0 or 1 (81%); chest pain (60%); definite asbestos exposure (62%); >5% weight loss (41%); and pleural involvement (94%). Median survival time (MST) for the 10 treatment regimens ranged from 3.9 to 9.8 months (overall=7.2; 95% confidence interval [CI], 6.5 to 8.3), with 1-year survival between 14% and 50% (overall=27%; 95% CI, 23 to 33%).

RESULTS

Cox survival models and exponential regression trees were used to examine the prognostic importance of pretreatment patient characteristics. Univariate analyses show that patients with poor Eastern Cooperative Oncology Group PS, chest pain, dyspnea, platelet count (PLT) >400,000/microL, weight loss, serum lactate dehydrogenase (LDH) level >500 IU/L, pleural involvement, low hemoglobin (HGB) level, high WBC count, and increasing age over 75 years have a worse prognosis. With decreasing risk ratio, multivariate Cox analyses showed that pleural involvement, LDH >500 IU/L, poor PS, chest pain, PLT >400,000/microL, nonepithelial histology, and increasing age older than 75 years jointly predict poor survival. PS was the most important prognostic split in the regression tree. Terminal nodes were amalgamated to form six distinct prognostic subgroups with MST (2-year survival) of 13.9 (38%) in 36 patients, 9.5 (21%) in 36 patients, 9.2 (10%) in 146 patients, 6.5 (3%) in 33 patients, 4.4 (0%) in 73 patients, and 1.4 (0%) in 13 patients (p<0.0001).

CONCLUSIONS

The subgroup with the best survival (MST=13.9 months) included patients with PS=0 and age younger than 49 years, and patients with PS=0, age of 49 years or older, and HGB > or =14.6. The worst survival (MST= 1.4 months) occurred for patients with PS= 1/2 and WBC > or =15.6/microL.

Randomized trial of chemotherapy and radiation therapy with or without warfarin for limited-stage small-cell lung cancer: a Cancer and Leukemia Group B study

PURPOSE

Studies by the Veterans Administration Cooperative Studies Program and Cancer and Leukemia Group B (CALGB) suggested that the addition of warfarin to chemotherapy might enhance response and/or survival in small-cell lung cancer (SCLC). This randomized study evaluated the effect of warfarin with chemotherapy and radiation therapy in limited-stage SCLC.

PATIENTS AND METHODS

Patients were randomized to receive warfarin or no warfarin. All patients received three cycles of doxorubicin, cyclophosphamide, and etoposide (ACE). Cycles 4 and 5 (cisplatin, cyclophosphamide, and etoposide [PCE]) were given concurrently with radiation therapy. Three cycles of ACE were given after chemoradiation therapy, but were discontinued due to a high rate of pulmonary toxicity.

RESULTS

There were no significant differences in response rates, survival, failure-free survival, disease-free survival, or patterns of relapse between the warfarin-treated and control groups. In patients treated according to the initial design, an increase in failure-free survival seen with warfarin treatment approached significance (P = .07). Preamendment results, while not significant, did not have superimposable treatment survival curves. A landmark analysis at 8 months showed a median survival time after the landmark for complete responders of 33 months with warfarin treatment compared with < or = 13.75 months for complete or partial responders not treated with warfarin (P = .05). Differences between the complete responders in this preamendment population were not significant (P = .103).

CONCLUSION

Warfarin does not appear to improve outcome significantly in limited-stage SCLC. However, the differences in some variables between populations before the protocol amendment correspond to the favorable effects of anticoagulants observed in previous studies.

Yeast TAF(II)145 functions as a core promoter selectivity factor, not a general coactivator

In yeast, TATA box binding protein associated factors (TAF(II)s) are dispensable for transcription of most genes. Here we use differential display to identify a small subset of yeast genes whose transcription in vivo requires yTAF(II)145. Promoter-mapping studies reveal, unexpectedly, that the region of a gene that renders it yTAF(II)145-dependent is not the upstream activating sequence, which contains the activator-binding sites, but rather the core promoter. In fact, a core promoter requiring yTAF(II)145 retained that requirement when its transcription was directed by several unrelated upstream activating sequences and even in the absence of an activator. Taken together, our results indicate that yTAF(II)145 functions in recognition and selection of core promoters by a mechanism not involving upstream activators.