Upregulation of MMP-2 by HMGA1 promotes transformation in undifferentiated, large-cell lung cancer

Although lung cancer is the leading cause of cancer death worldwide, the precise molecular mechanisms that give rise to lung cancer are incompletely understood. Here, we show that HMGA1 is an important oncogene that drives transformation in undifferentiated, large-cell carcinoma. First, we show that the HMGA1 gene is overexpressed in lung cancer cell lines and primary human lung tumors. Forced overexpression of HMGA1 induces a transformed phenotype with anchorage-independent cell growth in cultured lung cells derived from normal tissue. Conversely, inhibiting HMGA1 expression blocks anchorage-independent cell growth in the H1299 metastatic, undifferentiated, large-cell human lung carcinoma cells. We also show that the matrix metalloproteinase-2 (MMP-2) gene is a downstream target upregulated by HMGA1 in large-cell carcinoma cells. In chromatin immunoprecipitation experiments, HMGA1 binds directly to the MMP-2 promoter in vivo in large-cell lung cancer cells, but not in squamous cell carcinoma cells. In large-cell carcinoma cell lines, there is a significant, positive correlation between HMGA1 and MMP-2 mRNA. Moreover, interfering with MMP-2 expression blocks anchorage-independent cell growth in H1299 large-cell carcinoma cells, indicating that the HMGA1-MMP-2 pathway is required for this transformation phenotype in these cells. Blocking MMP-2 expression also inhibits migration and invasion in the H1299 large-cell carcinoma cells. Our findings suggest an important role for MMP-2 in transformation mediated by HMGA1 in large-cell, undifferentiated lung carcinoma and support the development of strategies to target this pathway in selected tumors.

The High-Mobility Group A1 Gene Up-Regulates Cyclooxygenase 2 Expression in Uterine Tumorigenesis

Uterine cancer is the most common cancer of the female genital tract and is the fourth most frequent cause of cancer death in women in the U.S. Despite the high prevalence of uterine cancers, the molecular events that lead to neoplastic transformation in the uterus are poorly understood. Moreover, there are limited mouse models to study these malignancies. We generated transgenic mice with high-mobility group A1 gene (HMGA1a) expression targeted to uterine tissue and all female mice developed tumors by 9 months of age. Histopathologically, the tumors resemble human uterine adenosarcoma and are transplantable. To determine whether these findings are relevant to human disease, we evaluated primary human uterine neoplasms and found that HMGA1a mRNA and protein levels are increased in most high-grade neoplasms but not in normal uterine tissue, benign tumors, or most low-grade neoplasms. We also found that HMGA1a up-regulates cyclooxygenase 2 (COX-2) expression in transgenic tumors. Moreover, both HMGA1a and COX-2 expression are up-regulated in high-grade human leiomyosarcomas. Using chromatin immunoprecipitation, HMGA1a binds directly to the COX-2 promoter in human uterine cancer cells in vivo and activates its expression in transfection experiments. We also show that blocking either HMGA1a or COX-2 in high-grade human uterine cancer cells blocks anchorage-independent cell growth in methylcellulose. These findings show that HMGA1a functions as an oncogene when overexpressed in the uterus and contributes to the pathogenesis of human uterine cancer by activating COX-2 expression. Although a larger study is needed to confirm these results, HMGA1a may be a useful marker for aggressive human uterine cancers.

Early steroid withdrawal therapy in renal transplant recipients: a steroid-free sirolimus and CellCept-based calcineurin inhibitor-minimization protocol

BACKGROUND

Maintenance steroid therapy is associated with significant morbidity and mortality in renal transplant recipients. Elimination of the many long-term side effects of corticosteroids, including those that impinge on cardiovascular risk, remains a laudable goal in designing immunosuppressive protocols. However, concern persists that prednisone-free maintenance immunotherapy in kidney transplant recipients will result in an increase incidence of acute rejections, renal dysfunction and ultimate graft loss.

METHODS

From 24 March 2003 to 1 December 2004, 84 kidney transplant recipients (61 deceased donor, 23 living donors) discontinued prednisone on post-operative day 6. Immunotherapy consisted of polyclonal antibody induction (thymoglobulin) for five d and prednisone intraoperatively with a rapid taper over the next six d. Maintenance therapy consisted of a sirolimus and CellCept-based calcineurin inhibitor-minimization protocol. Tacrolimus and mycophenolate mofetil (CellCept) were initiated on day 0. Sirolimus immunotherpay was started on post-operative day 6 concomitant with the cessation of steroids. We compared outcomes with that of our historical controls, treated with sirolimus and tacrolimus, who did not discontinue steroids. In addition, we analyzed outcomes independently for recipients of living and deceased donors in the steroid-free protocol.

RESULTS

The recipients on prednisone-free maintenance immunosuppression had excellent 2.5-yr actuarial patient survival (97%), graft survival (93%), and acceptable acute rejection-free graft survival (89%). The mean serum creatinine level (+/-SD) at one yr was 1.5 +/- 0.6 mg/dL and at two yr was 1.5 +/- 0.6 mg/dL. We noted that 5% of recipients developed cytomegalovirus (CMV) syndrome; 1%, polyoma nephropathy; 1%, post-transplant lymphoproliferative disorder (PTLD), and 5% developed post-transplant diabetes mellitus (PTDM). In all, 91% of kidney recipients with functioning grafts remain steroid-free as of 31 December 2005. When compared with historical controls, the recipients on the early steroid-withdrawal (ESW) protocol had comparable graft survival, acute rejection-free survival, graft function, but significantly better patient actuarial survival (p = 0.048). In addition, recipients on the steroid-free protocol had decreased prevalence of four risk factors for cardiovascular disease when compared with historical controls: hypertension (p = 0.008), hyperlipidemia (p = 0.003), weight gain (p = 0.024), and incidence of PTDM (p = 0.015).

CONCLUSION

Early steroid-withdrawal in renal transplant recipients with a sirolimus and CellCept-based calcineurin inhibitor-minimimization protocol can effectively reduce many of the steroid-related side effects, decrease risk factors for cardiovascular disease, and is associated with improved recipient survival without compromising graft function.

Inactivation of the Cdkn2a locus cooperates with HMGA1 to drive T-cell leukemogenesis

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive leukemia with high relapse rates compared to B-lineage ALL. We previously showed that HMGA1a transgenic mice develop aggressive T-ALL, indicating that HMGA1 causes leukemic transformation in vivo. HMGA1 is also highly expressed in embryonic stem cells, hematopoietic stem cells and diverse, refractory human cancers. Disruption of the CDKN2A tumor suppressor locus occurs in most cases of T-ALL and is thought to contribute to leukemic transformation. To determine whether loss of function of CDKN2A cooperates with HMGA1 in T-ALL, we crossed HMGA1a transgenics onto a Cdkn2a null background. We discovered that T-ALL is markedly accelerated in HMGA1a transgenic Cdkn2a null mice. In addition, these mice recapitulate salient clinical and pathologic features of human T-ALL. HMGA1 is also highly overexpressed in human T-ALL. These findings suggest that HMGA1 plays a causative role in T-ALL and could represent a rational therapeutic target.

Mismatch repair gene mutations in renal cell carcinoma

We investigated the spectrum and genetic basis for mismatch repair (MMR) deficiency in renal cell carcinoma (RCC) by examining expression of four MMR genes important for hereditary and sporadic carcinogenesis. MMR deficiency was assessed using microsatellite instability (MSI) and genetic analyses of 25 cell lines derived from renal tumors. MMR gene alterations were detected using reverse transcription of RNA coupled with polymerase chain reaction (RT-PCR) and DNA sequencing. Three RCC lines with undetectable MLH1 were identified and investigated for MSI and inactivating mutations in the hMLH1 MMR gene. Genetic instability and hMLH1 mutations were identified in two RCC lines and their corresponding tumors. Genetic alterations affecting expression were limited to MLH1 since other MMR proteins (MSH2, MSH6 and PMS2) were detectable in our RCC lines. Complete inactivation of MMR is apparently uncommon in RCC and occurs predominantly through inactivating mutations in the hMLH1 gene.

Monthly screening for polyoma virus eliminates BK nephropathy and preserves renal function

BACKGROUND

Polyoma BK virus nephropathy is a serious complication after renal transplantation and is associated with a high rate of allograft failure. Progressive infection with BK virus in immunocompromised renal transplant recipients occurs in detectable stages: Viruria, viremia, then nephropathy.

METHODS

In January, 2006, we initiated a plasma screening policy for all new transplant recipients, with monthly blood testing for BK virus by polymerase chain reaction (PCR). Between January 1, 2006, and February 28, 2007, 66 renal transplants were performed at our center. The 11 patients with a positive plasma BK PCR test underwent prompt reduction in baseline immunotherapy consisting of a 50% daily dose reduction (n = 6) or complete discontinuation of therapy with mycophenolate mofetil (n = 5).

RESULTS

After reduction or discontinuation of mycophenolate mofetil, 10 patients became negative for BK virus in the plasma within 6 months. Progression to BK nephropathy has not occurred, and renal transplant dysfunction secondary to acute cellular rejection developed in only 1 patient (9%). One year post-transplant, the mean serum creatinine values for these 11 patients remained stable at 1.5 mg/dL.

CONCLUSION

Monthly plasma screening for BK virus by PCR together with immunosuppressive regimen reduction prevents BK nephropathy. In addition, this intensive screening protocol is associated with a low rate of acute rejection and excellent preservation of renal function.