Asghar Naqvi

The Kinase Mirk/Dyrk1B Mediates Cell Survival in Pancreatic Ductal Adenocarcinoma

Ductal adenocarcinoma of the pancreas is almost uniformly lethal as this cancer is invariably detected at an advanced stage and is resistant to treatment. The serine/threonine kinase Mirk/Dyrk1B has been shown to be antiapoptotic in rhabdomyosarcomas. We have now investigated whether Mirk might mediate survival in another cancer in which Mirk is widely expressed, pancreatic ductal adenocarcinoma. Mirk was an active kinase in each pancreatic cancer cell line where it was detected. Mirk knockdown by RNA interference (RNAi) reduced the clonogenicity of Panc1 pancreatic cancer cells 4-fold and decreased tumor cell number, showing that Mirk mediates survival in these cells. Mirk knockdown by synthetic duplex RNAis in Panc1, AsPc1, and SU86.86 pancreatic cancer cells induced apoptosis and enhanced the apoptosis induced by gemcitibine. Mirk knockdown did not increase the abundance or activation of Akt. However, four of five pancreatic carcinoma cell lines exhibited either elevated Mirk activity or elevated Akt activity, suggesting that pancreatic cancer cells primarily rely on Mirk or Akt for survival signaling. Mirk protein was detected by immunohistochemistry in 25 of 28 cases (89%) of pancreatic ductal adenocarcinoma, with elevated expression in 11 cases (39%). Increased expression of Mirk was seen in pancreatic carcinomas compared with primary cultures of normal ductal epithelium by serial analysis of gene expression and by immunohistochemistry. Thus, Mirk is a survival factor for pancreatic ductal adenocarcinoma. Because knockout of Mirk does not cause embryonic lethality, Mirk is not essential for normal cell growth and may represent a novel therapeutic target. (Cancer Res 2006; 66(8): 4149-58)

Mirk/Dyrk1b Mediates Cell Survival in Rhabdomyosarcomas

Rhabdomyosarcoma is the most common sarcoma in children and is difficult to treat if the primary tumor is nonresectable or if the disease presents with metastases. The function of the serine/threonine kinase Mirk was investigated in this cancer. Mirk has both growth arrest and survival functions in terminally differentiating skeletal myoblasts. Maintenance of Mirk growth arrest properties would cause down-regulation of Mirk in transformed myoblasts. Alternatively, Mirk expression would be retained if rhabdomyosarcoma cells used Mirk survival capability. Mirk expression was significant in 12 of 16 clinical cases of rhabdomyosarcoma. Mirk was detected in each rhabdomyosarcoma cell line examined. Mirk was a functional kinase in each of three rhabdomyosarcoma cell lines, where it proved to be more active than in C2C12 skeletal myoblasts. Mirk mediated survival of the majority of clonogenic rhabdomyosarcoma cells. Knockdown of Mirk by RNA interference reduced the fraction of RD and of Rh30 rhabdomyosarcoma cells capable of colony formation 3- to 4-fold in multiple experiments. Depletion of Mirk induced cell death by apoptosis, as shown by increased numbers of terminal deoxynucleotidyl transferase-mediated nick-end labeling-positive cells and by increased binding of Annexin V. Mirk is a stress-activated kinase that mediates expression of contractile proteins in differentiating myoblasts, but Mirk is not essential for muscle formation in the embryo. It is likely that Mirk also facilitates survival of satellite cell-derived rhabdomyoblasts in regenerating skeletal muscle and aids their differentiation. This survival function is maintained in rhabdomyosarcoma, where Mirk may be a novel therapeutic target.

Calcium pyrophosphate dihydrate deposition disease (CPPD)/Pseudogout of the temporomandibular joint - FNA findings and microanalysis.

We report a case of a Calcium pyrophosphate dihydrate deposition disease (CPPD) presenting as a mass in the parotid and temporomandibular joint (TMJ) that simulated a parotid tumor. A 35 year-old man presented with pain in the left ear area. A CT Scan of the area showed a large, calcified mass surrounding the left condylar head, and extending into the infratemporal fossa. FNA of the mass showed birefringent crystals, most of which were rhomboid with occasional ones being needle shaped, embedded in an amorphous pink substance. Scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS) of these crystals showed peaks corresponding to calcium and phosphorus. SEM/EDS is a rapid method of diagnosing calcium pyrophosphate dihydrate deposition disease (CPPD) and an alternative to more commonly used method of special staining of cell block sections coupled with polarizing microscopy.

Predictive value of gadolinium enhancement in differentiating ALT/WD liposarcomas from benign fatty tumors

ObjectiveTo determine the predictive value of gadolinium enhancement on MRI in differentiating atypical lipomatous tumor (ALT)/well-differentiated (WD) liposarcoma from benign fatty tumors.DesignAll histologically proven fatty tumors with preoperative gadolinium-enhanced MRI were reviewed. Only those tumors with predominantly fatty signal were included. Sensitivity, specificity, and positive and negative predictive values for both gadolinium enhancement and biopsy as predictors for the final diagnosis of ALT/WD liposarcoma were calculated.PatientsFrom 129 patients evaluated for fatty tumors between 1994 and 2002, the patient population was narrowed to 32 excised fatty tumors with preoperative gadolinium-enhanced MRI.ResultsAs a predictor of ALT/WD liposarcoma, the presence of gadolinium enhancement showed 100% sensitivity, 71% specificity, 53% positive predictive value and 100% negative predictive value. Needle or incisional biopsy yielded 57% sensitivity, 100% specificity, 100% positive predictive value and 63% negative predictive value for a diagnosis of ALT/WD liposarcoma.ConclusionsGadolinium enhancement of a homogeneous fatty soft tissue tumor is a sensitive screening tool to determine possible diagnosis of ALT/WD liposarcoma. Biopsy, on the other hand, is specific but insensitive.

Decreased proliferation precedes growth factor changes after physeal irradiation.

The effects of irradiation on growth plate chondrocytes and mediators of chondrocytic differentiation are poorly understood. In earlier work on rat growth plate changes ½ to 4 weeks after irradiation, a nadir was identified at 1 week in proliferation and growth factor expression coincident with maximal histomorphometric derangement. The purpose of this study was to determine the earlier sequential relationship of proliferative, growth factor, and histomorphometric changes after irradiation leading to the 1-week nadir. Twenty-four weanling 5-week-old male Sprague-Dawley rats had right knee irradiation with single fraction 17.5 Gy whereas the left leg served as an internal control. The earliest change identified was a significant decrease in BrdU evidence of proliferative activity between 6 and 12 hours after irradiation, which persisted through 48 hours. Twelve to 24 hours after irradiation, caspase-3 staining for apoptosis was higher than that in growth plates not having received radiotherapy. Histomorphometric changes after irradiation were observed as early as 24 hours. Growth factors and their downstream antiapoptotic and proapoptotic mediators did not differ significantly between limbs through 48 hours. The current study suggests that decreased proliferation and apoptosis precede any change in histomorphometric features of the growth plate after irradiation and that decreased growth factor expression occurs later.

Combination Radioprotectors Maintain Proliferation Better than Single Agents by Decreasing Early Parathyroid Hormone-Related Protein Changes after Growth Plate Irradiation

Abstract Damron, T. A., Horton, J. A., Naqvi, A., Loomis, R. M., Margulies, B. S., Strauss, J. A., Farnum, C. E. and Spadaro, J. A. Combination Radioprotectors Maintain Proliferation Better than Single Agents by Decreasing Early Parathyroid Hormone-Related Protein Changes after Growth Plate Irradiation. Radiat. Res. 165, 350–358 (2006). Our hypothesis was that combinations of radioprotectors would be more effective than individual agents in minimizing the effects of radiation on the growth plate after single-fraction hind-limb irradiation of Sprague-Dawley rats. At 2 days postirradiation, the decrease in parathyroid hormone-related protein and parathyroid hormone receptor 1 expression in the irradiated growth plate transitional and hypertrophic zones was reversed in both of the combination groups but persisted in the groups treated with the individual drugs. By 2 weeks, positive findings unique to the combination-treatment animals included greater mean proliferation in the irradiated growth plate than on the contralateral side, smaller limb length discrepancies, reversal of the increased overall matrix area fraction, and reversal of the usual deficiency in Indian hedgehog staining in the irradiated hypertrophic zone. While all treatments had a positive effect in reversing the decrease in B-cell leukemia 2 protein and coincident increase in Bax previously observed 2 weeks postirradiation, the two combination groups had a more robust effect. Combinations of radioprotectors may achieve their beneficial additive effects in the growth plate by decreasing the usual early drop in parathyroid hormone-related protein and parathyroid hormone receptor 1 after irradiation, resulting in a cascade of parathyroid hormone-related protein-mediated events.

The spectrum of thrombotic thrombocytopenic purpura: a clinicopathologic demonstration of tacrolimus-induced thrombotic thrombocytopenic purpura in a lung transplant patient.

Immunosuppressive drugs used post-transplantation are among the most common causes of thrombotic thrombocytopenic purpura (TTP). Diagnosis is often confounded not only by its myriad presentations, but also because these manifestations may be explained by the comorbidities or complications of transplantation. A 61-year-old female who had a single lung transplant for severe chronic obstructive pulmonary disease maintained on corticosteroids, tacrolimus and mycophenolate mofetil, was admitted for fever, headache with confusion and lethargy. She was mildly anemic and thrombocytopenic. Peripheral smear showed rare fragmented red cells. Muddy brown casts were present on urinalysis. She was diagnosed with TTP. Tacrolimus was discontinued and the mental status of the patient, anemia and thrombocytopenia improved significantly.

Little-finger mass in a 29-year-old man.

A 29-year-old male patient presented with a slowly growing mass in his left little finger. Radiologic studies showed a soft tissue mass around the middle interphalangeal joint Trucut biopsy of the mass and a subsequent resection showed a neoplasm composed of inflammatory, myxoid, and hyalinized areas. Large atypical epithelioid cells with macronucleoli and abundant cytoplasm were seen against a background of lymphocytes, plasma cells, and sheets of eosinophils. The myxoid areas showed cords of cells in a loose background alternating with areas showing lipoblast-like cells. The variegated light microscopic appearance, coupled with the cytologic features of the atypical epithelioid cells, is key to the diagnosis of myxoinflammatory fibroblastic sarcoma. This entity must be considered whenever a myxoid or inflammatory mesenchymal lesion is encountered in the distal extremities.