When to sweat: A history of chemotherapy in malignant sweat gland tumors. A unique case report and literature review

Sarcomatoid sweat gland carcinomas are rare among cutaneous cancers, with less than 20 cases described. A 54-year-old woman with sarcomatoid sweat gland carcinoma of the right upper extremity suffered extensive recurrence at 15 months, unresponsive to chemotherapy. There is no standard treatment or chemotherapy regimens for metastatic sweat gland carcinoma.

Sarcomatoid Eccrine Porocarcinoma in a Patient with Urothelial Carcinoma

Introduction/Objective

Sarcomatoid porocarcinoma of skin is an exceedingly rare and diagnostically challenging malignancy of the sweat gland. In this report, we describe a rare case of a sarcomatoid eccrine porocarcinoma initially diagnosed to be a squamous cell carcinoma (SCC) in a patient with metastatic urothelial carcinoma (UC).

Methods/Case Report

Our patient is a 60 year old male with stage IV, poorly differentiated UC status post TURBT with residual tumor, and a 4 x 3 x 1 cm, polypoid, ulcerating skin nodule on his right cheek presumptively diagnosed to be an SCC on biopsy at an outside hospital. Given the concern that this cutaneous lesion may be a metastatic UC with squamous differentiation, the skin nodule was re-biopsied at our hospital. On histology, the lesion consisted of sheets of squamoid, polygonal cells in the dermis with pleomorphic nuclei showing irregular contours, prominent nucleoli, coarse chromatin, and frequent mitoses. The tumor was focally connected to the epidermis, which established it as a primary skin neoplasm and not a metastatic lesion. The tumor cells stained diffusely positive for vimentin, AE1/AE3, CK5/6, HMW CK, CK7, p63, and p16, negative for CK20, GATA-3, BerEP4, and Sox10, and showed high Ki67 proliferation index. Within the tumor sheets were poorly formed, focal ductal elements that stained positive for CAM5.2, EMA, CEA, and CK19, and negative for p63. The tumor showed comedo necrosis, epidermal ulceration, and no keratinization. The tumor was diagnosed to be a porocarcinoma given its positive staining for CK7 and p16, presence of focal ductal elements, and epidermal connection, with sarcomatoid features indicated by strong vimentin expression.

Results (if a Case Study enter NA)

NA.

Conclusion

In this report, we described an exceedingly rare, diagnostically challenging case of a sarcomatoid porocarcinoma initially suspected to be a cutaneous SCC or metastatic UC with squamous differentiation. Although the tumor cells morphologically resembled SCC, its positive staining for CK7 and p16, presence of ductal elements, and lack of keratinization, favored a diagnosis of porocarcinoma rather than cutaneous SCC. Its focal connection to the epidermis and lack of GATA-3 expression favored a primary skin neoplasm rather than a metastatic UC. Its sarcomatoid nature was indicated by strong vimentin expression. Sarcomatoid porocarcinoma is diagnostically challenging given its rarity and potential to mimic other cutaneous malignancies such as SCC.

Metastasis of a Primary Sinonasal Alveolar Rhabdomyosarcoma to the Testicle in an Adult Patient

Introduction/Objective

Alveolar rhabdomyosarcoma is an aggressive tumor of skeletal muscle differentiation that predominantly affects adolescents and young adults, and is rare over 45 years of age. It has poor prognosis with metastasis, and most commonly spreads to the lymph nodes, bone marrow, and lungs. In this report, we describe a middle-aged patient with a primary sinonasal alveolar rhabdomyosarcoma which metastasized to the right testicle, an unusual metastatic site reported only a few times in literature.

Methods/Case Report

Our patient is a 53 year old male who presented in 2020 with recurrent epistaxis and bilateral cervical lymphadenopathy over a 2 month period. Maxillofacial CT/MRI imaging revealed a 4-cm sized mass within the left nasal cavity eroding into the ethmoid sinuses. The patient underwent endoscopic sinus surgery of the sinonasal mass, which on histology, appeared as poorly differentiated small round blue cells with numerous mitoses infiltrating as single cells and nests. These cells stained positive for vimentin, myogenin, desmin, and CD56, and negative for AE1/AE3, chromogranin, S-100, CD99, and CD45. The cells showed very high Ki67 proliferation index (70-80%) and tested positive for FOXO1 gene rearrangement, which supported the diagnosis of alveolar rhabdomyosarcoma. The patient completed chemoradiation therapy, and MRI scans over the next 2 years were negative for residual sinonasal tumor. However, the patient returned in 2022 after having undergone a right orchiectomy at an outside hospital for testicular pain, and abdominal CT showed diffuse retroperitoneal lymphadenopathy concerning for metastasis. On histology, the resected testicle showed seminiferous tubules infiltrated and destroyed by sheets of poorly differentiated small round blue cells with fibrous septae separating the nests of tumor cells into alveolar-like spaces with central loss of cohesion. The tumor cells showed the same immunohistochemical staining pattern as the primary sinonasal lesion, thus confirming it to be metastatic alveolar rhabdomyosarcoma.

Results (if a Case Study enter NA)

NA.

Conclusion

It is unusual for alveolar rhabdomyosarcomas to occur in adults over 45 years old, and is even rarer for these tumors to metastasize to the testicle. Metastases also only account for 1% of testicular tumors. Our report documents a very rare case of an alveolar rhabdomyosarcoma in a middle-aged adult which metastasized to the testicle after chemoradiation therapy.

Two Cases of Duodenal Neuroendocrine (Carcinoid) Tumor Concurrent with Invasive Gastric Adenocarcinoma and Pancreatic Intraductal Papillary Mucinous Neoplasm

Introduction/Objective

Neuroendocrine (carcinoid) tumors of the duodenum are extremely rare and account for only 2-4% of gastrointestinal tract neuroendocrine tumors. We report two cases of incidentally discovered duodenal neuroendocrine tumor which respectively occurred in a patient with invasive gastric adenocarcinoma and in a patient with pancreatic intraductal papillary mucinous neoplasm (IPMN).

Methods/Case Report

The first case involved a 60-year old male who presented with melena and symptomatic anemia and was found on EGD to have a large circumferential mass at the gastric antrum/pylorus, which was revealed to be an invasive gastric adenocarcinoma on biopsy. At the time of distal gastrectomy for this malignancy, a concurrent, 0.6 cm-sized, low grade neuroendocrine tumor was incidentally discovered at the duodenal margin. The duodenal tumor consisted of nests and trabeculae of monotonous cells with ovoid/round nuclei, finely speckled “salt and pepper” chromatin, and low mitotic rate (< 2 mitoses/2 mm2), and invaded only into submucosa. The tumor cells were strongly and diffusely positive for neuroendocrine markers chromogranin, synaptophysin, and CD56, positive for CK7 and CDX2, negative for CK20, and with low Ki67 proliferation index (< 3%). The second case involved a 69-year old female who presented with epigastric pain and was found on abdominal CT to have a 4 cm-sized cystic mass in the pancreatic head. While biopsy of the pancreatic mass revealed an IPMN, a separate biopsy of an incidentally discovered, 1 cm-deep ulcer in the duodenum bulb revealed a low-grade neuroendocrine tumor with similar morphologic features, mitotic rate, and immunohistochemical staining pattern as the prior case while also negative for IMP3 stain. The patient had normal serum gastrin and urine HIAA levels, but elevated serum chromogranin-A levels.

Results (if a Case Study enter NA)

NA.

Conclusion

Duodenal carcinoids are rare (1-3% of primary duodenal tumors) and are mostly non-functional and unifocal. The duodenum is also the least common site (2-4%) for GI tract neuroendocrine tumors. The pathophysiology of these tumors is still poorly understood, with the majority occurring sporadically and a minority in the setting of hereditary cancer syndromes. This report documents two very rare instances of duodenal neuroendocrine tumor incidentally discovered with invasive gastric adenocarcinoma and pancreatic IPMN.

Biphasic Sarcomatoid Sweat Gland Carcinoma With Ductal Epithelial And Spindled Myoepithelial Cell Components (Malignant Mixed Tumor Of Skin)

Introduction/Objective

Sweat gland carcinomas are a group of malignant skin adnexal tumors that are difficult to diagnose due to their rarity, wide morphologic variation, and limited literature on diagnosis and classification. These tumors may appear bland and morphologically resemble benign skin adnexal tumors, or may appear poorly differentiated and mimic metastatic carcinoma especially from a breast primary. Biphasic sweat gland carcinomas are an even rarer entity, with only few cases reported in literature, and have been described to consist of a well- differentiated ductal epithelial component and a poorly differentiated, sarcomatoid, spindle cell component.

Methods/Case Report

Our case report describes a 53 year old female referred to our institution for diagnosis of an excised skin lesion of the right upper arm, which had been slowly growing for 8 years. The histology revealed a biphasic malignant neoplasm involving the dermis and subcutis. The tumor consisted of an epithelial cell component with glandular and squamoid morphology and positive for CK5/6, CK7, and CAM5.2, and a spindled myoepithelial cell component with sarcomatoid morphology and positive for S100, vimentin, and p63. Stains for CK20, ER, PR, PAX8, CEA, and TTF1 were negative. The histological and clinical findings favored a primary skin adnexal tumor, rather than a metastatic lesion.

The patient underwent wide local excision of the lesion given that margins of the original excision were indeterminate. The histology of this re-excision demonstrated the same biphasic tumor with ductal epithelial and sarcomatoid myoepithelial cell components positive for the same stains. Although margins were negative in this re-excision, 3-4 months later, the patient developed dyspnea with multiple new pulmonary and hilar masses discovered on imaging, and new-onset headache with a frontal lobe mass discovered on brain imaging. These masses were biopsied/resected, and revealed to be metastases of the original cutaneous tumor positive for the same markers.

Results (if a Case Study enter NA)

NA

Conclusion

This case report describes a rare, diagnostically challenging case of a biphasic sweat gland carcinoma with ductal epithelial and sarcomatoid myoepithelial cell components, which demonstrated aggressive behavior with distant metastasis. These tumors are a clinicopathological quandary given their rarity and the paucity of literature on their characterization.

Osciladores Caóticos implementados en Microcontrolador PIC18F

Introducción: Recientemente, los sistemas caóticos han llamado la atención de la comunidad científica internacional, debido a sus potenciales aplicaciones en varias ramas de la ciencia e ingeniería. Se han propuesto muchos trabajos con el fin de resolver algunos problemas interesantes, como la determinación de daños estructurales en los materiales o en sistemas de comunicaciones seguras. Sin embargo, la mayoría de estos trabajos se enfocan en sistemas caóticos en tiempo continuo, mientras que en muchos casos, es deseable que estos sistemas estén en el modo de tiempo discreto y puedan ser utilizados en tiempo real.                      Método: El presente trabajo propone la implementación experimental de tres osciladores caóticos discretizados en un microcontrolador simple. Los osciladores caóticos a implementar son muy conocidos y muy utilizados para ejemplificar posibles soluciones a diversos problemas: los osciladores de Lorenz, Rössler y Chen. Para lo cual, se utilizan tan solo un microcontrolador de bajo costo, unos cuantos resistores y un algoritmo de computación sencillo.Resultados: Se obtiene un sistema embebido de bajo costo y sencillo para implementar osciladores caóticos discretizados.                     Discusión o Conclusión: Se demuestra que los osciladores caóticos de Lorenz, Rössler y Chen pueden implementarse en cualquier microcontrolador de arquitectura basada en palabras de 18 bits o más. Además, se observa que el algoritmo propuesto se pude migrar de un oscilador a otro con solo sustituir el sistema caótico de ecuaciones.

Identification and analysis of murine pancreatic islet enhancers

AIMS/HYPOTHESIS

The paucity of information on the epigenetic barriers that are blocking reprogramming protocols, and on what makes a beta cell unique, has hampered efforts to develop novel beta cell sources. Here, we aimed to identify enhancers in pancreatic islets, to understand their developmental ontologies, and to identify enhancers unique to islets to increase our understanding of islet-specific gene expression.

METHODS

We combined H3K4me1-based nucleosome predictions with pancreatic and duodenal homeobox 1 (PDX1), neurogenic differentiation 1 (NEUROD1), v-Maf musculoaponeurotic fibrosarcoma oncogene family, protein A (MAFA) and forkhead box A2 (FOXA2) occupancy data to identify enhancers in mouse islets.

RESULTS

We identified 22,223 putative enhancer loci in in vivo mouse islets. Our validation experiments suggest that nearly half of these loci are active in regulating islet gene expression, with the remaining regions probably poised for activity. We showed that these loci have at least nine developmental ontologies, and that islet enhancers predominately acquire H3K4me1 during differentiation. We next discriminated 1,799 enhancers unique to islets and showed that these islet-specific enhancers have reduced association with annotated genes, and identified a subset that are instead associated with novel islet-specific long non-coding RNAs (lncRNAs).

CONCLUSIONS/INTERPRETATIONS

Our results indicate that genes with islet-specific expression and function tend to have enhancers devoid of histone methylation marks or, less often, that are bivalent or repressed, in embryonic stem cells and liver. Further, we identify a subset of enhancers unique to islets that are associated with novel islet-specific genes and lncRNAs. We anticipate that these data will facilitate the development of novel sources of functional beta cell mass.

Ba2YCu3O6.9 Powder Preparation by Sol-Gel Emulsion Techniques

Barium yttrium cuprate powders were prepared by a sol-gel emulsion process in which an aqueous nitrate solution containing Ba, Y, and Cu in the correct stoichiometry was emulsified in heptane. The resulting micrometer-sized droplets were gelled by adding a high-molecular-weight primary amine that extracts nitric acid from the aqueous phase and raises the pH of the droplets. Thermal gravimetric analysis revealed that the correct overall stoichiometry was obtained at temperatures lower than 400 °C during calcination, but X-ray diffraction showed that calcination at temperatures greater than 800° may be required to produce the correct phase. One possible advantage of this technique is the control of powder morphology on a micrometer scale so that powders can be prepared for advanced ceramics processing methods. Also, segregation of components, if any, will be restricted to distances less than one micrometer.

Effects of a p38 MAP kinase inhibitor on bone ingrowth and tissue differentiation in rabbit chambers

The effects of an oral p38 mitogen-activated protein kinase (MAPK) inhibitor and polyethylene particles separately and together on tissue differentiation in the bone harvest chamber (BHC) in rabbits over a 3-week treatment period were investigated. The harvested tissue was analyzed histomorphometrically for markers of bone formation (percentage of bone area), osteoblasts (alkaline phosphatase staining), and osteoclasts (CD51, the alpha chain of the vitronectin receptor). Polyethylene particles decreased the percentage of bone ingrowth and staining for alkaline phosphatase. The p38 MAPK inhibitor alone decreased alkaline phosphatase staining. When the oral p38 MAPK inhibitor was given and the chamber contained polyethylene particles, there was a suppression of bone ingrowth and alkaline phosphatase staining. In contrast to oral non-steroidal anti-inflammatory drugs (NSAIDs) and local Interleukin-1 receptor antagonist (IL-1ra) administration, the oral p38 MAPK inhibitor alone did not suppress bone formation when given during the initial phase of tissue differentiation. Particle-induced inflammation and the foreign body reaction were not curtailed when the p38 MAPK inhibitor was given simultaneously with particles. Additional experiments are needed to establish the efficacy of p38 MAPK inhibitor administration on mitigating an established inflammatory and foreign body reaction that parallels the clinical situation more closely.

Renin-angiotensin system blockade in biopsy-proven allograft nephropathy

Allograft nephropathy leads to progressive renal injury and ultimate graft loss. In native kidney disease, the use of angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) is beneficial in retarding the decline of renal function. We reviewed a cohort of renal transplant recipients who were prescribed either an ACEi or ARB for biopsy-proven allograft nephropathy. Patients were followed from time of initiation of ACEi/ARB and were stratified based on biopsy findings. Outcomes of interest included safety, allograft survival, renal function, and rate of renal function decline pre- and post-ACEi/ARB. The 5-year allograft survival after biopsy was 83%. Mean serum creatinine was 2.2 +/- 1.1 mg/dL (range 1.0 to 4.3) at time of biopsy and 2.6 +/- 1.2 mg/dL (1.2 to 6.5) at last follow-up. The mean slope of the creatinine versus time (SD) was 2.43 (7.93) in the 12 months prior to therapy and 1.45 (3.66) following therapy, with the absolute difference in slope -3.38 (6.06) (P =.0004). We conclude that treatment with ACEi/ARB is beneficial in the management of allograft nephropathy.

Regulation of the Expression of the Prostate-specific Antigen by Claudin-7

Claudins are a family of proteins involved in forming tight junctions between cells. Here we describe two forms of claudin-7 (CLDN-7), a full-length form of CLDN-7 with 211 amino-acid residues and a C-terminal truncated form with 158 amino-acid residues. These two forms of CLDN-7 are able to regulate the expression of a tissue-specific protein, the prostate-specific antigen (PSA), in the LNCaP prostate cancer cell line. We also found that the expression of CLDN-7 is responsive to androgen stimulation in the LNCaP cell line, suggesting that this protein is involved in the regulatory mechanism of androgen. Both forms of claudin-7 are expressed in human prostate, kidney and lung samples, and in most samples, the full-length form of claudin-7 was predominant. However, in some prostate samples from healthy individuals, the truncated form of claudin-7 is predominantly expressed. Our results demonstrated that unlike other claudins, CLDN-7 has both structural and regulatory functions, and the two forms of CLDN-7 may be related to cell differentiation in organ development.

Autologous chondrocyte implantation

Rationale for the treatment of cartilage damage in younger patients depends on a thorough understanding of the predisposing factors for the chondrosis and the stage of disease. Implantation with autologous cultured chondrocytes allows for resurfacing of larger defect areas with reproducibly good/excellent results in 90% of patients with isolated lesions of the femoral condyle. Patellar lesions also may be successfully treated (approximately 75% improved) but strict attention must be given to correction of malalignment. Results in patients with tibial and salvage lesions are encouraging; however, these results should be viewed with caution due to the small number of patients with 2-year follow-up. Autologous chondrocyte implantation involves an open technique with the inherent disadvantages of adhesions and a more prolonged recovery. However, these disadvantages must be weighed against the procedure's ability to produce a hyaline-type tissue with greater durability than fibrocartilage repairs produced by traditional marrow-stimulation techniques. We recommended matching the treatment procedure to patient expectations and lesion/demographic characteristics. Based on the available literature. algorithms have been published that recommend autologous chondrocyte implantation be reserved as first-line treatment for high-demand patients with large lesions (>2 cm2) and as revision therapy in patients with lesions of all sizes, regardless of patient demand, who have failed alternative marrow stimulation techniques.

Avian retrovirus DNA internal attachment site requirements for full-site integration in vitro

Concerted integration of retrovirus DNA termini into the host chromosome in vivo requires specific interactions between the cis-acting attachment (att) sites at the viral termini and the viral integrase (IN) in trans. In this study, reconstruction experiments with purified avian myeloblastosis virus (AMV) IN and retrovirus-like donor substrates containing wild-type and mutant termini were performed to map the internal att DNA sequence requirements for concerted integration, here termed full-site integration. The avian retrovirus mutations were modeled after internal att site mutations studied at the in vivo level with human immunodeficiency virus type 1 (HIV-1) and murine leukemia virus (MLV). Systematic overlapping 4-bp deletions starting at nucleotide positions 7, 8, and 9 in the U3 terminus had a decreasing detrimental gradient effect on full-site integration, while more internal 4-bp deletions had little or no effect. This decreasing detrimental gradient effect was measured by the ability of mutant U3 ends to interact with wild-type U3 ends for full-site integration in trans. Modification of the highly conserved C at position 7 on the catalytic strand to either A or T resulted in the same severe decrease in full-site integration as the 4-bp deletion starting at this position. These studies suggest that nucleotide position 7 is crucial for interactions near the active site of IN for integration activity and for communication in trans between ends bound by IN for full-site integration. The ability of AMV IN to interact with internal att sequences to mediate full-site integration in vitro is similar to the internal att site requirements observed with MLV and HIV-1 in vivo and with their preintegration complexes in vitro.

12-O-tetradecanoylphorbol-13-acetate (TPA)-induced c-Jun N-terminal kinase (JNK) phosphatase renders immortalized or transformed epithelial cells refractory to TPA-inducible JNK activity

c-Jun N-terminal kinase (JNK) regulates gene expression in response to various extracellular stimuli. JNK can be activated by the tumor promoting agent, 12-O-tetradecanoylphorbol-13-acetate (TPA) in normal human oral keratinocytes but not in human keratinocytes that have been immortalized (HOK-16B and HaCaT) or transformed (HOK-16B-Bap-T) nor in a cervical carcinoma cell line (HeLa). The refractory JNK activation response to TPA is not due a defect in the JNK pathway, because JNK can be activated by other stimuli, e.g. UV irradiation and an alkylating agent N-methyl-N'-nitrosoguanidine in these immortalized or transformed cells. More importantly, the refractory JNK and JNKK activation response to TPA can be restored by treatment of the cells with a combination of TPA and a protein-tyrosine phosphatase inhibitor, sodium orthovanadate. Furthermore, pretreatment of cells with TPA partially inhibited UV- or N-methyl-N'-nitrosoguanidine-induced JNK activity. These results suggest that a TPA-inducible, orthovanadate-sensitive protein-tyrosine phosphatase may specifically down-regulate JNK signaling pathway in these immortalized/transformed epithelial cells. In contrast, ERK and p38/Mpk2 are not regulated by this TPA-induced phosphatase. This putative protein-tyrosine phosphatase appears to be JNK pathway-specific.

ATF-2 has intrinsic histone acetyltransferase activity which is modulated by phosphorylation

Transcription factors carry functional domains, which are often physically distinct, for sequence-specific DNA binding, transcriptional activation and regulatory functions. The transcription factor ATF-2 is a DNA-binding protein that binds to cyclic AMP-response elements (CREs), forms a homodimer or heterodimer with c-Jun, and stimulates CRE-dependent transcription. Here we report that ATF-2 is a histone acetyltransferase (HAT), which specifically acetylates histones H2B and H4 in vitro. Motif A, which is located in the HAT domain, is responsible for the stimulation of CRE-dependent transcription; moreover, in response to ultraviolet irradiation, phosphorylation of ATF-2 is accompanied by enhanced HAT activity of ATF-2 and CRE-dependent transcription. These results indicate that phosphorylation of ATF-2 controls its intrinsic HAT activity and its action on CRE-dependent transcription. ATF-2 may represent a new class of sequence-specific factors, which are able to activate transcription by direct effects on chromatin components.

The E7 oncoprotein of human papillomavirus type 16 interacts with F-actin in vitro and in vivo

We report here that E7 oncoprotein of human papillomavirus type 16 (HPV-16) forms a complex in vivo and in vitro with actin, one of the components of the cellular cytoskeleton. The in vivo interaction was detected by immunofluorescent staining and confocal microscopic examination of normal human oral keratinocytes (NHOK) and CV-1 cells after transient expression of E7 employing the vaccinia virus-T7 RNA polymerase system and by coimmunoprecipitation from an immortalized, nontumorigenic cell line obtained after transfecting NHOK with the cloned HPV-16 DNA genome. The in vitro interaction was detected by cosedimentation of bacterially expressed E7 phosphorylated with rabbit reticulocyte lysate or purified casein kinase II (CKII) prior to incubation with F-actin. This interaction was inhibited if E7 phosphorylation by the rabbit reticulocyte lysate was prevented with heparin, a CKII inhibitor, or if the amino acids Ser-31 and Ser-32 in E7, which are phosphorylated by CKII, were replaced with amino acids that cannot be phosphorylated. Interestingly, a decrease in the amount of polymerized actin occurred in cells expressing E7.

Residual bladder dysfunction 2 to 10 years after acute transverse myelitis

OBJECTIVE

Acute transverse myelitis (ATM) is a relatively rare condition in children. The recovery rate is reported to be generally complete. In the current study, the long-term urological outcome of children with ATM was assessed.

METHODOLOGY

The medical records of children with ATM admitted to Queen Mary Hospital, Hong Kong, over the last 15 years, were reviewed.

RESULTS

The median age of the five children with ATM at the time of onset was 6 years (range = 2-12 years). The median length of follow up was 5 years (2-10 years). Four children recovered completely from paraparesis; two had no urinary symptoms with normal micturition. However, video-urodynamic studies 3 years after the acute onset revealed that four out of the five children, including one without any urinary symptom, suffered from residual bladder dysfunction - two from contractile neurogenic bladder and two from intermediate type of neurogenic bladder.

CONCLUSION

Residual bladder dysfunction is common in children suffering from ATM despite improvement of paraparesis and apparent lack of urological symptoms. Long-term follow up of urological function in these patients is recommended.

Retrovirus DNA termini bound by integrase communicate in trans for full-site integration in vitro

Integration of linear retrovirus DNA involves the concerted insertion of the viral termini (full-site integration) into the host chromosome. We investigated the interactions that occur between long terminal repeat (LTR) termini bound by avian retrovirus integrase (IN) for full-site integration in vitro. Wild-type (wt) or mutant LTR donors that possess gain-of-function ("G") or loss-of-function ("L") for full-site integration activity were used. G LTR termini are characterized as having significantly higher strand transfer activity than the wt and the L LTR termini. L LTR mutations are classified as partially or extremely defective for strand transfer activity. The L mutations were further classified by their ability to either permit or block the assembly of G or wt LTR termini into nucleoprotein complexes capable of full-site strand transfer. We demonstrated that avian myeloblastosis virus IN bound to G LTR termini increased the incorporation of partially defective L LTR termini into nucleoprotein complexes that were capable of full-site integration. The observed full-site integration activity of these assembled nucleoprotein complexes appeared to be influenced by each individual IN-LTR complex in trans. In contrast, extremely defective L LTR termini exhibited the ability to effectively block the assembly of wt LTR termini into nucleoprotein complexes capable of full-site strand transfer. Data from nonspecific DNA competition experiments suggested that IN had an apparent higher affinity for G LTR donor termini than for partially defective L LTR donor termini as measured by full-site integration activity. However, assembled nucleoprotein complexes containing either two G or two L LTR donors were stable, having a similar half-life of approximately 2 h on ice. The results suggest that LTR termini bound by IN exhibit an allosteric effect to modulate full-site integration in vitro. Similar regulatory controls also appear to exist in vivo between the wt U3 and wt U5 LTR termini in retroviruses as well as purified retrovirus preintegration complexes that promoted full-site integration in vitro.

Cutaneous rat wounds express c49a, a novel gene with homology to the human melanoma differentiation associated gene, mda-7

We have used DD-PCR (differential display-polymerase chain reaction) to identify new genes that are over- or underexpressed during wound repair. DD-PCR performed on excisional wounds identified the expression of rat c49a. Cloning and sequence analysis of the rat c49a gene revealed high homology to a novel human melanoma differentiation associated gene, mda-7. The human mda-7gene isolated from melanoma cell lines, has been linked with human melanoma differentiation, and growth suppression. Moreover, transfection of human mda-7 constructs into human tumor cells suppresses the growth and colony formation of tumor cells from diverse origins. To confirm and relatively quantitate expression of rat c49a gene during repair, specific primer, reduced cycle RT-PCR (reverse transcription-PCR) was performed. RT-PCR showed an approximately 9 to 12-fold elevation of rat c49a mRNA at 12 h to 5 days above nonwounded controls that gradually decreased to approximately 1.5 to 3-fold by day 14. Cloning and sequence analysis of the entire 1200 base pair c49a gene product showed 78% nucleotide homology to human mda-7. Immunohistochemistry studies localized rat C49A expression primarily to fibroblast-like cells at the wound edge and base. The marked up-regulation of rat c49a transcripts during the inflammatory and early granulation tissue phases of wound repair where cellular processes such as re-epithelialization, angiogenesis, and fibroplasia predominate--suggest that c49a is associated with proliferation of fibroblasts in wound healing.

Recruitment of the retinoblastoma protein to c-Jun enhances transcription activity mediated through the AP-1 binding site

The retinoblastoma susceptibility gene product (RB) is a transcriptional modulator. One of the targets for this modulator effect is the AP-1 binding site within the c-jun and collagenase promoters. The physical interactions between RB and c-Jun were demonstrated by co-immunoprecipitation of these two proteins using anti-c-Jun or anti-RB antisera, glutathione S-transferase affinity matrix binding assays in vitro, and electrophoretic mobility shift assays. The C-terminal site of the leucine zipper of c-Jun mediated the interaction with RB. Although the B-pocket domain of RB alone bound to c-Jun, a second c-Jun binding site in the RB was also suggested. Mammalian two-hybrid-based assay provided corroborative evidence that transactivation of gene expression by RB required the C-terminal region of c-Jun. We conclude that RB enhances transcription activity mediated through the AP-1 binding site. Adenovirus E1A or human papillomavirus E7 inhibits RB-mediated transcription activity. These data reveal that the interactions between these two distinct classes of oncoproteins RB and c-Jun may be involved in controlling cell growth and differentiation mediated by transcriptional regulation.

Distinct roles of the co-activators p300 and CBP in retinoic-acid-induced F9-cell differentiation

The related proteins p300 and CBP (cAMP-response-element-binding protein (CREB)-binding protein)) are transcriptional co-activators that act with other factors to regulate gene expression and play roles in many cell-differentiation and signal transduction pathways. Both proteins have intrinsic histone-acetyltransferase activity and may act directly on chromatin, of which histone is a component, to facilitate transcription. They are also involved in growth control pathways, as shown by their interaction with the tumour suppressor p53 and the viral oncogenes E1A and SV40 T antigen. Here we report functional differences of p300 and CBP in vivo. We examined their roles during retinoic-acid-induced differentiation, cell-cycle exit and programmed cell death (apoptosis) of embryonal carcinoma F9 cells, using hammerhead ribozymes capable of cleaving either p300 or CBP messenger RNAs. F9 cells expressing a p300-specific ribozyme became resistant to retinoic-acid-induced differentiation, whereas cells expressing a CBP-specific ribozyme were unaffected. Similarly, retinoic-acid-induced transcriptional upregulation of the cell-cycle inhibitor p21Cip1 required normal levels of p300, but not CBP, whereas the reverse was true for p27Kip1. In contrast, both ribozymes blocked retinoic-acid-induced apoptosis, indicating that both co-activators are required for this process. Thus, despite their similarities, p300 and CBP have distinct functions during retinoic-acid-induced differentiation of F9 cells.

p300 and ATF-2 are components of the DRF complex, which regulates retinoic acid- and E1A-mediated transcription of the c-jun gene in F9 cells

Transcriptional activation of the c-jun gene is a critical event in the differentiation of F9 cells. In our previous studies we characterized an element [differentiation response element (DRE)] in the c-jun promoter that is both necessary and sufficient to confer the capacity for differentiation-dependent up-regulation. This element binds the differentiation regulatory factor (DRF) complex, of which one component is the adenovirus E1A-associated protein p300. We have now identified activation transcription factor-2 (ATF-2) as a DNA-binding subunit of the DRF complex. p300 and ATF-2 interact with each other in vivo and in vitro. The bromodomain and the C/H2 domain of p300 mediate the binding to ATF-2, which in turn requires a proline-rich region between amino acids 112 and 350 for its interaction with p300. The phosphorylation of the serine residue at position 121 of ATF-2 appears to be induced by protein kinase C alpha (PKC alpha) after treatment of cells with retinoic acid (RA) or induction with E1A. In cotransfection assays, wild-type ATF-2 enhanced the transcription of an E2/tk-luciferase construct, in conjunction with p300-E2. However, a mutant form of ATF-2 with a mutation at position 121 (pCMVATF-2(Ser121-Ala)) did not. These results suggest that ATF-2 and p300 cooperate in the control of transcription by forming a protein complex that is responsive to differentiation-inducing signals, such as RA or E1A, and moreover, that the phosphorylation of ATF-2 by PKC alpha is probably a signaling event in the pathway that leads to the transactivation of the c-jun gene in F9 cells.

A retinoblastoma susceptibility gene product, RB, targeting protease is regulated through the cell cycle

Degradation of cyclin B and cyclin-dependent kinase inhibitor, p27, at a specific time has been shown to play a critical role in regulating the cell cycle. SPase, a nuclear and cytosol protease with cathepsin B- and L-like proteolytic activity, has been identified in several cell lines. This proteolytic enzyme selectively degraded nuclear proteins such as retinoblastoma susceptibility gene product, RB, and transcription factor, SP-1. High levels of SPase activity were detected at the G1/S, moderate levels at the G1 and S phases, and undetectable activity at the M phase of synchronized CV-1 cells, suggesting that SPase activity is regulated through the cell cycle. Degradation of RB correlated with SPase activity throughout the cell cycle, suggesting that SPase regulates RB, which has a functional role in regulating cell cycle. These results demonstrated that SPase plays an integral role in regulating the nuclear regulator, RB, in controlling cell cycle progression.

Avian retrovirus U3 and U5 DNA inverted repeats. Role Of nonsymmetrical nucleotides in promoting full-site integration by purified virion and bacterial recombinant integrases

The U3 and U5 termini of linear retrovirus DNA contain imperfect inverted repeats that are necessary for the concerted insertion of the termini into the host chromosome by viral integrase. Avian myeloblastosis virus integrase can efficiently insert the termini of retrovirus-like DNA donor substrates (480 base pairs) by a concerted mechanism (full-site reaction) into circular target DNA in vitro. The specific activities of virion-derived avian myeloblastosis virus integrase and bacterial recombinant Rous sarcoma virus (Prague A strain) integrase (approximately 50 nM or less) appear similar upon catalyzing the full-site reaction with 3'-OH recessed wild type or mutant donor substrates. We examined the role of the three nonsymmetrical nucleotides located at the 5th, 8th, and 12th positions in the U3 and U5 15-base pair inverted repeats for their ability to modify the full-site and simultaneously, the half-site strand transfer reactions. Our data suggest that the nucleotide at the 5th position appears to be responsible for the 3-5-fold preference for wild type U3 ends over wild type U5 ends by integrase for concerted integration. Additional mutations at the 5th or 6th position, or both, of U3 or U5 termini significantly increased (approximately 3 fold) the full-site reactions of mutant donors over wild type donors.

Host site selection for concerted integration by human immunodeficiency virus type-1 virions in vitro

Host site selection for full-site integration by human immunodeficiency virus type-1 (HIV-1) intergrase (IN) from nonionic detergent-lysed virions was investigated. Linear retrovirus-like DNA (469 bp) possessing 3' OH recessed long terminal repeat termini was efficiently inserted by a bimolecular donor reaction into a supercoiled DNA target (2867 bp), producing the HIV-1 5-bp host site duplication. Sequence data were analyzed from 193 donor-target recombinants obtained from the linear 3.8-kb DNA product. The selection of host target sites appeared randomly distributed and was independent of lysis and assay conditions. The fidelity of the 5-bp duplications in comparison to other size duplications was highest (94%) with high-salt (300 mM NaCl) lysis of the virions and 60 mM NaCl for strand transfer using Mg2+ as the divalent cation. Base sequence analysis demonstrated some biases in the 5-bp duplications at the sites of strand transfer and at the immediate host sequences surrounding the duplications. In addition to the observed duplications, approximately 30% of the recombinants isolated from the linear 3.8-kb DNA product contained specific and repetitive small-size deletions. No deletions smaller that 17 bp were observed and the distance between the deletion sets had a periodicity of approximately 10 bp. The mechanisms involved in how HIV-1 IN produces the 5-bp duplications and the repetitive host site deletions are discussed.

A unique cathepsin-like protease isolated from CV-1 cells is involved in rapid degradation of retinoblastoma susceptibility gene product, RB, and transcription factor SP1

The regulation of transcription factors by kinase or phosphatase has been well-described. However, little is known about the inactivation of transcription factors or the nuclear regulators by proteolytic degradation. In this report, we purified a specific protease, SPase, from nuclear extracts of the green monkey kidney cell line, CV-1. Studies of biochemical characteristics and substrate specificity indicated that SPase is a cathepsin B-like cysteinyl protease. However, the two tryptic peptide sequences derived from the purified SPase are either identical or highly homologous to those of human cathepsin L, and furthermore, SPase shares immunoreactivity with both anti-human cathepsin L and anti-mouse cathepsin L antibody. The SPase was shown to be localized in both cytoplasm and nucleus when subcellular compartments of CV-1 cells were fractionated. Transcription factor, SP1, and retinoblastoma susceptible gene product, RB, are substrates of SPase while other nuclear factors such as c-Jun and c-Fos are not. These results implied that SPase plays an integral role in regulating a set of proteins in the nuclei. In vivo treatment of CV-1 cells with cysteinyl protease inhibitor, E-64d, protected RB from degradation. SPase failed to degrade underphosphorylated RB present in TPA induced terminally differentiated HL-60 or U937 cells. Phosphorylation of RB may cause conformational changes, thus facilitating proteolytic digestion. These observations suggest that an alternative pathway inactivates the function of RB in controlling cell growth. Therefore, a possible role of SPase may be to affect the stability of important regulators involved in controlling cellular proliferation and differentiation.

A subconjunctival degradable implant for cyclosporine delivery in corneal transplant therapy

The effect of local cyclosporine therapy upon corneal transplant survival was investigated. A high risk rabbit model with vascularized corneas was used to assess the efficacy of subconjunctivally implanted degradable devices for cyclosporine therapy. Animals were divided into four groups, receiving either no therapy, a placebo PLGA device, or drug containing devices implanted either at the time of transplantation or two weeks previous. The mean survival times of animals in the control and placebo groups were statistically equivalent (21 +/- 4 days vs 18 +/- 4 days). Devices containing CsA improved the survival time of grafts. Predosing the animals with CsA improved the survival time to 28 +/- 7 days, and CsA devices implanted at the time of transplantation increased the survival time to 35 +/- 7 days. The improvement in survival times was consistent with the in vitro drug release profiles. No systemic CsA was detected, suggesting that the effect may have been local. Histological assessment indicated that devices were well tolerated.

Phosphorylation of the adenovirus E1A-associated 300 kDa protein in response to retinoic acid and E1A during the differentiation of F9 cells

Transcription of the c-jun gene is up-regulated by either retinoic acid (RA) or adenovirus E1A during the differentiation of F9 cells. We show here that RA and E1A induce phosphorylation of the E1A-associated 300 kDa protein (p300) during the differentiation of F9 cells. The region of E1A that is required for interaction with cellular protein p300 overlaps with the region of E1A required for E1A to induce expression of the c-jun gene. Treatment of F9 cells with RA or infection of the cells by adenovirus led to a decrease in the electrophoretic mobility of p300. Phosphatase treatment of p300 from RA-treated or adenovirus-infected F9 cells reversed the changes in migration of p300, indicating that RA- and E1A-mediated changes in the mobility of p300 were due to phosphorylation. We also found factors, designated DRF1 and DRF2, that bound specifically to a sequence element that is necessary and sufficient for RA- and E1A-mediated up-regulation of the c-jun gene. The mobility of DRF complexes was changed by E1A or RA and the complexes were supershifted by addition of a polyclonal p300 antiserum. Moreover, overexpression of p300 resulted in an increase in the level of DRF1 complex. p300 fused to the DNA binding domain of the E2 protein of papilloma virus stimulated E2-dependent reporter activity in response to RA or E1A in F9 cells. Our results suggest that p300 is part of the DRF complexes, that it is differentially phosphorylated in undifferentiated versus differentiated cells and that it is likely involved in regulating transcription of the c-jun gene during F9 cell differentiation.

Induction by adenovirus-5 E1A of the differentiation phenotype of F9 teratocarcinoma cells involves a conserved region (CR1) of E1A

The effects of the E1A protein of adenovirus-5 on the differentiation program of F9 teratocarcinoma cells were examined by the stable introduction of plasmids that expressed wild-type or mutated forms of E1A. Constitutive expression of plasmids for most of the mutant E1As induced loss of expression of the cell-surface antigen SSEA-1 and the enhanced expression of genes specific for the differentiated phenotype of F9 cells, such as genes for laminin B1, tissue-type plasminogen activator (tPA) and type IV collagen, as well as the altered cell morphology that is associated with the differentiated state. However, such changes were not observed in the case of genes for mutant proteins from which a conserved region (CR1) of E1A had been deleted. Furthermore, no significant induction of expression of the c-jun gene or transactivation of the c-jun-CAT reporter gene were observed when the sequence that encodes CR1 of E1A had been deleted. A palindromic sequence element (DRE) of the c-jun promoter was essential for the E1A-mediated up-regulation of the c-jun gene. These results imply that CR1 is required for activation of the c-jun gene and that it is implicated in the growth arrest, expression of parietal endoderm-specific functions and the orderly differentiation of F9 cells.

A novel pathway for retinoic acid-induced differentiation of F9 cells that is distinct from receptor-mediated trans-activation

Retinoic acid (RA) has striking effects on vertebrate development and induces differentiation of several lines of cells including embryonal carcinoma F9 cells. It is generally accepted that the actions of RA are mediated by nuclear receptors for RA. However, we now provide evidence that F9 cells can differentiate in response to RA without trans-activation by nuclear receptors. Irreversible differentiation of F9 cells was induced by 18 h of exposure to RA with subsequent incubation in the absence of RA. This induction of differentiation was not blocked after inhibition of protein synthesis and mRNA synthesis during the 18-h treatment with RA, but the endogenous RA receptors failed to activate transcription from their target genes that contain the receptor-binding sequences. During the commitment to RA-induced differentiation, at least five sets of four phosphorylated proteins underwent changes in the absence of protein synthesis de novo. These results suggest that there is a novel pathway for the action of RA that is independent of nuclear receptor-mediated trans-activation.

Activation and serine phosphorylation of the p56lck protein tyrosine kinase in response to antigen receptor cross-linking in B lymphocytes

We show that cross-linking the B cell AgR with anti-Ig Abs activates p56lck (Lck) in both the immature B cell line WEHI-231 and mature resting B cells from mouse spleen. Anti-Ig-stimulated Lck activity peaked after 1 to 2 min, but remained elevated for at least 15 min. Consistent with the proposed role for src family tyrosine kinases in AgR signaling, we found that Lck could phosphorylate the cytoplasmic tails of the Ig-alpha and Ig-beta components of the B cell AgR in vitro. Lck phosphorylated both of the tyrosines in the Ig-beta AgR homology motif and one of the two tyrosines in the Ig-alpha AgR homology motif. Finally, we show that AgR ligation in B cells caused a significant portion of the Lck to migrate with an apparent molecular mass of 60 kDa on SDS-PAGE gels. Conversion of p56lck to p60lck was maximal at 5 to 15 min, at which times Lck activity in the cells was decreasing. This Lck "band shift" has been observed previously in activated T cells and correlates with phosphorylation of Lck at serine 59. We show that the 60-kDa form of Lck induced by AgR cross-linking in B cells is also phosphorylated at serine 59. Phosphorylation of Lck at this site in vitro decreases its activity. Thus, in B cells, AgR cross-linking activates Lck and subsequently activates a kinase that phosphorylates Lck at serine 59, a potential negative regulatory site.

Activation and serine phosphorylation of the p56lck protein tyrosine kinase in response to antigen receptor cross-linking in B lymphocytes

We show that cross-linking the B cell AgR with anti-Ig Abs activates p56lck (Lck) in both the immature B cell line WEHI-231 and mature resting B cells from mouse spleen. Anti-Ig-stimulated Lck activity peaked after 1 to 2 min, but remained elevated for at least 15 min. Consistent with the proposed role for src family tyrosine kinases in AgR signaling, we found that Lck could phosphorylate the cytoplasmic tails of the Ig-alpha and Ig-beta components of the B cell AgR in vitro. Lck phosphorylated both of the tyrosines in the Ig-beta AgR homology motif and one of the two tyrosines in the Ig-alpha AgR homology motif. Finally, we show that AgR ligation in B cells caused a significant portion of the Lck to migrate with an apparent molecular mass of 60 kDa on SDS-PAGE gels. Conversion of p56lck to p60lck was maximal at 5 to 15 min, at which times Lck activity in the cells was decreasing. This Lck "band shift" has been observed previously in activated T cells and correlates with phosphorylation of Lck at serine 59. We show that the 60-kDa form of Lck induced by AgR cross-linking in B cells is also phosphorylated at serine 59. Phosphorylation of Lck at this site in vitro decreases its activity. Thus, in B cells, AgR cross-linking activates Lck and subsequently activates a kinase that phosphorylates Lck at serine 59, a potential negative regulatory site.

Transforming growth factor beta 1-mediated induction of junB is selectively inhibited by expression of Ad.12-E1A

Transforming growth factor beta (TGF-beta), a multifunctional polypeptide growth factor, regulates the expression of many genes critical to cell cycle progression, such as members of the jun gene family which encode components of the transcription factor complex AP-1. The transforming proteins encoded by the early region 1A of adenovirus12 (Ad.12-E1A) abrogate some of the cellular responses to TGF-beta as well as affecting, differentially, the expression of cellular jun genes. Our data demonstrate that expression of Ad.12-E1A in rat 3Y1 fibroblast cells inhibits induction of junB by TGF-beta 1 while not altering the regulation of junB by phorbol ester or serum. Regulation of c-jun gene expression by TGF-beta 1, phorbol ester, and serum is not appreciably altered by the expression of Ad.12-E1A. Inhibition of TGF-beta induced junB expression is not due to a defect in TGF-beta/receptor interaction on Ad.12-E1A transformed cells and is not observed in other isotypic fibroblast cells transformed by SV40 or polyomavirus. These data suggest that multiple, independent, intracellular signal transduction pathways exist which mediate genomic responses to TGF-beta. Cellular expression of Ad.12-E1A-12S gene products results in selective disruption of some TGF-beta 1 signaling cascades and not those activated by phorbol ester or serum. These data further suggest that some cellular targets which mediate TGF-beta 1 action may also be unique targets of action for the E1A-12S transforming protein of adenovirus12.

Insulin-like growth factor-I stimulates c-fos and c-jun transcription in PC12 cells

We analyzed the effects of insulin-like growth factor-I (IGF-I), a polypeptide growth factor which exerts mitogenic effects via specific membrane receptors. The control of IGF-I on c-fos and c-jun transcription was studied in PC12 cells. Gel mobility shift assays with a labeled AP1 consensus binding sequence (TRE: TGACTCA) showed an increase in specific binding upon trIGF-treatment. Gene transfer studies revealed that the increase in AP1 binding is functional since IGF-I stimulates transcription from a reporter gene containing the minimal TRE linked to the chloramphenicol acetyl transferase (CAT) reporter gene. To further characterize the molecular mechanism by which IGF-I increases AP1 activity, we analysed the transcription regulation of c-fos and c-jun using reporter genes containing the respective promoters or specific regulatory elements. Deletion studies with the c-jun promoter, showed that IGF-I stimulates c-jun transcription via a cis acting element(s) localized within the 132 base pairs prior to the transcription start site; possibly the AP1 like element TGACATCA. Similar studies revealed that c-fos stimulation by IGF-I requires the presence of a regulatory sequence spanning the dyad symmetry element (DSE) and the fos AP1-like sequence (FAP). Further experiments using specific elements linked to the minimal unresponsive c-fos promoter, showed that the DSE is the main target for c-fos induction by IGF-I.