elastin and Prostatic-Neoplasms

Prostate cancer cells frequently overexpress the gastrin-releasing peptide receptor, and various strategies have been applied in preclinical settings to target this receptor for the specific delivery of anticancer compounds. Recently, elastin-like polypeptide (ELP)-based self-assembling micelles with tethered GRP on the surface have been suggested to actively target prostate cancer cells. Poorly soluble chemotherapeutics such as docetaxel (DTX) can be loaded into the hydrophobic cores of ELP micelles, but only limited drug retention times have been achieved. Herein, we report the generation of hybrid ELP/liposome nanoparticles which self-assembled rapidly in response to temperature change, encapsulated DTX at high concentrations with slow release, displayed the GRP ligand on the surface, and specifically bound to GRP receptor expressing PC-3 cells as demonstrated by flow cytometry. This novel type of drug nanocarrier was successfully used to reduce cell viability of prostate cancer cells in vitro through the specific delivery of DTX.

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Survival; Docetaxel; Drug Delivery Systems; Elastin; Humans; Hydrophobic and Hydrophilic Interactions; Liposomes; Male; Micelles; Molecular Targeted Therapy; Nanoparticles; Peptides; Prostatic Neoplasms; Receptors, Bombesin; Taxoids

Intratumoral radiation therapy - 'brachytherapy' - is a highly effective treatment for solid tumors, particularly prostate cancer. Current titanium seed implants, however, are permanent and are limited in clinical application to indolent malignancies of low- to intermediate-risk. Attempts to develop polymeric alternatives, however, have been plagued by poor retention and off-target toxicity due to degradation. Herein, we report on a new approach whereby thermally sensitive micelles composed of an elastin-like polypeptide (ELP) are labeled with the radionuclide (131)I to form an in situ hydrogel that is stabilized by two independent mechanisms: first, body heat triggers the radioactive ELP micelles to rapidly phase transition into an insoluble, viscous coacervate in under 2 min; second, the high energy β-emissions of (131)I further stabilize the depot by introducing crosslinks within the ELP depot over 24h. These injectable brachytherapy hydrogels were used to treat two aggressive orthotopic tumor models in athymic nude mice: a human PC-3 M-luc-C6 prostate tumor and a human BxPc3-luc2 pancreatic tumor model. The ELP depots retained greater than 52% and 70% of their radioactivity through 60 days in the prostate and pancreatic tumors with no appreciable radioactive accumulation (≤ 0.1% ID) in off-target tissues after 72h. The (131)I-ELP depots achieved >95% tumor regression in the prostate tumors (n=8); with a median survival of more than 60 days compared to 12 days for control mice. For the pancreatic tumors, ELP brachytherapy (n=6) induced significant growth inhibition (p=0.001, ANOVA) and enhanced median survival to 27 days over controls.

Topics: Animals; Brachytherapy; Cell Line, Tumor; Delayed-Action Preparations; Elastin; Hot Temperature; Humans; Hydrogels; Injections; Iodine Radioisotopes; Male; Mice, Inbred BALB C; Mice, Nude; Micelles; Pancreas; Pancreatic Neoplasms; Peptides; Phase Transition; Prostate; Prostatic Neoplasms

In recent years G protein-coupled receptors (GPCRs) have emerged as crucial tumorigenic factors that drive aberrant cancer growth, metastasis and angiogenesis. Consequently, a number of GPCRs are strongly expressed in cancer derived cell lines and tissue samples. Therefore a rational anti-cancer strategy is the design of nano-medicines that specifically target GPCRs to bind and internalise cytotoxic drugs into cancer cells. Herein, we report the genetic engineering of a self-assembling nanoparticle based on elastin-like polypeptide (ELP), which has been fused with gastrin releasing peptide (GRP). These nanoparticles increased intracellular calcium concentrations when added to GRP receptor positive PC-3 prostate cancer cells, demonstrating specific receptor activation. Moreover, GRP-displaying fluorescent labelled nanoparticles showed specific cell-surface interaction with PC-3 prostate cancer cells and increased endocytic uptake. These nanoparticles therefore provide a targeted molecular carrier system for evaluating the delivery of cytotoxic drugs into cancer cells.

Topics: Anilino Naphthalenesulfonates; Cell Line, Tumor; Drug Carriers; Elastin; Endocytosis; Fluorescent Dyes; Gastrin-Releasing Peptide; Genetic Engineering; Humans; Male; Micelles; Peptides; Prostatic Neoplasms; Receptors, Bombesin; Recombinant Fusion Proteins

Brachytherapy is a common clinical technique involving implantation of sealed radioactive "seeds" within a tumor to selectively irradiate the tumor mass while minimizing systemic toxicity. To mitigate the disadvantages associated with complex surgical implantation and subsequent device removal procedures, we have developed an alternative approach using a genetically encoded peptide polymer solution composed of a thermally responsive elastin-like polypeptide (ELP) radiolabeled with (131)I that self-assembles into radionuclide seeds upon intratumoral injection. The formation of these nontoxic and biodegradable polymer seeds led to prolonged intratumoral retention (~85% ID/tumor 7 days postinjection) of the radionuclide, elicited a tumor growth delay in 100% of the tumors in two human xenografts (FaDu and PC-3), and cured more than 67% of tumor-bearing animals after a single administration of labeled ELP. These results suggest that in situ self-assembly of biodegradable and injectable radionuclide-containing polypeptide seeds could be a promising therapeutic alternative to conventional brachytherapy.

Topics: Animals; Brachytherapy; Carcinoma, Squamous Cell; Cell Line, Tumor; Drug Delivery Systems; Elastin; Female; Humans; Hypopharyngeal Neoplasms; Iodine Radioisotopes; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Peptides; Prostatic Neoplasms; Tandem Repeat Sequences; Xenograft Model Antitumor Assays

Resistance of cancer cells to hyperthermic temperatures and spatial limitations of nanoparticle-induced hyperthermia necessitates the identification of effective combination treatments that can enhance the efficacy of this treatment. Here we show that novel polypeptide-based degradable plasmonic matrices can be employed for simultaneous administration of hyperthermia and chemotherapeutic drugs as an effective combination treatment that can overcome cancer cell resistance to hyperthermia.. Novel gold nanorod elastin-like polypeptide matrices were generated and characterized. The matrices were also loaded with the heat-shock protein (HSP)90 inhibitor 17-(allylamino)-17-demethoxygeldanamycin (17-AAG), currently in clinical trials for different malignancies, in order to deliver a combination of hyperthermia and chemotherapy.. Laser irradiation of cells cultured over the plasmonic matrices (without 17-AAG) resulted in the death of cells directly in the path of the laser, while cells outside the laser path did not show any loss of viability. Such spatial limitations, in concert with expression of prosurvival HSPs, reduce the efficacy of hyperthermia treatment. 17-AAG-gold nanorod-polypeptide matrices demonstrated minimal leaching of the drug to surrounding media. The combination of hyperthermic temperatures and the release of 17-AAG from the matrix, both induced by laser irradiation, resulted in significant (>90%) death of cancer cells, while 'single treatments' (i.e., hyperthermia alone and 17-AAG alone) demonstrated minimal loss of cancer cell viability (<10%).. Simultaneous administration of hyperthermia and HSP inhibitor release from plasmonic matrices is a powerful approach for the ablation of malignant cells and can be extended to different combinations of nanoparticles and chemotherapeutic drugs for a variety of malignancies.

Topics: Benzoquinones; Cell Line, Tumor; Cell Survival; Cysteine; Doxorubicin; Elastin; Gold; HSP90 Heat-Shock Proteins; Humans; Hyperthermia, Induced; Lactams, Macrocyclic; Low-Level Light Therapy; Male; Nanoparticles; Nanotubes; Peptides; Prostatic Neoplasms

Clinically aggressive neoplastic development appears to be associated with extensive extracellular matrix biosynthesis. Collagen, non-collagenous protein and elastin from 21 specimens of benign hypertrophic prostate (BPH) and 15 samples of cancerous prostate were determined. Collagen and non-collagenous protein concentrations of BPH were similar to those in prostatic carcinoma. The elastin concentration of well or moderately differentiated prostatic carcinoma was greater than that in BPH specimens. These results may provide an explanation as to the early antecedent or possible aetiology of prostatic carcinoma.

Topics: Adenocarcinoma; Aged; Collagen; Connective Tissue; Elastin; Humans; Male; Prostate; Prostatic Hyperplasia; Prostatic Neoplasms

The extracellular matrix (ECM) has been shown to play a major role in cell structure and function. Several studies have demonstrated that the ECM can alter cell morphology and effect DNA synthesis and gene expression. The ECM also interacts with growth hormones which have been shown to be located in or near the ECM where they are believed to effect cell structure and function. In the nontransformed cell, these ECM and hormone-mediated effects appear to be tightly regulated and this is believed to be accomplished through cell receptor-tissue matrix interactions. We, therefore, undertook a study to determine the effects of a variety of ECM components and the adrogenic hormone dihydrotestosterone (DHT) on the structure and function of the human prostate cancer cell line, LNCaP. The effects of individual matrix components in the presence and absence of 1 nM DHT on the static and dynamic morphology, growth rate, and PSA production of the LNCaP cell line were studied. We determine that the ECM and DHT interact in complex ways to effect cell structure and function. DHT produced alterations in cytoplasmic structure that increased cell size and decreased the nuclear area/cytoplasmic area ratio. Dynamic cell structure as measured by cell motility was very sensitive to the ECM components and the presence of DHT. PSA and growth could be regulated by substratum and DHT and there was an inverse relationship between PSA production and growth rate. These data exemplify the complex interactions which occur between prostate cancer cells, ECM components, and exogenous DHT that are reflected in cell structure and function.

Topics: Antigens, Neoplasm; Biomarkers, Tumor; Cell Movement; Cell Nucleus; Cell Survival; Collagen; Dihydrotestosterone; Elastin; Humans; Laminin; Male; Prostate-Specific Antigen; Prostatic Neoplasms; Tumor Cells, Cultured

Cancer cell motility has been associated with metastatic potential of sublines of the Dunning R-3227 rat prostatic adenocarcinoma model. However, three sublines of high motility lacked the capacity for metastasis. In all previous works, motility has been studied upon plastic and only upon attached cells at least 18 h after gravity plating. We studied two highly motile sublines; MAT-LyLu metastasizes to lungs and lymph nodes whereas PIF-1 metastasizes rarely. We compared the motility and attachment capability of cells from the Dunning model in serum-free media upon plastic, glass, laminin, type IV collagen, fibronectin, and elastin to determine whether study upon more physiological surfaces could better explain the discrepancy in metastatic capability observed in vivo. In the high-motility low-metastatic PIF-1 and high-motility high-metastatic MAT-Lylu sublines, membrane ruffling, pseudopodal extension, and cellular translation upon plastic in serum-free media were reduced (P less than 0.0001) by 33 and 31, 70 and 60, and 77 and 65%, respectively. When returned to serum-containing media, biological characteristics (histology, chromosomal number, growth rate, host survival, and metastatic potential) were unchanged. Motility was affected by substrate (analysis of variance, P less than 0.05); however, no consistent pattern of enhancement or detriment occurred in any substrate across both sublines. When motility was compared between sublines, membrane ruffling and cellular translation were relatively unaffected by substrate, whereas pseudopodal extension was altered significantly by different substrates. However, upon individual substrates, no significant differences in motility existed between the two sublines to resolve the inconsistency of high-motility but low-metastatic potential in the PIF-1 subline. Therefore, we examined cell attachment, since in order for a metastatic cell to be motile upon substrate, it must first attach to it. Percentage of 10(5) cells attached was determined in serum-free media with the use of a cell counter after 1, 2, 4, 8, and 16 h on plastic and plastic coated with laminin, fibronectin, elastin, or type IV collagen. Cell attachment increased with time (P less than 0.05) on all substrates for MAT-LyLu (r = 0.95) and PIF-1 (r = 0.98). Attachment of MAT-LyLu cells was impaired by fibronectin and enhanced by elastin, laminin, and type IV collagen compared to plastic at all time points.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Adenocarcinoma; Animals; Cell Adhesion; Cell Movement; Collagen; Culture Media, Serum-Free; Elastin; Fibronectins; Laminin; Male; Neoplasm Metastasis; Prostatic Neoplasms; Rats; Tumor Cells, Cultured