Unveiling the Molecular Mechanism of Trastuzumab Resistance in SKBR3 and BT474 Cell Lines for HER2 Positive Breast Cancer

HER2-positive breast cancer is one of the most prevalent forms of cancer among women worldwide. Generally, the molecular characteristics of this breast cancer include activation of human epidermal growth factor receptor-2 (HER2) and hormone receptor activation. HER2-positive is associated with a higher death rate, which led to the development of a monoclonal antibody called trastuzumab, specifically targeting HER2. The success rate of HER2-positive breast cancer treatment has been increased; however, drug resistance remains a challenge. This fact motivated us to explore the underlying molecular mechanisms of trastuzumab resistance. For this purpose, a two-fold approach was taken by considering well-known breast cancer cell lines SKBR3 and BT474. In the first fold, trastuzumab treatment doses were optimized separately for both cell lines. This was done based on the proliferation rate of cells in response to a wide variety of medication dosages. Thereafter, each cell line was cultivated with a steady dosage of herceptin for several months. During this period, six time points were selected for further in vitro analysis, ranging from the untreated cell line at the beginning to a fully resistant cell line at the end of the experiment. In the second fold, nucleic acids were extracted for further high throughput-based microarray experiments of gene and microRNA expression. Such expression data were further analyzed in order to infer the molecular mechanisms involved in the underlying development of trastuzumab resistance. In the list of differentially expressed genes and miRNAs, multiple genes (e.g., BIRC5, E2F1, TFRC, and USP1) and miRNAs (e.g., hsa miR 574 3p, hsa miR 4530, and hsa miR 197 3p) responsible for trastuzumab resistance were found. Downstream analysis showed that TFRC, E2F1, and USP1 were also targeted by hsa-miR-8485. Moreover, it indicated that miR-4701-5p was highly expressed as compared to TFRC in the SKBR3 cell line. These results unveil key genes and miRNAs as molecular regulators for trastuzumab resistance.

Novel insight into Robert's cytoprotection: complex therapeutic effect of cytoprotective pentadecapeptide pentadecapeptide BPC 157 in rats with perforated stomach throughout modulation of nitric oxide-system. Comparison with L-arginine, ranitidine and pantoprazole therapy and L-NG-nitro-L-arginine methyl ester worsening

Surgically perforated stomach (since direct injury in rats until persisting defect and huge adhesions (day 1, day 7)) fairly represent an unresolved cytoprotection issue, and thereby, we focused resolving of the immediate triad, particular vascular failure (vessels 'disappear'/empty), prolonged bleeding, debilitated defect large widening. Agents (mg/kg) or saline (controls) were given at 1 min post-injury as an abdominal bath (10 ml/rat throughout 2 min). Within 1 - 15 min post-injury period, with cytoprotective BPC 157 (0.01 μg), the rapidly restored vessels 'run' (vessels filled/reappeared) toward the perforated defect, and there is less bleeding, and defect contraction; advanced perforated lesion healing (day 1) to complete healing (day 7), and less adhesions. With pantoprazole (10 mg), early (vessels (worsening), bleeding (prolongation), defect (attenuated widening)) effect means eventual lesions and adhesions severity as in controls. Ranitidine (10 mg) early effect (vessels (improvement), bleeding (less bleeding), defect (eliminated widening, defect not changed)) means final lesions attenuation, but not complete healing, less adhesions. L-NAME (5 mg) early (vessels worsening, less bleeding, attenuated defect widening) and final (lesions aggravation, more adhesions) effect, versus L-arginine (100 mg) early (vessels improvement, more bleeding, attenuated defect widening) and final (lesions attenuation, less adhesions) effect, combined few simultaneously occurring nitric oxide (NO)-system distinct processes. Finally, in the stomach tissue surrounding defect, increased malondialdehyde (MDA)- and decreased NO-values, BPC 157 reversed to the normal healthy values, and mRNA expression studies (Cox2, VEGFa, Nos1, Nos 2, Nos3, Nkap (NF-kappa-B-activating protein gene)), done at that very early post-perforation-time, indicate a way how BPC 157 may act beneficially in the perforated stomach lesion throughout NO- and prostaglandinds-system.

Nonsteroidal anti-inflammatory drugs-induced failure of lower esophageal and pyloric sphincter and counteraction of sphincters failure with stable gatric pentadecapeptide BPC 157 in rats

The sphincters failure is a part of NSAIDs-toxicity that can be accordingly counteracted. We used a safe stable gastric pentadecapeptide BPC 157 (GEPPPGKPADDAGLV, MW 1419), LD1 not achieved, since successful in inflammatory bowel disease trials, and counteracts esophagitis, sphincters failure, gastrointestinal ulcer and skin ulcer, external and internal fistulas in rats, and particularly counteracts all NSAIDs-lesions. We assessed lower esophageal sphincter and pyloric sphincter pressure (cmH₂O) in rats treated with various NSAIDs regimens, at corresponding time points, known to produce stomach, small intestine lesions, hepatotoxicity and encephalopathy. Assessment was after diclofenac (12.5 mg/kg, 40 mg/kg intraperitoneal challenge), ibuprofen (400 mg/day/kg intraperitoneally for 4 weeks), paracetamol (5.0 g/kg intraperitoneal challenge), aspirin (400 mg/kg intraperitoneally or intragastrically), celecoxib (0.5 mg/kg, 1.0 mg/kg intraperitoneally). BPC 157 (10 μg/kg, 10 ng/kg) was given immediately after NSAIDs (intraperitoneally or intragastrically) or given in drinking water. Regularly, in all control NSAIDs fall of pressure occurred in both sphincters rapidly and then persisted. By contrast, in all NSAIDs-rats that received BPC 157, initial fall of pressure was minimized and pressure values restored to normal values. All tested NSAIDs decrease pressure in both sphincters, whilst BPC 157 counteracts their effects and restored both sphincters function.

Duodenocutaneous fistula in rats as a model for "wound healing-therapy" in ulcer healing: the effect of pentadecapeptide BPC 157, L-nitro-arginine methyl ester and L-arginine

While very rarely reported, duodenocutanenous fistula research might alter the duodenal ulcer disease background and therapy. Our research focused on rat duodenocutaneous fistulas, therapy, stable gastric pentadecapeptide BPC 157, an anti-ulcer peptide that healed other fistulas, nitric oxide synthase-substrate L-arginine, and nitric oxide synthase-inhibitor L-nitro-arginine methyl ester (L-NAME). The hypothesis was, duodenal ulcer-healing, like the skin ulcer, using the successful BPC 157, with nitric oxide-system involvement, the "wound healing-therapy", to heal the duodenal ulcer, the fistula-model that recently highlighted gastric and skin ulcer healing. Pressure in the lower esophageal and pyloric sphincters was simultaneously assessed. Duodenocutaneous fistula-rats received BPC 157 (10 μg/kg or 10 ng/kg, intraperitoneally or perorally (in drinking water)), L-NAME (5 mg/kg intraperitoneally), L-arginine (100 mg/kg intraperitoneally) alone and/or together, throughout 21 days. Duodenocutaneous fistula-rats maintained persistent defects, continuous fistula leakage, sphincter failure, mortality rate at 40% until the 4(th) day, all fully counteracted in all BPC 157-rats. The BPC 157-rats experienced rapidly improved complete presentation (maximal volume instilled already at 7(th) day). L-NAME further aggravated the duodenocutaneous fistula-course (mortality at 70% until the 4(th) day); L-arginine was beneficial (no mortality; however, maximal volume instilled not before 21(st) day). L-NAME-worsening was counteracted to the control level with the L-arginine effect, and vice versa, while BPC 157 annulled the L-NAME effects (L-NAME + L-arginine; L-NAME + BPC 157; L-NAME + L-arginine + BPC 157 brought below the level of the control). It is likely that duodenocutaneous fistulas, duodenal/skin defect simultaneous healing, reinstated sphincter function, are a new nitric oxide-system related phenomenon. In conclusion, resolving the duodenocutanenous fistulashealing, nitric oxide-system involvement, should illustrate further wound healing therapy to heal duodenal ulcers.

Stable gastric pentadecapeptide BPC 157 heals cysteamine-colitis and colon-colon-anastomosis and counteracts cuprizone brain injuries and motor disability

Stable gastric pentadecapeptide BPC 157 was suggested to link inflammatory bowel disease and multiple sclerosis, and thereby, shown to equally counteract the models of both of those diseases. For colitis, cysteamine (400 mg/kg intrarectally (1 ml/rat)) and colon-colon anastomosis (sacrifice at day 3, 5, 7, and 14) were used. BPC 157 (10 μg/kg, 10 ng/kg) was applied either intraperitoneally once time daily (first application immediately after surgery, last at 24 hours before sacrifice) or per-orally in drinking water (0.16 μg/ml/12 ml/day till the sacrifice) while controls simultaneously received an equivolume of saline (5 ml/kg) intraperitoneally or drinking water only (12 ml/day). A multiple sclerosis suited toxic rat model, cuprizone (compared with standard, a several times higher regimen, 2.5% of diet regimen + 1 g/kg intragastrically/day) was combined with BPC 157 (in drinking water 0.16 μg or 0.16 ng/ml/12 ml/day/rat + 10 μg or 10 ng/kg intragastrically/day) till the sacrifice at day 4. In general, the controls could not heal cysteamine colitis and colon-colon anastomosis. BPC 157 induced an efficient healing of both at the same time. Likewise, cuprizone-controls clearly exhibited an exaggerated and accelerated damaging process; nerve damage appeared in various brain areas, with most prominent damage in corpus callosum, laterodorsal thalamus, nucleus reunions, anterior horn motor neurons. BPC 157-cuprizone rats had consistently less nerve damage in all damaged areas, especially in those areas that otherwise were most affected. Consistently, BPC 157 counteracted cerebellar ataxia and impaired forelimb function. Thereby, this experimental evidence advocates BPC 157 in both inflammatory bowel disease and multiple sclerosis therapy.