MEK1 Mutant-A375 Isogenic Cell Line

Anti-cancer drug screening, BRAF drug resistant melanoma model, tumor-associated MEK1Q56P/BRAFV600E research, MAPK/ERK signaling pathway. Ideally the parental cell line (ATCC^® CRL-1619™) is included as a control for drug-sensitive response in experiments with this cell line.

This is a malignant BRAFV600E/MEK1Q56P mutant isogenic line derived from the parental A375 (ATCC CRL-1619) cell line. The c.167A>C knock-in mutation encoding MEK1 p.Q56P protein expression was generated at ATCC by utilizing the CRISPR/Cas9 gene editing technology. This is a heterozygous mutation expressing the MEK1 wild-type and the c.167A>C mutant alleles.

BRAF is a proto-oncogene encoding B-RAF, a serine/threonine kinase of the RAF family that acts downstream of RAS and upstream of MEK in the MAPK/ERK signaling pathway. Mutations in BRAF lead to excessive cellular proliferation, differentiation, and survival. BRAF V600E mutations are present in 50% of melanomas and although there are current BRAF inhibitors used as successful therapeutics, patients often become resistant to drugs several months following treatment. One mechanism of resistance to these inhibitors is caused by upstream secondary RAS acquired mutations. The MEK1 Q56P mutant isogenic line, ATCC CRL-1619IG-3 has been validated at the genomic, transcript, and protein bio-functional levels and exhibits significant resistance to the BRAF inhibitors Dabrafineb and Vemurafenib, as well as the MEK inhibitor trametinib when compared to its parental cell line. Furthermore, A-375 MEK1Q56P (ATCC CRL-1619IG-3™) cells display increased sensitivity to combination MEK/BRAF inhibitor treatments, making this line an ideal model system for the development of novel combination therapies targeting multiple points in the RAS-RAF-MEK-ERK-MAPK signaling pathway, as well as for the screening of new potential BRAF and MEK inhibitors.

1. Check all containers for leakage or breakage.
2. Remove the frozen cells from the dry ice packaging and immediately place the cells at a temperature below ­-130°C, preferably in liquid nitrogen vapor, until ready for use.

To ensure the highest level of viability, thaw the vial and initiate the culture as soon as possible upon receipt. If upon arrival, continued storage of the frozen culture is necessary, it should be stored in liquid nitrogen vapor phase and not at -70°C.  Storage at -70°C will result in loss of viability.  

1. Thaw the vial by gentle agitation in a 37°C water bath. To reduce the possibility of contamination, keep the O-ring and cap out of the water.  Thawing should be rapid (approximately 2 minutes).
2. Remove the vial from the water bath as soon as the contents are thawed, and decontaminate by dipping in or spraying with 70% ethanol. All of the operations from this point on should be carried out under strict aseptic conditions.
3. Transfer the vial contents to a centrifuge tube containing  9.0 mL complete culture medium. and spin at approximately 150 x g for 5 to 7 minutes.
4. Resuspend cell pellet with the recommended complete medium (see the specific batch information for the culture recommended dilution ratio). It is important to avoid excessive alkalinity of the medium during recovery of the cells.  It is suggested that, prior to the addition of the vial contents, the culture vessel containing the complete growth medium be placed into the incubator for at least 15 minutes to allow the medium to reach its normal pH (7.0 to 7.6). pH (7.0 to 7.6).
5. Incubate the culture at 37°C in a suitable incubator.  A 5% CO₂ in air atmosphere is recommended if using the medium described on this product sheet.

1. Remove and discard culture medium.
2. Briefly rinse the cell layer with 0.25% (w/v) Trypsin- 0.53 mM EDTA solution to remove all traces of serum that contains trypsin inhibitor.
3. Add 2.0 to 3.0 mL of Trypsin-EDTA solution to flask and observe cells under an inverted microscope until cell layer is dispersed (usually within 5 to 15 minutes).
   Note: To avoid clumping do not agitate the cells by hitting or shaking the flask while waiting for the cells to detach. Cells that are difficult to detach may be placed at 37°C to facilitate dispersal.
4. Add 6.0 to 8.0 mL of complete growth medium and aspirate cells by gently pipetting.
5. Add appropriate aliquots of the cell suspension to new culture vessels.
   Cultures can be established between 1.0 x 10⁴ and 4 x 10⁴ viable cells/cm².
6. Incubate cultures at 37°C.

The product is provided 'AS IS' and the viability of ATCC^® products is warranted for 30 days from the date of shipment, provided that the customer has stored and handled the product according to the information included on the product information sheet, website, and Certificate of Analysis. For living cultures, ATCC lists the media formulation and reagents that have been found to be effective for the product. While other unspecified media and reagents may also produce satisfactory results, a change in the ATCC and/or depositor-recommended protocols may affect the recovery, growth, and/or function of the product. If an alternative medium formulation or reagent is used, the ATCC warranty for viability is no longer valid.  Except as expressly set forth herein, no other warranties of any kind are provided, express or implied, including, but not limited to, any implied warranties of merchantability, fitness for a particular purpose, manufacture according to cGMP standards, typicality, safety, accuracy, and/or noninfringement.

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