BioVector® Mel202 (M202) Human Uveal Melanoma Cell Line / Mel202 (M202) 人眼葡萄膜黑色素瘤细胞系

一 产品基本信息与遗传学背景

• 细胞名称：Mel202（常简写为 M202），人眼葡萄膜黑色素瘤细胞。

• 物种来源：人源（Homo sapiens），雌性（Female）。最初由荷兰莱顿大学医学中心（Leiden University Medical Center）Martine Jager 教授团队从人类原发性葡萄膜黑色素瘤（Primary Uveal Melanoma, UM）组织中分离并成功建立株系。该细胞作为欧洲委员会第五框架基础设施项目“ESTDAB”（欧洲可检索肿瘤细胞系数据库）的一部分（编号：ESTDAB-128），获得了极清晰的免疫学与遗传学背景表征。

• 遗传学与突变特征（关键背景）：

  • GNAQ 突变（经典特征）：Mel202 细胞携带 GNAQ 基因经典热点激活突变（p.Gln209Leu / c.626A>T）。超过 80% 的原发性葡萄膜黑色素瘤具备 GNAQ 或 GNA11 突变，这导致其下游的 MAPK 信号通路（RAS-RAF-MEK-ERK）及 YAP/TAZ 通路发生结构性持续激活。

  • SF3B1 突变：同时携带剪切因子基因 SF3B1 突变（p.Arg625Gly），该突变通常与葡萄膜黑色素瘤晚期发生转移的风险密切相关。

  • CDKN2A 突变：存在 CDKN2A 基因失活突变（p.Leu65Argfs*52），导致细胞周期检查点调控机制缺陷。

  • BAP1 状态：保留了 BAP1 的表达（BAP1-wildtype / BAP1-positive），这符合其源自非高度恶性早期/或特定转移表型原发灶的生物学特征。

• 免疫学标志物：HLA 分型明确（如 HLA-A*02:01 阳性）。表达黑色素瘤相关抗原 MART-1（Melan-A）。这使其成为黑色素瘤免疫治疗研究中少数兼具特定 HLA 限制性与特异性抗原表达的细胞模型。

• 生长特性：贴壁生长（Adherent），主要呈现上皮细胞样（Epithelial-like）、梭形或多角形交织生长形态，细胞形态较为紧凑。

• 生物安全级别：1-2 级（BSL-1/2）。虽然源自人类原发肿瘤，但在常规操作中仍需作为潜在的人源传染源，在二级生物安全柜内执行规范的标准细胞房操作。

二 核心科研价值与转化医学应用

Mel202 细胞在眼部肿瘤学以及靶向治疗耐药机制研究中具有不可替代的作用：

1. 葡萄膜黑色素瘤靶向药物筛选与耐药机制（Targeted Therapy & MAPK Inhibition）：

   由于皮肤黑色素瘤通常由 BRAF 突变（如 $BRAF^{V600E}$）驱动，而眼部葡萄膜黑色素瘤（UM）主要由 GNAQ/GNA11 驱动，因此对常规的 BRAF 抑制剂天然耐药。Mel202 作为典型的 GNAQ 突变细胞模型，被广泛用于开发和评价新型 MEK 抑制剂（如 Trametinib, Selumetinib, TAK733）、PKC 抑制剂以及 ARF6 抑制剂的单药或联合用药毒杀动力学。

2. 过继性免疫治疗与 T 细胞毒性评估（Immunotherapy & CTL Assay）：

   由于 Mel202 稳定表达 MART-1 抗原且 HLA-A*02:01 呈阳性，它是评价 MART-1 特异性细胞毒性 T 淋巴细胞（CTL）或 TCR-T 细胞体外靶向杀伤效能、细胞因子（如 IFN-$\gamma$、TNF-$\alpha$）释放反应的国际标准靶细胞模型，常用于研究放化疗敏化剂（如顺铂 CDDP）如何通过上调 FasR 增强 CTL 对其的非特异性清除。

3. 眼部肿瘤体内移植瘤模型构建（Xenograft Modeling）：

   可在免疫缺陷型小鼠（如 BALB/c Nude、NOD-SCID）皮下、或原位眼压前房/脉络膜接种构建眼部黑色素瘤移植瘤模型，用于观察肿瘤在眼部微环境中的原位浸润、以及研究其自发向肝脏等远端器官转移的靶向偏好性。

三 实验室细胞复苏、扩增传代与冷冻保存标准步骤

1. 完全培养基配置

Mel202 细胞在常规含营养素的基质中生长良好，但需要充足的谷氨酰胺支持：

• 基础培养基：RPMI 1640 培养基（推荐）（含 2.0 mM L-Glutamine 谷氨酰胺）。

• 完全添加剂成分：

  • 10% 优质灭活胎牛血清（FBS）。

  • 1% 灭菌双抗（Penicillin-Streptomycin, 100 U/mL）。

• 培养条件：37 摄氏度、5% $CO_2$、恒湿环境培养箱。

2. 细胞复苏步骤

1. 将配置好的完全培养基在 37 摄氏度水浴中提前预热。

2. 从液氮罐中迅速取出 Mel202 的冻存管，立刻整管投入 37 摄氏度恒温水浴箱中，轻微规律晃动。

3. 在 1 分钟之内令管内细胞急速融化（当内部仅剩最后一粒微小冰芯时捞出）。迅速用 75% 酒精擦拭冻存管外部消毒。

4. 在无菌生物安全柜内，用移液枪吸出细胞悬液，置于含有 5 mL 预热完全培养基的 15 mL 离心管中，轻柔缓慢地颠倒混匀以平衡渗透压。

5. 以 200 - 300 x g（约 1000 rpm）离心 3 - 4 分钟，小心吸除含有 DMSO 保护剂的上清液。

6. 加入 5 mL 新鲜完全培养基，用移液枪极其轻柔地吹打重悬细胞沉淀。

7. 接种于 T25 培养瓶中，置于 37 摄氏度、5% $CO_2$ 孵箱中培养。次日通过倒置显微镜观察细胞的贴壁展平形态及存活率。

3. 细胞传代与消化方法

• 传代时机：当细胞表面融合度达到 70% - 80% 时，必须及时传代。尽量避免细胞 100% 长满，否则紧密接触抑制会导致细胞老化或形态向不规则巨型多核转化。

• 传代比例：新接种密度建议控制在 $1 \times 10^4$ 至 $4 \times 10^4\text{ cells/cm}^2$，通常按照 1:3 至 1:4 的比例进行分瓶传代，每 3 - 4 天传代一次。

• 操作步骤：

  1. 吸除吸干旧的培养基。用无菌的无钙镁离子 PBS 轻轻洗涤细胞表面 1 - 2 次，清除残留血清。

  2. 加入适量的 0.25% Trypsin-EDTA 消化液（T25 瓶常规加入 1 mL），使其均匀覆盖整个贴壁细胞层。

  3. 放入 37 摄氏度孵箱中消化 2 至 4 分钟。在倒置显微镜下连续观察，当大部分上皮样细胞收缩变圆、细胞间隙明显增大、且轻击瓶壁细胞开始大面积成片滑落时，立即加入 2 倍体积的含血清完全培养基终止消化。

  4. 用移液枪平稳吹打瓶壁，使贴壁细胞完全解离分散为单细胞悬液。收集至离心管中，300 x g 离心 3 分钟，弃上清。

  5. 加入适量新鲜完全培养基，吹匀后按比例接种到新的培养瓶/孔板中。

4. 细胞冷冻保存

• 冻存液配方：90% 完全培养基（或纯 FBS） + 10% 优质细胞级 DMSO。

• 冻存操作：冷冻前确保细胞处于对数生长活跃期，且活力达 90% 以上。离心收集细胞沉淀，调整最终细胞密度至 $1.5 \times 10^6$ 至 $3 \times 10^6\text{ cells/vial}$。加入冻存液重悬分装至冻存管中，立即投入标准程序降温盒内（如 Mr. Frosty 梯度降温盒，维持 -1 摄氏度/分钟的降温速度），置于 -80 摄氏度冰箱过夜，次日必须迅速转移至 -196 摄氏度液氮罐中长期冷冻保存。

Part 2 English Section

I General Information and Genetic Architecture

• Cell Line Designation: Mel202 (commonly abbreviated as M202), Human Uveal Melanoma Cell Line.

• Species Origin: Homo sapiens (Human), Female.Originally isolated and characterized by Professor Martine Jager and colleagues at the Department of Ophthalmology, Leiden University Medical Center, Netherlands. It was recovered from a patient's primary uveal melanoma (UM) in situ tissue. As a foundational matrix of the European Commission's fifth framework infrastructure program "ESTDAB" (Database registration code: ESTDAB-128), its immunogenetic, mutation, and HLA parameters are fully mapped.

• Genomic and Mutational Profiles (Critical Background):

  • GNAQ Hyper-activation (Canonical Driver): Mel202 harbors the classical, hotspot oncogenic activation mutation in GNAQ (p.Gln209Leu / c.626A>T). This driver configuration is found in over 80% of primary ocular melanomas, causing structural hyper-activation of downstream MAPK cascades (RAS-RAF-MEK-ERK pathway) and YAP/TAZ signaling circuits.

  • SF3B1 Comutations: Possesses the splicing factor SF3B1 variant (p.Arg625Gly), a genetic hallmark tightly correlated with intermediate-to-high clinical metastatic dissemination profiles in uveal melanoma.

  • CDKN2A Loss: Features a frameshift regulatory knockout mutation in CDKN2A (p.Leu65Argfs*52), resulting in compromised cell cycle G1/S checkpoint governance.

  • BAP1 Phenotype: Retains normal, wildtype BAP1 protein output (BAP1-wildtype/positive), aligning with its origin from a primary tumor niche prior to entering extreme high-grade malignant clonal evolution.

• Immunological Baseline: Characterized by distinct human leukocyte antigen (HLA) restrictions, presenting as HLA-A*02:01 positive. It maintains stable structural expression of the melanoma-associated lineage antigen MART-1 (Melan-A), making it a rare, essential ocular model serving restricted immunotherapeutic engineering.

• Growth Topology & Morphology: Adherent matrix. Manifests predominantly as differentiated epithelial-like, polygonal, or interlaced spindle morphologies forming cohesive, dense single-layer clusters.

• Biosafety Matrix: Classified under Biosafety Level 1 or 2 (BSL-1/2). As a human-derived primary carcinoma lineage, all operational maintenance must proceed inside verified Class II Biosafety Cabinets under standardized sterile clinical lab routines.

II Strategic Research Value and Translational Fields

The Mel202 line serves as an indispensable in vitro platform to navigate ocular oncogenesis, signal transduction network mapping, and multi-drug targeted resistance:

1. Targeted Small-Molecule Screenings & MAPK Re-routing Cascades:

   Unlike cutaneous melanomas frequently driven by BRAF alterations (e.g., $BRAF^{V600E}$), uveal melanoma (UM) utilizes autonomous GNAQ/GNA11 upstream links, displaying universal intrinsic resistance against clinical BRAF inhibitors. Mel202 functions as the benchmark GNAQ-mutant preclinical target to discover, screen, and optimize novel MEK inhibitors (e.g., Trametinib, Selumetinib, TAK733), PKC inhibitors, or ARF6-directed blocking strategies, mapping single or combination synergistic lethality.

2. Adoptive Immunotherapy Competence & T-Cell Cytotoxicity Assays:

   Because Mel202 expresses intact MART-1 targets in tandem with the HLA-A*02:01 restriction axis, it is utilized worldwide as a validation platform to capture the lytic potency of MART-1-primed Cytotoxic T Lymphocytes (CTLs) or engineered TCR-T constructs. It assists in tracking effector cytokine discharge kinetics (IFN-$\gamma$, TNF-$\alpha$) and studying how chemotherapeutic regimens (e.g., Cisplatin / CDDP) sensitize immune non-responsive targets by up-regulating death-receptor FasR.

3. In Vivo Ocular Model Assemblies (Orthotopic Ocular Xenografts):

   Aids in the generation of standard subcutaneous tumor models or advanced orthotopic intraocular (anterior chamber or suprachoroidal space) xenografts within immunodeficient mice (e.g., BALB/c Nude, NOD-SCID). This models how ocular malignancies behave under the unique structural microenvironment of the eye and tracks mechanisms driving its dedicated organotrophic metastasis toward hepatic tissues.

III Thawing, Proliferation, Passaging, and Cryopreservation Routines

1. Formulating the Complete Growth Medium

Mel202 demands standard metabolic substrates but requires rigorous replenishment of L-glutamine reserves:

• Basal Medium: RPMI 1640 Growth Medium (Highly Recommended) (pre-fortified with 2.0 mM L-Glutamine).

• Complete Supplements:

  • 10% Premium Heat-Inactivated Fetal Bovine Serum (FBS).

  • 1% Sterilized Penicillin-Streptomycin cocktail (100 U/mL final working threshold).

• Environment: 37°C under a humidified atmosphere containing 5% $CO_2$.

2. Cryovial Thawing Routine

1. Pre-warm the formulated complete growth medium inside a 37°C water bath.

2. Extract the Mel202 cryovial from liquid nitrogen storage and instantly submerge it into the 37°C water bath with gentle, continuous horizontal agitation.

3. Achieve complete liquefaction rapidly within 1 minute (remove when a minimal frozen core remains). Swab the exterior thoroughly with 75% ethanol.

4. In a sterile biosafety hood, transfer the cell suspension into a 15 mL tube containing 5 mL of pre-warmed complete growth medium. Mix by smooth inversion to mitigate sudden osmotic shock.

5. Centrifuge at 200–300 × g (~1000 rpm) for 3–4 minutes, then cleanly aspirate the DMSO-laden supernatant.

6. Replenish with 5 mL of fresh complete medium, and smoothly resuspend the pellet via gentle pipetting.

7. Transfer the suspension into a T25 culture flask, and incubate at 37°C with 5% $CO_2$. Assess cell attachment profiles, alignment, and post-thaw viability under an inverted microscope the following day.

3. Subculturing and Cell Passaging Guide

• Confluency Cutoff: Subculturing must occur precisely when the monolayer hits 70%–80% confluency. Do not permit the sheet to hit absolute 100% saturation, as prolonged contact inhibition forces irreversible senescence or shifts cells toward giant multinucleated aberrant structures.

• Split Ratios & Seeding Density: Calibrate seeding densities to a baseline of $1 \times 10^4$ to $4 \times 10^4\text{ cells/cm}^2$. Split the flasks utilizing standard ratios ranging from 1:3 to 1:4 every 3 to 4 days.

• Step-by-Step Harvesting Routine:

  1. Aspirate spent medium and rinse the cell sheet 1–2 times with sterile, calcium/magnesium-free PBS to remove residual serum proteins that neutralize trypsin.

  2. Add an appropriate volume of 0.25% Trypsin-EDTA Solution (approx. 1 mL for standard T25 flasks) to completely submerge the layer.

  3. Incubate at 37°C for 2 to 4 minutes. Monitor continuously under an inverted microscope; as soon as the epithelial-like boundaries round up, contract, and begin detaching upon gentle mechanical tapping against the side of the flask, instantly add a double volume of serum-containing complete growth medium to quench enzymatic degradation.

  4. Gently pipette the vessel surfaces to yield a homogeneous single-cell suspension. Centrifuge at 300 × g for 3 minutes, then discard the supernatant fluid.

  5. Disperse the pellet into fresh complete medium, split according to target ratios, and allocate into new culture vessels.

4. Cryopreservation Protocol

• Freezing Medium Matrix: 90% Complete Growth Medium (or pure premium FBS) supplemented with 10% analytical-grade cell-culture DMSO.

• Freezing Routine: Harvest active, log-phase cells showing >90% cell viability metrics. Centrifuge and resuspend the cell mass to hit a final concentration baseline of $1.5 \times 10^6$ to $3 \times 10^6\text{ cells/vial}$. Aliquot into sterile cryovials and transfer immediately into a standardized controlled-rate freezing box (e.g., Mr. Frosty container, ensuring a constant thermal drop profile of -1°C/minute). House at -80°C overnight, and shift the vials into the liquid nitrogen vapor phase (-196°C) the following day for long-term preservation.

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